EP0656937B1 - Dish-washing products with selected builder system - Google Patents

Abstract

Solid, weakly alkaline, phosphate- and chlorine-free products for dish-washing machines contain organic water-soluble builders, alkali carbonate, oxygen-based bleaching agents, surfactants and if required further usual components. In order to avoid the inconvenient formation of lime deposits in the dish-washing machines used, and in particular on the washed dishes, washing products are disclosed which contain oxidation products of polyglucosanes and/or their soluble salts as builder components.

Description

Agents of the latest phosphate-free generation for the automatic cleaning of dishes contain, in addition to surface-active substances, oxygen-based oxidizing agents and a relatively complex builder combination of alkali carbonates and organic complexing agents. The organic complexing agents used to date include organophosphonic acids, hydroxycarboxylic acids, aminocarboxylic acids and in particular polymeric polycarboxylic acids, which are often used in admixture with low molecular weight polyhydroxypolycarboxylic acids, for example citric acid, or their water-soluble salts. In addition, alkali silicate is usually present as a further builder component. In the international patent application WO-A-91/15568 composite detergents for machine dishwashing in tablet form and a manufacturing process for such tablets are proposed. The method comprises the separate production of a cleaning additive containing polymeric polycarboxylate, sodium carbonate, sodium sulfate and water, which is pressed together with other components, in particular sodium silicate. Detergents composed as described above frequently have the disadvantage, particularly when the water hardness is relatively high, that limescale deposits form, both in the dishwasher used and in particular on the cleaned items. International patent application WO-A-92/01035 relates to a method for producing agents with a high bulk density for cleaning dishes by agglomerating silicate-free builder material, for example phosphate, carbonate or polycarboxylate, with a binder and admixing alkali silicate and bleach. U.S. Patent No. 3,629,121 describes solid phosphate and chlorine free agents which contain nonionic surfactant and oxidation products of polysaccharides, e.g. Dicarboxyl starch containing aldehyde groups. The agents disclosed there lack oxygen-based oxidizing agents.

Surprisingly, it has now been found that by using a builder combination which contains certain oxidation products of polyglucosans, it is possible to inhibit the formation of deposits caused by the dishwashing detergent in conjunction with the hardness constituents of the water.

mit einer, zwei oder drei Carboxylgruppen und/oder deren löslichen Salzen pro Einheit besteht.The invention accordingly relates to a solid, lower-alkaline, phosphate and chlorine-free agent for machine cleaning of dishes, containing organic water-soluble builders, bleaching agents based on oxygen, surfactant and, if desired, other conventional constituents, which is characterized in that it contains 10% by weight. % to 30% by weight of alkali carbonate, 30% by weight to 50% by weight of alkali metal bicarbonate and, as a builder component, 5% by weight to 60% by weight of a polymer made from anhydroglucose units which at least partly consists of oxidized anhydroglucose units of the constitutional formulas I, II and / or III,

with one, two or three carboxyl groups and / or their soluble salts per unit.

Extensive knowledge exists for the production of such polysaccharide derivatives by oxidative treatment of, for example, cellulose, starch and dextrins. Reference is made, for example, to Houben-Weyl, Methods of Organic Chemistry, Thieme-Verlag, Stuttgart (1987) Vol. E20, Macromolecular Substances, here the subchapter "Polysaccharide Derivatives" edited by Dr. K. Engelskirchen, op. Cit. Pp. 2042 ff, in particular pp. 2124 ff (oxidation products of cellulose) and pp. 2166 ff (oxidized starches). Reference is also made to the publication "Cellulose Chemistry and Its Applications" (1983), John Wiley & Sons, Chichester, GB, in particular TPNevell, "Oxidation of Cellulose" (Chapter 10), the extensive literature cited there, loc. Cit. 262 to 265, and to European patent applications EP 425 369, EP 455 522 and EP 472 042.

In a nutshell: A large number of oxidizing agents are used for the oxidation of polyglucosans. Examples include (air) oxygen, hydrogen peroxide, sodium hypochlorite or bromite, periodic acid or periodates, lead (IV) acetate, nitrogen dioxide and cerium (IV) salts. These oxidants react very differently with the anhydroglucose units, cf. for example the formula pictures in Houben-Weyl loc. cit. p. 2124. It is known that when nitrogen dioxide acts on cellulose, the oxidation of the primary alcohol group to the carboxy group is the predominant reaction. The oxidizing agent can be used in gaseous form or dissolved in an inert organic solvent, cf. here also Houben-Weyl aa0. P. 2125 and the primary literature mentioned there in this connection. Starting from the starch, too, largely selective oxidations of the primary alcohol group of the anhydroglucose unit to the carboxy group can be accomplished. The teaching according to the invention is based on this knowledge of the prior art.

For example, monocarboxyl starches with a freely selectable degree of conversion of the primary alcohol groups can also be produced without additives, for example solvents or catalysts, by their selective oxidation with nitrogen dioxide at low temperatures. The almost quantitative and largely selective implementation of the building blocks of the starch molecule is also possible.

However, such a quantitative implementation is not necessary for the purpose according to the invention of using such natural product derivatives as builders in the agents described. Rather, the interaction of the following two parameters is essential: adequate conversion of the primary alcohol groups to carboxy groups and, on the other hand, regulation of the average molecular weight of the natural polyglucosan molecule to sufficiently degraded sections. The first of these two parameters is likely to have functional significance for the interaction with the hardness formers, for example, while the sufficiently restricted average molecular weight of the modified polyglucosan building blocks can be important, among other things, for the sufficient solubility of the builder under operating conditions.

The following applies to these two parameters:

The preferred lower limit for the content of oxidized anhydroglucose units according to formula I, II and / or III is in the polyglucosan derivatives at about 25 mole%, preferably at least about 35 mole% to 40 mole%. The almost quantitative conversion of one, two or three alcohol groups into carboxy groups is possible, so that the upper limit for the corresponding content of oxidized anhydroglucose units is 95 mol% to about 100 mol%. Corresponding oxidation products, which are characterized by contents in the range from approximately 35 mol% to 80 mol% of oxidized anhydroglucose units, can be particularly suitable for practical use, with their content in the range from approximately 40 mol% to 60 in an important embodiment Mol% is.

In the field of starch derivatization in particular, it has been shown that in the course of the oxidative treatment of the dry starch, which usually contains limited amounts of water, with NO ₂ and, if appropriate, conversion of the oxidation products into water-soluble salts, in addition to the largely selective oxidation of the primary alcohol groups, a breakdown of the molecular weight of the starch molecule takes place to such an extent that the resulting derivatized polyglucosans are particularly suitable as builders and give aqueous solutions with viscosities in the range mentioned above.

The statistical average of the oxidized polyglucosans to be used according to the invention preferably consist of at least 15 mol% of oxidized anhydroglucose units of the formula I and have average molecular weights below 15,000.

The builder component in the sense of the definition according to the invention is preferably used in the dishwashing detergents in amounts of 5% by weight to 60% by weight and in particular in the range from 10% by weight to 40% by weight, based in each case on the total weight of the detergents , used. Quantities in the range from 15% by weight to 30% by weight can often be expedient. Both the use in the form of the free carboxylic acid and the neutralized form, in particular the alkali metal salts, are possible. When the free carboxylic acid is used, the alkali salts generally form under the conditions of use.

The composition of the cleaning agents can otherwise be chosen practically arbitrarily in the context of known recipes.

Cleaning agents for dishes according to the invention contain, as main components, surfactants, the builder component in the sense of the invention, peroxy bleaching agents and the usual other dishwashing agent components, such as enzymes, colorants and fragrances, alkalizing agents, such as soluble alkali silicates, and optionally neutral salts and water.

Among the compounds used as bleaching agents in water, H ₂ O ₂ compounds, the sodium perborate tetrahydrate have (NaBO ₂ .H ₂ O ₂ · 3H ₂ O) and sodium perborate monohydrate (NaBO ₂ .H ₂ O ₂₎ are particularly important. Other bleaching agents that can be used are, for example, peroxy carbonate (Na ₂ CO ₃ .1.5 H ₂ O ₂ ) or peracidic salts of organic acids, such as perbenzoates or salts of diperdodecanedioic acid. Suitable bleach activators for these oxidizing agents are in particular the N-acyl or O-acyl compounds which form with H ₂ O ₂ organic peracids, preferably N, N'-tetraacylated diamines such as N, N, N ', N'-tetraacetylethylene diamine. The oxygen-based oxidizing agent content of the dishwashing agents is preferably about 5% by weight to 15% by weight, in particular in combination with 1% by weight to 10% by weight, in particular 2% by weight to 5% by weight. % of a bleach activator.

The total content of surfactants in the compositions is generally between 0.5% by weight and 5% by weight and can preferably be 0.8 to 3% by weight. Usual surfactants for cleaning agents belong to the groups of anionic, nonionic and / or zwitterionic surfactants, the use of anionic and / or nonionic surfactants being preferred. Particularly suitable anionic surfactants are sulfonates and sulfates and soaps made from preferably natural fatty acids or fatty acid mixtures. Examples of surfactants of the sulfonate type used are C _9-13 alkylbenzenesulfonates, olefin sulfonates, esters of alpha-sulfofatty acids or alpha-sulfofatty acid disalts. Suitable surfactants of the sulfate type are the sulfuric acid monoesters from primary alcohols of natural or synthetic origin, ie from C _12-18 fatty alcohols or from C _10-20 oxo alcohols, and those of secondary alcohols of this chain length. The sulfuric acid monoesters of the alcohols reacted with 1 to 6 mol of ethylene oxide (EO) are also suitable.

Addition products of preferably 2 to 20 moles of EO to 1 mole of an aliphatic compound with essentially 10 to 20 carbon atoms from the group of alcohols, carboxylic acids, fatty amines, carboxamides and alkanesulfonamides are of particular interest as nonionic surfactants. In addition to the water-soluble nonionic surfactants, polyglycol ethers with 2 to 7 ethylene glycol ether residues in the molecule, which are not or not completely water-soluble, are also important, especially when they are used together with water-soluble nonionic or anionic surfactants. In addition, alkyl polyglycosides of the general formula RO- (G) _x can also be used as nonionic surfactants, in which R denotes a primary, straight-chain or branched aliphatic radical having 8 to 22, preferably 12 to 18 C atoms, G for a glycose unit is with 5 or 6 carbon atoms and the degree of oligomerization x is between 1 and 10.

In a preferred embodiment, the dishwashing detergents of the invention contain no more than 10% by weight of water-soluble organic complexing agents or co-builders from the group of synthetic polymeric polycarboxylates, which are taken to mean the salts of polymerization products of unsaturated carboxylic acids and which include, for example, polyacrylates, polymethacrylates , Polymaleinate or copolymers of acrylic acid with maleic acid or maleic anhydride belong. Such substances are preferably completely absent from the agents according to the invention. In a further preferred embodiment of the agents according to the invention, further complexing agents such as citric acid or alkali citrates and / or the salts of nitrilotriacetic acid are not present, or at most in quantities not exceeding 30% by weight, in particular not exceeding 10% by weight.

The usual alkalizing agents used in solid dishwashing detergents include, in addition to the alkali carbonates, the alkali silicates. Preferred alkali silicates are the sodium silicates, in particular the amorphous sodium silicates, with a Na ₂ O: SiO ₂ molar ratio of 1: 1.5 to 1: 2.5. Such amorphous alkali silicates are, for example, under the trade name Portil® commercially available. The content of alkali silicates in the agents according to the invention can be up to 30% by weight, based on the anhydrous substance. Amorphous sodium silicate contents in the range below 20% by weight, in particular from 5% by weight to 15% by weight, are preferred. Alkali carbonate and alkali hydrogen carbonate are preferably contained in the agents according to the invention in amounts of 40% by weight.

The previously mentioned other cleaning agent components, which are usually only present in small amounts, can make up in particular up to 20% by weight, preferably 5 to 10% by weight. These small components include, for example, further organic builder components, foam inhibitors and enzymes of the type of proteases, amylases, lipases and / or cellulases and water which is not bound as water of crystallization or is associated with the constituents in a similarly solid form. The enzymes can be adsorbed onto carrier substances in a conventional manner and / or embedded in coating substances and are preferably used in amounts of not more than 5% by weight, in particular 2 to 4% by weight. Suitable non-surfactant-like and preferably used foam inhibitors are organopolysiloxanes and their mixtures with microfine, optionally silanized silica. The foam-inhibiting use of long-chain soaps is also possible. Mixtures of different foam inhibitors can also be suitable, e.g. those made of silicones and paraffins or waxes. These foam inhibitors are preferably bound to a granular, water-soluble or dispersible carrier substance.

The solid, pourable dishwashing detergents according to the invention are preferably in the form of powdery, granular or tablet-like preparations which can be prepared in a conventional manner, for example by mixing, granulating, roller compacting and / or by spray drying.

For the preparation of cleaning agents according to the invention in tablet form, the procedure is preferably such that all the components are in one Mixer mixed together and the mixture is pressed by means of conventional tablet presses, for example eccentric presses or rotary presses, with pressures in the range from 200 · 10 ⁵ Pa to 1 500 · 10 ⁵ Pa. In this way, break-resistant tablets are obtained which, under application conditions, dissolve sufficiently quickly, with bending strengths normally above 150 N. Preferably, a tablet produced in this way has a weight of 15 g to 40 g, in particular 20 g to 30 g, with a diameter of 35 mm up to 40 mm.

The manufacture of machine dishwashing agents within the scope of the invention in the form of non-dusting, storage-stable, free-flowing powders and / or granules with high bulk densities in the range of preferably 750 to 1,000 g / l is characterized in that in a first process sub-stage the builder component mixed with at least a portion of liquid mixture components while increasing the bulk density of this premix and subsequently - if desired after an intermediate drying - the further components of the dishwasher detergent are combined with the premix obtained in this way.

In the first stage of the process, the liquid phase used is, in particular, the surfactant compounds which are liquid under normal conditions - in particular the corresponding nonionic surfactants - and, if desired, further liquid components of the overall formulation. The fragrances dissolved in carrier liquids and / or limited amounts of water or aqueous solutions of mixture components of the desired dishwashing detergent come into consideration here.

In the first sub-stage of the mixing process according to the invention, the builder is generally mixed with at least one further component of the dishwashing detergent with the liquid components. Here, for example, a precursor comes into consideration, in which the builder component in admixture with perborate is acted upon by the liquid nonionic surfactants and the solution of the fragrances and mixed intimately. The remaining components are then added and the entire mixture is worked through and homogenized in the mixing device. The use of additional amounts of liquid, in particular the use of additional Water is usually not required here. The mixture of substances obtained is then in the form of a free-flowing, dust-free powder of the desired high bulk densities, approximately in the range from 800 to 900 g / l.

In another embodiment, greater agglomeration with the formation of heavy agglomerate particles is important. In this case, the use of larger amounts of liquid may be expedient or necessary, in which case even larger amounts of the components to be combined can be subjected to the premixing together with the builder component. Here, for example, the builder component can be mixed with alkali carbonate and at least a portion of the finely divided solid alkali silicate and agglomerated in a densifying manner by adding limited amounts of water and / or aqueous alkali silicate solutions. For example, when working in a Lödige ploughshare mixer with a knife ring, heavy granules with bulk densities in the range of up to 950 g / l are obtained in the mode of operation specified in the examples below.

If water is used as auxiliary liquid in such amounts in the course of this granulation process that residual moisture in the finished product exceeds the range of about 4 to 7% by weight, it may be expedient to subject the pre-granules formed to intermediate drying. Drying in the fluidized bed is suitable for this purpose, for example. As a rule, such a drying treatment with product temperatures in the range of about 80 ° C. for a limited period of time - for example 10 to 15 minutes - is sufficient to set the desired residual moisture in the product within the range of about 4 to 7% by weight.

The pre-granules are then mixed with the missing components of the dishwashing detergent to form the finished product. In all the cases shown here, the mixing time is both in the preliminary stage of the compacting mixture under the influence of liquid components and in the subsequent final mixture with the other components in the range of a few minutes, for example in the range of 1 to 5 minutes.

In a particular embodiment, it can be useful in the production of fine granules by powdering the surface of the formed Granules to set a further stabilization and leveling. Small amounts of water glass powder or powdered alkali carbonate are particularly suitable for this purpose.

Examples Example 1 : Preparation of the oxidized polyglucosans

275.2 g of potato starch (1.6 mol based on anhydroglucose unit) with a moisture content of approx. 6% by weight were suspended in 825 g of carbon tetrachloride and transferred to a 21-stirring autoclave. After the autoclave had been evacuated and flushed with nitrogen, 73.6 g of condensed nitrous oxide (0.8 mol) were added. The reaction mixture was heated to 50 ° C. within 30 minutes. The internal pressure in the autoclave was 0.5 bar (adjusted with nitrogen). By pressing on oxygen, an internal pressure of 2 bar was maintained within the first hour of the reaction, which was raised to 6 bar within the next hour. After a reaction time of 4.5 hours, there was no more oxygen consumption, noticeable from the drop in pressure. The autoclave was cooled to room temperature, decompressed, and 1 l of demineralized water was added to the reaction mixture. The suspension of the oxidation product was filtered through a glass suction filter. The product was first washed with acetone, then with water until the washing liquid had a neutral reaction, dewatered with acetone and dried (70 ° C., vacuum drying cabinet). 256 g of white, powdered polycarboxylate B1 with an acid number of 324 were obtained, corresponding to an average content of about 1 carboxyl group per anhydroglucose unit. The product had a reduced viscosity (η _red ) of 3 ml / g measured on the 2 percent by weight solution of the sodium salt in 1N aqueous sodium nitrate solution at 20 ° C.

Example 2

The raw materials listed in Table 1 below were mixed in the amounts listed there (% by weight, based in each case on the finished product) in a Lödige mixer with a knife ring. The agents M4 to M6 according to the invention were obtained using the polycarboxylate B1 prepared according to Example 1 and, for comparison, the agents M1 to M3 and V1 and V2 not according to the invention. Table 1: Composition of cleaning agents (% by weight) M1 M2 M3 M4 M5 M6 V1 V2 B1 30th 30th 8th 10th 30th 30th - - Na citrate ^a) - - 30th 30th - - 30th 30th Polycarboxylate ^b) 8th - - - 10th - 8th 10th Na disilicate 20th 20th 20th - - - 20th - Na carbonate 30th 38 30th 13 13 13 30th 13 Na bicarbonate - - - 36 36 46 - 36 Na perborate ^c) 7 7 7 5 5 5 7 5 TAED 2nd 2nd 2nd 2nd 2nd 2nd 2nd 2nd Nonionic surfactant ^d) 2nd 2nd 2nd 1 1 1 2nd 1 Enzyme ^e) 1 1 1 3rd 3rd 3rd 1 3rd a) Trisodium citrate dihydrate b) Na poly (acrylate / maleinate) (Sokalan® CP 5, manufacturer BASF) c) monohydrate d) Plurafac® LF 403 (manufacturer BASF) e) 1: 1 mixture of protease (BLAP® 140, manufacturer Biozym) and amylase granules (Termamyl® 60 T, manufacturer Novo)

Example 3

The cleaning performance of the agents according to Example 2 was tested in a dishwasher (Miele G531; Universal 55 program) at doses of 20 g each in 71 water at 16 ° dH in the cleaning cycle (soiling, as in the case of Th. Altenschöpfer, SÖFW 98 (1972) 763 -765, described, tea, milk, minced meat, pudding, fat stick, starch, oatmeal). Agents M4 to M6 according to the invention had a superior cleaning performance, particularly when removing the starch and oatmeal stains, and showed in the case of other stains a cleaning performance comparable to the comparison products V1 or V2 .

In a Bosch S 712 dishwasher (doses of 20 g each in 6.2 l water at 16 ° dH, operating temperature 50 ° C), 50 g of pumpable soiling (mixture of ketchup, gravy, mustard, potato starch, egg yolk, Milk, margarine) the deposit formation was tested over 10 rinse cycles of the agents according to Example 2. On a scale from 1 (= no deposit) to 10 (= very heavy deposit), the agents M4 to M6 according to the invention achieved the values given in Table 2 below for the formation of deposits in the machine (value A ) or the formation of deposits on the wash ware ( Porcelain / glass / cutlery; value B ). In all cases, these values were better than those of the other agents, in particular significantly better than the values for the similarly structured comparative product V2 . Table 2: Formation of deposits using detergents medium Topping A Topping B M1 nb 6.5 M2 6.0 4.5 M3 5.0 3.5 M4 3.5 4.0 M5 5.5 4.5 M6 3.0 3.0 V1 6.5 7.0 V2 6.0 5.8 nb: not determined

Claims (12)

1. A solid, low-alkali, phosphate- and chlorine-free machine dishwashing detergent containing organic watersoluble builder, oxygen-based bleaching agent, surfactant and if desired other typical constituents, characterized in that it contains 10% by weight to 30% by weight of alkali metal carbonate, 30% by weight to 50% by weight of alkali metal hydrogen carbonate and, as builder component, 5% by weight to 60% by weight of a polymer of anhydroglucose units which consists at least partly of oxidized anhydroglucose units corresponding to structural formulae I, II and/or III:

   

   containing one, two or three carboxyl groups and/or soluble salts thereof per unit.
2. A detergent as claimed in claim 1, characterized in that the content of oxidized anhydroglucose units corresponding to formulae I, II and/or III in the polyglucosan derivatives is at least 25 mole-%, preferably at least 35 mole-% and more preferably at least 40 mole-%, the upper limit to the content of these oxidized anhydroglucose units being at around 100 mole-% and, more particularly, 95 mole-%.
3. A detergent as claimed in claim 1 or 2, characterized in that it contains as builder oxidation products of polyglucosans of which - on a statistical average - at least 15 mole-% consist of oxidized anhydroglucose units corresponding to formula I and which have average molecular weights below 15,000 and/or soluble salts thereof.
4. A detergent as claimed in any of claims 1 to 3, characterized in that it contains builders based on the selectively oxidized polyglucosans in quantities of 10% by weight to 40% by weight, based on the total weight of the detergent.
5. A detergent as claimed in claim 4, characterized in that it contains no more than 10% by weight of watersoluble organic complexing agents from the group of synthetic polymeric carboxylates and, preferably, is at least substantially free therefrom.
6. A detergent as claimed in any of claims 1 to 5, characterized in that it contains other complexing agents, such as citric acid or alkali metal citrates and/or the salts of nitrilotriacetic acid, at most in quantities of not more than 30% by weight and, more particularly, not more than 10% by weight, if at all.
7. A detergent as claimed in any of claims 1 to 6, characterized in that it contains

   15% by weight to 30% by weight of oxidation products of polyglucosans,

   40% by weight of alkali metal carbonate and alkali metal hydrogen carbonate,

   5% by weight to 15% by weight of alkali metal perborate and/or percarbonate,

   2% by weight to 10% by weight and, more particularly, 1% by weight to 5% by weight of bleach activator,

   0.5% by weight to 5% by weight and, more particularly,

   0.8 to 3% by weight of surfactant, more particularly nonionic surfactant,

   up to 30% by weight and, more particularly, 5% by weight to 20% by weight of alkali metal silicate,

   not more than 5% by weight and, more particularly, 2% by weight to 4% by weight of enzyme,

   not more than 5% by weight and, more particularly, 0.5% by weight to 2% by weight of fragrance.
8. A powder-form or granular detergent as claimed in any of claims 1 to 7, characterized in that it has an apparent density of 750 g/l to 1,000 g/l.
9. A process for the production of a tablet-form detergent having the composition claimed in any of claims 1 to 7, characterized in that all its constituents are mixed in a mixer and the resulting mixture is tabletted in a tablet press under pressures of 200·10⁵ Pa to 1,500·10⁵ Pa.
10. A process for the production of the detergents claimed in claim 8 in powder form and/or granular form with apparent densities of 750 to 1,000 g/l, characterized in that, in a first process step, the builder component is mixed with at least part of the liquid mixture components, an increase in apparent density being obtained, surplus moisture, if any, is removed and the premix is subsequently combined with the other components of the dishwashing detergent.
11. A process as claimed in claim 10, characterized in that liquid surfactant compounds, more particularly corresponding nonionic surfactants, solutions of fragrances in carrier liquids and/or water or aqueous solutions of mixture components, more particularly aqueous alkali metal silicate solutions, are used as the liquid phase in the first stage of the process.
12. A process as claimed in claim 10 or 11, characterized in that, where the mixture of active substances is granulated, the granules obtained are powdered and spheronized in a final step with powder-form alkali metal silicate and/or alkali metal carbonate.