EP0759969A1

EP0759969A1 - Powder detergent composition comprising stabilized percarbonate

Info

Publication number: EP0759969A1
Application number: EP95920966A
Authority: EP
Inventors: Daniel Joubert; Patrick Boittiaux
Original assignee: Rhone Poulenc Chimie SA
Current assignee: Rhodia Chimie SAS
Priority date: 1994-05-20
Filing date: 1995-05-19
Publication date: 1997-03-05
Also published as: FI964627A0; NO964888D0; FR2720074B1; NO964888L; WO1995032273A1; AU2620295A; FR2720074A1; FI964627A

Abstract

Powder detergent composition for machine washing clothes and containing a bleaching system comprising sodium or potassium percarbonate, optionally activated by a bleach activator, stabilized by a cogranulate consisting of sodium or potassium carbonate, sodium or potassium silicate and water combined with alkaline silicate, the weight ratio of water combined with silicate to silicate being 33/100-120/100. The invention also concerns the use of such cogranulates for stabilizing a bleaching agent system comprising percarbonate.

Description

STABILIZED PERCARBONATE POWDER DETERGENT COMPOSITION.

The present invention relates to a detergent powder composition for washing laundry in a washing machine containing a bleaching system based on alkali metal percarbonate. The purpose of the bleaching systems included in detergent compositions for washing the laundry is to remove colored stains by oxidation, to disinfect and deodorize the laundry.

The bleaching agents usually used are oxygen donors of the persalt or sodium perborate type which release H ₂ O ₂ in solution.

However, due to the negative impact of boron on the environment, it appears desirable to gradually replace perborate with percarbonate. However, sodium percarbonate is a less stable bleaching agent than sodium perborate and other similar products that carry hydrogen peroxide, especially when the laundry is stored in humid atmospheres, which has up to 'now limited its use in consumer formulations.

Many solutions have been proposed to remedy the instability of percarbonate and, among other products, sodium silicate is known as a stabilizing agent for percarbonate.

The object of the invention is to provide powdered detergent compositions for washing machine in a machine based on stabilized percarbonate.

It has been found, surprisingly, that cogranules consisting of alkali metal carbonate, alkali metal silicate and water associated with the silicate, when they are introduced by simple powder mixing in a formulation containing percarbonate sodium as a bleaching agent, improve the storage stability of percarbonate.

Such cogranules are the subject of European patent application EP-A-0488 868 filed by the Applicant. These products are known for their "builder" properties and their detergent behavior, which is particularly suitable for washing machine and dishwasher applications. They are used as tripolyphosphate (TPP) substituents in these detergent compositions; in fact, they provide in particular both the dispersing power of TPP thanks to the silicate and the softening effect of the washing water thanks to the carbonate.

Thus, the invention relates to a detergent powder composition for washing clothes in a washing machine containing a stable bleaching system based on sodium or potassium percarbonate, characterized in that it contains as stabilizing agent of said percarbonate a cogranulate consisting of sodium or potassium carbonate, sodium or potassium silicate and water associated with silicate, the weight ratio (water associated with silicate) / (silicate expressed as dry) being 33 / 100 to 120/100.

The co-granules known from EP-A-0488 868 are obtained by adsorption and / or absorption of an aqueous solution of hydrated alkali metal silicate on a particulate inorganic support chemically inert with respect to the silicate, namely a metal carbonate alkaline.

They are characterized in particular by their water content "associated" with silicate. By this expression, we mean the water remaining associated with the silicate after adsorption and / or absorption, that is to say the water of the supported solution which is not combined with the mineral support, in particular in the form of 'crystallized hydrate. The amount of mineral support used contact with the silicate solution is adjusted so that the weight ratio (water associated with the silicate) / (sili¬ cate expressed as dry) is greater than 33/100. The upper limit of the weight ratio (water remaining associated with the silicate) / (silicate expressed in dry) corresponds to the limits for which a silicate is kept in powder form with fluid flow ("free flowing"), that is to say usable in detergency. To fix the ideas, the weight ratio (water remaining associated with silicate) / - (silicate expressed in dry) must be less than or equal to approximately 120/100.

The preparation of the cogranules can be done by any available means of bringing the silicate solution into contact with the carbonate particles. A preparation process consists in (a) spraying an aqueous solution based on alkali metal silicate or based on a mixture of silicate and alkali metal carbonate on a moving bed of particles based on alkali metal carbonate or based on the identical silicate-carbonate mixture cited above, traveling in a rotary granulation device, the speed of movement of the particles, the thickness of the moving bed and the flow rate of the sprayed solution being such that each particle is transformed into a plastic cogranulate by coming into contact with other particles, (b) drying, optionally, said co-granules obtained in (a), these steps being implemented so that the weight ratio (water associated with silicate) / (sili¬ cate expressed in sec) remains between 33/100 and 120/100.

Preferably, between steps (a) and (b), the cogranules are subjected to a densification operation.

Thus, mention may be made, by way of example of agents based on silicate and carbonate such as described above, Nabion ® manufactured and marketed by Rhône-Poulenc.

The alkali metals of the silicate and of the carbonate can be identical or different and chosen from sodium and potassium. However, it is preferred to use a sodium carbonate and silicate.

The sodium silicate advantageously has a Si0 ₂ / Na ₂ 0 molar ratio of 1.6 to 3.5, preferably 1.8 to 2.6 and very particularly close to 2. The cogranulate can, in in addition, contain a siliconate or siliconate derivatives, that is to say salts of siliconic acid or its derivatives.

These products correspond in particular to the following formula (1):

R-Si (0M) _m (0H) ₃ __ (1)

and / or the condensation products thereof, formula in which R is a hydrocarbon residue generally of 1 to 18 carbon atoms, optionally substituted by an amino, ether, ester, epoxy, mercapto, cyano, polyglycol group; m is a number varying from 0.1 to 3; M is an alkali or alkaline earth metal or an ammonium or phosphonium group. Preferably, R is a hydrocarbon residue of

1 to 10 carbon atoms and more particularly from 1 to 6 carbon atoms.

More specifically, R can be an alkyl radical, for example methyl, ethyl, propyl, butyl, isobutyl; an alkenyl radical, for example vinyl; an aryl radical, for example phenyl or naphthyl; an aralkyl radical, for example benzyl or phenylethyl; an alkylaryl radical, for example tolyl, xylyl; or an araryl radical such as biphenylyl. For M, we can more particularly cite sodium or potassium, as well as the groups N ^* R ' ₄ and P ⁺ R' ₄ , in which R ', identical or different, represent hydrocarbon residues of 1 to 6 carbon atoms. Use is more particularly made of alkali metal silicates. The alkaline earth siliconates can also be used.

Likewise, particular use is made of alkylsiliconates and in particular alkaline alkylsiliconates, for example sodium or potassium methylsiliconates.

It is also possible to use the siliconates of formula (1) in which R is a vinyl or phenyl radical, and more particularly the alkali siliconate of this type.

The siliconates can be prepared for example by hydrolysis of the corresponding silanes presenting 3 hydrolysable groups such as halogen atoms, alkoxy radicals, followed by dissolution of the product obtained in a solution of a strong inorganic base in proportions such that there is at least one equivalent in base per atom of silicon (see for example the patents US-A-2,441,422 and US-A-2,441,423).

As an example of commercially available siliconates of this type, mention may in particular be made of Rhodorsil Siliconate 51T®, sold by Demand, which is a solution of approximately 50% of dry extract of potassium methylsiliconate.

By products derived from siliconates is meant here the condensation products of the products corresponding in particular to formula (1) described above, or those resulting from the at least partial polymerization of silicone compounds or polymers.

It is known, for example, that the alkali metal alkylsiliconates can be converted into polyalkylsi- loxanes, in particular by the action of carbon dioxide or other acidifying agent.

It goes without saying that, in the context of the present invention, it is possible to use in combination two or more siliconates or derivatives.

The siliconate and / or its derivatives are introduced into the cogranule by bringing an aqueous solution of siliconate (or its derivatives) into contact with the other solid and liquid components, namely carbonate and silicate.

Preferably, the siliconate solution is added by any means known per se to a silicate-carbonate cogranule described above.

An example of a general process for preparing a cogranule containing a siliconate is as follows, which consists in (1) implementing a process for preparing the agents in the form of cogranules described in EP-A-0488 868, (2) to be used contact an aqueous solution of siliconate or its derivatives on the cogranules thus obtained and (3) possibly to be dried.

This addition of siliconate (and its possible drying) is carried out in a controlled manner so as to respect a weight ratio (water associated with silica¬ te) / (silicate expressed as dry) of the order of 33/100 to 120/100 as indicated above.

The maximum amount of siliconate or its derivatives present in this product corresponds to the limit of the adsorbent and / or absorbent power of the agent, as described above. However, to fix ideas, the maximum limit of adsorption and / or absorption of an agent based on alkali metal silicate supported on alkali metal carbonate and water associated with silicate, the ratio (water associated silicate) / (silicate expressed as dry) being greater than or equal to 33/100, is generally situated around 13%, preferably 10% of its total weight,

The minimum quantity of siliconate or of its derivatives present in this product preferably corresponds to 2% of the total weight of the product, and more advantageously to 3%.

In a powder washing composition according to the invention, the bleaching system comprises a conventional percarbonate and said co-granules. Percarbonate does not undergo any particular treatment. The co-granules, whether or not containing siliconates, stabilize the percarbonate without the need for intimate contact between the two products. Unexpectedly, the improvement is obtained by a simple dry mixing of the pulverulent or granular products. The cogranule is introduced in an advantageous manner at a rate of 8 to 22% by weight of the composition and preferably from 12 to 18%. Sodium or potassium percarbonate is advantageously introduced in an amount of 6 to 20% by weight of the composition and preferably from 7 to 13%.

To obtain a bleaching effect at low temperature, it is possible to use an activated bleaching system which comprises, in addition to percarbonate, a bleaching activator, in particular tetraacetylethylenedia mine (TAED), pentaacetylglucose (PAG), tetraaceous - tylglycoluryl (TAGU) or isonanoyloxybenzènesulfonate (ISONOBS). activator is preferably present in an amount of 0.5 to 6% by weight of the composition, and more preferably from 1 to 5% by weight.

The rate of addition of the activator can be at two levels, which corresponds to so-called "standard" formulations for the low level and to so-called formulations. "compact" for the high level.

A powder washing composition in accordance with the invention can be prepared from the above-mentioned constituents by simple dry mixing of the bleaching agent, and optionally the bleaching activator, with the stabilizing agent. , in the proportions indicated above, and addition of other conventional components of the detergent compositions for washing the laundry, indicated below.

Besides the stabilized bleaching system which is the subject of the invention, there is at least one surfactant in the detergent composition, advantageously in an amount which can range from 8 to 20%, preferably of the order of 10 to 15%. the weight of said composition.

Among these surfactants, mention may be made of:

- anionic surfactants of the alkali metal soap type (alkaline salts of C ₈ -C ₂₄ fatty acids), alkali sulfonates (C ₈ -C ₁₃ alkylbenzene sulfonates, C ₁₂ -C ₁₆ alkyl sulfonates), alcohols C ₆ -C ₁₆ fatty oxyethylenated and sulfated, C ₈ -C ₁₃ alkylphenols oxyethylenated and sulfated, alkali sulfosuccinates (C ₁₂ -C ₁₆ alkyl sulfosuccinates) ... ₆ -C ₁₂ polyoxyethylenated, oxyethylenated C ₈ -C ₂₂ aliphatic alcohols, block copolymers of ethylene oxide - propylene oxide, optionally polyoxyethylenated carboxylic amides, - amphoteric surfactants of the alkyldimethylbetaine type,

- cationic surfactants of the chlorides or bromides of alkyltrimethylammonium, of alkylldimethylethylammonium. Various constituents can also be present in the detergent composition such as:

- "builders" of the type:

. phosphates and phosphonates, at a rate of 20 to 40% of the total weight of the formulation,. sodium silicate at a rate of 0.5 to 15% of the total weight of the formulation,

. zeolites at a rate of 10 to 25% of the total weight of the formulation,

. sodium carbonate in an amount of 5 to 15% of the total weight of the formulation, the total amount of "builder" corresponding to approximately 0.2 to 80%, preferably 20 to 45% of the total weight of said detergent composition.

It goes without saying that in the detergent composition, the cogranules used also exert the basic properties, in particular of the "builder" type for which they are known; these cogranules being used as percarbonate stabilizers in the compositions according to the invention, they are not included in the total amount of "builder" indicated above. anti-redeposition agents of the carboxymethylcellulose type, methylcellulose in an amount which can range up to approximately 5% of the total weight of said detergent composition, - anti-encrustation agents of the copolymer type of acrylic acid and maleic anhydride in an amount which can range up to approximately 10% of the total weight of said detergent composition,

fillers of the sodium sulfate type for detergents in powder in an amount which can range up to 50% of the total weight of said detergent composition.

The invention also relates to the use of a cogranule consisting of sodium or potassium carbonate, sodium or potassium silicate and water associated with silicate, the ratio (water associated with silicate) / (silicate expressed as dry) being of the order of 33/100 to 120/100, as stabilizing agent for a bleaching system at sodium or potassium percarbonate base.

For such use, the cogranule may also contain a siliconate and / or its derivatives, as described above.

The use of cogranules also makes it possible to stabilize a bleaching system based on sodium or potassium percarbonate activated by a bleach activating agent, such as TAED, PAG, TAGU, or ISONOBS.

The use of such carbonate-silicate cogranules as a stabilizing agent for percarbonate has the advantage of facilitating the preparation of the composition in so far as the stabilizer is a ready-to-use powder.

The invention therefore also relates to a process for the preparation of detergent compositions as described above by simple dry mixing of the constituents, for example by mixing on the one hand the bleaching system, optionally comprising the activator, and the stabilizing agent and, on the other hand, the other components.

The following examples illustrate the invention, without however limiting its scope.

The percentages discussed below are percentages by weight of the final detergent composition.

EXAMPLES 1 and 2

Detergent compositions with low addition of bleach activator (1.4%) are prepared in accordance with the invention. A cogranule manufactured and marketed by RHONE-POULENC under the brand Nabion 15 is used. It is made up of 29% sodium silicate, of Si0 ₂ / Na ₂ 0 ratio equal to 2, of 55% of sodium carbonate and 16% water. The water content associated with the silicate expressed by the weight ratio (water associated with the silicate) / (silicate expressed as dry) is 35%.

This cogranule is dry mixed with the TAED activator, sodium percarbonate and sodium sulfate to form mixtures A, the composition of which is shown in Table 1 below.

Comparative mixtures are prepared by substituting the co-granules of Nabion 15 with free sodium silicate and sodium carbonate in the proportions indicated in Table 1.

Mixtures A are subjected to a storage period of four months at an average temperature of 20 °

C, 60% relative humidity, in an enclosure that is not completely waterproof, reproducing storage in commercial laundry boxes.

To obtain the complete detergent compositions ready for the washing tests, the mixtures A are added to the same mixture B, the composition of which is as follows. Mixture B anionic surfactant (lab) 4.3 nonionic surfactants 8.6 zeolite 4A 17.9 sodium carbonate 10.7 sodium silicate, Rm 2, atomized 3.6

BASK SOKALAN CP5 * 3.6

Enzymes 0.2 carboxymethylcellulose 0.7 sodium sulfate 21.9. * BASK SOKALAN CP5 is a polyacrylate / ma- sodium leate.

The bleaching performance of the compositions is evaluated by simulated washing in a simplified machine of standardized soiled tissue test pieces, using a Tergotometer (US testing Company, Hobdoken, U.S.A.).

Washes are carried out in hard water at 25 ° TH French, at a washing temperature of 40 ° C, the concentration of use of the formulas being 7 g / liter. The performance is compared between the compositions before and after storage for four months.

Washing performance is estimated by measuring the difference in reflectance of the test pieces before and after washing (ΔR) and expressed in the form of a performance index which is the average of the measurements of ΔR over 2 times 8 test pieces, in 5 different points of the test pieces.

Tea and red wine stains have been used in particular because of their good reaction to the oxidation effects given by percarbonates and perborates. The results are reported in Table 1.

These results show that the compositions of Examples 1 and 2 containing cogranule retain their effectiveness better after aging of the powder than the compositions of Comparative Examples 1 and 2. This overall positive result on the conservation of the performance level is to be linked to the best conservation, in powder detergent, of oxidizing species active on soiling, in this case the stabilization of sodium percarbonate.

EXAMPLES 3 AND 4

The same tests were carried out with compositions with a high addition of TAED activator (2.9%). Table 2 provides a summary of the formulations and their performance.

These results likewise show that the compositions of Examples 3 and 4 retain their effectiveness better after storage than the compositions of Comparative Examples 3 and 4 containing no co-granules.

The stabilizing effect of the cogranules is more marked in the case of Examples 3 and 4 with a high level of TAED addition (2.9%) by comparison with Examples 1 and 2 with a low level of TAED addition (1, 4%). In addition, the stabilizing effect is more marked in the case of compositions with a low level of percarbonate (examples 2 and 4) in comparison with the compositions with a high level of percarbonate (examples 1 and 3). The good stabilization of systems activated by TAED, that is to say percarbonate-TAED couplings, makes the use of the cogranules according to the invention particularly advantageous in modern formulations of compact type and for washing at low temperatures.

Recall that the preparation of such compositions is very easy since there is no need to carry out a preliminary treatment to stabilize the percarbonate.

Claims

1. Powder detergent composition for washing clothes in a washing machine, containing a stable bleaching system based on sodium or potassium percarbonate, characterized in that it contains, as stabilizing agent for said percarbonate, a cogranule consisting of sodium or potassium silicate, sodium or potassium carbonate and water associated with silicate, the weight ratio (water associated with silicate) / (silicate expressed as dry) being from 33/100 to 120 / 100.

2. Composition according to claim 1 wherein the stabilizing agent of the percarbonate is a cogranule of sodium silicate and sodium carbonate, the molar ratio Si0 ₂ / Na ₂ 0 being from 1.6 to 3.5.

3. Composition according to claim 1, in which the cogranule further comprises a siliconate or one of its derivatives, the siliconate or its derivatives being products corresponding to the following formula (1):

R-Si (0M) _m (0H) ₃ _ _m (1)

and / or the condensation products thereof, formula in which R is a hydrocarbon residue of 1 to 18 carbon atoms, optionally substituted by an amino, ether, ester, epoxy, mercapto, cyano, polyglycol group; m is a number varying from 0.1 to 3; M is an alkali or alkaline earth metal or an ammonium or phosphonium group, the amount of siliconate or of its derivatives representing from 2 to 10% of the total weight of the cogranule.

4. Composition according to claim 3, in which the cogranule comprises sodium carbonate and sodium silicate, the molar ratio Si0 ₂ / Na ₂ 0 being from 1.6 to 3.5, and the siliconate is a methylsiliconate sodium or potassium.

5. Composition according to one of claims 1 to 4, wherein the cogranule is present in an amount of 8 to 22% by weight of the composition.

6. Composition according to claim 5, in which the cogranule is present in an amount of 12 to 18% by weight.

7. Composition according to one of claims 1 to 6, wherein the percarbonate is present in an amount of 6 to 20% by weight.

8. Composition according to claim 7, in which the percarbonate is present in an amount of 7 to 13% by weight.

9. Composition according to any one of claims 1 to 8, characterized in that the bleaching system further comprises a bleach activating agent.

10. The composition of claim 9, wherein the bleach activator is present in an amount of 0.5 to 6% by weight.

11. The composition of claim 10, wherein the activator is present in an amount of 1 to 5% by weight.

12. Use of a cogranule consisting of sodium or potassium silicate, sodium or potassium carbonate and water associated with silicate, the ratio (water associated with silicate) / (silicate expressed as dry) being 33 / 100 to 120/100, as stabilizing agent for a bleaching system based on sodium or potassium percarbonate.

13. Use according to claim 12 of cogranules of sodium silicate and sodium carbonate, the molar ratio Si0 ₂ / Na ₂ 0 being from 1.6 to 3.5.

14. Use according to claim 12 of a cogranule further comprising a siliconate or a of its derivatives, the siliconate or its derivatives being products corresponding to the following formula (1):

R-Si (OM) _m (OH) ₃ . _m (1),

and / or the condensation products thereof, formula in which R is a hydrocarbon residue of 1 to 18 carbon atoms, optionally substituted by an amino, ether, ester, epoxy, mercapto, cyano, polyglycol group; , m is a number varying from 0.1 to 3; M is an alkali or alkaline earth metal or an ammonium or phosphonium group, the amount of siliconate or of its derivatives representing from 2 to 10% of the total weight of the cogranule.

15. Use according to claim 14 of a cogranule comprising sodium carbonate and sodium silicate, the molar ratio Si0 ₂ / Na ₂ 0 being from 1.6 to 3.5, and the siliconate being a sodium methylsiliconate or potassium.

16. Use according to claims 12 to 15 of said co-granules for the stabilization of a bleaching system based on sodium or potassium percarbonate activated by a bleach activating agent.

17. Process for preparing a detergent composition according to claims 1 to 11, in which the bleaching system based on sodium or potassium percarbonate and the stabilizing agent is dry mixed and the other components are added by simple mixing dried up.