CN1195834C - Process for making detergent compositions - Google Patents

Abstract

The present invention relates to a process comprising the steps of: (i) mixing together at least two non-surfactant additives to form a premix; (ii) spraying substantially all of the nonionic surfactant on to the premix to form a first intermediate particle; (iii) subsequently mixing the first intermediate particle with a second intermediate particle, wherein the second intermediate particle comprises substantially all of the anionic surfactant, and is substantially free of nonionic surfactant.

Description

Process for preparing detergent composition

The present invention relates to a process for the preparation of detergent compositions.

There is a trend towards higher bulk densities in commercially available granular detergents. This is beneficial both for consumer convenience and to reduce filler material.

Many attempts in the prior art in this regard have suffered from poor solubility due to slow dissolution rates or gel formation. The consequence of this during a typical wash cycle is poor product dispersibility, with the product being difficult to dispense from the dispenser box of the washing machine or from the dosing device installed inside the washing machine. This poor dispersibility is usually caused by the gel formation of particles with a high content of surfactant in contact with water. The gel prevents the proportional dissolution of the detergent powder into the wash water, which reduces the effectiveness of the powder. Even if the powder is highly dispersible and dispersed in the wash water, it can lead to adverse consequences if it does not dissolve quickly. A wash cycle has a limited duration during which the detergent should work on the clothes. This can also limit the efficacy of the powder if its cleaning action is delayed due to slow dissolution.

Engineers and formulators of this approach often find that solving these problems inevitably requires good dispersibility and good solubility. Solutions are generally found to have suitable dispersibility and suitable dissolution rates. For example, poor dispersibility of high bulk density granular detergents is often associated with surfactant enriched particles having high specific surface area, either due to high porosity or small particle size (especially "fine" particles). However, reducing the porosity and/or increasing the average particle size results in a lower dissolution rate.

WO 94/05761, published March 17, 1994, describes a final product densification step wherein substantially all of the product is sprayed with nonionic surfactants and coated with zeolites. Among them, good dispersibility and solubility properties are required.

However, it has now been found that further improvements in dispersion and dissolution properties can be obtained if the nonionic surfactant and zeolite coating is applied to only selected parts of the detergent composition, rather than to the entire detergent composition.

It is an object of the present invention to provide improved processes for the preparation of detergent compositions containing anionic surfactants, nonionic surfactants and non-surfactant additives.

Summary of the invention

The object of the present invention is achieved by a method comprising the following steps:

(i) mixing at least two non-surfactant additives together to form a premix;

(ii) spraying substantially all of said nonionic surfactant onto the premix to form first intermediate particles;

(iii) The first intermediate particle is then mixed with a second intermediate particle, wherein the second intermediate particle contains substantially all of said anionic surfactant and is substantially free of nonionic surfactant.

Detailed description of the invention

In a preferred embodiment of the invention, the first intermediate particles are formed by the following steps:

(a) mixing at least two non-surfactant additives together to form a premix; and

(b) Increase the average particle size by spraying a nonionic surfactant onto the premix and apply a finely divided particulate material, preferably an aluminosilicate.

In another preferred embodiment of the present invention, the first intermediate particles are formed by the following steps:

(a) mixing at least two non-surfactant additives together to form a premix; and

(b) spraying the nonionic surfactant onto the premix, wherein the ratio of nonionic surfactant to premix is at least 1:25;

(c) applying a first amount of finely divided particulate material, wherein the ratio of the first amount of finely divided particulate material to the nonionic surfactant applied in step (b) is less than 1:1;

(d) increasing the average particle size of the premix by mixing; and

(e) applying a second amount of finely divided particulate material, wherein the ratio of the second amount of finely divided particulate material to the nonionic surfactant applied in step (b) is greater than 1:1.

The method of the invention results in a narrow particle size distribution and a sharp peak defined mean. Preferably the average particle size is from 800 to 1200 microns, with a particle size distribution having a standard deviation of less than 100 microns. More preferably the average particle size is from 900 to 1100 microns, with a particle size distribution having a standard deviation of less than 50 microns.

Non-surfactant additives may include any detergent additive such as bleach, especially perborate or percarbonate; inorganic salts, especially carbonate, bicarbonate, silicate, sulfate, or citric acid Salts; Chelating Agents, Enzymes.

Preferably the first intermediate particle contains less than 5% by weight anionic surfactant, more preferably the first intermediate particle contains less than 1% by weight anionic surfactant.

The finely divided particulate materials used in the present invention include aluminosilicates having the following empirical formula:

M _z (zAlO ₂ ) _y ]·xH ₂ O

wherein z and y are integers of at least 6, the molar ratio of z to y ranges from 1.0 to about 0.5, and x is an integer of about 15 to 264.

Useful aluminosilicate ion exchange materials are commercially available. These aluminosilicates may be of crystalline or amorphous structure and may be naturally occurring aluminosilicates or synthetically derived. A method of preparing aluminosilicate ion exchange materials is disclosed in US Patent 3,985,669, issued October 12, 1976 to Krummel et al. Preferred synthetic crystalline aluminosilicate ion exchange materials for use herein are commercially available under the designations Zeolite A, Zeolite P(B), Zeolite MAP, Zeolite X and Zeolite Y. In a particularly preferred embodiment, the crystalline aluminosilicate ion exchange material has the formula:

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

wherein x is from about 20 to about 30, especially about 27. This material is called Zeolite A. Dehydrated zeolites (x = 0-10), and "overdried" zeolites (x = 10-20) are also useful herein. "Overdry" zeolites are particularly preferred when low humidity environments are required, for example for improving the stability of laundry bleaches such as perborate and percarbonate. The aluminosilicate preferably has a particle size diameter of about 0.1-10 microns. Preferred ion exchange materials have a particle size diameter of from about 0.2 microns to about 4 microns. The term "particle size diameter" in the present invention means the weight average particle size diameter of a given ion exchange material as determined by conventional analytical techniques such as, for example, microscopic measurements using a scanning electron microscope. The crystalline zeolite A materials of the present invention are typically further characterized by their calcium ion exchange capacity of at least about 200 meq CaCO water hardness per gram of _{aluminosilicate} , calculated on an anhydrous basis, which is typically The range is about 300 meq/gram to about 352 meq/gram. The zeolite A materials of the present invention are also characterized by their calcium ion exchange rate, which is at least about 2 grains Ca ⁺⁺ /gallon/minute/gram/gallon (0.13 grams Ca ⁺⁺ /liter/minute/gram /l) aluminosilicate (anhydrous basis), the value usually ranges from about 2 grains/gallon/min/g/gal (0.13 g Ca ⁺⁺ /l/min/g/l) to about 6 grains Rem/gal/min/g/gal (0.39 g Ca ⁺⁺ /l/min/g/l), based on calcium ion hardness. Desirable aluminosilicates for builder applications have a calcium ion exchange rate of at least about 4 grains/gallon/minute/gram/gallon (0.26 grams Ca ⁺⁺ /liter/minute/gram/liter).

Generally any nonionic surfactant can be used in the present invention, with two classes of nonionic surfactants being found to be particularly useful. These nonionic surfactants are those based on alkoxylated (especially ethoxylated) alcohols, and those based on amidation products of fatty acid esters and N-alkyl polyhydroxylamines. active agent. Such amidation products of esters and amines are generally referred to herein as polyhydroxy fatty acid amides. Particularly useful herein are mixtures comprising two or more nonionic surfactants, at least one of which is selected from the group consisting of alkoxylated alcohols and polyhydroxy fatty acid amides.

Suitable nonionic surfactants include compounds resulting from the condensation of alkylene oxides (hydrophilic) with organic hydrophobic compounds which may be aliphatic or alkylaromatic. The length of the polyoxyalkylene group condensed with any particular hydrophobic group can be readily adjusted to obtain a water-soluble compound with the desired degree of hydrophilic and hydrophobic balance.

Particularly preferred for use herein are nonionic surfactants such as polyethylene oxide condensates of alkylphenols, e.g., alkylphenols having a linear or branched alkyl backbone containing about 6 to 16 Condensates of ethylene oxide at about 4 to 25 moles per mole of alkylphenol.

Preferred nonionic surfactants are water-soluble condensates of linear or branched fatty alcohols having 8 to 22 carbon atoms with an average of up to 25 moles of ethylene oxide per mole of alcohol. Particularly preferred are condensation products of alcohols having about 9 to 15 carbon atoms with about 2 to 10 moles of ethylene oxide per mole of alcohol; and condensation products of propylene glycol with ethylene oxide. Most preferred are the condensation products of an alcohol having an alkyl group containing about 12 to 15 carbon atoms with an average of about 3 moles of ethylene oxide to the moles of alcohol.

A particularly preferred embodiment of the present invention is that the nonionic surfactant system also comprises a polyhydroxy fatty acid amide component.

Polyhydroxy fatty acid amides can be prepared by reacting fatty acid esters with N-alkyl polyhydroxy amines. Preferred amines for use in the present invention are N-(R1)-CH2(CH2OH)4-CH2-OH, where R1 is typically an alkyl group such as methyl; a preferred ester is a C12-C20 fatty acid methyl ester.

A process for the production of polyhydroxy fatty acid amides has been described in WO926073, published April 16,1992. This application describes the preparation of polyhydroxy fatty acid amides in the presence of solvents. In a very preferred embodiment of the invention is the reaction of N-methylglucamine with a C12-C20 methyl ester.

Nonionic surfactants that may be used as components of the surfactant system of the present invention include ethoxylated nonionic surfactants, glyceryl ethers, glucamides, glyceramides, glycerides, fatty acids, fatty acid esters, fatty amides , alkyl polyglycosides, alkyl polyglycol ethers, polyethylene glycols, ethoxylated alkylphenols and mixtures thereof.

The second intermediate particle of the present invention comprises an anionic surfactant. The second intermediate granules can be prepared by any method including spray drying, exfoliation, pelletizing, extrusion, tableting, and agglomeration. Agglomeration processes for the preparation of anionic surfactant particles are disclosed in the prior art, for example, in EP-A-0508543, EP-A-0510746, EP-A-0618289 and EP-A-0663439. An essential feature of the present invention is that no nonionic surfactant is sprayed into the surfactant agglomeration stream.

Non-limiting examples of anionic surfactants useful in the present invention include common C _11-18 alkylbenzene sulfonates ("LAS") and primary, branched and random C _10-20 alkyl sulfates ("LAS") _{AS " )} ^, _{C 10-18 secondary} ⁽ _{2,3 _ _} ^{_ _} _{_ _ _} ) alkyl sulfates, wherein x and (y+1) are integers of at least about 7, preferably at least about 9, and M is a water-solubilizing cation, especially sodium, an unsaturated sulfate such as oleyl sulfate, C _10-18 alkyl alkoxy sulfates ("AE _x S", especially EO1-7 ethoxy sulfates), C _10-18 alkyl alkoxy carboxylates (especially EO1-5 ethoxy carboxylates), C _10-18 glyceryl ethers, C _10-18 alkyl polyglycosides and their corresponding sulfated polyglycosides, and C _12-18 α-sulfonated fatty acid esters, methyl ester sulfonates and oils base sarcosinate.

Finally the surfactant agglomerates and lamellar particle additives are mixed, optionally with additional additives, to form the finished detergent composition.

The various mixing steps of the present invention can be carried out in any suitable mixer, such as ^Eirich® , series RV produced by Gustau Eirich Hardheim, Germany; ^Lödige® produced by Lodige Machinenbau GmbH, Paderbirn, Germany FM for batch mixing series, Baud KM series for continuous mixing/agglomeration; ^Drais® T160 series produced by DraisWerke GmbH, Mannheim, Germany; and ^Winkworth® RT25 series produced by Winkworth Machinery Ltd., Berkshire, UK; models with internal cut-off blades Mixer #FM-130-D-12 Littleford, and Cuisinart Food Processor Model #DCX-Plus with 7.75" (19.7 cm) blades. Many other mixers are commercially available that can be used for both batch and continuous mixing.

Example

Example 1 Example 2 Example 3 Example 4 Example 5

Sodium carbonate 3 2 2 7.8 -

Sodium citrate - - - - - - - 10

Sodium bicarbonate - - - - - - - 10

Percarbonate 20 16 16 - -

Perborate - - - - - - 18 -

Enzyme 1.7 2.2 2.2 1 2

Nonionic Surfactant 4 13 19 20 20

particles

Hydroxyethylenediphosphonic acid 1 1 1 1 - -

Tetraacetylethylenediamine 6 4.7 4.7 4 -

Anti-foaming agent granule 2.8 1 1 1 -

Layered silicate 15 12 12 - -

Sodium silicate (2.0R) - - - - - - 2 3

Sodium Sulfate - - - - - - - 5

Cationic Surfactant 5 - - - - -

particles

Whitening agent - - - - - - 0.2 -

58.5 51.9 57.9 53 50

All percentages are expressed as percentages by weight of the finished product unless otherwise indicated.

Nonionic surfactant granules contain 15 parts alcohol ethoxylate with an average of 5 EO groups per mole AE5, 15 parts polyhydroxy fatty acid amides, 60 parts zeolite, 5 parts fatty acid and 5 parts water, and according to EP- Prepared by the method described in A-0643130.

Antifoam granules contained 12 parts silicone oil, 70 parts starch and 12 parts hydrogenated fatty acid/tallow alcohol ethoxylate (TAE80) and were prepared according to the method described in EP-A-0495345.

The layered silicate was SKS- ^6® supplied by Hoechst.

The cationic surfactant contained 30 parts of alkyldimethylethoxyammonium chloride, 60 parts of sodium sulphate, 5 parts of alkyl sulphate and 5 parts of water and was prepared according to the method described in EP-A-0714976.

The brightener was Tinopal CDX ^(R) supplied by Ciba-Geigy.

Example 1

The additives shown under the Example 1 column in the previous table were mixed together and the particles were found to have an average particle size of 440 microns.

6.5% of nonionic surfactant (alcohol ethoxylate with an average of 5 EO groups per mole, AE5) was sprayed onto the additive mixture in the concrete mixer at 35°C using a dual-fluid spray nozzle. Add 5% Zeolite A to the concrete mixer over 1 minute. The mixer was then continued to operate and no further zeolite was added within 1.5 minutes. Finally, 8% zeolite was added over 1 minute.

The product in the concrete mixer had an average particle size of 1020 microns.

The anionic surfactant particles were then added to the concrete mixer at a level of 22%. The anionic surfactant particles contained 28 parts linear alkylbenzene sulfonate, 12 parts tallow alkyl sulfate, 30 parts zeolite, 20 parts carbonate and 10 parts water and had an average particle size of 850 microns.

The final product has an average particle size of 960 microns.

Example 2

The additives shown under the Example 2 column in the previous table were mixed together and the particles were found to have an average particle size of 390 microns.

6.5% of nonionic surfactant (AE5) was sprayed onto the additive mix in the concrete mixer at 35°C using a dual-fluid spray nozzle. 4% Zeolite A was added to the concrete mixer over 1 minute. The mixer was then continued to operate and no further zeolite was added within 1 minute. Finally 9% zeolite was added over 2 minutes.

The product in the concrete mixer had an average particle size of 1080 microns.

The anionic surfactant particles were then added to the concrete mixer at a level of 28.6%. The anionic surfactant particles contained 28 parts linear alkylbenzene sulfonate, 12 parts tallow alkyl sulfate, 30 parts zeolite, 20 parts carbonate and 10 parts water and had an average particle size of 850 microns.

The final product has an average particle size of 1030 microns.

Example 3

The additives shown under the Example 3 column in the previous table were mixed together and the particles were found to have an average particle size of 390 microns.

6.5% of nonionic surfactant (AE5) was sprayed onto the additive mix in the concrete mixer at 35°C using a dual-fluid spray nozzle. 7% Zeolite A was added to the concrete mixer in one step.

The product in the concrete mixer had an average particle size of 555 microns.

The anionic surfactant particles were then added to the concrete mixer at a level of 28.6%. The anionic surfactant particles contained 28 parts linear alkylbenzene sulfonate, 12 parts tallow alkyl sulfate, 30 parts zeolite, 20 parts carbonate and 10 parts water and had an average particle size of 410 microns.

The final product has an average particle size of 520 microns.

Example 4

The additives shown under the Example 4 column in the previous table were mixed together.

6% of non-ionic surfactant (AE5) was sprayed onto the additive mixture in the concrete mixer at 35°C using a dual-fluid spray nozzle. A total of 13% of Zeolite A was added to the concrete mixer in fractions of 1% at a time.

The product in the concrete mixer has an average particle size of 1000 microns.

The spray-dried powder was then added to the concrete mixer at a level of 28%. The spray dried granules contained 20 parts linear alkylbenzene sulfonate, 5 parts polyacrylate polymer, 5 parts chelating agent, 30 parts zeolite, 30 parts sulfate and 10 parts water and had an average particle size of 1000 microns.

The final product has an average particle size of 1000 microns.

Example 5

The additives shown under the Example 5 column in the previous table were mixed together.

7% non-ionic surfactant (AE5) was sprayed onto the additive mix in the concrete mixer at 35°C using a dual-fluid spray nozzle. A total of 13% of Zeolite A was added to the concrete mixer in fractions of 1% at a time.

The product in the concrete mixer had an average particle size of 1050 microns.

The spray-dried granules were then added to the concrete mixer at a level of 30%. The spray dried granules contained 20 parts linear alkylbenzene sulfonate, 5 parts polyacrylate polymer, 5 parts chelating agent, 30 parts zeolite, 30 parts sulfate and 10 parts water and had an average particle size of 1000 microns.

The final product has an average particle size of 1020 microns.

Claims (3)

1. A method for preparing a detergent composition containing anionic surfactants, nonionic surfactants and non-surfactant additives, the method is characterized by the following steps: (a) mixing at least two non-surfactant additives together to form a premix; (b) spraying all of said nonionic surfactants onto the premix, wherein the ratio of nonionic surfactant to premix is at least 1:25; (c) applying a first amount of finely divided particulate material, wherein the ratio of the first amount of finely divided particulate material to the nonionic surfactant applied in step (b) is less than 1:1; (d) increasing the average particle size of the premix by mixing; (e) applying a second amount of finely divided particulate material to form the first intermediate particle, wherein the ratio of the second amount of finely divided particulate material to the nonionic surfactant applied in step (b) is greater than 1:1, wherein The first intermediate particles have an average particle size of 900 to 1100 microns, with a particle size distribution having a standard deviation of less than 50 microns; and (f) The first intermediate particle is then mixed with a second intermediate particle, wherein the second intermediate particle contains all of said anionic surfactant and no nonionic surfactant. 2. A method according to claim 1, wherein the finely divided particulate material is an aluminosilicate. 3. The method according to claim 1, wherein the at least one non-surfactant additive is a bleaching agent selected from the group consisting of perborates, percarbonates and mixtures thereof.