EP0618960B1 - Bleach activators in granular form (ii) - Google Patents

Abstract

The description relates to a pourable granulate, the main constituent of which are bleach activators for washing textiles in the form of a finely dispersed solid phase embedded in a virtually waterless phase penetrating the granulate grain and acting as a binder, said phase being essentially composed of solid matters. This binder phase consists of a homogenised mixture of anionic tensides and solubility enhancers in mutually adjusted proportions such that, at the working temperature for granulate formation, the binder mixing phase becomes liquid or plastic even without the addition of water. The bleach activator granulates may be obtained by premixing the finely divided bleach activators with the components of the binder and with other additives if required, homogenising the mixture of substances, preferably at moderately raised temperatures, to form a compressible mass and extruding it under high pressure into a strand, cutting the strand to the required grain form and rounding it if necessary.

Description

The invention relates to new pourable and free-flowing granules which contain bleach activators for textile washing embedded in a binder phase as the main component, the binder phase containing surfactants which are solid at room temperature and moderately elevated temperatures. The invention further relates to a method for producing these new bleach activator granules.

Inorganic peroxy compounds that dissolve in water releasing hydrogen peroxide, such as sodium perborate and sodium percarbonate, have long been used as oxidizing agents for disinfection and bleaching purposes. The oxidizing effect of these substances in dilute solutions depends strongly on the temperature. With perborate in alkaline bleaching liquors, sufficiently quick bleaching of soiled textiles can only be achieved at temperatures above 60 ° C. At lower temperatures, the oxidation effect of the inorganic per-compounds can be improved by adding activators, for which numerous proposals have become known in the literature. The addition of these activators can increase the bleaching effect of aqueous peroxide liquors to such an extent that they are already active in the temperature range from 30 to 60 ° C., ie. H. at temperatures required for washing delicate textiles.

However, these activators, for example from the class of the N- and O-acyl compounds, are highly sensitive to hydrolysis, especially in the presence of the alkalis which are generally customary in detergents. The problems derived from this for the storage stability of the textile detergents are exacerbated by the fact that the activators are often poorly soluble in water, so that finely powdered materials with rapid dispersibility should be used. This very finely divided form allows due to increased surface area the increased hydrolysis of the activators during their storage.

To remedy this, practice provides for the bleach activator component in the form of separately produced granules to be added to the dry washing or cleaning agent mixtures, the agglomerates of very fine bleaching agent particles being coated with auxiliaries. A wide variety of organic and inorganic substances have been proposed as granulation aids and coating materials for such activator granules. In particular, it is known to use surfactant compounds from the classes of anionic, cationic and / or nonionic surfactants, polymeric materials or waxes which are solid at room temperature. With regard to details of the prior art, reference is made to the older, unpublished German patent application P 40 24 759.7, which also relates to bleach activators in the form of granules.

The subject of US Pat. No. 4,486,327 and the earlier German application P 40 24 759.7 are granules in which the finely divided bleach activator is embedded in a practically anhydrous phase which serves as a binder and consists of a mixture of anionic and nonionic surfactant compounds, these granules being produced by extrusion of the plasticized one Mixture can be produced at elevated temperature. Depending on the quality of the nonionic surfactant used, these granules have either proven to be too slowly soluble at low temperatures or they were so brittle that an unacceptably high proportion of fine-grained material was obtained when the granules were rounded off.

The object of the present invention was therefore to avoid the above-mentioned disadvantages of the previous granules, without giving up their advantages, in particular the high storage stability and the ease of manufacture.

This problem was solved by special selection of the components serving as binders so that the manufacturing process could otherwise be retained.

The invention relates to a pourable and free-flowing granulate which contains bleach activators for textile washing as a finely dispersed solid phase as the main constituent, embedded in a practically anhydrous phase penetrating the granulate grain and serving as a binder, and which is obtained by extrusion of a practically water-free mixture of bleach activator, anionic surfactant, solubilizing aid and optionally further additives are produced, characterized in that the solubilization aid is selected from the group consisting of polyethylene glycol, polypropylene glycol, anionically modified polyethylene glycol on one or both hydroxyl groups, anionically modified polypropylene glycol on one or both hydroxyl groups, and mixtures of these compounds.

Another object of the invention is a process for the production of the granules, in which the finely divided bleach activator is premixed with the other components, the mixture of substances is homogenized at a preferably elevated temperature to form an extrudable mass and extruded in the form of a strand using increased pressure, the emerging strands, if appropriate after cooling, cuts into short pieces and rounds off these pieces if necessary and, if desired, classified according to size.

What is essential to the teaching of the invention is the joint use of anionic surfactants and solubilization aids in the bleach activator granules. Both components together can take on binder functions and envelope functions and can be selected so that the mixture of all the granulate components takes on plastic properties at room temperature or only moderately elevated temperature and can be extruded in the form of a strand. Despite this property, the granules obtained are not tacky at the temperatures to which they are usually exposed during later storage and remain free-flowing. At the same time, the use of the above-mentioned components as binders achieves high storage stability, especially in a humid atmosphere and in the presence of other detergent components.

The mixture of anionic surfactant and solubilizing aid which serves as the binder is preferably selected so that this mixture only softens at temperatures above the highest usual storage temperatures, ie above temperatures of about 35 to 40 ° C. The granulation then takes place in the temperature range above, and if temperature-sensitive bleach activators or granulate components are used, corresponding upper limit temperatures must be observed. Preferably the working temperatures during the granulation are not above 90 ° C., in particular not above 80 ° C., whereby working temperatures in the range from about 45 to 75 ° C. may be particularly suitable.

According to the invention, it may be preferred to choose the anionic surfactant component as the larger proportion in the binder mixture. It is particularly preferred here to use corresponding anionic surfactant compounds which are solid at room temperature and granulate formation temperature and which can make up at least 55% by weight and up to 98% by weight of the binder mixture. In an expedient embodiment, the anionic surfactant content is in the range from 60 to 95% by weight, in particular 60 to 85% by weight, based on the weight of the binder mixture. Based on the total weight of the granulate, the proportion is preferably 4 to 25% by weight, in particular 6 to 15% by weight.

Suitable solid anionic surfactants are the solid components known in detergent technology, in particular in the context of textile detergents, which belong in particular to the following classes of substances: alkyl sulfates, alkyl sulfonates, alkylarylsulfonates, sulfonated fatty acid esters and / or soaps. Particularly suitable anionic surfactants are, for example, C ₁₂ -C ₁₈ fatty alcohol sulfates, which can be present individually or in a mixture, such as lauryl sulfate, myristyl sulfate and here in particular C ₁₆ -C ₁₈ tallow alcohol sulfate. Other suitable special anionic surfactant components are alkylbenzenesulfonates (ABS) with 9 to 13 carbon atoms in the alkyl chain, in particular C ₁₂ alkylbenzenesulfonate, wash-active salts of alpha-sulfonated fatty acid methyl esters and / or sodium soaps of fatty acids, in particular of fatty acids with 12 to 18 carbon atoms . The salts of long-chain ester carboxylic acids, such as those obtainable from fatty alcohols having 8 to 18 carbon atoms and di- or polycarboxylic acids, for example maleic anhydride or citric acid, may also be suitable. The anionic surfactants are preferably used in the form of the sodium salts. The use of unsaturated components and / or the use of potassium soaps can influence the plasticizability of the binder mixture at the elevated working temperatures.

The compounds used as solubilization aids according to the invention are polyethylene and / or polypropylene glycols or derivatives of these compounds. The average molecular weight of these polymers is preferably in the range between about 200 and about 12,000. Polyethylene glycols with an average molecular weight between 600 and 4,000 are particularly preferred. The derivatives of the polyalkylene glycols which are suitable according to the invention are polymers which have one or both terminal hydroxyl groups are anionically modified. The sulfates and / or in particular the disulfates of the abovementioned polyalkylene glycols are suitable. The sulfosuccinates and / or disulfosuccinates of these polyalkylene glycols are also suitable. These anionic derivatives are preferably derived from polyglycols with average molecular weights between 600 and 6000, in particular from those with average molecular weights between 1000 and 4000. The anionic derivatives can be present as salts of any cations, but are preferably used as alkali salts, in particular as sodium or potassium salts, and as salts of organic amines, for example triethanolamine.

Mixtures of the polyalkylene glycol ethers and their anionically modified derivatives are preferably also used in any mixing ratio. In particular, a mixture of polyalkylene glycol and the sulfosuccinates and / or disulfosuccinates of the polyalkylene glycols is preferred. However, a mixture of polyalkylene glycol and the corresponding sulfates and / or disulfates and a mixture of polyalkylene glycol, the corresponding sulfates and / or disulfates and the corresponding sulfosuccinates and / or disulfosuccinates are also suitable. The proportion of the solubilization aid in the granulate is preferably 0.5 to 15% by weight, in particular 1 to 6% by weight.

In the most important embodiment according to the invention, mixtures of anionic surfactant and solubilizing aids are used as binders which are highly effective plasticizers at the working temperature of the granulation, so that the desired plasticized good quality can be set with limited amounts of the binder. In this embodiment, the amounts of binder are preferably below about 50% by weight of the total mixture, and the bleach activator is preferably present in this total mixture in amounts of about 70 to 95% by weight. Particularly suitable activator contents can range from about 75 to 90% by weight on the entire granulate. The rest of the granulate is formed by the binder or at least to a substantial extent by this surfactant binder. In important embodiments, the granules contain at least about 3% by weight, preferably at least about 5% by weight, of the binder mixture, based in each case on the entire granulate, binder amounts in the range from about 7 to 25% by weight being particularly preferred can.

The free-flowing, practically water-free compactates that directly occur in the process can contain as bleach activators all substances or substance mixtures known today for this purpose. For the sake of completeness, the substances are summarized again as follows: Accordingly, suitable bleach activators for per-compounds are 0- and / or N-acylated compounds such as pentaacetylglucose (PAG), pentapropionylglucose (PPG), tetraacetylethylenediamine (TAED), tetraacetylglycoluril (TAGUanol, triacetylamine) TAEA), acylated triazine derivatives such as 1,5-diacetyl-2,4-dioxohexahydro-1,3,5-triazine (DADHT), carboxylic anhydrides such as succinic, benzoic or phthalic anhydride, salts of mixed anhydrides such as sodium or magnesium diacetyl phosphate ( NADAP or MGDAP), phenol esters such as p-carboxylphenylacetate, p-sulfonylphenylacetate, and further phenol esters with an anionic substituent on the phenyl radical. In a particular embodiment, the process according to the invention for producing the bleach activator granules is characterized in that the multicomponent mixture is first mixed as uniformly as possible in a suitable mixing device in the region of room temperature or only moderately elevated temperatures. All customary devices, for example of the Lödige ploughshare mixer type, are suitable as the mixing device. This premix is then fed to the homogenization and extrusion stage. Although basically any homogenizing and extrusion devices - for example linear screw extruders - are suitable, a processing device has proven to be particularly suitable for carrying out the method according to the invention. This is the extrusion by means of a pellet press. It can be useful to work in devices of this type with a temperable roller (press roller), as described in detail in DE 38 16 842 are. The temperature of the material in the working space of the pellet press can be set to predetermined values by means of this temperable pan, the aforementioned temperature range up to a maximum of 90 ° C. and preferably from 45 to 70 ° C. being selected here.

If necessary, the cut granulate is subjected to shock cooling. Air or cooled air can be used as the cooling medium. Additionally or alternatively, the primarily extruded and cut granulate can be superficially loaded with particulate solids. Examples include powdered zeolites, especially detergent grade zeolite NaA, talc, silica and the like.

It may be desirable or expedient to incorporate further auxiliaries or additives into the granulate in addition to the finely divided solid bleach activators and the binder. The proportion of these additives is preferably not more than 10% by weight, based on the granules.

Particularly noteworthy in this context are finely divided, readily soluble alkali salts of inorganic or organic acids. The addition of these substances can in individual cases further accelerate the release of the activator when the granules are introduced into water. Particularly suitable salts are sodium carbonate, sodium sulfate and sodium citrate. The proportion of these salts in the granules is preferably not more than 10% by weight, based on the total weight of the granules, in particular it is between about 0.5% by weight and about 5% by weight.

Other additives which may be used are, for example, dyes as are customary in the detergent sector. To incorporate these substances, it may be appropriate to suspend or dissolve them in liquid granulate components before they are mixed in. Preferred dyes are pigment dyes, such as copper phthalocyanine dyes. For better distribution of the dye in the granules, it may be advantageous to disperse the dye in small amounts of water before the addition. The amount of water should not be more than 1% by weight, preferably not more than 0.5% by weight, based on the total weight of the granules. Examples of other suitable auxiliaries are disintegrants and lubricants.

During the extrusion of the multicomponent mixture brought to working temperature, compression ratios can be set such that the finished granules have bulk densities of at least 500 g / l. Bulk weights in the range up to 1000 g / l are particularly suitable, bulk densities in the range 600 to 900 g / l being preferred. By choosing the respectively specified extrusion pressures and other processing conditions, depending on the material properties of the multi-component mixture, practically every density range desired in the individual granules can be set in a targeted manner.

Preferred granules are either cylindrical or spherical. The additional rounding of the cylindrical shapes can expediently take place immediately after cutting to length on the still sufficiently warm granulate. Auxiliary devices suitable for rounding off are known, for example the Marumerizers used for this purpose.

The grain size of the granules is regulated in a manner known per se and is expediently set in the range from 0.7 to 3 mm. For example, the granules can be cut to the desired grain length of 0.7 to 3 mm or beyond, for example to a grain length of 5 mm. These cylindrical granules with lengths above 3 mm are then broken to a predetermined length and rounded if necessary so that a length of 3 mm is not exceeded. Cylindrical granules preferably have a length of up to 2 mm, while additionally rounded, preferably spherical granules have a particle diameter in the range from 0.4 mm to 1.6 mm.

Examples

To produce the granular bleach activators, the respective constituents were mixed intensively for one minute in a ploughshare mixer (Lödige, Germany) in the mixing ratios shown in the table. The premix obtained in this way was then fed continuously to a ring die press (pellet press, embodiment according to DE 38 16 842, Schlüter, Germany), the temperature-controlled roller (press roll) of which was heated to 50.degree. During the implementation of the process, there were slight temperature fluctuations, the temperature of the press roll not dropping below 45 ° C. and not rising above 60 ° C. The diameter of the press channels with which the ring die was penetrated was 1.2 mm. The distance between the press roller and the ring die was 1.5 mm. The emerging strand was cut to a length of 1.5 mm by a knife attached to the outside of the ring die. The bulk weights of the granules were between 630 and 700 g / l. The cut-to-length granules were then rounded off in a Marumerizer-type rounding machine. The proportion of good grain (sieve fraction between 0.4 and 1.6 mm) of the granules decreased only slightly.

To determine the dissolving speed of the granules, 0.5 g of the rounded and sieved granules were stirred in 1 liter of water (17 ° German hardness) at 40 ° C. in a beaker for 5 minutes with a paddle stirrer at 700 revolutions per minute. After this time, the entire contents were filtered through a metal sieve with a mesh size of 0.1 mm and the sieve with the residue was dried to constant weight at room temperature. The amount of the residue is given in the table in% based on the weight of granules. The solubility was determined on the one hand on freshly prepared granules and on the other hand on such granules which had been stored at 40 ° C. for 5 days.

From the values given in the table, the advantageous properties of the granules 1 to 6 according to the invention compared to the granules 7 to 12 produced analogously to the earlier application DE P 40 24 759.7 can be clearly seen. (EO in the table means ethylene oxide.)

Claims (10)

1. Pourable and free-flowing granules which contain as their principal component bleach activators for the washing of laundry embedded as a finely dispersed solid phase in a substantially water-free phase permeating the granules and serving as binder and which are produced by extrusion of a substantially water-free mixture of bleach activator, anionic surfactant, solubilizing aid and optionally other additives, characterized in that the solubilizing aid is selected from the group consisting of polyethylene glycol, polypropylene glycol, polyethylene glycol anionically modified at one or both hydroxyl groups, polypropylene glycol anionically modified at one or both hydroxyl groups and mixtures of these compounds.
2. Granules as claimed in claim 1 containing water-soluble alkali metal salt as a further additive.
3. Granules as claimed in claim 1 or 2 containing

   70 to 95% by weight of bleach activator

   4 to 25% by weight of anionic surfactant

   0.5 to 15% by weight of solubilizing aid

   0 to 10% by weight of alkali metal salt.
4. Granules as claimed in claim 3 containing

   75 to 90% by weight of bleach activator

   6 to 15% by weight of anionic surfactant

   1 to 6% by weight of solubilizing aid

   0.5 to 5% by weight of alkali metal salt.
5. Granules as claimed in claim 1 or 2 in which the bleach activator is selected from the group consisting of pentaacetyl glucose, tetraacetyl ethylenediamine, 1,5-diacetyl-2,4-dioxohexahydro-1,3,5-triazine and mixtures thereof.
6. Granules as claimed in claim 1 or 2, in which the anionic surfactant is selected from the group consisting of C_12-18 fatty alcohol sulfates, alkylbenzenesulfonates containing 9 to 13 carbon atoms in the alkyl chain, α-sulfofatty acid methyl esters containing 12 to 18 carbon atoms in the carboxylic acid component and mixtures thereof.
7. Granules as claimed in claim 1 or 2, in which the solubilizing aid is selected from the group consisting of polyethylene glycol, polypropylene glycol, sulfates and/or disulfates of polyethylene glycol or polypropylene glycol, sulfosuccinates and/or disulfosuccinates of polyethylene glycol or polypropylene glycol and mixtures thereof.
8. Granules as claimed in claim 2, in which the alkali metal salt is selected from the group consisting of sodium carbonate, sodium sulfate, sodium citrate and mixtures thereof.
9. A process for the production of the bleach activator granules claimed in claim 1, in which the fine-particle bleach activator is mixed with the other components, the resulting mixture is homogenized, preferably at elevated temperature, to form a paste extrudable in strand form and the paste obtained is extruded in strand form under elevated pressure, the issuing strands are cut into short pieces, optionally after cooling, and the pieces obtained are optionally spheronized and, if desired, graded according to size.
10. A process as claimed in claim 9, in which the working temperature is allowed to rise to a value of at most 80°C and preferably to a value of about 45 to 75°C.