EP1682645A1

EP1682645A1 - Use of copolymers, containing alkylene oxide units, as deposit inhibitor additives in the rinsing process of a dishwasher

Info

Publication number: EP1682645A1
Application number: EP04790785A
Authority: EP
Inventors: Marcus Guzmann; Heike Becker
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2003-10-28
Filing date: 2004-10-23
Publication date: 2006-07-26
Anticipated expiration: 2024-10-23
Also published as: ATE422533T1; EP1682645B1; US20070082831A1; WO2005042684A1; DE10350420A1; US7530360B2; CA2543543A1; DE502004008984D1; ES2318349T3; JP2007510021A

Abstract

Use of copolymers comprising alkylene oxide units and comprising, in randomly or blockwise copolymerized form, (a) 50 to 93 mol % of acrylic acid and/or a water-soluble salt of acrylic acid, (b) 5 to 30 mol % of methacrylic acid and/or a water-soluble salt of methacrylic acid and (c) 2 to 20 mol % of at least one nonionic monomer of the formula I in which the variables have the following meanings: R1 is hydrogen or methyl; R2 is a chemical bond or unbranched or branched C1-C6-alkylene; R3 is identical or different unbranched or branched C2-C4-alkylene radicals; R4 is unbranched or branched C1-C6-alkyl; n is 3 to 50, as deposit-inhibiting additives in the rinsing cycle of a dishwasher.

Description

Use of copolymers containing alkylene oxide units as scale-inhibiting additives in the rinse cycle of automatic dishwashers

description

The present invention relates to the use of copolymers containing alkylene oxide units which

(a) 50 to 93 mol% of acrylic acid and / or a water-soluble salt of acrylic acid,

(b) 5 to 30 mol% of methacrylic acid and / or a water-soluble salt of methacrylic acid and

(c) 2 to 20 mol% of at least one nonionic monomer of the formula I.

R ¹ I 2 H ₂ C = C - COO - RH-RO- -R ⁴ in which the variables have the following meaning:

R ^{1 is} hydrogen or methyl; R ^{2 is} a chemical bond or unbranched or branched CC ₆ alkylene; R ^{3 are the} same or different unbranched or branched C ₂ -C ₄ alkylene radicals; R ⁴ unbranched or branched n 3 to 50,

randomly or block-copolymerized, as deposit-inhibiting additives in the rinse cycle of the automatic dishwasher.

In addition, the invention relates to rinse aid for automatic dishwashers which contain these copolymers as a deposit-inhibiting additive and detergent tablets for automatic dishwashers which contain the copolymers formulated in the rinse aid core as a deposit-inhibiting additive.

In the case of automatic dishwashing, the dishes should be cleaned in a residue-free state with an immaculately shiny surface. The wash ware should not should only be completely cleaned of food residues and should not show any whitish stains caused by the presence of lime or other inorganic and organic salts when water droplets dry out.

For this reason, rinse aid has been used for a long time. The rinse aid is automatically dispensed from the dosing tank into the interior of the dishwasher in the final rinse cycle after passing through the cleaning program, which usually consists of a pre-rinse cycle and a main rinse cycle that is interrupted by intermediate rinse cycles, and ensures that the water flows out of the washware flatly and as completely as possible during the rinse cycle and drying cycle and the washware surfaces are residue-free and flawlessly shiny at the end of the wash program.

In the so-called "2-in-1" detergents introduced on the market, rinse aid surfactants are already integrated in the detergent formulation, so that the additional dosing of a rinse aid can be avoided.

Modern machine "3in1" cleaners combine the three functions of cleaning, rinsing and water softening in a single detergent formulation, so that the refill of salt with water hardness of 1 to 3 is also superfluous for the consumer. Sodium tripolyphosphate is usually added to these cleaners to bind the hardness-forming calcium and magnesium ions. This in turn results in calcium and magnesium phosphate deposits on the wash ware.

The object of the invention was to provide polymeric additives which, when used in the rinse aid of an automatic dishwasher, are notable for their deposit-inhibiting action.

Accordingly, the use of alkylene oxide-containing copolymers which

(b) 5 to 30 mol% of methacrylic acid and / or a water-soluble salt of methacrylic acid and, 1 RH ₂ C = C - COO - R ² -hR-0 n in which the variables have the following meaning:

R ^{1 is} hydrogen or methyl; R ^{2 is} a chemical bond or unbranched or branched CC ₆ alkylene; R ^{3 are the} same or different unbranched or branched C ₂ -C ₄ alkylene radicals; R ⁴ unbranched or branched C ₁ -C ₆ alkyl; n 3 to 50,

copolymerized randomly or in blocks, found as deposit-inhibiting additives in the rinse cycle of the automatic dishwasher.

In addition, rinse aids for automatic dishwashers have been found which contain these copolymers as a deposit-inhibiting additive.

Detergent tablets for automatic dishwashers have also been found which contain these copolymers as a deposit-inhibiting additive formulated in the rinse aid core.

The copolymers to be used according to the invention are described in the unpublished DE-A-102 25 594 as an additive to detergents and cleaning agents.

The copolymers containing alkylene oxide units to be used according to the invention contain, as copolymerized components (a) and (b), acrylic acid or methacrylic acid and / or water-soluble salts of these acids, in particular the alkali metal salts, such as potassium and especially sodium salts, and ammonium salts.

The proportion of acrylic acid (a) in the copolymers to be used according to the invention is 50 to 93 mol%, preferably 65 to 85 mol% and particularly preferably 65 to 75 mol%.

The copolymers to be used according to the invention contain 5 to 30 mol% of methacrylic acid (b), preferably 10 to 25 mol% and especially 15 to 25 mol%.

The copolymers contain, as component (c), nonionic monomers of the formula I.

R ¹ H ₂ C = C - COO - R- -RO- - n R ^* in which the variables have the following meaning:

R ^{1 is} hydrogen or preferably methyl; R ² unbranched or branched CrCe alkylene or preferably a chemical bond; R ^{3 are the} same or different unbranched or branched C ₂ -C ₄ alkylene radicals, especially C ₂ -C ₃ alkylene radicals, especially ethylene; R ⁴ unbranched or branched Ci-Ce alkyl, preferably C ₁ -C ₂ alkyl; n 3 to 50, preferably 5 to 40, particularly preferably 10 to 30.

The following may be mentioned as particularly suitable examples of the monomers II: methoxypolyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, methoxypolybutylene glycol (meth) acrylate, methoxypoly (propylene oxide-co-ethylene oxide) (meth) acrylate, ethoxypolyethylene glycol ( meth) acrylate, ethoxypolypropylene glycol (meth) acrylate, ethoxypolybutylene glycol (meth) acrylate and ethoxypoly (propylene oxide-co-ethylene oxide) (meth) acrylate, methoxypolyethylene glycol (meth) acrylate and methoxypolypropylene glycol (meth) acrylate being preferred and methoxypolyethylene glycol methacrylate being particularly preferred is.

The polyalkylene glycols contain 3 to 50, especially 5 to 40 and especially 10 to 30 alkylene oxide units.

The proportion of nonionic monomers (c) in the copolymers to be used according to the invention is 2 to 20 mol%, preferably 5 to 15 mol% and especially 5 to 10 mol%.

The copolymers to be used according to the invention generally have an average molecular weight M _w of 3,000 to 50,000, preferably 10,000 to 30,000 and particularly preferably 15,000 to 25,000.

The K value of the copolymers is usually 15 to 40, in particular 20 to 35, especially 27 to 30 (measured in 1% strength by weight aqueous solution at 25 ° C., according to H. Fikentscher, cellulose chemistry, Vol. 13, pp. 58-64 and 71-74 (1932)).

The copolymers to be used according to the invention can be produced by radical polymerization of the monomers. All known radical polymerization processes can be used. In addition to bulk polymerization, the methods of solution polymerization and emulsion polymerization should be mentioned in particular, with solution polymerization being preferred. The polymerization is preferably carried out in water as a solvent. However, it can also be carried out in alcoholic solvents, in particular CrC ₄ alcohols, such as methanol, ethanol and isopropanol, or mixtures of these solvents with water.

Compounds which decompose thermally and photochemically (photoinitiators) and thereby form free radicals are suitable as polymerization initiators.

Among the thermally activatable polymerization initiators, initiators with a decomposition temperature in the range from 20 to 180 ° C., in particular from 50 to 90 ° C., are preferred. Examples of suitable thermal initiators are inorganic peroxo compounds, such as peroxodisulfates (ammonium and preferably sodium peroxodisulfate), peroxosulfates, percarbonates and hydrogen peroxide; organic peroxo compounds, such as diacetyl peroxide, di-tert.-butyl peroxide, diamyl peroxide, dioctanoyl peroxide, didcanoyl peroxide, dilauroyl peroxide, dibenzoyl peroxide, bis (o-toloyl) peroxide, succinyl peroxide, tert.-butyl peryl acetate, tert.-butyl acetate .-Butyl perisobutyrate, tert.-butyl perpivalate, tert.-butyl peroctoate, tert.-butyl pemeodecanoate, tert.-butyl perbenzoate, tert.-butyl peroxide, tert.-butyl hydroperoxide, cumene hydroperoxide, tert.-butyl peroxi-2-ethylhexyl peroxide and hexanoate ; Azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile) and azobis (2-amidopropane) dihydrochloride.

These initiators can be used in combination with reducing compounds as starter / controller systems. Examples of such reducing compounds include phosphorus-containing compounds, such as phosphorous acid, hypophosphites and phosphinates, sulfur-containing compounds, such as sodium bisulfite, sodium sulfite and sodium formaldehyde sulfoxilate, and hydrazine.

Examples of suitable photoinitiators are benzophenone, acetophenone, benzoin ether, benzyl dialkyl ketones and their derivatives.

Thermal initiators are preferably used, inorganic peroxo compounds, in particular sodium peroxodisulfate (sodium persulfate), being preferred. The peroxo compounds are used particularly advantageously in combination with sulfur-containing reducing agents, in particular sodium bisulfite, as the redox initiator system. When this starter / regulator system is used, copolymers are obtained which contain -SO ₃ ^" Na ^* and / or -SO ₄ ^' Na ⁺ as end groups and are distinguished by a particular coating-inhibiting effect.

Alternatively, starter / regulator systems containing phosphorus can also be used, for example hypophosphites / phosphinates. The quantities of photoinitiator and starter / regulator system must be matched to the substances used. If, for example, the preferred system peroxodisulfate / hydrogen sulfite is used, 2 to 6% by weight, preferably 3 to 5% by weight, of peroxodisulfate and usually 5 to 30% by weight, preferably 5 to 10% by weight are used .-%, hydrogen sulfite, each based on the monomers (a), (b) and (c), used.

If desired, polymerization regulators can also be used. The compounds known to the person skilled in the art, e.g. Sulfur compounds such as mercaptoethanol, 2-ethylhexylthioglycolate, thioglycolic acid and dodecyl mercaptan. If polymerization regulators are used, the amount used is generally 0.1 to 15% by weight, preferably 0.1 to 5% by weight and particularly preferably 0.1 to 2.5% by weight, based on the monomers (a), (b) and (c).

The polymerization temperature is generally 30 to 200 ° C, preferably 50 to 150 ° C and particularly preferably 80 to 120 ° C.

The polymerization can be carried out under atmospheric pressure, but is preferably carried out in a closed system under the self-developing pressure.

The monomers (a), (b) and (c) can be used as such in the preparation of the copolymers to be used according to the invention, but reaction mixtures which are obtained in the preparation of the monomers (c) can also be used. For example, instead of methoxypolyethylene glycol methacrylate, the monomer mixture obtained in the esterification of polyethylene glycol monomethyl ether with an excess of methacrylic acid can be used. The esterification can advantageously also be carried out in situ in the polymerization mixture by combining (1) acrylic acid, (2) a mixture of methacrylic acid and polyethylene glycol monomethyl ether and (3) radical initiators in parallel. If necessary, a catalyst required for the esterification, such as methanesulfonic acid or p-toluenesulfonic acid, can additionally be used.

The copolymers to be used according to the invention can also be obtained by a polymer-like reaction, e.g. by reacting an acrylic acid / methacrylic acid copolymer with polyalkylene glycol monoalkyl ether. However, the radical copolymerization of the monomers is preferred.

If desired for the application, the aqueous solutions obtained in the preparation of the copolymers containing carboxylic acid groups to be used according to the invention can be neutralized by adding base, in particular sodium hydroxide solution or partially neutralized, ie adjusted to a pH in the range 4-8, preferably 4.5-7.5.

The copolymers used according to the invention are notable for their outstanding deposit-inhibiting action when used in the rinse aid of automatic dishwashers.

They have an inhibiting effect on both inorganic and organic coatings. In particular, coverings are caused by the components of the detergent formulation carried over into the rinse cycle by the "carry-over effect", such as coverings of calcium and magnesium phosphate, calcium and magnesium silicate and calcium and magnesium phosphonate, and coverings resulting from the Dirt constituents of the washing liquor originate, such as fat, protein and starch deposits. The copolymers to be used according to the invention sustainably improve the cleaning result due to their deposit-inhibiting effect. In addition, they promote the drainage of the water from the wash ware, even in low concentrations, so that the proportion of rinse aid surfactants in the dishwashing detergent can be reduced. Accordingly, particularly clear glasses and high-gloss metal cutlery are obtained, especially when the dishwasher is operated without water regeneration salt for water softening.

The copolymers used according to the invention can be used directly in the form of the aqueous solutions obtained in the preparation and also in dried, e.g. form obtained by spray drying, fluidized spray drying, roller drying or freeze drying.

The copolymers according to the invention can advantageously be used in particular as follows:

- Dissolved in a rinse aid formulation that is automatically dosed in the dishwasher at the beginning of the rinse cycle.

Formulated in the rinse aid core of a dishwasher detergent tablet, from which they are specifically released in the rinse aid cycle.

As a solid obtained by one of the processes described above, which is additionally provided with a coating which is soluble under the rinse aid conditions (temperature, pH value, residual concentration of detergent components in the rinse aid) or is built into a matrix which is soluble under these conditions, together with the detergent in the machine is brought in and is only released in the rinse cycle. Suitable coating material for this purpose is, for example, polyvinyl alcohol produced by incomplete hydrolysis of polyvinyl acetate (degree of hydrolysis generally from 88 to 98%, preferably 89 to 95%, particularly preferably 91 to 92%).

Suitable matrix materials are, for example, gelatin, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, cellulose and their derivatives, starch and their derivatives and mixtures of these materials.

Examples

A) Manufacturing

example 1

In a reactor with nitrogen supply, reflux condenser and metering device, a mixture of 619 g of distilled water and 2.2 g of phosphorous acid was heated to 100 ° C. internal temperature with nitrogen supply and stirring. Then in parallel (1) a mixture of 123.3 g acrylic acid and 368.5 g distilled water, (2) a mixture of 18.4 g sodium peroxodisulfate and 164.6 g distilled water, (3) a mixture of 72.0 g of water, 49.1 g of methacrylic acid and 166.9 g of methoxypolyethylene glycol methacrylate (M _w = 1100) and (4) 46 g of a 40% by weight aqueous sodium bisulfite solution were added continuously in 5 h. After stirring for two hours at 100 ° C., the reaction mixture was cooled to room temperature and adjusted to a pH of 7.2 by adding 190 g of 50% strength by weight sodium hydroxide solution.

A slightly yellowish, clear solution of a copolymer with a solids content of 25.7% by weight and a K value of 27.2 (1% by weight aqueous solution, 25 ° C.) was obtained.

B) Use in machine dishwashing

B1) Simulating a 3in 1 dishwashing formulation with additional copolymer release in the rinse cycle

To test its rinse aid effect, the copolymer according to the invention was used together with a commercially available 3in1 dishwashing formulation in tablet form (Saturday), the copolymer only being added in the rinse cycle in order to simulate a delayed release of further copolymer.

The test was carried out under the following washing conditions with the addition of IKW ballast dirt (SÖFW-Journal, 124th year, 14/98, p. 1029) in the main washing cycle and made in addition to the copolymer in the rinse aid. In addition, neither regenerated salt nor rinse aid formulation was used.

Rinsing conditions: Dishwasher: Miele G 686 SC Rinses: 1 rinse 55 ° C normal (without pre-rinsing) Wash items: Knives (WMF table knife Berlin, monoblock); Glasses (Willy Becher, 0.3 I); black plastic plates, black dessert plates; EMSA Superline Box (lid PE blue, PP can transparent) Dishwashing liquid: Somat 3 in 1 ballast dirt: 50 g in the main wash cycle; 2 g in the rinse aid copolymer: 210 mg in the rinse aid rinse temperature: 65 ° C

Water hardness: 21 ° dH

At the end of the wash cycle, the door was opened and the dishes were left to dry for 60 minutes with the machine door open. The items to be washed were then assessed by visual inspection in a black-painted light box with a halogen spot and pinhole using a grading scale of 0 (very poor, very strong formation of dried drops (spotting), ie more than 50% of the surface covered with spots, very strong formation of flat coverings (filming) to 4 (very good, no spots, no filming). The test results obtained are summarized in Table 1, the results being shown without the addition of copolymer for comparison.

Table 1

B2) Use in a rinse aid formulation

To test the rinse aid effect in the rinse aid, the copolymer was added directly to the rinse aid formulation. The test was carried out under the conditions specified below with the addition of IKW ballast soiling in the main and rinse cycle.

The following formulation was used as the cleaner:

50% by weight sodium tripolyphosphate (Na ₃ P ₃ O ₁₀ 6 H ₂ O)

27% by weight sodium carbonate 3% by weight sodium disilicate (x Na ₂ 0 y SiO ₂ ; x / y = 2.65; 80% by weight) 6% by weight sodium percarbonate (Na ₂ CO ₃ 1, 5 H ₂ O) 2% by weight tetraacetylethylenediamine (TAED) 2% by weight low-foaming nonionic surfactant based on fatty alcohol alkoxylates 3% by weight sodium chloride 5% by weight sodium sulfate 2% by weight polyacrylic acid sodium salt (M. _w 8 000)

The copolymer was used in the following rinse aid formulation:

20% by weight low-foaming nonionic surfactant based on fatty alcohol alkoxylates 10% by weight sodium cumene sulfonate (40% by weight) 5% by weight isopropanol 4% by weight copolymer (active substance) 61% by weight water

The following rinsing conditions were used:

Dishwasher: Miele G 686 SC

Rinses: 1 rinse 55 ° C normal (without pre-rinsing)

Items to be washed: Knives (WMF table knife Berlin, monoblock); Glasses (Willy Becher, 0.3 I); black plastic plates, black dessert plates; EMSA Superline box (lid PE blue, PP box transparent)

Dishwashing liquid: 21 g

Ballast dirt: 50 g in the main wash cycle; 2 g rinse aid

Rinse aid temperature: 65 ° C

Rinse aid dosage: i g

Water hardness: 3 ° dH At the end of the wash cycle, the door was opened and the dishes were left to dry for 60 minutes with the machine door open. The items to be washed were then assessed by visual inspection in a black-painted light box with halogen spotlight and pinhole using the scale 0 to 4 described above.

The test results obtained are summarized in Table 2, the results being shown without the addition of copolymer for comparison. Table 2

Claims

claims

1. Use of copolymers containing alkylene oxide units, the

(c) 2 to 20 mol% of at least one nonionic monomer of the formula I.

R ¹ HC = C - COO - R-τ-RO ^ rR ⁴ I in which the variables have the following meaning:

R ^{1 is} hydrogen or methyl; R ^{2 is} a chemical bond or unbranched or branched dC ₆ alkylene; R ^{3 are the} same or different unbranched or branched C ₂ -C ₄ alkylene radicals; R ⁴ unbranched or branched CC ₆ alkyl; n 3 to 50, statistically or block-copolymerized, as deposit-inhibiting additives in the rinse cycle of the automatic dishwasher.

2. Use according to claim 1, characterized in that the copolymers contain 65 to 85 mol% of component (a), 10 to 25 mol% of component (b) and 5 to 15 mol% of component (c) in copolymerized form ,

3. Use according to claim 1 or 2, characterized in that the copolymers 65 to 75 mol% of component (a), 15 to 25 mol% of component (b) and 5 to 10 mol% of component ( c) copolymerized.

4. Use according to claims 1 to 3, characterized in that the copolymers as component (c) is a nonionic monomer of the formula I in which R ^{1 is} methyl, R ^{2 is} a chemical bond, R ³ C ₂ -C ₃ alkylene, R ^{4 is} CC ₂ alkyl and n is 5 to 40, contained in copolymerized form.

5. Use according to claims 1 to 4, characterized in that the copolymers as component (c) is a nonionic monomer of the formula I in which R ^{1 is} methyl, R ^{2 is} a chemical bond, R ^{3 is} ethylene, R ^{4 is} methyl and n 10 up to 30, contain copolymerized.

6. Use according to claims 1 to 5, characterized in that the copolymers contain -SO ₃ ^" Na ⁺ and / or -SO ₄ ^" Na ⁺ as end groups.

7. Use according to claims 1 to 6, characterized in that the copolymers are used in rinse aid for automatic dishwashers.

8. Use according to claims 1 to 6, characterized in that the copolymers are used formulated in the rinse aid core of a detergent tablet for machine dishwashers.

9. rinse aid for automatic dishwashers, which contain copolymers according to claims 1 to 6 as a deposit-inhibiting additive.

10. Detergent tablets for automatic dishwashers, which contain copolymers according to claims 1 to 6 formulated as a deposit-inhibiting additive in the rinse aid.