DE69227311T2 - Detergent compositions - Google Patents

Abstract

A high active detergent paste composition which is suitable for making detergent granules which have an excellent white appearance making them suitable for use in consumer products. The paste compositions comprise a dye or optical brightener.

Description

FIELD OF INVENTION

There is currently a trend towards compact detergents, offering consumers a product that is more convenient to carry and store, while also reducing the weight of the packaging material used. To obtain these compact detergents, high-density, high-efficiency granules/agglomerates must be produced.

One problem associated with such highly active particles is discoloration of the organic surfactant material. Such discoloration is highly undesirable in the finished detergent product and can result in detergent granules made from a paste of anionic detergent salts having a yellow color which is unacceptable to the consumer and therefore not commercially desirable. This problem is particularly acute with granules containing high organic surfactant activity.

One way of producing high-potency detergent granules is to agglomerate high-potency pastes consisting of salts of anionic surfactants with detergent powders. Such pastes have previously been rarely used in the detergent industry for a number of reasons, including the practical difficulties of handling high-viscosity pastes and the need to maintain high temperatures to prevent solidification of the material and the problems associated with discoloration.

From a consumer acceptance point of view, there is a need to produce highly effective detergent granules that have a white or nearly white appearance. According to Herman de Groot, W. "Sulphonation Technology in the Detergent Industry", Kluwer Academic Publishers, 1991, a conventional approach to improving color is to bleach dark organic compounds, particularly anionic surfactants such as linear alkylbenzene sulfonate (LAS) or methyl esters sulfonate (MES). Bleaching is achieved by an agent which breaks the conjugated carbon double bonds either by reaction with one of the conjugated double bonds or by oxidation and/or reduction of the chromophore. There are a variety of bleaching agents potentially available for this purpose, but only sodium hypochlorite and hydrogen peroxide are of commercial importance. Sodium hypochlorite is a more convenient and effective bleaching agent than hydrogen peroxide. However, chlorine-based bleach may be undesirable because it may form sensitive substances during processing of some starting materials. Hydrogen peroxide may be used as an alternative, but it is less cost effective and may present difficulties in process control due to excessive foaming caused by the release of oxygen during bleaching.

GB-A-1 369 269, published on 2 October 1994, describes a process for dry neutralisation in the manufacture of detergent granules. It is stated that various difficulties arise, including local discolouration of the organic detergent. However, no solutions are specifically given for this problem.

GB-A-2 221 695, published on 14 February 1990, also describes a dry neutralisation process. It is stated that various additives can be added together with the neutralising agent, but no advantages are suggested for the addition of brighteners or colourants, apart from it being a convenient way of processing many additives.

GB-A-2 166 452, published on 8 May 1986, describes a process route which involves dispersing organic materials with particles of an inorganic component to produce solid pellets which can subsequently be granulated. A wide range of detergent ingredients are suggested which can be added during neutralisation, including agents for bluing, fluorescent dyes and pigments. Once again, however, there is no suggestion of any particular advantage to be gained by the selection of these ingredients.

In EP-A-327 963, published on 16 August 1989, a process of previously neutralising the surfactant acids in a slurry, spray drying the slurry to form a powder and compacting said powder is described. The brighteners may be incorporated in the slurry as a convenient way of incorporating them into the final composition, but there is no suggestion that this would be beneficial to the colour of the compacted granules.

EP-A-0 508 543, published on 14 October 1992, EP-A-0 510 746, published on 28 October 1992, and EP-A-0 555 622, published on 18 August 1993, are prior art under Article 54(3) EPC. These applications describe detergent compositions and processes for preparing such compositions from high-performance detergent pastes. The addition of an optical brightener to the final detergent composition is described, but there is no mention of the use of dyes or optical brightener in the high-performance detergent pastes to prevent discolouration.

These new processes, based on highly effective detergent pastes, allow the production of granules that have a higher surfactant activity than before, which can lead to the discoloration problems caused by starting materials in the form of hot surfactant pastes.

It is an object of the present invention to provide a composition of a highly effective paste of detergent salts which comprises special ingredients which impart a very acceptable white appearance to the finished detergent granules.

It is a further object of the present invention to provide a process for producing a concentrated detergent powder having high efficacy, high bulk density and a consumer acceptable color.

SUMMARY OF THE INVENTION

The invention relates to a process for producing a highly effective granular detergent which comprises the steps of dispersing an organic detergent component with particles of an inorganic component in the presence of a dye or an optical brightener, comprising the steps

(i) preparing a high performance paste containing at least 40 wt% of anionic surfactant salts, by neutralizing the corresponding acids, which paste has a viscosity of at least 10 Pa·s, measured at a temperature of 70°C and a shear rate of 25 s⊃min;1;

(ii) granulating said high potency paste to form agglomerates in a high shear mixer/granulator with an effective amount of detergent powders;

wherein the dye or the brightener or a mixture thereof is either added in step (i) of the process to a circulating reactor in which the anionic detergent acids are neutralized to form their salts, or

wherein the colorant or brightener is added in liquid form by premixing with the high-performance detergent paste in a batch mixing tank or continuously in an extruder, or

wherein the colorant or brightener in liquid form is pumped or sprayed into the high shear mixer/granulator in step (ii) of the process either as an aqueous solution or as a premix with a carrier.

The invention further relates to a highly effective detergent paste composition which contains at least 40% by weight of Composition of salts of anionic surfactants, which composition has a viscosity of at least 10 Pa·s measured at a temperature of 70°C and a shear rate of 25 s⁻¹, which further comprises a dye or an optical brightener or a mixture thereof.

DETAILED DESCRIPTION OF THE INVENTION

It has been found that the incorporation of certain dyes and optical brighteners into granules produced by an agglomeration process can impart to the fresh detergent granules very good coloring and color properties which are maintained or even improved during storage.

The dye or optical brightener is added to the composition in liquid form either before or during the agglomeration process. A preferred embodiment of this invention is to use either an aqueous solution or an organic carrier medium. In the most preferred embodiment, the organic carrier is a nonionic surfactant or polyethylene glycol.

Production of highly effective detergent granules

The granules of the present invention are prepared by mixing a high-potency paste comprising the salts of anionic surfactants with detergent powders in a high-shear mixer (agglomerator). The action of the mixer is first to fluidize the powder and then to rapidly disperse the surfactant paste in this fluidized powder. The resulting mixture consists at all times of essentially discrete particles. It is not allowed to form a dough which would cause blockage of the high-shear mixer. Inside the mixer, a process of mixing a fine dispersion and granulation takes place under the influence of cutting and mixing tools mounted on a shaft. Suitable paste compositions and processes are described in more detail hereinafter. The resulting particles have high interfacial activity and high bulk density, but still have good flow and non-packing properties. Preferably, the interfacial activity is more than 40% by weight of the particles and the bulk density is at least 600 g/l.

The dye or optical brightener in liquid form may either be premixed with the high-efficiency detergent paste by means of a batch mixing tank or added continuously to an extruder or neutralization loop, or it may be sprayed or pumped directly into the high shear mixer where it is dispersed in the particles formed therein. In a particularly preferred process, the dye or optical brightener is pumped directly into the neutralization loop where the acid forms of the surfactant are neutralized.

Suitable dyes and optical brighteners

Suitable dyes and optical brighteners for the present invention are those which emit light in the violet or blue region of the spectrum. For the present invention, it is preferred that the light emitted by these dyes be predominantly (at least 70%) in the visible light region below 500 nm wavelength. Examples of useful dyes include Levanyl Violet. BNZ (trade name) and Special Fast Blue G FW Ground (trade name), both of which are supplied by Bayer AG.

Preferred optical brighteners are among the sodium salts of:

4,4'-bis-(2-diethanolamino-4-anilino-s-triazine-6-ylamino)stilbene-2:2'-disulfonate,

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

4,4'-Bis-(2,4-dianilino-s-triazine-6-ylamino)stilbene-2:2'-disulfonate,

4',4"-Bis-(2,4-dianilino-s-triazine-6-ylamino)stilbene-2-sulfonate,

4,4'-Bis-(2-anilino-4-(N-methyl-N-2-hydroxyethylamino)-s-triazine-6-ylamino)stilbene-2,2'-disulfonate,

4,4'-bis(4-phenyl-2,1,3-triazol-2-yl)stilbene-2,2'-disulfonate,

4,4'-Bis-(2-anilino-4-(1-methyl-2-hydroxyethylamino)-s-triazine-6-ylamino)stilbene-2,2'-disulfonate,

4,4-bis-(2-sulfostyryl)biphenyl or

4,4-Bis-(4-chloro-3-sulfostyryl)biphenyl

selected.

Other optical brighteners which are also preferred for use in the present invention include the derivatives of bisbenzoxazolyl and 1,3-diphenyl-2-pyrazoline.

The amounts of dye used in the detergent paste are usually less than 20 ppm, preferably from 0.1 to 20 ppm. (These amounts are given as parts per million of pure dye, although such dyes are usually supplied as solutions.)

The amount of optical brightener in the surfactant paste is generally less than 5% and preferably less than 2%. The amount of optical brightener in the granular detergent component or composition is typically less than 2%, preferably less than 1%.

The pastes

One or several aqueous pastes of the salts of inorganic surfactants are preferred for use in the present invention, particularly the sodium salt of the anionic surfactant. In a preferred embodiment, the anionic surfactant is preferably as concentrated as possible (i.e., with the lowest possible moisture content that still allows the paste to flow in a liquid-like manner) so that it can be pumped at temperatures at which it remains stable. Although the granulation of various pure or mixed surfactants is known, in order for the present invention to be of practical application in industry and to result in particles with adequate physical properties to be incorporated into granular detergents, an anionic surfactant may be part of the paste in a concentration of more than 40%, preferably from 40% to 95%, and most preferably from 60% to 95%.

It is preferred that the moisture in the aqueous surfactant paste be as low as possible while maintaining the fluidity of the paste since low moisture results in a higher concentration of surfactant in the finished particle. Preferably, the paste contains from 5% to 40% water, more preferably from 5% to 30% water and most preferably from 5% to 20% water. A highly attractive method of reducing the moisture of the paste prior to entering the agglomerator without the problems associated with very high viscosity is to install an atmospheric dryer or a vacuum flash dryer in the line with its outlet connected to the agglomerator.

The use of high-efficiency surfactant pastes to minimize the total water content in the system during mixing, granulation and drying is preferred. Lower water contents allow (1) a higher ratio of active surfactant to builder, e.g. 1:1; (2) higher amounts of other liquids in the formulation without causing stickiness of the dough or granulated material; (3) less cooling effort due to the higher allowable granulation temperatures and (4) less effort to dry the granules to achieve the final moisture limits.

Two important parameters of the surfactant paste that can influence the mixing and granulation step are the paste temperature and the viscosity. Viscosity is a function of concentration and temperature, among others, with a range in this application from 10 Pa s to 10,000 Pa s. Preferably, the viscosity of the paste entering the system is from 20 to 100 Pa s and more preferably from 30 to 70 Pa s. The viscosity of the paste of this Invention is determined at a temperature of 70ºC and a shear rate of 25 s-1.

The paste can be introduced into the mixer at an initial temperature from its softening point (generally in the range of 40°C to 60°C) to its decomposition point (depending on the chemical nature of the paste, e.g. alkyl sulfate pastes tend to decompose above 75°C to 85°C). High temperatures reduce viscosity, making pumping the paste easier, but they result in agglomerates with lower activity. However, the use of moisture reduction steps in series (e.g. flash drying) requires the use of higher temperatures (above 100°C). In the present invention, the activity of the agglomerates is kept high due to the elimination of moisture.

The introduction of the paste into the mixer can be accomplished in many ways, from simple pouring to pumping under high pressure through small holes at the end of the line before entering the mixer. Although all of these ways are suitable for producing agglomerates with good physical properties, it has been found that in a preferred embodiment of the present invention, extrusion of the paste results in better distribution in the mixer, improving the yield of particles of the desired size. The application of high pumping pressures before entering the mixer results in increased activity in the finished agglomerates. By combining both effects and introducing the paste through holes (extrusion) sufficiently small to allow the desired flow rate but keeping the pumping pressure at the maximum possible in the system, highly advantageous results are achieved.

Highly effective surfactant paste

The activity of the aqueous surfactant paste is at least 40% and may rise to about 95%; preferred activities are from 60% to 95% and from 65% to 80%. The remainder of the paste is predominantly water, but it may comprise various processing aids. At the higher concentrations of active agent, little or no surfactant is used. Builder is required for cold granulation of the paste. The resulting concentrated surfactant granules can be added to dry builders or powders or used in conventional agglomeration processes. The aqueous surfactant paste contains an organic surfactant selected from the group consisting of anionic, zwitterionic, ampholytic and cationic surfactants or mixtures thereof. Anionic surfactants are preferred. Nonionic surfactants are used as secondary surfactants or processing aids or as the organic carrier for the optical brightener and are not included herein as an "active" surfactant. Surfactants useful herein are described in U.S. Patent No. 3,664,961, Norris, issued May 23, 1972, and U.S. Patent No. 3,919,678, Laughlin et al., issued December 30, 1975. Useful cationic surfactants also include those described in U.S. Patent No. 4,222,905, Cockrell, issued September 16, 1980, and U.S. Patent No. 4,239,659, Murphy, issued December 16, 1980. Cationic surfactants, however, are generally less compatible with the aluminosilicate materials herein and are therefore preferably employed in the present compositions in small amounts, if at all. The following examples are representative of surfactants useful in the present compositions.

Water-soluble salts of higher fatty acids, i.e. "soaps", are useful anionic surfactants in the compositions herein. These include alkali metal soaps such as sodium, potassium, ammonium and alkylammonium salts of higher fatty acids having from 8 to 24 carbon atoms and preferably from 12 to 18 carbon atoms. Soaps can be made by the direct saponification of fats and oils or by the neutralization of free fatty acids. Particularly useful are the sodium and potassium salts of mixtures of the fatty acids obtained from coconut oil and tallow, i.e. sodium or potassium tallow and coconut soaps.

Useful anionic surfactants also include the water-soluble salts, preferably the alkali metal, ammonium and alkylolammonium salts, of organic sulfuric acid reaction products which have in their molecular structure an alkyl group of 10 to 20 carbon atoms and a sulfonic acid or sulfuric acid ester group. (The term "alkyl" includes the alkyl radical of acyl groups.) Examples of this group of synthetic surfactants are the sodium and potassium alkyl sulfates, especially those obtained by sulfating the higher alcohols (C8 to C18 carbon atoms) such as those prepared by reduction of the glycerides of tallow or coconut oil; and the sodium and potassium alkylbenzenesulfonates wherein the alkyl group has from 9 to 15 carbon atoms in straight or branched chain configuration, e.g., those of the type described in U.S. Patent Nos. 2,220,099 and 2,477,383. Particularly valuable are linear, straight chain alkylbenzenesulfonates wherein the average number of carbon atoms in the alkyl group is from 11 to 13, which are abbreviated as C11-C13-LAS.

Other anionic surfactants herein are the sodium alkyl glyceryl ether sulfonates, particularly those ethers of higher alcohols derived from tallow and coconut oil; sodium coconut oil fatty acid monoglyceride sulfonates and sulfates; sodium or potassium salts of alkylphenol ethylene oxide ether sulfates having 1 to 10 ethylene oxide units per molecule and wherein the alkyl groups have 8 to 12 carbon atoms; and sodium or potassium salts of alkyl ethylene oxide ether sulfates having 1 to 10 ethylene oxide units per molecule and wherein the alkyl group has 10 to 20 carbon atoms.

Other useful anionic surfactants herein include water-soluble salts of esters of alpha-sulfonated fatty acids having 6 to 20 carbon atoms in the fatty acid group and 1 to 10 carbon atoms in the ester group; water-soluble salts of 2-acyloxy-alkane-1-sulfonic acids having 2 to 9 carbon atoms in the acyl group and 9 to 23 carbon atoms in the alkane moiety; alkyl ether sulfates having 10 to 20 carbon atoms in the alkyl group and 1 to 30 moles of ethylene. oxide; water-soluble salts of olefin sulfonates having 12 to 24 carbon atoms; and beta-alkyloxyalkane sulfonates having 1 to 3 carbon atoms in the alkyl group and 8 to 20 carbon atoms in the alkane moiety. Although the acid salts are typically discussed and used, acid neutralization can be carried out as part of the mixing step to produce a fine dispersion.

The present invention has been found to be particularly useful when the anionic surfactant paste comprises surfactants which are particularly susceptible to discoloration, such as those pastes comprising at least 5% by weight of linear alkylbenzene sulfonate, methyl ester sulfonate or paraffin sulfonate or a mixture of these.

The preferred anionic surfactant pastes are mixtures of linear or branched alkylbenzene sulfonates having an alkyl of 10 to 16 carbon atoms and alkyl sulfates having an alkyl of 10 to 18 carbon atoms. These pastes are usually obtained by reacting a liquid organic material with sulfur trioxide to produce a sulfonic acid or sulfuric acid and then neutralizing the acid to produce a corresponding acid salt. The salt represents the surfactant paste throughout this document. The sodium salt is preferred over other neutralizing agents due to the achievable performance advantages and cost of NaOH, but it is not required since other agents such as KOH can be used.

Water-soluble nonionic surfactants are also useful as secondary surfactants in the compositions of the invention. Indeed, in preferred processes, anionic/nonionic mixtures are employed. A particularly preferred paste comprises a mixture of nonionic and anionic surfactants in a ratio of from 0.01:1 to 1:1, more preferably about 0.05:1. Nonionics may be used up to an equivalent amount of the primary organic surfactant. Such nonionic materials include Compounds prepared by the condensation of alkylene oxide groups (hydrophilic in nature) with an organic hydrophobic compound which may be aliphatic or alkylaromatic in nature. The length of the polyoxyalkylene group condensed with any single hydrophobic group can be easily adjusted to obtain a water-soluble compound with the desired degree of balance between hydrophilic and hydrophobic elements.

Suitable nonionic surfactants include the polyethylene oxide condensates of alkylphenols, e.g., the condensation products of alkylphenols with an alkyl group containing 6 to 16 carbon atoms, in either a straight chain or branched chain configuration, with 4 to 25 moles of ethylene oxide per mole of alkylphenol and alkylglucoseamides.

Preferred nonionics are the water-soluble condensation products of aliphatic alcohols having 8 to 22 carbon atoms, either in straight chain or branched configuration, with 4 to 100 moles of ethylene oxide per mole of alcohol. Particularly preferred are the condensation products of alcohols having an alkyl group containing 9 to 15 carbon atoms with 4 to 80 moles of ethylene oxide per mole of alcohol; and the condensation products of propylene glycol with ethylene oxide.

Semipolar nonionic surfactants include water-soluble amine oxides containing one alkyl radical having 10 to 18 carbon atoms and two radicals selected from the group consisting of alkyl groups and hydroxyalkyl groups having 1 to 3 carbon atoms; water-soluble phosphine oxides containing one alkyl radical having 10 to 18 carbon atoms and two radicals selected from the group consisting of alkyl groups and hydroxyalkyl groups having 1 to 3 carbon atoms; and water-soluble sulfoxides containing one alkyl radical having 10 to 18 carbon atoms and one radical selected from the group consisting of alkyl and hydroxyalkyl radicals having 1 to 3 carbon atoms.

Ampholytic surfactants include derivatives of aliphatic or aliphatic derivatives of heterocyclic, secondary and tertiary amines, wherein the aliphatic radical can be either straight-chain or branched-chain, and wherein one of the aliphatic substituents has 8 to 18 carbon atoms, and wherein at least 1 aliphatic substituent has an anionic water-solubilizing group.

Zwitterionic surfactants include derivatives of aliphatic quaternary ammonium, phosphonium and sulfonium compounds wherein one of the aliphatic substituents has 8 to 18 carbon atoms.

Particularly preferred surfactants herein include linear alkylbenzenesulfonates containing 11 to 14 carbon atoms in the alkyl group; tallow alkyl sulfates; coconut alkyl glyceryl ether sulfonates; alkyl ether sulfates wherein the alkyl moiety contains 14 to 18 carbon atoms and wherein the average degree of ethoxylation is from 1 to 4; olefin or paraffin sulfonates having 14 to 16 carbon atoms; alkyldimethylamine oxides wherein the alkyl group contains 11 to 16 carbon atoms; alkyldimethylammoniopropanesulfonates and alkyldimethylammoniohydroxypropanesulfonates wherein the alkyl group contains 14 to 18 carbon atoms; higher fatty acid soaps having about 12 to 18 carbon atoms; Condensation products of C�9;-C₁₅ alcohols with 3 to 8 moles of ethylene oxide, and mixtures thereof.

Useful cationic surfactants include water-soluble quaternary ammonium compounds of the formula R4R5R6R7N+X- wherein R4 is an alkyl of 10 to 20, preferably 12 to 18 carbon atoms, and R5, R6 and R7 are each C1-C7 alkyl, preferably methyl; X- is an anion, e.g. chloride. Examples of such trimethylammonium compounds include C12-14 alkyl trimethylammonium chloride and cocoalkyl trimethylammonium methosulfate. Other cationic surfactants, including choline esters, may be used.

Particularly preferred surfactants for use herein include sodium linear C₁₁-C₁₃ alkylbenzenesulfonate; alpha-olefinsulfonates; triethanolammonium C₁₁-C₁₃ alkylbenzenesulfonate; alkyl sulfates (from tallow, coconut, palm oil or synthetic origin, e.g. C₄₅); sodium alkyl sulfates; Me ethyl ester sulfonate; sodium coconut alkyl glyceryl ether sulfonate; the sodium salt of a sulfated condensation product of a tallow alcohol with about 4 moles of ethylene oxide; the condensation product of a coconut fatty alcohol with about 6 moles of ethylene oxide; the condensation product of tallow fatty alcohol with about 11 moles of ethylene oxide; the condensation product of a fatty alcohol having 14 to 15 carbon atoms with about 7 moles of ethylene oxide; the condensation product of a C₁₂-C₁₃ fatty alcohol with about 3 moles of ethylene oxide; 3-(N,N-dimethyl-N-coconut alkylammonio)-2-hydroxypropane-1-sulfonate; 3-(N,N-dimethyl-N-coconut alkylammonio)-propane-1-sulfonate; 6-(N-dodecylbenzyl-N,N-dimethylammoniohexanoate; dodecyldimethylamine oxide; coconut alkyldimethylamine oxide; and the water-soluble sodium and potassium salts of coconut and tallow fatty acids. (As used herein, the term "surfactant" means nonionic surfactants unless otherwise specified. The ratio of surfactant (excluding nonionic agent(s)) to dry detergent builder or powder ranges from 0.005:1 to 19:1, preferably from 0.05:1 to 10:1, and more preferably from 0.1:1 to 5:1. Even more preferably, the ratios of said surfactant to builder are from 0.15:1 to 1:1 and from 0.2:1 up to 0.5:1).

Powder flow

Although the preferred embodiment of the process of the present invention involves introducing the anionic surfactant via pastes as described above, it is possible to introduce a certain amount via the powder stream, for example in the form of a blown powder. In these embodiments, it is necessary that the stickiness and moisture of the powder stream be kept at low levels, thereby preventing increased "loading" of anionic surfactant and thus the production of agglomerates with too high a concentration of surfactant. The liquid stream of a preferred agglomeration process can also be used to introduce other surfactants and/or polymers. This can be done by premixing the surfactant. tive agent into a liquid stream or, alternatively, by introducing different streams into the agglomerator. These two procedures can produce differences in the properties of the final particles (in terms of dispersion, swelling, dissolution rate, and others), particularly if mixing of the surfactants is allowed prior to particle formation. These differences can be exploited to the advantage of the intended application in each preferred method.

It has also been found that by applying the technology described here, it is possible to incorporate higher amounts of certain chemicals (e.g., non-ionics, citric acid) into the finished formulation than would be possible by other known processing routes, without adversely affecting some key components of the matrix (packing, compaction, etc.).

Mixing the fine dispersion and granulation

The term "mixing the fine dispersion and/or granulating" as used herein means mixing and/or granulating the mixture in a fine dispersion mixer at a blade tip speed of 5 m/s to 50 m/s, unless otherwise specified. The total residence time in the mixing and granulating process is preferably on the order of 0.1 to 10 min., more preferably 0.1 to 5 min., and most preferably 0.2 to 4 min. The more preferred tip speeds in mixing and granulating are 10 to 45 m/s and 15 to 40 m/s.

Any device, device or unit suitable for processing surfactants can be used to carry out the process according to the invention. Suitable apparatus include, for example, falling film sulfonation reactors, decomposition tanks and esterification reactors. For mixing/agglomeration, any of a number of mixers/agglomerators can be used. In a preferred embodiment, the process of the invention is carried out continuously. Particularly preferred are Mixers of the FukaeR FS-G series manufactured by Fukae Powtech Kogyo Co., Japan; this apparatus consists essentially of a bowl-shaped vessel accessible through an opening on the top and equipped near its base with an agitator with a substantially vertical axis and a cutting device arranged on a side wall. The agitator and the cutting device can be operated independently of each other and at different variable speeds. The vessel can be equipped with a cooling jacket or, if necessary, a cryogenic unit.

Other similar mixers which have been found to be suitable for the process of the invention include those of the DiosnaR series from Dierks & Söhne, Germany; and the Pharma MatrixR from T. K. Fielder Ltd., England. Other mixers which are believed to be suitable for use in the process of the invention are those of the FujiR VG-C series from Fuji Sangyo Co., Japan, and the RotoR from Zanchetta & Co srl., Italy.

Other suitable preferred equipment may include the EirichR RV series manufactured by Gustau Eirich Hardheim, Germany; LödigeR FM series for batch mixing; Baud KM series for continuous mixing/agglomeration manufactured by Lödige Maschinenbau GmbH, Paderborn, Germany; DraisR T160 R series manufactured by Drais Werke GmbH, Mannheim, Germany; and WinkworthR RT 25 series manufactured by Winkworth Machinery Ltd., Berkshire, England.

The Littleford Mixer, Model No. FM-130-D-12, with internal cutting blades, and the Cuisinart Food Processor, Model No. DCX-Plus with 7.75 inch (19.7 cm) blades are two examples of suitable mixers. Any other mixer for mixing a fine dispersion and granulation which allows a residence time on the order of 0.1 to 10 minutes can be used. The "turbine-type" propeller mixer with several blades on an axis of rotation is preferred. The invention can be carried out as a batch or continuous process.

Operating temperatures

Preferred operating temperatures should also be as low as possible, as this results in a higher concentration of surfactant in the final particle. Preferably, the temperature during agglomeration is less than 80°C, more preferably from 0°C to 70°C, even more preferably from 10°C to 60°C, and most preferably from 20°C to 50°C. Lower operating temperatures useful in the process of the present invention can be achieved by a variety of methods known in the art, such as cooling with nitrogen, jacketing the device with cooling water, adding solid CO2, and the like, with a preferred method being that with solid CO2 and the most preferred method being cooling with nitrogen.

A highly attractive approach in a preferred embodiment of the present invention to further increase the concentration of surfactant in the final particles is to add other elements that result in an increase in viscosity and/or melting point and/or a reduction in fast tack to a liquid stream containing the anionic surfactant and/or other surfactants. In a preferred embodiment of the process of the present invention, the addition of these elements can be made directly into the line as the paste is pumped into the agglomerator. Examples of these elements can be various powders as described in more detail hereinafter.

Finished agglomerate composition

The present invention provides high density granules for use in detergent compositions. A preferred composition of the final agglomerate for incorporation into granulated detergents has a high concentration of surfactant. By increasing the concentration of surfactant, the particles/agglomerates obtained by the present invention are suitable for These particle agglomerates, containing a high concentration of surfactants, require fewer final treatment processes to obtain the final agglomerates, thus freeing up large amounts of processing aids (inorganic powders and others) that can be used in other processing steps of the overall detergent manufacturing process (spray drying, dust removal, and others).

The granules prepared according to the present invention are large, low dusting and free flowing and preferably have a bulk density of up to 1.0 g/cm³, more preferably from 0.6 g/cm³ to 0.8 g/cm³. The weight average particle size of the particles of the invention is from 200 µm to 1,000 µm. The preferred granules so formed have a particle size range of from 200 µm to 2,000 µm. The more preferred granulation temperatures range from 10°C to 60°C and most preferably from 20°C to 50°C.

Drying

The desired moisture content of the free-flowing granules of the invention can be adjusted to levels suitable for the intended application by drying them in conventional powder drying equipment such as fluid bed dryers. When using a hot air fluid bed dryer, care must be taken to avoid decomposition of the heat sensitive components of the granules. It is also advantageous to provide a cooling step prior to large scale storage. This step can also be carried out in a conventional fluid bed operated with cool air. The drying/cooling of the agglomerates can also be carried out in any other equipment suitable for drying powders such as rotary dryers and others.

For detergent applications, the final moisture content must be kept below the levels at which the agglomerates can be stored and transported in large quantities. The exact moisture content depends on the composition decomposition of the agglomerate, but it will typically be at levels of 1% to 8% of free water (that is, water that is not bound to any crystalline species in the agglomerate), and more typically 1% to 4%.

Detergent builders and powders

Any compatible detergent builder or combination of builders or powders may be used in the process and compositions of the present invention.

The detergent compositions obtained according to the invention can contain crystalline aluminosilicate ion exchange material of the formula:

Naz[(AlO2 )z · (SiO2 )y] · xH2 O

wherein z and y are at least 6, the molar ratio of z to y is from 1.0 to 0.4; and z is from 10 to 264. Amorphous, hydrated aluminosilicate materials useful in the present invention have the empirical formula

Mz(zAlO₂ · ySiO₂),

wherein M is sodium, potassium, ammonium or substituted ammonium, z is from 0.5 to 2 and y is 1; this material has a magnesium ion exchange capacity of at least 50 mg equivalents of CaCC₃ hardness per gram of anhydrous aluminosilicate. Hydrated sodium zeolite A having a particle size of 1 µm to 10 µm is preferred.

The aluminosilicate ion exchange framework materials herein are in hydrated form and contain from 10% to 28% water by weight when crystalline and optionally even higher amounts of water when amorphous. Highly preferred crystalline aluminosilicate ion exchange materials contain from 18% to 22% water in their crystal matrix. The crystalline aluminosilicate ion exchange materials are further characterized by a particle size diameter of from 0.1 µm to 10 µm. Amorphous materials are often smaller, e.g., down to less than 0.01 µm. More preferred ion exchange materials have a particle size diameter of from 0.2 µm to 4 µm. The term "particle size diameter" as used herein represents the average particle size diameter of a given ion exchange material as determined by conventional analytical techniques such as microscopic determination using a scanning electron microscope. The crystalline aluminosilicate ion exchange materials herein are conventionally further characterized by their calcium ion exchange capacity, which is at least 200 mg-equivalents of CaCO3 water hardness/g of aluminosilicate, calculated on an anhydrous basis, and which generally ranges from 300 mg-eq/g to 352 mg-eq/g. The aluminosilicate ion exchange materials are further characterized by their calcium ion exchange rate, which is at least 0.13 g Ca²⁺/L/min/g/L (2 grains Ca²⁺/gallon/min/g/gallon) of aluminosilicate (on anhydrous basis) and generally in the range of 0.13 g Ca²⁺/L/min/g/L (2 grains/gallon/min/g/gallon) to 0.39 g Ca²⁺/L/min/g/L (6 grains/gallon/min/g/gallon) based on calcium ion hardness. Aluminosilicates optimal for builder purposes exhibit a calcium ion exchange rate of at least 0.26 g Ca²⁺/L/min/g/L (4 grains/gallon/min/g/gallon).

The amorphous aluminosilicate ion exchange materials conventionally have a Mg2+ exchange capacity of at least 50 mg-eq CaCO3/g (12 mg Mg2+/g) and a Mg2+ exchange rate of at least 0.065 g Mg2+/L/min/g/L (1 grain/- gallon/min/g/gallon). Amorphous materials do not show an observable diffraction pattern when examined by copper radiation (1.54 angstrom units).

Aluminosilicate ion exchange materials useful in the practice of this invention are commercially available. The aluminosilicates useful in this invention may be crystalline or amorphous in structure and may be naturally occurring aluminosilicates or synthetically obtained. A process for preparing aluminosilicate ion exchange materials is contained in U.S. Patent No. 3,985,669, Krummel et al., issued October 12, 1976. Preferred synthetic crystalline aluminosilicate ion exchange materials useful in this invention are known under the designations Zeolite A, Zeo lith B and zeolite X. In a particularly preferred embodiment, the crystalline aluminosilicate ion exchange material has the formula

Na12[(AlO2)12(SiO2)12] xH2O,

wherein x is from 20 to 30, especially 27, and has a particle size of generally less than 5 µm.

The granular detergents of the present invention may contain neutral or alkaline salts having a pH in solution of 7 or above and may be either organic or inorganic in nature. The builder salt helps to ensure the desired density and bulk density of the detergent granules obtained in accordance with the present invention. Although some of the salts are inert, many of them may also serve as detergent builder materials in the laundry wash solution.

Examples of neutral water-soluble salts include the alkali metal, ammonium or substituted ammonium chlorides, fluorides and sulfates. The alkali metal salts and especially the sodium salts of the foregoing are preferred. Sodium sulfate is typically used in detergent granules and is a particularly preferred salt. Citric acid and generally any other organic or inorganic acid can be incorporated into the detergent granules of the present invention so long as it is chemically compatible with the rest of the agglomerate composition.

Other useful water-soluble salts include the compounds conventionally known as detergent builder materials. Builders are generally selected from the various water-soluble alkali metal, ammonium or substituted ammonium phosphates, polyphosphates, phosphonates, polyphosphonates, carbonates, silicates, borates and polyhydroxysulfonates. Preferred are the alkali metal salts, particularly the sodium salts, of the foregoing.

Specific examples of inorganic phosphate builders are sodium and potassium tripolyphosphate, pyrophosphate, polymer res metaphosphate having a degree of polymerization of 6 to 21 and orthophosphate. Examples of polyphosphonate builders are the sodium and potassium salts of ethylene-1,1-diphosphonic 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 suitable phosphorus builder compounds are contained in U.S. Pat. Nos. 3,159,581, 3,213,030, 3,422,021, 3,422,137, 3,400,176 and 3,400,148.

Examples of inorganic non-phosphorus builders are sodium and potassium carbonate, bicarbonate, sesquicarbonate, tetraborate decahydrate and silicate with a molar ratio of SiO₂ to alkali metal of 0.5 to 4.0, preferably 1.0 to 2.4.

The compositions prepared by the process of the present invention do not require excess carbonate for processing and preferably contain no more than 2% of finely divided calcium carbonate as described in U.S. Patent No. 4,196,093, Clarke et al., issued April 1, 1980, and are preferably free of the latter.

As mentioned above, powders commonly used in detergents such as zeolite, carbonate, silica, silicate, citrate, phosphate and perborate, and processing aids such as starch can be used in preferred embodiments of the present invention.

Polymers

Also useful are various organic polymers, some of which can also serve as builders to improve detergent action. Among such polymers may be mentioned sodium carboxy-lower alkyl celluloses, sodium lower alkyl celluloses and sodium hydroxy-lower alkyl celluloses such as sodium carboxymethyl cellulose, sodium methyl cellulose and sodium hydroxypropyl cellulose, polyvinyl alcohols (which often also contain some polyvinyl acetate), polyacrylamides, polyacrylates and various copolymers such as those of maleic acid and acrylic acid. The molecular weights of such polymers vary e range widely, but they are most commonly in the range of 2,000 to 100,000.

Polymeric polycarboxylate builders are listed 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.

Optional ingredients

Other ingredients conventionally employed in detergent compositions may be included in the compositions of the present invention. These include flow aids, dye particles, bleaches and bleach activators, foam enhancing or foam suppressing agents, antifoaming and anticorrosive agents, soil suspending agents, soil release agents, fillers, germicides, pH adjusters, non-builder sources of alkalinity, hydrotropes, enzymes, enzyme stabilizing agents, chelating agents and perfumes.

Particulate foam suppressors can also be incorporated, either directly into the agglomerates obtained according to the invention via the powder stream in the agglomerator, or into the final composition by dry addition. Preferably, the foam suppressing activity of these particles is based on fatty acids or silicones.

EXAMPLES

The terms "LAS" and "AS" as used herein mean "sodium laurylbenzene sulfonate" and "alkyl sulfate", respectively. "MES" means sodium methyl ester sulfonate. The terms such as "C₄₅" mean C₁₄ and C₁₅ alkyl, unless otherwise specified. TAS means sodium tallow alkyl sulfate. Dobanol 45E7 is a C₁₄/C₁₅ alcohol ethoxylate containing 7 ethylene oxide units and is manufactured by Shell Co. AE3S be indicates sodium alkyl ether sulfate with an average of 3 ethoxy groups per molecule.

Highly effective base granules (agglomerates) are produced from a highly effective surfactant paste and a powder mixture using a small food processing device (Braun (trade mark) Multipractic Plus Electronic de luxe).

The powder mixture consisted of

Sodium silicate (3 Na) 11.5%

Sodium carbonate 50.5%

Carboxymethylcellulose 1.6%

Zeolite A 36.4%

The high performance surfactant paste comprised 18% water and a total surfactant activity (including the optical brightener, if present) of 78%. The anionic surfactants were present in the ratio of 74:24:2 of LAS:TAS:AE3S.

In each trial, 300 g of this powder mixture was placed in a mixing bowl and 110.5 g of a high potency paste was added slowly at 50ºC while the food processor mixer was operating at its highest speed. After about 30 seconds, the cutter speed was reduced to a minimum level and water was added slowly until granulation occurred, resulting in particles with a mean diameter of 400 µm to 600 µm. The wet agglomerates were then dried for about 15 minutes in a fluidized bed with an air inlet temperature of 60ºC. The resulting equivalent relative humidity (eRH) of the agglomerates was 10% to 15%.

In the following Examples 1 to 5, different amounts of nonionic surfactant (Dobanol 454E7 (trade mark) from Shell) and optical brightener (4,4'-bis-{[2-morpholino-4-anilino-1,3,5-trizian-6-yl]amino}stilbene-2,2'-disulfonate) (Color Index: Fluorescent Brightener No. 71, published by the Society of Dyers and Colorists and the American Association of Textile Chemists and Colorists) into the paste before agglomeration in the food processing equipment. The resulting particles were examined for their color.

In Example 1, the powdered optical brightener was intimately mixed with the high-performance surfactant paste for 15 minutes in a Drais Kneader (trademark; planetary mixer and kneading machine type FH1.55 from Draiswerke GmbH) which was maintained at 50ºC and under a slight vacuum to avoid aeration of the paste. In Examples 2 and 3, the powdered optical brightener was first intimately dispersed in the non-ionic surfactant at 50ºC using a high-speed mixer. This dispersion was then mixed into the high-performance anionic surfactant paste in the same manner as in Example 1. In Comparative Example 4, the paste was treated in a kneader as in the previous examples, but no non-ionic agent and no brightener were added. In Comparative Example 5, the nonionic surfactant was mixed with the anionic surfactant paste in a kneader, but no optical brightener was added.

In each example, the agglomerates were separated between Tyler mesh 20 (corresponding to a mesh size of 850 µm) and Tyler mesh 35 (corresponding to a mesh size of 425 µm) to remove the fine and coarse particles, the remaining fraction being evaluated for colour by the Hunter Laboratory method (Munter, RS, J. Opt. Soc. Amer 48,597 (1958)) using a commercially available Hunterlab colour/difference meter model D25-2 from Elscoserv NV.

The color values of the agglomerates were:

It is known from consumer appearance tests that agglomerates with low L values (< 85%) and/or negative a values (a < 0), which tend to be greenish, and/or high b values (b > 6), which tend to be yellowish, can be easily identified from the granular composition and contribute to a poor product appearance.

In this regard, Examples 1 to 3, which contain the optical brightener processed as described herein, have the best color. In particular, Examples 2 and 3, in which the brightener was premixed with a nonionic surfactant, have improved color properties.

In Examples 6 and 7, agglomerates were prepared in a Loedige FM mixer/agglomerator. The powder mixture consisted of:

Sodium silicate (3 Na) 17.5%

Sodium carbonate 32.5%

Carboxymethylcellulose 2.4%

Zeolite A 47.6%

The high performance surfactant paste comprised 18% water and a total surfactant activity (including the dye solution, if present) of 78%. The anionic surfactants were present in the ratio of 74:24:2 of LAS:TAS:AE3S.

In both experiments, 25.8 kg of the powder mixture was fed into the mixer/granulator together with 14.3 kg of the high performance surfactant paste at 50ºC. Both the paddles and cutters of the mixer/agglomerator were operated for about 100 seconds, producing agglomerates with a mean particle size of 400 to 600 µm. The agglomerates were dried in a fluidized bed with an air inlet temperature of 80ºC for about 15 minutes, after which they were cooled to 35ºC using ambient air before discharge. The eRH of the agglomerates is from 10% to 15%.

In Example 6, a dye solution is prepared consisting of 2 parts Special Fast Blue G FW, ground (Acid Blue 127/l) supplied by Bayer UK Ltd, at a concentration of 25%, and 1 part Levanyl Violet BNZ (Pigment Violet 23) supplied by Bayer UK Ltd, at a concentration of 25%.

This dye mixture was then diluted to a 0.1% aqueous solution before mixing with the highly effective surfactant paste and subsequent processing into agglomerates in the manner described above. 90 ml of the 0.1% solution was mixed with 15 kg of paste.

In each example, the agglomerates were sieved between Tyler mesh 20 (corresponding to a mesh size of 850 µm) and Tyler mesh 35 (corresponding to a mesh size of 425 µm) to remove the fine and coarse particles, after which the remaining fraction was classified for colour by the Hunter-La boratorium method (Hunter, RS, J. Opt. Soc. Amer 48,597 (1958) using a commercially available Hunterlab Color/Difference Meter Model D25-2 from Elscoserv NV.

The color values of the agglomerates were:

Example 6 (with dye) has a less yellow coloration than Example 7, in which no dye was added.

Claims (11)

1. A process for producing a high-performance granular detergent comprising the steps of dispersing an organic detergent component with particles of an inorganic component in the presence of a dye or an optical brightener, comprising the steps (i) preparing a high performance paste containing at least 40 wt% of anionic surfactant salts, by neutralizing the corresponding acids, which paste has a viscosity of at least 10 Pa·s, measured at a temperature of 70°C and a shear rate of 25 s⊃min;1; (ii) granulating said high potency paste to form agglomerates in a high shear mixer/granulator with an effective amount of detergent powders; wherein the dye or brightener or a mixture thereof is either added in a liquid form in step (i) of the process into a circulation reactor in which the anionic detergent acids are neutralized to form their salts, or wherein the colorant or brightener is added in a liquid form by premixing with the high-performance detergent paste in a batch mixing tank or continuously in an extruder, or wherein the colorant or brightener in liquid form is pumped or sprayed into the high shear mixer/granulator in step (ii) of the process either as an aqueous solution or as a premix with a carrier. 2. A process according to claim 1, wherein the dye or brightener is selected from those dyes or brighteners which emit at least 70% of light in the visible light range below a wavelength of 500 nm. 3. A high performance detergent paste composition comprising a dye or an optical brightener or a mixture of these, characterized in that said paste composition comprises at least 40% by weight of salts of anionic surfactants and that the paste composition has a viscosity of at least 10 Pa·s, measured at a temperature of 70°C and a shear rate of 25 s⁻¹. 4. A high performance detergent paste composition according to claim 3, which comprises at least 5% by weight of linear alkylbenzene sulfonate, methyl ester sulfonate, paraffin sulfonate or a mixture thereof. 5. A composition according to claim 3 or 4, wherein said dye is selected from Levanyl Violet BNZ (trade name) [Pigment Violet 23] and Special Fast Blue G FW Ground (trade name) [Acid Blue 127/1], both supplied by Bayer AG. 6. A composition according to any one of claims 3 to 5, wherein said dye is present in an amount of 0.1 to 5 ppm of the paste composition. 7. Composition according to one of claims 3 to 6, characterized in that the dye is added to the composition in the form of an aqueous solution. 8. Composition according to one of claims 3 to 7, characterized in that the optical brightener is chosen from the sodium salts of: 4,4'-bis-(2-diethanolamino-4-anilino-s-triazine-6-ylamino)stilbene-2:2'-disulfonate, 4,4'-bis-(2-morpholino-4-anilino-s-triazine-6-ylamino)stilbene-2:2'-disulfonate, 4,4'-Bis-(2,4-dianilino-s-triazine-6-ylamino)stilbene-2:2'-disulfonate, 4.4"-Bis-(2,4-dianilino-s-triazine-6-ylamino)stilbene-2-sulfonate, 4,4'-Bis-(2-anilino-4-(N-methyl-N-2-hydroxyethylamino)-s-triazine-6-ylamino)stilbene-2,2'-disulfonate, 4,4'-bis(4-phenyl-2,1,3-triazol-2-yl)stilbene-2,2'-disulfonate, 4,4'-Bis-(2-anilino-4-(1-methyl-2-hydroxyethylamino)-s-triazine-6-ylamino)stilbene-2,2'-disulfonate, 4,4-bis-(2-sulfostyryl)biphenyl or 4,4-bis-(4-chloro-3-sulfostyryl)biphenyl; and/or the optical brightener is selected from derivatives of bisbenzoxazolyl or 1,3-diphenyl-2-pyrazoline. 9. Composition according to claim 8, characterized in that the brightener is premixed with an organic carrier before being added to the composition. 10. Composition according to claim 9, characterized in that the carrier is a nonionic surfactant or polyethylene glycol. 11. A composition according to any one of claims 3 to 10, wherein said optical brightener is present in an amount of from 0.1% to 2% by weight of the paste composition.