SK552000A3 - Use of polyelectrolytes as sequestering agents - Google Patents

Abstract

The invention relates to the use of a polyelectrolytes as sequestering agents for producing aqueous bleaching agents. According to the invention, it is possible to obtain preparations which protect the fabric from yellowing, preferably chlorine bleaching solutions, especially together with buffers and chlorine-resistant tensides.

Description

Use of polyelectrolytes as sequestering agents

Technical field

The invention relates to the use of polyelectrolytes as sequestering agents in the manufacture of aqueous bleaching compositions.

BACKGROUND OF THE INVENTION

While in many European countries, washing of heavily soiled fabrics uses powdery or liquid detergents whose performance is only achieved at higher temperatures, consumers in the US and Spain, for example, prefer cold washing where they are added to the wash to remove very difficult stains and a bleaching agent, in particular based on hypochlorite.

Many liquid bleaching agents are known in the art. For example, EP-A-0274885 (ICI) recommends the use of a mixture of linear and branched amine oxides in the manufacture of viscous hypochlorite bleaching compositions. According to the teaching of EP-A 0145084 (Unilever), mixtures of amine oxides with soaps, sarcosinates, taurides or sugar esters can also be used for this purpose. EP-A-0137551 and EP-A-0447261 (Unilever) disclose the use of amine oxides with a soap or sarcosinate and other anionic surfactants, for example alkyl sulfates, alkyl ether sulfates, secondary alkanesulfonates or alkyl benzene sulfonates as a thickening agent for the thickening agent. Further, EP-A1 0447261 discloses aqueous bleaching compositions containing sodium hypochlorite and anionic surfactants. However, the hypochlorite concentration in this composition is 0.1 to 8 wt. of active chlorine. In German patent DE-C1 4333100, the applicant finally proposes chlorine bleaching liquors based on hypochlorite, fatty alcohol ether sulfates, amine oxides and amine oxide phosphonic acids. Use of silicates or carbonates as a buffer in chlorine bleaching

For example, U.S. Pat. No. 4,623,476 (Procter & Gamble) as well as EP-A1 0079102 and EP-A1 0137551 (Unilever).

Consumers have high demands on a bleaching composition of this kind: they must be compatible with textiles, i.e. treatment with aggressive hypochlorite chemicals must remove stains without breaking the fabric. Since skin contact with the bleaching agent is not excluded, the preparations must be as dermatologically compatible as possible. A particular problem is that hypochlorite solutions also attack metals and the dissolved traces of metals can settle on the fibers of the fabric during washing, which can subsequently cause the fabric to yellow. Although preparations on the market attempt to prevent such deposition by the common use of silicates, in practice this measure is not always satisfactory.

Consequently, the complex object of the present invention was to counteract the yellowing of laundry by heavy metal ions and to provide a sequestering agent allowing the production of aqueous bleaching agents, in particular chlorine-free bleaching liquids, which protect textiles and are preferably

Even skin-friendly, they have a sufficiently high viscosity and reliably prevent metal traces from settling on the fabric with high stain removal capability.

SUMMARY OF THE INVENTION

The present invention is based on the use of polyelectrolytes as sequestering agents in the manufacture of aqueous bleaching compositions.

Surprisingly, it has been found that the addition of a small amount of polyelectrolytes to an aqueous bleaching agent, in particular to a hypochlorite solution, significantly reduces the deposition of metals on the fabric during washing and counteracts the yellowing of the fibers. The invention includes the finding that the combined use of buffers such as, in particular, silicates, carbonates and / or phosphonates, as well as optionally fine, chlorine-stable surfactants such as, in particular, alkyl ether sulfates, amine oxides, alkyl and / or alkenyloligoglycosides and fatty acid salts further improve stability yellowing, cleansing performance and dermatological tolerance.

The compositions of the invention also have a sufficiently high viscosity such that consumer dosing is problem-free.

polyelectrolyte

(a) Low molecular weight dicarboxylic acids

In the simplest case, low molecular weight dicarboxylic acids of formula i may be used as polyelectrolytes,

ROOC (CH ₂ ) _n OOCR ² (I) wherein R ¹ and R ² are hydrogen, an alkali metal and / or an alkaline earth metal, ammonium, alkylammonium, alkanolammonium or glucammonium and n is a number from 0 to 64. Typical examples are oxalic acid malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid as well as dimers and trimers of fatty acids based on unsaturated fatty acids, namely oleic acid, elaidinoic acid, gadoleic acid and erucic acid. The dicarboxylic acids may be mono- or polyunsaturated and / or may have an aromatic ring in place of the alkenyl group. Typical examples are maleic acid, fumaric acid, sorbic acid, phthalic acid and terephthalic acid. Neutralization occurs when these acids are introduced into the alkaline bleaching composition. However, they can also be used in the form of their salts, more preferably sodium salts. The use of adipic acid or sodium adipate as a polyelectrolyte is highly preferred.

b) Low molecular weight polycarboxylic acids

Typical examples of suitable polyhydric hydroxycarboxylic acids are malic acid, tartaric acid, and especially citric acid. It is also possible to use these acids in the form of their alkali and / or alkaline earth salts, ammonium, alkylammonium, alkanolammonium or glucamonic salts. It is particularly preferred to use citric acid or sodium citrate as the polyelectrolyte.

-4c) Mono- and copolymers of unsaturated monocarboxylic acids and their esters Suitable monomers have the formula II,

CH ₂ = CR ³ (CH ₂ ) _m COOR ⁴ . (II) wherein R ³ is hydrogen or methyl, R ⁴ is hydrogen or a linear or branched hydrocarbon radical having 1 to 22, more preferably 2 to 12 and especially 3 to 8 carbon atoms and m is a number from 0 to 10. Typical examples are acrylic and / or methacrylic acid as well as their esters with methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, capro alcohol, caprylalcohol, 2-ethylhexyl alcohol, isopropyl alcohol, caprinal alcohol, caprinal alcohol, , palmoleyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, elaidyl alcohol, petroselinyl alcohol, linolyl alcohol, linolenyl alcohol, elaeostearyl alcohol, arachyl alcohol, gadoleyl alcohol, behenyl alcohol, bucolyl esters, such as bucyl alcohol and brassyl esters from fats and oils or from aldehydes in Roelen oxosynthesis. Preference is given to using homo- or copolymers of acrylic acid, methacrylic acid and their methyl, tert-butyl or 2-ethylhexyl esters. The resulting polymers may have an average molecular weight in the range from 300 to 5,000,000, more preferably from 10,000 to 1,000,000, in particular from 50,000 to 500,000, and in particular from 100,000 to 250,000 Daltons. This preferred molecular weight distribution also applies to the other groups of suitable polymeric sequestering agents. Typical examples of suitable homo- and copolymers of acrylic and methacrylic acid having a molecular weight of from 5,000 to 15,000 daltons are given in DE-OS 1808824 (Grace). Polymers produced in the presence of sulfur compounds such as thioglycolic acid or 2-mercaptoethanol are also particularly suitable [cf. US 3665035 and US 3787488 (Magna)]. Equally suitable are homo- and copolymers produced by the method of DE-AS 2632773 (Ciba). The thioether groups formed in the polymerization are subsequently oxidized to the sulfoxide groups

-5a / or sulfone groups. Suitable polymers of acrylic acid / acrylic acid esters containing sulfur with hydrophobic moieties are also the subject of US 4008164 (Nalco). It is also possible to use hydroxyl-containing polymers which are produced, for example, by copolymerization of acrylic acid with acrolein and subsequent disproportionation [cf. DE-AS 2522637]. Copolymers of methacrylic acid with vinyl sulfonic acid are also known from US 3682224 (Bleyle). Other suitable polyacrylates or polymethacrylates are described in the following literature: GB-A1 1034680 (Commonwealth Scientific), NL-A 7400160 (Grace), BEA 620771 (Cyanamide), and US 3516916 (Grace).

d) Homo- and copolymers of unsaturated dicarboxylic acids and derivatives thereof

The unsaturated dicarboxylic acids which may be considered as monomers are already mentioned under a). However, because of the high reactivity and low cost, the use of maleic anhydride is preferred. Products made, for example, by hydrolysis of polymaleic anhydride have a high charge intensity. The ring structure, which results from side reactions during polymerization, additionally gives the molecules a certain chain stiffness, which has an advantageous separation effect. Polymaleic acid anhydrides (PMSA) having a molecular weight in the range of from 300 to 5000 daltons are known, for example, from US 3810835 (Ciba). Copolymers of PMSA and poly (meth) acrylic acid having a molecular weight ranging from 1000 to 50,000 are disclosed in DE-AS 2412926 (Ciba). US 3650970 (Atlantic Richfield) discloses copolymers of maleic anhydride and styrene, which are subjected to ring opening by polyethylene glycol (molecular weight 300 to 1000) and also have a good sequestering effect. The same applies to copolymers of maleic anhydride with sulfonated styrene [FR-A 2322831 (Betz)], with vinyl acetate [US 3755264 (Amicon)], methacrylic acid / styrene [US 4065607 (Pfitzner)], allyl acetate [US 4001134 (Grace)] and / or acrolein [DE-AS 2404192 (Ciba)].

e) Homo- and copolymers of unsaturated monocarboxylic acid amides and derivatives thereof

The group of these substances is in particular compounds which have been produced either by (co) polymerization of monomers or by polymer analog hydrolysis of poly (meth) acrylamide or poly (meth) acrylonitrile. The production of polyacrylamide having a molecular weight ranging from 500 to 5,000 daltons using thioglycolic acid as a regulator and alkaline hydrolysis of 60 to 90% amide groups is described, for example, in US 4001161 (Cyanamide). A polymer of similar composition is obtained according to US 3492240 (Nalco). The product contains 20 to 50% amide groups and 50 to 80% carboxyl groups and has a molecular weight ranging from 20,000 to 40,000. From CA 982341 (Nalco) a hydrolyzed polyacrylonitrile is also known which contains 20 to 30% amide groups. up to 80% of acid groups and has a molecular weight of from 5000 to 40,000. Also suitable are grafted polymers of acrylamide or acrylonitrile on starch or vinyl alcohol, as well as their hydrolysis products [cf. NL 66/5265 (ICI)].

f) Other anionic or cationic polyelectrolytes

In addition to the abovementioned substances, the following substances are suitable polyelectrolytes: poly- (N, N-bis-carboxymethylene acrylamide) [cf. GB-A 1310613 (Chemed)], copolymers of fumaric acid and vinyl sulfonic acid [cf. US 3879288, US 3706717 (Siegele)], 3-acrylamido-3-methylpropanesulfonic acid polymers [cf. US 3709815, US 3928196 (Calgon)], copolymers of acrylic acid and styrene sulfonic acid [cf. US 4048066 (Chemed)], acrylic acid copolymers with 2-hydroxyethyl methacrylate monophosphate [cf. JA-A 76/112447 (Sanyo)], homo- and copolymers of 3-acrylamido-3-methylbutyl-trimethylammonium chloride ¹ '[cf. US 3752761 (Calgon)], diallyl glycine amide hydrochloride-acrylic acid copolymers [cf. US 3574175 (Grace)], dimethylallylammonium chloride-acrylamide copolymers [cf. GB-A 1287489], polyethylene and / or propyleneimines [cf. GB-A 1015612 (Grace)], and mixtures thereof.

Alkaline hypochlorites

Aqueous bleaching solutions may contain hydrogen peroxide, but are preferably chlorine bleaching liquors containing alkali hypochlorite.

Alkaline hypochlorite means lithium, potassium and especially sodium hypochlorite. The hypochlorites can be used in amounts of from 1.5 to 10, preferably from 2 to 8, and in particular from 4 to 6% by weight. relative to the device.

Buffer solutions

In a more preferred embodiment, the polyelectrolytes are used in combination with buffers which are alkali silicates, carbonates, phosphonates and / or alkaline earths, or mixtures thereof. These salts promote the separating effect of the polyelectrolytes and ensure that the pH of the formulation is constant, highly alkaline in the range of 10 to 14. Typical examples are sodium silicate, potassium silicate, sodium carbonate, potassium carbonate as well as phosphonates, especially amine oxide phosphonic acid. Sequion® from Bozetto / IT. The buffers may be used alone or in a mixture in amounts of from 0.01 to 5, in particular from 0.1 to 2, in particular from 0.5 to 1% by weight. - relative to the device.

Chlorine stable surfactants

(a) Alkyl ether sulphates

Alkyl ether sulfates are known anionic surfactants which can be obtained by sulfating nonionic surfactants of the alkyl polyglycol ether type and subsequent neutralization. In the composition according to the invention, the suitable alkyl ether sulfates have the formula III,

R ⁵ O- (CH ₂ CH ₂ O) _q SO ₃ X (III) wherein R ⁵ represents an alkyl radical having 12 to 18, more preferably 12 to 14 carbon atoms, q is a number from 2 to 5, in particular 2 to 3, and X represents sodium or potassium. Typical examples are the sodium salts of the C _12/14 -cocoalcohol-2,3-and-EO-adduct sulphates. The alkyl ether sulfates may have a conventional or narrow distribution of homologs. It is preferred to use alkyl ether sulfates in an amount of from 1 to 8, more preferably 1.5 to 6, and especially 2 to 4 wt. relative to the device.

-8b) Amine oxides

Also, amine oxides are known substances which are occasionally ranked as cationic, but generally nonionic surfactants. They are prepared from tertiary fatty amines, which generally have either one long or two short or two long and one short alkyl radicals and are oxidized in the presence of hydrogen peroxide. Within the meaning of the invention, the amine oxides to be considered have the formula IV,

R ⁷

I

R - N -> O (IV)

I

R ⁸ wherein R ⁶ represents a linear or branched alkyl radical having 12 to 18 carbon atoms as well as R ⁷ and R ⁸ independently of one another R ⁶ or an alkyl radical having 1 to 4 carbon atoms optionally hydroxy-substituted. Preference is given to the use of amine oxides of the formula IV in which R @ 8 and R @ ⁷ are C12 / 14 or C12 / 18-cocosalkyl and R @ ⁸ is a methyl or hydroxyethyl radical. Equally preferred are amine oxides of formula IV wherein R @ 6 is C12 / 14 or C _12/18 -cocoalkyl and R ⁷ and R ⁸ are methyl or hydroxyethyl. The amine oxides are usually used in an amount of from 1.5 to 6, preferably from 2 to 4% by weight. relative to the device.

c) Alkyl- and / or alkenyloligoglycosides

Alkyl and alkenyl oligoglycosides are known nonionic surfactants having the formula V,

R ⁹ O- [G] _P (V) wherein R ⁹ represents an alkyl and / or alkenyl radical having 4 to 22 carbon atoms, G is a sugar radical having 5 or 6 carbon atoms and is a number from 1 to 10. obtained by appropriate preparative organic procedure

-9chémie. Representative for the extensive literature is referred to EP-A1 0301298 and WO 90/03977. The alkyl and / or alkenyl oligoglycosides can be derived from aldoses or ketoses having 5 or 6 carbon atoms, in particular glucose. Preferred alkyl and / or alkenyloligoglycosides are thus alkyl and / or alkenyloligoglucosides. The index number p in the general formula V indicates the degree of oligomerization (DP), i.e. the distribution of mono- and oligoglycosides and means a number from 1 to 10. While p in a given compound must be an integer and here in particular have a value of p = 1 to 6 p value for a certain alkyloligoglycoside is an analytically determined calculated quantity, which is usually a fraction. Preference is given to using alkyl- and / or alkenyloligoglycosides having a mean degree of oligomerization of p from 1.1 to 3.0. Preferred for the application are those alkyl- and / or alkenyloligoglycosides whose degree of oligomerization is less than 1.7 and in particular has a value of from 1.2 to 1.4. The alkyl or alkenyl radical R ⁹ may be derived from primary alcohols having 4 to 11, more preferably 8 to 10, carbon atoms. Typical examples are butanol, caproalcohol, caprylalcohol, caprinal alcohol and undecyl alcohol as well as technical mixtures thereof, such as can be obtained, for example, in the hydrogenation of industrial fatty acid methyl esters or during the hydrogenation of aldehydes in Roelen oxosynthesis. Preferred alkyloligoglukozidy of chain length _C8-C10 (DP = 1 to 3) resulting from the division by the distillation of the technical C ₈ -C ₁₈ fatty alcohol and -kokosového may be contaminated with less than 6% by weight. _C12- alcohols as well as alkyl oligo-glucosides based on industrial C18 _{/ 11-} oxoalcohols (DP = 1 to 3). The alkyl or alkenyl radical R ⁹ may further be derived from primary alcohols having 12 to 22, more preferably 12 to 14, carbon atoms. Typical examples are lauryl alcohol, myristyl alcohol,

Also cetyl alcohol, palmooleyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, elaidyl alcohol, petrozelinyl alcohol, arachyl alcohol, gadoleyl alcohol, behenyl alcohol, erucyl alcohol, brassidyl alcohol, as well as technical mixtures thereof, can be obtained as described above. Preference is given to _C12 / _14- cocoalcohol-reinforced alkyl oligoglucosides having a DP of from 1 to 3. Preference is given to using glycosides in amounts of from 1.5 to 6, more preferably from 2 to 4% by weight. relative to the device.

-10d) Salts of fatty acids

As further surfactants, the compositions of the invention may contain fatty acid salts of formula VI,

R ¹⁰ CO-OX (VI) wherein R ¹⁰ CO is an acyl radical of 12 to 22 carbon atoms and X is an alkali metal. Typical examples are the sodium and / or potassium salts of lauric acid, myristic acid, palmitic acid, palmitoolic acid, stearic acid, isostearic acid, oleic acid, elaidic acid, petrozelinic acid, linoleic acid, linolenic acid, elaeostearic acid, arachic acid, gadoleic acid. , behenic acid and erucic acid, as well as their technical mixtures, such as those formed by pressure digestion of industrial fats and oils. Preference is given to the use of salts of technical coconut or tallow fatty acid. Since the formulations of the invention are strongly alkaline, it is possible to use fatty acids instead of salts which, when added to the mixture, are neutralized in situ. The compositions according to the invention in which particularly low foaming is desired preferably contain fatty acid salts as optional ingredients. Preference is given to the use of soaps in amounts of from 1.5 to 6, more preferably from 2 to 4% by weight. relative to the device.

Industrial usability

The bleaching compositions obtained using the polyelectrolytes of the invention generally have a non-aqueous proportion of from 5 to 35, and more preferably from 8 to 15 wt. and are suitable for the treatment of textile products such as yarns, fabric belts and especially textiles. Their use at low temperatures is common. j. in the cold wash area (approximately 15-25 ° C). The compositions are not only excellent in stain removal, but also reliably prevent metal traces from settling on the fibers and thus prevent yellowing. Although the actual use of the compositions is to wash stains, they are also well suited for other purposes where hypochlorite solutions are used, for example, for cleaning and disinfecting hard surfaces.

Other auxiliary substances and additives which may be used are, for example, other chlorine-stable surfactants or hydrotropes, such as alkyl sulfates, alkylsulfonates, alkylbenzenesulfonates, xylolsulfonates, sarcosinates, taurides, isothionates, sulfosuccinates, betaines, sugar ester, polyglycol ethers of fatty alcohols and polyglycol ethers of fatty alcohols . It is preferred that the sum of all surfactants is at most 10-15% by weight. the total amount of ingredients in the recipe. The compositions according to the invention may contain alkali metal compounds, in particular sodium hydroxide or potassium hydroxide, by means of which the pH of the formulation can be adjusted to an optimum value of 10 to 14, more preferably 12.5 to 13.5.

In addition, the compositions may contain chlorine-active fragrances, optical brighteners, dyes and pigments in amounts from 0.01 to 0.5% by weight in total. relative to the device. Known active chlorine-stable fragrances include, for example, monocyclic and bicyclic monoterpene alcohols as well as their esters with acetic or propionic acid (e.g., isoborneal, dihydroterpene oil, isobornyl octane, dihydroterpenylacetane). Other suitable fragrances are mentioned, for example, in EP-A1 0622451 (Procter & Gamble) and JP-A Sho 62/89800 (Raison). For example, the optical brighteners may be the potassium salt of 4,4'-bis- (1,2,3-triazolyl) - (2 -) - stilbine-2,2-sulfonic acid, which is distributed under the Phorwite® BHC 766 brand. colored pigments can be used among others green chlorophthalocyanines (Pigmosol® Green, Hostaphine® Green) or Solar Yellow BG 300 (Sandoz). The compositions are produced by mixing. Optionally, the product obtained for separating foreign particles and / or agglomerates can be decanted or filtered. The compositions have a viscosity greater than 100 mPas measured at 20 ° C in a Brookfield viscometer.

DETAILED DESCRIPTION OF THE INVENTION

To determine the bleaching effect, the soiled fabric was treated with various bleach solution solutions. The yellowing of the fabric was determined photometrically, with the starting value of the soiled fabric serving as a standard

-12 (100%). The measurements were carried out in a bath containing metal ions of 300 ppb Fe and 100 ppb Mn; the water hardness was 1000 ppm CaCl ₂ , the bicarbonate content was 0.013 wt. The ratio of bath (fabric: water) was 1:50, the treatment time was 30 minutes at 40 ° C. The results are summarized in Tables 1 and 2, the amount data being understood as% by weight.

Table 1

Bleaching effect - Examples according to the invention

composition 1 2 3 4 5 6 7 8 9 10 sodium hypochlorite 5.0 sodium hydroxide 0.5 adipic acid 0.3 - citric acid - 0.3 polyacrylic acid (M = 1000) 0.3 - - - - - - polyacrylic acid (M = 10,000) 0.3 - - - - - - polyacrylic acid (M = 100 000) - 0.3 - - - polymethacrylic acid (M = 50 000) - - - - 0.2 - - - - polymethacrylic acid (M = 500 000) • - - 0.2 - - acrylic / methacrylic acid copolymer (1: 1) (M = 15 000) 0.2 acrylic / methacrylic acid copolymer (1: 1) (M = 75 000) 0.2 acrylic / methacrylic acid copolymer (1: 1) (M = 150 000) 0.2 sodium silicate * - - - - - 0.1 0.1 0.1 0.1 0.1 sodium carbonate acid amine oxide ** - • - - 0.05 0.05 0.05 0.05 0.05 yellowing [% rel.] 89 89 88 86 82 79 77 77 75 73

*) Module 2.0 **) Sequion®

-13Table 1 - continued Bleaching effect

composition 1 2 3 4 5 6 7 8 9 10 sodium hypochlorite 5.0 sodium hydroxide 0.5 polymaleic anhydride (M = 5000) 0.3 maleic anhydride-acrylic acid copolymer (1: 1) (M = 25,000) 0.3 maleic anhydride-styrene copolymer (7: 3) (M = 12,000) 0.3 polyacrylamide (M = 20 000) - - - 0.3 - - - - - - polyacrylamide (Sepigel® 305) *** - - 0.3 - - - - poly - (N, N-bis-carboxymethylene-acrylamide (M = 10 000) 0.3 poly-3-acrylamido-3-methylpropanesulfonic acid (12,000) 0.3 3-acrylamido-3-methylbutyltrimethylammonium chloride (M = 5 000) 0.3 polyethyleneimine (M = 15,000) 0.3 - polypropyleneimine (M = 18,000) 0.3 sodium silicate * 0.1 sodium carbonate acid amine oxide ** 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 yellowing [% rel.] 79 78 80 74 70 77 78 79 81 80

***) polyacrylamide + Laureth-7 + isoparaffin (SEPPIC / FR)

-14Table 2

Bleaching Effect - Comparative Examples without Polyelectrolyte

composition V1 V2 V3 V4 V5 V6 V7 V8 V9 V10 sodium hypochlorite 5.0 sodium hydroxide 0.5 sodium silicate 0.1 0.2 0.3 0.2 0.2 0.2 0.2 0.2 0.2 0.2 sodium carbonate - - - 0.1 0.2 - - 0.1 0.2 0.2 acid amine oxide ** - - 0.1 0.2 0.1 0.1 0.2 yellowing [% rel.] 96 98 101 93 91 94 94 91 91 90

It is recognizable that the addition of polyelectrolytes to the alkaline hypochlorite solution results in a clear lightening of the fabric, which can be further improved by the addition of buffers. On the other hand, the addition of buffers as a separate stabilizer is sometimes disadvantageous compared to pure hypochlorite solution.

Claims (13)

PATENT CLAIMS Use of low molecular weight dicarboxylic acids as sequestering agents in the manufacture of aqueous bleaching compositions. 2. Use of polyelectrolytes to reduce the deposition of heavy metal ions on textile fibers during washing with aqueous bleaching compositions. Use according to claim 2, characterized in that polyelectrolytes selected from the group consisting of: (a) low-molecular-weight dicarboxylic acids; (b) low molecular weight polyhydric hydroxycarboxylic acids; c) mono- and copolymers of unsaturated monocarboxylic acids and their esters, (d) homo- and copolymers of unsaturated dicarboxylic acids and their derivatives; and / or e) homo- and copolymers of unsaturated monocarboxylic acid amides and derivatives thereof. Use according to claims 1 to 3, characterized in that the low molecular weight dicarboxylic acids have the formula I, R ¹⁰ OOC (CH ₂ ) _n COOR ² (I) wherein R ¹ and R ² are hydrogen, an alkali metal and / or an alkaline earth metal, ammonium, alkylammonium, alkanolammonium or glucammonium and n is a number from 0 to 64. Use according to claims 1 to 4, characterized in that the polyelectrolytes of group b) are citric acid and / or sodium citrate. -166. Use according to claims 1 to 5, characterized in that the polyelectrolytes of group c) are homo- and copolymers which can be derived from formula II, CH ₂ = CR ³ (CH ₂ ) _m COOR ⁴ (II) wherein R ³ represents hydrogen or a methyl group, R ⁴ represents hydrogen or a linear or branched hydrocarbon radical having 1 to 22 carbon atoms and m is a number from 0 to 10. Use according to claims 1 to 6, characterized in that the polyelectrolytes of group d) are homo- and copolymers of maleic anhydride. Use according to claims 1 to 7, characterized in that the polyelectrolytes of group e) are homo- and copolymers of polyacrylamide and / or polymethacrylamide. Use according to claims 1 to 8, characterized in that the polyelectrolytes are selected from the group consisting of poly- (N, N-bis-carboxymethylene-acrylamides), copolymers of fumaric acid and vinyl sulphonic acid, polymers of 3-acrylamido-3-methylpropanesulphonic acid, copolymers. acrylic acid and styrene sulfonic acid, copolymers of acrylic acid and 2-hydroxyethyl methacrylate monophosphate, homo- and copolymers of 3-acrylamido-3-methylbutyltrimethylammonium chloride; Use according to claims 1 to 9, characterized in that the polyelectrolytes have a molecular weight in the range from 300 to 5 000 000. Use according to claims 1 to 10, characterized in that the polyelectrolytes are used in amounts of from 0.01 to 5% by weight. based on an aqueous bleaching composition. Use according to claims 1 to 11, characterized in that the polyelectrolytes are used in hypochlorite-containing bleaching compositions. Use according to claims 1 to 12, characterized in that the polyelectrolytes are used together with buffers selected from the group consisting of alkali silicates, carbonates, phosphonates and / or alkaline earths. Use according to claims 1 to 13, characterized in that the polyelectrolytes are used together with chlorine-stable surfactants selected from the group consisting of alkyl ether sulfates, amine oxides, alkyl and / or alkenyloligoglycosides and / or fatty acid salts. Use according to one of Claims 1 to 14, characterized in that the polyelectrolytes are used together with chlorine-stable fragrances.