EP1692251B1 - Method for preventing or minimizing color deposits using polyesters - Google Patents

Abstract

A method for inhibiting or minimizing dye redeposition in decolorization of a dyed fabric containing cotton fibers involves contacting the fabric during the process with a redeposition inhibitor consisting of a polyester (I), obtained from (a) dicarboxylic acids, (b) 2-6C diols and (c) polyether alcohols containing 1 or 2 OH groups and at least 6 O atoms, were (a), (b) and (c) form more than 80 wt. % of the monomers incorporated in (I).

Description

The present invention relates to a method for preventing or minimizing color position on fabric during a decoloring process, especially during a "stone-wash" process. The fabric is preferably indigo-dyed cotton or cotton-containing fabrics. The anti-color redeposition agent used is a polyester, preferably a terephthalic acid polyester-polyether polymer.

In order to give the indigo-dyed denim fabrics the typical "wash-out look" or "used look", jeans fabrics are subjected to a so-called "stone-wash" process ,

At the end of the 1970s, the pumice stone was discovered to accelerate the aging process of the indigo-dyed parts. The "stone-wash look" is made possible by the fact that the dye is essentially only applied to the outer regions of the fibers. This is characteristic of an indigo dye. This is referred to as a so-called coat color, in which the color does not penetrate into the yarn, but it envelops like a coat and the core of the yarn or the fibers is not discolored.

In a treatment of indigo-dyed fabric in a washing machine, the fabric is treated with pumice blocks until the outermost layer of the yarn is teilabgetragen and the uncolored interior emerges (Verlag Textilveredlung AG, Journal: Textile Finishing, 34 (11-12), 26 -31 (1999); 35 (1-2), 23-27 (2000), 35 (3-4), 27-30 (2000); Title: Jeans - The Blue Phenomenon).

As a rule, about 1 to 2 times the amount of tissue weight of pumice stones is used for this purpose. How much pumice is used for the aging process of the tissue in each case, depends on the desired effect.

The classic stone-wash process has some economic and ecological disadvantages. Both the denim fabric and the washing machine itself are subjected to very heavy mechanical stress during the process. This leads, inter alia, to high wear of the built-in drum washing machines sheets. Due to the abrasion of the stones, fine particles are generated. The consequence is the absolutely necessary removal of these fine particles from the tissue by repeated washing, which results in larger amounts of process water to be disposed of. Furthermore, treatment with pumice stones causes large amounts of sludge in connection with fiber residues and indigo pigment.

Since the eighties, a new technique has been established that is based on the use of special enzymes. For the superficial degradation of the cellulose, instead of abrasion by the pumice, enzymes are used. The enzyme used here is usually a cellulase. The cellulase is temporarily bound to the cellulose by an anchor and cleaves it to its 1,4-betaglucosidic linkage. As a result, the surface of the cotton fiber on which the indigo dye is located, partially detached. As a result, underneath, not colored and thus white areas of the cotton fiber come to light. In this way, the use of the cellulases achieves an optical effect, which corresponds to the use of pumice.

The cellulases used in the enzymatic stone-wash process can be divided into two groups: acidic and neutral cellulases. The terms "acidic" and "neutral" are used to describe the pH at which the enzyme develops its optimum performance. For acid cellulases, this is the range of about 4 to 6, while neutral cellulases show their optimum performance at pH values of about 6 to 8. A major difference is the higher abrasion that allows acidic cellulases compared to neutral ones. With acidic cellulases, the same abrasion properties can be set when using 10 to 20% of the amount of neutral cellulase. As a consequence, acid cellulases allow shorter treatment times and are also significantly cheaper, which leads to an overall economic advantage. Disadvantages, however, are the so-called "backstaining" (color printing position).

Under color printing position refers to a back discoloration or Rückanschmutzung including the cotton with peeled dye or dye on fiber remains. These deposits can be observed at various points, such as inside pockets, labels, seams, zippers, but also in particular on the inner and outer surface of the denim. Backstaining creates an undesirable low-contrast appearance of the product.

The phenomenon of color edging is much more pronounced in stone-washing than in classical household laundry, due to the significantly higher color concentration in the washing process.

Various theories have been published in the scientific literature that try to explain this phenomenon: One hypothesis is that the cellulose is enzymatically degraded to glucose units, which in turn are capable of producing indigo both in the solution and on the fiber partially reduce. The reduced form has a lower affinity for the cellulosic fiber and is thereby intended to effect enhanced deposition on the pocket liners. Another theory assumes that the indigo has a strong affinity for cellulase, which in turn is bound to the cellulose fiber via a so-called CBD (= cellulose binding domain).

It can be assumed that the color printing position is a function of the cellulase mixture used, the dye, the type of surfactant used, the surfactant concentration and the pH.

• Die WO 01/92453 beschreibt ein enzymatisches Verfahren bei dem Farbredeposition minimiert wird durch Zugabe lipolytischer Enzyme, bevorzugt Cutinase. In der WO 94/29426 wird zu diesem Zweck saure Cellulase zusammen mit einer speziellen Protease eingesetzt. Aus der DE 19606619 ist bekannt, saure Cellulasen in Kombination mit Fettalkoholpolyglykolethern und anorganischen und/oder organischen Puffersalzen einzusetzen.

In the prior art, some methods have been described to reduce the color edging position:

• The WO 01/92453 describes an enzymatic process in which color press position is minimized by adding lipolytic enzymes, preferably cutinase. In the WO 94/29426 For this purpose, acid cellulase is used together with a special protease. From the DE 19606619 It is known to use acidic cellulases in combination with fatty alcohol polyglycol ethers and inorganic and / or organic buffer salts.

Furthermore, the combined use of nonionic fatty alcohol ethoxylates with anionic alkanesulfonate to achieve an anti-redepositon effect is described. In particular, anionic surfactants, however, lead to a negative interaction with the cellulase, such that their abrasiveness is reduced.

The WO 01/57173 describes an enzymatic 2-component system by means of which it is possible to produce a good stone-wash effect on dyed cotton or cotton-containing fabrics with a simultaneously very low Backstaining. The 2-component system contains, in addition to a cellulase component, special aqueous polymer dispersions whose solid particles are styrene / (meth) acrylic acid ester copolymers which have been grafted onto starch as the graft base.

The WO 95/35363 describes a method for producing a stone-wash effect by using acidic cellulases in the presence of color anti redeposition agents selected from the group of natural and synthetic, inorganic silicates, polyalkylene oxides, acrylic acid polymers and natural and synthetic or semisynthetic polysaccharides.

Many of the color transfer inhibitors described in the prior art, such as polyvinylpyrollidones, polyvinylpyridine N-oxides, etc., are effective systems for reducing the redeposition of direct dyes to cotton. Nevertheless, these compounds are not effective enough when it comes to backstaining In particular, to prevent indigo, which may be - without wishing to be bound by theory - may be due to the extreme hydrophobicity of this dye.

From the WO 99/67350 Polyesters are already preparable by reacting polymeric waste terephthalates, such as polyethylene terephthalate, polybutylene terephthalate or poly (cyclohexanedimethanol) terephthalate, glycols and oxyalkylated polyols having at least 3 hydroxyl groups, which are used in dyeing and Entfärbeprozessen to prevent the color printing position. The actually disclosed polyesters are further prepared using trimellitic acid and / or isophthalic acid or their derivatives.

The object of the present invention is to provide a means which effectively prevents inking deposition on textile fabric during a decoloring process, ie during a stone-wash process and / or biostoning process.

The agent should act as an anti-redeposition agent for the released dye, in particular indigo, or the dye-coated particles, such that it not only compared to the pure denim, but also with respect to typical accessories of denim or jeans such as pocket lining, stitching , Labels and zippers, which are often not made of cotton.

From the WO 99/67350 For example, polyesters formed from terephthalic acid units and glycols and / or polyether diols are known which are used in dyeing and decolorization processes to prevent color printing. In essence, the subject matter of WO 99/67350 Polyethylene terephthalates obtained from waste polyethylene terephthalates by reaction with glycols and oxyalkylated polyols as part of an ester cleavage or transesterification reaction. In the transesterification, isophthalic acid and optionally trimellitic acid should be present. The JP-A-2002- 142760 -A teaches polyester from terephthalic acid oligoalkylene glycol units with up to 4 ethylene glycol units in total. The US-A-5,486,297 relates to a finishing agent which prevents the fading of the color strength of textiles

The object is achieved by a. A process according to claim 1, wherein the monomers (A), (B) and (C) preferably constitute greater than 90% by weight, in particular greater than 95% by weight, of the incorporated monomers, and the use according to claim 13.

Preferred embodiments are subject of the dependent claims or described below.

The use of the anti-redeposition agents described in the method according to the invention leads to a very low backstaining with a simultaneously excellent stone-wash effect.

The object is achieved according to the invention with polymers as they are known as soil release polymers (soil release polymers). In the present case, these are preferably amphiphilic, preferably nonionic polyester-containing polyether monomer sequences.

Polyetherols are used to prepare the polyether monomer sequences. Polyetherols in the context of the invention are compounds having one or two hydroxyl groups containing at least 6 oxygen atoms, preferably at least 10 oxygen atoms and in particular more than 16 oxygen atoms.

Diols in the context of the invention are compounds which have 2 hydroxyl groups and at most one, preferably no ether groups.

Compounds within the meaning of the main claim of the present invention are organic compounds which, in addition to carbon, hydrogen and oxygen after reaction, i. Incorporation into the polymer, i.d.R. have no further atoms. This means, for example, that the dicarboxylic acid compounds, after incorporation into the polyester, may carry not only carboxyl groups, but also carbonyl or hydroxyl groups, but e.g. have no sulfonyl or halogen groups,

The dicarboxylic acid compound (A) are terephthalic acid and optionally aliphatic and / or aromatic dicarboxylic acids and derivatives thereof, ie, for example, their monoesters, diesters, anhydrides or mixtures. The dicarboxylic acid compounds have - based on the dicarboxylic acid or dicarboxylic acid group - preferably 3 to 40 carbon atoms. In particular, aromatic dicarboxylic acid compounds may be isophthalic acid, phthalic acid, their mono- and dialkyl esters with C _{1 to} C ₅ alcohols, such as dimethyl terephthalate, mixtures of these Connections are possible. Examples of aliphatic dicarboxylic acid compounds are malonic acid, succinic acid, fumaric acid, maleic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid dialkyl esters. Isophthalic acid and phthalic acid, and their dimethyl, diethyl, dipropyl and dibutyl esters are particularly preferably used.

Are used as the dicarboxylic acid in the process according to the invention terephthalic acid, to greater than 90 mol%, preferably greater than 95 mol%, based on the di- or tricarboxylic acid compounds used. In addition, other dicarboxylic acid compounds may also be used.

Aromatic dicarboxylic acids in addition to terephthalic acid, in particular isophthalic acid, phthalic acid, their mono- and dialkyl esters with C1 to C5 alcohols, such as. Dimethyl terephthalate, of course, mixtures of these components are possible. Examples of aliphatic dicarboxylic acid equivalents are malonic acid, succinic acid, fumaric acid, maleic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid dialkyl esters.

Particularly preferred are terephthalic acid and phthalic acid and their dimethyl, diethyl, dipropyl and dibutyl esters.

In principle, it is also possible to use tricarboxylic acid compounds, as a result of which highly branched polymer structures become accessible. Suitable for this purpose are e.g. Trimellitic acid or its derivatives such as anhydrides and esters. However, their use is usually to be avoided.

The polyol compounds (D) preferably have 3 to 12 carbon atoms. Examples of the polyol compounds having at least 3 OH groups are: pentaerythritol, trimethylolethane, trimethylolpropane, 1,2,3-hexanetriol, sorbitol, mannitol, mono-, di- and triglycerol, 1,2,3- Butanetriol, 1,2,4-butanetriol. Preference is given to the use of glycerol.

As a particularly significant component of the polymers mentioned are the polyether oleczu call, which represent preferably to more than 30 wt.%, A major proportion of the polymer. Examples of these are polypropylene glycol, polybutylene glycol and addition products of ethylene oxide, propylene oxide, butylene oxide or their mixtures of aliphatic alcohols such as methanol. Ethanol, propanol, butanol or long-chain fatty alcohols. The methylene glycols can be used with weight average molecular weights of 3000 to 8000 g / mol. Polyethylene glycol monomethyl ethers having molecular weights of 2,000 to 5,000 g / mol may be preferably used.

As the diol compound (B), in addition to the ethylene glycol, 1,2- or 1,3-propylene glycol, neopentyl glycol, 1,2-butylene glycol, 3-methoxy-1,2-propylene glycol and their dimers and trimers can be used. The diol compound (B) preferably has 2 to 6 carbon atoms. In principle, mixtures of different diols are possible. Preference is given to the use of ethylene glycol and propylene glycol.

In principle, it is also possible to modify the polymers anionically. This can e.g. by condensation of anionic monomers, e.g. Sulfophthaloyl, Sulfoisophthaloyl- and Sulfoterephthaloyl- groups which are used in the form of their salts, in particular as alkali metal or ammonium salts. In general, aliphatic anionic monomers derived from sulfonated aliphatic diesters, e.g. Derive maleic acid, adipic acid, sebacic acid, etc.

• a.) Sulfoaroylgruppen,
• b.) Gruppen mit der Formel MO₃-S-(O)_u-(CH₂)_p-(RO)_w-, in der M für ein Metallatom und R für Ethylen oder Mischungen von Ethylen und Propylen, u für 0 oder 1, p für 0 oder 1 und w für eine Zahl von 1 bis 100 stehen,
• c.) Poly(oxyethylen)monoalkylether-Gruppen, in denen die Alkylgruppe 1 bis 24 C-Atome enthält und die Polyoxyethylengruppe aus, 2 bis 200 Oxyethyleneinheiten besteht,
• d.) Acyl- und Arylgruppen mit 4 bis 40 Kohlenstoffatomen,
• e.) Hydroxyacyl- und Hydroxyaroylgruppen mit 2 bis 25 Kohlenstoffatomen,
• f.) Poly(oxyalkylen)monoalkylphenolether, in denen die Alkylgruppe 6 bis 18 Kohlenstoffatome enthält und die Polyoxyalkylengruppe aus 0 bis 80 Oxyalkyleneinheiten besteht

sowie auch Mischungen davon.The polyesters used in the process according to the invention may also have an end group closure. Suitable end groups are:

• a.) sulfoaroyl groups,
• b.) groups of the formula MO ₃ -S- (O) _u - (CH ₂ ) _p - (RO) _w -, in which M is a metal atom and R is ethylene or mixtures of ethylene and propylene, u is 0 or 1, p is 0 or 1 and w is a number from 1 to 100,
• c.) poly (oxyethylene) monoalkyl ether groups in which the alkyl group contains 1 to 24 C atoms and the polyoxyethylene group consists of 2 to 200 oxyethylene units,
• d.) acyl and aryl groups having 4 to 40 carbon atoms,
• e.) hydroxyacyl and hydroxyaryl groups having 2 to 25 carbon atoms,
• f.) poly (oxyalkylene) monoalkylphenol ethers in which the alkyl group contains 6 to 18 carbon atoms and the polyoxyalkylene group consists of 0 to 80 oxyalkylene units

as well as mixtures thereof.

Particularly preferred are nonionic PET (polyethylene terephthalate) -PET (polyoxyethylene terephthalate) polyesters. These can be obtained by polycondensation of terephthalic acid or terephthalic acid esters with monoethylene glycol and polyethylene glycol. These are polyethylene glycols having molecular weights of 2,000 to 8,000 g / mol. Preferably, the recovered PET-POET copolymers are solid at room temperature and have weight average molecular weights of 5,000 to 40,000 g / mol.

Further preferred is the use at room temperature of liquid polyester-polyether copolymers represented by the formula

X- (OCH ₂ -CH ₂ ) _n - [- (OOC-R ¹ -COO-R ² ) _u -] - OOC-R ¹ -COO- (CH ₂ -CH ₂ O) _n -X

wherein each R ¹ radical is a 1,4-phenylene radical, optionally mono- or di-C ¹ -C ³ -alkyl-substituted; the R ² radicals are essentially ethylene radicals, 1,2-propylene radicals or mixtures thereof; each X is independently hydrogen, a C1 to C12 hydrocarbon radical, especially ethyl or methyl; each n is independently from 7 to 115 and u is from 3 to 10.

The synthesis of the polymers used according to the invention can be carried out in the form of a direct reaction of all monomer building blocks in one step, so that statistically distributed polymers (so-called "random" structures) are obtained. Another mode of preparation is a multi-step synthesis e.g. in such a way that a precondensation of different components takes place.

Basically, temperatures of about 80 to 350 ° C and pressures of normal pressure to <1 mbar are set. Preferably, the condensation is carried out in the temperature range of 150 to 280 ° C in the presence of the usual polycondensation and transesterification catalysts. The polymers obtained can be adjusted to different molecular weights. These are preferably between 1,000 and 40,000 g / mol.

Suitable catalysts are known from the literature compounds. If the free dicarboxylic acids or anhydrides are used as the component, p-toluenesulfonic acid is the preferred catalyst. If dicarboxylic acid dialkyl ester is used as the component, the usual transesterification catalysts are used, such as, for example, mixtures of calcium acetate and antimony oxide, organic and inorganic tin and zinc compounds (eg stannanes, zinc acetate or the TEGO® catalysts of Degussa) or tetraalkoxytitanates, such as titanium tetraisobutanolate or tetraisopropoxide.

The condensation can be carried out in the presence of antioxidants, e.g. substituted phenols such as 2,5-di-tert-butylphenol, 2-methylcyclohexyl-4,6-dimethylphenol, phosphorous acid or other antioxidants commonly used therefor. These compounds prevent discoloration of the polyesters by oxidation during condensation.

As far as the color of the polyester according to the invention is still not satisfactory, they can be subjected to a post-treatment. A common aftertreatment is, for example, a bleaching with hydrogen peroxide, which leads to a clear color lightening.

The polymers used in the process according to the invention can be obtained both in solid and in pasty to liquid form. In principle, there are various possibilities for introducing the polymers into the corresponding formulations. For powdered i. solid stone-wash formulations, the additives are also preferred in solid form. It is possible, depending on the morphology, to use the polymers both as 100% form e.g. milled form or in supported form i. by applying the polymer to a solid support by means of the granulation methods described in the prior art.

In principle, these compounds can also be used in the form of a matrix. Under matrix here is the blend of amphiphilic polyester-polyether copolymers with, for example, nonionic surfactants, such as alcohol ethoxylates, alcohol propoxylates, mixed alcohol alkoxylates, alkyl polyglucosides, glucose amides, polyethylene glycols, polypropylene glycols, mixed polyalkylene glycols, solvents such as isopropanol, propylene glycol, glycol ethers, water.

By blending or packaging with other products, e.g. even better flowable low viscosity products can be obtained.

The polyester-polyether copolymers may also be supported on support materials, e.g. Zeolites, phosphates, citrates, sodium sulphate, pumice or pumice equivalents such as perlites and thereby e.g. be converted into free-flowing powdery compounds. Such compounds can be advantageously incorporated in powdered stone wash formulations.

The antiredepositol agents used in the process according to the invention are preferably used in amounts of from 0.1 to 20% by weight, based on the Stone Wash formulation (excluding abrasives).

In principle, it is possible to incorporate the anti-color redeposition agents in the formulation. On the other hand, it is also possible to introduce them later in the direct application (Stone-Wash fleet).

Most formulations are based on a combination of mechanical treatment and enzyme treatment (stone-washing and biostoning). Instead of pumice sintered perlites are often used, which lead due to their hardness to less abrasion during the process. In addition, they are smaller than pumice stones, have a larger surface area, which makes it possible to rinse the stones with the wash liquor.

The central building block of the enzymatic formulations for producing a stone-wash effect is one or more cellulases. Essentially, two groups of cellulases are used: acid and neutral.

In addition to the antiredeposition agents according to the invention, these formulations contain further constituents.

For example, a buffer system which has the task of keeping the pH constant within certain limits in order to ensure optimal performance of the enzyme system. The buffering of the cellulase bath is very important, since alkalinity is often introduced by the tissue in particular.

Another essential ingredient of these formulations are surfactants. Their task is u.a. to accomplish rapid wetting of the cellulosic fiber such that the cellulase can attack the fiber as quickly as possible. Further functions of the surfactants are the removal of excess sizing agent, the suspension of the indigo dye and the emulsification of oil and fat components. In addition, they continue to serve as dispersants and Lauffaltenverhinderer within this application.

Nonionic surfactants such as the fatty alcohol alkoxylates described in the prior art, castor oil ethoxylates etc. are preferred. The reason for the preferred use of nonionic surfactants lies in their good wetting of the fibers with at the same time little influence on the cellulase activity. Anionic surfactants can sometimes have negative effects on the enzymes, such that their activity is reduced or incompatibilities occur. The proportion of surfactant within the formulations is preferably in the range from 5 to 25% by weight (excluding abrasives).

Optionally, Stone-Wash formulations may also contain other ingredients, e.g. Enzyme activators, solubilizers, solvents, antioxidants, builders or sequestering agents.

Examples of typical solvents are: ethylene glycol, propylene glycol and their oligomers / polymers, terpenes, hydrocarbons. Examples of enzyme activators are: proteins, salts of monosaccharides, e.g. Mannose and xylose. Typical solubilizers are: short-chain alcohols, benzenesulfonate salts, propylene glycol, benzoates, etc. Builders or sequestrants often used are: organic phosphates, phosphonates, polyacrylic acids, polyvinyl alcohols, polyvinylpyrollidones, borates, citrates.

Both powder formulations and liquid formulations are suitable. The process of producing denim or denim consists essentially of three main steps: desizing, abrasion (stoning / biostoning) and bleaching.

In the first step of defecating, the sizing agent, which is usually starch, is removed. In earlier times, this step was accomplished by alkaline scrubbing at higher temperatures. Today, one also prefers an enzymatic process based on the use of specific amylases or combinations of amylases and lipases. These break down the starch polymers into short, water-soluble fragments that can be washed out. The background of this step is the creation of soft denim surfaces, prevention of banding and preparation of the fabric for the subsequent step of abrasion. In addition to the enzymes, surfactants are also used in this step.

In principle, one or more rinsing steps can take place before the next treatment step.

The abrasion step is the described stone-washing or biostoning or combinations of stone-washing and biostoning. Through the use of special cellulase or cellulase mixtures cellulose fragments are removed from the surface, creating the classic stone-wash look.

After achieving the required abrasion, the cellulases must be deactivated to stop further degradation of the tissue. This is done in a subsequent washing process, at alkaline pH values and higher temperatures at which the enzyme denatures. Finally, the tissue i.d.R. under standard conditions bleached with the bleaching agents described in the prior art, e.g. Hypochlorite.

The antiredeposition agents described in the method according to the invention are also distinguished, inter alia, by their affinities for hydrophobic surfaces such as, for example, polyester, polyamide or their blended fabrics with cotton. Since the accessories of jeans such as pocket lining, zippers, labels, seams, etc. are often made of these materials, it is recommended additives of the invention not only in the actual stone-wash process but before, ie in the desizing of the fiber. Here, these accessories receive an efficient surface impregnation, which essentially means that the indigo released in the stone-wash process is less attracted to these surfaces.

Examples:

The polyesters of the example 1,2,4 are not covered by the claims.

Example 1:

A total of 640 g (1.45 mol) of polyethylene glycol monomethyl ether having a weight-average molecular weight of about 440 g / mol (MARLIPAL 1) were introduced into a 2 l multi-necked flask with glass stirrer, heating bath, inert gas inlet, distillation head, packed column, distillation bridge, vacuum distributor, distillation flask, cold trap and internal thermometer / 12 from Sasol Germany GmbH), 388 g (2.0 mol) of dimethyl terephthalate, 110.5 g (1.2 mol) of glycerol, 145.8 g (1.4 mol) of neopentyl glycol, 1.0 g of 2,6- Di-tert-butyl-p-cresol (Ionol from Shell) and 1 ml of tetraisopropyl orthotitanate submitted under inert gas.

The reaction mixture was slowly heated to temperatures of 150 to 220 ° C and collected the methanol formed. After most of the theoretically expected amount of methanol was collected, the reaction mixture was cooled, the column removed, vacuum applied and the mixture heated again up to a maximum of 230 ° C. The unreacted in the reaction diol / polyol mixture was collected as distillate.

After the polyester had reached a hydroxyl value of about 90 mg KOH / g substance, the reaction was stopped. The product was a yellow, low viscosity oil.

Example 2:

In analogy to Example 1, a total of 883 g (2.0 mol) of polyethylene glycol monomethyl ether having a weight-average molecular weight of about 440 g / mol (MARLIPAL 1/12 of Sasol Germany GmbH), 534 g (2.75 mol) of dimethyl terephthalate, 227.9 g (2.5 mol) of glycerol, 68.3 g (1.1 mol) of monoethylene glycol, 1.0 g of 2,6-di-tert-butyl-p-cresol (Ionol from Shell) and 1 ml of tetraisopropyl orthotitanate reacted.

After the polyester had reached a hydroxyl value of 112 mg KOH / g substance, the reaction was stopped. The product was a yellow, low viscosity oil.

Example 3:

In analogy to Example 1, a total of 4947 g (1.65 mol) of polyethylene glycol having a weight-average molecular weight of about 3,000 g / mol (Lipoxol 3000 from Sasol Germany GmbH), 1,056 g (5.44 mol) of dimethyl terephthalate, 580 g (9 , 3 mol) of monoethylene glycol, 4.0 g of 2,6-di-tert-butyl-p-cresol (Ionol from Shell) and 4 ml of tetraisopropyl orthotitanate reacted.

After the polyester reached a hydroxyl value of 30 mg KOH / gm of substance, the reaction was stopped. The product was present as a yellow solid resin.

Example 4:

In analogy to Example 1, a total of 1106 g (1.47 mol) of polyethylene glycol monomethyl ether having a weight-average molecular weight of about 750 g / mol (NONIDAC M-750 from Sasol Italy), 229 g (1.18 mol) of dimethyl terephthalate, 179 g ( 2.36 moles) of 1,2-propylene glycol, 1.3 g of 2,6-di-tert-butyl-p-cresol (Ionol from Shell) and 1.3 ml of tetraisopropyl orthotitanate reacted.

After the polyester reached a hydroxyl value of 15 mg KOH / gm of substance, the reaction was stopped. The product was a yellow, low viscosity oil.

Claims (15)

1. A method of preventing or minimizing dye redeposition onto textile fabrics during a stonewashing and/or a biostoning process applied to indigo-dyed cotton fabrics by contacting the dyed fabric comprising cotton fibers with a dye redeposition inhibitor during the dye removal process, characterized in that the dye redeposition inhibitor is a polyester, which is obtainable by reacting at least the following monomers during an esterification reaction:

   (A) one or more dicarboxylic acid compounds, wherein terephthalic acid makes up more than 90 mole% of the dicarboxylic acid compounds employed,

   (B) one or more diol compounds having from 2 to 6 carbon atoms, wherein the ethylene glycol makes up more than 90 mole% of the diol compounds employed, and

   (C) polyetherols with one or two hydroxy groups having at least 6 oxygen atoms, wherein polyethylene glycol having a molecular weight from 2000 to 8000 g/mol makes up more than 90 wt.% of the polyetherols employed, and

   the monomers (A), (B) and (C) result in more than 80 wt.% of the incorporated monomers.
2. The method according to claim 1, characterized in that the monomers (A), (B), and (C) make up more than 90 wt.% of the incorporated monomers, particularly more than 95 wt.%.
3. The method according to any one of the proceeding claims characterized in that the polyesters are furthermore obtainable by using
   (D) one or more polyol compounds with at least 3 OH groups having from 3 to 12 carbon atoms, especially glycerol.
4. The method according to any one of the proceeding claims characterized in that the dicarboxylic acid compounds (A) comprise terephthalic acid, isophthalic acid, phthalic acid, and their derivatives.
5. The method according to any one of the proceeding claims characterized in that independently of one another

   (a) no tricarboxylic acid compounds and

   (b) no isophthalic acid or its derivatives

   are employed.
6. The method according to any one of the proceeding claims characterized in that the diol compound (B) is ethylene glycol and/or propylene glycol.
7. The method according to any one of the proceeding claims characterized in that the polyester is anionically modified by incorporation of anionic monomers and/or is capped with terminal groups.
8. The method according to any one of the proceeding claims characterized in that the polyetherols (C) are alkylene oxide addition products of ethylene oxide, propylene oxide, butylene oxide or their mixtures to aliphatic C1 to C 18, preferably C 1 to C6, alcohols and/or water.
9. The method according to any one of the proceeding claims characterized in that for the removal of dye abrasive stones and/or enzymes, especially at least cellulases, are put into contact with the fabric in order to achieve a stonewashed look.
10. The method according to any one of the proceeding claims characterized in that the dye redeposition inhibitor is put into contact with the fabric both during the stonewashing step and the preceding desizing step.
11. The method according to any one of the proceeding claims characterized in that the polyetherols (C) have from 16 to 180 C2 to C4 alkylene oxide units:
12. The method according to claim 1 and/or claim 2 characterized in that the polyester is not made utilizing polyols having at least 3 OH groups.
13. Use of a dye redeposition inhibitor for preventing or minimizing dye redeposition onto textile fabrics during a stonewashing and/or a biostoning process applied to indigo-dyed cotton fabrics by contacting the dyed fabric comprising cotton fibers with the dye redeposition inhibitor during the dye removal process, characterized in that the dye redeposition inhibitor are polyester composed according to the formula
    
            X-(OCH₂-CH₂)_n-[-(OOC-R¹-COO-R²)_u-]-OOC-R¹-COO-(CH₂-CH₂O)_n-X,
    
    wherein each R¹ residue is a 1,4-phenylene residue, optionally substituted for mono- or di-C1-C3 alkyl; the R² residues are essentially ethylene residues, 1,2-propylene residues, or mixtures thereof; each X represents independently of one another hydrogen, a C1 1 to C12 hydrocarbon residue, especially ethyl or methyl; each n is a number from 7 to 115, and u is a number from 3 to 10.
14. The use according to claim 13 characterized in that the polyester or polyester blend is liquid at room temperature.
15. The use according to claim 13 characterized in that the polyesters have molecular weights of less than 5000 g/mole.