US 3138533 A
Description (OCR text may contain errors)
United States Patent 3,138,533 SANITARY TISSUES Leo J. Heim and Raymond J. Norton, both of 805 11th St. NW., Washington, D.C. N0 Drawing. Filed May 27, 1958, Ser. No. 738,010 5 Claims. (Cl. 167-434) This invention relates to improved sanitary tissue, more particularly to facial and sanitary tissue products which possess antibacterial and deodorant properties.
As is known there is a constantly increasing use of facial tissue products. These products are fabricated of soft highly absorbtive fibers formed into a relatively thin matted sheet on typical paper making machines such as a cylinder machine or a modified Fourdrinier. These disposable tissue products are used for many purposes in personal toilet, such, for example, as a disposable handkerchief and as a cleaning sheet for Wiping and cleaning topical surfaces to remove perspiration and dirt. In all such uses it would be particularly beneficial and advantageous to employ a tissue product which is inherently antibacterial and which preferably also possesses superior cleaning or detergent properties. When the presently employed tissues are used for example in lieu of a handkerchief to pick up or receive nasal discharges in effect they become an immediate and dangerous repository for the many bacteria, including pathogenic microorganisms, emanating from the upper respiratory tract. If such contaminated tissue is not quickly flushed away in toilets but are indiscriminately discarded in open receptacles such as waste baskets, on public vehicles and thoroughfares, or, as is often the case, are carried in a purse or in the clothing of the user they constitute a very real health hazard. Many of these organisms are of marked viability and hence this hazard may persist for a very considerable period of time. This same situation obtains, albeit to a lesser degree when such tissues are used to wipe off or absorb body perspiration because of the pick up of bacteria present on the skin.
A major objective of this invention is to obviate this hazardous condition by providing a tissue of the type described which is inherently bacteriostatic and germicidal under all conditions of use.
As noted a major use to which such tissues, in their various forms, are put is as a cleaning tissue to wipe ofi perspiration and dirt from the face and other topical areas. In many cases the user may wet the tissue sheet to improve such cleaning action. Such tissues are also used to Wipe the face areas prior to the application of face lotions or powders. In such a use major desiderata are not only to clean the topical areas to which the tissue is applied but also, to as great a degree as possible, aseptically cleanse such areas and render them bacteriostatic for as long a period as possible.
Another paramount objective of the invention is to achieve such desirable results by incorporating in the tissue compounds which have highly effective detergent action for the removal of dirt and skin exudates and which in use act to apply a film of antibacterial agent on the contacted area which on drying persists for a long period and is effective in situ as subcutaneous bacteria is exuded to the skin surfaces.
It will be appreciated that what has been said of the desirability of employing a facial tissue as a carrier vehicle for germicidally effective agents applies generally to sanitary tissues. Manifestly such a sanitary tissue which has marked germicidal activity and effect against fecal organisms and which imparts a residual bacteriostatic and bactericidal film in the axilla area is most desirable.
Improved tissues possessing the desirable characteristics set forth and functioning in the novel manner de- "ice scribed are comprehended within the concept of the present invention. In addition, as will be elucidated hereinafter the invention also contemplates the production of such tissues which possess marked potential deodorant properties which renders them particularly valuable and desirable for personal hygiene i.e. for deodorization of under arm and other axilla areas.
Facial and sanitary tissues having the described improved characteristics may readily be produced by saturating the formed web of tissue at any suitable stage in its production with a specifically formulated solution which imparts the novel properties to the tissue. Such saturation or impregnation may be done at any suitable stage prior to final drying. During the drying step, as for example on the drying cylinders, the water in the sheet and that applied by way of the germicidal solution is evaporated and the several (non-volatile) components of the solution are distributed in and on the fibers of the sheet. The enumerated characteristics may be imparted to the tissue by utilizing predetermined concentrations of selected cationic quaternary amines of exceptionally high germicidal activity and bacteriostatic potency. These germicidal agents are preferably employed with carefully correlated amounts of certain selected water soluble compounds which enhance the Wetting action of the surface active quaternaries, improve its solubility and rapid dispersion in water and which synergizes or potentiates the germicidal and deodorizing action. The compounds employed are all water soluble, and are non-volatile and stable under the conditions of drying of the sheet and thus appear in even distribution in and on the fibers of the final dried tissues. The components employed also improve the softness of the sheet and impart a desirable soft tactile reaction or emolliency to the tissue.
In the preferred method of producing the novel tissues the germicidal quaternaries are employed with certain compatible wetting agents such as selected nonionic or cationic wetting agents which increase and/or improve the wettability of the solutions derived from the treated tissues together with selected compounds which improve the solubility of the quaternary compounds and preferably also with effective chelating agents which function to synergize or enhance the germicidal action.
The cationic quaternary amines employed herein are positively charged and hence are fixed by or substantive to the negatively charged cellulosic fibers. It will be understood that the concentration of the quaternary compounds in the treating or impregnating solution is chosen and adjusted such that a sufiicient excess of the quaternary compounds are present above that required for absorption or fixation by the negatively charged fibers, to insure that on final drying of the saturated paper a calculated predetermined amount is present in and on the fibers as a residual film or adhered coating. Cellulose fibers will absorb or fix an amount of the quaternary compound equivalent to about 0.5% by weight of the dry weight of the tissue.
In use when such treated tissue is wetted, as by contact with moisture on the skin or by wetting with water, such compounds pass into solution and are dispersed in the contacting aqueous medium. The adjuvants employed with the quaternary amines present the unique advantage of having a high wettability on skin tissue and excellent detergency and also an excellent wettability 'for keratinaceous substances such as human hair. The solutions derived by wetting of the treated tissue thus readily Wet the skin and hair and facilitate the transfer of the germicidal agent into the pores of the skin and into the follicular areas to insure active bactericidal and deodorizing action on the skin areas. The several adjuvants as noted are freely water soluble, thermally stable under drying temperatures and are non volatile under the con ditions of tissue production. These germicidal compounds are non-irritating in the use dilutions and have no deleterious action on clothing. In fact when absorbed in clothing they persist and are retained even after numerous launderings and exert their bacteriostatic and deodorizing action in the clothes. As will be seen more fully hereinafter the concentration of the impregnating solutions may be chosen and controlled to impart to the tissue not only marked antibacterial properties but also, in higher concentrations of the quaternary amine, to confer deodorizing action on the solutions diffused or otherwise produced from the treated tissue.
The cationic quaternary amines of choice comprise a group which are thermally stable, non-volatile, colorless, odorless and non-irritating and which are characterized by marked germicidal and deodorizing activity. Typical preferred, although not exclusive members of this group include: diisobutyl phenoxy ethoxy diethyl dimethyl benzyl ammonium chloride (Hyamine 1622), methyldodecylbenzyl trimethyl ammonium chloride (Hyamine 2389), diisobutyl cresoxy ethoxy ethyl dimethyl benzyl ammonium chloride (Hyamine 10-X), and octyl phenoxy ethoxy ethyl dimethyl p-chlorobenzyl ammonium chloride (Hyamine 2744). These several compounds readily form water soluble systems and even in very low concentrations have a high germicidal activity and rapid killing power. Such solutions display phenol coefficients of from 200 to 400 or more at dilutions of from 110,000 to 1:50,000 against a wide variety of organisms. These compounds are effective wetting agents per se and in concentrations of the order of 0.1% reduce the surface tension of water down to 32 degrees per sq. cm.
The preferred compatible wetting agents employed comprise one or more water soluble non-ionics of the alkylaryl polyether alcohol type such as the octyl phenoxyethanol group. A most suitable member of this group is Triton X-100 (produced by Rohm & Haas Co.).
As noted the preferred treating solutions (and the resulting treated tissues) preferably are made to contain predetermined amounts of an effective chelating agent which chelates the polyvalent ions in the solution. The use of the chelating agent eliminates any typical calcium and magnesium hardness in the water used in the make up of the solution. Also and most importantly an effective chelating agent chelates or binds up the polyvalent trace metals which are involved and required in the metabolism of microorganisms and thus accelerate and enhance the essential germicidal action of the germicidal agents by rendering such organisms less resistant to such agents. Preferred agents of this type comprise the sodium salts of ethylene diamine tetra acetic acid. These compounds impart alkalinity to the solutions in which they are dissolved; such alkalinity increases the germicidal effectiveness of the germicidal agents employed. Obviously the alkalinity should be controlled within a narrow range so as to avoid irritation to the normal acid skin. The solutions may be adjusted to close to neutrality i.e. between about pH 6.5 to 7.5 as for example by using a suitable organic acid such as citric or tartaric acid. It will be understood that if desired the water hardness may be reduced by employing suitable inorganic sequestering agents such as sodium hexamethaphosphate to sequester the calcium and magnesium ions. The chelating agent is employed in relatively small amounts i.e. in slight excess of the stoichiometrical quantity to chelate the described trace metals.
As intimated previously it has been found that the effectiveness of paper tissues for disinfection and deodorizing purposes is markedly increased by including in the treating solution (and hence in the final dried tissue) a cosmetically acceptable water-soluble compound which enhances the solubility of the essential germicidal compounds and accelerates their diffusion into the surrounding aqueous medium or wetting of the tissue. It has been found and established by tests that urea functions very effectively for this purpose. This is readily dissolved in the treating solution and on drying is incorporated in the final tissue. The action of urea in the system is most beneficial although the mechanism of its role is somewhat obscure. When a tissue of the character described is wetted either by contact with moist skin or by preliminary wetting with water preparatory to rubbing, laving or sponging the skin, the urea in conjunction with the other components of the impregnating solution serves to increase the solubility and/or diffusibility of the quaternary insuring a more rapid elution or dispersion of the germicidal agent and associated wetting agents from the fibers of the tissue into the ambient aqueous medium and insures a more rapid transfer of the essential germicidal agent to the skin surface contacted by the wetter tissue. Whether this is a peptizing or electrophoretic phenomenon is not known; whatever he the physico chemical factors involved such improved action is clearly demonstrable. As indicated the dispersion of urea throughout the tissue modifies the tactile effect imparting a desirable smoothness: furthermore to a definitely perceptible degree the application of the urea containing germicidal confers residual emolliency to the skin.
It is to be observed at this point that the cationic quaternary amines employed are highly effective for bactericidal and bacteriostatic action in reasonably low concentrations i.e. of the order of 200-400 p.p.m. When deodorization is desired the concentration should be increased. Efiective deodorization of body odors and of extraneously applied odors such as onion, garlic and similar odors on the hands can be achieved by contacting the odoriferous sites, such as under-arm areas, face and hands, the feet etc. with active solutions of the character described of a concentration of the order of 1000 p.p.m. or more. It is to be noted that cationic quaternary amines described can be employed on the skin in concentrations of 2.0% without danger of skin irritation. Thus it is apparent that the novel tissues of the invention can be made to carry amounts which are most effective for the deodorizing function but which are greatly below the threshold of possibile or potential dermatological irritation. When it is considered that in the use of the tissues the wetting material or solvent (i.e. water and/or body exudates) is only that quantity which is picked up by contact with the skin on the one hand, or the small amount of water necessary to wet and saturate the dry tissue on the other it is apparent that the actual quantitative amount of the quaternary and its correlative functioning compounds in and on a sheet of tissue need only be quite small. This, as noted, can be varied within the range necessary to accomplish the germicidal bacteriostatic and deodorant functions. It goes without saying of course that a tissue carrying a concentration of the quaternary compounds adequate for deodorization is ipso facto effective for the antibacterial action. It is particularly to be observed at this point that the described quaternary amines function as true chemical deodorants and not as antiodors (since they themselves are odorless) or as astringent or so called anti-perspirant agent since they have no astringent effect or action on the epidermis. On the contrary as previously pointed out the solutions derived from the treated tissues have high penetrability into the pores and hair follicles of the epidermis and thus are made clfective in the deep recess of the skin or at the very site of subdermal bacteria exudation.
The efficiency of the invention can more readily be appreciated and evaluated from a consideration of tests conducted with the novel tissues produced according to the invention.
A solution (Solution A) was prepared which contained about 2000 p.p.m. of Hyamine 2389 and 600 p.p.m. of Triton X-l00. A similar solution (Solution B) was also prepared which contained about 2000 p.p.m. of
Hyamine 2389, 600 p.p.m. of Triton X-100 and a quantity of urea equivalent in weight to the weight of the Triton. Twelve sheets of a facial tissue (Scotties) were saturated with Solution A and twelve with Solution B. The unabsorbed portions of Solutions A and B were tested with indicator paper and displayed a substantial concentration of the Hyamine i.e. about 500 ppm, showing that the tissues had absorbed substantial amounts of the germicidal agent in the fibers and retained a concentrated film of solution on and in the tissue which on subsequent drying left a coating and/ or film of the active ingredients of the solution on the paper surfaces.
The bacterial action of the agents contained in and on the dried tissue was then tested in vitro by the agar cup plate and tube methods. Test squares (17 mm.) were cut from the tissues treated with Solutions A and B and similar squares were cut from the untreated or control tissue. Petri dishes of nutrient agar were surface inoculated with various stains of representative bacteria and squares of each of the treated and untreated tissue were placed on these inoculated plates. After twenty-four hours incubation the plates were examined for zones of inhibition indicating anti-bacterial action. The results are indicated in Table I below. In this table Sample A is the tissue specimen treated with Solution A, Sample B the one treated with Solution B and Sample C is the commercial untreated tissue.
1 Inhibition to different degrees depending on organisms present.
The results recorded in Table I clearly demonstrate the marked antibacterial action characteristic of the treated tissues. The test also clearly illustrates the striking unexpected improvement in antibacterial action against some bacteria which is derived from the use of urea in the novel tissue product. The anti-bacterial action of the components of the tissue against Proteus vulgaris is also notable for this bacteria, 'as is known, is a very resistant type.
To further illustrate the antibacterial efiiciency of the novel tissues of the invention culture tube tests were conducted. In such tests strips of 25 x 200 mm. of each specimen i.e. Sample A; Sample B and the control or untreated tissue, Sample C, were placed in culture tubes containing ml. of nutrient broth enriched with rabbit blood. One set of tubes was then inoculated with Staphylococcus uureus and another with Proteus vulgaris and were examined for growth after five days incubation at 37 C. The results of such tests are indicated in Table II Table II [Results after 5 days incubation] Organism Sample A Sample B Sample 0 Staphylococcus aureus Negative Negative. Heavy Growth. Proteus oulgaris o do Do.
terial, bacteriostatic and deodorizing action. This can be seen froma consideration of tests conducted with treated sheets. Tissue sheets which were saturated with Solution B and then dried were used in the tests. One such sheet was immersed in 60 ml. of water in a glass container and slightly agitated for a period of about a half minute. A portion of the solution was decanted off onto the skin of the test subject and spread over the skin as a thin film. The aqueous film was tested with indicator paper and displayed a concentration of about 500 p.p.m. of the cationic quaternary germicidal agent. This as will be appreciated is greatly in excess of the amounts (approximately 200 p.p.m.) necessary for a rapid germicidal kill.
Another test which directly simulates the actual conditions of use was conducted. A sheet of tissue carrying the components of Solution B was wetted thoroughly with tap water and rubbed several times over the upper surface of the hand of a test subject. The film of solution was allowed to air dry. The subject proceeded with normal activities including, among other things, drawing on and withdrawing gloves. After a period of about four hours the treated epidermal area was wetted with about 15 ml. of water and the film of solution formed by the applied water was tested with indicator paper. Such test established that the solution had a concentration of over 400 p.p.m. of the Hyamine and hence was of high antibacterial activity. The retention and persistence of the film or coating of the active agents attests the excellent wetting power of solutions derived from the treated tissue and establishes the fact that such residual deposits or film insure pro longed antibacterial protection.
Other tests were conducted to determine the deodorizing action of the treated tissues. For example, drops of concentrated onion and garlic juice were deposited on the upper part of the hands of test subjects and rubbed over the surface to provide a film which was allowed to air dry. One hand was patted with a wetted tissue impregnated with Solution A and the other hand was left untouched. On air drying of the solution applied from the tissue it was found that no odor was perceptible whereas the other (control) unwetted hand had a pungent odor of the onion or garlic. Similar tests with tissues corresponding to Sample B showed the same results. Numerous tests of underarm areas likewise established the marked deodorizing action produced by laving, rubbing or swabbing these areas with the wetted tissues described above.
As will be appreciated the actual quantity of the active agents particularly the active germicidal agent in and on a given sheet of tissue can readily be established and controlled by the concentration of these compounds in the treating solution.
Itwill be understood that the specific examples of the treating solutions given above are illustrative of the type of solutions employed for impregnation. Since the components of the solution are freely water soluble any desired concentration range of each ingredient may be employed. The anionic wetting agent may be used in relatively greater or less proportions than those set forth in the examples, as a general rule it is preferred to employ this in an amount equivalent to about one third, more or less, of the cationic quaternary amine. The amount of the urea used in the solution is not critical and may if desired be used in considerably greater proportions that are set forth in the examples particularly when marked emolliency of the residual film on the skin is desired. Because of its very effective peptizing action urea insures a more effective cleansing action because of the improved wipe off effect of dirt which it imparts to the tissues. The quantity of the chelating agent which is employed, as noted previously, need only be slightly in excess of the amount necessary to chelate the trace metals and calcium and magnesium if such are present i.e. if not already sequestered.
If desired other beneficially acting adjuvants may be employed to confer additional advantages on the tissue.
Thus, for example, if desired an amount of a wetting agent having oil and some Water solubility such as Triton-45 may be included in the formulation of the tissue impregnating solution. This may be added in an amount up to its solubility in the quantity of water required to thoroughly wet or saturate the treated tissue. This agent functions to confer some oil solubility to the tissue and thus facilitates the removal of oily deposits on the skin.
In some circumstances as where a more smooth or emollient feel of the tissue is desired non-toxic, nonirritating compatible humectants such as selected glycols e.g. ethylene glycol may be included in the impregnating bath in the desired small amounts. It will be appreciated that the invention presents a broad range of utility in the field of personal sanitization and deodorization. The principles of the invention may be utilized to produce a variety of improved products. Important among these is the production of novel disposable cellulosic insoles for shoes. In this particular use it is to be observed that the impregnated insole when wetted with perspiration from the feet functions most elfectively as a foot and shoe deodorant. Also and very importantly such impregnated paper can be made to contain sufiicient of the described cationic quaternary amines to inhibit the growth of Athletes Foot microorganisms. Such inhibition is secured with I-Iyamine solutions of a strength of about 1:700. Since the actual quantity of aqueous exudate from the feet is relatively small it is apparent that, but relatively small amounts of the Hyamines need be employed in such insole materials. Tissues produced according to the invention may be most advantageously employed in under-arm pads for deodorization and protection of clothing. These tissues may be folded and used as replaceable and disposable refills for open mesh .pad units. The absorption characteristics of the tissue coupled with the marked germicidal and deodorant action establishes such tissues as ideal for this use.
As pointed out previously the presence of urea in the treated tissue in association with the quaternary amine increases the solubility of the quaternary when it is dissolved by application of water or by absorption of perspiration, a similar improved solubility is effected by employing other solubilizing agents such as sodium citrate or sodium lactate. The use of urea is preferred because in its correlated association with the quaternary compounds and the other compatible adjuvants, such as the nonionic Wetting agents and chelating compounds, it performs functions of profound significance in insuring the full or optimum advantages in the use the improved tissues of the invention. The presence of urea imparts characteristically novel and eminently beneficial properties to the end product, i.e., the impregnated toilet, facial or bath towel tissue. As explained previously, in an aqueous solution system containing a quaternary amine urea confers improved solubility on the amine. This is probably due to the fact that such quaternary compounds are not ionic solutes in the accepted strict sense but rather are colloidal solutes which the urea acts to disperse probably because of its peptizing action. It is rather generally accepted that such quaternary compounds having a large or ponderable cation or positive portion of the molecule are rather weakly ionized and that their activity and solution behavior, to a considerable degree, involve electrophoretic phenomena. lated, and then has been considerable experimental evidence adduced to prove such postulate, that the substantive attraction of the positively charged quaternary to the negatively charged cotton and wool fibers involves a monomolecular layer or film of the quaternary which is together adherent (substantively) to the fiber by reason of the electrical extraction and the remainder of the quaternary colloid in which is less tenaciously attracted to the monomolecular layer of the quaternary. It would appear that in the environment of the present invention It has been postuthis quantum of the more weakly adherent quaternary is peptized and dispersed by the urea insuring its more rapid and complete diffusion in the wetting water and its consequent availability at the area of contact use, i.e., on the skin or other surfaces to which the wetted tissue is applied. Whatever may be the rationale or mechanism of solution or dispersion involved it is a fact, as previously explained, that the incorporation of urea in the tissue in homogeneous distribution vis-a-vis the quaternary insures a more rapid and complete elutriation of the active quaternary from the tissue for transfer in the aqueous carrier to the skin or other site to which the tissue is applied. When the novel impregnated tissues are used for cleansing the skin the inherent detergent action of the quaternary compounds is enhanced by the presence of urea probably by reason of a type of peptizing action.
The urea, as intimated, performs other very valuable functions in the tissue in its association with the active antibacterial agents. As previously noted the pH of solutions applied to the skin should be controlled within rather close limits; since the skin is normally of acid pH any undue alkalinity in topically applied solutions tend to cause irritation. In the novel tissue of the invention urea, among other things, acts most elfectively as a buffering agent. This is most useful in the present invention because of the fact, previously noted, that while the quaternaries employed are stable over a wide pH range their germicidal activity is greater in alkaline solutions. The buffering action of urea is thus of marked utility in maintaining optimum conditions for antibacterial action.
The addition of urea to the tissue in association with effective germicidal agents confers further unique and particularly valuable properties to the tissue product. The solutions derived from the new tissues when applied to the skin not only inactivates such bacteria as may be present but also, due to the proliferating action of urea, accelerates healing of skin wounds. Thus the novel tissue presents an economical, very effective and convenient bandage for wounds such as razor or knife cuts, skin abrasions and the like. Since the tissue is intrinsically germicidal it can be applied directly to a wound, preferably after it is dampened or wetted with water.
The facial tissues described herein are particularly efiicacious as cosmetic cleaning tissues, as, for example, for the removal of facial creams from the skin. In such case the nonionic wetting agent and the quaternary amine compounds, by reason of their excellent detergent and emulsifying action, accelerates the removal of the oleaginous creams.
As noted previously when the novel tissue product is wetted and is rubbed over or patted on the skin a film of the germicidal solution is formed on the skin area. When such film is allowed to air dry an invisible, imperceptible bacteriostatic film of the active agents adheres to the skin. This provides prolonged germicidal protection and also serves as an excellent preparation or base on which to apply face powders. The electrophoretic 'nature of the quaternary amine appears to play a role by more firmly retaining the powder on the skin.
The treating solutions, as previously indicated, may be readily applied to the cellulosic tissue at any convenient stage in the course of its fabrication. One method, as noted, is to apply the treating solution of selected concentration to the formed sheet by spraying on the sheet prior to final drying. In such a procedure some of the treating solution is taken up in the dryer felt and ultimately passes into the white water. When applied in this manner the operation of the saveall, if the floatation type, should be adjusted to adapt it to the recovery of the positively charged fibers.
Another simple and recommended procedure is to apply a concentrated solution of the treating agent to the paper web, and preferably to the underside thereof, after it passes over the final dryer and before it is taken up on the creping roll. In 'such an operation the concentrated solution may be fed under gravity head or siphoned from a feed pipe or manifold into a series of nozzles spaced from and extending laterally across the web and sprayed on the sheet in atomized form by compressed air or steam forced through the nozzles. In a typical operation of this type the nozzles may be spaced about fifteen inches more or less from the paper web and are of the flat spray type designed to deliver a flat spray pattern of from about eight to eleven inches wide, more or less, from each nozzle. The nozzles are spaced across the web at such predetermined intervals as will insure a continuous spray pattern across the web and thus uniformly distribute the atomized solution over its surface. Such nozzles for example may be operated with an air pressure of from about to 30 psi. to deliver from .15 to about .35 gallon per nozzle per hour depending on the gravity head or siphon height. The fiat atomized spray from the nozzles are directed at a selected angle to the plan of the web to secure maximum absorption of the liquid droplets in the paper web; such nozzle directional angle should be correlated with the vertical displacement of the nozzles from the plane of the web and may vary for example between about to 45 more or less.
In paper tissue machines of the type described the web passes over the dryer, such as a yankee drier, at a high speed of the order of 1200 ft. per min. As it leaves the dryer in passage to the creping roll the formed paper sheets are dry and in a heated condition. This dry condition of the paper coupled with its substantial sensible heat and inherent absorptiveness of the paper fibers insures a rapid pick up and absorption of the finely atomized concentrate. In this method of applying the aqueous concentrate the high velocity web of paper in effect forms a confining blanket against which the atomized liquid impinges and in which it is absorbed. Due to its high velocity the moving web induces a concurrent flow of a skin or stratum of air which entrains and carries the dispersed liquid droplets into contact with the paper web. This insures, so to speak, a more prolonged period of contact of the spray with the surface of the paper sheet and insures maximum absorption of the atomized liquid.
In this type of operation, depending essentially on the efficiency of the nozzles and the accuracy of their spray pattern some loss of liquid will occur due to the passage of some of the sprayed liquid over or beyond the edges of the web. This atomized material passing into the air above the sheet will tend to be drawn into the existing ventilator hood over the yankee dryer. If desired to insure a more rapid induction of this unabsorbed spray the lip of the ventilator hood over the dryer may be extended over the area of the web to which the spray is applied. Alternatively a separate ventilating hood may be positioned conveniently over the spray escape area and the withdrawn material cooled to condense and recover the dispersed liquid which may be reemployed in make up of the concentrate.
With this type of operation using concentrated solutions of the active agents for application to the dried tissue it will be understood that the amount of water used in the treating solution should be carefully controlled to avoid undue wetting of the sheet. In the usual circumstances the quantity of water in the concentrate should not exceed about 2% by weight of the paper i.e. 40 lbs. per ton of paper treated. Since the chemical components of the treating solution are all readily water soluble low viscosity solutions of high concentration of the solutes may be used. Whenever found desirable the treating solutions may be preheated to increase its fluidity.
It is to be observed that while the quaternary amine compounds employed herein are not corrosive per se concentrated aqueous solutions tend to accelerate the corrosion of iron, steel and imperfectly galvanized iron; this tendency to rusting can be decreased by adding to the 10 concentrate a compatible inhibitor such as triethanol amine phosphate or sodium nitrite in effective amounts of the order of about 0.5% of the concentrated solution.
The concentrated treating solutions employed are of low surface tension and hence tend to foam under agitation. Foaming tendency can be materially reduced by incorporating a cosmetically acceptable defoamer in the treating solution. It has been found that a silicone defoamer, specifically Dow Corning anti'foam B or Dow Corning A Femulsi, are very effective for this purpose. These may be used in small concentrations of from 0.000l% to 0.02%. The silicone not only does not detract from the character and properties of the final tissue but appears to improve its feel or emolliency and is tasteless, non-toxic and non-allergenic.
It is apparent that the concentration of the treating solution for the impregnation of the tissue with the desired quantities of the active agents can readily be calculated. This is the quantity necessary to satisfy the substantive demand of the cellulose plus the excess deposit or film of ingredients in and on the cellulosic fibers which is required to insure the desired use concentration when the tissue is wetted with aqueous media such as perspiration or added water. As noted previously effective antibacterial action is obtained in concentrations of -200 ppm. of the germicidal agent in aqueous solution. For deodorization and inhibitions of growth of Athletes 'Foot organism higher concentrations of the order of 1000 ppm. are recommended.
In a typical operation for producing a tissue change effective available amormts of the active germicidal agent the Web of paper tissue passing from the final dryer to the creping roll is sprayed with a concentrated aqueous solution containing for example 5 lbs. of Hyarnine 2389, 1.5 lbs. of urea, 1 lb. of Triton X-100, about 2 cc. of Antifoam B and about 5 oz. of Versene 9" dissolved in 4.5 gallons of Water. This solution is sprayed on a ton of the paper tissue passing from the dryer to the creping roll in the course of an hours run. In usual circumstances the web is severed after about one half hour of operation, the take up roll, containing the dried tissue is removed and replaced with a new take up roll after which operation is continued. During this change over period while the broke is accumulating the spraying system is cut off by operation of suitably positioned valves in the air and liquid lines.
Such a treated tissue contains up to about 3% by weight of the germicidal agent and on being wetted with water displays a germicidal agent concentration of 300- 400 p.p.m.
It will be understood that while for illustrative purposes certain germicidal quaternary compounds have been described the invention contemplates the use of any germicidal cationic quaternary compound, or mixture thereof, which function similarly to those described. Thus among the active germicidal agents which may be employed are alkyl (C12-Cl6) dimethyl benzyl ammonium chloride, cetyl trimethyl ammonium bromide, lauryl pyridinium chloride, cetyl pyridinium chloride N (acyl colamino formyl methyl) pyridinium chloride and the like.
While preferred embodiments of the invention have been described and several beneficial uses of the novel cellulosic tissue have been discussed it is to be understood that these are given to illustrate the principles of the invention and not as limiting it except as such limitations are clearly imposed by the appended claims.
1. An absorbent sanitary and facial tissue characterized by inherent antimicrobial and emollient action on application of the tissue to moistened topical areas which comprises a hydrophylic, absorptive, porous sheet of negatively charged cellulose fibers in and through which is homogeneously incorporated a germicidally effective amount of a cationic quaternary amine and an amount of urea suflicient to substantially reduce the substantivity of the cationic amine to the cellulose fibers, the quantity of the amine being suflicient to give a concentration of from 150 to 2,000 parts per million in water sufiicient to saturate the tissue and the quantity of urea being at least one-third the quantity of the amine.
2. An absorbent tissue product according to claim 1 in which the said amine is chosen from the group consisting of; di-isobutyl phenoxy ethyl dimethyl benzyl ammonium chloride, monohydrate, di-isolutyl cresoxy ethoxy ethyl dimethyl benzyl ammonium chloride, and mixtures of alkyl tolyl methyl trimethyl ammonium chlorides with alkyl groups from C H to C H 3. An absorbent tissue according to claim 1 in the fibers of which is incorporated a quantity of a non-ionic wetting agent of high detersive activity and in an amount equivalent to at least one-third the quantity of the amine.
4. An absorptive tissue according to claim 3 in which the non-ionic wetting agent is an alkyl aryl polyethylene alcohol.
5. A process of producing a facial and sanitary tissue which comprises forming a web of matted, purified cellulose fibers, saturating the web with an aqueous solution consisting of at least 2,000 parts per million of a cationic quaternary amine, at least 600 parts per million of a nonionic wetting agent of high detersive activity and at least 300 parts per million of urea and then drying the saturated sheet.
References Cited in the file of this patent UNITED STATES PATENTS 2,474,412 Bersworth June 28, 1949 2,524,219 Bersworth Oct. 3, 1950 2,544,732 Shechnmeister Mar. 13, 1951 2,689,814 Nicholls Sept. 21, 1954 2,709,665 Campbell May 31, 1955 2,756,647 Thompson July 31, 1956 2,833,669 Ziegler May 6, 1958 2,837,462 Morin June 3, 1958 FOREIGN PATENTS 290,364 Great Britain May 14, 1928 500,815 Canada Mar. 16, 1954 OTHER REFERENCES U.S. Dispensatory, 25th ed., Part I, pages 1475-1477.