EP0075818B1 - Granular bleach activator - Google Patents

Description

The invention relates to granular bleach activators with a certain grain size for use in detergents or bleaches which contain water-swellable substances as auxiliaries and a process for the preparation of these activators.

It is known that detergents which contain per-compounds as bleaching agents are only successful with regard to their bleaching action at temperatures close to 100 ° C., because the per-compounds, mostly sodium perborate, do not yet decompose at lower temperatures with sufficient speed to be active in the To be able to intervene in the bleaching process. Therefore, so-called activators have been used for a long time, which reacted with the peroxo group of the per-compounds to form peracids, but the latter are already active at 30 to 60 ° C, i. H. at temperatures required for washing delicate textiles.

These activators, which include N- and O-acyl compounds, such as anhydrides or acid amides, and nitriles - a more detailed list is given below - are highly sensitive to hydrolysis, especially in the presence of detergents, which are common alkalis. This problem is exacerbated by the fact that the activators are often poorly soluble in water, which is why they had to be used in finely powdered form for faster dispersibility. It is precisely this finely divided form which, because of the enlarged surface, enables the activators to be hydrolysed during storage.

The most common way to shield bleach activators from moisture is to assemble them in the form of small particles, preferably coated with an auxiliary. Numerous methods for producing such particles and their use in detergents have been described in the literature.

In the majority of cases, an organic substance or a mixture of organic substances is used as a binding or coating agent, e.g. non-ionic surfactants, fatty acids, polymeric materials or waxes.

DE-A-26 57 042 discloses a detergent mixture which contains tetraacetylethylene diamine in the form of granulated particles. These particles consist e.g. B. from said activator and a smaller amount of a nonionic surfactant, which has a melting point of at least 35 ° C.

However, the use of organic substances has the disadvantage that it generally leads to handling problems, especially in the warm season, because of the stickiness, and furthermore the disadvantage that the dissolution or dispersion speed is often slow due to the increased disintegration time of the granules.

Inorganic substances have also already been used for the purpose in question.

For example, GB-A-1 360 427 teaches activator particles which are produced with granulation using sodium phosphate, and DE-A-28 55 777 granulates activator particles which are composed of a larger proportion of the activator itself and a small proportion of a hydratable salt mixture Combine sodium triphosphate and another salt. However, such granules still have insufficient properties. If they are not yet coated, their storage stability (hydrolysis) is unsatisfactory. The coating, on the other hand, limits the rapid dispersibility required in the wash liquor. In particular, the use of water as one of the auxiliary substances and the at least partial remaining water in the activator granulate made it very sensitive to temperature and hydrolysis.

The water bound in the crystal is z. B. released spontaneously when the transition point is exceeded and leads to the decomposition of the activator granules, as described in DE-A-28 55 777 on page 7. The use of readily water-soluble auxiliaries that have the properties of hydrated water is justified with the statement that this is the only way to achieve satisfactory rapid dispersion of the agglomerates under washing conditions.

Water-soluble cellulose ethers, starch and starch ethers are described as pelletizing aids for bleach activators in EP-A-0 037 026. As in DE-A-28 55 777, i.a. water used as an auxiliary for granulating. As in the first case, a small amount of water that has been brought in by the preparation remains in the granulate and immediately destroys part of the stabilization intended by the granulation process.

Every suitable method for assembling a bleach activator has two goals. On the one hand, there is an improvement in the hydrolysis stability of the activators, who, regardless of the chemical individual, all have an easily saponifiable active group that must be protected during storage in alkaline washing powder. Secondly, any suitable method for protecting the bleach activator from the environment must allow the activator to be rapidly dispersed in the wash liquor, i.e. The release of the activator in the finest distribution must take place within a period of time well before the end of the washing cycle so that the bleaching effect can be optimal.

The aim of the invention is to arrive at agglomerates composed of <300 μm particles without using water and without using highly water-soluble, highly hydratable compounds, which have the smallest possible inner surface from which no residual water has to be evaporated, and despite these parameters, previously known to be prohibitive for good dispersion, spontaneously disperse finely in the wash liquor and achieve a significantly better storage stability when stored compared to the prior art.

A further goal was a process which was as simple and economical as possible for producing such granular activators with a coarse particle size which corresponds to that of the other ingredients customary in dry detergents and which is generally 0.5 to 3 mm.

These objectives have been achieved with granular bleach activators of a certain composition and a process for their preparation as defined in claims 1 to 5 and 6, respectively.

The particles generally have a particle size of 0.5 to 3 mm, preferably 0.5 to 2 mm and are composed of 70 to 99.5, preferably 75 to 95% by weight of a bleach activator substance for per compounds and 0.5 to 30 , preferably 2.5 to 14% by weight of at least one water-swellable auxiliary. They preferably additionally contain 1 to 10, preferably 2.5 to 10% by weight of an inorganic or organic builder and / or dispersant; the sum of the percentages must of course be 100 each.

Bleach activators for per compounds are e.g. B. 0- and N-acylated compounds, such as pentaacetylglucose (PAG), pentapropionylglucose (PPG), tetraacetylethylenediamine (TAED), tetraacetylglycoluril (TAGU), carboxylic acid anhydrides such as succinic, benzoic or phthalic anhydride, or also salts, such as mixed sodium salts - or magnesium diacetyl phosphate (NA-DAP or MGDAP), and phenol esters such as p-carboxylphenylacetate, p-sulfonylphenylacetate, p-cresylacetate or phenylacetate.

In contrast to the previously used auxiliary substances, the water-swellable auxiliary substance is a substance that does not or only slowly dissolves in water at washing temperatures of at most 70 ° C, but only swellable, i.e. is able to absorb water with a large increase in volume. This clearly shows the function of the additive: The granules, which consist of a mixture of dust-fine microparticles of the activator substance and the additive, are torn apart under the influence of the water - it is therefore not a nonionic surfactant as an emulsifier or a readily soluble additive with a high hydrate water connection necessary for the dispersion of the particles.

The swellable excipient, because it acts as a “disintegrant”, causes immediate dispersion.

Auxiliaries in the sense of the invention are high-molecular carbohydrates such as starch, pulverized cellulose, wood pulp, as used in the paper industry, or cross-linked polyvinylpyrrolidone (PVP), which is known to be used in the pharmaceutical industry as a tablet disintegrant. It is preferred to use starch or the crosslinked PVP, but also starch ethers such as. B. carboxymethyl cellulose.

The builders and / or dispersants which are preferably additionally present for the purposes of the invention are inorganic, such as sodium sulfate, sodium carbonate, then preferably alkali or alkaline earth metal salts of phosphoric acid, oligomeric or polymeric phosphoric acids and organic, such as the alkali metal or edalkali metal salts of nitrilotriacetic acid, ethylenediaminetetraacetic acid, Polyacrylic acid, of copolymers of maleic acid with acrylic acid or vinyl ether and carboxymethyl cellulose. The organic acids mentioned can also be used in free form. Nitrilotriacetate, ethylenediamine triacetate, tripolyphosphate, maleic acid / acrylic acid copolymers as sodium salt and carboxymethyl cellulose (CMC) are particularly recommended as dispersants. Mixtures of the substances mentioned can also be used.

According to the invention, CMC can be used both as auxiliary b and as component c, d. H. the bleach activator can only contain CMC in addition to the activator substance. The amount of CMC is then to be measured in such a way that the defined percentages for components a and b are taken into account, i.e. In this case, the bleach activator contains 1.5 to 30% by weight of CMC, preferably 5 to 25% by weight.

The effect of the combination of activator, swellable auxiliaries and optionally builder and / or dispersant is additionally surprising insofar as addition of component c, which is both acidic and alkaline, leads to a significant increase in the storage stability of the compact. However, it is clearly evident from other studies that the hydrolysis of the activators is accelerated very strongly under acidic and in particular alkaline conditions.

The combination also results in a compact that is easily dispersed in the wash liquor within a few minutes. The particle size of the dispersed particles is in the same size arrangement; Surprisingly, the coarse proportion even drops significantly compared to that of the fine powder used in the compaction.

According to the invention, the granular activator is produced by compacting the mixture of the individual components.

The method of pelletizing or constructing granulation fails in this case because there is no binder and no water present, e.g. if the above-mentioned phosphates are used - they are sprayed onto the material to be granulated in aqueous solution - or if starch or cellulose ethers are used.

The production of the granular activator goes in detail, for. B in the way in front of him, that have first a definition according homogeneous mixture of the powdered excipient, the powdered activator and the powdered skeleton substance and / or dispersing agent, in which the activator particles generally have a particle size of about 10 _F to 300 lm, manufactures and this compacted. The compacting can be carried out in such a way that the aforementioned powder mixture is inserted into the gap of two whales rotating against each other by means of a stuffing screw Zen promotes and pressed between the rollers. The resulting band ("Schülpe") is broken on a shredder and limited to the desired grain size (0.5 to 3 mm) on a sieve shredder.

The material, the particle size of which lies outside the desired limits, is separated off and returned to the compactor together with another mixture to be compacted.

The resulting granular activator is surprisingly very stable in storage, as we have been able to determine, which could not be expected, since the insoluble and only water-swellable auxiliaries do not have any protective functions (coating) against the activator substances in the sense as described in the previous ones Publications should be the case. The storage stability, as we have also found, is in many cases even better, which was shown by the improved bleaching effect of the activators according to the invention which have been stored for a long time compared to activators of the prior art which have been stored for the same time. Even an increased activity can be achieved by adding component c.

The following examples and test results explain the invention insofar as the bleach activator is composed exclusively of components a and b.

Examples

Checking the storage stability of the granular activators

1) Preparation of the test washing powder

80 parts of a washing powder coming from a spray tower, to which perborate still has to be mixed, are mixed well with approx. 10 parts of TAED compactate = 8 parts of 100% TAED. The exact amount of compactate is determined from the TAED content of the compactate. If it contains less than 20% by weight of excipient, the amount of Na ₂ S0 _{4 which is} missing to 100% is additionally mixed.

The test washing powder has the following composition:

2) Carrying out storage tests

In each case 20 to 30 g of the washing powder mixture produced in this way are stored in open petri dishes in a climatic cabinet at 38 ° C. and 76% relative atmospheric humidity. The bleaching effect is determined immediately after mixing and after 21 and 42 days of storage.

A comparison is made with the bleaching effect of a powder mixture where the 10 g Na _z S0 _{4 contains} instead of the compact (no activation) and with the same washing powder mixture to which 8% of the compacted activator or an activator granulate according to the prior art is mixed before each bleaching attempt.

Since the powder is also subjected to storage wherever it is used, the low decomposition of the perborate has no influence on the relativized measurement results, which largely only indicate the hydrolysis of the activator.

3) Testing the bleaching effect of the test washing powder

• Prüfgerät: Launder-Ometer
• Wasserhärte: 16°dH
• Flottenmenge: 250 ml
• Flottenverhältnis: 1:12,5
• Waschmittelkonzentration: 7 g/I

a) Test conditions:

• Tester: Launder-Ometer
• Water hardness: 16 ° dH
• Amount of liquor: 250 ml
• Fleet ratio: 1: 12.5
• Detergent concentration: 7 g / l

• 10g Baumwollnessel roh (Weissgrad ca. 59%)
• 5g gebleichter Baumwollnessel mit Rotweinanschmutzung (Weissgrad ca. 70%)
• 5g gebleichter Baumwollnessel mit Teeanschmutzung (Weissgrad ca. 54%)

b) Test fabric:

• 10g raw cotton nettle (whiteness approx. 59%)
• 5g bleached cotton nettle with red wine soiling (whiteness approx. 70%)
• 5g bleached cotton nettle with tea stain (whiteness approx. 54%)

The three different test fabrics each washed for 30 minutes at room temperature, 25 to 45 ° C and 35 to 60 ° C give 9 values after whiteness measurement, which are added up. Through this accumulation and through double determination, the values achieve a sufficient degree of reliability.

The degrees of whiteness were measured with the Zeiss ELREPHO device with filter 8, xenon lamp with FL 46.

The difference between the sums of the white degrees of Wioo (see below) and Wo, multiplied by 100, corresponds to the activation of the undecomposed activator (100%). The difference in the whiteness sums of W _x and Wo, divided by the difference in the whiteness sums of W ₁₀₀ and Wo, multiplied by 100 gives the activity of the powder W _x remaining after storage in percent.

In each case 80 parts of the washing powder coming from the spray tower and 10 parts of sodium perborate were mixed with the respective activator mentioned below in such a way that a content of 8 parts of tetraacetylethylenediamine (TAED) was obtained in the powder. Possibly missing additional quantities were added to 100 parts with Na ₂ S0 ₄ .

• Wo = Waschpulver ohne Aktivator (nur Na₂S0₄)
• W₁₀₀ = Waschpulver + kristalline TAED (8%) zugesetzt vor jedem Bleichversuch
• W₃ = Waschpulver + 8% TAED kompaktiert mit 5% Maisstärke - bezogen auf TAED-, Korngrösse 2mm
• W₄ = Waschpulver M₃, TAED-Kompaktat zusätzlich überzogen mit 4% 25-fach ethoxyliertem Fettalkohol
• W₅ = Waschpulver M₃, TAED-Kompaktat zusätzlich überzogen mit 8% 25-fach ethoxyliertem Fettalkohol
• W₆ = Waschpulver + 8% TAED kompaktiert mit 5% vernetztem Polyvinylpyrrolidon - bezogen auf TAED
• W₇ = Waschpulver + 8% TAED kompaktiert mit 3% Maisstärke - bezogen auf TAED - Korngrösse 0,8-1,5 mm
• W₈ = Waschpulver + 8% TAED kompaktiert mit 10% Maisstärke - bezogen auf TAED
• Wg = Waschpulver + 8% TAED kompaktiert mit 5% Hydroxymethylcellulose
• W_lo = Waschpulver + 8% TAED granuliert gemäss DE-A-28 55 777, Beispiel 1
• W₁₁ = Waschpulver + 8% kristallines nicht kompaktiertes TAED

Mean it

• Wo = washing powder without activator (only Na ₂ S0 ₄ )
• W ₁₀₀ = washing powder + crystalline TAED (8%) added before each bleaching test
• W ₃ = washing powder + 8% TAED compacted with 5% corn starch - based on TAED, grain size 2mm
• W ₄ = washing powder M ₃ , TAED compactate additionally coated with 4% 25-fold ethoxylated fatty alcohol
• W ₅ = washing powder M ₃ , TAED compactate additionally coated with 8% 25-fold ethoxylated fatty alcohol
• W ₆ = washing powder + 8% TAED compacted with 5% cross-linked polyvinylpyrrolidone - based on TAED
• W ₇ = washing powder + 8% TAED compacted with 3% corn starch - based on TAED - grain size 0.8-1.5 mm
• W ₈ = washing powder + 8% TAED compacted with 10% corn starch - based on TAED
• Wg = washing powder + 8% TAED compacted with 5% hydroxymethyl cellulose
• W _lo = washing powder + 8% TAED granulated according to DE-A-28 55 777, example 1
• W ₁₁ = washing powder + 8% crystalline non-compacted TAED

The bleaching results are shown in Table I below. In this example 1-11 relate to the washing powder Wo, W ₁₀₀ , W3, W ₄ ... W ₁₁ .

The following examples explain the preferred combination of three from a), b) and c).

Checking the storage stability of the granular activators

1. Preparation of the test washing powder

A test washing powder is made by mixing a tower powder with 10% perborate and so much made-up cold bleach activator that 8% activator is 100% contained in the detergent. Make up to 100% detergent with 33% sodium sulfate. When using ready-made cold bleach activator, the dispersant is offset against the 33% sodium sulfate.

After mixing, the test washing powder has the following composition:

2. Carrying out the storage tests

30 g of the washing powder mixtures W _x thus produced are stored in open petri dishes in a climate controlled cabinet at 40 ° C. and 76% relative atmospheric humidity.

The bleaching effect is determined immediately after mixing and after 21, 42 and 84 days of storage.

A comparison is made with the bleaching effect of a powder mixture Wo which contains Na ₂ S0 ₄ instead of the cold bleach activator (no activation) and with the same washing powder mixture which 8% crystalline activator is freshly added before each bleaching attempt (W ₁₀₀ ) (experiments 28 and 29).

Since the powder is also subjected to storage wherever it is used, the low decomposition of the perborate has no influence on the relativized measurement results, which largely only indicate the hydrolysis of the activator.

3. Testing the bleaching effect of the test washing powder

• Prüfgerät: Launder-Ometer
• Wasserhärte: 16°dH
• Flottenmenge: 250 ml
• Flottenverhältnis: 1:12,5
• Waschmittelkonzentration: 7 g/l

a) Test conditions:

• Tester: Launder-Ometer
• Water hardness: 16 ° dH
• Amount of liquor: 250 ml
• Fleet ratio: 1: 12.5
• Detergent concentration: 7 g / l

• 10g Baumwollnessel roh (Weissgrad ca. 59%)
• 5g gebleichter Baumwollnessel mit Rotweinanschmutzung (Weissgrad ca. 70%)
• 5g gebleichter Baumwollnessel mit Teeanschmutzung (Weissgrad ca. 54%)

b) Test fabric:

• 10g raw cotton nettle (whiteness approx. 59%)
• 5g bleached cotton nettle with red wine soiling (whiteness approx. 70%)
• 5g bleached cotton nettle with tea stain (whiteness approx. 54%)

The three different test fabrics each washed for 30 min at room temperature, 25 to 45 ° C and 35 to 60 ° C give 9 values after whiteness measurement, which are added up. Through this accumulation and through double determination, the values achieve a sufficient degree of reliability.

The degrees of whiteness were measured with the Zeiss ELREPHO device with filter 8, xenon lamp with FL 46.

ΣW_x soll dabei die Summe der Weissgrade der Waschmittelmischung W_x sein, ΣW_o und ΣW₁₀₀ sind die Summen der Weissgrade der beiden vorher beschriebenen Mischungen mit der Aktivierung Null und 100%.The difference in the sums of whiteness from W ₁₀₀ and Wo corresponds to 100% activation. The Activation in% of a mixture is calculated using the following formula

ΣW _x should be the sum of the degrees of whiteness of the detergent mixture W _x , ΣW _o and ΣW ₁₀₀ are the sums of the degrees of whiteness of the two previously described mixtures with zero and 100% activation.

Example 12

A mixture of 90 parts of tetraacetylethylene diamine (TAED) with a special particle size distribution1, 5 parts of corn starch and 5 parts of sodium tripolyphosphate is homogenized in a continuously running Lödige mixer, fed to a roller press by means of a feed screw and compacted into flakes. The scoop is crushed in a hammer mill. Subsequent fractionation leads to a useful fraction with a particle size between 0.5 and 2 mm in diameter. Oversize and undersize granules are used for grinding or compacting.

• 90 Teile TAED
• 5 Teile Maisstärke
• 5 Teile Natriumtripolyphosphat,
  

A granulate of the composition is obtained:

• 90 parts TAED
• 5 parts of cornstarch
• 5 parts of sodium tripolyphosphate,
  

which is added together with sodium perborate and optionally sodium sulfate to a so-called tower powder in such a way that a washing powder is formed which has the composition described at the beginning.

Analogous to Example 12, analog compactings were carried out with different amounts of auxiliaries and additives. The product composition is shown in Examples 13 to 25 below (Table II).

The grit granules described in Examples 12 to 25 were then incorporated into a test washing powder in accordance with the test method described and tested for their activating effect. As a result, the washing results were evaluated in the degree of whiteness of the different soiled fabrics washed at different temperatures. The whiteness which was obtained with a detergent (tower powder + perborate) + TAED, example 28 and PAG, example 29 was evaluated as 100% whiteness. The% activation after storage was calculated according to the formula given above.

Activation values in% based on the initial value (no storage) after 21 days, 42 days and 84 days of storage of the washing powder + activator.

It is important for successful bleaching that the bleach activator is quickly dispersed in the bleach.

Coarse cold bleach activators have a surface that is too small, moreover they can lead to fiber damage together with perborate even in unfavorable cases if they are deposited in the laundry. For all these reasons, the spontaneous dispersion of the agglomerates, be they mixer granules or compactates, in the wash liquor is required.

Since the compacts are produced under high roller pressure, whereas mixed granules are only agglomerated, there was reason to fear that compactates would be significantly inferior to the mixed granules in terms of dispersion in the wash liquor.

Surprisingly, the compactates described here behave just as favorably as the mixer granules when dispersing. They even have an advantage. The bulk of the output activator, which has> 200flm diameter, is still crushed by the compacting, i. H. it is decreasing.

Table IV shows the dispersion times and the particle size distribution of some examples.

Claims (6)

1. A granular bleaching activator for use in a detergent or bleach, which has particles which have a size of from 0,5 to 3 mm and are composed of

a) from 70 to 99,5% by weight of one or more bleaching activators for per-compounds, and

b) from 0,5 to 30% by weight of one or more water-swellable assistants

and which habe been prepared, without use of water, by compacting the components a) and b).

2. A granular bleaching activator as claimed in claim 1, which additionally contains

c) from 1 to 10% by weight of one or more inorganic or organic builders and/or dispersants, co-compacted with components a and b, the sum of the percentages of a, b and c being 100.

3. A bleaching activator as claimed in claim 1 or 2, wherein the particles are composed of from 75 to 95% by weight of the bleaching activator substance, from 2,5 to 15% by weight of the assistant and from 2,5 to 10% by weight of the builder and/ or dispersant.

4. A bleaching activator as claimed in claims 1 to 3, wherein the assistant b is crosslinked polyvinyl-pyrrolidone or a high molecular weight carbohydrate.

5. A bleaching activator as claimed in claims 1 to 4, wherein component c is an alkali metal salt or alkaline earth metal salt of phosphoric acid, oligomeric phosphoric acid or polymeric phosphoric acid, an alkali metal salt of alkaline earth metal salt of nitrilotriacetic acid, of ethylenediaminetetraacetic acid, of polyacrylic acid or of a maleic acid/acrylic acid or maleic acid/vinyl ether copolymer, or ist one of the said organic acids in the free form, or is carbopxymethylcel- lulose.

6. A process for the preparation of a granular bleaching activator as claimed in claims 1 to 5, wherein from 70 to 99,5 parts by weight of a bleaching activator substance for per-compounds and from 0,5 to 30 parts by weight of a waterswell- able assistant, with or without from 1 to 10 parts by weight of an inorganic or organic builder and/ or dispersant, the sum of the parts by weight being 100 and each component being in pulverized form, are mixed homogeneously, without using water as an assistant, the mixture is compacted, the compacted material is then comminuted, and the fractions with a particle size of from 0,5 to 3 mm are separated off in a manner known per se.