EP0191372A1 - Active agent concentrates for alkaline cleaner having two constituents, method for their fabrication and their use - Google Patents

Abstract

The invention relates to active ingredient concentrates B for alkaline cleaners consisting of two components A and B, one component A of which is a strongly alkaline, predominantly alkali metal hydroxide-containing and used in excess basic solution, and the other component B of which is silica and, as further additives, anionic, nonionic or amphoteric surfactants, builder substances, stabilizers and optionally inorganic mineral acids, complexing agents and / or preservatives containing aqueous dispersion, which are characterized in that they as a set at a pH in the range from 1 to 11 active ingredient by treatment of alkali metal silicate solutions with mineral acids or In aqueous solution, gases reacting acidic in situ and containing silica and tensides and stabilizers as well as, if necessary, mixed with other builder substances, optionally together with other agents common in cleaner concentrates, contains old, a process for the preparation of such active substance concentrates, by treating alkali metal silicate solutions with mineral acids or gases reacting acidic in aqueous solution and adding acidic dispersions thus obtained with surfactants and stabilizers, and optionally with other builder substances and other agents customary in cleaner concentrates, and the use thereof active ingredient concentrates of this type in alkaline two-component cleaners for cleaning rigid materials.

Description

The invention relates to active ingredient concentrates for alkaline two-component cleaners, processes for their preparation and their use.

To clean rigid materials, for example workpieces made of metal or glass, alkaline cleaning agents are used, which contain caustic soda, orthophosphates, condensed phosphates, silicates, complexing agents, wetting agents and optionally corrosion inhibitors, anti-foaming agents and preservatives. In general, products containing these constituents are marketed as powdery mixtures and are fed discontinuously to the cleaning bath in powder form, the concentration of the cleaning agent in the bath depending on the application and degree of soiling being between 0.1 and 20% by weight.

The prerequisite for the effectiveness of the cleaning solution is compliance with the optimal concentration of the cleaning agent components. This can be determined by titration or a conductivity measurement. The conductivity measurement for determining the concentration can be carried out in conjunction with an automatic metering of the powder mixture in order to set the desired detergent concentration.

A disadvantage of working with powdered products, especially if they contain hygroscopic salts, is that it is difficult to ensure continuous, trouble-free metering. Furthermore, particularly effective nonionic surfactants are sensitive to solid caustic soda. If stored for a long time, they will be oxidized to ether carboxylic acids. This results in a deterioration in the effectiveness of certain cleaning processes and in a spray application of the cleaning solution causes an annoying foam formation.

In addition to powder detergents, the use of liquid alkaline detergent concentrates is also known. According to DE-OS 14 67 605, losses of polymer phosphates occurring during prolonged storage of these concentrates can be compensated for by hydrolysis and the poor compatibility of the nonionic wetting and antifoam agents and polymer phosphates contained therein with the remaining detergent concentrate in that the detergents are treated with a liquid, acidic, non-ionic wetting agents and / or anti-foaming agents and water-soluble organic compounds which form complexes with the hardness formers of the water Acids or their active ingredient concentrate containing acid salts added. These acidic or neutral reacting active substance concentrates were then processed into alkaline liquid cleaners by adding an excess of alkali. However, the disadvantage of such an approach is that silicate-containing cleaning agents in this way could not be made because the surfactants used with high concentrations Builder, that large amounts of Sili _- cates in the solution are not compatible.

According to DE-OS 32 46 080, cleaning concentrates have now been produced from two components, one of which essentially consists of sodium hydroxide solution and the second contains the other constituents of the cleaner. The latter solution can be adjusted to acidic or neutral pH values, an acidic setting having the advantage that all of its components, in particular the surfactants, are particularly readily soluble. The disclosed two-component cleaners are characterized in particular by the fact that the acidic or neutral component is an aqueous dispersion of silica which has been prepared from pyrogenic or precipitated silica and optionally contains further constituents, such as phosphoric acid, sulfuric acid, polyphosphates, surfactants, stabilizers and / or preservatives can.

A silica obtained from water glass by precipitation with sulfuric acid, washing out and drying was used for the preparation of the silica dispersions. However, the process of precipitating silica by acid treatment in water glass and washing and drying the precipitate is very complex and difficult to carry out, especially on an industrial scale. In addition, the silica obtained in this way is relatively poorly soluble when used in two-component cleaners. Solubility disadvantages arise in particular when the Si02 / Na20 ratio in the cleaning bath is greater than 0.3: 1. Another disadvantage of using precipitated and isolated silica is the fact that, due to the limited solubility of nonionic surfactants, relatively acidic concentrates have to be prepared in order to ensure adequate stabilization. The consequence of this is that large amounts of alkali metal hydroxide have to be added to neutralize or to set a preferably alkaline pH of cleaning solutions.

It has now been found that it is in no way necessary to isolate and dry silica precipitated from water glass with the aid of acids. Rather, highly effective liquid two-component cleaning systems with silica dispersions could be obtained, which were obtained in situ by precipitating the silica from soda or potassium water glass with acids and mixed with stabilizers, surfactants and possibly other builder substances. It is surprising that salts formed during neutralization do not impair the stability of the suspensions. In addition, it is possible to produce stable and storable active ingredient concentrates with pH values in the alkaline range (up to pH 11).

The invention therefore relates to active ingredient concentrates B for alkaline cleaners consisting of two components A and B, one component A of which contains a strongly alkaline, predominantly alkali metal hydroxide and in excess used basic aqueous solution and its other component B is a silica and, as further additives, anionic, nonionic or amphoteric surfactants, builder substances, stabilizers and optionally inorganic mineral acids, complexing agents and / or preservatives containing aqueous dispersion, which are characterized in that they as an active ingredient component adjusted to a pH in the range from 1 to 11, a silica dispersion obtained in situ by treating alkali metal silicate solutions with mineral acids or in aqueous solution and reacted with surfactants and stabilizers and optionally with other builder substances, if appropriate in addition to other, conventional in cleaner concentrates Funds included.

The invention also relates to a process for the preparation of active ingredient concentrates B for alkaline cleaners consisting of two components A and B, one component A of which is a strongly alkaline, predominantly alkali metal hydroxide-containing and used in excess, and the other component B of which is a silica and, as another Additives are anionic, nonionic or amphoteric surfactants, builder substances, stabilizers and optionally inorganic mineral acids, complexing agents and / or preservatives containing aqueous dispersion, which is characterized in that alkali metal silicate solutions are treated with mineral acids or in aqueous solution gases reacting and the resulting silica dispersions with Surfactants and stabilizers and, if appropriate, mixed with other builder substances and other agents customary in cleaner concentrates.

The invention also relates to the use of such active substance concentrates B in alkaline two-component cleaners for cleaning rigid materials.

Suitable for the purposes of the invention are aqueous alkali metal silicate solutions whose Si0 ₂ - / M ₂ 0 ratio (M = alkali metal) is in the range from 2 to 3.5. In principle, soda and potash water glass solutions are equally well suited. However, aqueous sodium silicate solutions are preferably used, since they are cheaper and accessible in larger quantities.

In a preferred embodiment of the invention, undiluted technical water glass solutions are used. This has proven to be advantageous if only because a high active substance content is sought for the active substance concentrates which, when dilute solutions are used, further process steps to increase the active substance content, e.g. Concentration of the dispersion by evaporation or filtration required. These steps become unnecessary if concentrated solutions are used.

The silica precipitated in situ is prepared by reacting the water glass solutions mentioned with any mineral acids or gases which react with an acid in an aqueous solution, for example HC1, SO ₂ and / or CO ₂ . When using acidic gases, precipitation with CO _{2 is} preferred. When using mineral acids, phosphoric acid and sulfuric acid as well as a mixture of both acids in a weight ratio of 3: 1 to 1: 3 have proven their worth. A ratio of 1: 1 is particularly preferred. In practice, concentrated ones are advantageously used Acids are used to achieve a high active ingredient content in the resulting silica dispersions.

During the precipitation reaction, the pH should be between 8 and 10 and the reaction temperature between 60 and 90 ° C. Under these conditions, silica grades are obtained which provide particularly stable dispersions. The specified range of pH can advantageously be maintained when working in a buffer system. Alkali metal salts of acids whose anions have a buffering action in the pH range from 8 to 10, for example phosphates, carbonates and / or borates, are particularly suitable as buffers. The buffering salts can be placed in aqueous solution for the precipitation reaction or can form in the course of the precipitation reaction.

When the silica is precipitated from the alkali metal silicate solutions with sulfuric acid, it has proven to be advantageous to present the desired amount of phosphate in the active ingredient concentrate as an aqueous solution and to effect a silica precipitation by simultaneously metering in water glass solution and sulfuric acid.

At the end of the precipitation, the dispersion can be adjusted to the desired pH in the acidic, neutral or alkaline range. With an excess of mineral acid, pH values around 1 can be achieved without this impairing the suitability of the dispersions for alkaline two-component cleaners. However, the dispersions are preferably adjusted alkaline to pH values from 8 to 11, for which purpose aqueous sodium hydroxide solution or potassium hydroxide solution, sodium orthophosphate or Potassium orthophosphate, sodium carbonate or potassium carbonate and / or sodium silicates or potassium silicates can be used.

For the intended use of the active compound concentrates according to the invention in alkaline two-component cleaners, a certain content of builder salts which are formed during in-situ precipitation or are added as a buffer is advantageous. Builder salts are understood to mean salts which enhance the cleaning action of the surfactants, for example alkali metal orthophosphates and / or polyphosphates, carbonates, borates and / or sulfates. In particular, alkali metal polyphosphates, i.e. Alkali metal pyrophosphate and / or tripolyphosphate.

In order to achieve a good cleaning effect, it is also expedient to add surfactants to the silica dispersion. Anionic, nonionic and / or amphoteric surfactants are suitable for this purpose. Compounds such as alkylbenzenesulfonates, alkylsulfonates, fatty alcohol sulfates, adducts of ethylene oxide and / or propylene oxide with fatty alcohols, fatty amines and alkylphenols and surface-active ethylene oxide / propylene oxide block polymers are particularly suitable. The chain lengths of the alkyl radicals are in the range from 8 to 20 C atoms for the compounds mentioned and in the case of the alkylphenols in the range from 6 to 18 C atoms. Also suitable as amphoteric surfactants are compounds such as alkyldimethylammonium betaines having 12 to 18 carbon atoms in the alkyl radical.

In a preferred embodiment of the present invention, the precipitation of the silicas from Al Kalimetallsilikatlösungen by mineral acids also in the presence of the surfactants mentioned. This procedure in particular facilitates the stabilization of alkaline dispersions containing nonionic surfactants.

In addition, the silica dispersions for the active compound concentrates according to the invention can also contain complexing agents, such as Alkali metal salts of nitrilotriacetic acid, ethylenediaminetetraacetic acid, gluconic acid, citric acid or phosphonic acids (e.g. hydroxyethane-1,1-diphosphonic acid, aminotrimethylenephosphonic acid and 2-phosphono-1,2,4-butane tricarboxylic acid).

Compounds are used as stabilizers which prevent the sedimentation of the silica in the dispersions. For example, pure substances or mixtures from the group of vegetable gum, ie xanthan, and the copolymers of polyalkyl vinyl ethers and carboxylic acid anhydrides are used, for example GANTREZ ^R AN types from GAF Corporation, such as copolymers of polymethyl vinyl ethers and maleic anhydride.

The active ingredient concentrate B contains 10 to 26% by weight, preferably 15 to 25% by weight, particularly preferably 18 to 22% by weight, of silica, calculated as SiO ₂ ; 5 to 27% by weight, preferably 8 to 25% by weight, particularly preferably 13 to 24% by weight, builder; 0.5 to 12% by weight, preferably 1 to 10% by weight, particularly preferably 1 to 8% by weight of surfactants; 0.2 to 5% by weight, preferably 0.3 to 3% by weight, particularly preferably 0.5 to 2% by weight, of stabilizers; and 0.5 to 10% by weight, preferably 1 to 8% by weight, particularly preferably 2 to 7% by weight, of complexing agent.

The alkaline component A for the alkaline two-component cleaners consists essentially of sodium hydroxide solution or potassium hydroxide solution. Further constituents, such compounds may optionally be considered that with the components of erfindungsge _- Maessen silica dispersion component are incompatible, such as lignin. The aqueous alkali metal hydroxide solution is used in excess for two-component cleaners; this is to be understood as an amount of sodium hydroxide solution or potassium hydroxide solution which is sufficient to give the two-component cleaner concentrate a pH greater than 11, preferably greater than 12, after combining the alkaline and the silica dispersion components according to the invention.

To prepare a two-component cleaning solution, the active ingredient components A and B are mixed in water heated to at least 40 ° C., the silica being converted to water-soluble silicates. PH values greater than 12 are reached.

The advantage of using the active substance concentrates B according to the invention which contain precipitated silica is to be seen in the fact that the dispersions are substantially more soluble under the preparation conditions of a detergent bath than dispersions known from the prior art. In addition, the use of the silica precipitated in situ offers greater freedom in the formulation of the active ingredient concentrates with respect to the other components. For example, the use of alkaline salts as a builder is made possible. Compared to systems known from the prior art, it can also be combined of the two components for the cleaning bath, part of the alkali metal alkali can be saved if the active compound concentrates according to the invention have already been adjusted to a pH of 8 to 11 and thus a neutralization of strongly acidic components with large excesses of alkali metal hydroxides is no longer necessary.

Another advantage of the procedure according to the invention can be seen in the fact that the step of washing out the precipitated silica, which is at least technically complex for larger amounts of substance, and the steps of separating from the precipitation solution and drying the isolated silica are unnecessary. In addition, it is to be regarded as advantageous that higher salt contents do not impair the stability of the silica dispersions or the effectiveness of the two-component cleaners that are formed.

The process is explained in more detail by the examples below.

example 1

To 8 l of a 2% disodium hydrogenphosphate solution, 35 kg of sodium water glass, which was adjusted to an SiO ₂ / Na ₂ O weight ratio of 3.3 and a total solids content of 35%, were simultaneously added at 80 ° C. with the aid of two metering pumps, and 4 , 7 kg of a mixture of 98% sulfuric acid and 85% phosphoric acid in a weight ratio of 1: 1 are metered in such that the pH is always kept in the range from 8 to 9. The suspension was 1.0% xanthan as a stabilizer, 2% of an addition product of 14 EO Nonylphenol and 1% alkylbenzenesulfonic acid added. The dispersion had a pH of 8.5. By adding 5 kg of soda water glass, the pH rose to 10.4. The dispersion remained stable.

Example 2

To 8 1 of a 10% sodium triphosphate solution, 40 kg of potassium water glass with an SiO ₂ / K ₂ 0 weight ratio of 2.1 and a total solids content of 40% and 6 kg of 98% sulfuric acid were simultaneously metered in at 70 ° C., so that a pH -Value between 8 and 9 was observed. 1.5% xanthan as a stabilizer, 2% of an addition _product of _{14 EO} with _C12-18 fatty alcohol and 1% alkylbenzenesulfonic acid were also added to the _suspension .

Example 3

60 g of alkylbenzenesulfonic acid and 240 g of nonylphenol + 14 EO were added to 5 l of a 2% disodium hydrogenphosphate solution in a stirred vessel and the mixture was heated to 80.degree. 3.8 kg of a mixture of 98% sulfuric acid and 85% phosphoric acid in a weight ratio of 5: 1 and 40 kg of sodium silicate with an SiO ₂ / Na ₂ O weight ratio of 3.3 and a density of 1 were simultaneously added to this solution. 35 g / cm ³ metered in so that the pH was kept in the range from 8.8 to 9.2. After the reaction was complete, a dispersion with a pH of 9.1 was formed. 0.3% of a stabilizer mixture of xanthan and a copolymer based on polymethyl vinyl ether / tsaleic anhydride (GANTRE _Z ^R AN 149) was added to the dispersion.

Example 4

• In einem Reinigungsbad, das 5 % Natronlauge und 1 % Kieselsäure enthielt, wurde bei 60°C eine vollständige Auflösung der Kieselsäurearten

• a) in situ gefällte Kieselsäure nach 4 min (aus Beispiel 1, 3 Monate gelagert)
• b) Fällungskieselsäure FK 320 nach 7 min (Fa. DEGUSSA)

erreicht.The following example explains the better dissolution behavior of the in situ precipitated silica compared to commercially available precipitated silica:

• A complete dissolution of the types of silica was carried out at 60 ° C. in a cleaning bath which contained 5% sodium hydroxide solution and 1% silica

• a) silica precipitated in situ after 4 min (stored from example 1, 3 months)
• b) Precipitated silica FK 320 after 7 min (DEGUSSA)

reached.

Example 5

The advantage of silica precipitated in situ with regard to the uniform and stable distribution of surfactants in liquid builder-containing active ingredient concentrates compared to solutions without silica becomes clear when comparing solutions and dispersions: As the active ingredient concentrates a, b, c, d in Table 1 show In the presence of surfactants (here eg nonylphenyl + 14 EO) only limited builder concentrations could be selected in order to obtain a solution that was just stable at room temperature. In contrast, in the case of dispersions e and f, surfactants were homogeneously distributable even at high builder concentrations and had a long shelf life.

Active ingredient concentrates:

Example 6

The advantage of the silica precipitated in situ over conventional, commercially available silica produced by acid precipitation with regard to a uniform and stable distribution of surfactants in liquid builder-containing active ingredient concentrates becomes clear by comparing the dispersion (f) of Example 5 with the dispersion formulated below:

This dispersion showed measurable segregation after only two months; The wetting agent separated visibly on the surface of the concentrate.

In comparison, the dispersion (f) of Example 5 was still homogeneous even after a long storage period (12 months) and segregation was not observed.

Example 7

Manufacture and use of two-component cleaners

Greased, deep-drawn steel parts stored for three months were degreased in an alkaline cleaner solution (I) prepared with the active ingredient component (B) according to the invention and, in comparison, with a similar alkaline cleaner solution (II) made from powdery cleaner.

• 25 g/1 Kieselsäuredispersion (siehe unten) und 50 g/1 Natronlauge, 50%ig

Kieselsäuredispersion:

Reinigerlösung II:

• 50 g/1 eines pulverförmigen Reinigers folgender Zusammensetzung:
  

The cleaning solutions were composed as follows: Cleaning solution I:

• 25 g / 1 silica dispersion (see below) and 50 g / 1 sodium hydroxide solution, 50%

Silica dispersion:

Cleaning solution II:

• 50 g / 1 of a powdered cleaner with the following composition:
  

The detergent solutions (I) and (II) prepared with the opposite components showed a cloud point of 62 ° C at 80 ° C at the same active ingredient concentrations (50 g / 1). The degreasing time was 12 minutes with freshly prepared cleaner solution (I) and 13 minutes with freshly prepared cleaner solution (II).

As Table 2 below shows, the storage of the cleaner solution (I) prepared with the active compound concentrate according to the invention had no effect on the degreasing time and cloud point of the cleaner. On the other hand, these properties changed with the solution that was produced with the powdered cleaner over a longer storage period. The nonionic surfactants contained therein were in the presence of caustic alkalis and Atmospheric oxygen is broken down into anionic surfactants. This degradation of the nonionic surfactants was also associated with an increase in the foaming power, which had a disruptive effect, in particular, for sprayable cleaning solutions.

Claims (23)

1. Active substance concentrates B for alkaline cleaners consisting of two components A and B, one component A of which contains a strongly alkaline, predominantly alkali metal hydroxide and used in excess, and aqueous base solution and the other component B of which is silica and, as further additives, anionic, nonionic or amphoteric surfactants , Builder substances, stabilizers and optionally inorganic mineral acids, complexing agents and / or preservatives containing aqueous dispersion, characterized in that it is acidic as a component of the active ingredient adjusted to a pH in the range from 1 to 11 by treating alkali metal silicate solutions with mineral acids or in aqueous solution Reacting gases obtained in situ and with surfactants and stabilizers and, if appropriate, mixed with other builder substances, optionally contain, in addition to other agents customary in cleaner concentrates. 2. Active ingredient concentrates according to claim 1, characterized in that they contain a silica dispersion prepared from sodium silicate or potassium silicate solutions. 3. Active ingredient concentrates according to claim 2, characterized in that they contain a silica dispersion prepared from sodium silicate or potassium silicate solutions with an SiO ₂ - / M ₂ O ratio (M = Na, K) in the range from 2 to 3.5. 4. Active ingredient concentrates according to Claims 1 to 3, characterized in that they contain a silica dispersion precipitated by treatment with sulfuric acid or phosphoric acid or mixtures of sulfuric acid and phosphoric acid in a ratio of 3: 1 to 1: 3. 5. active ingredient concentrates according to claim 4, characterized in that they contain a mixture of sulfuric acid and phosphoric acid in a ratio of 1: 1 precipitated silica dispersions. 6. Active ingredient concentrates according to Claims 1 to 3, characterized in that they contain a silica dispersion precipitated by treatment with HCl, SO ₂ and / or C0 ₂ in aqueous solution. 7. active ingredient concentrates according to claim 6, characterized in that they contain a precipitated silica treatment by treatment with C0 ₂ in aqueous solution. 8. active ingredient concentrates according to claims 1 to 7, characterized in that they contain anionic, nonionic and / or amphoteric surfactants. 9. active ingredient concentrates according to claims 1 to 8, characterized in that they are adjusted to a pH in the range from 8 to 11. 10. active ingredient concentrates according to claims 1 to 9, characterized in that they contain buffering builder salts in the pH range from 8 to 10. 11. Active ingredient concentrates according to claim 10, characterized in that they contain alkali metal orthophosphates, alkali metal polyphosphates, alkali metal carbonates, alkali metal borates and / or alkali metal sulfates, preferably alkali metal polyphosphates. 12. Process for the preparation of active ingredient concentrates B for alkaline cleaners consisting of two components A and B, one component A of which contains a strongly alkaline, predominantly alkali metal hydroxide and is used in excess, and the other component B of which is silica and, as further additives, anionic, A nonionic or amphoteric surfactants, builder substances, stabilizers and optionally inorganic mineral acids, complexing agents and / or preservatives containing aqueous dispersion, characterized in that a) alkali metal silicate solutions at a pH between 8 and 11 treated with mineral acids or gases reacting acidic in aqueous solution and b) the silica dispersions obtained in this way are mixed with surfactants and stabilizers and, if appropriate, with other builder substances and other agents customary in cleaner concentrates. 13. The method according to claim 12, characterized in that one carries out the precipitation of the silicas from the alkali metal silicate solutions in the presence of the surfactants. 14. The method according to claims 12 and 13, characterized in that one as alkali metal silicate solutions Concentrated water glass solutions with a Si0 ₂ - / M ₂ 0 ratio (M = alkali metal) used in the range of 2 to 3.5. 15. The method according to claims 12 to 14, characterized in that concentrated mineral acids are used as mineral acids. 16. The method according to claims 12 to 15, characterized in that one uses sulfuric acid or phosphoric acid or mixtures of sulfuric acid and phosphoric acid in a ratio of 3: 1 to 1: 3. 17. The method according to claim 16, characterized in that one uses a mixture of sulfuric acid and phosphoric acid in a ratio of 1: 1. 18. The method according to claim 17, characterized in that one uses a mixture of 98% sulfuric acid and 85% phosphoric acid in a weight ratio of 1: 1. 19. The method according to claims 12 to 14, characterized in that hydrogen chloride gas, sulfur dioxide gas and / or carbon dioxide gas is used as the gases which react acidically in aqueous solution. 20. The method according to claim 19, characterized in that one uses carbon dioxide gas. 21. The method according to claims 12 to 20, characterized in that the precipitation reaction in the presence of buffering builder substances, such as alkali tallorthophosphates, alkali metal polyphosphates, alkali metal carbonates, alkali metal borates and / or alkali metal sulfates, preferably in the presence of alkali metal polyphosphates. 22. The method according to claims 12 to 21, characterized in that anionic, nonionic and / or amphoteric surfactants are added to the silica dispersions. 23. Use of the active ingredient concentrates according to claims 1 to 11 in alkaline two-component cleaners for cleaning rigid materials, in particular workpieces made of metal or glass.