DE69328688T2 - DISPERSING AGENTS - Google Patents

Abstract

A cleaning composition contains (a) a detersive surfactant and (b) a poly(amino acid) compound or a precursor thereof, the said component (b) being protected from contact with a level of alkalinity as would cause degradation thereof. The component (b) may be stabilised by, for example, coating it with an organic acid compound or with a film-forming polymer; by agglomerating it with a controlled level of alkaline or alkaline-reacting compound (e.g. sodium carbonate); by spray-granulating it in admixture with a nonionic surfactant; by encapsulating it with a silicone-based resin; or by incorporating it in a composition that is non-alkaline. The storage stability of the compositions is thereby improved.

Description

Field of the invention

The present invention relates to the use of poly(amino acids) and derivatives thereof as dispersants, in particular in detergent compositions, e.g. in laundry detergent compositions.

Background of the invention

Polyacrylates and acrylate/maleate copolymers are commonly used as dispersants, particularly as soil suspending agents and/or anti-resoiling agents, in detergent compositions, providing important cleaning benefits. However, these polymers and copolymers are not readily biodegradable, posing potential environmental problems. Carboxymethylcellulose is biodegradable at a degree of substitution (DS) of less than 0.7, but is deficient in soil suspending properties, although it does provide some whitening benefit to detergent compositions.

EP-A-0,454,126 discloses that certain poly(amino acids) and their derivatives can be used as builders or cobuilders in the formulation of detergent compositions. These polymers, in particular those derived from aspartic acid, glutamic acid and mixtures thereof, are described as effective agents for calcium complexation and for preventing the formation of calcium carbonate crystals. These polymers are also said to have the advantage of being heat resistant, pH stable, non-toxic, non-irritating and completely biodegradable. US 4,587,033 describes polymeric acetal carboxylates which are stabilized by mixing with basic additives.

However, research by the present applicant has shown that polyaspartates or other poly(amino acid) salts incorporated into a granular detergent composition will degrade over a period of time, particularly under conditions of elevated temperature and/or high humidity (e.g., conditions of 90ºF (32.2ºC) and 80% relative humidity) such as are typical of southern European and other Mediterranean countries (and which may also be found in warehouses elsewhere). Such irreversible degradation can cause significant loss of dispersion activity during the storage period (typically up to 8 weeks) that may occur in practice. This degradation was unexpected in view of the relative strength of the amide bonds in the poly(amino acids).

Summary of the invention

The present invention provides a detergent composition comprising a poly(amino acid) compound or a precursor thereof and a detergent surfactant, characterized in that the poly(amino acid) compound or the precursor thereof is protected against contact with a level of alkalinity which would decompose it.

The present invention therefore provides a poly(amino acid) compound or a precursor thereof, which is characterized in that it is provided with a coating, encapsulated or mixed in the form of an agglomerate or granulate with at least one non-ionic surfactant or zeolite.

The present invention also provides a poly(amino acid) compound or a precursor thereof, which is characterized in that it is in the form of an agglomerate with an alkaline or alkaline-reacting material.

The present invention further provides a process for preparing a poly(amino acid) compound in the form of an agglomerate suitable for incorporation into a detergent composition, which comprises agglomerating the alkaline or alkaline reacting material with a compound which is converted to the poly(amino acid) compound under alkaline conditions, the agglomeration being effected in the presence of sufficient moisture to allow the conversion to the poly(amino acid) compound to proceed.

Description of exemplary embodiments

The term "poly(amino acid)" compound herein includes not only a poly(amino acid) per se, but also a derivative thereof, such as an amide, an ester or a salt. The poly(amino acid) may be a homopolymer or a copolymer of two or more amino acids. The amino acid may be a D-amino acid oic acid, an L-amino acid or a mixture, e.g. a racemic mixture, thereof. The amino acids include, for example, alanine, glycine, tyrosine, serine and lysine, although glutamic, carboxyglutamic and aspartic acid are preferred. Of these, aspartic acid is particularly preferred. Normally, for the purposes of formulating a detergent composition, particularly a laundry detergent composition, the poly(amino acid) is used in the form of a salt thereof, preferably an alkali metal salt and most preferably a sodium salt.

It is to be understood that the poly(amino acid) compound may be composed of a mixture of two or more compounds as appropriately described.

Also contemplated herein is the use of a precursor to a poly(amino acid) compound, with suitable precursors being compounds that are converted to a poly(amino acid) or a derivative thereof under alkaline conditions. Therefore, a preferred precursor herein is polysuccinimide, which hydrolyzes to polyaspartic acid at a pH greater than 9, with hydrolysis occurring particularly rapidly at pH values of 10 or higher. This opens up the possibility of forming the poly(amino acid) or a derivative thereof in situ in the wash liquor formed by adding the laundry detergent or other cleaning composition to water; such wash liquors typically have a pH of approximately 10.5.

The molecular weight of the poly(amino acid) compound or its precursor can be varied within wide limits. Preferably, the molecular weight ranges from 500 to 200,000, most preferably from 2,000 to 20,000.

According to the invention, a poly(amino acid) compound or precursor thereof is sufficiently stabilized against degradation to render it acceptably stable for storage. This is specifically accomplished by protecting the compound or precursor from contact with a level of alkalinity which would cause unacceptable degradation thereof. The stabilization or protection should be such that the level of degradation of the poly(amino acid) compound or precursor thereof over a storage period of 8 weeks under severe conditions (90°F (32.2°C) with 80% relative humidity) is less than 50%, preferably less than 30%, and most preferably less than 5%. A preferred method for stabilizing the poly(amino acid) compound against degradation is to apply a stabilizing coating thereto. The coating material, which should be compatible with other ingredients of the detergent composition, can be selected from a wide variety of biodegradable and non-biodegradable compounds. Of course, the coating can comprise a mixture of two or more suitable materials.

In certain preferred embodiments, the coating material is an organic acid compound, particularly one that is solid at room temperature; therefore, the organic compounds should generally have a melting point of at least 30°C, preferably a melting point of at least 40°C, and most preferably a melting point above 50°C. The organic acid compound should also be highly water soluble at room temperature, with "highly soluble" for the purposes of the present invention being defined as at least 5 g of the acid dissolved in 100 g of distilled water at 20°C. Preferably, the organic acid compound has a solubility of at least 20 g/100 g of water at 20°C, and most preferably, the organic acid compound dissolves in its own weight of water at 20°C.

Organic acid compounds suitable as coating materials for the purposes of the present invention include aliphatic or aromatic, monomeric or oligomeric carboxylic acids, preferably the monomeric aliphatic carboxylic acids. Examples of such aliphatic acid compounds are glycolic, glutamic, succinic, L-lactic, malonic, glutaric, adipic, maleic, malic, tartaric, diglycolic, carboxymethylsuccinic, citric, citraconic, itaconic and mesaconic acids; and copolymers formed from an unsaturated polycarboxylic acid (e.g. maleic, citraconic, itaconic or mesaconic acid) as one monomer and an unsaturated monocarboxylic acid, such as acrylic acid or an alpha-C1-C4 alkyl acrylic acid, as the second monomer, suitable copolymers being available from BASF under the trade names Sokalan® CP5 and CP45.

The organic acid compound may be used in admixture with other materials suitable for use in the detergent composition: for example, a coating which provides an acidic environment to the poly(amino acid) compound, citric acid or the like dissolved in a non-ionic nic surfactant. The use of gelatin as an additive is also possible. The use of a coating of a poly(amino acid) to protect a poly(amino acid) derivative is also contemplated.

The acids are generally used in amounts of 2 to 20% by weight of the coated substrate, preferably 2 to 15% by weight, particularly preferably 3 to 12% by weight and most particularly preferably 3 to 10% by weight of the coated substrate. Glycolic acid in a proportion of approximately 5% by weight of the coated substrate is a particularly preferred coating agent.

The organic acid compound may be sprayed as a molten material or as a solution or dispersion in a solvent/carrier liquid which is subsequently removed by evaporation. The organic acid compound may also be applied as a powder coating, although this is less preferred because providing a uniform layer of coating material is less easy and hence less effective.

Melt coating is a preferred technique for organic acid compounds with a melting point of less than 80ºC, such as glycolic and L-lactic acid, but is less convenient for acids with a higher melting point (e.g., higher than 100ºC), such as citric acid. For organic acid compounds with a melting point higher than 80ºC, spraying as a solution or dispersion is preferred. Organic solvents such as ethyl and isopropyl alcohol can be used to form the solutions or dispersions, although this requires a solvent recovery step to make their use economical. However, the use of organic solvents also causes safety problems such as flammability and user safety, and therefore aqueous solutions or dispersions are preferred.

Aqueous solutions are particularly advantageous where the organic acid compound has a high water solubility (e.g. citric acid) and the solution has a sufficiently low viscosity to permit handling. Preferably, a concentration of at least 25% by weight of the organic acid compound in the solvent is used to reduce the drying/evaporation load after coating is completed. The coating equipment may be any of those normally used for this purpose, such as tilt pans, rotating drums and fluidized beds.

The poly(amino acid) compound may alternatively be stabilized by means of a coating formed from a water-soluble film-forming polymer. Such polymers include water-soluble cellulose ethers, e.g. methylcellulose, ethylcellulose, hydroxyethylcellulose, methylhydroxyethylcellulose, methylhydroxypropylcellulose, carboxymethylcellulose (particularly as the sodium salt) and methylcarboxymethylcellulose (particularly as the sodium salt); water-soluble starches, e.g. corn starch or depolymerized starch; starch ethers, e.g. carboxymethyl starch, hydroxyethyl starch and methyl starch; and mixtures of any two or more of these. Sodium carboxymethylcellulose (CMC) is preferred.

Suitable film-forming polymers also include carboxylic acid homopolymers or copolymers such as polyacrylic acid, polymethacrylic acid and polymaleic acid; copolymers of acrylic acid or methacrylic acid with maleic acid, or a copolymer of maleic acid with vinyl methyl ether; and the salts, especially the sodium salts, of such polymeric acids. Preferred film-forming agents from this group are sodium polyacrylate and the sodium salts of acrylic acid/maleic acid copolymers having a weight ratio of acrylic acid:maleic acid of 10:1 to 1:1, preferably 7:1 to 2:1. These compounds may have a molecular weight of 3,000 to 150,000, preferably 5,000 to 10,000.

Another class of film-forming polymers are the carbon chain polymers with non-ionic hydrophilic groups or polyether groups, examples of which include polyvinyl alcohol, partially saponified polyvinyl acetate, polyvinylpyrrolidone, polyacrylamide and polyethylene glycol ether.

Suitable mixtures of film-forming polymers include, for example, a mixture of CMC or methylcellulose with polyacrylate or with an acrylic acid/maleic acid copolymer, or a mixture of polyethylene glycol ether with polyacrylate or an acrylic acid/maleic acid copolymer.

Another and particularly preferred method of stabilizing the poly(amino acid) compound is to formulate it as an agglomerate with an alkaline or alkaline reacting compound. Such an alkali, e.g. sodium or potassium hydroxide, although not excluded, may be unsuitable for many detergent compositions and therefore the use of an alkaline salt, e.g. a carbonate, bicarbonate or silicate, is preferred. Preferred salts are the alkali metal salts, especially the sodium salts. Of course Preferably, a mixture of two or more alkaline or alkaline reacting compounds may be used. In addition, the alkaline or alkaline reacting compound may be used in a mixture with one or more suitable materials, e.g. an anionic surfactant such as alkyl ethoxy sulfonate (AES).

Bearing in mind that polyaspartate or the like is sensitive to alkaline hydrolysis, it is all the more surprising that poly(amino acid) compounds can be made storage stable by agglomeration with an alkaline or alkaline reacting compound. However, according to one aspect of this invention, the decomposition of the poly(amino acid) compound can be inhibited by controlling the content of alkaline or alkaline reacting compound in the agglomerate: in specific preferred embodiments, there is no more than 1 mole of alkaline or alkaline reacting compound per mole of monomeric unit in the poly(amino acid) compound.

In a preferred embodiment of this invention, the alkaline or alkaline reacting compound is initially mixed with a precursor of a poly(amino acid) compound, particularly with such a precursor which converts to a poly(amino acid) compound under alkaline conditions. The agglomeration step is normally effected in the presence of sufficient water to allow such conversion to occur, and immediately after drying the agglomerates normally contain sufficient residual moisture to allow the conversion to proceed to completion if this has not already occurred. Suitable precursors include the imides of those poly(amino acids) which form such imides. Therefore, storage-stable poly(aspartic acid) or a salt thereof, in particular sodium polyaspartate, can be prepared in a simple manner by agglomerating polysuccinimide with an alkaline and alkaline-reacting compound, whereby the polysuccinimide is converted into the polyaspartic acid or polyaspartate in situ. This process is particularly advantageous because the polysuccinimide is significantly cheaper than the commercially available polyaspartate and this process already provides the latter compound in a storage-stable form suitable for incorporation into a granular (this term includes powdered) detergent composition, e.g. a laundry detergent composition.

The preferred alkaline or alkaline reacting material is sodium carbonate, which is itself a valuable component in cleaning compositions as it acts as an effective solubilizing agent. Typically, the carbonate is included in laundry detergent compositions in the form of a micronized powder; however, the use of carbonate with a larger particle size or carbonates with different particle sizes is contemplated as this reduces the surface area per unit mass and thereby reduces the rate of reaction between the poly(amino acid) compound and the carbonate.

In certain preferred embodiments, there is no more than 1 mole of alkaline or alkaline reacting compound, e.g., carbonate, per mole of monomeric unit in the precursor, e.g., the succinimide unit in polysuccinimide.

Another preferred embodiment is to form agglomerates of polyaspartic acid (or other poly(amino acid)) and sufficient carbonate (or other alkaline or alkaline reacting compound) to effect neutralization but not decomposition. The polyamino acid can be formed in situ from a suitable precursor, e.g. polysuccinimide. Other components can of course be included in such agglomerates.

The agglomeration of the poly(amino acid) compound or its precursor and the alkaline or alkaline reacting compound can be carried out using any suitable agglomeration technique and equipment when paired with suitable agglomeration aids. Such techniques, equipment and aids are well known in the detergent formulation art. Once the agglomerates are formed, they can be dried by conventional means if necessary.

Agglomeration of the poly(amino acid) compound or its precursor can be conveniently carried out in various types of high shear mixers, e.g. a Z-blade mixer, an Eirich mixer or a Lödige mixer.

The agglomerates of the invention may contain, for example, 20 to 40% anionic surfactant, 0 to 30% sodium carbonate, 0 to 50% zeolite, 0 to 15% of the poly(amino acid) compound or its precursor, 0 to 10% CMC, weighed with water. In a typical process, the agglomeration mixer is filled with the inorganic materials and the CMC, together with the poly(amino acid) compound or its precursor, and the resulting mixture is mixed with a highly active anionic surfactant (typically 50 to 85 wt.% active), suitable anionic surfactants being e.g. C45AS, LAS or TAS. Typically, the paste is added at 50 to 80ºC and the agglomeration time is typically between 1 and 15 minutes. Agglomeration may optionally be followed by a drying and cooling step. Typical physical properties of the resulting agglomerates are a density in the range of 500 to 900 g/l, an average particle size of 200 to 800 µm, a correspondingly low powder body strength and good flow properties.

Agglomeration of the poly(amino acid) compound with a non-ionic surfactant or a zeolite, or a mixture of two or more of these, is of course also possible.

Another method according to the invention for stabilizing the poly(amino acid) compound is its spray granulation in a mixture with, for example, a nonionic surfactant. Yet another method according to the invention is the encapsulation of the poly(amino acid) compound, for example using a silicone-based resin.

If appropriate, pretreatment of the poly(amino acid) compound or its precursor may be carried out. For example, the compound or precursor may be premixed with a surfactant paste prior to agglomeration, coating, spray granulation, encapsulation or the like, or it may be mixed with the surfactant in the form of an aqueous solution followed by drying to remove moisture. The latter method allows a predetermined moisture content to be achieved.

By appropriately adjusting the pretreatment, e.g. by premixing the poly(amino acid) compound or its precursor with surfactant paste, it is possible to obtain agglomerates with an excess of carbonate or another alkaline or alkaline reacting compound.

As shown below in Example 2, decomposition of the poly(amino acid) compound can also be caused by the presence of a bleach, particularly a hydrogen peroxide source. Accordingly, it is a further aspect of this invention to provide a detergent composition comprising a poly(amino acid) compound or a precursor thereof and a detergent surfactant, characterized in that the poly(amino acid) Compound or its precursor is protected from contact with a level of bleach which would cause its decomposition. The poly(amino acid) compound or its precursor may be stabilized or protected against unacceptable decomposition (as defined above) by coating, by encapsulation or by mixing, in the form of an agglomerate or granulate, with at least one other material by means analogous to those described above. In certain preferred embodiments, the poly(amino acid) compound or its precursor is included in a detergent or other cleaning composition which contains no or approximately no bleach; in such a case, depending on the level of alkaline or alkaline reacting material, further stabilization of the poly(amino acid) compound or its precursor by means of coating, encapsulation, agglomeration, granulation or the like may not be necessary, although this is not excluded.

The stabilized poly(aspartic acid) compound of the invention can be used as a dispersant (this term includes herein a clay soil suspending agent and/or an anti-resoiling agent) in solid (e.g. granular or other particulate) detergent compositions and is generally used therein at a level of 0.1 to 50 wt.%, usually at least 0.4 wt.%, preferably 1 to 15 wt.%, more preferably 2.5 to 10 wt.% and most preferably 3 to 6 wt.%. The detergent compositions generally contain one or more detergent surfactants, the total amount of which generally represents up to 70 wt.%, typically 1 to 50 wt.%, preferably 1 to 30 wt.%, more preferably 5 to 25 wt.% and especially 10 to 20 wt.% of the total composition.

Although the poly(amino acid) compounds can be included in a wide variety of cleaning compositions, e.g. for hard surfaces and other household cleaners and dishwashing compositions, they are particularly suitable for use in laundry detergent compositions, e.g. in all-purpose or heavy-duty granular laundry detergent compositions. These contain not only the stabilized poly(amino acid) compound as a dispersant and a detergent surfactant, but optionally also one or more components conventional in the art; these can be selected, for example, from a detergent builder, a bleach (particularly a source of hydrogen peroxide, e.g. sodium perborate or sodium percarbonate), a bleach activator (e.g. TAED), an enzyme, a polymeric soil-resisting agent, a chelating agent, a conventional dispersant, a brightener, a suds suppressor, a pH buffering agent, a dye, a dye transfer inhibiting agent or a pigment. It will be understood that any of the above-mentioned components, whether essential or optional, may, if desired, be composed of a mixture of two or more compounds of the appropriate description.

A wide range of surfactants can be used in the detergent compositions. A typical listing of anionic, nonionic, ampholytic and zwitterionic classes and types of these surfactants is disclosed in U.S. Patent No. 3,664,961, issued to Norris on May 23, 1972.

Mixtures of anionic surfactants are particularly suitable herein, particularly mixtures of sulfonate and sulfate surfactants in a weight ratio of 5:1 to 1:2, preferably from 3:1 to 2:3, most preferably from 3:1 to 1:1 Preferred sulfonates include alkylbenzene sulfonates having from 9 to 15, especially 11 to 13 carbon atoms in the alkyl radical, and alpha-sulfonated methyl fatty acid esters in which the fatty acid is derived from a C12-C18 fat source, preferably from a C16-C18 fat source. In any case the cation is generally an alkali metal, preferably sodium. Preferred sulfate surfactants are alkyl sulfates having 12 to 18 carbon atoms in the alkyl radical, optionally mixed with ethoxy sulfates having 10 to 20, preferably 10 to 16 carbon atoms in the alkyl radical and an average degree of ethoxylation of 1 to 6. Examples of preferred alkyl sulfates are tallow alkyl sulfate, coconut alkyl sulfate and C14-15 alkyl sulfates. The cation in each case is again generally an alkali metal cation, preferably sodium.

One class of nonionic surfactants particularly useful in the present invention are condensates of ethylene oxide with a hydrophobic moiety to provide a surfactant having an average hydrophilic-lipophilic balance (HLB) in the range of 5 to 17, preferably 6 to 14, most preferably 7 to 12. The hydrophobic (lipophilic) moiety may be aliphatic or aromatic in nature, and the length of the polyoxyethylene group condensed with any particular hydrophobic group may be readily adjusted to provide a water-soluble compound having the desired degree of balance between hydrophilic and hydrophobic elements.

Particularly preferred nonionic surfactants of this type are the primary C₄-C₁₅- Alcohol ethoxylates containing 3 to 8 moles of ethylene oxide per mole of alcohol, in particular the primary C₁₄-C₁₅ alcohols containing 6 to 8 moles of ethylene oxide per mole of alcohol, the primary C₁₂-C₁₅ alcohols containing 3 to 5 moles of ethylene oxide per mole of alcohol, and mixtures thereof.

Another suitable class of nonionic surfactants includes alkyl polyglucoside compounds of the general formula

RO(CnH₂nO)tZx

wherein Z is a moiety derived from glucose; R represents a saturated hydrophobic alkyl group having 12 to 18 carbon atoms; t ranges from 0 to 10 and n is 2 or 3 ; x ranges from 1.3 to 4, the compounds containing less than 10% unreacted fatty alcohol and less than 50% short chain alkyl polyglucosides. Compounds of this type and their use in detergents are disclosed in EP-A- 0,070,077, EP-A-0,075,996 and EP-A-0,094,118.

Also suitable as non-ionic surfactants are the polyhydroxy fatty acid amide surfactants of the formula

wherein R¹ is H, C₁₄-hydrocarbon, 2-hydroxyethyl, 2-hydroxypropyl or a mixture thereof, R² is a C₅₋₃₁-hydrocarbon, and Z is a polyhydroxyhydrocarbon having a linear hydrocarbon chain with at least 3 hydroxyl groups directly attached to the chain or an alkoxylated derivative thereof. Preferably R¹ is methyl, R² is an unbranched C₁₁₋₁₅-alkyl or alkenyl chain such as coconut alkyl or mixtures thereof, and Z is derived from a reducing sugar such as glucose, fructose, maltose, lactose in a reductive amination reaction.

Another class of surfactants are semi-polar surfactants, such as amine oxides. Suitable amine oxides are selected from mono-C₈-C₂₀-, preferably -C₁₀-C₁₄-, N-alkyl or -alkenylamine oxides and propylene-1,3-diamine dioxides, in which the remaining N-positions are substituted by methyl, hydroxyethyl or hydroxypropyl groups.

Another class of surfactants are the amphoteric surfactants, such as the polyamine-based species.

Cationic surfactants may also be used in the detergent compositions herein and suitable quaternary ammonium surfactants are selected from mono-C8-C16, preferably -C10-C14, N-alkyl or alkenyl ammonium surfactants wherein the remaining N-positions are substituted by methyl, hydroxyethyl or hydroxypropyl groups.

Mixtures of surfactant types are preferred, especially anionic-nonionic and also anionic-nonionic-cationic mixtures. Very particularly preferred mixtures are described in GB-A-2,040,987 and EP-A-0,087,914.

Builder materials are typically present from 5 to 60% of the detergent compositions herein. The compositions herein are preferably free or approximately free of phosphate-containing builders (approximately free is defined herein as containing less than 1% of the total detergent builder system), and the builder system herein consists of water-soluble builders, water-insoluble builders, or mixtures thereof.

Water insoluble builders may be an inorganic ion exchange material, conventionally an inorganic hydrated aluminosilicate material, particularly a hydrated synthetic zeolite such as hydrated zeolite A, X, B or HS.

Preferred aluminosilicate ion exchange materials have the unit cell formula

Mz[(AlO2 )z(SiO2 )y]xH2 O

wherein M represents a calcium exchange cation, z and y are at least 6; the molar ratio of z to y is from 1.0 to 0.5 and x is at least 5, preferably from 7.5 to 276, more preferably from 10 to 264. The aluminosilicate materials are in hydrated form and are preferably crystalline with 10 to 28%, more preferably with 18 to 22% water.

The above aluminosilicate ion exchange materials can be further characterized by a particle size diameter of from 0.1 to 10 µm, preferably from 0.2 to 4 µm. The term "particle size diameter" herein represents the average particle size diameter of a given ion exchange material, which is determined by conventional analytical techniques, such as microscopic determination using a scanning electron microscope. The aluminosilicate ion exchange materials may ... The aluminosilicate ion exchange materials herein may be further characterized by their calcium ion exchange capacity, which is at least 200 mg equivalents CaCO3 water hardness/g aluminosilicate, calculated on an anhydrous basis, and which is generally in the range of from 300 mg eq./g to 352 mg eq./g. The aluminosilicate ion exchange materials herein may be further characterized by their calcium ion exchange rate, which is described in detail in GB-A-1,429,143.

Aluminosilicate ion exchange materials useful in the practice of this invention are commercially available and may be naturally occurring materials, but are preferably prepared synthetically. A process for preparing aluminosilicate ion exchange materials is discussed in US-A-3,985,669. Preferred synthetic crystalline aluminosilicate ion exchange materials useful herein are available under the designation zeolite A, zeolite B, zeolite X, zeolite HS, and mixtures thereof. In a particularly preferred embodiment, the crystalline aluminosilicate ion exchange material is zeolite A and has the formula

Na 12 [(AlO 2 ) 12 (SiO 2 ) 12 ]xH 2 O

where x ranges from 20 to 30 and is especially 27. Zeolite X of the formula

Na 86 [(AlO 2 ) 86 (SiO 2 ) 106 ] · 276 H 2 O

is just as suitable as zeolite HS of the formula Na₆[(AlO₂)₆(SiO₂)₆] 7.5 H₂O.

Another suitable water-soluble inorganic builder material is a layered silicate, e.g. SKS-6 (Hoechst). SKS-6 is a crystalline layered silicate, consisting of sodium silicate (Na₂Si₂O₅). The high Ca⁺⁺/Mg⁺⁺ binding capacity is mainly due to a cation exchange mechanism. In hot water the material becomes more soluble.

The water-soluble builder can be a monomeric or oligomeric carboxylate complexing agent.

Suitable carboxylates having one carboxy group include lactic acid, glycolic acid and ether derivatives thereof as disclosed in BE-A-831,368, BE-A-821,369 and BE-A-821,370. Polycarboxylates having two carboxy groups include the water-soluble salts of succinic acid, malonic acid, (ethylenedioxy)diacetic acid, maleic acid, diglycolic acid, tartaric acid, tartronic acid and fumaric acid, as well as the ether carboxylates described in DE-A-2,446,686, DE-A-2,446,687 and US-A-3,935,257 and the sulfinyl carboxylates described in BE-A-840,623 Polycarboxylates having three carboxy groups include in particular water-soluble citrates, aconitates and citraconates as well as succinate derivatives such as the carboxymethyloxysuccinates described in GB-A-1,379,241, lactoxysuccinates described in Dutch patent application 7205873 and the oxypolycarboxylate materials such as 2-oxa-1,1,3-propanetricarboxylates described in GB-A-1,387,447.

Polycarboxylates containing four carboxy groups include oxydisuccinates disclosed in GB-A-1,261,829, 1,1,2,2-ethanetetracarboxylates, 1,1,3,3-propanetetracarboxylates and 1,1,2,3-propanetetracarboxylates. Polycarboxylates containing sulfo substituents include the sulfosuccinate derivatives disclosed in GB-A-1,398,421 and GB-A-1,398,422 and in US-A-3,936,448 and the sulfonated pyrolyzed citrates described in GB-A-1,082,179, while polycarboxylates containing phosphono substituents are disclosed in GB-A-1,439,000.

Alicyclic and heterocyclic polycarboxylates include cyclopentane cis,cis, cis-tetracarboxylates, cyclopentadienide pentacarboxylates, 2,3,4,5-tetrahydrofuran cis,cis,cis-tetracarboxylates, 2,5-tetrahydrofuran cis-dicarboxylates, 2,2,5,5- tetrahydrofuran tetracarboxylates, 1,2,3,4,5,6-hexane hexacarboxylates and carboxymethyl derivatives of polyhydric alcohols such as sorbitol, mannitol and xylitol. Aromatic polycarboxylates include mellitic acid, pyromellitic acid and phthalic acid derivatives disclosed in GB-A-1,425,343.

Among the above polycarboxylates, hydroxycarboxylates with up to three carboxy groups per molecule, especially citrates, are preferred.

Preferred builder systems for use in the preferred granular detergent compositions herein include a mixture of a water-insoluble aluminosilicate builder, such as zeolite A, and a water-soluble carboxylate complexing agent, such as citric acid.

Other builder materials that may form part of the builder system include inorganic materials such as alkali metal carbonates, bicarbonates, silicates and organic phosphonates, aminopolyalkylene phosphonates and aminopolycarboxylates.

The detergent compositions or detergent additives herein may contain a further anti-resoiling or soil suspending agent to in addition to the poly(amino acid) compounds herein. Such anti-resoiling and soil suspending agents useful herein include cellulose derivatives such as methylcellulose, carboxymethylcellulose and hydroxycellulose, homo- or copolymeric polycarboxylic acids or their salts and polyamino compounds. Polymers of this type include the polyacrylates and maleic anhydride-acrylic acid copolymers disclosed in detail in EP-A-0,137,669, as well as copolymers of maleic anhydride with ethylene, methyl vinyl ether or methacrylic acid, wherein the maleic anhydride constitutes at least 20 mole percent of the copolymer. These materials are normally used in ranges of 0.025% to 5% by weight of the compositions herein. EP-A-311,342 discloses specific modified polyesters which function as soil repellents on polyester fabrics; these modified polyesters are also contemplated herein.

The cleaning compositions, in particular the detergent compositions, are preferably in granular form and most preferably in a "compact form", i.e. with a density above the density of conventional detergent compositions. The preferred density of the compositions herein ranges from 550 to 950 g/l, preferably from 650 to 850 g/l of composition, measured at 20°.

The present invention is illustrated in and by the following examples.

example 1

Three formulations containing sodium polyaspartate were prepared with the composition :

LAS 9.52 parts by weight

TAS 0.49

25E3 3.26

TAE11 1.11

Zeolite A 19.5

Citrate 6.56

Sodium polyaspartate 3.19

Silicate (2.0 ratio) 3.5

Carbonate 14.52

TAED 5.0

Perborate 16.0

DETPMP 0.38

MgSO4 0.40

Enzyme 1,4

CMC0.48

Brightener 0.24

Photobleaching 0.002

Foam suppressor 0.54

Fragrance 0.43

The first formulation contained the polyaspartate added directly by dry addition. The second formulation contained the polyaspartate added as an agglomerate with sodium zeolite, sodium carbonate, anionic surfactant and CMC. The third formulation contained the polyaspartate added as an agglomerate with sodium zeolite, anionic surfactant and CMC (i.e. without carbonate).

The agglomerates added to the second and third compositions each had the following components

Each of the three formulations was packaged in a standard detergent cardboard carton and left open to the atmosphere under stress storage conditions (90ºF (32.2ºC) and 80% relative humidity) for a period of 8 weeks. Samples of each formulation were taken at specific intervals during the storage period and analyzed by both quantitative and qualitative methods using the standard analytical technique of capillary zone electrophoresis (CZE) and also by a standard detergent formulation performance testing procedure.

CZE curves (electropherograms) were recorded from samples of each of the three formulations taken from the respective stored products at intervals of 2, 4, 6 and 8 weeks. A polyaspartate reference sample, which which was not subjected to storage was also analyzed by CZE. The electropherograms showed decomposition of the polyaspartate during the storage period in the cases of the first formulation (direct addition of polyaspartate) and the second formulation (addition in the form of carbonate-containing agglomerates).

From both the qualitative and quantitative analysis of the polyaspartate performance over the 8-week storage period, it was concluded that the polyaspartate decomposes when exposed to high alkalinity.

Example 2

Tests were conducted to determine which of the detergent ingredients were responsible for the degradation of the polyaspartate.

A series of open-lid plastic cups (500 mL capacity) were prepared, each containing sodium polyaspartate and one of the following components: (a) sodium zeolite, (b) sodium percarbonate plus TAED, (c) sodium perborate tetrahydrate plus TAED, (d) a proteolytic enzyme, and (e) sodium carbonate.

The amounts used in the cups were as follows (wt%).

All were dry mixes.

The cups were subjected to stress storage conditions (90ºF (32.2ºC); 80% relative humidity) with their lids open. The polyaspartate content in each case was quantitatively analyzed by CZE and the results showed that no significant degradation occurred in the case of composition (d) with the enzyme and only a small degree of degradation occurred in composition (a) with the zeolite (such minimal degradation being attributed to trace alkalinity in the zeolite material); however, there was significant degradation of the polyasparate in compositions (b) and (c) with a bleach and bleach activator, which also occurred in composition (e) with the carbonate.

Example 3

A series of compositions were prepared in the form of agglomerates, each containing four parts by weight of polysuccinimide and 0, 1, 2, 3, 4, 5 or 10 parts by weight of sodium carbonate. The agglomerates were added to the respective samples of a conventional laundry detergent matrix containing surfactant, builder, bleach, complexing agent, enzyme and minor ingredients such as perfume and colorant. The agglomerates were added in an amount typical for the addition of dispersant to laundry detergent compositions.

The resulting dispersant-containing compositions were maintained under stress storage conditions for an 8-week storage period. During this period, the samples were quantitatively analyzed using CZE.

The CZE curves showed that where the amount of carbonate was less than or equal to equimolar with respect to the monomeric units in the polysuccinimide, the latter was partially or completely converted to polyaspartate, but no significant decomposition of the latter occurred within the test period. (In the experiment in which carbonate was absent, no conversion of the polysuccinimide to polyaspartic acid occurred.) In contrast, where the amount of carbonate was above equimolar with respect to the monomeric units in the polysuccinimide, the latter was converted to polyaspartate, but this underwent significant decomposition; indeed, in the composition with an extremely high content (10 parts) of carbonate, complete decomposition of the polyaspartate occurred within 2 weeks.

Example 4

The following laundry detergent products can be prepared using polyaspartic acid, its sodium salt or polysuccinimide as a dispersant (amounts are in parts by weight).

Water and various things to balance things out.

It is, of course, to be understood that the present invention has been described above only by way of example and that modifications in detail can be made within the scope of the invention.

In the detergent composition, the abbreviated component names have the following meanings:

LAS: linear sodium C12 alkyl benzene sulfonate

TAS: Sodium tallow alcohol sulfate

TAEn: tallow alcohol, ethoxylated with n moles of ethylene oxide per mole alcohol

25E3: A primary C₁₂₋₁₅ alcohol condensed with an average of 3 moles of ethylene oxide

TAED: Tetraacetylethylenediamine

Silicate: Amorphous sodium silicate (SiO₂: Na₂O ratio follows normally)

Carbonate: Anhydrous sodium carbonate

CMC: sodium carboxymethylcellulose

Zeolite A: Hydrated sodium aluminosilicate of the formula Na₁₂(AlO₂SiO₂)₁₂·27 H₂O with a primary particle size in the range of 1 to 10 µm

Citrate: Trisodium citrate dihydrate

Photobleaching: tetrasulfonated zinc phthalocyanine

MA/AA: Maleic acid/acrylic acid 1:4 copolymer, average molecular weight approximately 80,000

Enzyme: mixed proteolytic and amylolytic enzymes, sold by Novo Industries AS

Brightener: Disodium 4,4'-bis(2-morpholino-4-anilino-s-triazin-6- ylamino)stilbene-2 : 2'-disulfonate

DETPMP: Diethylenetriaminepenta(methylenephosphonic acid), marketed by Monsanto under the trade name Dequest 2060

Mixed foam suppressors: 25% paraffin wax, melting point 50ºC, 17% hydrophobic silicon dioxide, 58% paraffin oil

Claims (15)

1. A detergent composition comprising a polyamino acid compound or a precursor thereof and a detergent surfactant, characterized in that the polyamino acid compound or the precursor thereof is coated or encapsulated with another material. 2. The composition of claim 1, wherein the polyamino acid compound or precursor thereof is coated with a coating comprising an organic acid compound, a polymeric film-forming material, or a mixture thereof. 3. A cleaning composition comprising a polyamino acid compound or a precursor thereof and a detergent surfactant, wherein the polyamino acid compound or the precursor thereof is in the form of a spray granulate with a nonionic surfactant. 4. A cleaning composition comprising a polyamino acid compound or a precursor thereof and a detergent surfactant, wherein the polyamino acid compound or the precursor thereof is in the form of an agglomerate with an alkaline or alkaline reacting compound. 5. The composition of claim 4, wherein the alkaline or alkaline-reacting compound is present in an amount which is equimolar or less with respect to the monomer units of the polyamino acid constituent or precursor thereof. 6. A cleaning composition according to claim 4 or 5, wherein the alkaline or alkaline reacting material is a salt or silicate. 7. Cleaning composition according to at least one of claims 1 to 6, containing a polyamino acid compound selected from polyaspartic acid and its salts, polyglutamic acid and its salts and mixtures of two or more of these. 8. Cleaning composition according to at least one of claims 1 to 7, containing no or substantially no bleach. 9. Builder component containing a polyamino acid compound or a precursor thereof which is coated or encapsulated with another material. 10. Builder component in the form of an agglomerate of a polyamino acid or a precursor thereof and an alkaline salt or silicate, preferably a carbonate or bicarbonate salt or in the form of an agglomerate of the polyamino acid with a non-ionic surfactant and/or zeolite. 11. The builder component of claim 10, wherein the alkaline or alkaline-reacting material is present in an amount sufficient to effect complete neutralization of the polyamino acid or the polyamino acid derived from its precursor without causing degradation thereof. 12. The component of claim 10, wherein the alkaline or alkaline-reacting material is present in an amount that is equimolar or less with respect to the monomeric units of the polyamino acid compound or precursor thereof. 13. Builder component in the form of an agglomerate according to claim 10, wherein the polyamino acid compound or the precursor thereof is agglomerated with a nonionic surfactant or zeolite. 14. A process for preparing a polyamino acid compound in the form of an agglomerate according to claims 10 to 12, comprising agglomerating the alkaline or alkaline reacting material with a compound which is converted to the polyamino acid compound under alkaline conditions, the agglomeration being effected in the presence of sufficient moisture to allow the conversion to the polyamino acid compound to proceed. 15. The method of claim 14, wherein the polyamino acid compound is polyaspartic acid or a salt thereof, and wherein the alkaline or alkaline-reacting material is agglomerated with polysuccinimide.