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Publication numberUS3888678 A
Publication typeGrant
Publication dateJun 10, 1975
Filing dateOct 9, 1973
Priority dateJul 16, 1971
Publication numberUS 3888678 A, US 3888678A, US-A-3888678, US3888678 A, US3888678A
InventorsJr William J Bailey, James F Houle, Norman Gilden R Van
Original AssigneeEastman Kodak Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method for adjusting triboelectric charging characteristics of materials
US 3888678 A
Abstract  available in
Images(38)
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Claims  available in
Description  (OCR text may contain errors)

United States Patent [191 Bailey, Jr. et al.

[ June 10, 1975 Houle; Gilden R. Van Norman, all of Rochester, NY.-

[73] Assignee: Eastman Kodak Company, I Rochester, NY.

22 Filed: Oct. 9, 1973 21 Appl. No.:' 404,552

Related US. Application Data [62] Division of Ser. No. 163,450, July 16, 1971,

abandoned.

[56] References Cited UNITED STATES PATENTS 5/1966 Chu et a1. 96/85 12/1970 Pechmann 96/87 Mackey et a1. 96/87 3,552,972 l/l97l Meyer et al 96/87 3,573,093 3/1971 Osnibuchi et al.... 96/87 3,589,906 6/1971 McDowell et a1. 96/] 14.5

3,607,286 9/1971 Wood 96/87 3,666,478 5/1972 Groix et al 96/94 Primary Examiner- Norman G. Torchin Assistant Examiner Edward C. Kimlin Attorney, Agent, or Firm-E. W. Milan 57 ABSTRACT Method for adjusting the charging characteristics of surfaces are disclosed. A preferred embodiment relates to methods for altering the contact surfaces of materials that are ordinarily subject to the production of relatively large scale triboelectric effects when such a surface is frictionally contacted with another surface, to thereby eliminate or minimize the potential for undesired static electric discharge, for example. The present methods involve altering such a surface with a charge control agent as defined herein to thereby provide a desired, predetermined adjustment in the triboelectric charging propensity of the surface. Specific products having minimized, maximized, narrowly adjusted (as desired) surface impact charging characteristics are disclosed.

78 Claims, No Drawings METHOD FOR ADJUSTING TRIBOELECTRIC CHARGING CHARACTERISTICS OF MATERIALS This is a division of application Ser. No. 163,450, filed July 16, 1971, now abandoned.

The present invention relates to the general subject of static electricity formation and accumulation or discharge when one surface is frictionally contacted with another. More particularly, this invention relates to novel processes and compositions useful in influencing, in a desired manner, the impact charging characteristics of such surfaces.

THE PROBLEM In the manufacture and use of polymeric film products and especially sensitized (radiographic or photographic) materials, the generation of static electrical charge is a serious problem. In the case of sensitized goods the most serious deleterious effects are produced when accumulated electrical charges discharge, producing light and/or noise, which is recorded as an image on photosensitive materials and as static on other materials such as magnetic tape that are sensitized to other specific, non-visible electromagnetic irradiations. Such discharge may occur in the course of manufacturing processes, such as coating, finishing or packaging, or it may occur during use of the finished product in cameras, printers, tape players and other associated equipment.

Another less obvious deleterious effect which results from accumulation of charge on polymeric supports, coated or uncoated, in the manufacturing operation, is the production of coating defects such as core mottle and roll convolution repeat, both of which are well known to those involved in the manufacture of these types of materials. Both of these undesirable effects'are due to the uncontrolled, undesirable build-up of localized electrically charged areas on, or in the various products in the course of the film manufacturing operation.

These areas of localized charge give rise to nonuniformity in the overlying sensitized coatings during their application and consequently the aforementioned manifestations of this non-uniformity.

Although there are a large number of manipulative ways in which such undesirable (and often hazardous) static electrical charges can be generated, the term most applicable to the generation of electrical charge in the manufacture and use of sensitized goods is triboelectricity. This term refers generally to the electrical charge generated by the contact or dissociation (physical separation) of two surfaces. Usually, but not always, the two surfaces are dissimilar. The amount of charge generated in this fashion is dependent upon several factors, the most important being: 1 the intimacy of contact; (2) the time of contact; and (3) the nature of the surfaces brought into contact. It is significant, however, that multiple contacting and dissociation of different surfaces during the various manufacturing operations can, and very often do, result in the build-up of very large charges of so-called static electricity" in and on the various products and parts of equipment involved in such operations; the net effect upon the charge induced upon the contacted surface(s) being known as the triboelectric effect" of such contact and dissociation. Apparently each contact between surfaces results in a specific charge effect upon the surfaces involved, generally with a total cumulative charge being built up on the surface(s) in an additive manner; the particular electrically conductive nature of the material in question is generally determinative of the actual-observed rate of build-up. Unfortunately, very few polymeric films or coated photographic film materials are sufficiently electrically conductive by themselves to prevent static electricity build-up to an objectionable degree during the ordinary processing of such materials.

There have been many approaches to eliminating or minimizing so-called static-defects" which are the manifestation of the presence of excessive triboelectricity. Inasmuch as a static mark in photographic products is the result of light recorded by the sensitized layer, there is a certain minimum electrical charge required before a discharge which produces light of sufficient intensity or duration to be recorded by a particular sensitized layer can occur. In the case of a polymeric film such as cellulose acetate coated with a conventional, mainly gelatin-based photographic emulsion, for example, static discharge occurs when a net triboelectric charge of +8-l0esu (electrostatic units per square centimemter) at a given part of the emulsion is reachced. This FIGURE will of course vary quite broadly with materials, humidity conditions, etc. In this instance, the mainly gelatin surface of the emulsion exhibits a marked positive triboelectric tendency. measured against many surfaces with which such a mainly gelatin layer is contacted during its manufacture. Other surfaces accumulate negative triboelectric charges preferentially. However, undesired static discharge can occur due to either excessively negative or excessively positive surfaces. Any discussion of proposed solutions to the static defects problems should be with an understanding of the foregoing factors which govern the type and relative amount of charge generated between generally dissimilar surfaces.

PRIOR ART There have been, and continue to be, an almost endless list of attempts to prescribe methods for decreasing or eliminating the effect of charge accumulation. The intimacy of contact of the surfaces of photographic materials has been altered by incorporating matting agents into one or more of these surfaces. These modifications have been only partially effective since the duration and/or multiplicity of contacts often destroys any benefit achieved by reducing intimacy of contact. Time of contact can be varied, but not within sufficiently practical limits to alleviate the problem and furthermore, this type of approach generally involves modification of external influences which occur in the environment of the film.

Perhaps the best known and most widely used type of effort to solve this problem involves the incorporation of so-called conductive materials or layers as a film backing or in mixture with a binder to hopefully conduct the electrical charge to ground as it occurs to avoid any discharge sufficient to produce recordable static energy. Some of the conductivity improving materials, although highly conductive, are themselves quite prone to generating large quantities of electrical charge when contacted with a dissimilar material. Thus, so much charge is often generated in each single impact that the charge cannot be conducted to ground rapidly enough to prevent static discharge from occurring. Furthermore, the great bulk of such conductivity improving materials depend upon an environment having a relatively high relative humidity to perform well as conductors of static electricity. For example,

whereas they may perform satisfactorily as conductors under conditions of relative humidities of 50 percent or more, many of them cannot conduct adequately when they are made or used in atmospheres having relative low humidities, on the order of or even less. This type of experience results from the use of ionic and/or hygroscopic materials which depend for their conductive properties upon their ability to dissociate under high humidity conditions. Often surface tackiness is another problem associated with the use of such conductivity improving materials that function in this manner. An outstanding example of the tackiness phenomenon occurs in the case where an ionic or hygroscopic conductivity agent is incorporated into the gel sub layer of, for example, a poly(ethylene terephthalate) or other polymeric based photographic element in an attempt to prevent static discharge which ordinarily occurs during the emulsion coating operation due to contact of the sub with rollers, etc. In order for this type of conductivity agent to perform statisfactorily, humidity levels within the coating machine must be maintained at about 50 percent. At this level, however, the gel sub becomes tacky and results in what is popularly called gel-pickof in the film coating art. In this case the tackiness of gel layer causes small pieces of gel to adhere to the transporting and other rollers giving rise to a sub layer replete with holes and in turn a very poor emulsion overcoat. The picked of gel may become redeposited from the rollers back onto other areas of the film producing gel spots," another undesirable defect. Clearly, in many instances, it is desirable to minimize or eliminate static discharge by some method other than the use of such hygroscopic conductivity improving materials.

Since the contacting and dissociation of dissimilar surfaces during the manufacture of various photographic and radiographic elements is quite necessary, it appears from the prior art and prior to the present invention that the problem of excessive charge generation due to triboelectric effects (along wiwth the concomitant relatively large amount of waste or unsatisfactory product) had to be accepted as a part of the cost of being in this business, since this phenomenon is a natural physical occurrence. All prior attempts at solving the problem of static discharge have apparently been directed to trying to drain off the charge quickly and efficiently, rather than attempting to overcome this apparent natural physical occurrence in the first instance.

OBJECTS It is therefore an object of the present invention to provide a method for controlling, within prescribed useful limits, the charging characteristics of materials utilized in the manufacture of radiation and/or. photosensitive materials.

It is another object of the present invention to provide photosensitive products whose outermost surfaces are either (a) substantially charge free when impacted with dissimilar materials or (b) alternatively, produce sufficiently low levels of charge when so impacted that charge accumulation in their normal environment is not sufficiently high as to produce discharge; or if charge accumulation does occur under severe environmental conditions, means are provided to conduct this charge off of the surface in a controlled fashion without discharge or any of the aforementioned problems.

It is yet another object of the present invention to provide .a method for establishing the triboelectric charging characteristics of surfaces intended for almost any use at any predetermined level based upon the nature of the treated surface and that with which it is brought into contact. Thus, these characteristics may be minimized or carefully controlled within relatively narrow limits.

Other objects and advantages of the present invention will be made obvious to those skilled in the art by consideration of the following description.

SUMMARY OF THE INVENTION According to the present invention, there is provided a method for doctoring the surfaces of materials normally subject to the generation of a triboelectric charge when a surface thereof is brought into contact with another usually dissimilar surface by modifying the surface of the material with a sufficient amount of a selected charge control agent to thereby provide to that surface a preselected, desired triboelectric charging characteristic.

According to a preferred embodiment, selection of the charge control agent and adjustment of charging characteristics comprise the steps of:

a. measuring the electrical charge generated when the surface of the material normally subject to triboelectric charging is brought into contact with another selected, usually dissimilar surface under controlled conditions;

b. measuring the electrical generated when surfaces containing charge control agents are brought into contact with a similar usually dissimilar material under controlled conditions;

c. based on the results of step (b) selecting a charge control agent which provides the adjustment desired for controlling the charging characteristics of the material; and

d. modifying the surface of the material with a sufficient amount of the charge control agent selected in step (c) to produce the desired adjustment in the charging characteristics of the surface of the material.

.There are also provided herein a number of specific radiation sensitive materials and film base materials in which surface charging characteristics have been substantially nullified utilizing the foregoing technique; said materials comprising elements having charge control agents, (as defined in detail hereinafter) incorporated into one or more layers thereof.

More specifically, charge control agents of the following generic classes have been found to be suitable additives in certain limited classes of materials;

A. surfactant materials having the generic structure:

A is a member selected from the group consisting of hydrocarbon chains partially fluorine substituted hydrocarbon chains and fluorocarbon chains;

Z is a member selected from the group consisting of H II -S-NH, -C-NH, -S-NH- and n is an integer ranging from l to about 8; D is wherein R R and R are f selected from the group consisting of hydrogen, lower alkyl and aryl;.and X is an anion. According to the preferred embodiments of the present invention X is selected from the group consisting of chloride, bromide,

iodide, nitrate and phosphate ions; g

8. compounds of the following structural formula: I

wherein:

Z represents the atoms necessary to constitute a member selected from the group consisting of aromatic hydrocarbon rings and alicyclic structures;

R is selected from the group consisting of single and multiple substitutions of members selected from the group consisting of halogen, nitro, nitroso, hydroxyl, carboxy, cyano, alkoxy, aryloxy, substituted alkoxy and n -C-0R wherein R is alkyl, aryl, substituted alkyl, or substituted aryl;

X is a member selected from the group consisting where ifR l) or (2) and'R, is hydrogen, R is selected from the group consisting of halogen. nitro,aryl.

substituted aryl, hydroxyl, where if R (3) R and R may be hydrogen. halogen, nitro, carboxyl, aryl, substituted aryl, alkyl, and substituted alkyl n and m are integers which may be the same or different, and where R is H, R may be hy D. carboxylated polymers in the free carboxyl form as described hereinafter;

E. compounds of the formula and CH=CH-- wherein n is an integer from 1 to 40 F. polymeric structures havingareptitive substitutent about 10; J

Y is a member selected from the group consisting of l. 0 when M is a member selected from the group consisting of hydrogen, ammonium, metallic cations,

and amine salt residues 2. NH when M is H 3. C=O when'M is selected from'the group consisting of phenyl and substituted phenyl.

C. Multifunctional carboxylic acids of the general formula:

HOOCR-COOH wherein R is selected from the group consisting of:

Gilla 3 CH R 2r\ 1 Z capable of contributing a negative charging influence, as defined in greater detail hereinafter.

DETAILED DESCRIPTION OF THE INVENTION At this stage of the discussion, it would perhaps be helpful to define internal environment and external environment as it relates to the static generation problem, as this terminology will be used frequently hereinafter. By internal environment" is meant the manufacturing or in process environment which a particular' problems experienced in this external environment will be referred to as external charging problems.

As one might expect, internal charging problems .can often be corrected or eliminated by modification of manufacturing equipment to match the surfaces thereof to the surface of the processed material so that charging effects are reduced to a minimum. Such alterations are, however, often quite difficult and expensive, and, as a practical matter, all but impossible without extensive and costly re-engineering etc. In the case of external problems, however, such modification is all but impossible since the film manufacturer has no control over types of parts in, or the design of, the particular equipment in which the manufactured material is to be used, or any other aspect of the products external surroundings.

The term charge control agent as utilized herein and in the claims appended hereto refers to a material of known triboelectric charging propensity as determined in the apparatus and according to the method described in US. Pat. No. 3,501,653 to W. .l. Bailey, Jr. issued Mar. 17, 1970, or some equally accurate technique, which material is also capable of incorporation into or coating on a surface to adjust the triboelectric charging characteristics thereof. Specifically preferred materials within this broad class are described in detail below and are capable, when properly selected, of minimizing the generation of static electrical charges in many products including, for example, radiation sensitive film and polymeric materials of the type used in film, sheeting fabric and carpet manufacture. As described hereinafter, maximization or intermediate adjustment of surface charging characteristics may also be achieved using the techniques described herein.

The foregoing charge control agents are further distinguished from conductivity agents i.e., materials which due to the fact that they are hygroscopic and/or ionic tend to conduct or bleed off static charges gener ated by contact between two surfaces thereby minimizing the accumulation of same. Thus, in the preferred embodiments disclosed herein, charge agents can be used to minimize, maximize or adjust to prescribed level the propensity of a given surface to generate static electrical charges when contacted with another usually dissimilar surface, while the conductivity agents of the prior art merely minimized the accumulation of static electrical charges ex post facto i.e., after generation thereof.

The instant pursuit of a solution to the abovedescribed problem was initiated by subjecting the phenomenon itself to systematic scrutiny, as opposed to pursuing attempts to compensate for the phenomenon once its effects manifested themselves as had been done with conductivity agents, for example, in the past. Thus, a method for accurately measuring the magnitude of the effects had to be devised to determine the mechanism, effects and charging propensities of various materials. Several methods were available to evaluate or measure the amount of accumulated charge built up when dissimilar materials were brought into contact or removed from contact. Such prior art methods involved measurement of contact potential between dis similar materials; blocking potential; charge accumulation due to rolling or sliding friction; etc.

Most of these methods involved so many variable factors in the system under study that in many cases anomalous results or results which were not a true measure of the net charging propensities of the surfaces involved were obtained. A method of measurement which eliminates many of the variable factors in some of the earlier equipment and yields results more clearly dependent upon actual surfaces, time of contact and pressure, is identified as the impact electrification" method. An instrument to measure impact electrification" is described in US. Pat. No. 3,501,653 to W. J. Bailey, Jr. issued Mar. 17, 1970. The instrument and the measured values obtained in the use thereof are defined and explained thoroughly therein and the disclosure of this patent is incorporated herein by reference. Stated simply, the theory of Baileys apparatus is that if accurate comparative values for impact electrification of a variety of surfaces is to be determined, a given reference surface must be impacted by a second (reference) surface and separated, all in a controlled and repeatable manner. The electrical charge generated by the impact and separation is accurately measured and recorded. The values obtained are most conveniently expressed in electrostatic units per square centimeter (esu/cm The amount of electrical charge in esu/cm responsible for discharges causing static marking for some photographic elements is discussed hereinafter.

With such aninstrument one is able to study the effects on the electrical charging behavior of various surcontrol faces. Furthermore,.one is able to relate these data to behavior of such a surface when used in conjunction with a photographic element provided that certain variables are brought into consideration.

With this impact electrification meeasuring apparatus and technique, a detailed study was initiated to determine the relationship between chemical structure and electrical charging behavior; namely impact electrification. It was postulated that if such a relationship could be determined, one could possibly use the same to design compounds or materials which control the electrical charging behavior of photographic elements such that a static discharging amount of potential would not be obtained in the first instance. It was then discovered thatthis desirable goal can be accomplished by practicing the present invention. Furthermore, it was found that the control of surface charge to aid coating uniformity of the sensitized portions of the element (rather than detract from it) is also possible, and can be accomplished by practicing the instant invention. Thus, according to the present invention there is provided a method for adjusting the charging characteristics of materials normally subject to the generation of an electrical charge when a surface thereof is brought into contact with and dissociated from another (usually dissimilar) surface by modifying the surface of the material with a sufficient amount of a selected charge control agent to provide a desired preselected charging propensity. According to a preferred embodiment of the invention testing, selecting and adjusting technique comprises the steps of:

a. measuring the electrical charge generated when the surface of material normally subject to triboelectric charging is brought into contact with another usually dissimilar surface under controlled conditions;

b. measuring the electrical charge generated when surfaces of charge control agents" are brought into contact with a similar usually dissimilar material under controlled conditions;

c. based on the results of step (b) selecting a charge control agent which provides the adjustment desired for controlling the charging characteristics of the material surface; and

d. modifying the surface ofthe material with a sufficient amount of the charge control agent selected in step (c) to produce the material.

According to the method of the present invention, a surface which is subject to charging upon physical contact with another dissimilar surface is tested, preferably in the apparatus described in the aforementioned U.S. Pat. No. 3,501,653, to determine the electrical charge generated when the surface is brought into contact with a specific dissimilar material under carefully controlled and reproducible conditions of time, impactforce, intimacy of contact, relative humidity, etc. to determine the charge generated under such conditions of controlled impact and dissociation. Once a value has been determined for this charge, a variety of other surfaces ofcharge control agents? i.e., materials which may be incorporatedonto or into the surface originally evaluated, as define hereinabove, are similarly tested by impacting under the same controlled conditions with the same generally dissimilar surface. From the results obtained in the two evaluations just described a charge control agent" which demonstrates charging characteristics, which, when added to those of the surface to be altered, provide the desired surface charging adjustment is selected and an amount sufficient to provide the desired alteration coated on or "incorporated into the surface. According to a preferred embodiment wherein it is sought to minimize the propensity of the surfaces of radiation sensitive film base or radiation sensitive elements to generate static electrical charges when contacted with specific reference surfaces charge control agents demonstrating triboelectric charging propensities of about the same magnitude, but of opposite polarity as the surface whose charging is sought to be controlled are selected and amounts thereof sufficient to neutralize" or nullify the charging of the surface incorporated therein, in, for example, the surface formation operation i.e., casting extrusion, etc. or by coating of a very thin, continuous or discontinuous, layer of the charge control agent over the surface whose charging characteristics are being altered. A brief single deomonstrative example of which many more will be presented hereinafter exists in the case of sensitized photographic materials as already mentioned above.

In the manufacture of silver halide sensitized photographic materials the light sensitive silver halide is suspended in a gelatin emulsion which is in turn coated, generally at a very high speed, on a cellulose ester, poly(ethylene terephthalate) or other suitable support. In the case of poly(ethylene terephthalate) materials, due to the hydrophobic properties thereof, it is necessary to pre-coat" the support with an emulsion adherence improving gelatin sub of the type well known to those skilled in the film manufacturing art. This sub is applied directly to the polymeric support or a u-coat applied thereunder and dried. The coated support is then emulsion coated at high speed in a roller transport coating machine or other suitable transport mechanism which might similarly produce triboelectric charging. With each impact of the gel subbed surface with a stainless steel or anodized aluminum roller during the emulsion coating operation a charge is produced which ultimately may result in a discharge if the accumulated static achieves or exceeds a prescribed discharge threshold level. To control this phenomenon in accordance with the technique described herein, a surface of the gel sub was tested to determine its impact electrifi cation potential in the apparatus and according to the method described in the aforementioned U.S. Pat. No.

3,501,653. The results of this test indicated that at an impact pressure of 20 Psi, relative humidity of 5 percent, F and other controlled conditions specified below, the gel surface produced a charge of about +20 esu/cm when the impacting material i.e., the roll material was stainless steel. Testing under similar environmental conditions utilizing surfaces of a variety of charge control agents, i.e., materials capable of incorporation into the gel surfaces, which demonstrate their own individual charging characteristics, indicated that a class of materials identified as group A or B. described in detail below, had very strongly negative charging characteristics on the order of 30 esu/cm With this information in hand, small amounts of these negative charging agents were incorporated into the gel sub and with some small amount of varying of ratios it was discovered that if concentrations of from about 1 g/g of gel to about 2 g/g of gel of these materials were used, a surface which demonstrated a charge of about 0i0.5 when tested according to the technique of U.S. Pat. No. 3,501,653 could be produced.

Further efforts in this area indicated that it was possible by incorporating relatively small amounts, on the order of 0.005 percent by weight of the fluorocarbon materials of group A above, into the gel sub to produce subbed support materials which generated almost no charge when impacted in the controlled fashion described. These materials when subsequently emulsion coated in a conventional apparatus utilizing stainless steel rolls demonstrated uncommonly low levels of static charging over a broad range of humidity conditions, thus providing exceptional processing advantages, and emulsion coated product which was free of static marking.

Although in the preferred embodiment, the charge magnitude of the charge control agent approximates that of the surface whose charge is being modified, (except, of course, that it is of the opposite polarity) it should be obvious that in fact such close matching of charge magnitude is not absolutely necessary since a relatively smaller amount of a charge control agent which demonstrates a charging propensity of greater magnitude can be incorporated into or coated on a charging surface to achieve a combined charging potential of about zero. Such a combination of high magnitude charging charge control agent and a charging surface of opposite polarity and relatively lower charging potential provides the added advantage that only very small quantities of the control agent need be introduced into the very sensitive and delicately balanced photographic systems in which the product is primarily useful, thereby reducing the possibility of sensitiometric problems which may and often do arise when additives are incorporated into such materials.

It should also be noted that although a wide variety of charge control agents including ionizable salts, acids, alcohols, esters, ethers, etc. as described in detail hereinafter, may be incorporated to provide the desired charge control, it is particularly advantageous if the charge control agent is a surfactant since this permits the formation of a hybrid surface of charge control agent and charging surface with relatively minimal concentrations of the former, thereby further reducing the amounts of charge control agent which must be added to achieve the desired level of charge control and concurrently the level of potential problems which may result from such incorporation by the use of surfactants",

however, care should be taken not to combine interacting or reacting surfactants or charge control agents as will be described in greater detail below. Use of such interacting materials can often result in undesirable repellency characteristics and/or even sensitiometric defects and reasonable care must be exercised to avoid any such use.

The foregoing discussion has been directed primarily to the control of charging so as to provide a surface which, when subjected to impact charging, produces a charge of about esu, as is desirable in the manufacture of photosensitive products. The techniques described can be similarly employed to enhance or increase the magnitude of the charge produced on a surface upon impact. For example, in the application of toners to exposed areas in electrophotography, it is necessary to produce a very high charge on the surface of the toner particles to insure their repulsion by the non-image, similarly charged areas and attraction to the oppositely charged image areas. Hence, in this application, the desire is indeed to increase the surface charging of the toner particles or the imaging materials to some predetermined relatively high level and this can be accomplished by the incorporation of a suitable high charging charge control agent into or onto the surface of the toner particles to substantially increase the surface charge of the toner to any desired level and any desired polarity. The selection of surfactant materials or alternatively materials which can be coated in very thin layers or imbided into the surface for this purpose produces advantages similar to those stated for photographic usages in that lesser concentrations of such materials are required to produce surfaces having relatively large concentrations thereof.

Thus, as should be clear the method of charge adjustment or surface alteration described herein is equally applicable to increasing the impact charging characteristics of surfaces as to reducing the same to the zero level, as is highly desirable in the case of the manufacture of radiation sensitive materials.

As a further alternative, due to the differences which occur between internal and external static inducing environments it may be necessary to include on the surface of a given product in addition to one or more of the charge control agents described above, a more conventional conductivity agent which would serve to conduct or bleed off triboelectricity produced over and above certain maximum threshold levels as defined for specific products.

This phenomenon can once again be defined in terms of the photosensitive material described above wherein the technique of the instant invention is utilized to select a charge control agent or combination of charge control agents which are incorporated into the gel sub surface to eliminate static effects in the internal environment, due to impact with a specific impacting material, namely stainless steel rollers. This same product may, however, after sale, be subjected to an external environment including impacts with plastic, rubber, aluminum, etc. materials for which the original charge control agent provides little if any protection, and may indeed actually tend to produce increased charging.

Under these circumstances, the incorporation of a conductivity agent as well as a charge control agent becomes a requirement to insure that the article is free of the effects of charge accumulation. Such combinations will be discussed further and examples thereof presented hereinbelow.

As alluded-to hereinabove, the use of mixtures or combinations of two or more charge control agents to achieve very exact definitions of the surface charging characteristics of a given material may also be advantageous, and combinations of this type will be demonstrated in the examples below.

Some specific examples of photosensitive products developed as a result of utilization of the abovedescribed technique and utilizing materials evaluated in the foregoing examples will now be defined in detail.

Among the types of materials which have been found useful as charge control agents to date are the following classes of compounds:

A. surfactant materials having the generic structure:

wherein: I

A is a member selected from the group consisting of hydrocarbon chains, and partially and per-fluorinated hydrocarbon chains;

wherein R R and R are selected from the group consisting of hydrogen, lower alkyl and aryl; and

X is an anion. (In the preferred embodiment, X is selected from the group consisting of chloride, bromide, iodide, nitrate and phosphate ions.)

B. compounds of the following structural formula:

wherein:

Z represents the atoms necessary to constitute a member selected from the group consisting of aromatic hydrocarbon rings and alicyclic structures;

R is selected from the group consisting of single and multiple substitutions of members selected from the group consisting of halogen, nitro, nitroso, hydroxyl, carboxy, cyano, alkoxy, aryloxy substituted alkoxy, and

wherein R, is alkyl, aryl, substituted alkyl or substituted aryl;

X is a member selected from the group consisting and CH=CH wherein ri=an integer from] to about 10, t

Y is amember selected from the group consisting of (l) when M is a member selected from the group consisting of hydrogen, ammonium, metallic cations,

and amine salt residues; (2) NH when M is H; and (3) wherein R is selected from the group consisting of:

where if R=(1) or (2) and R, is hydrogen, R2 is selected from the group consisting of halogen, nitro, aryl,

substituted aryl, hydroxyl,

where if R=(3) R1 and R may be hydrogen, halogen, nitro, carboxyl, aryl, substituted aryl, alkyl and substituted alkyl n and m are integers which may be the same or different and where R, is H, R may be hydroxyl D. carboxylated polymers in the free carboxyl form as described hereinafter;

E. compounds of the formula F. polymeric structures having a repetitive substituent capable of contributing a negative charging influence, as defined in greater detail hereinafter.

According to the preferred embodiments of the present invention the following members of the various groups of charge control agents A-F have been found most effective in the manufacture of photosensitive materials in view of their relatively less positive charging propensity. Of course, any of the members of these groups as well may also be used to enhance surface charging characteristics as described above. The members include A. those compounds wheein A is a partially and even more preferably a completely fluorinated chain;

B. the sodium and potassium salts of the substituted benzene sulfonic acids;

C. multifunctional carboxylic acids such as citric, tartaric, succinic;

D. compounds having the following general structures: I.

, pro- 2)- C OOH C OOH wherein Z may be (a) CH CH -Cl-l CH- wherein R is lower alkyl, and

-cu CH- wherein R is lower alkyl, halogen, hydroxyl, nitro etc;

R I II. 2

COOH

where R is H or methyl;

0- 0 '1 II -o Z l noom wherein Z represents the atoms necessary to complete: (a) a polyester (i.e., a diol residue); (b) a polyamide; (c) polycarbonate, etc. and n is an integer from 1 to 4;

(-cn en awherein n is an integer from 1 to 4; and

V. polymers containing both hydroxyl and aromatic carboxylic acid groups;

E. lower alkyl phosphates; and

F. repetitively halogen, nitro and hydroxyl substituted polymers.

Carboxylated polymers of the type described in D above have been used in their salt forms conductivity agents, however, we have found that the use of carboxyl containing polymers in the free carboxyl form provide the desired negative charging influence in gelatin photographic materials. Such materials cannot, however, be used as conductivity agents in this form since the surface electrical conductivity thereof is far too low for practical purposes. Furthermore, the salt forms of the carboxyl containing polymers do not show the highly desirable negative charging influence of the free carboxyl groups.

Among the materials included in Class E described above are several which are useful as coating aids or conventional surfactants, however, when used as charge control agents in the context of this application the concentration levels are generally below on the order of 0.1 gram of ester per gram gelatin or 4 micrograms per square centimeter.

Insofar as the members of group F above are concerned it should be noted that copolymers containing substituent groups capable of influencing the charging properties of polymeric materials in a negative direction to any desired level by varying the ratio of negative charging substituents present a myriad of possibilities all of which cannot be recorded here.

The following is a partial list of the specific compounds from among the aforementioned classes which have demonstrated the effects desired: p- Nitrosophenol Sodium Salt; p-Aminobenzoic Acid; p- Nitrobenzoic Acid; 2,4,6-Trinitrobenzoic Acid; Sodium Benzoate; p-Nitrophenol; Pieric Acid; Trinitroresorcinol; p-Nitrobenzene Sulfonic Acid; 3- Nitrophthalic Acid; P-Nitrocinnamic Acid; diH Benzene Phosphonate p-Nitrobenzene Sulfonic Acid, Sodium Salt, p-Nitrophenylacetonitrile; p- Nitrophenylacetic Acid; p-Nitrophenoxy Acetic Acid, 3-Nitrochalcone; 2,6-dinitrothymol; 2,4-dinitro-lnaphthol-7-Sulfonic Acid; 4-Nitrophthalic Acid; p- Nitrobenzamide, 2,4,6-Trinitrobenzene Sulfonic Acid; m-Nitrobenzene Sulfonic Acid, Sodium Salt; p- Nitrobenzene Sulfonic Acid, dibutylamine salt; 4- Chloro-m-Toluene Sulfonic Acid; p-Fluorobenzene Sulfonic Acid; p-toluene Sulfonic Acid (hereinafterp- T.S.A.), p-Chlorobenzene Sulfonic Acid, Sodium Salt; p-Bromobenzene Sulfonic Acid, Sodium Salt; 2,5- dichlorobenzene Sulfonic Acid; p-Hydroxybenzene Sulfonic Acid, Sodium Salt; 0(carboxy methoxy) Benzoic Acid; p-hydroxy Benzoic Acid; p- Chlorophenylacetic Acid, 4,4-Biphenyl disulfonic Acid, 2,5-Dichlorosulfanilie Acid, Sodium Salt; Sulfosalicyclic Acid, 4-sulfophthalic Acid, mono Sodium Salt; 2,2'-Diphenic Acid; Trimellitic Acid; Benzene Sulfonic Acid (hereinafter B.S.A.), B.S.A., didodecylamine Salt; B.S.A., dibutylamine Salt, p-T.S.A.,

(COOl-l) IV.

tridodccylamine Salt; p-T.S.A., didodecylamine Salt; p-T.S.A. tridodecylamine Salt; p-T,S.A., didodecylamine Salt; pT.S.A., trimethylamine Salt; 4- Sulfophthalic Acid, dibutylamine Salt; B.S.A. tridodecylaminc Salt; B.S.A. tributylamine Salt; p- T.S.A.. triethylamine Salt; p-T.S.A., tributylamine Salt; Pyromellitic Acid; Terephthalic Acid; Phthalic Acid; MelliticAcid; Citric Acid; Salicyclic Acid; d'Tartaric Acid; Succinic Acid; Oxalic Acid; Malonic Acid; Malic Acid; Maleic Acid; Adipic Acid; Fumaric Acid; Hydroquinone; Glutaric Acid; L-Tartaric Acid, 50-50 D-. L- Tartaric Acid; Pyromellitic Acid, Mono Sodium Salt; 1,3-dicarboxymethyl-5 benzenesulfonic Acid, Sodium Salt; pyromellitic Acid NHJ pH 4.3; pyromellitic Acid NH, 8.2; 5-Sulfoisophthalic Acid Sodium Salt; 5- Sulfosalicyclic Acid, Trimellitic Acid, Trimesic Acid, compounds of the following empirical formulas C H CONH(CH N 1 ,Me C l-l CONH-(CH -N-Me I \Me l ,Me 1 Ni-Me I" cellulose acetate phthalate, hexahydrophthalate,

trimelitate etc., poly(vinyl chloride), poly(vinylidene chloride), poly(chlorostyrenes), poly(nitro styrenes), poly(vinyl phenols), poly(vinyl chlorobenzoate), poly(vinyl nitro benzoate), and poly(vinyl nitro phthalate).

Among the photographic products which have'demonstrated the most problem with triboeleetric effects are X-ray and Aero film materials. Due to the peculiar nature of the internal and external environment of each of these classes of photosensitive products they provide especially difficult problems whose solutions are critical to the production of the high resolution, extremely high quality presently demanded in the markets for these products. Utilizing the techniques of the instant method, promising products have been developed in each of these areas and these are described individually hereinafter as a non-limiting means of defining operative techniques, compositions and structures embodying the successful practice of the instant invention.

X-Ray Materials In the manufacture of x-ray materials at the high coating speeds described earlier, considerable discharge generally occurs. It is in products of this nature that gel pickoff due to relatively high humidity conditions in the coating machine becomes prevalent. In an attempt to solve these problems, measurements were made using well known techniques to determine the maximum amount of triboelectric charging which could be tolerated on a single impact between a gel subbed x-ray polymeric base and stainless steel and anodized aluminum rollers used to transport the subbed base through the coating machine. This analysis indicated that a maximum single impact charge of about -1 2 esu/cm was the most-which was tolerable, since above this level at the low humidities required to prevent gel pickoff, even with conductivity agents, the cumulative charge built up could not be drained off fast enough and eventually resulted in destructive and often equally spectacular static discharges in the coating machine on the order of two feet in length. This maximum or threshold level of single impact charge will of course vary depending upon the number of rollers in a given machine, machine speed, relative humidity, etc.; however, it will be taken as a target level for purposes of the instant discussion.

Thus, the immediate problem becomes one of maintaining the single impact charging level below about 10 esu/cm":

Using the techniques and data presented above, it was determined that compounds of class B described hereinabove were best suited to control of static in the internal environment of this material and small amounts of these compounds were incorporated into these x-ray products.

As already indicated hereinabove, the charge control agents of the present invention can be incorporated into the surface whose charging is to be controlled in a number of fashions. In the instant case it was decided that overcoating the problem-causing gel sub layer with a thin coating of on the order of from about 0.2 to about 4 micrograms/cm of the charge control agent by deposition from a suitable solvent system such as ethyl alcohol provided most satisfactory results. Of equal success is the technique of mixing the charge control agent with the gel sub prior to coating thereof. When this latter technique was used, because the materials of group B are not strong surfactants, it was found necessary to increase the concentration thereof to a level of from about 0.5 to about 1.0 g/g of dry weight gelatin in order to obtain a sufficiently high surface concentration thereof to give the desired surface charging characteristics when the subbed base was impacted with stainless steel and/or anodized aluminum rollers. A third method for incorporating the charge control agent comprises contacting a solution thereof with the surface to achieve adsorption thereto and then removing any excess. This method was found most successful when the charge control agent solvent, for example lower alkanols such as methyl, ethyl, etc. alcohols, was, or incorporated, a swelling agent for the gelatin which opened the pores of the gel surface to permit penetration therein, thereby insuring (a) the formation of at least a discontinuous layer of the charge control agent at the surface of the gelatin; and (b) the secure attachment of this layer to the gel.

Preferred materials for this type of application are specified in the Examples presented below.

AERO FILM A second photosensitive product which has demonstrated an inordinately large degree of charging prob lems is aero film. The problems associated with these materials are due in large part to the peculiar external environment in which" they find use. These materials are used under extremely severe humidity conditions at extremely high altitudes and are required to advance at high speed through cameras whose component parts of rubber and plastic almost seem designed with the ulti' mate goal of generating as much static as possible on the film run through them.

In most of the aero film cameras, the rollers are either stainless steel, anodized aluminum, plated metals or several varieties of elastomeric materials, and static generated is due to the impacting of either the emulsion side or the rear surface of the film with the roller. Thus, the surface of the photosensitive product which must be modified is either the emulsion side which is generally overcoated with a protective layer of for example, gelatin plus a coating aid, and the backing layer which may include a slip agent and in present conventional materials a conductivity agent of the type described above.

In the modification of this type of product it was sought to incorporate a surfactant type of material to achieve the lowest possible bulk concentration of charge control agent in the emulsion overcoat and- /or backing layers. Thus, the materials of class A, described above, were selected as the primary candidates for use in this application, although members of each of the other classes could also be used.

Among the materials of class A which were preferred in this context were those wherein A (described above) was a partially or completely fluorinated carbon chain, Z is selected from the group consisting of 0 0 M ii and X is a halogen. The most useful member of this class and that which to date has demonstrated the strongest negative charging propensity while being readily available had the following formula:

and whose utility is indicated in the Examples below.

In the evaluation of photosensitive materials for use in aero film applications one becomes almost immediately aware of the limitations placed on any charge control system by the character of the external environment; i.e. a single film product may find use in as many as perhaps different cameras all of which have different roller surface, numbers of rollers, advance speeds, film orientations, etc. Since each of these variables modifies to some degree one or more of those characteristics which determine impact electrification (already described above) it becomes apparent that agents to compensate for other modes of charging by 10 bleeding off charges which if not bled off could result in the build up of a charge above the discharge threshhold levels. In such applications, it has therefore been found useful to combine the charge control agents of the instant application with conductivity agents to obl5 tain insurance against excessive charge build-up.

Although easily stated, the result is not always so easily defined in a given system, since conductivity agents like all other materials demonstrate their own peculiar impact electrification characteristics which must also be accounted for.

Mixtures of charge control and conductivity agents thus may be used to provide impact electrification values close to zero over a wider range of concentrations. Furthermore, combinations of two or more charge control agents may be used to achieve finer tuning of the surface charging characteristics of any given modified surface.

The following Examples will serve to better demonstrate the technique described above, a braod variety of useful charge control agents as well as radiation sensitive products incorporating charge control agents of the type described.

Table I EXAMPLE 1 A standard test surface is prepared by coating 7 mil poly(ethylene terephthalate) support with an unmodified overcoat of gelatin to a dry weight of l mg/ 2. Coated samples are conditioned to 5 percent RH 70F. A solution containing 1 mg/ml of the test compound in ethyl alcohol is prepared and one drop of this solution allowed to spread over 4 cm of the gelatin test surface. The resultant coverage of test compound on the gelatin surface is approximately 4 ug/cm This test area is then impacted with the metal test head (or other reference material) in the apparatus and with the technique described in the aforementioned Bailey patent and the charge generated is recorded. In some cases unsubbed poly(ethylene terephthalate) is used as a test substrate. The test values are recorded in Table I. It should also be noted that other solvents may be used in some cases for appropriate solvent action.

The values in Table 1 must be considered as relative values. The cleaning procedure for the impacting head may leave some surface contamination thus changing the magnitude of the charge generated on impact. Cleaning procedures have evolved over a period of time, however, and a much more repeatable surface is obtained by cleaning with appropriate solvent for the material previously tested followed by cleaning with absolute alcohol. Cleaning in this manner produces a value of approximately +30 esu/cm against the untreated gelatin check. Thus, the values in Table I must be compared with the appropriate charging value obtained for the untreated gelatin check measured in the same group of samples. These groups of samples are appropriately separated by a double space in the table 35 below.

Impact Charge Values for Treated Gelatin Against Various Reference Surfaces Esu/cm at 20 psi Impact Pressure Reference Surfaces No. Surface Treatment Solvent Metal Rubber Rem .let*** 1 Sodium p-Nitroso Phenol ETOH 3.4 7.5 1.1

p-Amino Benzoic Acid 3.1 +11.1 .4 3 p-Nitro Benzoic Acid -l9.2 3.3 Check, untreated gel. Avg. 5.9 +l2.6 3.5 4 Benzoic Acid ETOH 2.1 +1 1.4 3.2 5 2-4-6 Trinitro Benzoic Acid -28.8 -l5.3 5.4 6 Sodium Benzoate 5.1 8.7 .7 7 -Nitro Phenol 8.1 +10.2 3.2 8 icric Acid 24.7 1 1.3 3.0 9 Trinitro Resorcinol 36.0 13.7 4.0 Check, untreated gel, Avg. 3.5 +l2.l 4.5

10 p-Nitro Benzene Sulfonic Acid ETOH 32.0 -1 7.7 4.0 l l 3-Nitro Phthalic Acid 27.3 3.8 2.7 12 p-Nitro Cinnamic Acid l5.6 -14.l 5.6 Check, untreated gel Avg. 4.3 +12.4 4.1 13 Benzene Phosphonate, diH ETOH 2.6 +1 1.8 2.4 14 Ethyl diH Phosphate -l3.0 3.7 0 15 Butyl diH Phosphate -l2.5 1.2 0 l6 DibutylI-l Phosphate 1.3 O 0 Check, untreated gel, Avg. 6.8 +1 1.9 4.1 Carbon dispersion in cellulose acetate hexahydrophthalate Reference Surface No. Surface Treatment Solvent Metal Rubber 17 p-Nitro, NaBenzene Sulfonate ETOH 32.1 Check, untreated gel, Avg.

18 p-Nitrophenyl Acetonitrile ETOH .1 8.0 19 p-Nitrophenyl Acetic Acid -l3.4 1.9 20 p-Nitrophenoxy Acetic Acid 26.7 7.6 21 3-Nitrocha1cone .4 +1 1.5

Table l Continued Impact ('hnrge Values for "l'reuted (ielutin Against Various Reference Surfaces lisu/em' at psi Impact Pressure Reference Surfaces No. Surface Treatment Solvent Metal Ruhher Rem Jet*** Check, Avg. untreated gel 8.1 +l2.0

22 2.6-dinitro thymol ETOH 18.4 4.0 23 2.4-dinitro-1-naphthol-7- Sulfonic Acid 23.0 13.1 24 4-Nitrophthalic Acid 39.6 12.0 25 p-Nitrobenzarnide 4.3 .5 Check, Avg. untreated gel 9.2 +l0.5

26 2-4-6 Trinitro Benzene Sulfonic Aci ETOH -39.0 +7.1 Check. Avg. untreated gel 9.7 8.9 27 m-Nitro Sodium Benzene Sulfonate ETOl-l 29.0 6.0 Check, Avg. untreated gel 1 +l2.1 6.0

lmpact Charge For Treated Gel and Polyester Strips Esu/cm at 20 psi lmpactPressure Metal Reference No. Surface Treatment Solvent Gel Polyester** 28 p-Nitro B.S.A., dibutyl amine salt* ETOH 24.0 29 p-Nitro B.S.A., dibutyl amine salt PrCl 3.0 3O p-T.S.A.* ETOH -l8.6 -20.5 Check, Avg. untreated gel 8.1

31 4-Ch1oro m-Toluene NaSulfonate ETOH 3.0 3.0 32 p-Fluoro Sodium Benzene Sulfonate 22.0 14.0 33 p-Chloro Sodium Benzene Sulfonate 35.0 -22.0 34 p-Bromo Sodium Benzene Sulfonate -l0.0 8.5 Check, Avg. untreated gel and Mylar 35 2,5-dichloro B.S.A. ETOH 5.0 8.0 36 p-Hydroxy Sodium Benzene Sulfonate -22.0' -l5.5 37 o-(carboxy methoxy) Benzoic Acid 35.0 24.5 38 p-Hydroxy Benzoic Acid 30.0 -l0.0 Check, Avg. untreated gel and Mylar +10.0 .3 39 p-Chloro phenyl Acetic Acid ETOH l3.0 .6 40 4,4-Biphenyl disulfonic Acid -37.0 l8.0 41 2,5-Dichloro Sulfanilic Acid,

Na salt -l3.0 2.0 42 Sulfosalicylic Acid .0 -36.0 Check, Avg. untreated gel and Mylar The following abbreviations are used:

B.S.A. for Benzene Sulfonic Acid p-T.S.A. for p-Toluene Sulfonic Acid poly(ethylene terephthalate) 43 4-Sulfophthalic Acid, mono Na salt ETOH 25.0 -l6.0 44 2,2-Diphenic ACid l 1.0 3.0 45 Trimellitic Acid H -32.0 28.0 Check, Avg. untreated gel and Mylar +l0.0 .4 46 Benzene Sulfonic Acid ETOH 32.0 .4 47 B.S.A., didodecyl amine salt 3.2 2.0 48 Benzene Sulfonic Acid PrCl -22.0 1.2 49 B.S.A., didodecyl amine salt 3.7 2.4 Check, Avg. untreated gel and Mylar 9.5 .4 50 B.S.A.. dibutyl amine salt PrCl 3.0 1.1 51 p-T.S.A., tridodecyl amine salt ETOl-l 2.0 3.1 52 p-T.S.A., didodecyl amine salt 4.2 3.3 53 p-T.S.A.. tridodecy] amine salt PrCl 3.0 1.7 54 p-T.S.A., didodecyl amine sale 6.7 2.0 Check. Avg. untreated gel and Mylar +l3.0 .5 55 pT.S.A., triethyl amine salt ETOH +35.0 +35.0 56 4-Sulfophthalic Acid, dibutyl amine Salt 14.0 14.0 57 B.S.A. tridodecyl amine salt .8 .8 58 B.S.A., tridodecyl amine salt PrCl 3.0 1.5 59 B.S.A., tributyl amine salt MeOH +l4.0 +16.0 Check, Avg. untreated gel and Mylar, +10.5 .5

Metal Reference No. Surface Treatment Solvent Gel Polyester* 60 B.S.A., triethyl amine salt MeOH +1 1.0 2.2 61 p-T.S.A. triethyl amine salt 2.1 9.0 62 p-T.S.A., tributyl amine salt +23.0 8.5 Check, Avg. untreated gel and Mylar +1 1.0 .4 63 Pyromellitic Acid I MeOH 40.0 5.5 64 Terephthalic Acid +18.0 10.0 65 Phthalic Acid +20.0 4.0 66 Phthalic Acid I I ETOH -34.0 -l5.5 Check, Avg. untreated gel and Mylar +13.0 .6 67 Mellitic Acid MeOl-l 40.0 8.0 68 Citric Acid ETOH 32.0 69 Salicylic Acid 3.0 70 d-Tartaric Acid 33.0 -l6.0 71 Succinic Acid 14.0 10.0 72 Oxalic Acid 1.0 l2.0

Table I (ontinued Impact Charge Values for Treated Gelatin Against Various Reference Surfaces Esu/cm at 20 psi lmpact Pressure 1 Reference Surfaces No Surface Treatment Solvent Metal Rubber Rem .let*** 73 Malonic Acid +l2.5 7.0 74 Malic Acid 16.0 4.0 75 Maleic Acid l9.0 l4.0 76 Adipic Acid 60 4.0 77 Fumaric Acid 16.0 2.5 78 Hydroquinone 1.0 9.0 79 Glutaric Acid 1.6 8O L-Tartaric Acid 40.0 -24 81 50-50 D, LTartaric Acid ETOH 46.0 82 Pyromellitic Acid, Mono Na Salt 15.0 83 1,3-dicarboxymethyl--Na bcnzenesulfonate 1.6 4.0

I Treated Sub Strip 84 Pyromellitic Acid N11 pH 4.3 1% in H O 4.0 85 Pyromellitic Acid Nl-L, pH 8.2 +l3.0

Treated Sub Strip 86 Mellitic Acid 60 MeOl-l- 1.4

H 0 87 Citric Acid MeOH 1.8 88 Citric Acid MeOH- .6

4O H 0 89 d-Tartaric Acid MeOH .25 90 d-Tartaric Acid 60 MeO1-1 .4

40 H 0 91 Pyromellitic Acid aMeOH .9

40 H 0 92 5-Sulfoisophthalic Acid Na salt MeOH 7 0 93 S-Sulfosalicylic Acd MeOH 1.2 poly(ethylene terephthalate) Several of the test materials are also applied from wa- 35 Table 11 ter. The molecular size of many of the simpler compounds no doubt allows them to be absorbed into the Simulated Gel Wash Test a swollen gelatin coating since it contains no hardener. 20 PSI Impacts 70 F Stainless Steel Reference Head Some materials may also be imbibed mto the surface values in ESU/CM on Treated Gel Nitrate Subs during longer periods of time at conditions of high rela- 0 V G A R tive humidity which allows considerable swelling of the Agent gem mm :2 gelatin coating. Thus, these materials are no longer present at the surface (unless they are surface active NOne untreflted Sub check +22) materials) and the surface is now characteristic of an None Untreated Type V gel check +110 untreated gelatin.

EXAMPLE 2 spread or coated by hand on cellulose acetate propionate (14 percent propionyl, 30 percent acetyl plasticized with butyl sebacate), also subbed with a conventional gel-nitrate solution (1 percent gel, /2percent cellulose nitrate [11 percent N 2 percent acetic acid balance methanol and acetone), as a simulated gel wash. The charging values are shown in Table 11. g

94 S-Sulfosalicylic Acid Pyromellitic Acid Tamol N Mellitic Acid Citric Acid Saponin Tie $93. Nee, b-b

Inspection of these values shows a considerable reduction 'in the high positivecharging behavior of gelatin.

' EXAMPLE 3 A machine coating is made from the data of Example 2 to control average and investigate other reference surfaces and other humidities. The coating solutions v,cortsist of:

f 1 percent and 1.5 percent Pyromellitic acid (PMA) 1 percent Type V gel The PMA and gel check also contain 0.19 percent Saponin as a coating aidfThe five solutions are coated by conventional hopper application at a). 123, and b) 154 cc solution per ft coverages on both cellulose tri- 25 acetate (41 percent acetyl) and cellulose acetate propionate (14 percent propionyl. 30 percent acetyl) support. subbed with a mixed gel-nitrate sub. The samples are then impacted with two reference surfaces. stainsolution of polyethylene pyromellitate in 60 parts methyl alcohol and 40 parts water is coated over the gelatin sub of cellulose triacetate support at a coverage ofapproximately 4 ag/cm an impact charging value of less steel and rem jet. The values are shown in Table 111. +0.2 esu/Cm is obtained at psi impact and 5 percent The charging yalues for both sets of experimental sam- The a ging Value or th n eate ample u der ples are identical. identical conditions is esu/cm'-.

Table Ill Gel Wash Coatings On Cellulose Acetate Propionatc Gel Nitrate Sub (Described Above) ESU/CM2 On Sub Against Metal and Rem .lct* 2t) PSl Single Sided Impacts 5%, 15% 50% Sample 5% Rem Rem Rem N0. Feature Coverage Metal Jet* Jet* Jet* 22 Sub cheek-uncoated +30 0 +5.9 +5.5 +5.8 1 Check 1'7! Type V Gel 123 3.8 +3.2 +3.7 +3.6 2 Check l7( Type V Gel l54 2.0 +2.4 +2.9 +3.4 7 1% Gel 1% PMA 123 1.2 .52 +1.1 .87 6 1% Gel+ l7r PMA 154 2.0 .5 .8 .4 9 1% Gel l.5% PMA 123 f 2.0 i ,52 '.l .5 l0 1% Gel 1.5% PMA 154" 3.2 .2 1 .03 ,4 1e 1% GE1 1% Sap. 123 2.0.. +1.4 +2.4 +3.2 14 1% Gel 1% Sa 154 +1.0 +1.2 +2.1 +2.7 18 1% Gel 1.5% up. 123 .3 +1.3 +2.0 +2.6 20 1% Gel 1.5% Sap. 154 1.0 +1.1 +2.4 +2.0

*earhon dispersion in cellulose acetate hcxahydrophilialate J i U Inspection of Table III shows PMA is clearly more ef- The charging properties of gelatin may be modified fective than Saponin and is relatively invariant of the by chemical reaction of the gelatin. Representative humidity range whereas Saponin shows a positive trend 3O modifications are shown in Examples 5 and 6. (less effective) with humidity. The lower values ob- EXAMPLE 5 tained for check samples 1 and 2 are the result of 0. 19 percent Saponin used as a coating aid. T'wenty gm. of acid process gelatin is dissolved in 100 ml water and 100 ml DMF added. The solution is EXAMPLE 4 heated to 80C and 5.0 gm. B-Propiolactone is added Many of the smaller organic molecules of Example 1 with vigorous mixing. The temperature is maintained are easily imbibed into a gelatin surface if they are apfor one-halfhour, the contents cooled, and precipitated plied from aqueous media due to the swelling of the into a 1:1 mixture by volume of acetone-methyl alcogelatin. Thus the resultant charging properties of the hol. The precipitate is then extracted with 3A alcohol surface may be difficult to control. A large molecule 40 in a Waring blender and finally triturated overnight incapable of excessive imbibition yet retaining the in with 3A alcohol, filtered, and dried. The dry yield is herent charging properties is prepared as follows: A co- 24.9 gm. polyester (polyethylene pyromellitate) is p pa e y The chemically modified gelatin is soluble in water. mixing in a suitable flask equimolar amounts of ethyl- A 6 percent solution forms a gel at room temperature. ene glycol and pyromellitic dianhydride with sufficient A 6 percent l i coated 3 mil wet thickness over m hy m H Provide 21 0 g subbed cellulose triacetate produces a dominant surneous solution at C. The temperature is then raised face of modified gelatin. The impact charge value of to C and DMF distilled Off under a vacuum. Heating this surface is +6 esu/cm The charging value of the is continued under vacuum ultil the temperature of the subbed cellulose triacetate is +30 esulcm contents reaches C. This temperature is main- 50 tained for approximately one hour. i I 1 EXAMPLE 6 A viscous off-white polymer remains which upon Another chemically modified gelatin with modified cooling solidifies into a glassy mass. The polymer is charging properties is prepared as follows: hard and brittle, dispersible in water, and soluble in di- Forty gm. acid process gelatin is slurried in 250 mls lute alkali. '55 dry DMF. To this, 19.2 gm (0.1 mole) trimellitic anhy- Polyethylene pyromellitate may be coated from dride (TMA) dissolved in 50 ml DMF is added. The aqueous solutions over gelatin with retention of the mixture is thermostatted at 50C with mixing for a penegative charging characteristic of the molecule. A l riod of 30 hours during which time the gelatin reaction percent aqueous solution coated on the geleatin sub of product gradually dissolves to produce a homogeneous a cellulose acetate support (43.3 percent acetyl, plasti- 0 solution. The solution is cooled and precipitated into cized with methoxyethyl phthalate and triphenyl phos- 1,500 ml isopropyl alcohol. Subsequent washing with phate) produces a charging value of-33 esu/cm 20 psi isopropyl alcohol and drying yields 50.1 gm or 84 6 impact at 5 percent RH. percent of the theoretical amount. The remainder is Mixtures of gelatin and polyethylene pyromellitate lost due to solubility in the isopropyl alcohol-DMF mixcan be prepared substantially as described in Example 5 ture,

3. Charging values anywhere between that of pure gela- .tin (ca. +30 esu/c m and ,that of pure polyethylene The product has limited water solubility but is dispersible in water. Coatings made from a 6 percent dispersion produce a matte coating. A 6 percent dispersion has a pH of approximately 2.

Upon addition of alkali to a pH of approximately 4 a clear solution results.

The impact charging values of this material depend 20 psi impact pressure. The results are shown in Table V below.

upon the state of the carboxyl groups on the modified TABLE V gelatin. In the free carboxyl form the material is less 5 h positive charging than unmodified gelatin. however. as W (hmgmg i f' ?"l,, 2 flumc'drhm the carboxyl groups are neutralized with various alkalies the charging properties more closely resemble (\mccmffllimt lmpflcl chflfgins I gin/lb of melt Coverage A Coverage B those of unmodified gelatin. Six percent solutions of TMA modified gelatin are coated over cellulose triace- 2 +335 l. .5 22. tate at various pH s and impact charging measured at 1:3 1 2 20 psi and percent RH. The results are shown in (W03 uni +is.u +135 Table IV below. Um i 75 0.03 -l0.l) -2in TABLE IV (m4 -l0.7 :9.u

Coverage A equals 175 cc solution per [U0 ft lmpucl Coverage B equals 350 cc solution per 100 ft Value pH Alkali esu/cm 7 Inspection of Table V will show that the two different 2 None +14 thicknessesare zero charging at 0.025 and 0.015 gm 4 NUOH per lb. for A and B respectively. Coverage B is within 4 NHQH H6 the 0 8 esu/cm in the concentr ti r f 0 O l 2 8.5 NH OH +i9 a ange unmodified gelatin +30 to 0.02 gm per lb.

The reduction of positive charging of gelatin by the above chemical modifications is not sufficient to eliminate static completely, but is only intended to show representative chemical modification with active negative charging groups on the gelatin backbone. Other negative charging groups could be introduced which might be more effective. A chemically modified gelatin is of value however. Mixtures of a chemically modified gelatin with a negative charging material to reduce charging close to zero requires a smaller amount of ad denda. This is of particular value if the addenda is sensitometrically active or very costly and can only be used in limited concentrations.

Although the principal subject of surface modification described in the foregoing examples is gelatin, it should be clear that since all materials demonstrate triboelectric effects to one degree or another that virtually any charging surface can be modified with an appropriate agent to produce desired surface charging characteristics.

EXAMPLE 7 A suitable support poly(ethylene terephthalate), cellulose ester, etc.) is first coated withan unmodified 5 percent gelatin solution at a wet coverage of 615cc per hundred square feet. This gelatin coating provides" an isolating layer over which the subsequently prepared experimentally modified gelatin can be coated. A 2.9 percent solution of gelatin is prepared using low concentrations of a fluorinated surfactant having the formula Me N Me 7 I and this modified gelatin solution simultaneously overcoated at a wet coverage of 17600 per hundred square feet. The samples are then equilibrated at 5 percent RH, 70F for the impact electrification measurements. lmpact values are measured at 5 percent RH, 7()-F and Coatings of other materials tested in a fashion similar to that just as described are shown in Table VI below wherein the concentration of the additives is in percent by weight and the coverage is Coverage A. 10 PSI, 5 percent RH, 70F).

' TABLE VI i C7Hl5 CONH(CH2)3 N\-Me I C H CONll-(CH ii Me 1 ,Me C H cows-(c11 N MQ I on 0 ii I $3 0 ii =c H -o-P-oi+ on c H EXAMPLE 8 As alluded to hereinabove, mixtures of surface active agents may be used to provide impact electrification values close to zero over a wider range of concentra tions.

. .29 This is'illustrated in Table VII below using a Saponinfluorocarbon reactant. mixture.

Impact electrification values at 10 psi impact pressure, percent RH, 70F arev as follows?- EXAMPLE 9 A similar result is observed in the treatment of the x-ray materials described above, although such dual 5 protection is not necessarily so important with that type TAB E of product in view of the relatively controlled external r and internal environment of these products. p? electrification saponin'flumocarbon Coatings of the xray subbing layer are made in con- Surfactant Mixtures 0 vent onal coating apparatus to 1nvest1gate suitable condpluowca'rboni gaponin Concentration centrations of charge control agents and mixtures "F i 1 -g thereof. A conventional gel subbing layer, is used exb rj 'eu: 0 9 clusive of the conducting salt.

' 0m l The sub s normally composed of one per cent gelaj 7 t1n, Sapomn, a fung1c1de, a hardener, for example 0.08 1 '1.5 chrome alum and matte.

X The effect of Saponin additions to the subbing composition is shown in Table VIII below: Comparison of Tables. V and VII shows the expansion of effectw e work ng concentratlons for the fluorocar- TABLE VI bon by uslng a m1xture of charge control agents and "coatingaids. With these types of combinations of mateimpaq El trifi ti n or Modified s bbin Layers rials the charging characteristics of a particular surface 5161 *f i-1' PSI Impact Pressure, F can be very-narrowly and spec1fically controlled. I

The use of the more common anionic surfactants, Tmul RH RH i I Sample 70 Saponin Anodized Anodized 1.e., alkyl aryl polyoxyethylene sulfonate salts and triso- 30 No. Addendum ss Alumi- SS Aluminum pr'opyl naphthalene sulfonate sodium salt have become commonplace in the photographic industry to control i 0 2.5 +260 2 .01 +240 +11.0 +220 +12.7 coatmg problems, however, they contrlbute strongly to 3 5 59 60 34 24 1 4 .20 2.0 3.5 0.3 1.0 the static marklng of film products. The use of fluoro- 5 25 L6 +22 carbon mixtures withthe more common surface act1ve 35 6 .30 3.0 .8 5.0 3.2

Convent1onal x-ray agents and coating aids allows the manufacturer to conproduct +1645 73 trol the static charging properties of any coated surface w' in whatever limits are nece"sar It also allows the f h b bl f t y d lnspectlon of Table VIII 1nd1cates that the hlgher use 0 t e est a 6 sur ac 9 as Goa mg S 40 concentrations of Saponin could be used successfully Such thatthe qualty of the coatmg not compromlsed to lower the charging characteristics of the sub. Howto control static. ever, at concentrations of 0.25 per cent or above there Many other combinations of surface active agents are indications of destruction of good bonding propermay be employed in subbing layers, backing layers, 45 1165 P the emulslon f y emulsion layers and in coatings over emulsion layers to Mlxtul'es of Saponm and p'chlorobenzene Sulfonlc t l the char in r0 erties of these individual la ac1d sodium salt, p-CSA, Na Salt, were used as the subcon to g g p p y bing addenda and coated and tested as above. These ers and the Inmate product" results are shown in Table IX below.

TABLE IX Impact Electrification of Modified Subbing Layers vs Stainless Steel and Anodized Aluminum at 20 psi Per Cent Addenda 5% RH 50% RH p-CSA, Anodized Anodized Sample No. Saponin Na Salt SS Alumi- SS Aluminum I'IUITI 7 .01 .4 9.0 22.0 9.0 8 .01 .45 7.2 2.6 25.0 l0.0 9 .01 .5 0.5 6.5 -27.0 -13.3 10 .10 .45 +l3.8 +9.0 8.0 -5.4 11 .10 .50 +5.0 2.5 8.0 1.2 12 .10 .60 5.0 --I.2 -Il.7 5.0 l3 .10 .70 5.0 -2.5 I0.0 5.0 14 .13 .50 +5.3 +1.2 11.4 +6.0 15 .15 .50 2.6 +1.0 12.0 8.0 16 .18 .50 +5.4 +0.8 6.0 4.0 17 .13 .60 -4.2 -5.1 l4.4 -8.5 18 .15 .60 "-5.6 4.9 -14.0 7.0 19 .18 .60 2.5 -4.5 -9.0 -4.5 Check +105 7.3

Inspection of Table IX indicates four mixture concentrations which meet a general criteria of zero i 10 esu/cm under all conditions tested. Further inspection shows that ten of the mixture concentrations meet a general criteria of zero 1 vl esu/cm against the anodized aluminum roll surface in both humidity ranges. It should also be noted that where Saponin which is generally recognized as a coating-aid as used in combination with a charge control agent, a better handle for controlling the charging characteristics of the surface is obtained since narrower variations in charging behavior are experienced with similar quantitative additions of charge control agent.

EXAMPLE Two production coatings of Saponin p-chlorobenzene-sulfonic Acid Sodium Salt (p-CSA, Na Salt) are used as addenda in subbing mixtures and coated. Full width samples are processed and examined for static defects.

In Trial 1 the emulsions are coated in the normal manner, i.e., one side is emulsion coated and dried then the other side is emulsion coated in line and dried.

ln Trial 2 the first emulsion is coated and dried and put through to windup. The roll is then sent through the machine a second time to emulsion coat the opposite side. Thus, Trial 2 is a much more severe test of the electrostatic sparking propensity of the sub layer.

The results are shown in Table X below:

TABLE X Four full length production rolls are coated with the preferred composition of 0.2 percent Saponin 0.45 percent pCSA, Na Salt as addenda in the sub. The impact electrification values of these four rolls are shown in Table XI below:

Table x1 Production Rolls of Saponin p-CSA, Na Salt Addenda to Poly(ethylene terephthalate) Sub (Gelatin Plus Matte, Fungicide, Etc.)

Impact Electrification 5% RH RH Sample SS MHC SS MHC l l0.0 6.4 20.0 8.4 2 9.1 -l0.2 20.0 7.5 3 5.4 6.3 23.0 7.6 4 9.0 7.0 20.0 7.5

Production Trials of Saponin (p-C.S.A., Na salt) Addenda to poly( ethylene terephthalate) subs Impact Electrification of Sub 5% RH 50% RH Anodized Anodized Addenda SS Alumi- SS Alumi- Static Results num num 0.2% Saponin Trial 1 5.5 5.4 +l3.0 5.7 Scattered Branch 0.0% pstatic 30 ft. only chlorobenzenesulfonic remainder clear Acid Sodium Salt no static Trial 2 5.5 +l2.5 Branch static from roller grooves, some spot static throughout 0.% Saponin Trial 1 8.5 9.5 +160 6.0 Scattered spot static 0.45% p-CSA Na Salt Trial 2 +1 1.0 +l0.0 Spot static throughout 0.2% Saponin Trial 1 +120 9.0 +23.0 8.4 No static marking 0.45% p-CSA Na Salt Trial 2 +l5.0 +l8.5 Slight static, branch an spot for 30 feet Check Trial 1 +23.0 +l2.2 +24.0 +l4.0 No static marking Trial 2 Spot static throughout Trial 2 Dense branch throughout Inspection of Table X shows that the 0.2 percent Saponin 0.45 percent p-CSA Na Salt is superior to all other coatings. The most severe test, Trial 2. shows this sample to be the only one which is static free throughout the roll except for approximately 30 feet at the beginning of the sample.

A further review of Table IX will show that there is sufficient room for adjustment of concentration to reduce charging very close to zero.

Additions of p-CSA, Na Salt to subbing formulations at IX and 10X use concentrations have shown no adverse sensitometric effects on accelerated testing.

Although the foregoing description relates primarily to testing and treatment of gel subbed and unsubbed polymeric film base materials it should be clear that the techniques and principles disclosed herein are equally applicable to other materials which demonstrate undesirable triboelectric effects. For example, resin coated paper products which find broad usage in the photographic arts can be similarly tested and the various surfaces thereof treated in accordance with the techniques described herein. Subbing layers applied over such bases may also be treated as may emulsions, non-silver, and therefore nongelatin, photosensitive products, etc.

Futhermore, although the description contained herein has been directed primarily to the addition of relatively high negative charging species to surfaces which demonstrate relatively high positive charging when impacted with a given reference surfaces which forms a greater portion of that surfaces internal and/or external environment, positive charging charge control agents of which there are many which can be analyzed using the techniques described herein, can be similarly utilized to increase or decrease their charging propensities by the addition of less negative, positive or yet more highly positive charging charge control agents.

The relative amounts of charge control agent which are imbibed into, coated on or intermixed with the surface to be modified will of course depend on many of the numerous factors discussed hereinabove which af feet the charging of the system under consideration.

From the foregoing examples several points concerning the systems under discussion and the solutions and techniques proposed for use in connection therewith should be clear. Among these are the following:

1. The static charging properties of surfaces are apparently a direct consequence of their chemical struc tures. In particular the strong positive charging characteristics of gelatin and gel-nitrate subs as utilized in photographic applications can be neutralized or nullified by the application of any one of a number of negative charging materials out of a suitable solvent or in some other manner to form a continuous or discontinuous layer having a dry thickness of less than about 301 Angstroms.

2. The effect of this technique is coverage dependent thereby providing a handle with which the charging or surface potential can be adjusted to any desired level.

3. The charging properties of any given unmodified surface, a surface of a charge control agent or a surface modified with a charge control agent are impossible to predict with any degree of certainty and thus, if one de sires to alter the charging characteristics of any particular surface it is necessary to first accurately measure the charging characteristics of the unmodified surface, evaluate a series of charge control agents to determine their charging propensities, select from among the agents evaluated and then incorporate varying amounts of same into the surface to be modified until the desired charging level and polarity is achieved. Such a tech nique is necessary even within certain homologous groups of charge control agents since structurally very closely related materials frequently demonstrate quite different charging propensities as shown in Example 1. Thus, any realistic approach to the solution of the surface charging problem must, for the present at least, involve the practice of the method of the present invention.

Futhermore, although, in the discussion and examples presented hereinabove substantially all of the techniques described for overcoming the problem of static charging have been directed to the treatment of, for example, the photographic film or more broadly the impacting surface it must be made clear that similar results can be achieved by treatment of the impacted surface, ie., for example, in the case of aero film the camera roller or in an emulsion coating machine the stainless steel or anodized aluminum roller. Such treatment can be accomplished by impregnating into or coating onto the surface of such roller charge control agents which produce a substantially zero, or very low charge when impacted with, for example, a gel subbed film support, or the emulsion or support side of a specific photosensitive material.

Stated more generally, as described at the beginning of this application the generation of triboelectric charges is due to the contacting and dissociation of two usually dissimilar surfaces. What is being stated now is that either or both of these surfaces may be treated to reduce triboelectric charging to an acceptable level. Thus, in the case of the charging problem incident to the use of aero film, it would be entirely possible to coat or impregnate the camera transport rollers with a suitable charge control agent to achieve charge reduction.

As should also be clear from the foregoing description the quantities and concentrations of charge control agents which are used to alter the charging characteristics of surfaces will vary broadly depending upon the nature of the charging surface and may range from a discontinuous spotty layer up to and including continuous layers of charge control agents which demonstrate, to a large extent, the charging characteristics of the charge control agent.

The silver halide emulsions used in the photographic products of the present invention can comprise, for example, silver chloride, silver bromide, silver bromoiodide, silver chlorobromide, silver chloroiodide, silver chlorobromoiodide crystals or mixtures thereof. The emulsions may be coarse or fine grain emulsions prepared by any of the well-known techniques, e.g., single jet emulsions such as those described in Trivelli and Smith The Photographic Journal, Vol. LXXiX, May, 1939 pp 330-338), double jet emulsions such as Lippmann emulsions, ammoniacal emulsions, thiocyanate or thioether ripened emulsions such as those described in Neitz et al. U.S. Pat. No. 2,222,264 issued Nov. 19, 1940; Illingsworth U.S. Pat. No. 3,320,069 issued May 16, 1967; and McBride U.S. Pat. No. 3,271,157 issued Sept. 6, 1966. Surface image emulsions may be used or internal image emulsions may be used such as those described in Davey et al. U.S. Pat. No. 2,592,250 issued May 8, 1952; Porter et al. U.S. Pat. No. 3,206,313 issued Sept. 14, 1965', Berriman U.S. Pat. No. 3,367,778 issued Feb. 6, 1968; and Bacon et al. U.S. Pat. No. 3,447,927 issued June 3, 1969. If desired, mixtures of surface and internal image emulsion may be used as described in Luckey et al. U.S. Pat. No. 2,996,382 issued Aug. 15, 1961. The emulsions may be regular grain emulsions such as the type described in Klein and Moisar, J. Phot. Sci., Vol. 12, No. 5, Sept./Oct., 1964, pp 242-251. Negative type emulsions may be used or direct positive emulsions may be used such as those described in Leermakers U.S. Pat. No. 2,184,013 issued Dec. 19, 1939; Kendall et al. U.S. Pat. No. 2,541,472

issued Feb. 13, 1951', Berriman U.S. Pat. No. 3,367,778 issued Feb. 6, 1968; Schouwenaars British Pat. No. 723,019 issued Feb. 2, 1955;1llingsworth et al. French Pat. No. 1,520,821 issued March 4, 1968', 111- ingsworth U.S. Pat. No. 3,501,307 issued Mar. 17, 1970; Ives U.S. Pat. No. 2,563,785 issued Aug. 7, 1951; Knott et al. U.S. Pat. No. 2,456,953 issued Dec. 21, 1948; and Land U.S. Pat. No. 2,861,885 issued Nov. 25, 1958.

The emulsions used with this invention may be sensitized with chemical sensitizers, such as with reducing agents; sulfur, selenium or tellurium compounds; gold,

platinum or palladium compounds; or combinations of these. Suitable procedures are described in Sheppard et al. U.S. Pat. No. 1,623,499 issued Apr. 5, 1927; Waller et a1. U.S. Pat. No. 2,399,083 issued Apr. 23, 1946; McVeigh U.S. Pat. No. 3,297,447 issued Jan. 10, 1967; and Dunn U.S. Pat. No. 3,297,446 issued Jan. 10, 1967.

The silver halide emulsions used with this invention may contain speed increasing compounds such as polyalkylene glycols', cationic surface active agents and thioethers or combinations of these as described in Piper U.S. Pat. No. 2,886,437 issued May 12, 1959; Dann et al. U.S. Pat. No. 3,046,134 issued July 24, 1962; Carroll et al. U.S. Pat. No. 2,944,900 issued July 12, 1960; and Goffe U.S. Pat. No. 3,294,540 issued Dec. 27, 1966.

The silver halide emulsions used in the practice of this invention can be protected against the production of fog and can be stabilized against loss of sensitivity during keeping. Suitable antifoggants and stabilizers each used alone or in combination include thiazolium salts described in Brooker et al. U.S. Pat. No. 2,131,038 issued Sept. 27, 1938; and Allen et a1 U.S. Pat. No. 2,694,716 issued Nov. 16, 1954; the azaindenes described in Piper U.S. Pat. No. 2,886,437 issued May 12, 1959; and Heimback et a1. U.S. Pat. No. 2,444,605 issued July 6, 1948; the mercury salts as described in Allen et al. U.S. Pat. No. 2,728,663 issued Dec. 27, 1955; the urazoles described in Anderson et al. U.S. Pat. No. 3,287,135 issued Nov. 22, 1966; the sulfocatechols described in Kennard et al. U.S. Pat. No. 3,236,652 issued Feb. 22, 1966, the oximes described in Carroll et al. British Pat. No. 623,448 issued May 18, 1949; nitron; nitroindazoles; the mercaptotetrazoles described in Kendall et al. U.S. Pat. No. 2,403,927 issued July 16, 1946; Kennard et a1 U.S. Pat. No. 3,266,897 issued Aug. 16, 1966; and Luckey et al. U.S. Pat. No. 3,397,987 issued Aug. 20, 1968; the polyvalent metal salts described in Jones U.S. Pat. No. 2,839,405 issued June 17, 1958; the t'niuronium salts described in Herz et a1. U.S. Pat. No. 3,220,839 issued Nov. 30, 1965; the palladium, platinum and gold salts described in Trivelli et al. U.S. Pat. No. 2,566,263 issued Aug. 28, 1951; and Yutzy et a1 U.S. Pat. No. 2,597,915 issued May 27, 1952.

The photographic and other hardenable layers used in the practice of this invention can be hardened by various organic or inorganic hardeners, alone or in combination, such as the aldehydes, and blocked aldehydes as described -in Allen et al. U.S. Pat. No. 3,232,764 issued Feb. 1966, ketones, carboxylic and carbonic acid derivatives, fulfonate esters, sulfonyl halides and vinyl sulfonyl ethers as described in Burness et a1. U.S. Pat. No. 3,539,644 issued Nov. 10, 1970, active halogen compounds, epoxy compounds, aziridines,

active olefins, isocyanates, carbodiimides, polymeric hardeners such as oxidized polysaccharides like dialdehyde starch and oxyguargum and the like.

The photographic emulsions and elements described in the practice of this invention can contain various colloids alone or in combination as veh cl s, binding agents and various layers. Suitable hydrophilic materials include both naturally-occurring substances such as proteins, for example, gelatin, gelatin derivatives, cellulose derivatives, polysaccharides such as dextran, gum arabic and the like; and synthetic polymeric substances such as water soluble polyvinyl compounds like poly(- vinylpyrrolidone), acrylamide polymers and the like.

The described photographic emulsion layers and other layers of a photographic element employed in the practice of this invention can also contain alone or in combination with hydrophilic, water permeable colloids, other synthetic polymeric compounds such as dispersed vinyl compounds such as in latex form and particularly those which increase the dimensional stability of the photographic materials. Suitable synthetic polymers include those described for example, in Nottorf U.S. Pat. No. 3,142,568 issued July 28, 1964; White U.S. Pat. No. 3,193,386 issued July 6, 1965; Houck et al. U.S. Pat. No. 3,062,674 issued Nov. 6, 1962; Houck et al. U.S. Pat. No. 3,220,844 issued Nov. 30, 1965; Ream et al. U.S. Pat. No. 3,287,289 issued Nov. 22, 1966; and Dykstra U.S. Pat. No. 3,411,911 issued Nov. 19, 1968. Particularly effective are those water-insoluble polymers of alkyl acrylates and methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates, those which have cross-linking sites which facilitate hardening or curing described in Smith U.S. Pat. No. 3,488,708 issued Jan. 6, 1970, and those having recurring sulfobetaine units asdescribed in Dykstra Canadian Patent 774,054.

The photographic elements used with this invention may in addition to the charge control agents described contain conducting layers, or compounds which may comprise soluble salts, e.g., chlorides, ni' trates, etc., evaporated metal layers, ionic polymers such as those described in Minsk U.S. Pat. No. 2,861,054 issued Nov. 18,1958 and Sterman et al. U.S. Pat. No. 3,206,312 issued Sept. 14, 1965, or insoluble inorganic salts such as those described in Trevoy U.S. Pat. No. 3,428,451 issued Feb. 18, 1969.

The photographic layers and other layers of a photographic element employed and described herein can be coated on a wide variety of supports in addition to those mentioned specifically above. These include cellulose nitrate film, poly(vinyl acetal) film, polystyrene film, and related films or resinous materials, as well as glass, paper, metal and the like. Typically, a flexible support is employed, especially a paper support, which can be partially acetylated or coated with baryta and/or an alpha-olefin polymer, particularly a polymer of an alpha-olefin containing 2 to 10 carbon atoms such as polyethylene, polypropylene, ethylenebutene copolymers and the like.

As alluded to above, the radiation sensitive layers employed in the practice of this invention may contain surfactants such as saponin; anionic compounds such as the alkyl aryl sulfonates described in Baldesiefen US, Pat. No. 2,600,831 issued June 17, 1952; amphoteric compounds such as those described in Ben-Ezra U.S. Pat. No. 3,133,816 issued May 19, 1964;'and water soluble adducts of glycidol and an alkyl phenol The photographic elements employed in the practice of this invention may contain matting agents such as starch, titanium dioxide, zinc oxide, silica, polymeric beads including beads of the type described in Jelley et a1. U.S. Pat. No. 2,992,101 issued July 11, 1961 and Lynn U.S.Pat. No. 2,701,245 issued Feb. 1, 1955; and alkali soluble polymeric particles of the type described in Jelley et al U.S. Pat. No. 2,992,101.

' The photographic layers used in the practice of this invention may be coated by various coating procedures including dip coating, air knife coating, curtain coating, or extrusion coating using hoppers of the type described in Beguin U.S. Pat. No. 2,681,294 issued June 15, 1954. If desired, two or more layers may be coated simultaneously by the procedures described in Russell U.S. Pat. No. 2,761,791 issued Sept. 4, 1956; Hughes U.S. Pat. No. 3,508,947 issued Apr. 28, 1970; and Wynn British Pat. No. 837,095 issued June 9, 1960.

This invention may be used with elements designed for colloid transfer processes such as described in Yutzy et a1. U.S. Pat. No. 2,716,059 issued Aug. 23, 1953; silver salt diffusion transfer processes such as described in Rott U.S. Pat. No. 2,352,014 issued June 20, 1944; Land U.S. Pat; No. 2,543,181 issued Feb. 27, 1951; Yackel et al. U.S. Pat. No. 3,020,155 issued Feb. 6, 1962; and Land U.S. Pat. No. 2,861,885 issued Nov. 25, 1958; color image transfer processes such as described in Rogers U.S. Pat. Nos. 3,087,817 issued Apr.

1965; and

1963; 3,185,567 issued May 25, 2,983,606 issued May 9, 1961; Weyerts et a1. U.S. Pat. No. 3,253,915 issued May 31, 1966; Whitmore et a1 .U.S. Pat. No. 3,227,550, issued Jan. 4, 1966; Barr et a1.

U.S. Pat. No. 3,227,551 issued Jan. 4, 1966; Whitmore et al U.S. Pat. No. 3,227,552 issued Jan. 4, 1966; and Land U.S. Pat. Nos. 3,415,644 issued Dec. 10, 1968; 3,415,645 issued Dec. 10, 1968; and 3,415,646 issued Dec. .10, 1968; and imbibition transfer processes as described in Minsk U.S. Pat. No. 2,882,156 issued Apr. 14, 1959.

This invention may be used in elements designed for recording print out images as described in Fallesen U.S. Pat. No. 2,369,449 issued Feb. 13, 1945 or Bacon et a1. U.S. Pat. No. 3,447,927 issued June 3, 1969; direct print images as described in Hunt U.S. Pat. No. 3,033,682 issued May 8, 1962 and McBride U.S. Pat. No. 3,287,137 issued Nov. 22, 1966; elements designed for processing by heat as described in Sorensen et a1. U.S. Pat. No. 3,152,904 issued Oct. 13, 1964; Morgan et al U.S. Pat. No. 3,457,075issued July 22,1969; Stewart ct al"U.S. Pat. No. 3,312,550'issued Apr. 4,

.1967; Colt U.S. Pat. No. 3,418,122 issued Dec. 24,

1968; Yutzy et al. U.S. Pat. No. 3,392,020 issued Feb. 8, 1965; Humphlettet al. U.S. Pat. No. 3,301,678 issued Jan. 31, 1967; and Haist et a1. U.S. Pat. No.

' sued Jan. 4, 1955; Barr et a1. U.S. Pat. No. 3,227,554 issued Jan. 4, 1966; Graham et al. U.S. Pat. No.

3,046,129 issued July 24, 1962; Vittum et al. U.S. Pat. No. 2,360,290 issued Oct. 10, 1944; and Thirtle et a1. U.S. Pat. No. 2,701,197 issued Feb. 1, 1955', or elements to be developed in solutions containing colorforming couplers such as those described in Mannes et al. U.S. Pat. No. 2,252,718 issued Aug. 19, 1941; Car roll et al. U.S. Pat. No. 2,592,243 issued Apr. 18, 1952; and Schwan et al. U.S. Pat. No. 2,950,970 issued Aug. 30, 1966; and in false-sensitized color materials such as those described in Hanson U.S. Pat. NO. 2,763,549 issued Sept. 18, 1956.

Photographic elements prepared according to this invention can be processed by various methods including processing in alkaline solutions containing conventional developing agents such as hydroquinones, catechols, aminophenols, 3-pyrazolidones, phenylenediamines, ascorbic acid derivatives, hydroxylamines, hydrazines, reductones and the like; web processing such as described in Tregillus et a1. U.S. Pat. No. 3,179,517 issued Apr. 20, 1965; stabilization processing as described in Russell et al. Stabilization Processing of Films and Papers," PSA Journal, Vol. 168, August, 1950; monobath processing as described in Levy Combined Development and Fixation of Photographic Images with Monobaths, Phot. Sci and Eng, Vol. 2, No. 3, October, 1958, and Barnes et a1. U.S. Pat. No. 3,392,019 issued July 9, 1968. If desired, the photographic elements of this invention can be processed in hardening developers such as those described in Allen et a1. U.S. Pat. No. 3,232,761 issued Feb. 1, 1966; and in roller transport processors such as those described in Russell et al. U.S. Pat. No. 3,025,779 issued Mar. 20, 1962; or by surface application processa ing as described in Example 3 of Kitze U.S. Pat. No. 3,418,132 issued Dec. 24, 1968.

The silver halide emulsions used with this invention can be used to prepare photographic elements designed for developing out processing, or print out exposure as described in Fallesen U.S. Pat. No. 2,369,449 issued Feb. 13, 1945; or for photodevelopment as described in Hunt U.S. Pat. No. 3,033,678 issued May 8, 1962, McBride U.S. Pat. No. 3,287,137 issued Nov. 22, 1966, and Colt U.S. Pat. NO. 3,418,122 issued Dec. 24, 1968.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

We claim:

1. A method for adjusting the triboelectric charging characteristics of materials subject to the generation of an electrical charge when a surface thereof is brought into contact with another usually dissimilar surface comprising the steps of:

a. measuring the electrical charge generated when the surface of the material normally subject to charging is brought into contact with said usually dissimilar surface under controlled conditions;

b. measuring the electrical charge generated when surfaces of charge control agents are brought into contact with said usually dissimilar material under controlled conditions;

0. based on the results of step (b), selecting at least one charge control agent which is capable of providing the adjustment desired for controlling the charging characteristics of said material; and

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Classifications
U.S. Classification430/528, 430/115, 430/533, 361/225, 428/922, 430/539, 430/108.2, 430/531, 252/500, 361/212, 430/529, 430/108.14, 430/108.4, 430/526
International ClassificationG03C1/85, C08J7/06
Cooperative ClassificationC08J7/065, Y10S428/922, G03C1/85
European ClassificationC08J7/06B, G03C1/85