WO1997009411A1

WO1997009411A1 - Process for producing granulated precursors of low alkalinity detergents

Info

Publication number: WO1997009411A1
Application number: PCT/EP1996/003730
Authority: WO
Inventors: Jürgen Härer; Peter Jeschke; Thomas Holderbaum; Frank Wiemer
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1995-09-01
Filing date: 1996-08-23
Publication date: 1997-03-13
Also published as: DE59603641D1; DE19532304A1; EP0848750B1; EP0848750A1; ES2140894T3

Abstract

A process is disclosed for producing granulated precursors of low alkalinity detergents for dish-washing machines that consist of alkaline metal salts of carboxylic acid and organic polycarboxylic acids, so as to counteract the segregating tendency of the finished product. For that purpose, a partial amount of polycarboxylic acid salts is prepared in the usual way, then alkaline carbonate is reacted with the free polycarboxylic acids and their salts, and alkaline hydrocarbonate, at temperatures below 60 °C and in the presence of 2 to 12 % by weight water and the alkaline metal salts of the polycarboxylic acids.

Description

"Process for the Production of Granular Precursors of Low-Alkaline Cleaning Agents"

The invention relates to a process for the production of granular preproducts of low-alkaline cleaning agents which are distinguished by improved grain resistance and lower fine-grain fractions and which can be packaged in the customary manner to lower-alkaline cleaners for machine dishwashing.

From Japanese application JP-A-1-146998 (Matsushita Electric Industrial Co.) a cleaning agent for use in dishwashers is known which contains 1 to 30% by weight of a peroxy compound and 10 to 30% by weight. Contains oxo acid salts and / or aminopolycarboxylic acid salts and is phosphate-free. An advantage of this composition is that low pH is combined with the absence of chlorine compounds. Nothing is described in the Japanese application about the production and grain structure of these agents. The applicant's German patent application DE 42 32 170 AI describes a weakly alkaline agent for machine dishwashing, in which sodium citrate, sodium hydrogen carbonate, a bleach, a bleach activator and enzymes are contained as essential components, and that in 1% by weight aqueous solution has a pH of about 8 to 10. The agents mentioned there are granular. However, detailed information on the production is not included.

The European application EP 414 197 (Beckiser) claims a machine dishwashing detergent which contains at least 25% by weight of a combination of sodium carbonate and sodium hydrogen carbonate, is free of metasilicates, is free of chlorine bleaching agents and in 1% by weight aqueous solution has a mildly alkaline pH of less than 10.5. A further component can be a Acrylic acid-maleic acid copolymer may be present as the sodium salt. It can only be gathered from the preparation of the compositions that they are formulated in the conventional manner as dry powders or granules.

From European patent application EP 530 635 (Benckiser) it is known to produce a liquid or powdery, phosphate-free automatic dishwashing detergent containing a builder system in which a pH value of 5 to 9 is achieved in a 1% by weight aqueous solution and which contains a builder system from the salt of a hydroxycarboxylic acid, or the mixture of a hydroxycarboxylic acid and the salt of a hydroxycarboxylic acid or the mixture of a hydroxycarboxylic acid and the salt of a hydroxycarboxylic acid and a polymer. This patent application also contains no specific information on the manufacture of the products.

Finally, the applicant's German patent application DE-A-4228786 describes a dishwashing detergent with a selected builder system which is said to be solid, lower-alkali, phosphate and chlorine-free and, in addition to an organic water-soluble builder, contains alkali carbonate, oxygen-based bleaching agents, surfactants and other conventional constituents , wherein the builder component contains oxidation products of polyglucosans and / or their soluble salts. For the production, a mixing granulation process is disclosed in which the builder component is mixed and granulated in a mixture with at least one further component in the presence of a liquid.

Low-alkaline detergents for machine dishwashing of the aforementioned type have become increasingly important on the market in recent years. The reason for this is that the products can be handled at a high level of performance without the risk of burns.

Granulation processes are generally used in the production of these products. It has been shown here that it is difficult in technical terms to obtain stable, uniform granules with a small proportion of fines. This applies in particular to products based on the alkali metal salts of carbonic acid and alkali metal salts of polycarbonates. The reason for this is that the alkali metal salts mentioned, especially the sodium salts, such as soda, sodium bicarbonate and sodium nitrate, to name the most important raw materials of this class, are comparatively coarse-crystalline substances that are difficult to bake into a solid grain in a granulation process. Citrate in particular is difficult or cannot be granulated with the other constituents soda and bicarbonate. So that in the actual sense of the granulation process of these constituents, no homogeneous granules of citrate, soda and bicarbonate are produced, but rather more or less in homogeneous mixtures, the homogeneity of which depends above all on the particle size distribution of the raw materials used. However, this is extremely unfavorable for product homogeneity. From an economic point of view, in particular for reasons of cost, however, raw materials of the most varied particle size distribution must be able to be processed.

The granule grains therefore disintegrate, especially during long transport and shaking, which leads to individual constituents in the form of fine particles, segregated, collecting on the bottom of the pack and thus, in addition to problems of recipe constancy due to segregation processes, also one which is not desired by the consumer Deliver the appearance of the product.

The invention seeks to remedy this; it is based on two findings. On the one hand, it was observed that stable, low-particulate granules can be obtained when the alkali metal salts of polycarboxylic acids are prepared in situ from alkali carbonates under mixing and granulating conditions. Furthermore, the knowledge was gained that alkali carbonates, in particular sodium carbonate, in the presence of water can be converted economically into hydrogen carbonates and salts of polycarboxylic acids if the alkali metal carbonates are mixed with a proportion of the alkali metal salts of the polycarboxylic acids right at the start of the reaction.

The great advantages of the process according to the invention are not fully understood scientifically, but it can be speculated that the better granulation behavior is due to the formation of smaller crystals which may have grown together and that the effect of the polycarboxylic acid alkali metal salts on the reaction of alkali metal carbonates with the Acids in the broadest sense can be understood as a buffer effect.

The invention thus relates to a process for the preparation of granular precursors of low-alkali detergents for automatic dishwashing, consisting of alkali metal salts of carbonic acid and organic polycarboxylic acids, characterized in that a partial amount of the salts of polycarboxylic acids is prepared in a customary manner, then in In the presence of 2 to 12% by weight of water, alkali metal carbonate in the presence of the alkali metal salts of the polycarboxylic acids with the free polycarboxylic acid to give their salts and essentially alkali metal bicarbonate at temperatures below 60 ° C.

The invention furthermore relates to a granular precursor of an automatic dishwashing detergent, comprising 20 to 70% by weight of trisodium citrate dihydrate, 20 to 60% by weight of sodium bicarbonate, 0 to 10% by weight of sodium carbonate and 0 to 4% by weight of nonionic An intimate mixture of surfactants, produced by the process according to the invention.

In the process according to the invention, alkali metal salts of carbonic acid and of polycarboxylic acids are used. The sodium salts of carbonic acid such as sodium carbonate (soda, anhydrous or in hydrated form) and sodium hydrogen carbonate are preferably used. The sodium salts are also preferred for the salts of the polycarboxylic acids. A particularly preferred polycarboxylic acid is citric acid, a particularly preferred salt is trisodium citrate, in particular trisodium citrate dihydrate. However, other polycarboxylic acids, for example malic acid, tartaric acid, nitrogen-containing polycarboxylic acids, such as ethylenediaminetetraacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid or triethylenetetraaminehexaacetic acid, methylglycinediacetic acid and the like, can also be used. The oxidation products of polyglucosans mentioned in DE-A-4228 786 can also be used. It is also possible to use copolymers of polymerizable acids, if desired copolymerized with esters and sulfonic acids. So especially copolymers based on acrylic acid-maleic anhydride, acrylic acid Maleic anhydride-vinyl acetate (saponified to vinyl alcohol), methacrylic acid-maleic anhydride and the like.

In terms of the quantity structure, the granular precursors have the following composition: 20 to 70% by weight of polycarboxylic acid alkali salt, 20 to 60% by weight of alkali metal bicarbonate, 0 to 10% by weight of alkali metal carbonate, further constituents, such as tensides, for example from 0.1 to 10, but preferably only up to 5 and in particular only up to 4% by weight can be present.

The person skilled in the art can select the recipe components so that agents are obtained which have a pH in the range of 1% by weight between 7 and 11, in particular 8 and 10 and in particular 8 to 9.

The process according to the invention is carried out in such a way that the alkali metal salt of a polycarboxylic acid is prepared in a conventional manner in a first stage. This can be done by reacting the polycarboxylic acid, for example with an alkali metal hydroxide solution, alkali metal bicarbonate or alkali metal carbonate. In a second stage, the alkali metal carbonate, for example sodium carbonate, is then reacted with the polycarboxylic acid, for example citric acid, to alkali metal bicarbonate and the salt of the polycarboxylic acid in the presence of this amount of polycarboxylic acid salt. This reaction takes place in the presence of small amounts of water, namely 2 to 12% by weight, preferably 3 to 8% by weight of water.

A number of alternatives are available to process engineers for practicing the invention. For example, the salt of polycarboxylic acid can be placed in a mixer, granulator or the like, and then the other constituents can be added continuously or in portions in the presence of the amount of water.

According to a further embodiment, it is also possible to work in a continuous mixer in which the amount of Polycarboxylic acid salt the other substances and the water are added continuously.

It is also possible to work in such a way that all the solids are placed in a granulation mixer and the reaction is then started by adding water.

In the process according to the invention it may be preferred to carry out the reaction under conditions which are so gentle that a large part of the alkali metal carbonate is converted into hydrogen carbonate and the sodium salt of polycarbonate acid. If one works under drastic conditions, for example under heating or in the presence of only small amounts of polycarboxylic acid salt, alkali carbonate and free CO2 are formed to a substantial extent instead of hydrogen carbonate.

In the context of the method according to the invention, the gentle procedure is preferred, this applies in particular if, for the sake of simplicity, the reaction is not carried out in a separate reactor, but rather as a solid reaction in the disperse phase with a high solid content in a mixer with simultaneous granulation.

The mixer has the task of allowing the reaction to proceed to completion by intimately mixing the residues and to build up a granular grain, possibly by adding further granulation aids such as surfactants and polycarboxylate solutions. Mixers that are suitable for granulation and in which residence times of 1 to 10 minutes can be set were therefore used.

Suitable mixers are e.g. B. Eiri mixers of the R or RV series, manufactured by Maschinenfabrik Gustav Eirich, Hardheim, Germany, the Fukae (R) FS-G mixer, manufactured by Fukal Powtech Kogyo Co., Japan the Lödige (R) FM, KM and CB mixer, manufactured by Lödige Maschinenbau GmbH, Paderborn, Germany or the Drais (R) series T or KT, manufactured by Drais Werke GmbH, Mannheim, Germany. In a particularly preferred embodiment of the process, soda is used as the alkali carbonate and sodium tricitrate-2-hydrate as the polycarboxylic acid salt. The acid is then worked with citric acid and sodium bicarbonate is obtained in an intimate mixture with sodium tricitrate dihydrate and, if desired, small amounts of soda.

The amount by weight of polycarboxylic acid sodium salts which is quasi introduced into the reaction as a buffer can be freely determined by the person skilled in the art, based on the amount of soda it is 10 to 500% by weight, preferably 50 to 150% by weight, based on alkali carbonate .

The process according to the invention is controlled so that the residual alkali carbonate content is less than 20% by weight, preferably less than 10% by weight and in particular less than 5% by weight. Low alkali carbonate contents with a high amount of hydrogen carbonate can be achieved by specifying 50 to 150% by weight, based on alkali carbonate, of polycarboxylic acid salts and working under mild temperature conditions. Higher levels of alkali carbonate, with less hydrogen carbonate, can be achieved either by working at higher temperatures or by starting with lower amounts of the salts of the polycarboxylic acids.

However, it is also possible for the person skilled in the art to produce alkali carbonate from alkali metal bicarbonate in a post-drying step in the process according to the invention. This happens in particular when the temperature is raised to or above the decomposition point of the sodium hydrogen carbonate. For example, in a subsequent drying step, for example in a fluidized bed dryer, the amount of alkali carbonate can be increased at the expense of the amount of alkali hydrogen carbonate, for example at temperatures from 50 to 150 ° C., particularly 100 ° C. to 150 ° C.

Surfactants can also be used as further constituents in the process according to the invention. The total surfactant content of the compositions is generally between 0.5% by weight and 8% by weight and can preferably be 0.8 to 5% 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. Cg_i3_alkylbenzosulfonates, olefin sulfonates, esters and alpha sulfo fatty acids or alpha sulfo fatty acid disalts are used, for example, as surfactants of the sulfonate type. Suitable surfactants of the sulfate type are the sulfuric acid monoesters from primary alcohols of natural or synthetic origin, ie from C - ^ - lδ'fatty alcohols ° or ^from Cιo-20 ~ 0x ° alcohols, and those 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 with 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 completely water-soluble, are also important, especially when they are used together with water-soluble nonionic or anionic surfactants. In addition, nonionic surfactants made from alkyl polyglycosides of the general formula R-0- (G) _x can be used, in which R denotes a primary, straight-chain or branched aliphatic radical having 8 to 22, preferably 12 to 18, carbon atoms, G stands for a glycose unit 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, polymaleinates or copolymers of acrylic acid with maleic acid or maleic anhydride. Such substances are preferably completely absent from the agents according to the invention. The solid dishwashing detergents produced by the process according to the invention can also contain up to 10% by weight of further alkalizing agents. These include in particular the alkali silicates. Preferred alkali silicates are the sodium silicates, in particular the amorphous sodium silicates with a molar ratio Na2θ: Siθ2 of 1: 1.5 to 1: 2.5. Such amorphous alkali silicates are commercially available, for example, under the trade name Porti1 (R). Compounds of alkali silicates and soda, as are commercially available, can also be used.

The process products of the process according to the invention are in particular as granular precursors for the production of cleaning agents for. machine dishwashing. As a rule, they do not contain any oxidizing agents, nor do they contain the components, some of which are sensitive in terms of quantity, that are present in machine dishwashing detergents. In order to produce automatic dishwashing detergents from the products, they can be mixed or granulated with these remaining constituents to give the end products. These remaining ingredients include primarily bleach and bleach activators.

Among the compounds which serve as bleaching agents and deliver H2O2 in water, the sodium perborate tetrahydrate and the sodium perborate monohydrate are of particular importance. Further bleaching agents that can be used are, for example, peroxycarbonate (Na2CO3. 1.5 H2O2) or persic acid 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 organic peracids with H2O2, preferably N, N'-tetraacylated diamines such as N, N, N ', N'-tetraacetylethylene diamine.

The preliminary products are usually mixed with the bleaching agents and other constituents in amounts of about 7: 3 to 9: 1. The oxygenated oxidizing agent content of the ready-made dishwashing detergent 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. up to 5% by weight of a bleach activator. In addition to the bleaching agents and bleach activators mentioned, other active ingredients which are usually only present in small amounts can be added to the precursors according to the invention. These substances are preferably used in amounts of 5 to 10% by weight, based on the finally produced cleaning agent. These small components include, for example, 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 on carriers in a conventional manner and / or embedded in Hü11 substances and are preferably used in amounts not exceeding 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, for example those composed of silicones and paraffins or waxes. These foam inhibitors are preferably bound to a granular, water-soluble or dispersible carrier substance.

Other substances that can be used here are silver protection agents. These are, in particular, inorganic transition metal salts, e.g. B. manganese salts such as manganese sulfate, potassium hexafluorotianate and the like, inorganic transition metal complexes, nitrogen-containing heterocycles such as benzotriazole or isocyanuric acid, natural amino acids such as cystine, histidine, methionine, reversible organic redox systems such as quinone / hydroquinone and / or reversible inorganic ⁺ redox systems Fe3 ⁺ .

The preliminary products produced by the process according to the invention can further be processed into tablets. For this purpose, the preliminary products are mixed with the other constituents mentioned in a mixer and as a mixture using conventional tablet presses, for example eccentric presses or rotary presses, with pressures in the range of 200. 10 ⁵ Pa to 1 500. IO ⁵ Pa pressed. In this way, tablets are obtained which are unbreakable but nevertheless dissolve sufficiently quickly under conditions of use and have bending strengths of normally above 150 N. A tablet produced in this way preferably has a weight of 15 g to 40 g, in particular 20 g to 30 g, with a diameter of 35 mm to 40 mm.

The granular detergent precursors produced by the process according to the invention are stable granules, they show a low proportion of fine matter and can be built up in a favorable manner, in particular with the other constituents mentioned. Granulate to homogeneous, non-segregating cleaning agents.

A particular advantage of the process according to the invention is that only very small amounts of carbon dioxide are produced in the neutralization and granulation step. It is shown, for example, by the surprisingly high bulk weights (bulk weights over 900 g / l can be generated), which in turn shows that the process products are not inflated by CO2.

Examples

In a Drais PMH 12.5 Tex mixer, the following batches were processed into a granular intermediate:

Example # 1

kg kg kg

Cß / Cio alkyl polyglcycoside, DP approx.1.435% aqueous solution 0.17 0.17 0.17

C12 C14 fatty alcohol, 4 EO 0.08 0.08 0.08

Cχ2 C14 fatty alcohol, 10 E0 butyl ether 0.03 0.03 0.03

Trisodium citrate 2 H20 (TNC) 2.48 2.48 2.48

Soda calc. 2.23 2.96 2.23

Sodium bicarbonate 3.11 2.37 3.11

Citric acid 1 H2O (Z5-H3) 1.87 1.87 1.87

In Examples 1 and 2, TNC, sodium carbonate and citric acid were introduced, neutralized with the addition of water while the mixer was running and granulated after addition of bicarbonate, the surfactants and a second amount of water. Example No. 3 differs from Example 1 only in that bicarbonate was initially introduced. According to the two possible parallel reactions, a favored formation of CO 2 is to be expected:

1.5 Na ₂ CO 3 + ZS-H3-ZS-Na ₃ + 1.5 NaHCO ₃ (I)

3 NaHCθ3 + ZS-H ₃ -ZS-Na ₃ + 3H2θ + 3Cθ2 (II)

The granules thus obtained were dried in a fluidized bed dryer. The following amounts of CO2 were generated during the granulation:

Example No. 1 2 3

CO2 (kg) 0.44 0.36 0.43

C0 ₂ (%) 4.4 3.6 4.3

The percentages are based on the batch amount and surprisingly low despite the high amounts of bicarbonate present in Example 3 in the neutralization step.

Claims

claims

1. A process for the preparation of granular precursors of low-alkaline cleaning agents for automatic dishwashing, consisting of alkali metal salts of carbonic acid and organic polycarboxylic acids, characterized in that a subset of the salts of polycarboxylic acids is prepared in a conventional manner, then in the presence of 2 to 12% by weight .-% water, alkali metal carbonate in the presence of the alkali metal salts of the polycarboxylic acids with the free polycarboxylic acid to their salts and essentially alkali metal bicarbonate at temperatures below 60 ° C.

2. The method according to claim 1, characterized in that the reaction is carried out with simultaneous granulation of the components.

3. Process according to claims 1 and 2, characterized in that the reaction is carried out in a mixer suitable for granulation and dwell times of 1 to 10 minutes are set.

4. Process according to claims 1 to 3, characterized in that the amount of the salts of the polycarboxylic acids is 10 to 500 wt .-%, preferably 50 to 150 wt .-% of the amount of alkali carbonate.

5. Process according to claims 1 to 4, characterized in that the polycarboxylic acid or its sodium salts, in particular trisodium citrate, is used and that soda is used as the alkali carbonate.

6. The method according to claims 1 to 5, characterized in that the amount of soda to a residual content of 20 wt .-% (based on the total amount) preferably 10 wt .-% and in particular 5 wt .-% to the Poly¬ carboxylic acid salt and sodium hydrogen carbonate is implemented.

7. The method according to claims 1 to 6, characterized in that sodium hydrogen carbonate is then converted, at least partially, by heating to sodium carbonate.

8. The method according to claims 1 to 6, characterized in that the heat treatment is carried out in a fluidized bed dryer.

9. The method according to claims 1 to 8, characterized in that surfactants, in particular nonionic surfactants, such as alkyl polyglycosides and / or alkoxylation products of long-chain alcohols with 2 to 10 moles of ethylene oxide per mole of alcohol are used as further constituents.

10. The method according to claims 1 to 9, characterized in that the substance mixtures are finished in a manner known per se by adding peroxy compounds and other components customary in machine dishwashing detergents, such as silver preservatives, dyes, fragrances and the like.

11. The method according to claims 1 to 9, characterized in that the mixtures of substances in a manner known per se with other, in machine dishwashing detergent ingredients to pieces, in particular tablets, pressed.

12. The method according to claims 1 to 11, characterized in that the ratio of soda, sodium bicarbonate and in salts of polycarboxylic acids is chosen so that the agent in a 1 percent solution has a pH of 7 to 11, preferably 8 to 10, exhibit.

13. Granular precursors of an automatic dishwashing detergent, containing 20 to 70% by weight of trisodium citrate dihydrate, 20 to 60% by weight of sodium hydrogen carbonate, up to 10% by weight of sodium carbonate and 0 to 4% by weight of nonionic surfactants Mixture produced according to claims 1 to 12.