US 3202714 A
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United States Patent .0
- 3,202,714 UXY CQNTAHJTNG TERTEARY AMENE (BXHDES Roger E. Zimmerer, Springfield Township, Hamilton County, and Howard F. Drew, Wyoming, Ohio, assignors to The Procter a Gamble (Iompany, Cincinnati, Qhio, a corporation of Uhio No Drawing. Filed Dec. 4, 1961, Ser. No. 156,9? 6 Claims. (Cl. 260-584) This invention relates to novel tertiary amine oxide detergents and detergent compositions containing them.
in the constant improvement of organic detergent compounds, certain features have been found to be highly desirable. These features include resistance toward the ingredients imparting hardness to water, a high degree of detergency, and capacity for solubilization of hard water soaps, such as calcium soap. Although there are a number of organic detergents which have these characteristics, detergent compounds having additional desirable characteristics find a wider scope of application.
Thermal stability is a hi hly desirable property which is lacking in many detergents. Such stability is particularly desirable when detergents are subjected to heat during use or processing, as for example, in spray drying granular detergent compositions.
Another advantageous property for an organic detergent is a low degree of hygroscopicity which results in improved crystallinity. When detergent surface active agents which are hygroscopic are used in bar or granular cool water to retain their crease resistant properties.
Wool garments should be washed in cool water. locations warm or hot Water is not available.
It is a principal object of this invention to provide organic detergents and detergent compositions which have excellent detergency characteristics as Well as high thermal stability and a low degree of hygroscopicity. It is another important object to provide detergents and detergent compositions which have these characteristics and also have a high degree of detergency in cool Water.
In some It was found that these and other objects are achieved i in a novel class of tertiary amine oxides having the structure set forth below and in detegrent compositions containing such compounds, preferably in solid form, as hereinafter more fully described.
The amine oxides of this invention are:
Inthe above formulas, R is an alkyl, 2-hydroxyalkyl, 3-hydroxyalky1 or 3-alkoxy-2-hydroxypropyl radical in which the alkyl and alkoxy, respectively, range from 10 to 18 carbon atoms in chain length, R and R are each methyl, ethyl, propyl, isopropyl, 2-hydroxyethyl, 2-hydroxypropyl or 3-hydroxypropyl groups and at least one of the R and R radicals contains a hydroxy group. The class of compounds described above will hereinafter be referred to more simply as R1R2R3N O.
Examples of the compounds of this invention are bis(2-hydroxyethyl)dodecylamine oxide, bis(2-hydroxyethyl)-2-hydroxy tetradecylarnine oxide, (2-hydroxyeth-.
yl)methyltetradecylamine oxide, bis(3-hydroxypropyl)- 3-hydroxyhexadecylamine oxide, (2 -hydroxyp1'opyl)-2- hydroxyoctadecylpropylamine oxide, bis(2-hydroxyethyl)- 3-hydroxyhexadecylamine oxide, bis(2-hydroxypropyl)do decylamine oxide, bis(Z-hydroxyethyl)-3-hydroxydo'decy-lamine oxide, bis(2-hydroxyethyl)-2-hydroxydodecylamine oxide, N,N-bis(2 hydroxyethyl) 3-dodecoxy-2-hydroxypropylamine oxide and N-methyl-N-(2-hydroxyethyl)-3 tetradecoxy-2-hydroxypropylamine oxide.
Tertiary amine oxides as a broad class of compounds are known. It was surprising to find, however, that the particular trialkylamine oxides containing particularlyplaced hydroxy groups as described above (i.e., a hydroxy group in R and/ or R have such highly desirable properties for use as organic detergents, i.e., improved hygroscopicity, thermal stability and cool water detergency characteristics.
It appears that only certain tertiary amine oxides have the aforementioned desirable characteristics; in these certain amine oxides, R R and R must be as described above. If the alkyl or allroxy in R is longer in chain length than 18 carbon atoms or shorter in chain length than 10 carbon atoms, desired detergency is not obtained. Likewise, if R and R contain more than 3 carbon atoms, such characteristics are not obtained. Either R or R must contain a hydroxy group in the 2 or 3 position, Whether or not R contains a hydroxy group, in order to achieve improved thermal stability, hygroscopicity and, especially, cool-water detergency characteristics. These properties are particularly outstanding when both R and R contain a hydroxy group. containing hydroxymethyl groups are not stable.)
In particular, those tertiary amine oxides wherein R is a C C alkyl, C -C Z-hydroxyalkyl, C C 3- hydroxyalkyl or C -C 3-alkoxy-2-hydroxypropyl radical and both R and R are 2-hydroxyethyl radicals have cool water detergency properties markedly superior to conventional organic detergent active ingredients such as sodium' dodecylbenzenesulfonate (the dodecyl group being derived fromtetrapropylene). Especially outstanding is bis(2- hydroxyethyl)dodecylamine oxide; this compound also has excellent sudsing properties.
As regards the compounds in which there is an hydroxy group in the long" chain R radical, hydroxy groups in the 2 or 3 position in R provide improved skin-mildness, thermal stability and hygroscopicity characteristics (compared to an unsubstituted 'R alkyl group). The improved mildness, thermal stability and hygroscopicity characteristics of amine oxide compounds containing hydroxy groups in R but not in R or R is set forth in copending application of Howard F. Drew, Serial No. 156,993, tiled concurrently herewith. The improved thermal stability and hygroscopicity characteristics provided by hydroxy groups in R are in addition to these characteristics which are provided by hydroxy groups in R and/ or R Thus, the mildness, hygroscopicity and thermal stability characteristics of the tertiary amine oxides which have a hydroxy group in all three alkyl radicals (e.g., bis(2- hydroxyethyl)-2-hydroxydodecylamine oxide and N,N- bis(2-hydroxyethyl)-3-dodecoxy-2 hydroxypropylamine oxide) are better than those compounds which contain hydroxy groups only in the R and/ or R radicals or in those compounds which contain no hydroxy groups. Improved cool water detergency is, however, dependent on the presence of hydroxy groups in R and/ or R 7 In tertiary amine oxides of this invention, the alkyl or alkoxy in the R group can be derived from naturally occurring fats and oils or from synthetic sources. Mixtures of amine oxides are very suitable wherein the alkyl or alkoxy inR varies in chain length in the C to C (Tertiary amine oxidesrange, as for example, the alkyl or alkoxy groups derived from coconut fatty alcohol (or distilled coconut fatty alcohol). Those amine oxides in which the alkyl or alkoxy in R ranges from 12 to 14 carbon atoms are preferred. The 3-alkoxy-2-hydroxypropyl R radical has the following general formula:
R 011233110 Hrwherein R ranges from 10 to 18 carbon atoms in chain length.
The tertiary amine oxides of this invention can be prepared, in general, by oxidizing the corresponding tertiary amine. See, for example, British Patent 437,566. The corresponding tertiary amine, in general, can be prepared by alkylating, with an appropriate long chain alkyl compound, the appropriate secondary amine. The examples explain in detail such reactions. The preparation of alkyl glycidyl ethers (a source of the 3-alkoxy-2-hydroxypropyl R is described in Canadian Patent 582,404 and U.S. Patent 2,989,547.
Compounds of this invention are useful per se as detergents and surface active agents. Desirably they are used with other materials to form detergent compositions, particularly solid form compositions as for example, bar, flake, granular or tableted granular compositions. (The tertiary amine oxide of this invention can also be used to make liquid detergent compositions.) Such detergent compositions can contain from about 5% to about 80% of the tertiary amine oxides of this invention and from about 95% to about 20% of anionic organic detergents, nonionic organic detergents, water soluble inorganic alkaline builder salts, water soluble organic alkaline sequestrant builder salts or mixtures thereof.
Granular or flake detergents preferably contain about 5% to about 50% of the amine oxides of this invention and from about 95% to about 50% normally solid, water soluble inorganic alkaline builder salts, or water soluble organic alkaline sequestrant builder agents. Bar formulations contain about 5% to about 50% of the amine oxides of this invention when used with anionic detergents, such as a soap base, and, if desired, alkaline inorganic or organic builders or inert fillers. Bar formulations can contain about 40% to about 80% of the amine oxides of this invention as the only detergent component, if desired, and the balance inert fillers or builders.
Anionic organic detergents used alone or in admixture include both the soap and non-soap detergents. Examples of suitable soaps are the sodium, potassium, ammonium and alkylolammonium salts of higher fatty acids (C C Particularly useful are the sodium and potassium salts of the mixtures of fatty acids derived from coconut oil and tallow, i.e., sodium or potassium tallow and coconut soap. Examples of anionic organic non-soap detergents are: alkyl glyceryl ether sulfonates; alkyl sulfates; alkyl monoglyceride sulfates or sulfonates; alkyl polyethenoxy ether sulfates; acyl sarcosinates; acyl esters of isethionates; acyl N-methyl taurides; alkylbenzenesulfonates; alkyl phenol polyethenoxy sulfonates. In these compounds the alkyl and acyl groups, respectively, contain 10 to 20 carbon atoms. They are used in the form of water soluble salts, the sodium, potassium, ammonium and alkylol-ammonium salts, for example. Specific examples are: sodium lauryl sulfate; potassium N-methyl lauroyl tauride; triethanolammonium dodecylbenzenesulfonate. I
The examples of nonionic organic detergents are: polyethylene oxide condensates of alkyl phenols wherein the alkyl group contains from 6 to 12 carbon atoms (e.g., 5- octylphenol) and the ethylene oxide'is present in a molar ratio of ethylene oxide to alkyl phenol in the range of 10:1 to :1; condensation products of ethylene oxide with the product resulting from the reaction of propylene oxide and ethylene diamine wherein the molecular weight of the condensation products range from water.
5000 to 11,000; the condensation product of from about 5 to 30 moles of ethylene oxide with one mole of a straight or branched chain aliphatic alcohol containing from 8 to 18 carbon atoms (e.g., lauryl alcohol).
Water soluble inorganic alkaline builder salts used alone or in admixture are alkali metal carbonates, borates, phosphates, polyphosphates, bicarbonates and silicates. (Ammonium or substituted ammonium salts can also be used.) Specific examples of such salts are sodium tripolyphosphate, sodium carbonate, sodium tetraborate, sodium pyrophosphate, sodium bicarbonate, potassium tripolyphosphate, potassium pyrophosphate, sodium hexametaphosphate, sodium sesquicarbonate, sodium monoand di-ortho phosphate and potassium bicarbonate. Such inorganic builder salts enhance the detergency of the subject amine oxides.
Examples of water soluble organic alkaline sequestrant builder salts used alone or in admixture are alkali metal, ammonium or substituted ammonium amino polycarboxylates, e.g., sodium and potassium ethylenediaminetetraacetate, sodium and potassium N-(Z-hydroxyethyl)-ethylenediaminctriacetates, sodium and potassium nitrilotriacetates and sodium potassium, and triethanolammonium N-(2-hydroxyethyl)nitrilodiacetates. Other organic alkaline sequestrant builder salts which can be used are: hydroxyethylethylenediaminetriacetates; 2-hydroxyethyliminodiacetates; diethylenetriaminepentaacetates; 1,Z-diaminocyclohexanetetraacetates. Mixed salts of these polycarboxylates are also suitable. The alkali metal salts of phytic acid, e.g., sodium phytate are also suitable as organic alkaline sequestrant builder salts (see U.S. Patent 2,739,942).
Preferred detergent compositions contain about 10% to about 30% of the tertiary amine oxides of the invention and at least an equal amount of sodium tripolyphosphate. Desirably the bis(2-hydroxyethyl)alkylamine oxides wherein the alkyl radical ranges from 12 to 14 carbon atoms in chain length are used in such preferred compositions.
The detergent compositions of this invention can contain any of the usual adjuvants, diluents and additives, for example, ampholytic or zwitterionic detergents, cationic deposition agents, bacteriostatic agents, dyes, fiuorescers, oxygen or chlorine bleaches, suds builders, suds depres sors and the like.
The following are examples which illustrate the tertiary amine oxide compounds and compositions of this invention.
EXAMPLE I grams of dodecyl bromide, 260 grams of diethanolamine and 250 ml. of methanol were mixed together in a one liter bomb which was sealed and rocked for 15 hours at C. The mixture was removed from the bomb and diluted with suflicient water to obtain a 60:40 water to alcohol solvent ratio. The solution was then made basic with sodium hydroxide. The long chain alkyl derivatives in the basic mixture were extracted with petroleum ether. The petroleum ether mixture was then acidified with dilute HCl; unreacted alkyl bromide was extracted with petroleum ether. The water layer was removed and made basic. The tertiary amine in the basic water solution was extracted with ethyl ether. This reaction is represented by the following equation:
The yield of the bis(2-hydroxyethyl)dodecylamine was 98%. The material had an amine number of 208 while 205 is calculated.
55 grams of this tertiary amine were mixed with 13.6 grams of hydrogen peroxide (45.3 grams of 30% aqueous H 0 solution), 75 ml. of ethanol and 75 ml. of The mixture was heated 'at 60 C. for 7 hours with constant agitation. The solution was cooled to room temperature and excess hydrogen peroxide was The-material had the following elemental analysis compared with the calculated analysis.
Found Calculated I .4 66.1 66. o n 12.2 12.7 N 4.6 4.81 0 (by difierence) L 17. 1 16.49
In a cloth-swatch detergency. test, the bis(2-hydroxyethyl)dodecylamine oxide was substantially superior to sodium dodecylbenzenesultonate .(a widely used detergent. active for laundering compositions). This test involved Washing naturally soiled cloth (desized print cloth) in a 0.1% aqueous solution of a composition comprising 20% organic detergent compound (amine oxide being tested or the alkyl benzenesulfonate standard), 50% sodium tripolyphosphate and 30% sodium sulfate. The composition had a pH of 10.0 and the washing was done at 130 F. for 10 minutes using wash water of 7' grains per gallon hardness. The detergency effectiveness was determined by measuring the percentage of lipid soil remaining on a standard size swatch (on a dry basis) after the washing operations. The percentage of lipid soil remaining after washing with the amine oxide test composition was compared with the percentage after washing with the alkylbenzenesulfonate standard composition. 0n the basis of the percent residual lipid soil, the lower the percent, the better the detergency performance. A Tergotometer was used for the washing operation; (Tergotometer testing is described in Detergency Evaluation and Testing, by J. C. Harris, Interscience Publishers, Inc. (1954) page 60.)
The hygroscopicity of bis(2-hydroxyethyl)dodecyl amine oxide was determined by exposing dry recrystallized material in a constant 50% relativehumidity chamher at 70 F.; it had weight increases of 3% after 1 day and 6% after 7 days in this hygroscopicity test. Dimethyldodecylamine oxide had weight increases of 32% after 1 day and 30% after 7 days. It is apparent that the former compound is much less hygroscopic than the latter; thus the former compound is preferred for solid form detergent compositions. Bis(2-hydroxyethyl)dodecylamine oxide decomposed at a temperature in the range of 135 C. to 150 C. whereas dimethyl-dodecylamine oxide decomposed at 110, C. The former compoundtherefore is preferred for spraydried detergent compositions. Y f
Bis(2-hydroxypropyl)tetradecylamine oxide, bis (2-hydroxyethyl)hexadecylamineoxide and bis(2-hydroxyethyl)-stearylamine oxide can be made by processes simi lar to that described in Example I. These compounds Will havesubstantially equivalentthermal stability and hygroscopicity characteristics and the detergency efficacy will be slightly less than that of the dodecyl compounds.
The bis(2-hydroxyethyl)stearylamine oxide is especially suitable. for asolid form detergent composition-such as atoiletbar. I
' EXAMPLE II 28 grams of 1,2-epoxydodecane, 79 grams of diethanol amine and one gram of anhydrous'aluminum chloride were placed in a 300 ml. bomb. The bomb was sealed and'rocked for hours at 200 C. Thebombwas cooled and opened; the'contents were added to aqueous solution of HCl (about 2 moles). The unreacted epoxya dodecane in the acidified reaction mixture was then extracted with petroleum ether. The remaining aqueous solution was made alkaline; the tertiary. amine was then extracted from the alkaline solution with petroleum ether. Analysis of the resulting bis(Z-hydroxyethyl)-2-hydr0xydodecylamine after distillation indicated a 70% yield.
This reaction is represented by the following equation:
D.C1UH21OHOH2 HN(CH4OH)3 HC10Hz1CHCHgN(CgH OH)g (5H 20 grams of the bis(Z-hydroxyethyl)2-hydroxydodecyl amine were mixed with 5.1 grams of H 0 (17 grams 30% aqueous solution) and 25 ml. of ethanol. The mixture was stirred and heated at 60 C. for 5 hours and then allowed to stand overnight at room temperature. The resulting solution was then diluted with 300 ml. of water. The excess H 0 was decomposed with powdered platinum black. The mixture was filtered to remove the platinum black; the unreacted amine was extracted two times with 300 ml. of petroleum ether. The remaining aqueous solution was freeze dried to yield 20 grams of amine oxide and representing a 93% yield. The oxidation reaction is represented by the following equation:
n-C H CHCH N(C H40H) H 0 I1 CIOH21C IOHZN(CH2H4OH)2 1120 OH O The elemental analysis of this tertiary amine oxide compared with the theoretical analysis, is as follows:
Found Calculated C 62.6 62.8 H 11.3 11.6 N 4.55 4.57 O (by difference) 21.55 21.03
Bis(2-hydroxyethy1)-2-hydroxydodecylamine oxide was tested by the cloth swatch test described in Example I and found to have a detergency effectiveness substantially superior to that of sodium dodecylbenzenesulfonate and approaching the hot F.-t F.) water detergeney of sodium tallow alcohol sulfate which is one of the best commercially used laundry detergent active ingredients.
Bis(2-hydroxyethyl)-2-hydroxydodecylamine oxide had Weight increases -of 1% (1 day and 7 days) in the hygroscopicity test described in Example I and decomposed at a temperature in the range of 135 C. to C.
' EXAMPLE I11 One mole of diethanolamine (420 grams) was reacted with one mole of alkyl glycidyl ether (1020 grams), wherein the alkyl group was derived from distilled coconut oil fatty alcohol (2% C 66% C 23% C 9% C at 300 F. for 1%. hours at atmospheric pressure. The reaction is represented by the following equation: 1
540 grams of the resulting N, N-bis(2-hydroxyethyl) 3-coconut alkoxy-Z-hydroxypropylamine was reacted with 255 grams of 30% aqueous hydrogen peroxide and 1205 grams of water at F for 1 /2 hours. The excess hy-' drogen peroxide was allowed to decompose under room storage conditions, The resulting. N,N-bis(2-.hydroxyethyl)-3-coconutalkoxy-Lhydroxypropylamine oxide had I excellent detergency characteristics, particularly. in built detergent formulations used in"80 F. Wash water. The
and thermal stability. It is also substantially milder to 7 the human skin as compared to unsubstituted amine oxide such as dimethyldodecylamine oxide.
In addition to the cloth swatch test described in Example I, the detergency of the amine oxides of this invention was evaluated by washing naturally soiled white dress shirts. Shirts were worn by male subjects under ordinary conditions for two normal working days. The degree to which a detergent composition containing a detergent compound to be tested cleaned the collars and cuifs of the soiled shirts, relative to the cleaning degree of a similar composition containing a standard detergent compound was considered a measure of the detergency effectiveness of the test compound.
The washing solution used in the test contained 0.03% organic surface active agent and 0.06% sodium tripolyphosphate. (No fiuorescers or bleaches or antiredeposition agents were used.) The pH of the washing solution was and water of 7 grains per gallon hardness was used. A conventional, agitator-type washer was used. The detergent compound in the standard detergent composition was sodium dodecylbenzenesulfonate, the most commonly used organic detergent compound in heavy duty laundry detergent compositions. The test detergent composition contained the detergent compound to be tested, i.e., compared with the standard composition.
Under these conditions, the detergency effectiveness of bis(2-hydroxyethyl)dodecylamine oxide in wash water of 80 F. (l) was quite superior to the detergency effectiveness of sodium dodecylbenzenesulfonate at 140 F. and of dimethyldodecylamine oxide at 80 F., and(2) was markedly superior to the detergency effectiveness of sodium tallow alcohol sulfate and sodium dodecylbenzenesulfonate at 80 F.
Thus, bis(2-hydroxyethyl)dodecylamine oxide showed surprising cool water detergency. Similar results are obtained with his (2 hydroxyethyl) 2 hydroxytetradecylamine oxide, bis(2 hydroxyethyl) 2 hydroxydodecylamine oxide and N,N-bis(2-hydroxyethyl)-3-dodecoxy-2- hydroxypropylamine oxide.
Similar comparative results are obtained if, in the white shirt detergency test, an organic alkaline sequestrant builder salt, sodium ethylenediaminetetraacetate or potassium nitriloacetate, is used instead of the sodium tripolyphosphate.
Compounds wherein only one of the short chain N-substituents contain hydroxy groups, e.g., (2-hydroxyethyl)- dodecylmethylamine oxide, also show improved cool water detergency over the corresponding unsubstituted compounds and dodecylbenzenesulfonate but not to as great a degree as the bis(2-hydroxyethyl) compounds.
The cool water detergency of those tertiary amine oxides of this invention wherein R and/or R (preferably both) contain a hydroxy group is best seen in aqueous washing solutions where the temperature is in the range of about 40 F. to about 95 F., the concentration of the active amine oxide compound is in the range of about 0.005% to about 0.5% and the washing solution also contains a water soluble alkaline inorganic builder salt or organic alkaline sequestrant builder salt (as hereinbefore described) in the range of about 0.01% to about 1.0%. Improved detergency is also seen using the amine oxide compositions of this invention in tepid (lukewarm) water (up to about 115 F.).
The tertiary amine oxides of this invention can be used in effective solid form detergent compositions having im proved hygroscopicity, thermal stability and cool water detergent characteristics. They have the following formulas:
Spray-dried granular detergent Percent Bis(2-hydroxyethyl)dodecylarnine oxide 17.5 Sodium sulfate 23 Sodium tripolyphosphate 50 Sodium silicate 6 Water 3.5
Granular detergent Percent (Z -hydroxyethyl)-2-hydroxydodecyl-ethylamine oxide 10 Sodium dodecylbenzenesulfonate (the dodecyl group being derived from tetrapropylene) 10 Sodium nitrilo triacetate 50 Sodium sulfate 30 Granular detergent Bis (2-hyrd oxypropyl tetradecylamine oxide 10 Condensation product of one mole of n-onyl phenol and nine moles of ethylene oxide 10 Sodium pyrophosphate 50 Sodium carbonate 3 Trisodium phosphate 3 Sodium sulfate 24 Milled toilet bar Percent Bis(2-hydroxyethyl)alkylamine oxide, the alkyl group being derived from coconut fatty alcohol 10 Sodium coconut oil soap 15 Sodium tallow soap 65 Moisture 10 Milled toilet bar N,N bis(2 hydroxyethyl) 3 dodecoxy 2 hydroxypropylamine oxide 50 Tallow fatty acid 25 Moisture 15 Cornstarch 5 Triethanolammonium ethylenediamine tetracetate 5 While the tertiary amine oxides of this invention find particularly desirable utilization in solid form detergent compositions because of their improved hygroscopicity and thermal stability characteristics, the outstanding cool water detergency properties of the compounds provide basis for their advantageous use in liquid detergent compositions. Liquid form detergent compositions provide convenience in use, particularly for measurement and dis-. pensing operations. Liquid detergent compositions can be in the form of solutions, dispersions or emulsions. Preferably, they can contain from about 2% to about 30% of the tertiary amine oxides of this invention and from about 5% to about 40% of a water soluble inorganic alkaline builder salt or a water soluble organic alkaline sequestrant builder salt, the balance of the composition being a solvent, such as water, and/ or other liquid vehicles.
Examples of liquid detergent compositions having improved cool water detergency characteristics are as follows:
Liquid detergent What is claimed is:
1. Tertiary amine oxide compounds having the formula R R R N O, wherein R is selected from the group consisting of Z-hydroxyalkyl, 3-hydroxyalkyl and 3-alkoxy-2- hydroxypropyl radicals in which the alkyl and alkoxy, respectively, range in chain length from 10 to 18 carbon atoms, R and R are each selected from the group consisting of 2-hydroxyethy1, 2-hydroxypropyl and 3-hydr-oxypropyl radicals.
2. Bis(2 hydroxyethyl) 2 hydroxytetradecylamine oxide.
3. N,N bis'(2 hydroxyethyl) 3 tetradecoxy 2- hydroxy propylamine oxide.
4. Bis(2 hydroxyethyl) 2 hydroxydodecylamine oxide.
5. Bis(2 hydroxyethyl) 3 hydroxydodecylamine oxide.
6. N,N bis(2 hydroxyethyl) 3 dodecoxy 2 hydroxypropylamine oxide.
References Cited by the Examiner UNITED STATES PATENTS 1,993,542 3/35 Caspe 260-583 2,060,568 11/36 Graenacher et a1 260-583 References Cited by the Applicant UNITED STATES PATENTS 10 2,185,163 12/39 Ulrich.
Schoeller et a1.
FOREIGN PATENTS France.
15 CHARLES B. PARKER, Primary Examiner.
JULIUS GREENWALD, Examiner,