US 3026265 A
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United States Patent 3,026,265 SAPONACEOUS DETERGENTS George Alexander Campbell, Bramhall, and Donald Kearey Howard, Manchester, England, assignors to The Geigy Company Limited, Manchester, England, a British company No Drawing. Fiied Mar. 4, 1958, Ser. No. 718,986 Claims priority, application Great Britain Sept. 9, 1954 4 Claims. (Cl. 252117) This invention relates to improvements in saponaceous detergents, i.e. detergents based on alkali metal-fatty acid soaps. This application is a continuation-in-part of Serial No. 533,226 filed September 8, 1955, and now abandoned.
As is Well known, an alkali rnetal-fatty acid soap is a salt of one or more of the higher fatty acids with an alkali metal. The poor performance of such products in hard water is well known, and it is further known that the incorporation in a detergent based on alkali metal-fatty acid soap of a complexing agent for the metallic ion content of hard water, in particular calcium, is of material assistance in improving this poor performance.
Amino-polycarboxylic acids are known to be good complexing agents and it has been suggested that the use of an alkali metal salt of an organic complexing agent of the amino-polycarboxylic acid type, such as ethylenediamine tetra-acetic acid in association with alkali metal fatty acid soaps, might be advantageous in improving the performance in hard water of such soaps.
For example, it is pointed out in Bersworth Patent No. 2,412,943 issued December 24, 1946, that the use of the aliphatic amino-polycarboxylic acids and the alkali metal salts of said acids as a deionizing agent in hard waters in association with water-soluble soap compounds has been disclosed for example in Munz Patent No. 2,240,957 issued May 6, 1941.
It is, however, stated in the aforesaid Bersworth patent that the addition of enough of the free amino acid or of the alkali metal salt of said acid to even moderately hard water to deionize the said water is generally sulficient to cause extensive insolubilizing of the alkali metalfatty acid soap compounds and that neither the amino acid nor the alkali metal salt of the acid is miscible with the alkali metal-fatty acid soap compounds in their solid or liquid anhydrous phases or in concentrated aqueous solution; and that this limits the utility of these amino compounds materially as such compounds may not be added to or incorporated in concentrated hydrous soap solutions or mixed with anhydrous soap compounds to form bar, flake, powder products or liquid soap compositions.
Bersworth, in the aforesaid patent, goes on to say that in aqueous solution the amino acid, for example ethylene diamine tetracarboxylic acid, and caustic alkali form a plurality of acid-alkali metal salts having more than 2 but less than 4 of carboxylic acid groups neutralized by the alkali, which acid-alkali metal salts are stable in aqueous solution; and that these acid-alkali metal salts of the amino acid are highly reactive towards basic oxides, hydroxides and carbonates to deionize the same and are completely miscible in all proportions with alkali metalfatty acid soap compounds (hydrous or anhydrous) to form detergent compositions therewith that are utilizable with all types of hard, saline and hard-saline water. He therefore proposes to make a detergent composition consisting of a mixture of alkali metal-fatty acid soap compounds and 5% to 25% of the acid-tri-alkali metal salt of ethylene diamine tetracarboxylic acid.
We have ourselves found that a further difficulty is encountered if an attempt is made to incorporate substantial quantities, egg. 3% by Weight and upwards, of an alkali metal tri-salt of ethylene-diamine tetra-acetic acid (hereinafter referred to as EDTA) alone in solid alkali ice metal-fatty acid soap; the texture and other physical properties of the soap are impaired and with higher quantities, e.g. 10% by weight and upwards, it is impossible to Work the soap. Even when an alkali metal tri-salt of EDTA is used, there is still a tendency for salting-out of some part of the soap when dissolved in water.
It is well known that in the manufacture of alkali metalfatty acid soaps, the so-called neat soap, in some cases While still warm, must be Worked by subjecting it to mechanical operations such as milling, plodding, flaking and stamping. Such soaps are plastic and pass through a deformable but self-cohering state between the molten and solid states, and it is essential that they should be in this deformable but self-cohering state during such working. If additional ingredients, such as perfumes, colouring matters or sequestering agents, are to be incorporated in the soap, it is necessary to accomplish this by mechanical mixing, e.g. during one of the operations mentioned above such as that of milling or plodding. A satisfactory product cannot be obtained unless the soap remains self-cohering while it is being deformed in such operations. We have found that if an attempt is made to incorporate quantities of 10% and upwards by weight of the soap, of an alkali metal tri-salt of EDTA in an alkali metal-fatty acid soap, the soap loses its self-coherence and cannot, therefore, be worked. For example, the addition of 2.0% by weight of the soap of the sodium tri-salt of EDTA to the solid sodium salt of a higher fatty acid (i.e. a sodium soap) gives a mix which is a powder and cannot be milled.
An object of the present invention is to provide solid plastic self-coherent detergents based on alkali metal-fatty acid soaps having substantially homogeneously incorporated therein higher proportions of organic complexing agents of the amino-polycarboxylic acid type than have hitherto been possible. Another object is to provide solid, homogeneous, plastic, self-coherent detergents comprising alkali metal-fatty acid soaps and at least 10%, preferably at least 20%, by weight of the soap of water-soluble salts of ethylenediamine tetra-acetic acid. A further object is to incorporate quantities of 10% and upwards, especially at least 20%, by weight of the soap of sodium salts of ethylenediamine tetra-acetic acid in sodium soaps of higher fatty acids to give solid, substantially homogeneous, plastic, self-coherent, saponaceous detergents of high sequestering power, especially for alkaline earth metals, earth metals and heavy metals. These and other objects will be more apparent from the following description.
We have found that these objects can be achieved by incorporating in the solid alkali metal-fatty acid soap an alkylolamine tri-salt of EDTA in addition to an alkali metal tri-salt of EDTA.
Ethylenediamine tetra-acetic acid (EDTA) has the structural formula:
HOOC-CHQ. OHg-COOH N-CH'z-CHrN HOOCCH: CHz-COOH It will be apparent from this formula that the possibility exists of forming mono-, di-, triand tetra-salts.
the moving parts of the mixing machinery. The product accordingly cannot be satisfactorily worked.
It has accordingly been found impossible to make a solid, substantially homogeneous, plastic self-coherent detergent comprising alkali metal-fatty acid soap and at least by weight of the soap, of water-soluble salt of ethylenediamine tetra-acetic acid when such watersoluble salt consists of an alkali metal tri-salt alone or an alkylolamine tri-salt alone. If the alkali metal tri-salt is used alone, the soap becomes brittle instead of deformable and so cannot be worked. If the alkylolamine trisait is used alone, the soap is no longer self-coherent but becomes sticky and so cannot be worked. Nevertheless, we have found, as already stated, that the objects of this invention can be secured by incorporating in a solid alkali metal-fatty acid soap an alkylolamine tri-salt of EDTA in addition to an alkali metal tri-salt of EDTA since the soap can then be readily worked in the conventional manner;
The alkylolamines are well known compounds having the structural formula wherein:
R represents a lower alkylene group, such as ethylene or propylene,
X represents a hydrogen atom, a lower alkyl group such as methyl or ethyl, or the group HOR'- (wherein R represents a lower alkylene group, such as ethylene or propylene),
Y represents a hydrogen atom, a lower alkyl group, such as methyl or ethyl, or the group HO-R (wherein R" represents a lower alkylene group, such as ethylene or propylene).
Those alkylolamines of the general formula just given above in which X and Y are hydrogen atoms or lower alkyl groups, contain only a single alkylol radical and are therefore termed monoalkylolamines.
Those alkylolamines of the general formula just given above in which X is the group HO-R and Y is a hydrogen atom or a lower alkyl group, contain two alkylol radicals and are therefore termed dialkylolarnines.
Those alkylolamines of the general formula just given above in which X is the group HOR- and Y is the group HO contain three alkylol radicals and are therefore termed trialkylolamines.
Very many alkylolamines are known and used industrially for a Variety of purposes.
Examples of the ethanolamines (R is C H in the formula) are:
It will be apparent that all of the alkylolamines, having one basic nitrogen atom, are mono-acidic i.e. they represent the monovalent radicals of the corresponding alkylolammonium hydroxide HN(ROH) (X) (Y) OH. Accordingly they will all form salts with EDTA. These salts are Watersoluble and, like the alkali metal salts of EDTA, are good complexing agents. As already indicated, the instant invention is concerned only with the tri-salts of EDTA.
We have found, according to the present invention that there can be made a solid, substantially homogeneous plastic, self-coherent, saponaceous detergent comprising alkali metal-fatty acid soap and at least 10%, by weight of the soap, of a mixture of'alkali metal tri-salt and of alkylolamine tri-salt of EDTA, provided that the amount of alkylolarnine tri-salt is at least one-third that of the alkali metal tri-salt by weight, preferably between onethird and an equal amount by weight.
We are thus able to provide detengents based on alkali metal-fatty acid soaps which can be made and used like conventional alkali metal-fatty acid soaps but have exceptionally high complexing ability. This makes them of particular value for the decontamination of surfaces, including the body surfaces of human beings and other living animals, when such surfaces have become contaminated by heavy metals, especially radioactive materials such as fission products from an atomic pile. They are also of value for the cleansing of laboratory and industrial equipment, buildings and clothing which may have been similarly contaminated. For such decontamination it is desirable to have a detergent which contains a very high proportion of complexing agent for heavy metals.
The most convenient alkylolamine tri-salts of EDTA to employ in the present invention are those of the ethanolamines but those of any of the other alkylolamines, such as of any of those just recited, may be used. If an ethanolamine tri-salt is used, it may be the tri-salt of monoethanolamine, diethanolamine or triethanolamine or of mixtures of these. If desired, such tri-salt may be one made from commercial ethanolamine which consists of a mixture of tri- (75-80%), di- (20-25%) and mono- (about 5%) ethanolamine. Preferably, however, there is employed the triethanolamine tri-salt of EDTA, i.e. the tri-triethanolamine salt of EDTA, of the general formula:
Any of the alkylolamine salts of EDTA can readily be made by simply heating together the theoretical proportions of the alkylolamine and ethylenediamine tetraacetic acid in water, if the product is required in solid form, evaporating oflE the water. The following procedure is illustrative of the manufacture of any of the alkylolamine salts of EDTA.
Preparation of the Triez'hanolamine T ri-Salt of EDTA 292 grams of ethylenediamine tetra-acetic acid are stirred into a solution of 447 grams of triethanolamine in ml. water. The mixture is heated on a steam bath with occasional stirring, until a clear solution is obtained. The resultant solution can be used directly, but if a solid product is required, the solution is evaporated on a steam bath until a sample sets, on cooling, to a white waxy solid.
Propanolamine salts of EDTA can be made in a manner similar to that described above for making the ethanolamine salts. Any of the alkali metal tri-salts of EDTA may be used in the instant invention but prefer ably the sodium tri-salt is used. This can be made in a similar manner to the alkylolamine tri-salt, e.g. as follows:
Preparation of the Sodium T ri-Salt of EDT A 120 grams of solid sodium hydroxide are dissolved in 1 litre of water and to the resulting solution 292 grams of ethylenediamine tetra-acetic acid are added with stirring and warming. The resulting solution can be used directly but if a solid product is required the hot solution can be spray-dried. The potassium tri-salt can be made in similar manner from 168 grams of solid potassium hydroxide.
In general, 10% by weight and upwards of watersoluble EDTA salts can be satisfactorily incorporated in solid alkali metal-fatty acid soap by the customary mechanical mixing operations, such as milling or plodding, so long as at least one-quarter is in the form of the alkylolamine tri-salt and the remainder in the form of the alkali metal tri-salt. Thus, incorporation in a solid sodium soap of 10%, by weight of the soap, of the sodium tri-salt and 10%, by weight of the soap, of the triethanolamine tri-salt gives a soap which is readily workable.
The alkali metal tri-salt of EDTA and/ or the alkylolamine tri-salt of EDTA may be incorporated in the soap in the dry state or as concentrated aqueous solution; in the latter case water will be evaporated from the mixture during the customary mechanical mixing operations, such as milling or plodding.
The solid saponaceous detergents of the present invention do not show salting out on solution in water.
The invention is illustrated by, but not limited to, the following examples:
EXAMPLE 1 A toilet soap base containing 78% fatty acids, 10% of combined alkali and 12% moisture and made by saponification with caustic soda of a fatty acid mixture consisting of 75 parts good colour tallow, 25 parts coconut oil and 1 part rosin was taken in the form of soap flake. This was milled and during milling, there were added 10%, by weight of the soap, of the sodium trisalt of ethylenediamine tetra-acetic acid and 10%, by weight of the soap, of molten triethanolamine tri-salt of ethylenediamine tetra-acetic acid. The mixture milled and plodded satisfactorily. The resulting soap was a highly eificient decontaminating agent for surfaces contaminated with radio-active or other heavy metal compounds.
The product from one run was stamped into bars. product from another run was formed into flakes. forms proved eflicieut decontaminating-detergents.
It was found that the sodium tri-salt and the triethanolamine tri-salt could be added separately or together with equally satisfactory results.
It was also found that if these salts were replaced by 20%, by weight of the soap, of the sodium tri-salt alone, the mixture disintegrated into a powder when an attempt was made to work it.
The Both EXAMPLE 2 The procedure was as in Example 1 but 15% of the sodium tri-salt was used instead of 10% and of the triethanolamine tri-salt was used instead of A soap product similar to that of Example 1 was produced.
EXAMPLE 3 The procedure was as in Example 2, but the triethanolamine tri-salt was incorporated as a 60% aqueous solution instead of being molten. The resulting mixture was rather more easily workable, but the resulting soap was similar.
EXAMPLE 4 The procedure was as in Example 1 but the sodium tri-salt of ethylenediamine tetra-acetic acid was replaced by the same amount of the potassium tri-salt of ethylenediamine tetra-acetic acid. A similar result was obtained.
By the procedure of Example 1, workable soap was obtained when the triethanolamine tri-salt of ethylenediamine tetra-acetic acid was replaced by an equal amount of one of the following salts:
EXAMPLE 5 Diethanolamine tri-salt of ethylenediamine tetraacetic acid.
EXAMPLE 6 Monoethanolamine tri-salt of ethylenediamine tetraacetic acid.
EXAMPLE 7 Triisopropanolamine tri-salt of ethylenediamine tetraacetic acid.
By the procedure of Example 1, workable Soap was obtained when the sodium tri-salt of ethylenediamine tetra-acetic acid Was replaced by an equal weight of the potassium tri-salt and the triethanolamine tri-salt of ethylenediamine tetro-acetic acid W% rep-laced by an equal amount of one of the following salts:
EXAMPLE 8 Diethanolamine tri-salt of ethylenediamine tetra-acetic acid.
EXAMPLE 9 Monoethanolamine tri-salt of ethylenediamine tetraacetic acid;
EXAMPLE 10 Tn'isopropanolarnine tri-salt of ethylenediamine tetraacetic acid.
The invention is not limited to the foregoing description, but is of the scope of the appended claims.
1. A solid, substantially homogeneous, plastic, selfcoherent saponaceous detergent composition consisting essentially of sodium-fatty acid soap and from 10% to 20% by weight of said soap of a mixture of an alkali metal tri-salt of ethylenediamine tetra-acetic acid and of an alkylolamine tri-salt of ethylenediamine tetra-acetic acid, the amount of alkylolamine salt being between onethird and an equal amount of that of the alkali metal salt by weight, the alkali metal of the alkali metal tri-salt being a member selected from the group consisting of sodium and potassium, and the alkylolamine of the alkylolamine tri-salt being a compound of the general formula:
wherein R represents a lower alkylene group,
X represents a member selected from the group consisting of the hydrogen atom, lower alkyl groups and the group HOR- in which R represents a lower alkylene group, and
Y represents a member selected from the group consisting of the hydrogen atom, lower alkyl groups and the group HO- in which R" represents a lower alkylene group.
2. A solid, substantially homogeneous, plastic, selfcoherent saponaceous detergent composition as defined in claim 1 in which the alkali metal salt is the sodium tri-salt.
3. A solid, substantially homogeneous, plastic, selfcoherent saponaceous detergent composition as defined in claim 1 in which the alkylolamine salt is the triethanolamine tri-salt.
4., A solid, substantially homogeneous, plastic, selfv coherent detergent composition consisting essentially of sodium-fatty acid soap, substantially 5% by Weight of said soap of the triethanolamine tri-salt of ethylenediamine tetra-acetic acicl and substantially 15% by Weight of said soap of the sodium tri-salt of ethylenediamine tetra-acetic acid.
8 References Cited in the file of this patent UNITED STATES PATENTS Bersworth' Dec. 24, 1946 OTHER REFERENCES Sequestrene, publication of Geigy Ind. Chemical (1952), pages 1 and 37-41.