US 3356613 A
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Unite This patent application is a continuation-in-part application of copending application Ser. No. 494,908 filed Oct. 11, 1965, now abandoned which was a continuationin-part of Ser. No. 353,610 filed Mar. 20, 1964, now abandoned, which in turn was a continuation-in-part application of Ser. No. 180,002, filed Mar. 15, 1962, now abandoned.
This invention pertains to detergent compositions designed especially for heavy-duty laundering. More especially, this invention relates to built detergent compositions containing a detergent compound and a novel builder salt, sodium tripolyphosphate (STP), and an organic builder salt, sodium nitrilotriacetate (NTA). The invention is based on the discovery of unexpected and remarkable synergistic builder action obtained with the novel builder mixtures described hereinafter in detail.
The broad concept of built detergent compositions has been known for some time. This broad concept envisages the capability possessed by certain substances of substantially improving the effectiveness of detergent compounds. The improved or enhanced result, as evidenced by the washed articles appearing generally cleaner, is characterized as the builder effect. Compounds which perform in this manner are called builders.
The improved performance attributed to the builder may manifest itself in several ways, for instance, as increased soil removal. The word cleaning is the term used in the artto generally identify the property of soil removal. It may, on the other hand, show up in improved whiteness maintenance results. Whiteness maintenance is understood in the art to mean the capacity of a washing composition to suspend soil in solution which soil has been removed from the fabrics being washed during the washing process. If the soil, once removed from the fabric, is allowed to repedosit upon the fabric, it generally is thought to become more firmly attached than it had been previously. Such redeposited soil may be the cause of shoddy, grey appearances in fabrics laundered with inferior detergent compositions. Relatively little is known about the complex phenomenon of cleaning and Whiteness maintenance as well as the overall behavior of built detergent composition. It is suspected, however, that builders may make their greatest contribution to the washing process in the area of whiteness maintenance. The term detergency is used herein in a generic sense and is intended to embrace both cleaning and whiteness maintenance properties.
Built detergent compositions prepared specifically for laundering the wide range of fabrics generally involved in household laundering situations are termed heavy-duty detergent compositions. Such compositions rely for their effectiveness, in part, on a high proportion of builder materials being present in the composition.
Building effects have been noted in connection with various inorganic alkaline salts such as alkali metal carbonates, bicarbonates, phosphates, polyphosphates and States Patent "ice silicate. Similar building properties have also hitherto been noted in connection with certain organic salts such as alkali metal, ammonium or substituted ammonium aminopolycarboxylates, e.g. sodium and potassium ethylenediaminetetraacetate, sodium and potassium N-(2-hydroxyethyl) ethylene diamine triacetate, sodium and potassium nitrilotriacetate and sodium, potassium and triethanclammonium-N-(Z-hydroxyethyl) nitrilodiacetate. Alkali metal salts of phytic acid have also been used as organic builders.
The nature of the building action, while quite widely recognized in the prior art, is not fully understood. There does appear to be some connection between the ability of a builder to soften the water which is used to make up the washing solution, and the improved results in detergency obtained when the builder is used. However, not all materials which act to sequester hardness-imparting calcium and magnesium ions perform satisfactorily as builders. Further, useful building actions with the most effective builders can be noted both above and below the point at which the builder is present in the washing solution in stoichiometric proportions to the hardness in water.
Detergency itself is a complex phenomenon believed to involve very many factors. Among the aspects of built detergency systems, with respect to which builders are thought to have useful effects, are such factors as stabilization of suspended solid soils, emulsification of soils, the surface activity of the aqueous detergent solution, the solubilization of water-insoluble materials, foaming or suds producing characteristics of the washing solutions, peptization of soil agglomerates, neutralization of acid soils, and the like, in addition to the sequestration of mineral constituents present in the washing solution. The action of different builders or mixtures of builders varies greatly. No general basis has been found or is known either as regards physical properties or in chemical structure upon which one can predict with any degree of accuracy the excellence, ranking or performance of chemical materials or mixtures thereof as detergency builders.
The effect of any given detergent composition when used in solution to perform a washing operation will vary with such factors as concentration, temperature, the nature of the soil, the nature of the active detergent ingredient, the amount of active ingredient in the solution, the ratio of builder to active ingredient, the hardness of the water and the like. It is sometimes observed that a detergent compound which itself has a low detergencyvalue may appear to be helped more by a given quantity of a given builder than a detergent which has superior detersive properties.
In the description of the present invention, the ratio of builder to active detergent in a detergent composition is conveniently expressed in parts by weight. Where a comparison is to be made between a builder material which is a mixture of ingredients in varying proportions, this is done by selecting a suitable surfactant, selecting a formulation containing a representative ratio of surfactant to a standard building ingredient, and then making up compo sitions for use by substituting portions of other builder ingredients for portions of the standard builder ingredient increase in the above noted desirable qualities associated with built detergent compositions. The synergistic building action in the detergent compositions to which this invention is addressed manfests itself in improvements in one or more or all of these qualities, but most notably in improved whiteness maintenance, as demonstrated hereinafter.
It is also an object of the invention to attain an enhanced building action especially in heavy-duty laundry detergent compositions.
It is another object of the invention to provide a synergistic builder mixture having building properties substantially greater than those obtained by either component of the mixture when used alone as a builder.
A yet further object is to provide a binary builder mixture having synergistic builder properties containing an inorganic builder salt and an organic builder salt.
Another object of the invention is to provide detergent compositions which are effective in water solutions over a Wide range of concentrations inasmuch as the conditions under which household laundry is done vary quite widely with the individual.
Still another object of the invention is to provide detergent compositions in which the proportion of active ingredient can be increased, if desired, without sacrificing building action.
It is an object of the invention to provide detergent compositions which are effective for heavy-duty laundering over a wide temperature range of the laundering solution.
According to the present invention, the foregoing and other objects are obtained, and an unexpected and synergistic building action is displayed, by builder mixtures containing a water soluble inorganic alkaline condensed polyphosphate builder salt and a water soluble organic alkaline salt of nitrilotriacetic acid. More specifically, the
builder compositions of this invention which perform in a synergistic manner are mixtures On a molar basis of the sodium salts of tripolyphosphoric and nitrilotriacetic acid. Sodium silicate is combined with these mixtures. I
The inorganic builder salts of this invention are the sodium salts of tripolyphosphoric acid, that is, sodium tripolyphosphate (STP).
Water soluble alkaline salts of nitrilotriacetic acid have the formula CHzCOOH N-CH2COOH CHzOOOH wherein a suitable cation is substituted for the acidic hydrogens in the above formula, the cation being sodium. The trisodium salt of nitrilotriacetic acid is used, referred to in the following description of Na NTA or more broadly as NTA.
It has been found that the builder mixtures of this invention containing STP and NTA exhibit important building properties With a very wide range of active detergent substances and mixtures thereof, and are also compatible with the adjuvants normally used in detergent compositions. The detergent substances include soap, anionic synthetic non-soap detergents, nonionic synthetic detergents, ampholytic synthetic detergents and zwitterionic synthetic detergents, and mixtures thereof.
Examples of suitable soaps are the sodium, potassium 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.
The other suitable detergent substances are outlined more at length as follows:
(a) Anionic synthetic non-soap detergents can be broadly described as the water soluble salts, particularly the alkali metal salts, of organic sulfuric reaction products having in their molecular structure an alkyl radical containing from about 8 to about 22 carbon atoms and a radical selected from the group consisting of sulfonic acid and sulfuric acid ester radicals. (Included in the term alkyl is the alkyl portion of higher acyl radicals. Important examples of the synthetic detergents which form a part of the preferred compositions of the present invention are the sodium or potassium alkyl sulfates, especially those obtained by sulfating the higher alcohols (Cg-C1 carbon atoms) produced by reducing the glycerides of tallow or coconut oil; sodium or potassium alkyl benzene sulfonates, in which the alkyl group contains from about 9 to about 15 carbon atoms, including those of the types described in United States Letters Patents Numbers 2,220,- 099 and 2,477,383 (The alkyl radical can be a straight or branched aliphatic chain); sodium alkyl glyceryl ether sulfonates, especially those ethers of the higher alcohols derived from tallow and coconut oil; sodium coconut oil fatty acid monoglyceride sulfates and sulfonates; sodium or potassium salts of sulfuric acid esters of the reaction product of one mole of a higher atty alcohol (e.g., tallow or coconut oil alcohols) and about 1 to 6 moles of ethylene oxide; sodium or potassium salts of alkyl phenol eth ylene oxide ether sulfate with about 1 to about 10 units of ethylene oxide per molecule and in which the alkyl radicals contain from 8 to about 12 carbon atoms; the reaction product of fatty acids esterified with isethionic acid and neutralized with sodium hydroxide where, for example, the fatty acids are derived from coconut oil; sodium or potassium salts of fatty acid amide of a methyl tauride in which the fatty acids, for example, are derived from coconut oil; sodium and potassium salts of SO sulfonated C1044 a olefins and others known in the art, a number being specifically set forth in United States Letters Patents Numbers 2,486,921, 2,486,922 and 2,396,278;
(b) Nonionic synthetic detergents can be broadly defined as compounds produced by the condensation of alkylene oxide groups (hydrophilic in nature) with an organic hydrophobic compound, which may be aliphatic or alkyl aromatic in nature. The length of the hydrophilic or polyoxyalkylene radical which is condensed with any particular hydrophobic group can be readily adjusted to yield to a water soluble compound having the desired degree of balance between hydrophilic and hydrophobic elements.
As an example, a class of nonionic synthetic detergents is made available on the market under the trade name of Pluronic. These compounds are formed by condensing ethylene oxide with an hydrophobic base formed by the condensation of propylene oxide with propylene glycol. The hydrophobic portion of the molecule which, of
course, exhibits water insolubility, has a molecular weight of from about 1500 to 1800. The addition of polyoxethylene radicals to this hydrophobic portion tends to increase the water solubility of the molecule as a Whole and the liquid character of the product is retained up to the point Where polyoxyethylene content isabout 50% of the total Weight of the condensation product.
Other suitable nonionic synthetic detergents include:
(1) The polyethylene oxide condensates of alkyl phenols, e.g., the condensation products of alkyl phenols, having an alkyl group containing from about 6 to 12 carbon atoms in either a straight chain or branched chain configuration, with ethylene oxide, the said ethylene oxide being present in amounts equal to 5 to 25 moles of ethylene oxide per mole of alkyl phenol. The alkyl substituent in such compounds may be derived from polymerized propylene, diisobutylene, octene, or nonene, for example.
(2) Those nonionic synthetic detergents derived from the condensation of ethylene oxide with the product resulting from the reaction of propylene oxide and ethylene diamine. For example, compounds containing from about 40% to about polyoxyethylene by weight and having a molecular weight of from about 5,000 to about 11,000 resulting from the reaction of ethylene oxide groups with a hydrophobic base constituted of the reaction product of ethylene diamine and excess propylene oxide, said base having a molecular weight of the order of 2,500 to 3,000, are satisfactory.
(3) The condensation product of aliphatic alcohols having from 8 to 22 carbon atoms, in either straight chain or branched chain configuration, with ethylene oxide, e.g., a coconut alcohol-ethylene oxide condensate having from 5 to 30 moles of ethylene oxide per mole of coconut alcohol, the coconut alcohol fraction having from to 14 carbon atoms.
(4) Long chain tertiary amine oxides corresponding to the following general formula, R R R N- O, wherein R is an alkyl radical of from about 8 to about 18 carbon atoms, and R and R are each methyl or ethyl radicals. The arrow in the formula is a conventional representation of a semi-polar bond. Examples of amine oxides suitable for use in this invention include dimethyldodecyl amine oxide, dimethyloctylamine oxide, dimethyldecylamine oxide, dimethyltetradecylamine oxide, dimethylhexadecylamine oxide.
(5) Long chain tertiary phosphine oxides corresponding to the following general formula RR'R"P O wherein R is an alkyl, alkenyl or monohydroxyalkyl radical ranging from 10 to 18 carbon atoms in chain length and R and R" are each alkyl or monohydroxyalkyl groups containing from 1 to 3 carbon atoms. The arrow in the formula is a conventional representation of a semi-polar bond. Examples of suitable phosphine oxides are: dodecyldimethylphosphine oxide, tetradecyldimethylphosphine oxide, tetradecylmethylethylphosphine oxide, cetyldimethylphosphine oxide, stearyldimethylphosphine oxide, cetylethylpropylphosphine oxide, dodecyldiethylphosphine oxide, tetradecyldiethylphosphine oxide, dodecyldipropylphosphine oxide, dodecyldi (hydroxymethyl) phosphine oxide, dodecyldi (2-hydroxyethyl) phosphine oxide, tetradecylmethyl-2-hydroxypropyl phosphine oxide, oleyldimethylphosphine oxide, and Z-hydroxydodecyldimethylphosphine oxide.
(c) Ampholytic synthetic detergents can be broadly described as derivatives of aliphatic secondary and tertiary amines, in which the aliphatic radical may be straight chain or branched and wherein one of the aliphatic substituents contains from about 8 to 18 carbon atoms and one contains an anionic water solubilizing group, e.g., carboxy, sulfo, sulfato, phosphato, or phosphono. Examples of compounds falling within this definition are sodium-3-dodecylaminopropionate and sodium-3-dodecy1- aminopropane sulfonate.
(d) Zwitterionic synthetic detergents can be broadly described as derivatives of aliphatic quaternary ammonium, phosphonium, and sulfonium compounds, in which the aliphatic radical may be straight chain or branched, and wherein one of the aliphatic substituents contains from about 8 to 18 carbon atoms and one contains an anionic water solubilizing group, e.g., carboxy, sulfo, sulfato, phosphato, or phosphono. Examples of compounds falling within this definition are 3-(N,N-dimethyl- N-hexadecylammonio) propane-l-sulfonate and 3-(N,N- dimethyl-N-hexadecylammonio) 2 hydroxy propane-1- sulfonate which are especially preferred for their excellent cool'water detergency characteristics.
The soap and non-soap anionic, nonionic, ampholytic and zwitterionic detergent surfactants mentioned above can be used singly or in combination in the practice of the present invention. The above examples are merely specific illustrations of the numerous detergents which can find application within the scope of this invention. Other surfactants within the prescribed classes can also be used.
The foregoing detergent compounds can be made into any of the several commercially desirable composition forms, for example, grannular, flake, liquid and tablet forms.
The built detergent compositions of this invention contain as essential ingredients (a) an active detergent substance as set forth above, and (b) a builder mixture as hereinafter described in more detail.
The building action of the sodium tripolyphosphate and nitrilotriacetate are roughly equivalent on a mole for mole basis with the nitrilotriacetate possibly being slightly more effective overall. It now unexpectedly has been discovered that when these roughly equivalent builders are mixed together in certain essential and critical molar proportions very marked improvements in building efiicacy and whiteness maintenance are obtained. These proportions are illustrated and established by examples hereinafter.
Wash wear tests and visual evaluation judgments were chosen as the most realistic mode of demonstrating the builder performance of the novel builder mixtures. The results of these tests and evaluations uniquely demonstrate that synergistic building results are obtained when a nitrilotriacetate salt (NTA) is substituted for sodium tripolyphosphate (STP) on a molar percentage basis so that the molar ratio of STP to NTA is within the range of from about 4:1 to about 1:4. Optimum results are obtained within the preferred molar ratio of STP to NTA of 3:1 to 1:3.
These ratios are calculated on the basis of trisodiumnitrilotriacetate (Na NTA) and penta-sodium tripolyphosphate builder (Na P O The specific action of the builder mixtures of this invention will vary to some extent depending upon the ratio of active detergent to builder mixture in any given detergent composition. Moreover, there will be considerable variation in the strengths of the washing solutions employed by different housewives, i.e., some housewives may tend to use less or more of the detergent compositions than will others. Moreover, there will be variations in temperature and in soil loads as between washing operations. Further, the degree of hardness of the water used to make up the washing solutions will also bring about apparent differences in the cleaning power and whiteness maintenance results. Finally, different fabrics will respond in somewhat different ways to different detergent compositions. The best type of detergent composition for household use is a composition which accomplishes an excellent cleaning and whiteness maintenance effect under the most diverse cleaning conditions. The built detergent compositions of this invention are especially valuable in this respect.
The builder mixtures taught herein are very eflicient, and, in general, can be used to permit the attainment of equal detergency with a smaller total quantity of builder in relation to the total quantity of active detergent ingredient. Useful degrees of building activity may be attained in the practice of this invention with by weight ratios of active organic detergent ingredient to builder mixture of from about 2:1 to about 1:10. A preferred range of by weight ratios is 1:1 to about 1:5. Percentages herein are by weight unless otherwise specified.
Below are examples of built detergent compositions prepared according to the present invention. Each composition should be used to provide a pH within the range of 9 to 12. This calls for the addition of substantial amounts of alkaline ingredients such as sodium silicate. This additive is purposefully added at low levels, i.e., up to 6% for its known contributions to built detergent compositions, i.e., corrosion inhibition. The compositions of this invention employ sodium silicate at unusually high levels, 10% or more in order to provide, i.e., establish and maintain, a pH in this range in the aqueous washing solution. According to the present invention these compositions provide excellent cleaning and whiteness main tenance results that are far superior to those obtained with a sole STP or NTA builder ingredient, especially when hard water is used for washing or when high soil levels in the fabrics being Washed are encountered, particularly acidic perspiration or human lipid soil.
It will be understood by the worker skilled in the art that detergent compositions, including the compositions of this invention, will ordinarily contain various ingredients for special purposes. Thus, they can contain suds builders, suds depressants, anti-corrosion agents, redeposition agents, dyes, fiuorescers, perfumes and the like, without interfering with the basic characteristic of this invention. In the manufacture of liquid detergents water or alcohol vehicles or mixtures of the two, together with solubilizing agents and the like, as known in the art, can be used. These form no limitation on the invention, but are intended to be includable within the terms of claims calling for compositions consisting essentially of active ingredients and builder mixtures in accordance with the teachings herein.
The detergent compositions of this invention are preferably used to provide a pH in aqueous washing solution within a pH range of from 9 to 11, the optimum building effects are obtained within this range. Washing temperatures usually range from about 80 F. to about 200 F. Fabrics are preferably rinsed and dried after washing.
The heavy-duty detergent compositions of the present invention preferably contain from about 2% to about 40% of anionic, zwitterionic or nonionic synthetic detergent, from about 10% to about 15% sodium silicate and suflicient to provide a pH of 9 to 12, from to about 35% sodium sulfate, and from about 25% to about 65% of a mixture of sodium tripolyphosphate and sodium nitrilotriacetate, wherein the ratio of the anionic synthetic detergent to said builder mixture is from about 2:1 to about 1:10 by weight and wherein said builder mixture consists of sodium tripoly'phosphate and sodium nitrilotriacetate in a ratio of from about 4:1 to about 1:4 on a molar basis.
Within theforegoing percentages and proportions, the preferred ranges are from to 30% of the synthetic detergent, from 10% to sodium silicate, from 10% to 25% sodium sulfate and from 35% to 55% of said builder mixture with any balance being moisture. The preferred molar ratio of sodium tripolyphosphate to sodium nitrilotriacetate is from 3: 1 to 1:3.
The following examples illustrate, but do not limit the practice of this invention.
Example 1 Percent Detergent active consisting of 55% sodium tallow alkyl sulfate, 45% sodium dodecylbenzene sulfomate (the dodecylradical being derived from pro- This detergent composition offers outstanding cleaning and whiteness maintenance results. Equally excellent results were obtained when the composition was duplicated but wherein the siO zNa O ratio was changed to 1.621.
Such a composition provides a pH in water solution of about 10 and gives superior heavy-duty performance as compared with compositions in which the sole builder is either STP or Na NTA. Further improvement in performance, particularly in cool water, can be obtained by replacing the active with an equal amount of 3-(N,N- dimethyl-N-hexadecylammonio -propanel-sulfonate or 3-(N;N-dimethyl-N-hexadecylammonio) 2 hydroxypropane-l-sulfonate.
Table I below contains other examples of built detergent compositions of this invention. Each composition should be used to provide a pH in the range of 9 to 12. This calls for the addition of sodium silicate at levels of 7 Sodium silicate, percent at least 10% and sufficient to provide, i.e., establish and maintain, a pH in 'this range, preferably pH 10 or more.
TABLE I Molar Weight Active Detergent ratio of ratio of STP/NTA active] builder Sodium tallow alkyl sulfate /20 2:1 Sodium linear dodecyl benzene sulfonate 75/25 1:1 Condensate of dodecyl phenol and 10 moles of ethylene oxide 75/25 1:1 Dodecyldimethylphosphine oxide 50/50 1:52 Sodium-3-dodecy1aminopropionate 25/75 1: 5 Potassium-3-dodecylaminopropane sull'onate 20/80 1.10 3-(N,N-dimethyl-N-hexadecylammonio)- propane-l-sulfonate. 75/25 2 1 3-(N,N-dimethyl-N-hexadecylammonio)- propane-2-hydroxypropane-l-sulfonatc 50/50 1 2 Example 11 A granular spray-dried detergent providing a pH of 10 Percent Sodium linear. dodecyl benzene sulfonate 13.3 Sodium nitrilotri-acetate 9.5 Sodium tripolyphosphate 41.2 Sodium silicate (SiO :Na 0 of 1.621) 10 Sodium sulfate 11 Sodium soap of hardened, fish oil fatty acids 0.5 Sodium soap of hardened tallow fatty acids 1.5 Sodium carboxymethyl cellulose .33 Phosphonated random octadecene 0.1 Optical brightener 0.5 Moisture Bal Additional examples of the compositions of this invention are shown below in Table II, each providing a pH in washing solution in the range of 9 to 11.
TABLE II.DETERGEN'I COMPOSITIONS D etergent A 0 Sodium Dodecylbenzone Sultanate (straight ehaindodccyl), percent Condensation reaction product of one mole of tallow alcohol and 10 moles of ethylene oxide (TEm), percent.
Sodium sulfonate, percent Sodium nitrilotriacetatc (NTA), percent. Sodium tripolyphosphate (S'Il), percent Water, percent Molar ratio of SIPzNTA The sodium silicate levels in the compositions of this invention should preferably not exceed about 15% in order to avoid formation of insoluble silicate products.
As is well known in the art, the Na O content of so-. dium silicate can be increased by addition of strongly alkaline materials such as NaOI-I.
Nitrilotriacetic acid (NTA) is generally considered to be in the same general class of organic amino acid compounds as is ethylenediaminetetracetic acid (EDTA). They are thought of as being equivalents for many purposes since they do have somewhat similar chemical structures and chemical properties. It was surprising, therefore, and totally unexpected to discover that these two compounds, EDTA and NTA, are not at all equivalent to each other within the terms and scope of the present invention. EDTA does not provide synergistic builder activity when mixed on a molar basis with sodium tripolyphosphate (STP). As EDTA replaces STP on an increasing molar percentage basis, the only noticeable result is an approximate straight line improvement in builder activity.
What is claimed is:
1. A detergent composition consisting essentially of a detergent selected from the group consisting of anionic, and zwitterionic synthetic detergents and mixtures thereof, and a builder mixture and at least 10% sodium silicate and suflicient to provide a pH in the range of 9 to 12, the weight ratio of detergent to builder mixture being from 2:1 to 1:10, the builder mixture consisting of sodium tripolyphosphate and sodium nitrilotriacetate in a molar ratio of 4:1 to 1:4.
2. A detergent composition consisting essentially of: to 30% of an anionic non-soap synthetic detergent, 10% to sodium silicate and sufiicient to provide a pH in the range of 9 to 12, 10% to sodium sulfate, to of a mixture of sodium tripolyphosphate and sodium nitrilotriacetate wherein the ratio of the synthetic detergent and said builder mixture is from 1:1 to 1:5 by weight, and wherein said builder mixture consists of sodium tripolyphosphate and sodium nitrilotriacetate in a ratio of from 3:1 to 1:3 on a molar basis.
3. The composition of claim 2 wherein the synthetic detergent is a C C alkyl benzene sulfonate.
10 4. The composition of claim 2 wherein the sodium silicate has an SiO :Na O ratio of 1.6: 1.
5. The composition of claim 4 wherein the pH provided is about 10.
5 References Cited UNITED STATES PATENTS 2,777,818 1/1957 Gambill 202-108 X 2,802,788 8/1957 Flaxman 252- 10 2,855,367 10/1958 Buck 252138 2,921,908 1/1 960 McCune 252110 FOREIGN PATENTS 818,151 8/1959 Great Britain.
15 846,499 8/ 1960 Great Britain.
873,488 7/1961 Great Britain. 1,398,753 4/1965 France.
LEON D. ROSDOL, Primary Examiner. 20 S. D. SCHNEIDER, Assistant Examiner.