DE69230801T2 - METHOD FOR THE PRODUCTION OF FLUSH-ACTIVE FOAM-BRAKING PARTICLES - Google Patents

Abstract

The present invention provides rinse-active foam-control particles for inclusion in a detergent composition in powder form, consisting essentially of a soap of fatty acids of which at least 80% contain from 16 to 18 carbon atoms, the geometric mean particle size of the particles being inferior to 1 mm, preferably inferior to 0.4 mm. The present invention also encompasses a process for making said foam-control agents, as well as high sud and low sud executions of detergent compositions containing said foam-control particles.

Description

Technical area

The present invention relates to a process for the preparation of rinse-active foam control particles for inclusion in a detergent composition, i.e. foam control particles active primarily in the rinse cycle of a washing process.

background

It has become common practice in the detergent industry to include materials in detergent compositions designed to control the amount of foam generated during a washing process.

Although foam control during the wash cycle of a laundry process is important to avoid negative effects of the wash liquor on the fabrics, it is also known that foam control during the rinse cycle of a laundry process is desirable.

In fact, excessive foaming during the rinse cycle in a washing machine can cause excess foam and damage the machine, while in the context of hand washing, the advantage of reducing foaming during the rinse is to shorten this step.

Soaps and fatty acids have been used for such rinse-active foam control function, and they have usually been spray dried together with the rest of the detergent composition.

However, there is a need to reduce organic emissions during detergent production, especially during spray drying.

EP-A-0 432 449, published on 19 June 1991, provides a powdered detergent composition comprising a spray dried base powder with no or only a small percentage of soap and additional soap "post-added" to the base powder by dry mixing.

GB-A-1 204 123, published on 3 September 1970, discloses a process for mixing detergent powder containing surfactant with other granules comprising an organic extrudable solid. Such an organic extrudable solid is a sodium salt of a C₈ to C₂₂ fatty acid.

GB-A-0 486 819, published on 10 June 1938, discloses a process for manufacturing a soap powder by converting a partially dried soap into a plastic or viscous mass, breaking the soap mass into discrete particles and solidifying the particles.

The present invention provides a process for preparing rinse-active foam control particles for inclusion in a powdered detergent composition.

The rinsing-active foam regulating particles comprise a soap, essentially consisting of a fatty acid soap, which consists of at least 80% by weight of 16 to 18 carbon atoms, the geometric mean particle size of the particles being below 1 mm, preferably below 0.4 mm.

The process of the present invention comprises the steps of drying the fatty acid soap slurry to a moisture content below 9% by weight of the slurry, pressing into noodles, and grinding the noodles into a fine powder.

Detailed description of the invention The antifoam particles

The foam control particles produced by the process of the invention consist essentially of a fatty acid soap, at least 80% by weight of which contains 16-18 carbon atoms; preferred fatty acids are tallow or tallow/coconut mixtures with a weight ratio of tallow to coconut of not less than 70/30; particularly preferred is a 90/10 tallow/coconut mixture. Suitable cations which render the soap water-soluble and/or dispersible include sodium, potassium, ammonium, monoethanolammonium, diethanolammonium, triethanolammonium or tetramethylammonium. Sodium ions are preferred.

The particles of the invention have a particle size such that the geometric mean particle size, which is the median value of the cumulative weight distribution, should be below 1 mm and preferably below 0.4 mm.

The single particle size of a particle is the sum of the longest and the shortest dimension of the particle divided by two.

The cumulative weight distribution of the particles can be conveniently measured by sieving with an air vortex sieve.

Optional components

The particles herein optionally include a flowable agent such as amorphous silica in amounts not exceeding 5% by weight of the particle.

Manufacturing process for the antifoam particles of the invention

The process herein necessarily includes the steps of drying the fatty acid soap slurry to a low moisture content, i.e. a moisture content not above 9%, preferably not above 5%, by weight of the slurry, then pressing the slurry into noodles and gradually grinding the noodles into a fine powder having a particle size required herein.

Control of moisture content is a particularly critical feature of the process herein, since successful milling to the required particle size is impossible without meeting the claimed moisture content.

Drying of the soap slurry is preferably achieved under vacuum. Additional drying during the milling process may be appropriate and is achieved, for example, in an air classifier.

A typical method of measuring the moisture content in the soap slurry and/or noodles is a solvent distillation process using a Bidwell® apparatus.

Detergent composition

The foam control particles prepared by the process of the present invention are suitable for use in a powdered detergent composition comprising a surfactant and the foam control particles as described above. Addition of the particles herein to detergent compositions can be achieved, for example, by dry blending. The proportion of foam control particles typically ranges from 0.25 to 5% by weight of the composition, depending on the type of detergent composition employed.

Surfactant

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 given in U.S. Patent 3,664,961 issued to Norris on May 23, 1972.

Mixtures of anionic surfactants are particularly suitable herein, most 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 prepared from a C12-C18 fatty source, preferably from a C12-C18 fatty source. In each case the cation is an alkali metal, preferably sodium.

Preferred sulfate surfactants are alkyl sulfates having 12 to 18 carbon atoms in the alkyl radical, optionally in admixture 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 herein are tallow alkyl sulfate, coconut alkyl sulfate and C₁₄₋₁₅ alkyl sulfates. The cation in each case is again an alkali metal cation, preferably sodium.

One class of nonionic surfactants useful in the present invention are condensates of ethylene oxide with a hydrophobic moiety to provide a surfactant with an intermediate hydrophilic-lipophilic balance (HLB) in of the order of 8 to 17, preferably 9.5 to 13.5, most preferably 10 to 12.5. The hydrophobic (liphophilic) moiety may be aliphatic or aromatic in nature, and the length of the polyoxyethylene group condensable with any particular hydrophobic group may be readily adjusted to obtain a water-soluble component having the desired degree of balance between hydrophilic and hydrophobic elements.

Particularly preferred nonionic surfactants of this type are the C9- C15 primary alcohol ethoxylates containing 3-8 moles of ethylene oxide per mole of alcohol, in particular the C14-C15 primary alcohols containing 6-8 moles of ethylene oxide per mole of alcohol and the C12-C14 primary alcohols containing 3-5 moles of ethylene oxide per mole of alcohol.

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

RO(CnH₂nO)tZx

wherein Z is a unit derived from glucose; R is 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 including 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-B 0 070 077, 0 075 996 and 0 094 118. Also suitable as nonionic surfactants are polyhydroxy fatty acid amide surfactants of the formula

wherein R¹ is H, C₁₋₄-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 at least 3 hydroxyl groups directly bound 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 the 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 types.

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, most particularly anionic-nonionic and also anionic-nonionic-cationic mixtures. Particularly preferred mixtures are described in British Patent No. 2040987 and Published European Application No. 0 087 914. The detergent compositions may comprise 1-70% by weight of surfactant, but usually the surfactant is present in the compositions herein in an amount of from 1 to 30% by weight, more preferably from 10 to 25% by weight.

The detergent compositions herein preferably also contain a builder which can be selected from phosphates, aluminosilicate ion exchangers (zeolites) and water-soluble monomeric or oligomeric carboxylate complexing agents such as citrates, succinates, oxydisuccinates and also from a mixture of the above compounds.

Other suitable builder materials include alkali metal carbonates, bicarbonates and silicates, organic phosphonates, aminopolyalkylene phosphonates and aminopolycarboxylates, ethylenediaminetetraacetic acid and nitrilotriacetic acid. Other suitable water-soluble organic salts are the homo- or copolymeric polycarboxylic acids or salts thereof in which the polycarboxylic acid comprises at least two carboxyl radicals separated by not more than two carbon atoms. Polymers of this type are disclosed in GB-A-1,596,756. Examples of these salts are polyacrylates having a molecular weight of 2000-5000 and their copolymers with maleic anhydride, such copolymers having a molecular weight of 20,000 to 70,000, especially about 40,000.

Other ingredients typically forming part of a powdered detergent composition include filler salts such as sodium sulfates, bleaching agents such as sodium perborate and percarbonate, bleach activators, anti-resoiling agents such as carboxymethylcellulose, enzymes such as proteases, amylases, lipases and cellulases, brighteners, fabric softening clays, fragrances, dyes and pigments.

The detergent compositions herein may be of the "high sudsing" type, intended for use in hand washing or in upright washing machines. In such embodiments, the level of suds control particles is typically from 2 to 5% by weight.

The compositions according to the invention may also be of the "low foaming" type and are therefore suitable for use in washing machines of any type; in this latter category, the detergent compositions comprise "compact" versions in which the density is typically above 550 g/l of composition and the proportion of filler salt is typically below 5% by weight of the composition.

In such embodiments, the proportion of foam control particles typically ranges from 0.25% to 2%.

In the "low foaming" embodiment herein, a wash cycle active foam control agent is typically included in addition to the rinse active foam control agents of the invention. Such additional foam control agents The preferred emulsifying agents are silicones.

Examples

The following examples illustrate the invention and facilitate its understanding.

The abbreviations of the individual components have the following meaning:

LAS: Sodium salt of linear dodecylbenzenesulfonate

TAS: Sodium salt of tallow alcohol sulfate

Non-ionic: fatty alcohol (C₁₄-C₁₅) ethoxylated with approximately 7 moles of ethylene oxide

Copolymer AA/MA: Copolymer of acrylic acid and maleic acid

CMC: carboxymethyl cellulose

Na-Phosphonate: Sodium salt of ethylenediaminetetramethylenephosphonic acid

TAED: Tetraacetylethylenediamine

The following compositions were prepared.

Example II ("High-foaming" embodiment)

LAS20%

Sodium tripolyphosphate 23%

Sodium silicate 6%

CMC0.15%

Sodium sulfate 34%

Sodium phosphonate 0.1%

Sodium carbonate 5%

Copolymer AA/MA 2.5%

Sodium soap particles* 3%

Enzyme, brightener, fragrance and

Minor ingredients per 100

Density 360 g/l

*prepared as described above and dry mixed with the rest of the composition.

Example II ("Low-foaming" embodiment, in compact form)

LAS8%

TAS2%

Non-ionic 6%

Sodium carbonate 14%

Sodium citrate 6%

Zeolite 20%

Sodium silicate 3%

CMC0.5%

Sodium sulfate 3.5%

Sodium phosphonate 0.4%

Sodium perborate monohydrate 16%

Sodium soap particles* 1%

Silicone 0.5%

Sodium salt of copolymer AA/MA 4%

TAED 5%

Enzyme, fragrance, brightener and minor ingredients per 100

Density 700 g/l

*prepared as described above and dry mixed with the rest of the composition.

Claims (5)

1. A process for the preparation of a foam control agent, the foam control agent comprising rinse-active foam control particles for inclusion in a powdered detergent composition, the rinse-active foam control particles consisting essentially of a soap made from fatty acids, at least 80% by weight of the fatty acid soap containing 16 to 18 carbon atoms, the geometric mean particle size of the particles, which is the median value of the cumulative weight distribution, being below 1 mm, characterized in that a fatty acid soap slurry is dried to a moisture content below 9% by weight of the slurry, pressed into noodles and the noodles are ground to a fine powder. 2. The method of claim 1, wherein the foam control particles have a geometric mean particle size below 0.4 mm. 3. A method according to claim 1, wherein the soap is selected from fatty acids from tallow soap and tallow/coconut soap with a weight ratio of tallow to coconut of not less than 70/30. 4. The process of claim 1, wherein the soap slurry is dried to a moisture content not exceeding 5% by weight of the slurry. 5. The process of claim 1, wherein the soap slurry is vacuum dried.