US 3736259 A
A fast-foaming, carpet cleaner containing water-soluble surfactant, silica, higher aliphatic alcohol, water and liquefied propellant. The composition which is dispensed from an aerosol container provides improved cleaning, exceptionally stable foam which prevents oversetting of the carpet and resoiling retardation.
Description (OCR text may contain errors)
United States Patent 3,736,259 CLEANING COMPOSITIONS AND METHOD Charles Edward Buck, Caldwell, and Victor Earl Shealfer, Glen Gardner, N .J., assignors to Colgate-Palmolive Company, New York, N.Y.
No Drawing. Continuation-impart of application Ser. No. 20,398, Mar. 17, 1970. This application July 9, 1971, Ser. No. 161,276
Int. Cl. Clld 7/50 U.S. Cl. 252-89 '8 Claims ABSTRACT OF THE DISCLOSURE A cleaning composition for shampooing carpets including water, a detergent and an aliphatic C -C fatty alcohol, finely divided silica, and a water-soluble alkali metal phosphate or borax or a mixture thereof for retarding the formation of sediment.
This application is a continuation-in-part of copending application Ser. No. 20,398 filed Mar. 17, 1970.
This invention relates to a composition for cleaning carpets and more particularly to an aerosol foam carpet cleaner.
Carpets are commonplace in the household. They are made in numerous sizes, shapes, and fabrics. Most households have at least one of the many types available. Since vacuuming of the carpet only removes loose dirt, a more effective means is required to remove soil which is strongly attached to the carpet fibers. Although professional cleaning is quite effective in removing embedded dirt and soil, it has its disadvantages, the most evident being cost. Equally burdensome is the necessity of removing the carpet and transporting it to the cleaning plant. This not only creates problems in removing and transporting the carpet, but it also leaves the floors uncovered for a long period of time giving a less attractive appearance to the home.
In view of both the economical and physical inconveniences, the need for a do-it-yourself carpet cleaning composition arose. In response to this need, many cleaning compositions were developed and commercially exploited. They were formulated in a variety of forms, i.e., dry powder, liquid, and aerosol. Although these compositions have saved consumers large expenditures on professional rug cleaning, many compositions require special equipment necessitating further expenditure of funds and equipment storage problems. Other problems resulting from the use of do-it-yourself compositions are the slow drying of the carpets after they have been shampooed, and the leaving of tacky, sticky residues which promote resoiling of the carpet. The slow drying of the carpet is the result of water, used in shampooing, permeating the backing of the carpet. Since the backing of the carpet is not exposed to the air, the soaked in water takes a long time to evaporate. Resoiling is also a major problem and although compositions are marketed containing detergents which do not leave a sticky or tacky residue, resoiling is not retarded and it is necessary then to clean the carpet more often.
The present invention resides in the provision of cleaning compositions for carpets wherein the foregoing and related disadvantages are eliminated or at least mitigated to a substantial extent, and more particularly to such compositions whose ingredients do not coagulate to form a hard, gelatinous precipitate or sediment.
The present invention is more particularly directed to a fast-foam forming aerosol cleaning composition for carpets which provides improved cleaning, retardation of the rate of resoiling, prevention of excessive wetting and promotion of faster water evaporation and more specifically to such aerosal compositions whose ingredients, espe- 3,736,259 Patented May 29, 1973 cially soil retardants and detergents do not coagulate forming hard, gelatinous precipitate or sediment.
It was observed that upon aging of containers containing cleaning compositions comprising water-soluble surfactant, higher aliphatic fatty alcohol, silica and water, a hard, gelatinous sediment or precipitate is found on the bottom of the container.
A hard, gelatinous sediment was also found in aged aerosol containers containing the above composition and a propellant. The hard, gelatinous precipitate forms in less than six Weeks of shelf aging and sticks to the bottom of the container. It is not loosened upon shaking. As a result, the material forming part of this sediment especially the Soil retardant, i.e. silica, and the surfactants are not available for full delivery to the consumer for use in cleaning. In aerosol formulations the gelatinous sediment is more of a hinderance since not only is the soil retardant and surfactants forming this sediment not available for cleaning, but any of this sediment which does become loose as a result of the pressure in the aerosol can is not sprayable and becomes lodged in the spray buttons preventing complete product exhaustion, causing button clogging and altering of the spray pattern.
It was discovered that when a phosphate or borax or mixtures thereof is added to the above compositions these co'mpositions do not form hard, gelatinous sediments on aging in the container. If any precipitation does occur in the phosphate or borax containing cleaning compositions, the precipitate is a flocculent one and does not stick to the bottom. It is easily suspended on shaking and therefore the contents of the container are fully deliverable for use by the consumer. Any precipitate which develops in aerosol cleaning composition containing phosphates or borax is sprayable and does not clog the spray button or alter the spray pattern.
Although non-aerosol cleaning compositions come within the scope of the present invention, the best mode contemplated by the inventors for carrying out their invention is aerosol cleaning compositions since these are more economical and convenient to use.
The aforestated aerosol composition is composed primarily of water-soluble surfactant, higher aliphatic, fatty alcohol, silica, phosphate, or borax or mixtures thereof, water, and propellant. The inventive compositions are formulated by first preparing a concentrate which essentially contains surfactant, silica, long chain alcohol, agent for retarding hard gel formation and water. The concentrate is then placed into a suitable aerosol container to which liquified propellant is added in the conventional manner. This novel formulation prevents over- Wetting of the backing of the carpet because of the amazing, unique stable foam which is formed. The foam lattice holds back most of the water molecules from reaching the backing of the carpet thereby preventing saturation and concomitant shrinking of the carpet.
Although silica is a major contributor to hard, gel formation, the beneficial effects it imparts to cleaning compositions far outweigh the hindering effects of its gel forming nature. Silica provides superior foam stability and anti-wetting properties. Foams not containing silica are wetter and therefore are not as effective as silica containing foams in preventing water from draining into and permeating the carpets backing. The compositions of the present invention provide a drier foam mainly due to the fine dispersion of silica throughout the foam lattice. The dispersed silica augments the retaining ability of the foam achieving more eflicient retention of the water molecules within foam structure. The silica also provides a greater surface area from which water may more readily evaporate with concomitant acceleration of the drying time of the carpet.
Commensurate with the anti-wetting properties of silica are its resoiling retardation properties. It is postulated in explanation thereof that the silica particles tend to embed themselves and fill the void and interstices present in the fibrous material comprising the carpet, in effect blocking those sites which would otherwise serve as reservoirs for soil, dust, grease and the like. As will be readily evident, the useful life of the fabric, in view of the protective action of the silica particles, can be significantly enhanced. Moreover, actual carpet cleaning is greatly facilitated in view of the substantial reduction in actual embedding of dirt particles, the latter tending to agglomerate at the surface of the fabric being thus rendered more accessible to removal operations, e.g., vacuuming.
Reflectance data reveal the improved cleaning ability of compositions, containing higher aliphatic alcohol, water-soluble surfactant, silica, phosphate or borax or mixtures thereof and water and formulated with or without propellant. These silica-containing compositions are superior to those which are devoid of this essential ingredient because of the abrasive action of the silica particles on the soiled fibers. In addition, full delivery of these superior cleaning compositions from containers is achieved by employing phosphate or borax or mixtures thereof as agents for preventing complexing of silica with itself and other ingredients of the composition especially surfactants.
The higher aliphatic alcohols employable in the present invention which perform the critical role of foam builder and stabilizer are alcohols which are solids at room temperature. Alcohols with less than 14 carbons atoms in the aliphatic chains are undesirable since they leave a liquid residue on the carpet fibers. Alcohols with more than 20 carbon atoms in the aliphatic chain are also not beneficial since they form poor foams. Higher aliphatic alcohols having 14 to 20 carbon atoms are the preferred ones for use in the present invention. More particularly preferred are those alcohols with 16 to 18 carbon atoms in the aliphatic chain.
Since the solid long chain alcohols agglomerate by nature, they must be dissolved or dispersed in the product in a finely divided state. If not properly prepared, the alcohol moieties agglomerate to form groupings large enough to lodge in and eventually plug up the apertures of the aerosol actuator, causing cessation of the operation, thereby preventing the product from being dispensed. It has been found, and is contemplated, as within the scope of this invention, that to insure against agglomeration of particles, the long chain alcohol must be liquefied first, then heated along with the other organic components, phosphates and/or borax in the water to a temperature at which complete solution is obtained. If this is attempted in all or most of the formula water, inordinately high temperatures (approaching the boiling point of water and resulting in manufacturing difiiculties and expenses) are required. If, however, 15 to 25% of the water of the formulation is used, these components are all in complete solution at 160 R, which is very reasonable for factory operation.
Unless the higher aliphatic alcohols are incorporated in the composition by the above stated method, clogging of the actuator and orifice of the aerosol button will oc cur. The above stated method provides sufficiently small particles of long chain alcohol which do not agglomerate and plug the actuator or orifice as would occur in compositions in which the organic alcohol is not so prepared.
The recommended content of higher aliphatic alcohol in the composition is between about to about 2% by weight of the concentrate with a range of about /z% to about 1 /2% being particularly preferred.
The water-soluble surfactants employable in the present invention may be selected from the variety of the surface active materials conventionally employed in the preparation of carpet cleaning compositions. However, the use of such materials inherently involves certain disadvantages, the more problematical being those associated with the deposition of tacky or sticky residues. Ac-
cordingly, considerable caution should be exercised as regards surfactant selection; in any event, the surfactant material should exhibit the property of drying to a friable residue capable of ready removal by vacuuming. In general, surfactants of the anionic type are preferred for use. The alkali metal alkyl sulfates and alkali metal alkoyl sarcosinates are most preferred. Surfactant materials falling within the alkyl sulfate category may be represented, according to the following structural formula:
ROSOgX wherein R comprises an aliphatic hydrocarbon group i.e., alkyl and alkenyl, such group containing preferably from 10 to 18 carbon atoms, and X represents a water-solubilizing cation e.g., alkali metal such as sodium, potassium, lithium, ammonium, substituted ammonium, amine salts, etc.
Surfactant material falling within the alkoyl sarcosinate category comprises the alkali metal alkoyl sarcosinates which may be represented according to the following structural formula:
R CON(CH )CH COOX wherein R comprises an aliphatic hydrocarbon group containing from 9 to 18 carbon atoms and wherein X has the aforedescribed significance.
Another class of surfactants found to be suitable comprise the water-soluble higher alkyl aryl sulfonates wherein the alkyl benzene sulfonates prove particularly advantageous. The higher alkyl substituent present on the aryl nucleus may be branched or straight-chained including for example tertiary octyl, decyl, lauryl, tetradecyl, etc. The sulfonate surfactant materials are likewise preferably employed in the form of their salts with water-solubilizing cations of the type hereinbefore described. Yet another class of surfactants suitable for use are derivatives of sulphosuccinic acid capable of drying residue conforming to the general structure formula:
in which R indicates a fatty acid residue or fatty alcohol residue, R indicates an alkylene grouping ioined respectively to R and to the sulphosuccinic residue via amidetype or ester-type linkages, one of Y and Z is hydrogen and the other is the group SO X, and X again has the aforedescribed significance. Although anionic type surfactants are preferred for use and in particularly alkali metal alkyl sulfates and alkali metal alkoyl sacrosinates, it will be understood that the subject invention is not limited thereto. Thus, cationic and nonionic detergents and mixtures thereof which do not leave sticky residues are likewise suitable for use.
As examples of the cationic detergents may be noted the long chain alkyl quaternary ammonium salts, e.g., cetyl pyridinium chloride.
Among nonionic compounds it is preferred to employ block copolymers of ethylene oxide and propylene oxide, such as those of the formula HO(=EtO),,(PrO) (EtO),,H, Whose molecular weight is 1000 to 2000 and wherein the ethylene oxide constitutes from 20-90% by weight. Such a material is sold under the trade name Pluronic F-68. Further suitable nonionic detersive materials may be the higher fatty acid ethanolamides and isopropanolamides wherein the alkyl radical has about 10 to 18 carbon atoms. Examples are coconut, capric, and myristic diethanolamide, monoethanolamide and isopropanolamide.
The water-soluble surfactants are used in amounts. of about 4 to 15% by weight of the concentrate composition. However, the preferred amounts being about 6-10% by weight of concentrate of the composition. Although any suitable surfactant may be used alone in the composition, mixtures of alkali metal alkyl sulfates and alkali metal alkoyl sarcosinates are preferred. Although various ratios of sulfate to sarcosinate are operable, the preferred range of proportion of sulfate to sarcosinate being about 1:3 to about 3:1. It is preferred to have the sulfate present in greater proportion than the sarcosinate and in particular the ratio of 3 :1 is eminently preferred.
The silica material preferred for use in accordance with the present invention has an average particle size ranging from about 0.007 to about 5 microns with a range of about 0.01 to about 2 microns being particularly preferred and most particularly preferred is a range of about 0.012 to about 0.05 micron. The density of the suitable silicas are in the range of about 2 to about 16 lbs./ cu. ft. and more preferably 2 to about 6 lbs. cu. ft.
Colloidal silica is the ingredient of choice. It is available commercially in a wide variety of grades and forms depending upon the process of manufacture employed. Thus, the silica may be of the pyrogenic type, a suitable representative including Cab-O-Sil available commercially from the Cabot Corporation. A precipitated type of colloidal silica suitable for use herein is available commercially from the Philadelphia Quartz Company under the trademark designation Quso, suitable synthetic silicas include for example amorphous silica gel available commercially from W. R. Grace Company under the trademark designation Syloid. In general, the particle size of the pyrogenic and precipitated silicas falls within the lower portion of the range stated while the synthetics are usually provided in the large particle size range. Also suitable for use is aluminum oxide having the appropriate particle size and density to provide similar effects as does silica.
In order to assure the obtention of optimum results, it is recommended practice to utilize the silica material in amounts ranging from about 0.75% to about 5% by weight of concentrate. Silica in amounts less than 0.75 would have minimal effect and amounts greater than about 5% are difiicult to disperse and may cause clogging of the actuator and orifice of the button of the aerosol container. To achieve maximum effects from the silica and to lessen clogging problems, the preferred silica content of the cleansing composition is about 1 to about 2% by weight of concentrate.
The phosphates employable in the present invention are Water-soluble orthophosphates, metaphosphates, pyrophosphates, tripolyphosphates, and mixtures thereof, in the form of either their anhydrous or hydrate salts. The utiliza'ble water-soluble orthophosphates have the general formula M H PO wherein M is a univalent alkali metal selected from the group consisting of sodium, potassium, lithium and ammonium, and wherein at is an integer from 1-3 and y is an integer from 1-2. Some examples of the preferred orthophosphates are sodium orthophosphate (Na HPO ammonium dihydrogen phosphate L Q Q,
potassium monohydrogen phosphate (K HPO and mono-lithium dihydrogen phosphate (LiH PO The most preferred orthophosphate phosphate is disodium monohydrogen phosphate (Na HPO The Water-soluble metaphosphates, which the invention makes use of, have the general formula (MPO wherein M is a univalent metal selected from the group consisting of sodium, potassium and ammonium, and x is an integer from 34. The metaphosphates are ring compounds. The trimetaand tetrameta phosphates have been isolated in large amounts. The trimetaphosphate (x=3) has a six-membered ring of alternate phosphorus and oxygen atoms, and the tetrametaphosphate (x=4) has an eight-membered ring.
The useful water-soluble pyrophosphates have the general formula MxH pgoq wherein M is a univalent metal selected from the group consisting of sodium, potassium and ammonium and x is an integer from 1-4 and y is an integer from 0-3. The preferred salts are tetrasodium pyrophosphate and disodium dihydrogen pyrophosphate.
The Water-soluble tripolyphosphate which are suitable for use in the invention have the general formula M 1 0 wherein M is a univalent metal selected from the group consisting of sodium, potassium, and ammonium. The preferred salt being sodium tripolyphosphate (Na P O Although the general formulas covering the suitable water-soluble phosphates do not indicate the presence of the water of crystallization for the phosphates for the purposes of the present invention, both the anhydrous and hydrate (water of crystallization present) forms are employable.
The effective amount of water-soluble alkali metal phosphates for preventing hard-gel formation is dependent upon the particular ingredients present. However, with regard to the best mode contemplated by the inventors for carrying out their invention, it is preferred to employ the water-soluble phosphates in the amounts ranging from about 0.5 to about 5% by Weight of the concentrate, i.e., all components except propellant. The preferred range being about 0.5% to about 3% by weight and most preferred being /2-2.
The present invention also relates to the use of borax in place of the water-soluble phosphates, to prevent the formation of hard, gelatinous sediment in containers containing the above described cleaning compositions. The retarding of hard, gel formation by mixtures of borax and Water-soluble alkali metal phosphates comes within the scope of the invention. Borax is sodium tetraborate and both the decahydrate (Na B O -l0H O) and pentahydrate (Na B O -5H O) forms of sodium tetraborate are effective for the purposes of the invention. Sodium tetraborate pentahydrate is preferred since it is less likely to change Weight by loss of Water.
The effective amount of borax in cleaning compositions depends upon the particular ingredients present, but with regard to the best mode of carrying out the inventors invention amounts ranging from about 0.5% to about 4% are preferred depending upon Whether the pentahydrate salt or the decahydrate salt is employed. A larger percentage of decahydrate is required since it has more water of crystallization then the pentahydrate. The preferred range is about 1% to 3% and most preferred is about 2% of the sodium borate pentahydrate.
In formulating the concentrate of the compositions of the present invention, the quantities of water employed vary from about 65 to about 95% by weight of concentrate. The concentrate of the present invention is employed in amounts of about to about by Weight of the total composition.
The preferred cleaning compositions of the present invention are provided in the form of an aerosol. In formulating such compositions, the quantity of propellant used is about 5 to about 15% by weight of total composition. It was found that the liquefied has propellant isobutane provides the desirable low pressure sufficient to expel the composition from the container and also provides optimum control over the nature of spray upon discharge of the composition. Although isobutane is the propellant of choice, propellants which are normally gaseous, liquefied materials selected from the group consisting of saturated aliphatic hydrocarbons containing from 2-4 carbon atoms, halogenated hydrocarbons containing from 1-2 carbon atoms and mixtures thereof are suitable for use. Examples of these are propane, butane, trichloromonofiuormethane, dichlorodifiuoromethane, trichlorotrifiuoroethane and dichlorotetrafiuorethane.
Fluorescent brightening agents may also be added to the cleaning compositions. Some examples of suitable brighteners are tetra-anilino stilbene, dimorpholino dianilino stilbene, diethanolamine dianilino stilbene, triazo stilbene, oxazole, and dialkylaminocoumarin.
It is to be understood that other optional ingredients of conventional types including preservatives, germicides, anticorrosion agents, etc. may be incorporated in the composition. The amount of any such ingredient employed is not of critical import although recommended practice would suggest its use in small amounts i.e., from to 1% by Weight of total composition. It will be understood of course that optional ingredients in addition to those specifically enumerated may be employed in the composition provided herein, the salient requirement being, of course, that any such ingredient to be completely devoid of any tendency to deleteriously affect or otherwise degrade the properties and characteristics of the parent composition.
The compositions of the present invention are particularly and beneficially adapted for use in the cleansing of formed textile fabrics and more particularly to heavy durable fabrics having a nap or pile. Such compositions are particularly advantageous in the treatment of rugs and carpets. In any event, the formed textile fabric may be of vegetable, synthetic or animal origin including mixtures of same. The term synthetic fabrics as employed in the context of the present invention has reference to a Wide variety of materials among which may be mentioned viscose rayon, acetate rayon, nylon, as well as fibers, derived from polyester and acrylic type polymers.
In practice, the cleaning composition is applied to the surface to be treated imparting a layer of foam thereto. A wet sponge containing water is used to spread the foam evenly. The foam is worked until it disappears. The treated area is allowed to dry, then vacuumed to remove dried cleaner and loosened dirt. There is no need for application of heat or other excess energy.
The following examples are given for purposes of illustration only and do not constitute a limitation on the present invention. All percentages are by weight.
EXAMPLE NO. 1
Ingredients (Concentrate): Percent by Weight Sodium lauryl sulfate 3.50 Sodium lauroyl sarcosinate 3.50 Cetyl alcohol 1.50 Colloidal silica 2:00 Disodium hydrogen phosphate 2.00 Fluorescent Whitening agent 0.01 Anti-corrosion agent 0.10 Water 87.39
EXAMPLE NO. 2
Ingredients (Concentrate): Percent by Weight 8 EXAMPLE NO. 4
Ingredients (Concentrate): Percent by weight Sodium lauryl sulfate 3.50 Sodium lauroyl sarcosinate 3.50 Cetyl alcohol 1.50 Colloidal silica 2.00 Sodium tripolyphosphate 2.00 Brightening agent 0.01 Anti-corrosion agent 0.10 Water 87.39
EXAMPLE NO. 5
Ingredients (Concentrate): Percent by weight Sodium lauryl sulfate 3.50 Sodium lauroyl sarcosinate 3.50 Cetyl alcohol 1.50 Colloidal silica 2.00 Sodium tetraborate pentahydrate 2.00 Brightening agent 0.01 Anti-corrosion agent 0.10 Water 87.09
EXAMPLE NO. 6
Ingredients (Concentrate): Percent by weight Sodium lauryl sulfate 3.50 Sodium lauroyl sarcosinate 3.50 Cetyl alcohol 1.50 Colloidal silica 2.00 Sodium tetraborate decahydrate 3.00 Brightening agent 0.01 Anti-corrosion agent 0.10 Water 86.39
EXAMPLE NO. 7
To prepare the aerosal cleaning compositions any of the concentrates from Examples 1-7 can be used as indicated in Example No. 8.
EXAMPLE NO. 8
Aerosal composition: Percent by weight Concentrate [anyone recited in Examples 1-7] 9O Propellant [isobutane] 10 The above formulations are adjusted to a pH of about The above formulations are adjusted to a pH of about 9.2, however a range of pH of 8.5-9.5 is suitable for practice of this invention. A- composition of low pH is a less efficient cleaner and also causes can corrosion.
It has further been found that certain of the fluorescent brighteners, which improve the appearance of carpeting further than the cleaning process, cannot be dissolved in the composition as described. For these, it becomes necessary to first liquefy the solid long chain alcohol, dissolve the brightener therein, and then add this to the organicwater mixture at F. as previously described.
The composition of the present invention provides superior cleaning activity while imparting to the carpet surface exceptional resistance to soiling despite immediate resumption of traffic. Also provided is a cleaning composition which does not overly wet the carpet backing, provides fast drying of the carpets by preventing water drainage and facilitates water evaporation.
More particularly, the present invention provides cleaning compositions which are free from the formation of hard, gelatinous sediment in the containers so that full delivery of these superior cleaning products is obtained.
Although the present invention has been described and illustrated, it is understood that modifications and variations of compositions and particulars are contemplated within the scope of the appended claims.
What is claimed is:
1. A cleaning composition adapted for shampooing carpets and the like consisting essentially of 4 to 15% by weight of a water soluble, organic surface active agent selected from the group consisting of anionic, nonionic and cationic detergents, 0.25 to 2% by Weight of an aliphatic (314-020 fatty alcohol, 0.75 to 5% by weight of finely divided water insoluble silica having a particle size ranging from about 0.007 to about 5 microns, 0.5 to 5 percent by weight as a means for preventing the formation of hard gelatinous sediment, said means being a compound selected from the group consisting of water soluble alkali metal phosphates, borax and mixtures there of, and 65 to 95 percent by weight of water.
2. A cleaning composition according to claim 1 wherein said siliceous material is a colloidal silica.
3. A cleaning composition according to claim 1 wherein said Water-soluble phosphate is selected from the group consisting of alkali metals of orthophosphate, metaphosphate, pyrophosphate, and tripolyphosphate and said alkali metals are selected from the group consisting of sodium, potassium, lithium, ammonium and mixtures thereof.
4. A cleaning composition according to claim 1 wherein said borax is the pentahydrate of sodium tetraborate.
5. A cleaning composition according to claim 1 in the form of an aerosol composition comprising the composition of claim 3 and a normally gaseous liquefied propellant in a container.
6. A cleaning composition according to claim 5 wherein said water-soluble phosphate is selected from the group consisting of alkali metals of orthophosphate, metaphosphate, pyrophosphate, and tripolyphosphate and said alkali metals are selected from the group consisting of sodium, potassium, lithium, ammonium and mixtures thereof.
7. A cleaning composition according to claim 5 wherein said borax is the pentahydrate of sodium tetraborate.
8. A cleaning composition according to claim 7 wherein said agent for preventing hard, gelatinous sediment formation is a mixture of said water-soluble phosphate and borax.
References Cited UNITED STATES PATENTS 1,753,395 4/1930 Wilkes 252524 2,344,671 3/1944 'Bertsch 252364 2,673,841 3/1954 Reinhard 252109 2,913,418 11/1959 Johngen et al. 252163 FOREIGN PATENTS 998,495 7/ 1965 Great Britain 25288 OTHER REFERENCES Bennett, The Chem. Formulag, vol. 13 (1967), Chem. Publ. 00., p. 381.
Rose, The Cond. Chem. Dict., 7th ed. (1966), Reinhold Publ. 00., p. 5-18.
Kirk-Othmel, Encyclopedia of Chem. Techn., vol. I (1963), p. 555.
WILLIAM E. SCHULZ, Primary Examiner US. Cl. X.R. 25288, 139,