WO1992013935A1

WO1992013935A1 - Phosphate-free cleaning agent

Info

Publication number: WO1992013935A1
Application number: PCT/EP1991/002452
Authority: WO
Inventors: Wilfried Schirmer; Johannes Hachgenei; Günther Just; Winfried Wichelhaus
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1991-01-30
Filing date: 1991-12-19
Publication date: 1992-08-20
Also published as: EP0569365A1; DK0569365T3; EP0569365B1; ES2068702T3; DE59104641D1; ATE118539T1; DE4102743A1

Abstract

Disclosed is a phosphate-free dishwashing agent containing crystalline sodium disilicate ($g(b)-form) produced hydrothermally from quartz sand and caustic soda by a sintering process.

Description

"Phosphate-free cleaning agent"

The invention relates to a phosphate-free cleaning agent, in particular for machine cleaning of dishes, based on crystalline layered Na disilicates, alkali carbonates, oxidizing agents and optionally alkali silicates, surfactants, enzymes and polymeric compounds.

For the machine cleaning of dishes, it is known that cleaning agent mixtures are used which essentially consist of inorganic salts, such as alkali phosphates, alkali silicates and alkali carbonates, and of active chlorine carriers and which, if necessary, contain small amounts of nonionic surfactants to improve the wetting effect. These mixtures have good cleaning properties against all soiling at generally customary working temperatures of 50 to 65 ° C. Enzyme-containing dishwashing detergents, such as those described in, for example, have been used to prevent thin deposits that can settle on the surface of the dishes over time and that consist essentially of starch and possibly traces of protein, and which can significantly impair the appearance of the washed dishes DT 1 767 567.

Because of the known environmental influences of the phosphates (water reutrophication), efforts are still being made to develop recipes which contain only small and preferably no phosphate components. It is known, among other things, to replace phosphates with various organic complexing agents which also serve as framework substances and which include, for example, ethylenedia intetraacetic acid and the like. However, some of these compounds also repeatedly trigger environmental discussions, since they are not biodegradable and are not eliminated in the sewage treatment plants. Strongly alkaline cleaning agents without phosphate content, based solely on caustic alkalis, have a relatively strong cleaning power compared to all types of soiling, but you have to accept an increased corrosion effect against glass and onglaze decorations.

DE 2435479 A1 already discloses phosphate-free dishwashing detergents with reduced corrosion activity, which essentially consist of water-soluble alkali silicates and water-soluble organic complexing agents, such as the water-soluble alkali salts of polyacrylic acid, which has an average molecular weight of about 1000 to 20,000. Similar cleaning agents are known from EP 267 371 B1, which, as alkali silicate, contain a crystalline, layered sodium disilicate of the general formula Na M Si _x θ2 + + ι.yH2θ in which M is sodium or Hydrogen, x is a number from 1.9 to 4 and y is a number from 0 to 20, and also contain a polymeric and / or copolymeric carboxylic acid or a salt of this polymeric carboxylic acid and active chlorine carrier as a supplementary structural substance. The water-free, crystalline layered sodium disilicates used there have been produced thermally, as described in EP 293 640 A2. The delta modification of the silicate (δ ^* - Na ₂ Si2θ5) is predominantly obtained.

In addition, crystalline disilicates with the composition a2Sι ^' 2θs have long been known in the literature (cf. JG Vail, Soluble Silicates, Vol. 1, ACS Monograph Series (1952), page 142). The various modifications can be obtained by a suitable choice of temperature via sintering reactions (cf. A. Willgallis and KJ Range in Glastechnische Reports 31 (1964), pages 194 to 200). The different modifications differ in the corrugation of the silicate layers (see F. Liebau, Acta Cryst., B24 (1968), pages 690 to 699; W. Hoffmann and H.-J. Scheel, Zeitschrift f. Krist., 129 ( 1969), pages 396 to 404).

As is known, two factors particularly affect the performance of machine dishwashing detergents. On the one hand, this is the alkalinity of the cleaning liquor, which must be high enough to lead to the swelling of the food residues and thereby the removal of the dirt residues by the To support the water mechanics of the dishwasher, and on the other hand the solubility of the alkali silicates in the liquor, since they help to disperse the solid particles and thereby contribute to the soiling capacity of the liquor.

According to the unpublished patent application DE 39 39 919, the β-Na2Si2Ö5 can be obtained from quartz sand and sodium hydroxide solution and / or aqueous solutions of sodium silicates in a different reaction path, namely hydrothermally. It was surprisingly found that this hydrothermally produced β-disilicate, hereinafter referred to as β-h-disilicate, leads to better cleaning performance than the fr modification.

It was also surprisingly found that ß-disilicates produced hydrothermally have a significantly higher dissolution rate than the fr-di-silicates produced by sintering reactions. It was found that the β-modifications, compared to the fr-modification, dissolve higher proportions of SiÜ2 than Na2θ. Because the ß-h modification dissolves particularly quickly, a particularly high proportion of dissolved silicate was observed here.

The present invention therefore relates to a phosphate-free cleaning agent, in particular for machine dishwashing, based on crystalline, layered sodium disilicates, alkali metal carbonates, oxidizing agents and, if appropriate, alkali metal silicates, surfactants, enzymes and polymeric compounds, which is characterized in that that it contains hydrothermally produced Na disilicate of the formula Bh-a2Si2θs as a crystalline layered Na disilicate. Any additions of small or very small amounts of alkali phosphates do not lead out of the scope of the invention.

Anhydrous, but also water containing compounds can preferably be used as alkali metal carbonates. Sodium carbonate and sodium bicarbonate, the amounts of which are 3 to 30, preferably 6 to 15,% by weight, based on the finished composition, are preferred. Contaminants which are particularly difficult to remove, such as burnt-on food residues, lipstick and tea stains, may require the appropriate use of oxidizing agents, such as active oxygen or active chlorine-splitting compounds or enzymes in the cleaner mixtures.

Compounds which release active oxygen are preferably used as the oxidizing agent. The known alkali perborates, persulfates and percarbonate can be used as such, which can be activated by activators such as, for example, tetraacetylenediamine, tetraacetylglycoluril, pentaacetylene glucose or diacetyldioxohexahydrotriazine, but also compounds such as magnesium monoperphthalate can be dispensed with, in which case there is no need for activator additives. Their amounts can be 5 to 10, preferably 6 to 9% by weight, based on the finished agent.

Examples of active chlorine-releasing compounds are trichloroisocyanu acid or its alkali metal salts, for. B. Potassium dichloroisocyanurate, Natriu dichloroisocyanurate dihydrate into consideration. Furthermore, alkali hypochlorites, such as lithium or sodium hypochlorite, and hypochlorite-containing complex salts, e.g. B. so-called chlorinated phosphates can be used.

Suitable enzymes are obtained from animal and vegetable materials, in particular from digestive ferment, yeast and bacterial strains. They usually represent a complex mixture of different enzymatic active ingredients. Of particular interest are enzymes that break down starches, proteins or fats, such as amylases, proteases and lipases. The enzymes are produced in a wide variety of processes from bacterial strains, fungi, yeasts or animal organs. Mostly, these are enzyme mixtures which have a combined effect, in particular on starch and protein. The enzyme preparations obtained from Bacillus subtilis are relatively resistant to alkalis and are not appreciably inactivated at temperatures between 45 and 70 ° C., so that they are particularly suitable for use in dishwasher detergents. ≤

The manufacturers set the enzymes to a certain degree of activity, optionally with the addition of blending agents such as sodium sulfate, sodium chloride, alkali phosphates or alkali polyphosphates. The data in LVE / g (Löhlein-Volhard units per gram), IU (international units) and DE / g (Delft units per gram) are common for proteolytic enzymes. Because of the simple analysis method, the activity is often stated in LVE / g. In the dishwashing detergents according to the invention, the proteolytic enzyme activity should be 100 to 5000, preferably 200 to 2000 LVE / g. The amylolytic activity is generally given in SKB / g (Sandstedt-Kneen-Blish units per gram). It should be about 5 to 1,000, preferably 15 to 250, SKB / g in the detergent mixture. The amount of the enzymes to be used in the dishwashing detergents depends on these values.

The foam behavior is decisive for the surfactants that can be used. Low-foam connections are preferred because of the machine mechanics. These are primarily non-ionic surfactants. As nonionic surfactants, all compounds known for this area of application, in particular adducts of 4 to 10 moles of ethylene oxide or 2 to 6 moles of ethylene oxide and 2 to 6 moles of propylene oxide with CIQ- to C20- _» preferably C12- to cig-fatty alcohols, each with Cι ~ to C4-n-alkyl radicals can be end-capped, and alkyl glucosides having 8 to 18, preferably 8 to 14 carbon atoms in the alkyl radical and 1 to 4, preferably 1 to 1.4, glucoside radicals in the molecule are used.

The total amount of surfactants in the cleaning agent is 0.5 to 5% by weight, preferably 1 to 2% by weight.

If the cleaning agents foam too much during use, 0.1 to 6, preferably 0.5 to 4% by weight of a foam-suppressing compound, preferably from the group of paraffins, hydrophobized silica and bisstearic acid amides, can be added to them. Polymers, especially polycarboxylates, which also act as co-builders are also preferably used. Polyacrylic acids and copolymers of maleic anhydride and acrylic acid and the sodium salts thereof are suitable Polymer acids. Commercial products are e.g. B. Sokalan CP 5 and PA 30 from BASF, Alcosperse 175 by 177 from Alco, LMW 45 from NorsoHAAS.

In addition to the constituents mentioned, the claimed mixtures may contain further components, in particular inorganic salts, which contain sodium sulfate or sodium chloride, as a blending agent. Other possible additives are substances with a buffering action, dyes, perfumes and, if appropriate, enzyme-activating additives, such as ammonium chloride or the like.

If the claimed agents are in powder form, they are prepared in a known manner by grinding and mixing the components. In order to achieve an intimate connection of the powder constituents, it may be expedient to mix the powder with an aqueous solution of crystallizing salts, for example, during the mixing process or subsequently. B. sodium sulfate, or one of the nonionic surfactants mentioned. This treatment also reduces the tendency of the powder to dust.

The claimed cleaning agent combinations are characterized by a high cleaning ability. They are particularly suitable for removing burnt-on protein-containing food residues, traces of lipstick and tea stains. As far as the mixtures contain enzymes, they are able to prevent the formation of starch deposits on the dish surfaces or to remove existing deposits again. Of particular note is the low corrosion effect of the claimed mixtures, particularly in the case of porcelain glass decorations. Finally, the greatly reduced and preferably absent phosphate content prevents the possible danger of undesired water reutrophication.

The claimed agents can be used both in household dishwashers and in commercial dishwashers. They are added by hand or using suitable dosing devices. In particular, the liquid concentrates are suitable for use in automatic liquid metering devices, as are already used in many cases. The application concentrations in the cleaning liquor are approximately 0.5 - 10 g / 1, preferably 2 - 5 g / 1, as far as it is a solid or powdery mixture.

The rinse program is generally supplemented and ended by a few intermediate rinse cycles with clear water and a rinse cycle with a customary rinse aid following the cleaning cycle. After drying you get a completely clean and hygienically perfect dishes.

Trial part 1

The following silicates were used:

I: fr-Na2Sι ^' 2θ5, which was produced via a sintering reaction according to EP-A2-293640;

II: β-t-Na2Sι ^* 2θ5, which was produced by a sintering reaction according to Willgallis (60 hours, 600 ° C, 20% crystal seeds);

III: Bh-Na2Sι ^' 2θ5, which was produced via a hydrothermal reaction according to DE 3939919.

To determine the dissolving behavior of the disilicate, 250 mg (1.37 mol) of the sample substance were dissolved in 50 ml of water (use concentration 5 g / l) and stirred for 10 or 30 minutes at room temperature. After centrifugation, 40 ml of the supernatant solution were titrated for Na2θ and Siθ2. The results are shown in Table 1 below. It should be noted that one mole of disilicate can release one mole of Na2θ and two moles of SiÖ2. The higher dissolution rate of the hydrothermally produced .beta.-h-disilicate, compared to the disilicate obtained via temperature sintering reactions, clearly catches the eye. With all three types of silicate, the alkalinity was released faster than the silicate. The ß modifications also showed the higher proportion of dissolved S θ compared to the dissolved Na2θ soluble ß-h modification, a particularly high proportion of dissolved silicate was observed.

Table 1: Dissolving disilicate in deionized water

Disilicate

ß-h

ß-t

The same trends as for demineralized water were observed when dissolving the silicates in hard water. However, the total amount of disilicate dissolved was lower, since the rate of dissolution is likely to be reduced by the formation of calcium silicates on the surfaces of the crystallites. The tests carried out in water with a calcium hardness of 30 ° d led to the measurement results shown in Table 2 below.

Table 2: Dissolving disilicates in 30 ° d Ca2 ⁺ -containing water

ß-t

Since alkalinity is consumed during the rinsing process, for example due to the saponification of fats, it was of interest which alkali reserves the cleaning components still have after the alkali has been used. For this purpose, 1% suspensions of the β-h and fr disilicate were titrated with 0.1 M HCl solution. The hydrochloric acid was added slowly, and after each addition step was waited until a constant pH had been established. The results are shown in Table 3 below.

Table 3: Titration of disilicate 100m substance, 0.1 M HCl solution)

Both disilicates have practically the same initial pH value and are neutralized after adding the equivalent amount of hydrochloric acid. However, if you compare the titration curves for ß-h- and fr-Na2Si2θ5 (see Fig. 1), you can see that the curve in the alkaline range differs significantly. Up to about half the equivalent amount of acids, the fr modification is the more alkaline compound, the difference in pH compared to the β-h curve being up to an entire pH level. After that, the two curves intersect and the ß compound is the more alkaline. Here the differences are more than half a pH level. Since the β modification after alkali consumption (due to flushing due to food residues, here simulated by adding acid) is more alkaline, this modification has a surprisingly higher alkali reserve, which should result in a better cleaning result. This was actually the case, as the examples below show.

Examples

Example 1:

The constituents of the receptors specified below (amounts in% by weight) were converted into granules in the ploughshare mixer while spraying water and subsequent drying. The granules were mixed with the oxidizing agent.

The cleaning performance was determined in a Bosch SMS 6021 dishwasher, using a commercially available phosphate-containing cleaner as standard (sample C). The rinsing conditions were as follows: hard water: 16 ° d, Düsseldorf city water and a detergent dosage from 30 g to 5 1 of fleet volume. The soiling was produced according to known standard conditions (see Th. Altenschöpfer in "Seefen, Fette, Anstrichmittel", 73 (1971), pages 459 to 466), and the visual sampling, which was determined in each case from 4 assessments, was carried out on a scale from 0 to 10 points, 10 being the best cleaning result.

Cleaner compositions

Cleaner A B C

35

Dehypon LS 54 ^R adduct of 5 moles of ethylene oxide and 4 moles of propylene oxide with 1 mole of Ci214 "fatty alcohol

Sokalan ^R CP 5 maleic anhydride-acrylic acid copolymer, Na salt

Cleaning performance

The β-disilicates are preferably used in amounts of 20 to 70, in particular 30 to 60,% by weight.

Example 2:

An important advantage of the ß-h-disilicates used according to the invention is that cleaners with a high bulk density can be produced, which is important for the machine-programmed application. Commercial granular cleaners have liter weights between approx. 900 and 1000 g / 1. With a dosing recommendation and a dosing box volume of 40 ml (customary on the market), there are amounts of detergent of 36 to 40 g per cleaning cycle. When using cleaner A, due to its low liter weight, there is an underdosing of approx. 20% by mass, which is not to be feared when using the inventive cleaners according to B. are. As a result of a too short dosage, deposits can occur in the machine and on the dishes or a poorer cleaning result can be obtained.

The following bulk densities (g / l) were achieved with the cleaners A and B described in Example 1:

Cleaner A Cleaner B 740 950

Claims

1**

Claim

Phosphate-free dishwashing detergent based on crystalline, layered Na disilicates, alkali carbonates, oxidizing agents and possibly alkali silicates, surfactants, enzymes and polymeric compounds, characterized in that it is hydrothermally produced Na disilicate as a crystalline layered Na disilicate of the formula ß-h-Na2Si2θs contains.