CA2335840A1 - Method for producing alkaline aqueous cleaning agents in the form of creams - Google Patents

Abstract

According to the inventive method, a premixed material is initially produced including one or several alcohols (a) and a powdery substance (b) of the gro up consisting of builder substances, antifoaming agents, surface active agents, salts and their mixtures. Said premixed material is then mixed with concentrated lye that may contain additional detergent active substances by stirring and by simultaneously or subsequently mixing with an inert gas. Normally, air is used as inert gas. The resulting cream products are particularly suitable for cleaning crockery and installations and devices in the food industry but also for washing textiles.

Description

"Method for producing alkaline-aqueous cleaning agents in the form of creams"
The invention described below is in the field of strongly alkaline cleaning agents, as are used, in particular, in the commercial sector for the cleaning of dishes and of appliances and equipment in the food industry, but also for the washing of textiles.
Highly alkaline cleaning agents for the cleaning of hard surfaces and textiles are known in a very wide variety of forms. Thus, for example, International Patent Applications WO 96/27653, WO 97/41203 and WO 98/13466 describe cleaning agents in the form of pastes and blocks which, in addition to alkali metal hydroxide, comprise certain alcohols, and optionally further cleaning active ingredients.
The object of the present invention is to find a novel supply form for highly alkaline aqueous cleaning agents which has advantages over the previously known forms.
The present invention provides a method for producing alkaline-aqueous cleaning agents in the form of creams, in which a premix of a) one or more alcohols of the general formula I
RlRzR3COH ( I ) in which R1 and R2, independently of one another, are a hydrogen atom or a linear or branched, saturated or unsaturated, substituted or unsubstituted C1 to C3-alkyl group or a - ( CH2 ) n-CHz-OH group where n - 0 to 5 , and R3, independently of the others, is a hydrogen atom, a linear or branched, saturated or unsaturated, substi-tuted or unsubstituted C1 to C18-alkyl group or a - (CHz) mNR4R5 group, in which R4 and R5, independently of one another, are a hydrogen atom or a methyl group or are the - (CH2) P-OH group or the - ( (CHZ) q-O) rH group and m, p, q and r, independently of one another, may have values between 2 and 5, where the alcohol or alcohols constitute between 0.1 and 30% by weight, preferably between 1 and 15% by weight and, in particular, between 3 and 8% by weight, based on the finished cleaning agent, and b) a pulverulent substance from the group of builder substances, foam inhibitors, surfactants, salts and mixtures thereof, in an amount of from 2 to 70% by weight, preferably from 10 to 60% by weight and, in particular, from 30 to 50% by weight, based on the finished cleaning agent, is mixed with concentrated alkali metal hydroxide solution, which may optionally comprise further cleaning active ingredients, in an amount of from 21 to 70o by weight, preferably 35 to 55o by weight and, in parti-cular, from 45 to 55% by weight, based on the finished cleaning agent, with stirring and the simultaneous or subsequent mixing in of an inert gas. Preferably, the inert gas used is customary air.
The novel method permits products in the form of creams to be produced which, compared with products of identi-cal composition but prepared without gas, are distinguished by a lower density and, surprisingly, also by a lower viscosity. The preparation can there-fore be carried out directly at room temperature. The novel products do not subsequently harden. They are pumpable and, as a result, can be dosed more easily and, surprisingly, dissolve more rapidly in water.
In a particularly preferred embodiment of the novel method, the mixing-in of the gas is effected by, during mixing of the components or subsequently thereto, stirring rapidly such that gas from the gas atmosphere which is present above it is drawn into the viscous mixture and is distributed uniformly therein.

The inert gases used are preferably noncombustible gases, for example nitrogen, argon or, particularly preferably, customary air, the low content of carbon dioxide not interfering in the method according to the invention. The proportion of gas is measured in the method such that its proportion in the finished cleaning agent is between about 1 and about 35 percent by volume, preferably between about 2 and about 25 percent by volume and, in particular, between about 5 and about 15 percent by volume. The particular composition of the other components of the cleaning agent ensures a stable dispersion of the finely-dispersed gas in the cleaning agent.
The alcohols of the formula I used in the method according to the invention are monohydric or polyhydric aliphatic alcohols or aminoalcohols. Preference is given to using methanol, ethanol, propanol, isopropanol, ethylene glycol, propylene glycol, butylene glycol, glycerol, ethanolamine, diethanolamine and triethanol-amine. Of these alcohols, particular preference is in turn given to ethylene glycol, propylene glycol and 1,3-butanediol. It is of course also possible to use mixtures of two or more alcohols.
The concentrated alkali metal hydroxide solution used is preferably potassium hydroxide solution, sodium hydroxide solution, mixtures of potassium and sodium hydroxide solutions and, in particular, sodium hydroxide solution on its own. According to the invention, concen-trated alkali metal hydroxide solution is understood as meaning one which has a content of alkali metal hydroxide of at least 30% by weight. Preferably, the content of alkali metal hydroxide in the hydroxide solu-tion should be between about 30 and about 60o by weight, in particular between about 42 and about 55o by weight.

In the course of the method according to the invention, a premix comprising a) one or more alcohols of the general formula I and b) a pulverulent substance from the group of builder S substances, foam inhibitors, surfactants, salts and mixtures thereof is firstly prepared, and this is then mixed with the concentrated alkali metal hydroxide solution. The preparation of the premix comprising a) and b) is unimportant and can be carried out in various ways. As a rule, the alcohols are sprayed onto the powder with agitation, although, in particular cases, it is also possible to introduce the alcohols of the formula I as liquid and to stir the pulverulent solids one after the other into this liquid. If desired, liquid nonionic surfactants and/or paraffin oil may also be incorporated into the premix.
The mixing of the premix comprising a) and b) with the concentrated alkali metal hydroxide solution can, for example, be carried out by stirring the premix comprising a and b into the concentrated alkali metal hydroxide solution. It is, however, also possible to stir the alkali metal hydroxide solution into the premix. The latter variant has the advantage that it can be carried out in just one batch container. The inert gas can be mixed in during the mixing of the alkali metal hydroxide solution with the premix comprising a) and b), or subsequently thereto.
Incorporation of the gas during mixing has the advantage that it is not possible for excessive viscosities to arise which impair stirring. If the gas is not mixed in until afterwards, then this mixing-in is preferably carried out immediately after the mixing of the premix comprising a) and b) with the alkali metal hydroxide solution in order to prevent post-thickening of the mixture. Preferably, the method according to the inven-tion is carried out at temperatures of approximately room temperature, although, in principle, it is also -possible to work at higher temperatures up to about 65°C, preferably up to about 42°C, and then to cool the product in the form of a cream optionally with stirring.
Incorporation of the gas into the alkaline cleaning agent can be effected in various ways. For example, it is possible to bubble the gas into the product through appropriately arranged nozzles, stirring expediently being carried out simultaneously such that relatively large gas bubbles are divided, and uniform distribution of the gas within the product is achieved. Another preferred possibility consists in stirring the liquid to viscous cleaning agent mixture so rapidly that gas from the gas atmosphere present above it is drawn into the viscous mixture and is distributed uniformly therein. For this variant, anchor stirrers with strippers, where appropriate also as counter rotating double-motion mixers, have proven particularly suitable.
As a rule, the preparation method according to the invention is terminated with the mixing of the premix comprises a and b and the concentrated sodium hydroxide solution, which optionally comprises further detergent active ingredients, and the uniform mixing-in of the inert gas. However, in particular cases, after these steps, yet further components can also be mixed into the cleaning agent if this seems expedient. For example, in particu-lar finely divided solid alkali metal hydroxide, prefer-ably sodium hydroxide, can subsequently be mixed into the cleaning agent in amounts of from about to by weight to about 25o by weight, in particular from about 5% by weight to about 15% by weight, without the basic creamy character of the product being impaired. It is, however, also possible at this point to mix further pulverulent constituents of the type already mentioned above or else, for example, coated chlorine carriers, coated enzymes, coated phosphates and other complexing agents, and liquid constituents, such as, for example, paraffin oil and nonionic surfactants, into the cleaning agent.
The pulverulent proportions may be used entirely as component b for the preparation of the premix, although it is also possible, as described above, to mix in some afterwards. This proportion mixed in afterwards is preferably not more than about 60o by weight, in particular not more than about 40% by weight, based on the pulverulent constituents overall.
There now follows a description of the other consti-tuents of the cleaning agents prepared according to the invention.
The surfactants which may be used are either anionic surfactants or cationic surfactants, amphoteric surfac-tants and nonionic surfactants. Depending on the area of application, e.g. in the case of the cleaning of dishes and surfaces, weakly foaming surfactants, especially nonionic surfactants, may be present in an amount of up to loo by weight, preferably 1 to 5% by weight and particularly preferably 2 to 4o by weight.
Usually, for machine dishwashing, extremely low-foam compounds are used. These include, preferably, C12-C18-alkylpolyethylene glycol polypropylene glycol ethers having in each case up to 8 mol of ethylene oxide and propylene oxide units in the molecule. It is, however, also possible to use other nonionic surfactants known as low-foam, such as e.g. Clz-C18-alkylpolyethylene glycol polybutylene glycol ethers having in each case up to 8 mol of ethylene oxide and butylene oxide units in the molecule, and also terminally capped alkylpolyalkylene glycol mixed ethers.
If the agents prepared according to the invention are intended for the machine washing of laundry, then a higher surfactant content is advisable, which, as a -rule, may amount to 20% by weight, preferably 0.1 to 15% by weight, particularly preferably 1 to 10% by weight and most preferably 2 to 4% by weight, based on the total agent. Then, in addition to nonionic, cationic and amphoteric surfactants, use is made in particular of anionic surfactants from the group of alkylbenzene-sulfonates, fatty alcohol sulfates, fatty alcohol ether sulfates and other known anionic surfactants.
Paraffin oil, which may be present according to the invention in an amount up to 10% by weight, means long-chain hydrocarbons which may be branched or unbranched.
In a preferred embodiment, they are added to the agents prepared according to the invention in amounts between 0.1 and 8% by weight, particularly preferably between 0.5 and 3% by weight. The paraffin oil may, like liquid nonionic surfactants, be mixed in at various stages of the method, for example into the premix comprising a) and b), into the sodium hydroxide solution, or else into the creamy product.
The builder substance present in the cleaning agents according to the invention may, in principle, be any substance which is known in the prior art as builder suitable in the widest sense for detergents and cleaning agents. Preference is given to using water-soluble builder substances. The coated builder substances known in the prior art may also be used, and are even preferable if chlorine-containing bleaches are used.
Suitable builder substances are, for example, alkali metal phosphates, which may be present in the form of their sodium or potassium salts. Examples thereof are:
tetrasodium diphosphate, pentasodium triphosphate, so-called sodium hexametaphosphate, and the corresponding potassium salts, or mixtures of sodium hexametaphosphate, g -and the corresponding potassium salts or mixtures of sodium and potassium salts.
Mention is also to be made of complexing agents, such as e.g. nitrilotriacetate or ethylenediaminetetraacetate.
Soda and borax are also examples of builder substances for the purposes of the present invention.
Further possible water-soluble builder components are e.g. organic polymers of natural or synthetic origin, especially polycarboxylates. Suitable are, for example, polyacrylic acids and copolymers of malefic anhydride and acrylic acid, and the sodium salts of these polymeric acids. Commercially available products are e.g. Sokalan0 CP 5 and PA 30 from BASF, Alcosperse0 175 and 177 from Alco, LMW~ 45 N and SP02 ND from Norsohaas.
Suitable natural polymers include, for example, oxidized starch and polyamino acids, such as polyglutamic acid or polyaspartic acid, e.g. from Cygnus, Bayer, Rohm &
Haas, Rhone-Poulenc or SRCHEM.
Further possible builder components are naturally occurring hydroxycarboxylic acids, such as e.g. mono-, dihydroxysuccinic acid, a-hydroxypropionic acid, citric acid, gluconic acid, and salts thereof. Citrates are preferably used in the form of trisodium citrate dihydrate.
Suitable builder substances are also amorphous metasilicates or phyllosilicates. Crystalline phyllo-silicates are also suitable builders provided they are sufficiently alkali-stable; crystalline phyllosilicates are sold by Hoechst AG (Germany) under the trade name Na-SKS, e.g. Na-SKS-1 (Na2S122O45~xH20, kenyaite) , Na-SKS-2 (Na2Sy4O29-xHzO, magadiite) , Na-SKS-3 (Na2Sie01-,~xH20) , Na-SKS-4 (Na2Si409~xH20, makatite) , Na-SKS-5 (a-Na2Si205) , Na-SKS-7 ((3-Na2Si2O5, natrosilite) , Na-SKS-11 (2-NazSi205) and Na-SKS-6 (8-NazSi205) .

- g -Particularly preferred builder substances are those chosen from the group consisting of pentasodium triphosphate, trisodium citrate, nitrilotriacetate, ethylenediaminetetraacetate, soda, alkali metal silicate and mixtures thereof. The content of builder substances may amount to about 60% by weight in the agents prepared according to the invention and is preferably between about 15 and about 45% by weight.
Bleaches customary in detergents and cleaning agents may also be present in the agents prepared according to the invention, if so preferably in amounts between 0.5 and 10% by weight and particularly preferably between 1.5 and loo by weight. These may be chosen from the group of oxygen-based bleaches, such as e.g. sodium perborate, including in the form of its hydrates, or sodium percarbonate, or from the group of chlorine-based bleaches, such as N-chloro-p-toluenesulfonamide, tri-chloroisocyanuric acid, alkali metal dichloro-isocyanurate, alkali metal hypochlorites, and agents releasing alkali metal hypochlorites, particularly alkali-stable bleach compositions being preferred.
These may either be alkali-stable substances, or components stabilized by suitable methods, such as, for example, by surface-coating or -passivation.
Further suitable ingredients in the cleaners prepared according to the invention are antifoams . These may be used in concentrations between 0.1 and S% by weight, preferably 0.5 and 3% by weight if a chosen surfactant is too highly foaming under the given conditions, or have a foam-suppressing action on foaming food residues in the dishwasher. Antifoams (foam inhibitors) means all foam-suppressing substances known in the prior art, but preferably those based on silicone and paraffin, particularly preferably those based on paraffin.

Optional ingredients are further customary cleaning agent constituents, such as e.g. neutral salts, such as, for example, sodium sulfate, dyes, enzymes in coated form, or alkali-stable perfume substances. Although ingredients which have an abrasive action may, in principle, be present, the cleaning agents prepared according to the invention are preferably free therefrom.
Although thickeners, such as e.g. swellable phyllo-silicates of the montmorillonite type, bentonite, kaolin, talc or carboxymethylcellulose, may in addition optionally be used in order to vary the rigidity, they are not required for achieving the desired consistency in the method according to the invention, i.e. it is possible to dispense with such thickeners.
The use of high-melting paraffins or high-melting poly-ethylene glycols for solidifying mixtures is not required here to achieve success according to the invention either. However, such agents may additionally be present. Neither is it necessary to use long-chain fatty acids and long-chain fatty acid salts, as are used in the soap industry (chain lengths between C12 and C18), to achieve the consistency according to the invention. However, such substances are not usually detrimental to success according to the invention. The production of liquid-crystalline structures is likewise not necessary for the thickening.
The creamy products prepared according to the invention preferably have viscosities from about 20,000 to about 150,000 mPas, measured at 20°C using a Brookfield viscometer (5 revolutions per minute, spindle according to viscosity) . The viscosity can here be varied within wide limits by the amount of gas incorporated and depends only to a surprisingly low degree on the viscosity of the gas-free basic mixture, which is determined by its composition. A subsequent change in the viscosity is possible, for example, by rolling the cream on a roller mill.
The creamy nature of the products prepared according to the invention facilitates their dosing and improves quite considerably the dissolution rate in water. Low-viscosity examples of the cleaning agents prepared according to the invention which are able to flow under their own weight may be supplied, for example, in cap-standing bottles, from which they can be taken effortlessly. Products of higher viscosity are also suitable for conveyance by means of pressurized pumps and thus permit simple dosing in corresponding automatic cleaning apparatuses. Dosing from appropriate cartridge dosing devices is also possible without problems.
Example A Lodige plowshare mixer with a capacity of 100 liters was charged with 6.75 kg of sodium nitrilotriacetate (powder 92% pure), 5.7 kg of calcined soda and 0.3 kg of pulverulent paraffin foam inhibitor and 1.5 kg of ethylene glycol were introduced via a nozzle over the course of 1 minute with circulation of the mixer. As a result of subsequent circulation for a further 3 minutes, the premix was homogenized. The premix was then stirred in portions into sodium hydroxide solution in a 50 liter stirred vessel and stirred using an anchor stirrer in an air atmosphere (100 revolutions per minute). During the addition, the temperature rose to values somewhat above 30°C. When the addition was complete, the mixture was stirred for a further 20 minutes under these conditions and cooled to below 30°C during this. The creamy product was then homogenized using a roller mill with a pressing force of 29 bar at a gap width of 0.2 mm. The density of the finished product was 1.4. It comprised 6.5 percent by volume of air. The viscosity, determined using a Brookfield viscometer at 20°C, 5 revolutions per minute with spindle 7, was 120,000 mPas.

Claims (10)

Claims

1. A method for producing alkaline-aqueous cleaning agents in the form of creams, in which a premix of a) one or more alcohols of the general formula I
R1R2R3COH (I) in which R1 and R2, independently of one another, are a hydrogen atom or a linear or branched, saturated or unsaturated, substituted or unsubstituted C1 to C3-alkyl group or a - (CH2)n-CH2-OH group where n - 0 to 5, and R3, independently of the others, is a hydrogen atom, a linear or branched, saturated or unsaturated, substituted or unsubstituted C1 to C18-alkyl group or a - (CH2)m NR4R5 group, in which R4 and R5, independently of one another, are a hydrogen atom or a methyl group or are the - (CH2) p-OH group or the - ((CH2) q -O)r H group and m, p, q and r, independently of one another, may have values between 2 and 5, where the alcohol or alcohols constitute between 0.1 and 30% by weight, based on the finished cleaning agent, and b) a pulverulent substance from the group of builder substances, foam inhibitors, surfactants, salts and mixtures thereof, in an amount of from 2 to 70% by weight, based on the finished cleaning agent, is mixed with concentrated alkali metal hydroxide solution, which has a content of alkali metal hydroxide of between 30 and 60 % by weight and may optionally comprise further cleaning active ingredients, in an amount of from 21 to 70% by weight, based on the finished cleaning agent, with stirring and the simultaneous or subsequent mixing in of an inert gas, including air, where the amount of gas is measured such that its proportion in the finished cleaning agent is between 1 and 35% by volume.

2. The method as claimed in claim 1, in which the mixing-in of the gas is effected by sufficiently rapid stirring of the other components under an appropriate gas atmosphere, in particular under air.

3. The method as claimed in either of claims 1 and 2, in which the amount of alcohol of the formula I is between 1 and 15% by weight and preferably between 3 and 8% by weight, based on the finished cleaning agent.

4. The method as claimed in any of claims 1 to 3, in which the proportion of the pulverulent constituent (b) is 10 to 60% by weight and preferably 30 to 50% by weight, based on the finished cleaning agent.

5. The method as claimed in any of claims 1 to 4, in which concentrated alkali metal hydroxide solution is used in an amount of from 35 to 55% by weight and preferably from 45 to 55% by weight, based on the finished cleaning agent, where this alkali metal hydroxide solution has a content of alkali metal hydroxide of from, preferably, 42 to 55% by weight.

6. The method as claimed in any of claims 1 to 5, in which the amount of inert gas is measured such that its proportion in the finished cleaning agent is 2 to 25% by volume and in particular 5 to 15%
by volume.

7. The method as claimed in any of claims 1 to 6, in which, following the mixing of the premix comprising a) and b) with the concentrated alkali metal hydroxide solution with the introduction of gas, finely divided solid alkali metal hydroxide is mixed in with further stirring, preferably in amounts of from 1 to 25% by weight, in particular from 5 to 15% by weight, based on the finished cleaning agent.

8. The method as claimed in any of claims 1 to 7, in which the alkali metal hydroxide solution used is sodium hydroxide solution and the solid alkali metal hydroxide optionally used is sodium hydroxide.

9. The method as claimed in any of claims 1 to 8, in which the pulverulent constituent b) is chosen from the group consisting of Na2CO3, sodium nitrilo-triacetate, sodium methylenediaminetetraacetate, sodium polyphosphates, pulverulent foam inhibitors and mixtures thereof.

10. The use of a cleaning agent obtainable as in any of claims 1 to 9 for the cleaning of hard surfaces or of textiles.