WO1995002674A1

WO1995002674A1 - Prevention of the formation of filmy deposits after rinsing in non-domestic cleaning processes

Info

Publication number: WO1995002674A1
Application number: PCT/EP1994/002211
Authority: WO
Inventors: Thomas Molz; Gaby Hecht
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1993-07-15
Filing date: 1994-07-06
Publication date: 1995-01-26
Also published as: DE4323638A1

Abstract

The invention concerns a method of preventing filmy deposits forming on glass, plastic, metal or painted surfaces when hard water is used after cleaning to rinse the surface, the method using amino-group-containing polyacrylate copolymers. The invention also concerns an aqueous concentrate for use in the method.

Description

'Prevention of water stains during technical cleaning'

The invention is in the field of technical cleaning, in particular the cleaning of road and rail vehicles as well as machine cleaning etc. in factories. It relates to a process for preventing deposits, spotty drying and veils on glass, plastic, painted or metallic surfaces during rinsing processes with water that has not been completely demineralized, using cationically modified polymers of the polyacrylate type.

If, after acidic, neutral or alkaline cleaning of glass, plastic, painted or metallic surfaces with aqueous cleaning solutions, such as in the cleaning of road or rail vehicles or in machine cleaning etc. in factories, with hardening agents -washed water such as city water, streaks or stains appear when dried-in rinsing water remains, which consist of salt residues from the washing and rinsing water - hereinafter briefly referred to as water stains. These spots give the surface an unsightly appearance.

This problem can be solved by rinsing with demineralized water (= deionized water) at the end of the cleaning. However, the effort for the preparation of demineralized water is relatively high. In addition, the required regeneration of the ion exchanger leads to a salt load in the wastewater and thus to ecological disadvantages. There is therefore interest in products which, when added to tap water which has not been desalinated, permit residue-free drying of rinsing water residues.

Such rinse aid products (rinse aid) are already known in technology, for example in automatic dishwashing. They are based on Solutions of hydroxypolycarboxylic acids containing surfactants such as citric acid or tartaric acid. However, these products primarily have the task of making it possible for the washing water to run off on the slanted dishes by reducing the surface tension. When rinsing water residues dry on horizontal surfaces or in depressions, the formation of water stains cannot be avoided with these products, especially on dark surfaces.

In vehicle washing systems, it is known to add water-repellent substances to the rinse water, for example salts of quaternized alkylammonium ions or fatty acid esters. By hydrophobicizing the lacquer surface, they cause the water film to tear open and the rinsing water to run off more quickly on inclined surfaces and thus accelerate drying. As a result, the risk of water stains on vertical surfaces is reduced, but is not eliminated in particular on horizontal surfaces. While the aim of this treatment is to accelerate the drying by means of brief hydrophobization, a hydrophobizing treatment which is usually known as "waxing in" or "preserving" is also known, which is intended to make the vehicle paint water-repellent in the long term. This is done after the last rinsing step, for example by fogging the vehicle with an aqueous emulsion of a mineral or silicone oil. Such hydrophobizing treatments lie outside the scope of this invention.

In contrast, DE-A-21 61 591 describes a hydrophilizing treatment of surfaces made of glass or ceramic with 0.001 to 40% aqueous solutions of cation-active polyelectrolytes such as polymeric ethyleneimines, polymeric dimethylaminoethyl acrylate or methacrylate or their copolymers with nonionic monomers such as acrylic id, acrylonitrile or their derivatives. An application of such solutions is seen according to the task and examples in the wetting of glass, in particular in windshield washer systems of vehicles. No information is given as to whether a certain pH range is to be observed. The hydrophilization is intended to prevent streaking on the vehicle windows in wet weather and thereby improve visibility. In addition, the applicability as rinse aid at automatic dishwashing. On the other hand, no statements are made about the effects of such solutions on painted surfaces and in particular about their influence on water stains and a corresponding application is not suggested.

A product based on water-soluble salts of lignin sulfonic acid was developed for the final rinse when cleaning road or rail vehicles. For example, DE-A-25 18 391 describes a process for preventing deposits, drying and streaks on glass, painted or metallic surfaces during rinsing operations with hard water, by treating the surfaces with solutions at temperatures between 4 and 40 ° C. which contain one or more salts of lignin sulfonic acid with monovalent cations or magnesium in concentrations of 0.02 to 0.04% by weight per degree of German hardness as well as additional surfactant and have a pH between 4 and 8. Such rinse solutions have a satisfactory effect on surfaces from which the rinse water can drain off completely or can be blown off with air. However, if flushing water remains on horizontal surfaces or in depressions and dries, water stains are observed even in the presence of lignin sulfonate.

The invention is therefore based on the object, following an aqueous cleaning of road and rail vehicles, machines and similar technical devices, a method for preventing deposits, spotty drying and streaks on glass, plastic, painted or metallic surfaces during rinsing processes with hardness ¬ ner-containing water and a rinse water additive for performing the method.

The object is achieved by using a cationically modified polymer of the polyacrylate type as an additive to the rinse water. The invention relates to the

Use of copolymers containing amino groups, obtainable by copolymerizing, based in each case on polymer a), 15 to 90% by weight of one or more nitrogen-free monomers with an olefinic double bond and b) 10 to 85% by weight of one or more linearly polymerizable monomers containing at least one tertiary amino function, diallylamine, 2-vinylpyridine and / or 4-vinylpyridine, the amino groups of the copolymers being neutralized or quaternized with acids until a clear water-soluble preparation has been achieved are, as an additive to rinsing water after the cleaning of glass, plastic, painted or metallic surfaces with aqueous solutions,

as well as a

Process for rinsing after the cleaning of glass, plastic, lacquered or metallic surfaces with water containing hardness, using the copolymers containing amino groups mentioned above.

Suitable copolymers are characterized in more detail in the applicant's DE-A-3839935, which is hereby made part of this disclosure, where their use as a temporary, water-removable coating for painting booths is described. Accordingly, esters of acrylic or methacrylic acid with Cj-C / j-monoalkanols, optionally in a mixture with acrylic and / or methacrylic acid, are particularly suitable as nitrogen-free monomers. Preferred monomers containing amino groups are esters of acrylic or methacrylic acid with C2-Cö monoalkanols and / or diethylamino compounds having a tertiary amine function. The neutralization of the amine functions after the polymerization is preferably carried out using phosphoric acid.

The polymers which can be used according to the invention accordingly contain a minimum proportion of nitrogen-free monomers. In contrast, in the exemplary embodiments of DE-A-21 61 591 mentioned above, polymers are used which only contain monomers containing trialkylammonium groups. Polytrimethylammonium chloride ethyl methacrylate and polytrimethylammonium ethyl ethacrylate are mentioned as examples. In the description of this, it is stated that the cationic monomers can also be copolymerized with nonionic monomers, examples of nonionic monomers being only the nitrogen-containing monomers Acrylamide and acrylonitrile can be specified. The polymers of this laid-open specification are therefore modified much more cationically than those to be used according to the invention.

The salts of divalent cations, particularly Ca (II) and Mg (II), which usually occur in city water, are referred to as hardness formers. These salts can be present as bicarbonates, for which the term "temporary hardness" or "carbonate hardness" is common, or they are present as "permanent hardness", for example in the form of carbonates, sulfates or chlorides. In industry, the hardness-forming agent content is often given in German degrees of hardness (° d), with 1 ° d having an alkaline earth ion concentration of 0.18 mmol / 1 or a calculated content of CaCO3 of 17.8 ppm (= ° US) corresponds.

The addition according to the invention to rinse water containing hardness-forming agents is suitable for degrees of hardness up to 30 ° d and is particularly effective for the German "hardness ranges 2 and 3", i.e. for 7 to 21 ° d or 1.2 to 3.8 iranol alkaline earth ions per 1. It is immaterial whether the hardness is carbonate or permanent.

The effective concentration range of the additive according to the invention depends on the degree of hardness of the water used. For the hardness range up to 21 ° d, polymer concentrations in the rinse water between 0.2 and 0.4% by weight are suitable, for degrees of hardness up to 30 ° d the polymer concentration can be increased to 0.4 to 0.8% by weight. Polymer concentrations above 1% by weight are less preferred since the thicker polymer films caused thereby can be visually disruptive on the rinsed surfaces, for example on vehicles, particularly in wet weather.

It is sufficient for the solution of the problem to be added to the rinsing water only the polymer according to the invention. The polymer is particularly effective when the pH of the rinse water mixed with it is between 4.5 and 6.5, preferably between 5 and 6. Depending on the degree of neutralization of the polymer solution during its manufacture, these pH values can set themselves without further measures. If desired, the If the values are too high, the pH is adjusted with acid, the pH adjustment with organic hydroxycarboxylic acids, in particular with lactic acid, citric acid and / or tartaric acid, leading to particularly positive results.

For better wetting of the rinsed surfaces, it is preferred to continue adding small amounts of wetting agent, in particular nonionic surfactants, to the rinsing water. Ethylene oxide adducts with fatty alcohols or fatty chemical fatty alcohol mixtures with 10 to 16 carbon atoms and average degrees of ethoxylation of 8 to 15 mol ethylene oxide per mol fatty alcohol and corresponding ethoxylation products from CJO to cis fatty amines are particularly preferred for this. Addition products of an average of 12 moles of ethylene oxide per mole of fatty amines with mainly Cj2 and Cj4 components (coconut amine) are particularly suitable. Preferred concentrations of the nonionic surfactants in the polymer-containing rinse water are between 0.005 and 0.1% by weight, in particular between 0.01 and 0.05% by weight.

There are no special requirements for the application temperature of the rinsing water. In general, the final rinsing is carried out at the corresponding outside or room temperature, 4 to 40 ° C. and in particular 10 to 25 ° C. having proven to be a favorable temperature interval.

To facilitate handling, it is expedient to bring the polymer according to the invention to the place of use in the form of an aqueous concentrated solution and to meter it into the rinsing water in the desired concentration range. On the one hand, the polymer content of the concentrate is set as high as possible for reasons of economy of transport, on the other hand, the upper limit of the concentration is limited by the practical requirement for the concentrate to be pumpable. Polymer concentrations in the concentrate of 10 to 40% by weight have proven to be easy to handle. To stabilize and adjust the viscosity of the concentrate, it may be helpful to add alcohols with 2 to 4 carbon atoms in amounts of 0.01 to 20% by weight with respect to the concentrate. Isopropanol is preferred for this. It is further preferred to add the desired wetting agent and any hydroxycarboxylic acid required to the concentrates directly. The appropriate concentrations are between 0.5 and 2% by weight for the wetting agent and 0.001-1% by weight of hydroxycarboxylic acid, in each case based on the concentrate. For example, a concentrate according to the invention consists of 75% by weight of a 40% by weight aqueous polymer solution, 10% by weight of isopropanol, 1% by weight of wetting agent, 0.5% by weight of hydroxycarboxylic acid, the rest: VE -Water. For the purpose according to the invention, the concentrate is mixed into the rinse water in concentrations of between 0.5 and 2% by weight.

The invention thus relates to a further aspect

containing aqueous concentrate for use in the process according to the invention

10-40% by weight polymer

0.01 - 20 wt .-% alcohol with 2 to 4 carbon atoms

0.5 - 2 wt% wetting agent

0.001-1% by weight of hydroxycarboxylic acid, the rest of demineralized water.

As the experiments with comparative solutions showed, it is not sufficient for the solution of the object according to the invention to select the additives sought only according to their suitability as complexing agents for alkaline earth metal ions, since water rinsing residues generally dry out, even when complexing agents are present, and visible water stains or pads remain. Rather, an additive is required that binds the hardening agent ions and dries them together in the form of a uniform film that is not visible to the eye. Of course, this film must be removable the next time it is cleaned.

In spite of their known ability to form complexes with alkaline earth ions, polyacrylates without nitrogen-containing substituents are not suitable for solving the problem. Rather, they leave a clearly visible coating after drying. Execution examples

The following polymer solutions were prepared in accordance with DE-A-38 39 935, Examples 1 to 6:

example 1

Template solution:

41.8 parts by weight of water

0.1 part by weight of catalyst (2,2'-azobis (2-amidinopropane) dihydrochloride, feed solution 1:

16.9 parts by weight of dimethylaminoethyl methacrylate

16.9 parts by weight of methyl acrylate dissolution 2:

0.2 parts by weight of catalyst (as above)

2.0 parts by weight of water neutralization solution:

15.8 parts by weight of water approx. 6.3 parts by weight of phosphoric acid (85% strength) approx. 100.0 parts by weight of approx. 40% strength aqueous polymer solution

The production took place in a reaction vessel with stirrer, heating, cooling, reflux condenser, temperature measurement and two inlet vessels. The initial solution was first prepared from water and a catalyst in the reaction vessel. Feed solutions 1 and 2 were placed in separate feed vessels. The initial solution was heated to 75 ° C. with stirring. The two feed solutions were then added in parallel within 90 minutes, the temperature rising to 85 ° C. After the feed had ended, the reaction mixture was stirred at 80 ° C. for 60 min. After cooling to less than 45 ° C., the dispersion was adjusted to a pH of about 5.5 with the neutralizing solution. The reaction product was obtained in the form of a clear solution and a Brookfield viscosity of more than 5 Pa · s (spindle 4, 20 rpm); the dry residue was 40% (determined by evaporation in an oil pump vacuum at 80 ° C).

Example 2

Using the monomer units composed of 70% by weight of ethyl acrylate (EA) and 30% by weight of dimethylaminoethyl methacrylate (DMAEM), a 35% by weight aqueous preparation was neutralized with sulfuric acid analogously to Example 1.

Example 3

Using 70% by weight of diethylaminopropyl methacrylamide (DMAPAMA) and 30% by weight of ethyl acrylate (EA), a 30% by weight aqueous preparation was neutralized with glacial acetic acid analogously to Example 1.

Example 4

Using 85% by weight of dimethylaminopropyl methacrylamide (DMAPMA) and 15% by weight of butyl acrylate (BuA), a 30% by weight aqueous preparation was neutralized with formic acid / phosphoric acid (2: 5 parts by weight) analogously to Example 1.

Example 5

Using 80% by weight of dimethylaminoethyl methacrylate (DMAEM) and 20% by weight of methyl methacrylate (MMA), a 35% by weight aqueous preparation was neutralized with formic acid analogously to Example 1. Example 6

Using 40% by weight of dimethylaminoethyl methacrylate (DMAEM), 20% by weight of methyl methacrylate (MMA), 20% by weight of ethyl acrylate (EA) and 20% by weight of butyl acrylate (BuA), a 40% by weight was % aqueous preparation neutralized with phosphoric acid.

Concentrates 1 to 6 with the following composition were prepared from polymer solutions 1 to 6:

75% by weight polymer solution 10% by weight isopropanol 1% by weight wetting agent (adduct of 12 mol ethylene oxide with Ci2 / Ci4-cocosamine, = cocosamine x 12 E0) 0.4% by weight lactic acid Remainder demineralized water

Comparative solution 1

Solution according to DE-A-25 18 391 containing 30% by weight sodium lignosulfonate, 8% lactic acid, 3% by weight coconut amine x 12 E0, the rest: fully deionized water.

Comparative solution 2

Solution of 30% by weight maleic acid-acrylic acid (30:70) copolymer sodium salt (Sokalan ^R CP5, BASF AG), 10% by weight isopropanol, 1% by weight coconut amine x 12 E0, 0.5% by weight .-% lactic acid, rest: demineralized water.

Comparative solution 3 Solution of 70% by weight of a 45% by weight aqueous solution of acrylic acid polymer sodium salt (Degapas ^R 1105 N solution, DEGUSSA AG), 10% by weight of isopropanol, 1% by weight of coconut amine x 12 E0, 0.5% by weight lactic acid, remainder: demineralized water. Comparative solution 4

Solution of 30% by weight citric acid, 1% by weight coconut amine x 12 E0, 69% by weight deionized water, adjusted to pH 4.7 with 50% sodium hydroxide solution.

Attempted use

Rinsing water mixtures were prepared from concentrates 1 to 6 according to the invention and comparative solutions 1 to 4. For this purpose, synthetically hard water with hardness of 20 ° d and 28 ° d was produced from demineralized water, whereby the hardness consisted of half of carbonate hardness and half of sulfate hardness and as hardening agent cations Ca (II) and Mg ( II) were used in a weight ratio of 80:20. The water with a hardness of 20 ° d was mixed with a wt.%, The water with a hardness of 28 ° d with 2 wt.% Of the concentrates 1 to 6 or the comparison solutions 1 to 4. In the case of concentrate 1, the polymer-containing rinsing water had the pH values 5.3 (20 ° d) and 5.1 (28 ° d).

Glass plates and painted metal sheets were cleaned with an aqueous commercial cleaner (P3-glin ^R , Henkel KGaA) containing nonionic surfactants by wiping and stored horizontally. The polymer-containing rinsing water was sprayed onto the still moist surfaces at room temperature. The amount of rinse water sprayed was determined by weighing the plates. It was about 10 mg / cm ^ plate surface. The sprayed glass plates and sheets were allowed to air dry in a horizontal position, after which the surfaces were examined.

In the case of all rinsing water which contained the concentrates 1 to 6, the dried sheets had a uniform appearance without deposits and the glass plates were clearly transparent. When comparative solutions 1 to 4 were used, however, the dried sheets had a spotty, whitish coating, and the glass plates were streakily matt. If the water was mixed with hardness 28 ° d with 4% by weight of concentrates 1 to 6, the sheets sprayed as above had a matt appearance after drying due to the higher polymer film thickness. If only 0.5% by weight of concentrates 1 to 6 were added, visible water stains remained after drying.

Claims

claims

1. Use of copolymers containing amino groups, obtainable by copolymerizing, in each case based on polymer a) 15 to 90% by weight of one or more nitrogen-free monomers with an olefinic double bond and b) 10 to 85% by weight of one or more linear polymerizable monomers containing at least one tertiary amine function, diallylamine, 2-vinylpyridine and / or 4-vinylpyridine, the amino groups of the copolymers being neutralized or quaternized with acids until a clear water-soluble preparation has been achieved, as an additive to rinsing water after the cleaning of glass , Plastic, painted or metallic surfaces with aqueous solutions.

2. Use according to claim 1, characterized in that the nitrogen-free monomers are esters of acrylic or methacrylic acid with C1-C4 monoalkanols, optionally with a mixture with acrylic and / or methacrylic acid.

3. Use according to claim 1 or 2, characterized in that the monomers containing amino groups are esters of acrylic or methacrylic acid with a tertiary amino function having C2-Cö-monoalkanols and / or diethylamino compounds.

4. Use according to claim 1, 2 or 3, characterized in that the amino groups are neutralized with phosphoric acid.

5. Process for rinsing after cleaning glass, plastic, painted or metallic surfaces with water containing hardness-forming agents using the copolymers containing amino groups according to one or more of claims 1 to 4.

6. The method according to claim 5, wherein the polymer concentration in the Spülwas¬ water is 0.2 to 0.8 wt .-% and with a rinse water hardness up to 21 o'd. Concentrations between 0.2 and 0.4 wt .-% and at Rinse water hardness between 21 and 30 ° d concentrations between 0.4 and 0.8 wt .-% are preferred.

7. The method according to claim 6, wherein the pH of the rinse water solution is adjusted to 4.5 to 6.5, preferably to 5 to 6.

8. The method according to claim 7, wherein organic hydroxycarboxylic acids, in particular lactic acid, citric acid and / or tartaric acid are used for pH adjustment.

9. The method according to one or more of claims 5 to 8, wherein the rinsing water solution wetting agent, preferably from the class of non-ionic surfactants, in concentrations between 0.005 and 0.1 wt .-%, preferably between 0.01 and 0.05 , contains.

10. Aqueous concentrate for use in the process according to one or more of claims 5 to 9, containing

10-40% by weight polymer

0.01 - 20 wt .-% alcohol with 2 to 4 carbon atoms

0.5 - 2 wt% wetting agent

0.001 - 1 wt.% Hydroxycarboxylic acid remainder fully demineralized water.