DE3688821T2 - Granulated detergent with solubility. - Google Patents

Description

Technical area

The present invention relates to granulated detergent compositions containing a specific mixture of an alkylbenzene sulfonate surfactant, alkyl sulfate surfactant, an alkali metal silicate and sodium sulfate. The compositions are prepared by drying, preferably by spray drying, an aqueous slurry comprising the above components. Although the spray dried components forming the base granules of the compositions preferably also contain detergent builder materials, these are free or substantially free of anhydrous Form 1 pyrophosphate or tripolyphosphate builder.

Mixtures of alkylbenzenesulfonate and alkylsulfate surfactants are desirable to achieve optimal washing results. However, such mixtures tend to gel when in contact with water. This can lead to poor solubility of granules with high contents of alkylbenzenesulfonate and alkylsulfate surfactants, especially when such granules are incorporated into dense detergent compositions.

It has now been found that highly soluble granulated detergent compositions containing high levels of alkylbenzene sulfonate and alkyl sulfate surfactants can be obtained by drying an aqueous slurry containing the surfactants, silicate in a weight ratio of surfactant to silicate within the range of 1.5:1 to 6:1, sodium sulfate and substantially no pyrophosphate or tripolyphosphate anhydrous Form I detergent builder material. In preferred compositions, these soluble detergent granules are blended or agglomerated with builders or other optional detergent ingredients. Particularly preferred compositions are obtained by mixing the soluble granules with builders, compacting the mixture at relatively low pressures (for example 137.9 kPa to 1379 kPa) and optionally mixing in additional builders and other ingredients to provide finished granulated detergent compositions.

State of the art

U.S. Patent 4,028,283, Murata et al., issued June 7, 1977, describes granulated detergents containing caking surfactants and an anti-caking agent formed by reacting polyethylene glycol with an acid anhydride. The compositions may also contain 0-20% of other surfactants such as alkylbenzene sulfonates. Examples include spray dried detergents containing mixtures of alkylbenzene sulfonate and alkyl ethoxysulfate surfactants, silicate and builders.

U.S. Patent 4,141,841, McDonald, issued February 27, 1979, describes granulated detergents containing particulate antistatic/softening additives. In Example 8, the particles are mixed with spray dried base granules containing about 27% of a mixture of alkylbenzene sulfonate and alkyl ethoxysulfate surfactants, 18% silicate and about 22% sodium tripolyphosphate.

EP-A-0 084 657 describes physically stable, high foaming, spray dried granulated detergent compositions comprising 35-50% C₁₀-C₁₄ alkylbenzenesulfonates, 0-15% C₁₀-C₂₀ alkylsulfates, 5-20% sodium silicate, 0-10% sodium sulfate, 5-25% sodium tripolyphosphate and 5-25% sodium aluminosilicate zeolite.

AU-A-61106 describes mixtures of linear C₁₀-C₁₅ alkylbenzenesulfonates and C₁₄-C₁₈ alkyl sulfates in a tripolysulfate builder, silicate and sulfate-containing spray dried detergent composition with enhanced cleaning properties.

Japanese OPI 106509, published August 21, 1979, describes spray dried granulated detergents containing 15-40% surfactant, 5-20% silicate and not more than 12% phosphate. The compositions are stated to have good physical properties and to cause reduced deposition of insolubles on fabrics.

The Japanese OPI 72998 and 72999, published on April 25, 1985, describe dense granulated detergents formed by mixing under high shear alkylbenzene sulfuric acid and alkyl sulfuric acid with sodium carbonate and water to effect neutralization, adding other ingredients such as builders, and then crushing and granulating the mixture.

Summary of the invention

The invention relates to a granulated detergent composition which includes base granules prepared by drying an aqueous slurry, wherein the base granules contain, by weight:

(a) 30 to 60% of a mixture of a C₁₁-C₁₃ alkylbenzenesulfonate surfactant and a C₁₂-C₁₆ alkyl sulfate surfactant in a weight ratio of sulfonate surfactant to sulfate surfactant of 4:1 to 1:4;

(b) an alkali metal silicate having a molar ratio of SiO2 to alkali metal oxide of 1.0 to 3.2;

wherein the weight ratio of (a) to (b) is 1.5:1 to 6:1;

(c) 10 to 60% sodium sulfate; and

(d) 0 to 60% of a detergent builder material other than a pyrophosphate or tripolyphosphate of anhydrous form I

wherein the base granules contain less than 5% by weight of an anhydrous Form I pyrophosphate or tripolyphosphate detergent builder material;

the composition having an average particle size of 20 to 1500 µm, the composition being obtained by mixing the base granules with 0 to 300%, based on the weight of the base granules, of a detergent builder material, compacting the base granules or the base granule-builder material mixture at a pressure of 137.9 to 1379 kPa to form a compacted mass, thereafter granulating the compacted mass and then with a further 0 to 300%, based on the weight of the base granules, a detergent builder material, the composition having a bulk density of 0.55 to 1.2 g/cm³.

The basic granulate composition is the subject of the European patent application with the publication number 0 219 314, which also goes back to the applicant.

Detailed description of the invention

The granulated detergent compositions of the invention comprise base granules containing from 30% to 60%, more preferably from 40% to 50%, by weight, of a mixture of a C₁₁-C₁₃ alkylbenzenesulfonate surfactant and a C₁₂-C₁₆ alkyl sulfate surfactant in a weight ratio of sulfonate surfactant to sulfate surfactant of from 4:1 to 1:4, preferably from 3:1 to 1:3, more preferably from 2:1 to 1:2.

Sulfonate surfactants useful herein are the water-soluble salts, particularly the alkali metal, ammonium and alkanolammonium (e.g. monoethanolammonium or triethanolammonium) salts of alkylbenzenesulfonates in which the alkyl group contains 11 to 13 carbon atoms of a straight-chain or branched-chain configuration, for example those of the type described in U.S. Patents 2,220,099 and 2,477,383.

Preferred are linear, straight-chain alkylbenzenesulfonates in which the average number of carbon atoms in the alkyl group is 12 to 13.

Suitable alkyl sulfate surfactants are the water-soluble salts, especially the alkali metal, ammonium and alkanolammonium (for example monoethanolammonium or triethanolammonium) salts of C₁₂-C₁₆ linear or branched alkyl sulfates. Preferred are those which contain a C₁₂-C₁₅, especially C₁₄-C₁₅ linear alkyl group.

The compositions of the invention may also contain small amounts (generally less than about 30%, but preferably less than 15% by weight of the above sulfonate and sulfate surfactants) of other detergent surfactants known in the art. These may include anionic, nonionic, cationic, ampholytic and zwitterionic surfactants such as those described in U.S. Patent 3,919,678, Laughlin et al., issued December 30, 1975.

The compositions of the invention also contain an alkali metal silicate having a molar ratio of SiO2 to alkali metal oxide of 1.0 to 3.2, preferably 1.6 to 2.4. Sodium silicate, particularly one having a molar ratio of 1.6 to 2.2, is preferred.

The alkali metal silicates may be obtained in either liquid or granular form. Silicate solutions or slurries may be conveniently used to avoid having to dissolve the dried form in the aqueous slurry (e.g. homogenizer) of the components mentioned herein.

Furthermore, the weight ratio of the alkylbenzenesulfonate plus alkyl sulfate surfactants to the alkali metal silicate herein is 1.5:1 to 6:1, preferably 2:1 to 4:1, more preferably 2.5:1 to 3.5:1.

The present compositions further contain from 10 to 60%, preferably from 20 to 50%, by weight of sodium sulfate. Sodium sulfate is usually formed during the sulfation/sulfonation and neutralization steps in the preparation of the alkyl benzosulfonate and alkyl sulfate surfactants used herein.

The present compositions are prepared by drying an aqueous slurry comprising the components. The slurry generally contains from 25% to 70%, preferably from 40% to 60%, water, whereas the dried granules initially contain from 1% to 10%, preferably from 1% to 3%, water.

The drying process can be carried out by any suitable means, such as by using spray drying towers, both countercurrent and parallel current, fluidized beds, a flash dryer, or an industrial microwave or oven dryer. These are more fully described in U.S. Patent 4,019,998, Benson et al., issued April 26, 1977 (particularly column 14, cell 19 through column 15, line 9).

The present granulated detergents are very soluble in wash water, even though they contain high levels of alkylbenzene sulfonate and alkyl sulfate surfactants. Good solubility is obtained when the weight ratio of total sulfonate plus sulfate surfactant to silicate is within the above-mentioned range of 1.5:1 to 6:1. Without being limited to theory, it is believed that this relatively high silicate content provides structure and helps to maintain the cohesion of the high surfactant granules and that this minimizes gelling when the surfactants come into contact with the wash water. However, if the silicate content becomes too high (for example, a 1:1 surfactant to silicate ratio), the overall solubility may suffer due to the formation of insoluble silicate moieties. On the other hand, granules with a surfactant to silicate ratio of, for example, 8:1 have an inadequate structure and tend to be too mushy at these high surfactant contents.

To achieve good solubility, the base granule components of the composition of the invention are free or substantially free of pyrophosphate or tripolyphosphate detergent builder of anhydrous form 1. For the purposes of the invention, "substantially free" means that they contain less than 5%, preferably less than 3%, by weight of such builder materials.

The composition may contain up to 60%, preferably 1% to 45%, by weight of other builders, including any of those described in U.S. Patent 3,925,262, Laughlin et al., issued December 9, 1975. Builders are generally selected from various water-soluble alkali metal, ammonium or substituted ammonium phosphonates, polyphosphonates, carbonates, borates, polyhydroxysulfonates, polyacetates, carboxylates and polycarboxylates. Preferred are the alkali metal, particularly sodium salts of the above.

Examples of polyphosphonate builders are the sodium and potassium salts of ethylenediphosphonic acid, the sodium and potassium salts of ethane-1-hydroxy- 1,1-diphosphonic acid and the sodium and potassium salts of ethane-1,1,2-triphosphonic acid. Other phosphorus builder compounds are described in U.S. Patent Nos. 3,159,581; 3,213,030; 3,422,021; 3,422,1137; 3,400,176 and 3,400,148.

Examples of phosphorus-free inorganic builders are sodium and potassium carbonate, bicarbonate, sesquicarbonate and tetraborate decahydrate.

Water-soluble, phosphorus-free organic builders suitable herein include the various alkali metal, ammonium and substituted ammonium polyacetates, carboxylates, polycarboxylates and polyhydroxysulfonates. Examples of the polyacetate and polycarboxylate builders are the sodium, potassium, lithium, ammonium and substituted ammonium salts of ethylenediaminetetraacetic acid, nitrilotriacetic acid, oxydisuccinic acid, mellitic acid, benzenepolycarboxylic acids and citric acid.

Polymeric polycarboxylate builders are also described in U.S. Patent 3,308,067, Diehl, issued March 7, 1967. Such materials include the water-soluble salts of homo- and copolymers of aliphatic carboxylic acids, such as maleic acid, itaconic acid, mesaconic acid, fumaric acid, aconitic acid, citraconic acid and methylenemalonic acid.

Other builders suitable herein are sodium and potassium carboxymethyloxymalonate, carboxymethyloxysuccinate, cis-cyclohexanehexacarboxylate, cis-cyclopentanetetracarboxylate, phloroglucinoltrisulfonate and the copolymers of maleic anhydride with vinyl methyl ether or ethylene.

Other suitable polycarboxylates are the polyacetal carboxylates described in U.S. Patent 4,144,226, issued March 13, 1979 to Crutchfield et al. and U.S. Patent 4,246,495, issued March 27, 1979 to Crutchfield et al.

These polyacetal carboxylates can be prepared by bringing together under polymerization conditions an ester of glyoxylic acid and a polymerization initiator. The resulting polyacetal carboxylate ester is then attached to chemically stable end groups to stabilize the polyacetal carboxylate against rapid depolymerization in alkaline solution and converted to the corresponding salt.

The above granulated detergent compositions can be used as ready-made detergent compositions or as detergent additive compositions. However, they are preferably used as (and hereinafter referred to as) detergent base granules, which are then with builder material and with other optional ingredients to provide finished detergent compositions which exhibit good solubility. Such finished compositions may contain, by weight, from 5% to 50%, preferably from 10% to 40%, more preferably from 12% to 25% of the alkylbenzene sulfonate and alkyl sulfate surfactants mentioned herein and from 5% to 95%, preferably from 10% to 85%, more preferably from 15% to 75% of the detergent builder material. When admixed, the builders mentioned herein should have the same particle size as the remainder of the composition as described herein.

The detergency builder materials which are incorporated may comprise any of those described above and may also include phosphate materials such as sodium and potassium tripolyphosphate (Form II or hydrated Form I), polymeric metaphosphate having a degree of polymerization of 6 to 21 and orthophosphate. However, for best solubility, the amount of pyrophosphate and anhydrous Form I tripolyphosphate should be minimal, i.e. the finished compositions preferably contain 0% to 20%, preferably 0% to 10% of such material or mixtures thereof.

The compositions may also contain small amounts, generally less than 30% by weight, preferably less than 20% by weight, of other ingredients usually present in detergent compositions. These include auxiliary detergent surfactants, color granules, bleaches and bleach activators, foam improvers or foam regulators, anti-tarnish and anti-corrosive agents, soil-carrying agents, soil-repellent agents, colorants, fillers, optical brighteners, germicides, pH regulators, non-builders, alkalinity sources, enzymes, enzyme stabilizing agents and perfumes.

Agglomeration can be achieved by stirring in the presence of a suitable binder (for example in a fluidized bed, tumbler mixer or a rotating roller or vat) or by mechanical mixing under pressure (for example extruding, pressing, milling or rolling, compacting or pelletizing). Final sizing can be achieved by milling and sieving.

In the present invention, the detergent base granules are mixed with 0% to 300%, preferably 25% to 200%, more preferably 50% to 150%, based on the weight of the base granules, of a detergent builder material as described above. The resulting mixture is then preferably compacted at a relatively low pressure of 137.9 to 1379, preferably 275.8 to 1034, more preferably 344.8 to 689.4 kilo Pascals (kPa).

The composition is then preferably mixed with a further 0% to 300%, preferably 25% to 200%, more preferably 50% to 150%, based on the weight of the base granules, of a detergent builder material. The above levels and types of builder material and the compaction pressure are preferably chosen so that the final detergent composition has a bulk density of 0.55 to 1.2, preferably 0.65 to 1.1, more preferably 0.70 to 0.9 g/cm3 and an average particle size of 20 to 1500 µm, preferably 50 to 1200 µm, more preferably 100 to 800 µm.

The above compaction step is preferably carried out using equipment which applies a relatively uniform compaction pressure, for example using compaction rollers with smooth (i.e., non-corrugated) surfaces. After compaction, the composition is preferably granulated and sieved to provide an average particle diameter equal to that desired for the final composition.

The following non-limiting examples illustrate the detergent compositions of the invention.

All percentages, parts and ratios are by weight, unless otherwise stated.

Example I

The following granulated detergent composition was prepared. Base Granules Weight % Grams Final Composition per Application Sodium C₁₃ Linear Alkylbenzenesulfonate Sodium C₁₄₋₁₅ Alkyl Sulfate Sodium Silicate (Ratio 1.6) Sodium Sulfate Polyethylene Glycol (MW 8000) Sodium Polyacrylate (MW 4500) C₁₂₋₁₅ Alcohol Polyethoxylate (6) Sodium Diethylenetriamine Pentaacetate Moisture

Premix

Basic granules 23,122

Sodium tripolyphosphate hexahydrate (powdered) 20,576

43,698

Admixture

Premix 43,698

Sodium tripolyphosphate hexahydrate (granulated) 19,429

Dye 0.003

Brightener 0.613

Foam regulator prill comprising dimethylsilicone, silicon dioxide, sodium tripolyphosphate and polyethylene glycol (molecular weight = 8000) 1.703

Proteases 2,044

Sodium carbonate 4,000

71,490

Spray application

Admixture 71,490

Mineral oil 0.710

72,200

The base granules were prepared by spray drying an aqueous homogenizer mixture of the components on a 305 cm tower using a homogenizer temperature of 93ºC, a 3-1/2 die to produce fine granules, and silicone deaerators. If the base granules contained more than 2% moisture, a second drying step was performed on a continuous fluid bed to reduce the moisture to 2%.

The base granules were then mixed with powdered STP hexahydrate to form a premix. The premix was compacted at 344.8 kPa roller pressure on a 10 cm by 25 cm Chilsonator and sieved to select a particle size cut-off of -14 (1168 µm)/+65 (208 µm) (Tyler mesh). Oversized particles were collected and granulated on a Fitzmill using a 1168 µm screen and low rpm. The resulting product was sieved to select a particle size cut-off of -20 (833 µm)/+48 (205 µm). Both materials were dedusted by blowing fine particles in a fluid bed dryer using ambient air.

The admixture was prepared in a drum mixer at 181.5 kg per batch. Carbonate, granulated STP (with dye sprayed on), brightener, enzymes and foam control prills were mixed with the densified mainstream product cut and the regranulated screen residue. The ratio of mainstream product cut to screen residue was 7 to 1. Mineral oil was sprayed onto the final admixture in 13.6 to 18.1 kg batches at a 1% level using a Forberg mixer.

The composition of Example 1 is preferably incorporated into a laminated laundry product formed from two layers of water-insoluble fabrics, at least one of which is water-permeable, which are laminated together. At least one of the layers has cup-shaped depressions surrounded by rims, the other layer is secured to the first layer at the edges to physically separate the cups from each other. In one embodiment, the laminate is formed with layers of tissue paper as described by Trokhan in U.S. Patent 4,529,480, issued July 16, 1985.

The fabric had good air permeability as set forth in U.S. Patent 4,170,565, Flesher et al., published October 9, 1979.

There are 12 cups each having a capacity of 20 cc, with at least 8 of the cups filled with about 9 mg (11 cc) of the detergent composition and the other cups filled with at least one detergent adjuvant. Other materials which can be used to form suitable laminates and methods of forming suitable laminates are described in Bahrani U.S. Patent No. 4,571,924 and European Patent Application Publication No. 0 184 261.

When the composition of Example 1 is incorporated into this laminated laundry product, it exhibits excellent solubility.

Example II

The following granulated detergent composition can be prepared and used according to Example I. Base Granules Weight % Grams Final Composition per Application Sodium C₁₃ linear alkylbenzenesulfonate Sodium C₁₄₋₁₅ alkyl sulfate Sodium silicate (ratio 1.6) Sodium sulfate Polyethylene glycol (molecular weight 8000) Sodium polyacrylate (molecular weight 4500) C₁₂₋₁₃ alcohol polyethoxylate (6) Sodium citrate unreacted moisture

Premix

Basic granules 43.23

Sodium aluminosilicate (hydrated zeolite A, average diameter 3 µm) 14.90

Sodium carbonate 3.00

61.13

Admixture

Premix 61.13

Brightener 0.53

Foam regulator prill comprising dimethylsilicone, silicon dioxide, sodium tripolyphosphate and polyethylene glycol (molecular weight = 8000) 0.91

Proteases 1.00

63.57

Claims (10)

1. A granulated detergent composition which includes base granules prepared by drying an aqueous slurry, the base granules containing, by weight: (a) 30 to 60% of a mixture of a C11-C13 alkylbenzenesulfonate surfactant and a C12-C16 alkyl sulfate surfactant in a weight ratio of sulfonate surfactant to sulfate surfactant of 4:1 to 1:4; (b) an alkali metal silicate having a molar ratio of SiO2 to alkali metal oxide of 1.0 to 3.2; wherein the weight ratio of (a) to (b) is 1.5:1 to 6:1; (c) 10 to 60% sodium sulfate; and (d) 0 to 60% of a detergent builder material other than a pyrophosphate or tripolyphosphate of anhydrous form I wherein the base granules contain less than 5% by weight of an anhydrous Form I pyrophosphate or tripolyphosphate detergent builder material; the composition having an average particle size of 20 to 1500 µm, the composition being obtained by mixing the base granules with 0 to 300%, based on the weight of the base granules, of a detergent builder material, compacting the base granules or the base granule-builder material mixture at a pressure of 137.9 to 1379 kPa to form a compacted mass, thereafter granulating the compacted mass and then mixing it with a further 0 to 300%, based on the weight of the base granules, of a detergent builder material, the composition having a bulk density of 0.55 to 1.2 g/cm³. 2. A composition according to claim 1, wherein the base granules comprise 35 to 60 wt% of the sulfonate and sulfate surfactants in a weight ratio of sulfonate surfactant to sulfate surfactant of 2:1 to 1:2. 3. Composition according to claim 1 and/or 2, wherein the sulfonate surfactant is a sodium C₁₂-C₁₃ linear alkylbenzenesulfonate and the sulfate surfactant is a sodium C₁₄-C₁₅ linear alkyl sulfate. 4. Composition according to at least one of claims 1 to 3, wherein the weight ratio of (a) to (b) is 2.0:1 to 4.0:1. 5. A composition according to any one of claims 1 to 4, wherein the uncompacted base granules are mixed with 50 to 150%, based on the weight of the base granules, of a detergent builder material. 6. A composition according to any one of claims 1 to 5, wherein the detergency builder material mixed with the base granules comprises sodium tripolyphosphate hexahydrate. 7. Composition according to at least one of claims 1 to 6, wherein the uncompacted base granule-builder material mixture is compacted at a pressure of 275.8 to 1034 kPa, preferably of 344.8 to 689.4 kPa. 8. A composition according to claim 7, wherein the compacted mixture is mixed with further detergent builder material in an amount of 50 to 150% by weight of the base granules. 9. Composition according to at least one of claims 1 to 8 with a bulk density of 0.70 to 0.9 g/cm³. 10. A laminated laundry product comprising two layers of water-insoluble fabric, wherein: (1) at least one layer is permeable to water; (2) at least one layer defines more than one cup, each cup being surrounded by an edge of that layer; (3) the second layer is joined to the first layer at least at the edges of the cups to physically separate the cups so that the contents of the cups remain in position; and wherein more than one cup contains a granulated detergent composition according to any one of claims 1 to 9.