EP0070491B1 - Method for producing a low foaming silicone-containing washing agent - Google Patents

Abstract

In the production of a spray-dried detergent containing a silicone/silica mixture as an antifoaming agent, the aqueous silicone-free detergent slurry (A) is combined in the range of the spray nozzle or in the pressure line leading to the spray nozzle under conditions whereby substantial mixing is avoided in order to avoid loss of the antifoaming action, with an aqueous dispersion (B) which contains the liquid antifoaming silicone agent, which is present in a particle size of from 0.5 to 40 mu m, as well as a film-forming, high-molecular-weight polymer which is soluble or swellable in water, and which is suitable for the formation of microcapsules, preferably a cellulose ether. The microcapsules are formed during the combination of the mixture (A) with the dispersion (B) at the time of spraying, or in the dispersion itself, if electrolyte salts were added to the latter before spraying.

Description

Detergents with a content of foam-suppressing silicones are known, for. B. from DE-A-20 50 768 and DE-A-23 38 468. These silicones are organopolysiloxanes, such as alkyl and aryl polysiloxanes, in particular dimethylpolysiloxane, also their copolymers and block polymers with polyalkylene oxides and their acylation products with longer chain carboxylic acids. The silicones used as foam suppressants usually contain 0.2 to 10% by weight of highly disperse silica or highly disperse aluminum oxide, it being possible for the highly disperse silica to be obtained, for example, by thermal decomposition of silicon tetrachloride or by precipitation from silicate solutions and to be hydrophobicized by the action of organosilicon compounds.

Amounts of 0.1% by weight of silicones are normally sufficient to make detergents of conventional composition for use in household drum washing machines foam-proof. However, it is technically very difficult to distribute such small amounts homogeneously in a washing powder. If the silicone is dispersed in the aqueous batch (slurry) intended for hot spray drying, a substantial part of the effect is lost during the subsequent spray drying, so that one is forced to use two to four times the amount of the relatively complex silicone. It has therefore repeatedly been proposed to apply the silicones to solid supports, e.g. B. Mix builder salts or per compounds or embed in a carrier material and mix the granular premix obtained with the majority of the detergent, for example a spray-dried hollow sphere powder. However, several weight-controlled mixing processes are required for this, which considerably increases the effort. Another disadvantage is that the additional mixing process can lead to partial destruction of the hollow sphere structures and increased dust formation.

It has also already been proposed to atomize the foam-suppressing silicones via a separate spray nozzle leading into the spray tower and in this way to achieve a uniform distribution of the foam-suppressant. However, it has been shown that the known organopolysiloxanes can only be sprayed into droplets of sufficient small size due to their special surface-active properties with great difficulty. Rather, larger drops usually form, which leads to a largely inhomogeneous distribution and insufficient foam resistance of the detergent. In addition, the silicones come into direct contact with the detergent constituents, in particular the surfactants, as a result of which the effect of the foam suppressors decreases again in part during the subsequent storage of the detergents.

The method according to the invention avoids the disadvantages described above. The invention relates to a process for the production of a foam-damped, silicone-containing detergent by spray drying an aqueous batch containing (A) conventional surfactants, skeletal salts and other detergent constituents which are stable under the conditions of spray drying, and (B) silicones which have a foam-suppressing action, characterized in that that an aqueous formulation containing the components (A) and a separately prepared aqueous dispersion containing the silicones (B) in a particle size of 0.5-40 11 m and a water-soluble or water-swellable, film-forming polymer in a to form Microcapsules contain sufficient amount, sprayed together.

The constituents (A) contained in the aqueous batch include customary surfactants, which can be anionic, nonionic, zwitterionic or also cationic in nature. Suitable anionic surfactants are soaps, especially saturated or mono-unsaturated fatty acid sodium soaps having 12 to 22 carbon atoms, sulfonates such as alkylbenzene sulphonates, particularly sodium dodecylbenzenesulfonate, further alkanesulfonates, olefin sulfonates, "sulfo fatty acids, alkyl sulfosuccinates and alkyl ether sulfonates and sulfates such as alkyl sulfates, in particular fatty alcohol sulfates and Fettalkoholglykolethersulfate . Surfactants with aliphatic radicals are usually straight-chain or methyl-branched (oxo radicals), contain 10 to 20 carbon atoms and are present as salts of sodium, potassium, ammonium or organic ammonium bases. Typical nonionic surfactants are, in particular, alkyl or alkenyl polyethylene glycol ethers with straight-chain and / or methyl-branched C ₁₀ -C ₂₀ radicals and 3 to 30 glycol ether groups, and also glycol ether derivatives with the same number of C atoms and glycol ether groups, which differ from alkylphenols, alkylamines, thioalcohols, Derive fatty acids and fatty acid amides and block polymers of ethylene and propylene oxide known under the name Piuronics ^* . Mixtures of various anionic and / or nonionic surfactants can also be present.

The constituents (A) include conventional skeleton salts (builder salts), such as polymer phosphates, in particular sodium tripolyphosphate, sodium silicate of the composition Na ₂ 0: Si0 ₂ , such as 1: 1-1: 3.5, sodium carbonate and, in particular, water-insoluble, finely crystalline or amorphous alkali aluminum silicates Formula (Na ₂ 0) - A1 ₂ 0 ₃ - (SiO ₂ ) y with x = 0.7 - 1.5, y = 1.3 - 4, which contain bound water and a calcium binding capacity of at least 50 mg CaO / g Have active substance.

The skeletal salts also include the known sequestering agents, such as aminopolycarboxylic acids, polyphosphonic acids, which may have hydroxyalkyl or amino groups, polycarboxylic acids, ether carboxylic acids, hydroxycarboxylic acids and polymeric carboxylic acids, optionally having hydroxyl, ether or oxo groups, which are salts of Na , K, ammonium or organic ammonium bases can be present. Representatives of these sequestering agents are, for example, nitrilotriacetic acid, ethylenediaminotetraacetic acid, aminotri- (methylenephosphonic acid), ethylenediaminotetraphosphonic acid, 1-hydroxyethane-1,1-diphosphonic acid, methylenediphosphonic acid, ethylenediphosphonic acid and salts of the higher homologues of the polyphosphonic acids mentioned. Suitable polycarboxylic acids are citric acid, tartaric acid, benzene hexacarboxylic acid and tetrahydrofuran tetracarboxylic acid as well as polycarboxylic acids containing carboxymethyl ether groups, such as 2,2'-oxydisuccinic acid, diglycolic acid, triscarboxymethylglycerol and biscarboxymethylglyceric acid. Suitable representatives of polymeric carboxylic acids are those with a molecular weight of at least 350, such as polyacrylic acid, polymethacrylic acid, poly-a-hydroxyacrylic acid, polymaleic acid, polyitaconic acid, polymesaconic acid, polybutene tricarboxylic acid and the copolymers of the corresponding monomeric carboxylic acids with one another or with ethylenically unsaturated compounds, such as ethylene, propylene, Isobutylene and vinyl methyl ether, furthermore the polycarboxylic acids containing hydroxyl or aldehyde groups, which can be obtained by polymerizing acrolein and then converting to Canizzaro.

Other constituents to be assigned to substance group (A) are optical brighteners, anti-graying substances such as carboxylmethyl cellulose, methyl cellulose or methyl hydroxypropyl cellulose, stabilizers such as magnesium silicate, neutral salts such as sodium sulfate, powder improvers such as benzene, toluene, xylene and cumene sulfonate and sodium sulfonate as well as sodium .

Accordingly, the abovementioned compounds, which are to be attributed to component (A), are customary detergent constituents which are stable under the conditions of hot spray drying and are mixed in an aqueous, pumpable and sprayable batch. Depending on the composition, the water content of such an approach generally amounts to 50-25% by weight. The aqueous batch is usually conveyed from the batch container to a high-pressure pump and pumped from there via a pressure line (riser line) to the spray nozzles, of which several are usually attached in the head of the spray tower and are connected to one another via a ring line. In some cases, the aqueous batch is degassed in a vacuum chamber before it is transferred to the high pressure section.

The combination of the aqueous batch containing component (A) with the aqueous batch containing component (B), which is described in more detail below, is preferably carried out in a region which comprises the spray nozzles themselves and the high-pressure line leading to the spray nozzles. If the union takes place in the spray nozzles, these consist of two-substance nozzles with separate supply of the two partial streams. However, with equal success, but with less technical effort, the two partial streams can also be brought together in the high-pressure line leading to the spray nozzles, it being possible to use the single-substance nozzles customary in spray technology. In this case, the union of the two partial streams should preferably take place near the spray nozzle or shortly before the distributor ring to which the circularly arranged spray nozzles are connected. Additional internals promoting the homogenization of the two partial flows are to be avoided, since this could result in a loss of effectiveness. This way of working is preferred.

aufgebaut sind, in der R und R' unabhängig voneinander Alkylgruppen, wie Methyl-, Ethyl-, Propyl- und Butylgruppen oder Arylgruppen, z. B. Phenylgruppen bedeuten und x für Zahlen von etwa 20 bis etwa 2000 steht. Als Endgruppen kommen z. B. Alkyl- oder Hydroxylgruppen in Frage. Besonders geeignet sind Polydimethylsiloxane, die eine Viskosität von 2 bis 150 cm²/s/25 °C aufweisen. Die vorgenannten, bei Raumtemperatur flüssigen Organopolysiloxane können auch im Gemisch mit bekannten Polysiloxanharzen vorliegen, die, wie z. B. in den US-A-2676 182, 26 78 893 oder 32 35 509 beschrieben, durch Umsetzung von Alkylsiloxanen mit Chlorsilanen oder Si0₂ erhältlich sind. Solche Gemische sind z. B. aus der DE-B-16 19859 bekannt. Weiterhin sind selbstemulgierende Organopolysiloxane brauchbar, die aus Blockpolymeren von Alkyl- bzw. Arylpolysiloxanen und Polyglykolethern bestehen und z. B. aus den DE-A-23 45 335, 24 43 853, 25 18 053 und 25 34 250 bekannt sind.The second, the aqueous component containing component (B), which is also spray dried but separately from the component (A) containing approach, contains the foam-suppressing silicones, which, as stated at the beginning, are organopolysiloxanes which are in the A mixture with highly disperse or silanized (hydrophobized) silica or highly disperse aluminum oxide is present. Suitable silicones for the purposes of the invention are those which consist of elements of the formula

are built up in which R and R 'independently of one another alkyl groups, such as methyl, ethyl, propyl and butyl groups or aryl groups, for. B. phenyl groups and x represents numbers from about 20 to about 2000. As end groups come e.g. B. alkyl or hydroxyl groups in question. Polydimethylsiloxanes with a viscosity of 2 to 150 cm ² / s / 25 ° C. are particularly suitable. The above-mentioned, organopolysiloxanes which are liquid at room temperature can also be present in a mixture with known polysiloxane resins which, for. B. in US-A-2676 182, 26 78 893 or 32 35 509 described, are obtainable by reacting alkylsiloxanes with chlorosilanes or Si0 ₂ . Such mixtures are e.g. B. from DE-B-16 19859 known. Furthermore, self-emulsifying organopolysiloxanes are usable, which consist of block polymers of alkyl or aryl polysiloxanes and polyglycol ethers and z. B. from DE-A-23 45 335, 24 43 853, 25 18 053 and 25 34 250 are known.

The aqueous batch containing the silicone dispersion also has a content of film-forming, to form water soluble or water swellable high molecular weight polymers in _'an amount which is sufficient to microcapsules, in which the silicones are incorporated by spray-drying substantially. The weight ratio of silicone to film-forming polymers is preferably 10: 1 to 2: 1 and in particular 6: 1 to 3: 1. The silicone content of the aqueous batch can be 2 to 25% by weight, preferably 5 to 20% by weight. , and the content of film-forming polymers 0.2 to 10 wt .-%, preferably 1 to 5 wt .-%.

Suitable water-soluble or swellable, film-forming polymers are in particular cellulose ethers, such as carboxymethyl cellulose (e.g. as the sodium salt) and methyl cellulose, furthermore hydroxyalkyl celluloses, such as hydroxyethyl cellulose, hydroxypropyl cellulose or mixed ethers, such as methyl hydroxypropyl cellulose and methyl carboxymethyl cellulose. Mixtures of different cellulose ethers can also be used with advantage.

Other useful high polymers are soluble or depolymerized starch, starch ethers, starch esters, and also synthetic polymers such as polyacrylates, polymethacrylates, polyacrylamide, polyvinyl alcohol or partially saponified polyvinyl acetate, polyvinyl pyrrolidone, polymaleinates and copolymers which contain the elements of the aforementioned polymers. Mixtures of the homopolymers and copolymers mentioned are also suitable.

In the preparation of the aqueous dispersion of the silicones, it is expedient to proceed by first completely dissolving or allowing the polymers to swell and then adding the silicones. Suitable mechanical mixing, stirring and emulsifying devices ensure that the silicones have a particle or droplet size of 0.5 to 40 μm, preferably 1 to 20 μm. Such a dispersion is sufficiently stable so that it can be conveyed to the spraying system without any significant segregation and can be sprayed together with the detergent-containing slurry in the manner described.

In a further preferred embodiment, water-soluble electrolyte salts can be added to the aqueous batch containing the silicones and high polymers after the fine dispersion of the silicones has been completed. As a result, the high polymers are wholly or partly precipitated from their aqueous solution or swelling, so that the microcapsules already form in the aqueous batch. The electrolyte salt content of the suspension can be up to 25% by weight, preferably 5 to 20% by weight. Suitable electrolyte salts are e.g. B. the chlorides, sulfates and nitrates of sodium, potassium and magnesium and the silicates, phosphates, pyrophosphates and polymer phosphates, acetate, lactates and citrates of sodium and potassium. Sodium sulfate and sodium phosphates, including the polymer phosphates, are preferably used as electrolyte salts. Dispersions in which the silicones are already encapsulated have the advantage that they can be stored for a long time. Framed dispersions can be homogenized again by simply stirring. If the use of electrolyte salts is dispensed with, the microcapsules form at the moment of their encounter with the aqueous mixture which contains the components (A).

The amounts of the two substreams are regulated by means of doses so that the spray-dried detergent 0.02 to 0.4, preferably 0.05 to 0.2 and in particular approximately 0.1 to 0.15% by weight when leaving the drying tower Contains silicone. These amounts are sufficient for effective foam damping in most cases. They are well below the amounts of silicone which are required if the foam depressors are dispersed directly in the aqueous batch which contains the majority of the detergent constituents (component A).

It was highly surprising that when the two separately produced batches were combined in the high-pressure line or in the spray nozzle, stable microcapsules preventing emulsification of the silicones in the detergent slurry were formed, or that the pre-formed microcapsules withstood the extreme shear stresses and the high ones Drying temperatures, which usually prevail in a drying tower, survive largely without damage. Furthermore, it has surprisingly been found that the agents or the microcapsules contained therein and intimately cemented with the detergent particles are largely stable in storage, so that there is no appreciable decrease in the foam-inhibiting properties due to interactions between the silicone and the detergents during a longer storage period existing surfactants and washing alkalis.

Examples example 1

In a 110 liter container, 2 kg of methyl cellulose and 1.7 kg of sodium carboxymethyl cellulose were first dissolved in 85 kg of water at 20 ° C. with stirring (propeller stirrer). After 1 hour, 11.3 kg of silicone oil (product Y 6067 from UCC) were distributed over the course of 10 minutes with stirring. The fine emulsification was carried out in such a way that the contents of the container were pumped through a pipe loop by means of a high-speed emulsifying device which was equipped with several rotor and stator disks. After about 30 minutes a steady state was reached with a droplet size of 1-20 11m. The silicone oil emulsion was then passed through a high-pressure pump and fed at a pressure of 52 bar into the pressure line leading to the spray nozzles and with the Detergent slurry combined. The feed was carried out immediately before the riser passed into the ring line leading to the individual spray nozzles (single-substance nozzles).

The drying tower was charged with air at an inlet temperature of 230 ° C. and an outlet temperature of 87 ° C., the air being conducted in countercurrent and swirl. The flow rate of the aqueous batches was controlled so that 0.13% by weight of silicone oil was present in the spray-dried tower powder. After mixing in additional sodium perborate, the silicone oil content of the ready-to-use washing powder fell to 0.11% by weight. The finished detergent contained as essential components about 15% by weight of anionic and nonionic surfactants, 25% by weight of sodium tripolyphosphate, 24% by weight of sodium aluminosilicate, 4.5% by weight of sodium silicate, 22% by weight of sodium perborate and 4.5% by weight of other customary detergent components, such as graying inhibitors, sequestering agents, optical brighteners, fragrances and sodium sulfate.

After one week of storage, the detergents were checked for their foaming behavior in a conventional household drum washing machine with a maximum capacity of 5 kg dry laundry with a detergent insert of 7.5 g / l and a filling of 2 kg clean cotton fabric in the temperature range between 30 ° and 95 ° C checked. When using soft water of 6 ° dH or hard water of 16 ° dH, there was no excessive foaming or over-foaming at any time.

For comparison, a detergent was used in which the same silicone oil had been mixed onto the sodium perborate subsequently added to the tower powder, the proportions being chosen so that the content of the finished detergent was also 0.11% by weight. While the foaming behavior of the two compositions to be compared was the same after a storage time of 24 hours, it was found after a storage time of 7 days that the effect of the mixed comparison sample compared to the sample according to the invention had deteriorated significantly, ie. H. the agents according to the invention proved to be superior to the known agents with regard to the constancy of action.

Example 2

Example 1 was repeated, but the partial streams were not combined in the pressure line, but instead were fed as separate streams to the feeds of a two-component nozzle. With regard to the foam properties, the compositions proved to be equivalent to those according to Example 1.

Example 3

As described in Example 1, 1.52 kg of methyl cellulose and 1.16 kg of Na-carboxymethyl cellulose were dissolved in 73.32 kg of water with stirring, after which 10 kg of the silicone oil were mixed in after 1 hour. After fine dispersion (droplet size 1-20 microns) 14 kg of anhydrous sodium sulfate were added in portions within 20 minutes with stirring. Some of the cellulose ethers precipitated and formed stable microcapsules. As described in Example 1, the capsule suspension was fed into the high-pressure line leading to the single-component nozzles. The amounts were metered in such a way that the content of the agent after the spray drying and the admixing of 20% by weight of sodium perborate was 0.1% by weight of silicone. The agents obtained proved to be foam-proof under test and practical conditions.

Claims (10)

₁. A process for the production of a foam-inhibited, silicone-containing detergent by spray-drying an aqueous mixture containing (A) standard surfactants, builder salts and other detergent ingredients which are stable under the spray-drying conditions and (B) foam-inhibiting silicones, characterized in that an aqueous mixture containing the components (A) and an aqueous dispersion prepared separately therefrom which contains the silicones (B) in a particle size of from 0.5 to 40 ₁1m and a water-soluble or water-swellable film-forming polymer in a quantity sufficient for forming microcapsules are sprayed together.

2. A process as claimed in Claim 1, characterized in that the aqueous mixtures containing components (A) and (B) are combined with one another in a zone which covers the spray nozzles and the high-pressure line leading to the spray nozzles.

3. A process as claimed in Claims 1 and 2, characterized in that the mixture containing the components (A) and the mixtures containing the components (B) are each separately delivered to one of the two lines feeding a two-component nozzle and sprayed together.

4. A process as claimed in Claims 1 and 2, characterized in that the mixture containing the components (A) and the mixture containing the components (B) are combined in the pressure line leading to the spray nozzles and sprayed together by means of one-component nozzles.

5. A process as claimed in Claims 1 to 4, characterized in that a suspension of component (B), in which the ratio by weight of silicone to film-forming polymer amounts to between 10 1 and 2 : 1, is used.

6. A process as claimed in Claims 1 to 5, characterized in that the suspension contains from 2 to 25 % by weight and preferably from 5 to 20 % by weight of silicone and from 0.2 to 10 % by weight and preferably from 1 to 5% by weight of film-forming polymer.

7. A process as claimed in Claims 1 to 6, characterized in that at least one compound from the class of cellulose ethers, preferably carboxymethyl cellulose and/or methyl cellulose, is used as the film-forming polymer.

8. A process as claimed in Claims 1 to 7, characterized in that a silicone dispersion having a particle size of from 1 to 20 ₁1m is used.

9. A process as claimed in Claims 1 to 8, characterized in that a suspension of component (B) is used to which up to 25 % by weight and preferably from 5 to 20 % by weight of an electrolyte, particularly sulfates, phosphates and polymer phosphates of sodium, is additionally added after the fine dispersion of the silicones.

10. A process as claimed in Claims 1 to 9, characterized in that the two aqueous mixtures are combined in such quantities that the spray-dried detergent contains from 0.02 to 0.4 % by weight and preferably from 0.05 to 0.2 % by weight of silicone.