DE4102743A1 - PHOSPHATE-FREE DETERGENT - Google Patents

Abstract

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

Description

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 fertilize.

As is well known, machine cleaning of dishes is known as cleaning middle mixtures used, consisting essentially of inorganic salts, such as alkali phosphates, alkali silicates and alkali carbonates and from Ak tivchlortragen exist and to improve the wetting effect optionally also contain small additions of nonionic surfactants. These mixtures have a good cleaning ability against all types Soiling at the usual working temperatures of 50 to 65 ° C. To prevent thin deposits that develop over time can set off the dish surfaces, and essentially from Starch and possibly protein traces exist and the appearance of the rinsed Crockery may have been significantly affected enzyme-containing dishwashing detergent, as used for example in the DT 17 67 567 are described.

Because of the known environmental influences of the phosphates (water reutrophication) there are still efforts to develop recipes that only contain small and preferably no phosphate. That's the way it is known among other things, phosphates by various organic complexing agents to replace, which also serve as framework substances and for example wise include ethylenediaminetetraacetic acid and the like. But also egg Few of these connections repeatedly trigger environmental discussions as they are not biodegradable and are not eliminated in the sewage treatment plants will.  

Strongly alkaline cleaning agents with no phosphate content, based only of caustic alkalis have a relatively strong cleaning power against all types of soiling, but you have to increase one Accept corrosion effects against glass and onglaze decorations.

DE 24 35 479 A1 already discloses phosphate-free dishwashing agents 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 have an average molecular weight of about 1000 to 20,000. Similar cleaning agents are known from EP 2 67 371 B1 which, as alkali silicate, are a crystalline, layered sodium disilicate of the general formula Na M Si _x O _{2x + 1 .yH 2} O, in which is also suitable for water softening according to DE 34 13 571 A1 the M is sodium or hydrogen, x is a number from 1.9 to 4 and y is a number from 0 to 20, and, as a supplementary structural substance, contain a polymeric and / or copolymeric carboxylic acid or a salt of this polymeric carboxylic acid and active chlorine carrier. The water-free, crystalline layered sodium disilicates used there have been produced thermally, as described in EP 2 93 640 A2. The delta modification of the silicate (δ- Na ₂ Si ₂ O ₅ ) is predominantly obtained.

Crystalline disilicates with the composition Na ₂ Si ₂ O ₅ have also been known from the literature for a long time (cf. JG Vail, Soluble Silicates, Vol. 1, ACS Monograph Series (1952), page 142). The various modifications can be obtained by suitable temperature selection via sintering reactions (cf. A. Willgallis and KJ Range in Glastechnische Beiche 37 (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).

Two factors are known to affect machine performance dishwasher detergents in particular. On the one hand this is the alkalinity of the Reini supply fleet, which must be high enough to swell the leftovers lead and thereby the removal of the dirt residues by the  To support the water mechanics of the dishwasher, and secondly the solubility of the alkali silicates in the liquor as they are the solid help disperse particles and thereby increase the dirt-carrying capacity of the Fleet contribute.

According to the unpublished patent application DE 39 39 919, the β-Na ₂ Si ₂ O ₅ can be obtained from quartz sand and sodium hydroxide solution and / or aqueous solutions of sodium silicates by another 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 δ modification.

In addition, it was surprisingly found that hydrothermally produced β-disilicates have a significantly higher dissolution rate than the δ-disilicate prepared by sintering reactions. It was found that in the β modifications, in comparison to the δ modification, higher proportions of SiO ₂ than Na ₂ O dissolve. Since the β-h modification in turn dissolves particularly quickly, a particularly high proportion of dissolved silicate was observed here.

The present invention is therefore a phosphate-free cleaning agent, in particular for automatic dishwashing, based on crystalline, layered sodium disilicate, alkali metal carbonate, oxidizing agents and optionally alkali metal silicates, surfactants, enzymes and polymeric compounds, which is characterized in that it contain hydrothermally produced Na disilicate of the formula β-h-Na ₂ Si ₂ O ₅ 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.

As alkali carbonates, preferably anhydrous, but also crystal water-containing compounds are used. Sodium carbonate and sodium hydrogen carbonate are preferred, the amounts of which are 3 to 30, preferably 6 up to 15 wt .-%, based on the finished agent.  

Impurities that are particularly difficult to remove, such as stoved food Leftovers, lipstick and tea stains can be useful of oxidizing agents such as active oxygen or active chlorine splitting Ver Require bonds or enzymes in the detergent mixtures.

Active oxygen-releasing Ver are preferably used as oxidizing agents bindings used. As such, the known alkali perborates, -persulfate and -percarbonate are used by activators such as as tetraacetylenediamine, tetraacetylglycoluril, pentaacetylglucose or Diacetyldioxohexahydrotriazine can be activated, but also verbin such as magnesium monoperphthalate, with no activator added can be. Their amounts can be 5 to 10, preferably 6 to 9% by weight, based on the finished product.

Examples of compounds which release active chlorine are those Trichloroisocyanuric acid or its alkali salts, e.g. B. Potassium dichloroisocyanurate, sodium dichloroisocyanurate dihydrate into consideration. Alkali hypochlorites such as lithium or sodium hypo can also be used chlorite, as well as hypochlorite-containing complex salts, e.g. B. so-called chlorinated phosphates.

Suitable enzymes are made from animal and vegetable materials, ins especially obtained from digestive ferment, yeast and bacterial strains. They usually represent a complex mixture of different ones enzymatic active ingredients. Of particular interest are starch, protein or fat-cleaving enzymes such as amylases, proteases and lipases. The En zymes are made from bacterial strains, Pil zen, yeast or animal organs. Most of the time it is there at around enzyme mixtures that have a combined effect, especially against Have starch and protein. The enzyme obtained from Bacillus subtilis preparations are relatively resistant to alkalis and are used by Tempe temperatures between 45 and 70 ° C not yet inactivated, so that they are particularly suitable for use in dishwasher detergents own.  

The enzymes are supplied by the manufacturers, if necessary with the addition of Blending agents such as sodium sulfate, sodium chloride, alkali phosphates or Alkali polyphosphates, set to a certain level of activity. The usual data are in LVE / g (Löhlein-Volhard units per gram), IU (International units) and DE / g (Delft units per gram) for proteolytic enzymes. Because of the simple method of analysis, there are many the activity is given in LVE / g. In the dishwasher according to the invention the proteolytic enzyme activity should average 100 to 5000, preferably 200 to 2000 LVE / g. The amylolytic activity is generally mean in SKB / g (Sandstedt-Kneen-Blish units per gram). they should in the detergent mixture about 5 to 1000, preferably 15 to 250 SKB / g be. The amount of those to be used in the dishwashing detergents Enzyme follows 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. 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 C ₁₀ - to C ₂₀ -, can be used as nonionic surfactants. preferably C ₁₂ to C ₁₈ fatty alcohols, each of which can be end-capped with C ₁ to C ₄ n-alkyl radicals, 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 residues can be used in the molecule.

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

If the cleaning agents foam too much during use, them still 0.1 to 6, preferably 0.5 to 4 wt .-% of a foam-suppressing Compound, preferably from the group of paraffins, hydrophobized Silicic acid and bisstearic acid amides can be added. To be favoured also polymers, especially polycarboxylates, used as co- Builders work. Polyacrylic acids and copolymers come into consideration Maleic anhydride and acrylic acid and the sodium salts thereof  Polymeric 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 ingredients mentioned, the mixtures claimed can be white tere components, especially inorganic salts, the sodium sulfate or Sodium chloride, included as an extender. Other possible additives are buffering substances, dyes, perfumes, as well as given if enzyme-activating additives, such as ammonium chloride or the like.

Insofar as the claimed agents are in powder form, they are confectioned tionation in a known manner by grinding and mixing the stock parts. In order to achieve an intimate connection of the powder components, it may be appropriate to use the powder during the mixing process or during close it with an aqueous solution of crystallizing salts, e.g. B. Sodium sulfate, or one of the nonionic surfactants mentioned hen. Through this treatment, the tendency of the powder to Dusts reduced.

The claimed cleaning agent combinations are characterized by high cleaning ability. They are particularly suitable for being burned to remove protein-containing food residues, traces of lipstick and tea stains. As far as the mixtures contain enzymes, they are able to form them prevent starch deposits on the tableware surfaces or already dismantle existing coverings. Of particular note is the ge rings corrosion effect of the claimed mixtures, especially with por cell glass decor. Finally, the greatly reduced and preferably missing phosphate content of the possible danger of an un desired reutrophication of water prevented.

The claimed funds can be found in both domestic dishwashers as used in commercial dishwashers. The addition takes place by hand or using suitable dosing devices. Particularly suitable the liquid concentrates for use in automatic rivers sigdosing devices, as they are already in use in many cases are. The application concentrations in the cleaning liquor are approximately  0.5-10 g / l, preferably 2-5 g / l, as far as it is solid or powder mixtures.

The rinse program is generally followed by some on the cleaning cycle following intermediate rinse cycles with clear water and a rinse cycle with supplemented with a common rinse aid and finished. After drying you get a completely clean and hygienic one Dishes.

Experimental part

The following silicates were used:

• I: δ-Na₂Si₂O₅, the sintering reaction according to EP-A2-2 93 640 was produced;
• II: β-t-Na₂Si₂O₅, which via a sintering reaction according to Willgallis (60 hours, 600 ° C, 20% crystal seeds) was prepared;
• III: β-h-Na₂Si₂O₅, the hydrothermal reaction according to DE 39 39 919 was produced.

To determine the dissolution behavior of the disilicates, 250 mg (1.37 mmol) 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 Na ₂ O and SiO ₂ . The results are shown in Table 1 below. It should be noted that one mole of disilicate can release one mole of Na ₂ O and two moles of SiO ₂ . The higher dissolving rate of the hydrothermally produced β-h-disilicate, compared to the disilicate obtained via temperature sintering reactions, is striking. In all three types of silicate, the alkalinity was released faster than the silicate. The β modifications also showed the higher proportion of dissolved SiO ₂ compared to the dissolved Na ₂ O. A particularly high proportion of dissolved silicate was observed in the particularly rapidly soluble β-h modification.

Table 1

Dissolve disilicate in deionized water

The same trends as for demineralized water were observed when the Di silicates observed in hard water. The total amount of disilicate dissolved was lower, however, probably due to the formation of calcium Si the dissolving rate on the surfaces of the crystallites is discontinued. The in water with a calcium hardness of 30 ° d Experiments led to those shown in Table 2 below given measurement results.

Table 2

Dissolve disilicate in 30 ° d water containing Ca ²⁺

Because alkalinity is consumed during the rinsing process, for example due to the saponification of fats, it was of interest which alkali serve the cleaning components after they have been used with alkali. For this purpose, 1% suspensions of the β-h and the δ- Disilicate titrated with 0.1 M HCl solution. The hydrochloric acid was added slowly, and after each addition step was waited until a con had set constant pH. The results are as follows reproduced the table 3.  

Table 3

Titration of disilicates (100 mg substance, 0.1 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 β-h- and δ-Na ₂ Si ₂ O ₅ (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 δ 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 β compound is the more alkaline. Here the differences are more than half a pH level.

Since the β modification after an alkali consumption (when rinsing by Spei due to residues, here simulated by adding acid) is more alkaline, this modification has a surprisingly higher alkali reserve, what should result in a better cleaning result. This was in fact, as the examples below show.

Examples example 1

The constituents of the receptors specified below (amounts in% by weight) were in the ploughshare mixer while spraying water and subsequent Drying converted into granules. The granules were made with the Oxidati mixed up onsmittel.

The cleaning services were carried out in a Bosch SMS dishwasher 6021 determined, whereby as standard (sample C) a commercially available phosphate cleaner was used. The rinsing conditions were like follows: Hard water: 16 ° d, Düsseldorf city water and one Detergent dosage from 30 g to 5 l liquor volume. The soiling were created according to known standard conditions (see Th. Altenschöpfer in "Sei fen, Fette, Anstrichmittel ", 73 (1971), pages 459 to 466), and the visual matching of 4 assessments followed on a scale of 0 to 10 points, with 10 being the best Reini result means.

Detergent compositions

Cleaning performance

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

Example 2

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

The following bulk weights (g / l) were compared to those described in Example 1 Cleaners A and B achieved:

Cleaner A: 740

Cleaner B: 950

Claims (1)

Phosphate-free dishwashing detergent based on crystalline, layered Na disilicate, alkali carbonates, oxidizing agents and possibly alkali silicates, surfactants, enzymes and polymeric compounds, characterized in that it is hydrothermally produced Na disilicate of the formula β- as a crystalline layered Na disilicate contains h-Na ₂ Si ₂ O ₅ .