WO1997036984A1

WO1997036984A1 - PROCESS FOR AUTOMATICALLY ADJUSTING THE pH OF AN AQUEOUS TREATMENT SOLUTION AND SOLID CLEANING AGENTS SUITABLE THEREFOR

Info

Publication number: WO1997036984A1
Application number: PCT/EP1997/001470
Authority: WO
Inventors: Christian Nitsch; Karl-Heinz Maurer; Jürgen Härer
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1996-03-30
Filing date: 1997-03-22
Publication date: 1997-10-09
Also published as: DE19612866A1; DE59706388D1; ATE213266T1; EP0891414B1; ES2172775T3; EP0891414A1

Abstract

The pH of an aqueous treatment solution is to be automatically adjusted from the acid to the alkaline. This is achieved in that the desired acid pH is set in an aqueous bath with the simultaneous or subsequent addition of an ammonia-generating and/or organic carboxylic acid-consuming enzyme and its substrate, whereupon the enzymatic reaction is allowed to continue until the desired final pH is attained.

Description

"Method for automatically shifting the pH of an aqueous treatment solution and suitable solid cleaning agents"

The invention relates to a method for automatically shifting the pH of an aqueous treatment solution from acid to alkaline, which uses an enzymatic reaction. The invention further relates to solid agents, in particular cleaning agents, which are suitable for such a method.

A large number of technical processes and procedures which take place in aqueous liquors are dependent on the pH of the aqueous treatment solution with regard to its kinetics or its result. For example, washing and cleaning processes can be carried out in the alkaline or neutral range, and special cleaning processes can also be carried out in acidic processes. With complex cleaning processes such. B. machine dishwashing, it has been shown that certain stains are treated better in acidic, others better in alkaline. It is generally possible to shift the pH from acid to alkaline during the cleaning process by adding alkalis, but this is associated with handling and metering problems. In cleaning processes in closed devices, e.g. B. Household dishwashing machines would also require additional technical changes. On the basis of these considerations, the manufacturer of cleaning agents has the task of providing products which are automatically subject to a pH shift in aqueous solution.

In the international application WO 95/12657, a cleaning agent for automatic dishwashing is described which, after being added to water, initially has an alkaline pH, but which, after a few minutes, becomes neutral after the slow release of an acid ¬ is pushed. The slow release of the acid is achieved by z. B. citric acid wrapped with a double, poorly soluble coating. A very similar process is described in European patent applications EP 290081 and EP 396287 for bleaching agent compositions.

In automatic dishwashing, a change in the pH is desirable in order to achieve the most complete possible removal of tea stone in addition to the good washing performance of conventional cleaning agents in alkaline. Tea stone is a complex, brown-colored soil composed of water hardness formers and coloring components of the tea. It has proven advantageous to remove tea stone by an acidic pretreatment.

It is therefore an object of the invention to provide a process in which an aqueous treatment solution shifts its pH from acid to alkaline without further dosing of alkali, the elaborate coating of individual components being used for the purpose of delayed release should be waived.

The invention thus provides a process for the automatic relocation ^'tion of the pH of an aqueous treatment solution of the AI Sauern quay, characterized in that the desired acidic starting pH is set in an aqueous liquor, an ammonia-generating and / or an organic-carboxylic acid-consuming enzyme and its substrate are added simultaneously or subsequently, and the enzymatic reaction is then carried out runs to achieve the desired final pH.

The invention furthermore relates to a cleaning agent in solid form

2 to 30% by weight of enzyme and enzyme substrate

1 to 50% by weight of a mixture of an organic polycarboxylic acid and its salt and ad 100% by weight of at least one active ingredient selected from the group consisting of oxygen bleaches, bleach activators, builders, surfactants and special active ingredients.

The method according to the invention makes use of an enzymatic reaction to shift the pH of an aqueous treatment solution. Enzymatic reactions were selected because they run safely, substrate-specifically and with sufficient speed in the temperature and concentration range of interest for cleaning operations.

According to a first preferred embodiment of the invention, urease is used as the enzyme and urea as the substrate. Commercial ureas that can be present as pure protein or as a finished product can be used here. A preferred urease is, for example, a urease from "Jack Beans" that is commercially available from Sigma Chemicals. For industrial use, such enzymes are made from microorganisms or mushrooms, and made into technically manageable granules or liquid concentrates.

It has been shown that when using the urease urea system, an initial pH of not less than 4, preferably> 4.3, should be set. The starting pH can be adjusted by using a buffer system or by adding the appropriate amount of an inorganic or organic acid. Suitable buffer systems are buffer systems based on weak organic or inorganic acids and their salts. A preferred buffer system is the citric acid / alkali citrate system, the components of which are also used as builder components in cleaning agents for automatic dishwashing.

According to a further embodiment of the invention, decarboxylases, in particular oxaloacetate decarboxylase and oxalate decarboxylase, can be used as enzymes and carboxylic acids, in particular also oxaloacetic acid and oxalic acid, can be used as substrates. In these systems too, it is preferred to assume a pH> 3, in particular> 4. The pH value is preferably adjusted here by introducing the enzyme substrate and, if desired, partially neutralizing it with alkali metal hydroxide solution or ammonia or the like.

According to a further embodiment of the invention, an enzyme of the oxidase type (for example oxalate oxidase) is used and oxalic acid or its salts are used as the substrate. Here too, a pH value> 3, in particular> 4, is preferably assumed. It is advisable to adjust this pH with the help of oxalic acid and its alkali or ammonium salts. In practice, this method variant has proven itself either with to work lime-free water or to add dispersants such as polycarboxylic acids or detergent builders to counteract the precipitation of calcium oxalate.

The process according to the invention is preferably carried out at temperatures between 10 and 70 ° C. In individual cases, higher temperatures can also be used for a short time if the enzymes survive without denaturation. In particular, however, work is carried out at temperatures between 20 and 60 ° C, with particular preference between 30 and 40 ° C. In particular, the fact is exploited that the enzyme activity gradually increases due to the heating of the non-preheated water and the corresponding pH value is hereby adjusted with appropriate kinetics.

The process according to the invention is based on an acidic treatment solution. For this purpose, the treatment solution can be made acidic on the one hand with strong or weak inorganic or organic acids. In this process variant, the enzymatic reaction results in a very rapid change in the pH.

However, it is particularly preferred to set the acidic pH at the beginning of the treatment process using a buffer solution. The buffer solutions known to the chemist, which allow a pH value between approx. 3 and below 7, can be used here.

For the purposes of the invention, however, it is particularly preferred to use buffer solutions whose constituents are either suitable as substrates for the enzymatic process or which have an independent effect in the sense of the treatment process. So the buffer solutions z. B. from organic carboxylic acids and their alkali or ammonium salts. When using decarboxylates, it makes sense to use those acids which are attacked by the decarboxylase. When using oxidases (eg oxalate oxidase), a buffer system consisting of the substrate (eg oxalic acid) and its alkali metal salts has proven successful. When using oxaloacetate decarboxylase, one works with oxaloacetic acid and its salts.

In the cases in which the treatment solution whose pH is to be influenced by the method according to the invention is a cleaning solution, it has proven useful to use citric acid and its alkali metal or ammonium salts as a buffer system. As in the previous chapters, the sodium or potassium salts are preferred among alkali salts.

The method according to the invention is suitable for influencing the pH of a large number of treatment solutions. According to one embodiment of the method, this treatment solution contains a dye which is readily soluble in acid and irreversibly absorbs on fibers, synthetic fibers, cotton, wool or even hair in alkaline. Suitable here are, for example, azo dyes with trialkylamonium groups or other dye systems which are known to the person skilled in the art and which have ammonium, sulfonium or phosphonium groups.

According to a further embodiment of the invention, the treatment solution according to the invention to be influenced in pH is a cleaning solution. 1

In this case, the treatment solution contains, in addition to enzyme and enzyme substrate, above all surfactants, often also solubilizers, fragrances and dyes. Suitable surfactants from the class of anionic, cationic, nonionic, ampholytic and zwitterionic surfactants and in particular mixtures of the surfactant classes mentioned are suitable. Polymers or salts can also be added as further constituents for thickening. It is usually preferred to store and portion the detergent as a solid. The solid preparation usually contains: 0.5 to 5% by weight of enzymes, 2 to 25% by weight of enzyme substrate, 20 to 70% by weight of surfactant and the remaining constituents are salts, polymers, dyes, fragrances from 100% by weight. -%. In special cases, 20 to 40% by weight of an abrasive material may still be present at the expense of the other constituents.

Anionic surfactants suitable for the purposes of the invention are, in particular, surfactants from the class of the sulfonates and sulfates. Suitable examples are alkylbenzenesulfonates with 5 to 15 carbon atoms in the alkyl radical and alpha-sulfonated fatty acid methyl esters whose fatty acid content has 6 to 18 carbon atoms. For the purposes of the invention, preference is given to alkyl sulfates having 6 to 18, in particular 8 to 10, carbon atoms in the alkyl radical. In general, it is preferred to use mixtures, in particular mixtures which differ with regard to the C chain lengths of the hydrophobic radical. The alkyl sulfate to be used can be petrochemical in nature and oleochemical in nature. Another important class of surfactants are alkyl ether sulfates with an alkyl chain length of C ₈ to C _18, in particular C ₁₀ to C ₁₆ in the alkyl radical and a chain length of the ether unit derived from ethylene oxide of 1 to 10 ethylene oxide groups per alkyl radical. The anionic surfactants mentioned are present at least in the alkaline range as a salt. 9

Suitable counterions are sodium, potassium, ammonium but also amines such as mono-, di- or triethanolamine.

Another class of surfactants suitable here are sarcosinates. These are, for example, the amides of amino acids with fatty acids, a C chain length of 8 to 18, in particular 10 to 14, to be used in the fatty acid portion. Another class of suitable anionic surfactants are alkyl ester sulfate, which can be prepared by reacting fatty acid esters, in particular fatty acid methyl esters, with SO ₃ . The alkyl ester sulfates mentioned can be present as such or in the form of the disalts of the alpha sulfo fatty acids.

Nonionic surfactants can also be used in the cleaning agents according to the invention. An important class of nonionic surfactants are the reaction products of long-chain alkyl alcohols with 6 to 22 carbon atoms in the alkyl radical with ethylene oxide, propylene oxide or both. Preference is given to substances which are derived from alkyl alcohols of natural origin (fatty alcohols) and have a degree of ethoxylation of 3 to 100, in particular 3 to 20. For some problem solutions, it may be desirable to use non-ionic surfactants which are both ethoxylated and propoxylated and have a degree of ethoxylation of 5 to 30 and a degree of propoxylation of 1 to 10. However, the long-chain alcohols to be used for the class of nonionic surfactants can also be of synthetic origin, for example those such as are obtainable from Ziegler olefin oligomerization or from oxo synthesis. Ethoxylates of C ₁₂ to C ₁₅ alcohols of petrochemical origin or of coconut alcohol or palm kernel oil alcohol are preferred. Another class of nonionic surfactants are the mono- and diethanolamides. Products with 8 to 12 carbon atoms in the fatty acid residue are preferred here. Other suitable nonionic surfactants are the alkyl polyglucosides 3 This acetals from long-chain alcohols, in particular alcohols with 8 to 18 carbon atoms and sugar, where these sugar residues can be monomeric or oligomeric bound to one another via an acetal bond. Alkyl polyglycosides with a C chain length in the alkyl radical of 8 to 12 and a degree of oligomerization of 1.3 to 2.5, in particular 1.4 to 1.7, are preferred. Other suitable nonionic surfactants are the fatty acid glucamides. These are amides from fatty acids with 8 to 22 carbon atoms and N-alkylamino sugars. Preferred among these are fatty acid methylglucamides having 6 to 14 carbon atoms in the fatty acid residue. When formulating the treatment solution according to the invention, the person skilled in the art will ensure that the combination of anionic surfactants, with certain nonionic surfactants such as fatty acid alkanolamides, alkyl glucosides or alkyl glucamides, provides foaming preparations such as that for some applications, for example manual dishwashing is.

Another class of surfactants are semi-polar surfactants. Among them, for example, trialkylamine oxides with a long chain residue are preferred. In particular, substances with an alkyl radical with 6 to 20 C atoms and 2 short-chain radicals with 1 to 4 C atoms, which can also carry a hydroxyl group, can be used here.

In addition to or instead of the anionic or nonionic surfactants mentioned, cationic surfactants can also be used. Among the cationic surfactants, for example, quaternary ammonium salts having a long-chain alkyl radical having 6 to 20, in particular 8 to 16, carbon atoms and 3 short-chain radicals having 1 to 3 carbon atoms, which can also be substituted by a hydroxyl group, are preferred. lo

As far as the formulation in cleaning agents makes it easier, hydrotropes can still be used. These are organic substances that impart the solubility of other substances in water. Substances such as cumene sulfate, but also solvents such as ethanol, isopropanol, ethylene glycol, ethylene glycol and the like are mentioned here.

If the product according to the invention is intended to be a cleaning agent with an abrasive effect, abrasive substances can also be used. Suitable abrasives can be soluble or non-soluble in nature. Among the insoluble ones, mica and certain silicates are preferred among the soluble ones, for example sodium bicarbonate, potassium sulfate or similar salts. Other salts which can be present as adjusting agents in the cleaners according to the invention are sodium sulfate or magnesium salt which have the advantageous effect on the cleaning performance to have.

The cleaning agents according to the invention can also contain additives as are customary below for machine dishwashing detergents which are particularly preferred in the sense of the invention.

A particularly preferred object of the invention are cleaning agents in solid form, in particular for automatic dishwashing. These cleaning agents necessarily contain 2 to 30% by weight of enzyme and enzyme substrate, and in the case of the urease / urea system 0.5 to 25% by weight. Urea can be combined with 1.5 to 5% by weight urease. The cleaning agents according to the invention for machine dishwashing further contain 1 to 50% by weight of a builder component. The person skilled in the art will select a builder component here which is not inherently strongly alkaline. For example, organic polycarboxylic acids and their salts are particularly suitable here. in particular the combinations described above as buffers or enzyme substrates. Thus, according to a preferred embodiment of the invention, the citric acid / alkali citrate system can be used, which is adjusted in particular in such a way that the desired starting pH value between 4 and just under 7 is reached. The cleaning agents according to the invention then further contain at least 100% by weight of at least one active ingredient selected from the group consisting of oxygen bleaches, bleach activators, builders, surfactants and special active ingredients.

In addition to the above-mentioned preferred system of citric acid and citrate, soluble builders are used as builders in the cleaning agents according to the invention for machine dishwashing, which builders can be present as monomeric polycarbonate or polymeric carboxylates. In addition, alkali phosphates, borates and silicates can also be present in small amounts if these are sufficiently stable under the initial pH conditions.

Polymeric carboxylates are understood here to mean copolymers of polymerizable mono- or dicarboxylic acids and their salts. Such polymers are usually produced from acrylic acid, methacrylic acid, itaconic acid, citraconic acid or crotonic acid, from maleic acid or fumaric acid and the anhydride of maleic acid. The polymers mentioned may also contain further monomers, for example acrylamide, but also vinyl acetate, which is hydrolyzed in particular in a further processing step to give polyvinyl alcohol. Suitable polymeric carboxylic acids have a molecular weight between 2000 and 70,000, on the one hand products with a molecular weight in the range from 2000 to 5000 are preferred on the other hand those with a molecular weight range from 20,000 to 70,000. Monomeric polycarboxylates are understood here to mean mono- or polycarboxylic acids with generally no more than 10 carbon atoms and one to six carboxyl groups. The monomeric polycarboxylates described below can be used as acids or as their alkali or ammonium salts, in particular sodium salts, according to the desired pH. The mixtures of the acids and the salts are preferred. Suitable monomeric polycarboxylates with an acid group are lactic acid and glycolic acid. Among the substances with two acid groups, succinic acid, malonic acid, ethylene dioxide acetic acid, maleic acid, fumaric acid, tartaric acid, tartronic acid should be mentioned. Among the monomeric polycarboxylates with three acid groups, in addition to citric acid, aconitic acid, citraconic acid and derivatives of succinic acid such as carboxymethyloxisuccinate, lac- toxysuccinate or 2-oxa 1, 1,3-propanetrycarboxylate should also be mentioned. Among the monomers polycarboxylates with four carboxyl groups, the oxidisuccinates, the 1, 1, 2,2-ethane tetracarboxylates, the 1,1, 3,3-propane tetracarboxylates and the 1, 1, 2,3-propane tetracarboxylates are to be mentioned. In addition to the above-mentioned, carbocyclic or heterocyclic polycarboxylic acids can also be used, for example cyclopropantetracarboxylic acid, cyclopentadiene pentacarboxylic acid, tetrahydrofuran tetracarboxylic acid and their homologues. Aromatic polycarboxylic acids, melitic acid, pyromelitic acid, phthalic acid and their isomers can be used.

Preparations according to the invention for machine dishwashing can furthermore contain a bleaching system. Oxygen bleaching agents are suitable here. In particular, hydrogen peroxide inclusion compounds are used. The sodium salts are usually used, and these in amounts of 1 to 40, in particular 5 to 20,% by weight of the total preparation. Examples of inorganic peroxide salts are the perborates, percarbonates, Perphosphates, persulfates and persilicates. The salts mentioned can be present as such in the preparation. In terms of storage stability, however, it is usually preferred to apply it in an encased form. A preferred embodiment of the invention uses perborates, in particular sodium perborate monohydrate or tetrahydrate. Also preferred is the use of sodium percarbonate, a salt that contains three molecules of hydrogen peroxide per two molecules of sodium carbonate. Percarbonate is generally used in a coated form. Other salts are often used as coating agents here, for example borates but also soaps and the like. Another important salt is the potassium peroxomonopersulfate or the potassium or ammonium peroxidisulfate. In addition to or instead of the compounds mentioned, it is also possible to use organic peracids, for example diperoxidodecanedioic acid, diperoxitetradecanoic acid, diperoxyhexadecanedioic acid and their homologs. These peracids are usually also used as salts, for example as alkali or magnesium salts.

The preparations according to the invention can furthermore contain bleach activators. A preferred group of bleach activators are substances which react with the H ₂ O ₂ present in aqueous liquor after the persalts have been dissolved to give peracids. Substances with N or O acyl groups are suitable here. Reference is made to the teaching of international application WO 95/12652, page 8, which contains a detailed compilation of suitable bleach activators of this type. N, N, N-, N-, tetraacetylethylenediamine, the N-acylamides from Carprolacta or Valerolacta and their substitution products are particularly suitable here. However, O-acyl compounds such as monobenzyl tetraacetyl glucose and anhydrides such as phthalic anhydride are also suitable. Cationic peracid precursors are also suitable IH as described for example in the international patent application cited above.

The detergents according to the invention for machine dishwashing can also contain surfactants in amounts of 0.5 to 10% by weight. Suitable surfactants are listed in the previous chapter. Anionic surfactants and low-foaming nonionic surfactants are preferred for the purposes of machine dishwashing. A particularly suitable class of low-foaming surfactants are the end group-capped ethoxylated fatty alcohols. These are compounds with a long-chain alkyl group of 8 to 18 carbon atoms, a hydrophilic chain derived from ethylene oxide and a closing group of 1 to 4 carbon atoms, the long-chain alkyl group also being able to have a hydroxyl group in two positions.

For the purpose of machine dishwashing, it is preferred to work with a low level of surfactant or under low-foam working conditions. The expert will therefore, if he uses foaming surfactants, at the same time provide foam inhibitors.

The preparations according to the invention for machine dishwashing can furthermore contain special active ingredients, for. B. enzymes, fragrances, dyes, foam inhibitors, stabilizers, silver preservatives, corrosion protection agents and the like.

Manganese (II) salts, for example, are to be mentioned as special active substances, these serve to prevent the black coloring of silver and are generally used in an amount of 0.01 to 4% by weight, in particular up to 1% by weight and preferably 0.02 up to 0.4 wt .-% used. Suitable man- Goan compounds are inorganic salts which can also be present as a hydrate. Manganese sulfate, manganese carbonate, manganese phosphate, manganese nitrate, manganese acetate or manganese chloride should be mentioned. Salts of manganese complexes, in particular salts of chelate complexes with more than one electron donor atom in the molecule, can also be used.

Complexing agents for heavy metals can also be contained in the preparations according to the invention as further special active ingredients. Suitable complexing agents are derivatives of iminoacetic acid such as 2-hydroxyethyliminodiacetic acid or gluceryliminodiacetic acid, but also ethylenediaminetetraacetic acid and the like. Organic diphosphonic acids are also suitable here.

The preparations according to the invention can contain lime soap dispersants as further special active ingredients. It is preferred to choose surfactants that have the appropriate lime soap dispersing effect; suitable here are C ₁₆ to C ₁₈ dimethylamine oxides C ₁₂ to C ₁₈ alkyl ethoxysulfates with an average degree of ethoxylation of 1 to 5 as well as ethoxylated fatty alcohols with a degree of ethoxylation around 12 or around 30.

The preparations according to the invention can furthermore contain foam inhibitors. These are usually used in an amount of 0.1 to 5% by weight. In principle, all known foam inhibitors can be used here, for example foam inhibitors based on silicone or based on 2-alkylalkanol or paraffin foam inhibitors. Copolymers of ethylene oxide and propylene oxide, for example ethoxylated-propoxylated fatty alcohols with an alkyl chain length of 10 to 16 carbon atoms, can also be used here. Atoms and a degree of ethoxylation of 3 to 30 and a degree of propoxylation of 1 to 10.

Other enzymes may also be present in the preparations according to the invention. Suitable other enzymes are amylases, lipases and, if appropriate, also cellulases, glutanases and optionally esterases or proteases. Among the above, proteases are less preferred because they sometimes attack other enzymes. Among the amylases to be used according to the invention, alpha amylases are preferably, for example, alpha amylases from B. Lichiniformis which can be used in an amount of 0.01 to 2% by weight. Lipases from Pseudomonas pseudoalkaligenes or lipases from homiculananigunosa, for example, can be used as lipiases. A suitable enzyme of this type is marketed by Novo Nordisk under the brand name Lipolase. Proteases can be used in amounts of 0.005% by weight to 2% by weight of active enzyme. Serine proteases, in particular serine proteases of the subtilisin type, are suitable here. Proteases from Bacilus lentus, from Bacillus lichiniformis (subtilisin Carlsberg) or Subtilisin BPN. Suitable products are known to the person skilled in the art of detergents and cleaning agents and are commercially available, for example, under the trade names Alkalase or Maxatase.

The automatic dishwashing detergents according to the invention can furthermore contain substances for preventing glass corrosion. Inorganic zinc compounds which are used as water-soluble zinc salts or insoluble as zinc oxide or zinc hydroxide are suitable here, for example. The preparations according to the invention can furthermore contain fluorides, for preventing 1? Change of brown decor discoloration through the aforementioned manganese compounds but also to remove silicate deposits on glasses.

The preparations according to the invention can furthermore contain an organic redox system to prevent the discoloration of silver. Organic, mostly heterocyclic compounds which can also contain nitrogen and sulfur are suitable here. A particularly preferred compound are benzotriazole and isocyanuric acid. Other suitable compounds are the amino acids system and cystine.

19

Examples:

Example 1: Urea urease on a laboratory scale

The submitted pH increases due to the enzymatic release of ammonia from the urea used. The enzyme-catalyzed pH shift is described in the laboratory system described below:

30 ml batches are prepared in each case: A crystallizing dish (d = 110 mm, h = 65 mm) used as a water bath is tempered on a heating stirrer using a contact thermometer.

30 ml of substrate solution are placed in a 50 ml beaker, tempered and adjusted to the required pH. The reaction is started by adding the respective enzyme. The pH value is recorded via a pH electrode which is connected to a recorder (paper feed 2mm / min, sensitivity 100X10 = 20mm / pH level) and can thus be monitored continuously.

Urea - urease

All measurements with urea as substrate are made in 20 mM citric acid buffer / NaOH.

13

Start pH

Starting from pH = 6.0, the enzyme reaction slows down significantly with falling pH start values. When pH <4_ is started, enzyme activity can no longer be measured.

Temperature ° C

A significantly increasing enzyme activity can be achieved by increasing the temperature up to 50 ° C. At 60 ° C there is approximately the same activity as at 50 ° C.

mM urea

With low urea concentrations (e.g. 10mM) only a lower final pH value (pH 6) can be achieved than with higher urea concentrations (20 mM -pH 7.8). 2 (7

mg urease / 30 ml batch

The more enzyme (1-5 mg) is used, the faster the urea is converted, i.e. the desired pH shift takes place.

Example 2: Urea urease in the dishwasher

Dosage for test batches in the dishwasher:

The required amounts of urea and urease are calculated for 51. Approach V 15 g urea

833 mg urease batch VIII 6 g urea

167 urease

The example of a 50 mM urea (3 g / l) and 0.8 g urease (0.16 g / l) (Sigma Chemicals no. U-1500) was used to test the pH shift in a commercially available dishwasher. The starting pH of 4.5 was set with a 20 mM citric acid. The enzymes were added at about 25 ° C. after the pre-rinse was complete. The dishwasher was a Miele G 590. The program was set to 65 ° C universal program. With normal loading, the program reached the target temperature of 64 ° C. within 15 minutes and held the temperature for a further 8 minutes until the end of the cleaning cycle. The pH rose from 4.5 within 5 min (35 ° C) to 5.5, after 10 min (50 ° C) to 7.5 and remained at pH 8.6 after 15 min until the end of the cleaning cycle. While a cleaning cycle with water had little effect on porcelain cups for teenage soiling (grade 1-2 on a scale of 0-10), a grade of 9 was achieved (very good cleaning). This means that a good cleaning of tea Soiling is possible and an alkalinity is present over a long period of time during cleaning, which ensures good action of surfactants and enzymes such as proteases and amylases.

Example 3: Oxaloacetic acid or oxaloacetate - oxaloacetate decarboxylase on a laboratory scale

The enzymatic decarboxylation of the oxaloacetate increases the present pH because a carboxyl group is broken down. The reaction products are pyruvate and carbon dioxide, which for the most part escapes, the proportions of dissolved kohnensäure do not have a great influence on the pH. The decarboxylation of the unstable oxaloacetate described here also takes place spontaneously, especially at higher temperatures.

30 ml of substrate solution are placed in a 50 ml beaker, tempered and adjusted to the required pH. The reaction is started by adding the respective enzyme. The pH value is recorded via a pH electrode which is connected to a chart recorder (paper feed 2mm / min, sensitivity 100x10 = 20mm / pH level) and can thus be monitored continuously.

Oxaloacetic acid or oxaloacetate - oxaloacetate decarboxylase

All measurements with oxaloacetic acid are prepared in water (= oxaloacetate / OAA) and adjusted to pH = 5.0 with NaOH, which means that the starting pH in these experiments is always pH = 5.0. 21

temperature

The spontaneous decomposition of oxaloacetate (and thus the pH shift) is significantly increased by increasing the temperature up to 60 ° C. An additional decarboxylation due to the use of enzymes is therefore only evident at lower temperatures.

mM OAA / oxaloacetate The standard concentration of 10 mM is used. Doubling or halving the substrate concentration shows no great effects.

Units OAA-DC / oxaloacetate decarboxylase

The units specified by the manufacturer are used here as the unit of measurement.

(1 unit converts 1 umol oxalate per min into pyruvate and CO ₂ at pH = 8 and 25 ° C)

pH after 20/40 min

Since the course of the reaction is not linear (see also the course of the pH

Shifts), the pH reached in each case is indicated after 20 or 40 min.

Dosage for test batches in the dishwasher:

The required quantities are calculated for 51.

Batch VI 6.6 g oxaloacetic acid approx. 80 ml 1 N NaOH to adjust the pH

Mixture IX 6.6 g oxaloacetic acid approx. 80 ml 1 N NaOH to remove the pH

0.40 g BLAP 140, resp. 0.80 g Savinase 4.0T

Example 4: Oxalic acid or oxalate - oxalate decarboxylase on a laboratory scale 2 *

The principle is similar to that mentioned above, the reaction products are formate and carbon dioxide. This reaction does not proceed spontaneously, the oxalate is a significantly more stable compound than the oxaloacetate.

30 ml batches are prepared in each case: A crystallizing dish used as a water bath (d = 110 mm, h = 65 mm) is tempered on a heating stirrer using a contact thermometer.

Oxalic acid or oxalate - oxalate decarboxylase

All measurements with oxalic acid are prepared in water (= oxalate) and adjusted to pH = 5.0 with NaOH, that is to say the starting pH in these experiments is always pH = 5.0.

temperature

The enzyme shows no activity at 65 ° C. Units of oxalate decarboxylase

The units specified by the manufacturer (Sigma Chemicals) are also used here as the unit of measurement. (1 unit converts 1 µmol oxalate per min in formate and Co ₂ at pH = 5 and 37 ° C)

Dosage for test batches in the dishwasher:

The required quantities are calculated for 51.

Batch II 0.23 g oxalic acid, 1n NaOH to adjust the pH, depending on the temp. +/- 133 units oxaloacetate decarboxylase.

Example 5: pH shift and generation of hydrogen peroxide by oxalate / oxalate oxidase

30 ml batches are prepared in each case; A crystallizing dish used as a water bath (d = 110mm, h = 65mm) is tempered on a heating stirrer using a contact thermometer.

The concentration of hydrogen peroxide generated is determined by photometric determinations. A hydrogen donor (4-aminophenanzone and chromotropic acid) produces a blue dye in the presence of peroxidase and hydrogen peroxide, the absorption maximum of which is 600 nm. Preparation of the peroxide reagent: 75 mM KH2PO4 125 mM NaH2PO4 x H2O 10 mM chromotropic acid 0.5 mM 4-aminophenanzone

in 250 ml bidist. water

The test approach includes:

2.4 ml of peroxide reagent

0.1 ml horseradish peroxidase (2U / ml)

0.1 ml sample solution with hydrogen peroxide

The detection reaction is started by adding the hydrogen peroxide. The measurement is carried out at 600 nm. The evaluation is carried out against a calibration curve. The standard solutions for this were determined potentiometrically.

Oxalic acid or oxalate - oxalate oxidase

All measurements with oxalic acid are prepared in water (= oxalate) and adjusted to pH = 4.0 with NaOH, that is to say the starting pH in these experiments is always pH = 4.0. It starts after saturation with oxygen by adding the enzyme 21

Units of oxalate decarboxylase

Oxalate oxidase Sigma Chemicals No. O-4127

The units specified by the manufacturer (Sigma Chemicals) are as

Unit of measure used. (1 unit forms 1 µmol of hydrogen peroxide per minute

Oxalate at pH = 3.8 and 37 ° C).

Claims

Patent claims:

1. A process for the automatic shift of the pH of an aqueous treatment solution from acid to alkaline, characterized in that the desired acidic starting pH is set in an aqueous liquor, simultaneously or subsequently an ammonia-generating and / or an organic The carboxylic acid-consuming enzyme and its substrate are added, whereupon the enzymatic reaction is allowed to proceed until the desired final pH is reached.

2. The method according to claim 1, characterized in that urease is used as the enzyme and urea as the substrate.

3. The method according to claim 1, characterized in that a decarboxylase is used as the enzyme and a carbon- in particular a dicarboxylic acid is present as the substrate.

4. The method according to claim 1 and 3, characterized in that an oxaloacetate decarboxylase is used as the enzyme and oxaloacetic acid or its salts are used as the substrate.

5. The method according to claim 1 and 3, characterized in that oxalate decarboxyiase are used as the enzyme and oxalic acid is used as the substrate. 21

6. The method according to claim 1, characterized in that oxalic acid are used as the enzyme oxidase and substrate.

7. The method according to claims 1 to 6, characterized in that it is carried out at temperatures between 10 and 70 ° C.

8. The method according to claims 1 to 7, characterized in that the acidic pH is used with the aid of a buffer solution, in particular with a buffer solution of an organic polyfunctional carboxylic acid and its alkali metal or ammonium salt.

9. The method according to claims 1 to 8, characterized in that the treatment solution is constructed as a cleaning solution or as a coloring solution.

10.The method according to claims 1 to 9, characterized in that the treatment solution further contains one or more additives from the group of surfactants, detergent builders, bleaches, Bieich activators, enzymes such as proteases, lipases, amylases, foam inhibitors.

10. Detergent in solid form, in particular for machine dishwashing, containing 2 to 30% by weight of enzyme and enzyme substrate

1 to 50% by weight of a mixture of an organic polycarboxylic acid and its salt and from 100% by weight of at least one active ingredient selected from the group consisting of oxygen bleaches, bleach activator builders, surfactants and special active ingredients. 20th

11. Cleaning agent according to claims 1 to 10, characterized in that parborate tetrahydrate, perborate monahydrate and / or percarbonate are used as the oxygen bleaching agent.

12. Cleaning agent according to claims 1 to 11, characterized in that the bleach activators used are N-acyl and / or O-acyl compounds, preferably N, N'-acylated diamines such as tetraacetylethylene diamine or acylcaprolactam.

13. Cleaning agent according to claims 1 and 12, characterized gekennzeich¬ net that alkali polyphosphates in particular sodium or potassium tripolyphosphate, alkali silicate of disilicate type or insoluble builders such as zeolite A are used as builders.

14. Cleaning agent according to claims 1 to 13, characterized in that anionic surfactants, nonionic surfactants or cationic surfactants are used as surfactants, weakly foaming nonionic surfactants being used in detergents for machine dishwashing and mixtures of anionic surfactants, highly foaming for manual dishwashing, not ¬ ionic surfactants and amphoteric surfactants are preferred.

15. Cleaning agent according to claims 1 to 14, characterized in that enzymes, fragrances, dyes, foam inhibitors, stabilizers, silver protection agents, corrosion protection agents and the like are used as special active ingredients.