EP0571436B1 - Granular additive for washing and cleaning agents - Google Patents

Abstract

The granular additive disclosed, which may be used to pretreat hard water or employed together with washing and cleaning agents, contains 40-75 % by wt. of the sodium salts of at least one homopolymer or copolymer of methacrylic acid, 1-35 % by wt. of a finely crystalline synthetic zeolite containing bound water, 2-20 % by wt. of sodium sulphate (calculated as the anhydrous salt) and 1-15 % by wt. of water. The granulate initially produced preferably by spray drying is compacted under the action of pressure to give a granulate with a bulk density between 500 and 900 g/l, without affecting the free-running or storage characteristics of the granulate.

Description

The invention relates to a granular additive for detergents and cleaning agents and to a method for producing these additives.

Due to its good lime binding properties, it can be used as an additive to wash water in hard water areas or for the pretreatment of hard water intended for washing, rinsing and cleaning purposes. The additives are usually stored separately from granular detergents and cleaning agents and, if required, used together with these in washing or cleaning processes. In the sense of an additional builder effect, they improve the cleaning ability of the actual washing and cleaning agent and prevent the formation of hard limescale deposits on the heating elements or on the textile fiber. In special cases, the detergents can be added to granular detergents and cleaning agents or processed together with them, thereby advantageously influencing their pouring properties and washing-in behavior or enabling trouble-free further processing.

Known agents of this type often contain salts of polymeric aliphatic carboxylic acids. These include, in particular, salts of polyacrylic acid and polymethacrylic acid and salts of copolymers of these two acids with maleic acid and / or vinyl esters. There are no difficulties in producing storage-stable granules which contain up to about 15% by weight of such polymer salts. However, since the salts of the polymeric polycarboxylates are hygroscopic, mixtures with higher proportions of such salts cannot readily be converted into storage-stable and free-flowing granules, especially not if they do not contain any water-binding or water-repellent mixture components.

To solve this problem, German patent application 21 00 500 (Unilever) proposes to use the polymers as free acids or partially neutralized salts with a degree of neutralization of at most 60% or to convert them from their aqueous solutions into granular products by hot spray drying. Agents that contained a higher proportion of neutralized salts showed under after only one week of storage Room temperature conditions a strong softening. However, the polymeric carboxylic acids only develop their full effect as completely neutralized salts. The alkaline agent required for neutralization must therefore be subsequently added to the acidic granules.

German patent application 36 04 223 discloses granular additives for detergents and cleaning agents which contain 20 to 80% by weight of homo- or copolymeric (meth) acrylic acids or, if appropriate, their water-soluble salts. The problem of the hygroscopicity of such concentrated agents could be solved by the agents additionally containing 20 to 80% by weight of nitrilotriacetic acid (NTA) or salts thereof. Other components of detergents and cleaning agents, for example sodium sulfate and / or sodium aluminum silicates, can additionally be present in the agents up to 20% by weight.

It has now surprisingly been found that defined salt mixtures can be produced with a comparatively high content of completely neutralized salts of polymeric carboxylic acids which are storage-stable and free-flowing as granules.

The invention relates to a granular additive that
40 to 75% by weight of sodium salts of at least one homopolymeric or copolymeric (meth) acrylic acid,
1 to 35% by weight of synthetic, finely crystalline, zeolite containing bound water,
2 to 20 wt .-% sodium sulfate (calculated anhydrous) and
1 to 15 wt .-% water, but contains no nitrilotriacetic acid or sodium or potassium salts of nitrilotriacetic acid.

Suitable homopolymers are sodium salts of polymethacrylic acid and preferably polyacrylic acid, for example those with a relative molecular weight of 800 to 150,000 (based on acids). If only homopolymeric polyacrylic acids (in salt form) are used, their relative molecular mass is preferably 1,000 to 80,000 (based on acid) in the interest of good flowability and storage stability.

Suitable copolymers are those of acrylic acid with methacrylic acid and preferably copolymers of acrylic acid or methacrylic acid with maleic acid. Copolymers of acrylic acid with maleic acid which contain 50 to 90% by weight of acrylic acid and 50 to 10% by weight of maleic acid have proven to be particularly suitable. Copolymers in which 60 to 85% by weight of acrylic acid and 40 to 15% by weight of maleic acid are present are particularly preferred. Their relative molecular weight, based on free acids, is generally 5,000 to 200,000, preferably 10,000 to 120,000 and in particular 50,000 to 100,000.

Mixtures of different homo- and copolymers can also be used with advantage, in particular mixtures of homopolymeric acrylic acid and the copolymers of 50 to 90% by weight of acrylic acid and 50 to 10% by weight of maleic acid described above. Such mixtures, which are characterized by favorable grain properties and high storage stability, can consist, for example, of 10 to 50% by weight of homopolymeric acrylic acid and 90 to 50% by weight of acrylic acid-maleic acid copolymers. Highly polymeric polyacrylic acids can also be used in these mixtures which, when used alone, have a slightly greater tendency to stick or melt than the low molecular weight polyacrylates.

The content of homopolymeric or copolymeric (meth) acrylates in the additives is preferably 45 to 65% by weight and in particular 50 to 62% by weight.

The finely crystalline, synthetic and bound water-containing zeolite used is preferably zeolite NaA in detergent quality. It can be used as a spray-dried powder or as an undried stabilized suspension that is still moist from its manufacture. In the event that the zeolite is used as a suspension, this may contain small additions of nonionic surfactants as stabilizers, for example 1 to 3 wt .-%, based on zeolite, of ethoxylated C₁₂-C₁₈ alcohols with 2 to 5 glycol ether groups. Suitable zeolites have an average particle size of less than 10 »m (volume distribution; measurement method: Coulter Counter) and preferably contain 20 to 22% by weight of bound water. The zeolite content of the additives is preferably 8 to 30% by weight and in particular 10 to 25% by weight.

The sodium sulfate is used in anhydrous form, preferably in amounts of 4 to 15% by weight and in particular 7 to 15% by weight. When using only small amounts of zeolite, for example from 3 to 10% by weight, it is advisable to choose a somewhat higher proportion of sodium sulfate, for example in the range from 8 to 15% by weight. Sodium sulfate contents of more than 7% by weight, for example 8 to 15% by weight, fundamentally improve the grain properties and the shelf life of the additives. It is very surprising that fractions of 5 to 6% by weight of sodium sulfate are sufficient to contain additives according to the invention with a content of about Stabilize 50 wt .-% of polymeric carboxylates and ensure good flow properties.

The content of water in the additives which is not bound by the zeolite is preferably not more than 12% by weight, based on the additive, and is in particular in the range from 3 to 11% by weight.

In addition, the additives can have sodium carbonate in anhydrous form in amounts not exceeding 20% by weight. In a preferred embodiment, the additives contain 3 to 15% by weight and in particular 4 to 12% by weight of anhydrous sodium carbonate.

If desired, the additives can contain small amounts, for example 0.5 to 3% by weight, based on the additive, of surfactants, such as soap, sulfonates (for example dodecylbenzenesulfonate), organic sulfates (for example fatty alkyl sulfates) or alkypolyglycosides.

Furthermore, the additives can also contain small amounts of further constituents, such as dyes and color pigments, and can be colored uniformly or speckled. The proportion of such constituents is in each case well below 1% by weight.

The average grain size of the granular additive is usually 0.2 to 1.2 mm, the proportion of the granules being below 0.1 mm not more than 10% by weight and above 2 mm not more than 20% by weight (sieve analysis ). Preferably, at least 75% by weight, in particular at least 85% by weight, of the granules have a size of 0.2 to 1.6 mm, the proportion of the granules having a grain size between 0.1 and 0.05 mm no longer than 4% by weight, in particular not more than 3% by weight and the proportion of the grains between 1.6 and 2.4 mm not more than 20% by weight, preferably not more than 10% by weight and in particular is not more than 6% by weight. Larger proportions of fine grain generally lead to a deterioration in the induction behavior.

The production of the granules can, for example, be reduced by intensive mixing of the dry constituents with participation Amounts of liquid, in particular water, are carried out in conventional granulating devices. However, spray drying of an aqueous slurry is preferred. The slurry concentration is preferably between 50 and 68% by weight (non-aqueous fraction) and in particular between 55 and 60% by weight, the viscosity of the paste being decisive, which should not exceed 10,000 mPa · s and advantageously 2,500 to Is 6,000 mPa · s. (The viscosity is measured in the low pressure part of the spray tower at temperatures between 60 and 100 ° C using a truncated cone viscometer). The temperature of the slurry is usually between 50 and 100 ° C. The pressure at the spray nozzles is generally 30 to 80 bar, preferably 40 to 70 bar. The temperature of the counter-current dry gases in the entrance zone of the spray tower, ie in the so-called ring channel, is advantageously between 200 and 320 ° C, in particular between 220 and 300 ° C. In the area of the tower outlet it should be between 90 and 130 ° C, preferably between 100 and 125 ° C. Such comparatively high operating temperatures are advantageous for the production of a perfect product and, despite the high proportion of organic substance in the spray product, are not critical, since the self-ignition temperature is above 330 ° C., usually even above 350 ° C. Conventional spray drying systems (spray towers) with spray nozzles or spray disks can be used for spray drying, the spray nozzles being able to be arranged in one or more levels.

The spray material leaving the tower can, if necessary after cooling with flowing air, be immediately further processed or packaged. The granules are exceptionally free-flowing and can be washed into washing machines and dishwashers without leaving any residue and retain these advantageous properties even after a long storage period.

The granules according to the invention usually have a bulk density of 240 to 450 g / l, usually one of 320 to 400 g / l. If small amounts, for example 0.5 to 3% by weight, of surfactants, such as soaps, sulfonates, organic sulfates or alkyl polyglycosides, were added to the granules before the spray drying, the bulk density may be lower by amounts of 50 to 150 g / l than without this addition.

In a further and preferred embodiment, granules with a higher bulk density, in particular those of 500 to 900 g / l, are claimed. The bulk weight can be increased in a manner known per se by compacting the light granules, for which purpose in principle all techniques are suitable which are carried out under pressure and, if appropriate, with the addition of a small amount of liquid, for example by roller compacting, pelleting, extrusion or tableting. When compacting spray-dried additives, pressing by means of rollers, for example at a pressure between 100 and 200 bar, is preferred. Since the spray-dried granules have a certain plasticity under pressure, a flake-like product can be obtained in this way, which can then, if necessary, be comminuted to the desired particle size. The compacted products surprisingly retain their good dispersing and dissolving properties. The bulk density of such products is in particular between 650 and 800 g / l. Before or during compaction, liquid binders, preferably water and / or nonionic, in particular ethoxylated, nonionic surfactants, paste-like anionic surfactants and paraffin oil can be added to the granular additives. The addition of binder, the content of which, based on the compacted granulate, advantageously does not exceed 10% by weight, preferably 2 to 8% by weight and in particular 3 to 6% by weight, improves the plasticizability of the light additive and increases the density of the compacted additive. The binders can be mixed with the light additive or sprayed onto the light granulate, for example by spraying the powder stream fed to the roller with water or aqueous surfactant solutions. If water is selected as the binder, water can be omitted if the granules obtained, for example, by spray drying have not been completely dried, so that a residual moisture, for example 6 to 15% by weight of water, is retained in the spray-dried granules. The further processing of such slightly moist spray granules is a preferred method of working.

As an alternative to this, the compacting can also be carried out in a screw press or in a granulating device after the addition of appropriate amounts of liquid.

Subsequent post-drying of the compacted additives is generally not necessary and, in particular, is also not preferred. The active substance content of the non-dried compacts slightly decreases according to the amount of liquid added. The compacted granules are also free-flowing and their storage stability under unfavorable conditions, for example in a humid atmosphere, also exceeds the spray-dried products.

Examples Example 1:

A granular additive of the composition (in% by weight)
60.0% acrylic acid-maleic acid copolymer (molecular weight 70,000) in the form of the Na salt,
16.0% zeolite NaA, spray dried (20% by weight bound water),
10.6% sodium sulfate (anhydrous),
8.0% sodium carbonate (anhydrous),
5.4% water
was made as follows:
A slurry heated to 77 ° C., which contained the aforementioned solids and 47.0% by weight of water and had a viscosity of 2,500 mPa · s (60 ° C.; truncated cone viscometer from Brabender, Duisburg, Federal Republic of Germany), was also used sprayed at a pressure of 40 bar via nozzles in a drying tower. The counter-current dry gas had a temperature of 210 ° C in the ring channel and 120 ° C in the area of the tower outlet. The spray product was extremely free-flowing and had a bulk density of 320 g / l. The following particle size distribution was determined by sieve analysis (> greater than, <less than) mm > 1.6 > 0.8 > 0.4 > 0.2 > 0.1 <0.1 % By weight 2nd 19th 43 26 8th 2nd

The dust content (<0.05 mm) was less than 0.02% by weight. The product proved to be stable in storage and quickly and completely redispersible in cold water. For further use, the parts with a grain size of more than 1.6 mm and less than 0.1 mm were separated off by sieving.

Example 2:

As described in Example 1, a free-flowing, storage-stable granulate of the following composition was produced by spray drying:
50.0% by weight Na salt of the acrylic acid-maleic acid copolymer,
20.0% by weight of zeolite NaA, spray-dried,
10.0% by weight sodium sulfate (anhydrous),
9.0% by weight sodium carbonate (anhydrous),
11.0 wt% water.

Production conditions: water content of the slurry 40.1% by weight, slurry temperature 64 ° C, viscosity 2 800 mPa · s (80 ° C; truncated cone viscometer from Brabender, Duisburg, Federal Republic of Germany), spray pressure 40 bar, dry gas temperature inlet 220 ° C, outlet 110 ° C. The bulk weight was 340 g / l. Sieve analysis: mm > 1.6 > 0.8 > 0.4 > 0.2 > 0.1 <0.1 % By weight 1 14 46 27 9 3rd

The dust content was less than 0.02% by weight. The spray product showed an equally good flowability as the product according to Example 1.

The following granules were produced in an analogous manner, a copolymer corresponding to Example 1 being used. characteristic Example (% by weight) 3rd 4th 5 6 Copolymer 60 60 60 55 Zeolite 24th 20th 16 16 Sodium sulfate 9.2 9.9 8.6 8th sodium - 4th 8th 10.6 water 6.8 6.1 5.4 10.4 APG - - 2.0 - Bulk density (g / l) 320 240 160 320

The abbreviation APG stands for an alkyl polyglucoside, derived from linear C₁₀₋₁₄ alkyl chains and with an average degree of oligomerization of the glucose residue of 1.4. The product made with this addition draws is characterized by an above-average degree of whiteness and a comparatively low bulk density. The product according to Example 3 requires a somewhat lower product throughput per unit of time in the drying tower because of its somewhat difficult drying properties. All granules were free-flowing and stable in storage and proved to be completely and quickly redispersible when introduced into cold tap water.

Comparative tests

• A)
     50,0 % Na-Salz des Acrylsäure-Maleinsäure-Copolymers,
     45,3 % Natriumcarbonat (wasserfrei),
     4,7 % Wasser.
• B)
     30,0 % Na-Salze des Copolymers,
     54,8 % Natriumcarbonat (wasserfrei),
     5,0 % Natriumsulfat (wasserfrei),
     10,2 % Wasser (Wasserbindung 1,07 Mol pro Mol Natriumcarbonat)

In Versuch A wurden die gleichen Sprühbedingungen angewandt wie im Beispiel 1 beschrieben, im Versuch B lag die Turmaustritt-Temperatur der Trockengase bei 90 °C. Beide Sprühprodukte bestanden aus klebrigen, bereits unter leichtem Druck verformbaren Körnern. Das Rieselverhalten war unbefriedigend und bei dem Versuch, die Produkte zusammen mit weiteren Reinigungsmittelbestandteilen zu stabilen Granulaten weiterzuverarbeiten, traten Störungen infolge Anklebung an den Mischorgan und der Innenwand des Granuliermischers auf.Spray products of the following composition (in% by weight) were prepared as described in Example 1 above:

• A)
  50.0% Na salt of the acrylic acid-maleic acid copolymer,
  45.3% sodium carbonate (anhydrous),
  4.7% water.
• B)
  30.0% Na salts of the copolymer,
  54.8% sodium carbonate (anhydrous),
  5.0% sodium sulfate (anhydrous),
  10.2% water (water binding 1.07 moles per mole of sodium carbonate)

In experiment A the same spraying conditions were used as described in example 1, in experiment B the tower outlet temperature of the dry gases was 90 ° C. Both spray products consisted of sticky grains that could already be deformed under slight pressure. The flow behavior was unsatisfactory and when trying to process the products together with other detergent components into stable granules, problems occurred due to sticking to the mixing element and the inner wall of the granulating mixer.

Examples 7 and 8:

In order to increase the bulk density, the granules according to Examples 1 and 2 were fed to a roller compactor. The roller pressure was 150 bar. The lower-water granules were sprayed with 4% by weight of water before the pressing, while the more water-rich product was compacted according to Example 2. The pressed material was continuously in one Hammer basket grinder crushed. Granules with a grain size greater than 1.6 mm and less than 0.2 mm were sieved. The screened fine and coarse fractions were fed back into the powder stream to be compacted. The result was hard-grained, easily pourable, abrasion-resistant chip granules with the following powder specifications. example 7 8th Insert granulate according to the example 1 2nd Bulk density g / l 740 680 Grain size> 1.6 mm 2% 1 % Grain size> 0.8 mm 50% 40% Grain size> 0.4 mm 29% 34% Grain size> 0.2 mm 17% 23% Grain size <0.2 mm 2% 2%

Claims (7)

1. A granular additive for detergents containing
   40 to 75% by weight of sodium salts of at least one homopolymeric or copolymeric (meth)acrylic acid,
   1 to 35% by weight of synthetic, finely crystalline zeolite containing bound water,
   2 to 20% by weight of sodium sulfate (anhydrous) and
   1 to 15% by weight of water, but no nitrilotriacetic acid or sodium or potassium salts of nitrilotriacetic acid.
2. An additive as claimed in claim 1, characterized by a content of
   45 to 65% by weight of homopolymeric or copolymeric (meth)acrylates,
   8 to 30% by weight of water-containing zeolite,
   4 to 15% by weight of sodium sulfate (anhydrous),
   3 to 15% by weight of sodium carbonate (anhydrous) and
   3 to 11% by weight of water.
3. An additive as claimed in claim 1 or 2, characterized in that at least 75% by weight and preferably at least 85% by weight of the granules are from 0.2 to 1.6 mm in size, the percentage of granules from 0.1 to 0.05 mm in size being no more than 4% by weight and the percentage of granules from 1.6 to 2.4 mm in size being no more than 10% by weight, and the apparent density is between 320 and 400 g/l.
4. An additive as claimed in claim 1 or 2, characterized in that it contains from 2 to 8% by weight of liquid binders and has an apparent density between 650 and 800 g/l.
5. A process for the production of a granular additive for detergents, the additive containing
   40 to 75% by weight of sodium salts of at least one homopolymeric or copolymeric (meth)acrylic acid,
   1 to 35% by weight of synthetic, finely crystalline zeolite containing bound water,
   2 to 20% by weight of sodium sulfate (anhydrous) and
   1 to 15% by weight of water, but no nitrilotriacetic acid or sodium or potassium salts thereof,
   characterized in that it is produced by spray drying.
6. A process as claimed in claim 5, characterized in that the spray-dried granules are compacted under pressure.
7. A process as claimed in claim 6, characterized in that the spray-dried granules intended for compacting are moistened with water and/or are used as spray-dried granules with a high water content.