WO2018037039A1

WO2018037039A1 - Process for the coating of textiles

Info

Publication number: WO2018037039A1
Application number: PCT/EP2017/071218
Authority: WO
Inventors: Rolf Irnich; Xuehui Zhao; Linling YAO; Xutian LIANG
Original assignee: Covestro Deutschland Ag; Covestro Polymers (China) Co. Ltd.
Priority date: 2016-08-24
Filing date: 2017-08-23
Publication date: 2018-03-01
Also published as: KR20190039717A; JP2019526714A; CN107780230A; TW201840927A; EP3504372A1

Abstract

The present invention relates to a process for coating a textile and the obtained coated textile. The process comprises the following steps: a) bringing the textile into contact with component A) which comprises a water-insoluble salt, a water-soluble thickener and water; and b) bringing the textile contacted with component A) into contact with component B) which comprises an aqueous polymer dispersion and an acid that is able to react with the water-insoluble salt in component A), to obtain a coated textile. The process provided in the present invention does not employ organic solvents, while enables the textile obtained by coating having good hand feeling, such as softness.

Description

Process for the Coating of Textiles

Technical Field

The present invention relates to a process for coating a textile and the obtained coated textile.

Background Art

Textiles after being coated can be used for the production of synthetic leather. Synthetic leathers are often employed as shoe upper materials, for articles of clothing or in furniture decorations. The process for coating textiles usually uses a polyurethane solution dissolved in an organic solvent, such as DMF. One of the common processes for coating textiles is coagulation process, comprising the steps of: initially impregnating the textiles in a polyurethane-containing solution, and then passing the textiles through DMF/water baths for multiple times, where the proportion of water in each DMF/water bath is increased stepwise. Coated textiles obtained using coagulation have good breathing activity and a soft hand feeling, and are suitable for being used as high-quality synthetic leathers. However, the toxicity of the organic solvents during the coating process would harm the health of the operators. To reduce the health harm caused by the organic solvents on the operators, factories need to employ additional protective measures, and thus the production cost increases. In addition, coagulation process would produce a large amount of azeotrope of DMF and water, which requires subsequent treatments.

Processes for coating textiles without using organic solvents have been developed in this industry. US2004/121113A1 discloses a process for the production of synthetic leathers: impregnating a non- woven textile or woven textile with a dispersion comprising a nonionic polyurethane and an external stabilizing surfactant; exposing the impregnated textile to water containing a coagulant for a coagulation time sufficient to coagulate the dispersion. The coagulant is a neutral salt of multi-valent cation which can be dissolved in water and can coagulate the aqueous polyurethane dispersion; it can also react with additives to generate water insoluble salt of an organic acid on the surface of the textile, thus imparting the textile with good water resistance.

CN103998679A discloses a process for coating a textile, comprising: initially impregnating the textile with a water dispersion comprising a water-soluble organic onium salt and a modified cellulose; and then impregnating the textile with a water dispersion comprising polyurethane; finally, depositing the water dispersion of polyurethane on the surface of the textile.

CN103003486A and CN103987891A disclose a process for coating a textile, comprising: initially impregnating the textile with a water dispersion comprising a water-soluble inorganic salt, such as calcium nitrate, magnesium nitrate, calcium chloride or magnesium chloride and a modified cellulose; and then impregnating the textile with a water dispersion comprising a polymer of polyurethane, polyacrylate or polybutadiene; finally, depositing the water dispersion of polyurethane on the textile.

In the above process for coating a textile, when the organic onium salt or inorganic salt soluble in water is in contact with the water dispersion of polyurethane, polyacrylate or polybutadiene, the metal cations released from the organic onium salt or inorganic salt soluble in water and the water dispersion of polyurethane, polyacrylate or polybutadiene deposit rapidly on the surface of the textiles and in the gaps of the textile fibers, thus shortening the coating operable time. Moreover, deposits in the gaps of the textile fibers cannot be removed by the subsequent washing step, thus making the coated textiles have a hard hand feeling, which is harmful for the application of the textiles, in particular in the synthetic leather industry.

To address the above problem, it is desirable in the industry for a process for coating a textile that does not employ organic solvents, such as DMF, while enables the coated textile having good properties, such as a soft hand feeling.

Summary

The object of the invention is to provide a process for coating a textile and a coated textile.

In an embodiment according to the invention, the process for coating a textile comprises the steps of: a) bringing the textile into contact with component A) which comprises a water-insoluble salt, a water-soluble thickener and water; and b) bringing the textile contacted with component A) into contact with component B) which comprises an aqueous polymer dispersion and an acid that is able to react with the water-insoluble salt in component A), to obtain a coated textile.

Preferably, the process is carried out in the absence of organic solvents.

In an embodiment according to the invention, the coated textile provided by the invention is obtained by conducting the process for coating a textile provided by the invention.

Preferably, the coated textile is free of water-insoluble salt. The coated textile may be synthetic leather. The textile may be a woven textile, knitted textile or nonwoven based on natural and/or synthetic fibers, preferably a nonwoven, such as staple fiber nonwoven or microfiber nonwoven.

The textile may be comprised of polyester fibers, nylon fibers, cotton fibers, polyester/cotton blended fibers, wool fibers, ramie fibers, spandex fibers, glass fibers, thermoplastic polyurethane fibers or thermoplastic olefin fibers, or the like.

The textile may have a web construction, a woven construction or a nonwoven construction.

The process for coating a textile provided by the invention enables excluding the use of organic solvents, which is advantageous for the health of operators and does not need additional steps for the separation of organic solvents; makes the operable period for coating a textile longer; and results in a good hand feeling of the obtained coated textile, such as softness, which is unique for the coated textile obtained by the coating process using organic solvents.

Specific Description

The present invention provides a process for coating a textile, comprising the steps of: a) bringing the textile into contact with component A) which comprises a water-insoluble salt, a water-soluble thickener and water; and b) bringing the textile contacted with component A) into contact with component B) which comprises an aqueous polymer dispersion and an acid that is able to react with the water-insoluble salt in component A), to obtain a coated textile. The present invention also provides the coated textile obtained by conducting this process for coating a textile.

The term "contact" should generally be understood as dipping or coating. The dipping may be either partial or complete dipping, preferably complete dipping. The coating can be conducted by means of, such as, a hand coater, printing or spraying.

The term "aqueous polyurethane dispersion" may further encompass aqueous polyurethane-polyurea dispersion.

The term "water-insoluble salt" should generally be understood as a salt that is completely insoluble in water, or a salt that has a very small solubility in water.

Step a)

The textile may be a woven textile, knitted textile or nonwoven based on natural and/or synthetic fibers, preferably a nonwoven, such as staple fiber nonwoven or microfiber nonwoven. The textile may be comprised of polyester fibers, nylon fibers, cotton fibers, polyester/cotton blended fibers, wool fibers, ramie fibers, spandex fibers, glass fibers, thermoplastic polyurethane fibers or thermoplastic olefin fibers, or the like.

Component A)

The amount of the water-insoluble salt is 0.5 to 50% by weight, preferably 0.5 to 25% by weight, further preferably 0.5 to 15% by weight, and most preferably 0.5 to 10% by weight, based on the amount of component A) as 100% by weight.

The water-insoluble salt may have a particle size of 2000 to 6000 meshes, preferably 2000 to 4000 meshes.

The water-insoluble salt is preferably a multi-valent water-insoluble inorganic salt.

The multi-valent water-insoluble inorganic salt is preferably a di-valent water-insoluble inorganic salt.

The di-valent water-insoluble inorganic salt is preferably selected from one or more of calcium carbonate, magnesium carbonate, barium carbonate, calcium phosphate, magnesium phosphate, barium phosphate, calcium oxalate, magnesium oxalate and barium oxalate, and most preferably calcium carbonate.

The amount of the thickener is 0.5 to 20% by weight, preferably 0.5 to 10% by weight, further preferably 0.5 to 5% by weight, and most preferably 0.5 to 1.5% by weight, based on the amount of component A) as 100% by weight.

The water-soluble thickener is selected from one or more of alkylated cellulose, hydroxyalkylated cellulose and carboxyalkylated cellulose.

The alkylated cellulose is selected from one or more of methylcellulose, ethylcellulose and propylcellulose.

The hydroxyalkylated cellulose is selected from one or more of hydroxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl cellulose.

The carboxyalkylated cellulose is selected from one or more of carboxymethyl cellulose, carboxyethyl cellulose and carboxypropyl cellulose, and most preferably carboxymethyl cellulose.

The textile is in contact with component A) for preferably 2 to 4 minutes, further preferably 1 to 2 minutes, and most preferably 0.2 to 1 minute.

The water content in component A) is the balance which makes the amount of component A) reach 100% by weight.

Step b)

In step b), the textile which has contacted with component A) is brought into contact with component B). The acid in component B) reacts with the water-insoluble salt in component A) which is remained on the textile, and the aqueous polymer dispersion in component B) precipitates on the surface of the textile.

The reaction temperature is preferably 80 to 180°C, and most preferably 80 to 120°C.

The reaction period is preferably 0.2 to 30 minutes, and most preferably 1 to 30 minutes.

Component B)

In step b), the textile which has contacted with component A) is brought into contact with component B) for preferably 0.2 to 4 minutes, further preferably 0.2 to 2 minutes, and most preferably 0.2 to 1 minute.

The solid content in the aqueous polymer dispersion is 10 to 50% by weight, preferably 25 to 50% by weight, based on the amount of component B) as 100% by weight.

The aqueous polymer dispersion is selected from water-soluble polymers, preferably one or more of aqueous polyurethane dispersion, aqueous polyacrylate dispersion, aqueous polybutadiene dispersion, rubber latex (water dispersion of rubber particulates), styrene -butadiene latex (water dispersion formed by the polymerization of butadiene and styrene), butadiene-acrylonitrile latex (water dispersion formed by the polymerization of butadiene and acrylonitrile) and neoprene latex (formed by the homopolymerization of polybutadiene), and most preferably aqueous polyurethane dispersion.

Aqueous polyurethane dispersion

The aqueous polyurethane dispersion has a residual organic solvent content of less than 1.0% by weight, based on the amount of aqueous polyurethane dispersion as 100% by weight.

The aqueous polyurethane dispersion has a pH value of preferably less than 9.0, further preferably less than 8.5, more preferably less than 8.0, and most preferably in a range of 6.0-8.0.

The aqueous polyurethane dispersion has a solid content in the range of preferably 10 to 70% by weight, further preferably 50 to 65% by weight, and most preferably 55 to 65% by weight, based on the amount of aqueous polyurethane dispersion as 100% by weight.

The aqueous polyurethane dispersion is preferably an aqueous anionic and/or nonionic polyurethane dispersion, most preferably an aqueous anionic polyurethane dispersion.

The aqueous anionic polyurethane dispersion comprises a small amount of hydrophilic anionic groups. The hydrophilic anionic groups are preferably in an amount of 0.1 to 15 mg equivalent/ 100 g solid polyurethane.

The aqueous anionic and/or nonionic polyurethane dispersion is preferably obtained by the following steps:

Step I) the preparation of isocyanate functional prepolymer from: la) organic polyisocyanates, lb) polymeric polyol having a number average molecular weight in a range of 400 to 8000 g/mol, preferably 400 to 6000 g/mol and particularly preferably 600 to 3000 g/mol, and a hydroxyl functionality in a range of 1.5 to 6, preferably 1.8 to 3, and particularly preferably 1.9 to 2.1,

Ic) optionally a hydroxyl-functional compound having a molecular weight in a range of 32 to 400 g/mol, and

Id) optionally an isocyanate -reactive, anionic or potentially anionic hydrophilizing agent,

Step II) reaction of all or some of the free isocyanate (NCO) groups of the isocyanate functional prepolymer with the following substances for chain extension:

Ila) optionally an amino-functional compound having a molecular weight in a range of 32 to 400 g/mol, and/or lib) an isocyanate -reactive, preferably amino-functional, anionic or potentially anionic hydrophilizing agent, where the resulting isocyanate functional prepolymer is dispersed in water before, during or after step II), where any potentially anionic groups present are converted into the ionic form by partially or completely reacting with a neutralizer, preferably after step II).

The solvents still present in the aqueous polyurethane dispersion after dispersing can be removed by distillation. The solvents can also be removed during the dispersing.

In a preferred embodiment for the preparation of aqueous polyurethane dispersion, components la) to Id) and Ila) to lib) are employed in the following amounts, where the individual amounts always add up to 100% by weight:

5 to 40% by weight of component la),

55 to 90% by weight of lb),

0.5 to 20% by weight of the sum of components Ic) and Ila),

0.1 to 25% by weight of the sum of components Id) and lib), where 0.1 to 5% by weight of anionic or potentially anionic hydrophilizing agents from Id) and/or lib) is used, based on the total amounts of components la) to Id) and Ila) to lib) as 100% by weight.

In another preferred embodiment for the preparation of aqueous polyurethane dispersion, components la) to Id) and Ila) to lib) are employed in the following amounts, where the individual amounts always add up to 100% by weight:

5 to 35% by weight of component la),

60 to 90% by weight of lb),

0.5 to 15% by weight of the sum of components Ic) and Ila),

0.1 to 15% by weight of the sum of components Id) and lib), where 0.2 to 4% by weight of anionic or potentially anionic hydrophilizing agents from Id) and/or lib) is used, based on the total amounts of components la) to Id) and Ila) to lib) as 100% by weight.

In a yet another preferred embodiment for the preparation of aqueous polyurethane dispersion, components la) to Id) and Ila) to lib) are employed in the following amounts, where the individual amounts always add up to 100% by weight:

10 to 30% by weight of component la),

65 to 85% by weight of lb), 0.5 to 14% by weight of the sum of components Ic) and Ila),

0.1 to 13.5% by weight of the sum of components Id) and lib), where 0.5 to 3.0% by weight of anionic or potentially anionic hydrophilizing agents from Id) and/or lib) is used, based on the total amounts of components la) to Id) and Ila) to lib) as 100% by weight.

In step I), the ratio of isocyanate groups in the organic polyisocyanates in component la) to isocyanate-reactive groups, such as amino, hydroxyl or thiol groups, in components lb) to Id) is in a range of 1.05 to 3.5, preferably 1.2 to 3.0, most preferably 1.3 to 2.5.

In step I), the organic polyisocyanates in component la) may be aromatic, araliphatic, aliphatic or cycloaliphatic organic polyisocyanates having an isocyanate functionality of 2. Examples are 1,4-butylene diisocyanate, 1,6-hexamethylene diisocyanate(HDI), isophorone diisocyanate (IPDI), 2,2,4- and/or 2,4,4-trimethylhexamethylene diisocyanate, isomeric bis(4,4'-isocyanatocyclohexyl)methanes or mixtures thereof with any desired isomer content, 1 ,4-cyclohexylene diisocyanate, 1 ,4-phenylene diisocyanate, 2,4- and/or 2,6-tolylene diisocyanate, 1,5-naphthylene diisocyanate, 2,2'- and/or 2,4'- and/or 4,4'-diisocyanatodiphenylmethane, 1,3- and/or 1 ,4-bis(2-isocyanatoprop-2-yl)-benzene (TMXDI), 1 ,3-bis(isocyanatomethyl)benzene (XDI), and alkyl 2,6-diisocyanato-hexanoates (lysine diisocyanates) containing Ci-C8-alkyl groups, preferably 1,6-hexamethylene diisocyanate(HDI), isophorone diisocyanate (IPDI) or isomeric bis(4,4'-isocyanatocyclohexyl)methanes or mixtures thereof.

In step I), the organic polyisocyanates in component la) can also be modified diisocyanates having a uretdione, isocyanurate, urethane, allophanate, biuret, imino-oxadiazinedione and/or oxadiazinetrione structure.

In step I), the organic polyisocyanates in component la) can further be unmodified polyisocyanates containing more than 2 NCO groups per molecule, for example, 4-isocyanatomethyloctane 1,8 -diisocyanate (nonan triisocyanate) or triphenylmethane 4,4',4"-triisocyanate.

In step I), the polymeric polyols in component lb) can be one or more of polyester polyols, polyacrylate polyols, polyurethane polyols, polycarbonate polyols, polyether polyols, polyester polyacrylate polyols, polyurethane polyacrylate polyols, polyurethane polyester polyols, polyurethane polyether polyols, polyurethane polycarbonate polyols and polyester polycarbonate polyols, which are commonly used for the preparation of aqueous polyurethane dispersion.

The polyester polyols can be polycondensates of di- and optionally tri- and tetraols with di- and optionally tri- and tetracarboxylic acids or hydroxycarboxylic acids or lactones. So long as the average functionality of the di- and optionally tri- and tetraol is greater than 2, monocarboxylic acids can also be used for condensation to synthesize polyester polyols, wherein the monocarboxylic acids can be benzoic acid and/or heptanoic acids.

The diols can be one or more of ethylene glycol, butylene glycol, diethylene glycol, triethylene glycol, polyalkylene glycols, such as polyethylene glycol, 1 ,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol and isomers thereof, neopentyl glycol and neopentyl glycol hydroxypivalate. It is preferable for one or more of 1,6-hexanediol and isomers thereof, neopentyl glycol and neopentyl glycol hydroxypivalate.

The tri- and tetraols can be one or more of trimethylolpropane, glycerol, erythritol, pentaerythritol, trimethylolbenzene and trishydroxyethyl isocyanurate.

The dicarboxylic acids can be one or more of phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, cyclohexanedicarboxylic acid, adipic acid, azelaic acid, sebacic acid, glutaric acid, tetrachlorophthalic acid, maleic acid, fumaric acid, itaconic acid, malonic acid, suberic acid, 2-methylsuccinic acid, 3,3-diethylglutaric acid and 2,2-dimethylsuccinic acid. The corresponding anhydrides can also be used as the acid source of dicarboxylic acids.

The lactones are one or more of caprolactone, caprolactone homologs, butyrolactone and butyrolactone homologs, preferably caprolactone.

The polycarbonate polyols have a number average molecular weight in a range of preferably 400 to 8000 g/mol, and most preferably 600 to 3000 g/mol.

The polycarbonate polyols preferably have linear structures, most preferably polycarbonate diols.

The polycarbonate diols preferably contain 40 to 100% by weight of hexanediol. The hexanediol is preferably 1,6-hexanediol and/or a hexanediol derivative. The hexanediol derivative is hexanediol-based and contains ester or ether groups in addition to terminal hydroxyl groups, obtainable by reaction of hexanediol with an excess amount of caprolactone or by etherification of hexanediol itself, which produces dihexanediol or trihexanediol.

The polyether polyols can be polytetramethylene glycol polyethers, obtainable by means of cationic ring opening polymerization of tetrahydrofuran.

The polyether polyols can also be products of the addition of styrene oxide, ethylene oxide, propylene oxide, butylene oxide and/or epichlorohydrin onto di- or polyfunctional starter molecules.

The starter molecules can be one or more of water, butyl diglycol, glycerol, diethylene glycol, trimethylolpropane, propylene glycol, sorbitol, ethylenediamine, ethylene glycol, triethanolamine and 1 ,4-butanediol.

The lb) polymeric polyols most preferably comprise polycarbonate polyols and polybutylene glycol polyols. The polycarbonate polyols and polybutylene glycol polyols are present in an amount of at least 50% by weight, preferably 60% by weight, and particularly preferably 70% by weight, based on the amount of polymeric polyols as 100% by weight.

The polycarbonate polyols are present in an amount of 20 to 80% by weight, preferably 25 to 70% by weight, and most preferably 30 to 65% by weight, based on the sum of the weights of polycarbonate polyols and polybutylene glycol polyols as 100% by weight. The polybutylene glycol polyols are present in an amount of 20 to 80% by weight, preferably 30 to 75% by weight, and most preferably 35 to 70% by weight, based on the sum of the weights of polycarbonate polyols and polybutylene glycol polyols as 100% by weight.

The Ic) hydroxyl-functional compounds can be polyols having up to 20 carbon atoms, such as one or more of ethylene glycol, diethylene glycol, triethylene glycol, 1 ,2-propanediol, 1,3-propanediol, 1 ,4-butanediol, 1,3-butylene glycol, cyclohexanediol, 1 ,4-cyclohexanedimethanol, 1,6-hexanediol, neopentyl glycol, hydroquinone dihydroxyethyl ether, bisphenol A (2,2-bis(4-hydroxyphenyl)propane), hydrogenated bisphenol A (2,2-bis(4-hydroxycyclohexyl)propane), trimethylol propane, glycerol and pentaerythritol.

The Ic) hydroxyl-functional compounds can also be ester diols, such as one or more of a-hydroxybutyl-e-hydroxycaproic acid esters, co-hydroxyhexyl-y-hydroxybutyric acid esters, β-hydroxyethyl adipate or β-hydroxyethyl terephthalate.

The Ic) hydroxyl-functional compounds can further be monofunctional or isocyanate-reactive, hydroxyl function-containing compounds. The monofunctional or isocyanate-reactive, hydroxyl function-containing compounds can be one or more of ethanol, n-butanol, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, dipropylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, 2-ethylhexanol, 1-octanol, 1-dodecanol, 1 -hexadecanol, 1,6-hexanediol, 1,4-butylene glycol, neopentyl glycol and trimethylol propane, preferably one or more of 1,6-hexanediol, 1,4-butylene glycol, neopentyl glycol and trimethylol propane. The Id) isocyanate -reactive, anionic or potentially anionic hydrophilizing agents comprise a compound containing at least one isocyanate -reactive group(s), such as a hydroxyl group, and at least one functional group(s), such as -COO^"M⁺, -S0 ^~M⁺, -PO(0^"M⁺)₂, where M⁺ can be a metal cation, H⁺, NH⁴⁺, NHR ⁺, where R can be a Ci-Ci2-alkyl, C5-C6-cycloalkyl and/or C₂-C4-hydroxyalkyl group. The functional group enters into a pH-dependent dissociation equilibrium upon the interaction with aqueous media and may thus be negatively or neutrally charged.

The Id) isocyanate-reactive, anionic or potentially anionic hydrophilizing agents are preferably mono- and dihydroxycarboxylic acids, mono- and dihydroxysulfonic acids, and mono- and dihydroxyphosphonic acids, and salts thereof. Further preferably, carboxylate or carboxylic acid groups and/or sulfonate groups are contained.

The Ila) amino-functional compounds are selected from one or more of 1 ,2-ethylenediamine, 1 ,4-diaminobutane and isophoronediamine.

The lib) anionic or potentially anionic hydrophilizing agents comprise a compound containing at least one isocyanate-reactive group(s), such as an amino group, and at least one functional group(s), such as -COO^"M⁺, -S0 ^~M⁺, -PO(0^~M⁺)₂, where M⁺ can be a metal cation, H⁺, NH⁴⁺, NHR ⁺, where R can be a Ci-Ci₂-alkyl, C5-C6-cycloalkyl and/or C₂-C4-hydroxyalkyl group. The functional group enters into a pH-dependent dissociation equilibrium upon the interaction with aqueous media and may thus be negatively or neutrally charged.

The aqueous polyurethane dispersion may be prepared by using the prepolymer mixing process, acetone process or melt dispersal process, and the acetone process is preferably used.

According to the acetone process, all or some of la) to Id) are usually initially introduced for the preparation of an isocyanate-functional prepolymer and optionally diluted with a solvent which is miscible with water, but inert to isocyanate groups and heated to temperatures in the range from 50 to 120^°C .

The solvents can be the conventional aliphatic, keto-functional solvents, such as acetone, 2-butanone. The solvents can be added only at the beginning of the preparation, if desired, can also partly be added further during the preparation.

The solvents can also be xylene, toluene, cyclohexane, butyl acetate, methoxypropyl acetate, N-methylpyrrolidone, N-ethylpyrrolidone, or solvents containing ether or ester units.

Any la) to Id) components which have not yet been added at the beginning of the reaction are subsequently metered in. In the preparation of an isocyanate-functional prepolymer from components la) to Id), the molar ratio of isocyanate groups to isocyanate-reactive groups is in a range of 1.05 to 3.5, preferably 1.2 to 3.0, and most preferably 1.3 to 2.5.

The conversion of components la) to Id) into the isocyanate-functional prepolymer is carried out in part or full, preferably in full.

The isocyanate-functional prepolymer obtained by step I) can be in the solid state or in the liquid state.

If the resulting isocyanate-functional prepolymer has not been dissolved or is only dissolved in part, the prepolymer is further dissolved with the aid of aliphatic ketones, such as acetone or 2-butanone.

In step II), NH₂ ^~ and/or NH -functional components are reacted in part or full with the remaining isocyanate groups of the isocyanate-functional prepolymer. The chain extension or termination is preferably carried out before dispersing in water.

For the chain termination, Ila) amino-functional compounds, such as methylamine, ethylamine, propylamine, butylamine, octylamine, laurylamine, stearylamine, isononyloxypropylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, N-methylaminopropylamine, diethyl(methyl)aminopropylamine, morpholine, piperidine, or suitable substituted derivatives thereof, amidoamines made from diprimary amines and monocarboxylic acids, monoketimes of diprimary amines or primary/tertiary amines, such as Ν,Ν-dimethylaminopropylamine, are usually used.

The components Ila) and lib) can optionally be employed in water- or solvent-diluted form individually or in mixtures, where any sequence of addition is possible.

Aqueous polyacrylate dispersion, aqueous polybutadiene dispersion

The preparation of the aqueous polyacrylate dispersion and aqueous polybutadiene dispersion can be carried out according to the known free-radical polymerization process, such as solution polymerization, emulsion polymerization and suspension polymerization. The preparation can be continuous or discontinuous, preferably discontinuous.

The aqueous polyacrylate dispersion and aqueous polybutadiene dispersion can be selected from commercially available products.

Acids able to react with water-insoluble salts

The acid may be in an amount of 0.1 to 50% by weight, preferably 0.5 to 5% by weight, based on the amount of component B) as 100% by weight. The acid may have a concentration of 1 to 20%, and preferably 5 to 10%.

The acid is selected from one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, formic acid and acetic acid.

Step c)

The process for coating a textile provided by the invention may further comprises a step c), bringing the textile contacted with component B) into contact with water to wash off the water-soluble components on the surface of the coated textile or within the gaps of textile fibers.

The temperature of the water is 0 to 90°C. The textile contacted with component B) is in contact with water for preferably 2 to 4 minutes, further preferably 1 to 2 minutes, and most preferably 0.2 to 1 minute.

After the textile contacts with water in step c), it generally needs a squeezer device to wring the textile. Step c) and the wringing step may be repeated, such as more than three times, and followed by after-treatments, such as drying. The winging process is conducted in such a way that the liquid remains in the textile in an amount of 30 to 400% by weight, preferably 30 to 180% by weight, further preferably 30 to 140% by weight, and most preferably 30 to 120% by weight. The amount of liquid remained in the textile is the proportion of the weight of the residual liquid in the textile to the total weight of the textile (including the residual liquid).

Squeezing and Drying

A part of or all of the liquid in the textile from step a), step b) or step c) can be removed, prior to the textile being subjected to the subsequent step.

The process for removing a part of or all of the liquid in the textile may be squeezing and/or drying.

The squeeze step may refer to squeeze the textile with a squeezer device comprising two rollers to enable the liquid remained in the textile in an amount of 30 to 400% by weight, preferably 30 to 180% by weight, further preferably 30 to 140% by weight, and most preferably 30 to 120% by weight. The amount of liquid remained in the textile is the proportion of the weight of the residual liquid in the textile to the total weight of the textile (including the residual liquid).

The drying may refer to physical drying or chemical drying. The duration for drying is preferably 1 to 10 minutes, and most preferably 1 to 5 minutes. The temperature for drying is 70 to 150°C. A part of or all of the textile can be dried during the drying process.

The physical drying may refer to air drying, infrared cylinder or hot cylinder drying.

The chemical drying may refer to drying by bringing the textile into contact with a cros slinking agent.

The crosslinking agent can be a crosslinking agent based on isocyanates, melamines, aziridines or carbodiimides.

The textile can be treated with additives prior to, during or after coating, preferably prior to coating. The additives are selected from dyes, colorants, pigments, UV absorbers, plasticizers, soil redeposition agents, lubricants, antioxidants, flame inhibitors or rheology agents.

The process for coating a textile provided by the invention, on the one hand, is advantageous for the health of operators and does not need additional steps for the separation of organic solvents, by using aqueous components in place of organic solvents. On the other hand, water-insoluble salts contact with acids which is able to react with water-insoluble salts to gradually release metal ions which slowly precipitate together with aqueous polymer dispersion on the surface of the textile. The invention not only extends the operable period for coating textiles, but also provides water-soluble thickeners with enough time to enter the gaps of textile fibers, thus reduces the precipitate of aqueous polymer dispersion within the gaps of the textile fibers. In the subsequent washing stage, the water-soluble thickener within the gaps of the textile fibers is washed off so as to release the gaps of the textile fibers to impart the coated textile with a good hand feeling. In another aspect, water-insoluble salts react with acids which is able to react with water-insoluble salts to release gases, such as carbon dioxide, which are able to enter into the precipitate as the aqueous polymer dispersion precipitates to impart the precipitate with elasticity and further optimize the good hand feeling of the coated textile.

Examples

All percentages used in the present invention are weight percentages, unless otherwise indicated.

Feedstocks and reagents

CMC FH6 carboxymethyl cellulose, purchased from Shanghai

Shenguang Edible Chemicals Co., Ltd., used as a water-soluble thickener for component A).

Ca(C0₃)₂ particle size: 2500 meshes, purchased from Shanghai

Duosen Chemical Co., Ltd., used as a water insoluble salt for component A).

Impranil DLE aqueous polyurethane dispersion having a pH value of 7.0 and a solid content of 50% by weight, purchased from Covestro Polymers (China) Co., Ltd., used as an aqueous polymer dispersion for component B).

Acetic acid concentration: 5%, purchased from Shanghai Duosen

Chemical Co., Ltd., used as an acid for component B) that is able to react with the water insoluble salts in component A).

Process for the preparation of component A)

Ca(C0₃)₂ 0.7 wt%

CMC FH6 0.8 wt%

Water 98.5 wt%

Water was charged into a vessel according to the proportions listed above and then stirring was started. CMCFH6 was added into the vessel. After the liquid in the vessel turned to transparent from turbid, Ca(C03)₂ was added therein and the mixture was stirred for 40 to 60 minutes to give component A) solution.

Process for the preparation of component B)

Impranil DLE 50 wt%

Acetic acid 0.5 wt%

Water 49.5 wt%

Water was charged into a vessel according to the proportions listed above and then stirring was started. Impranil DLE and acetic acid were added into the vessel, and the mixture was stirred for 5 to 10 minutes to give component B) solution.

Example 1

A microfiber nonwoven was dipped in component A) for 12 seconds, then was taken out and squeezed with a squeezer device at a pressure of 4 bars to enable the liquid remained in the microfiber nonwoven in an amount of 120%. Subsequently, it was dried at a temperature range of 110 to 140°C for 5 minutes. After that, the microfiber nonwoven was dipped in component B) for 15 seconds, then was taken out and placed at 80°C for 10 minutes to leave Impranil DLE precipitating on the surface of the microfiber nonwoven. Subsequently, the microfiber nonwoven was squeezed with a squeezer device at a pressure of 4 bars to enable the liquid remained in the microfiber nonwoven in an amount of 150%. After dried at 90°C for 3 minutes, the microfiber nonwoven was dipped in water at 80°C to be washed for 1 minute and then squeezed with a squeezer device at a pressure of 4 bars to enable the liquid remained in the microfiber nonwoven in an amount of 30%. The washing and squeezing steps were repeated four times. Finally, the microfiber nonwoven was squeezed completely with the squeezer device and was dried at 110 to 150°C for 5 minutes to obtain a coated microfiber nonwoven.

Example 2

A single-face pile knitted textile was dipped in component A) for 60 seconds, then was taken out and squeezed with a squeezer device at a pressure of 4 bars to enable the liquid remained in the single-face pile knitted textile in an amount of 180%. Subsequently, the single-face pile knitted textile was dipped in component B) for 120 seconds, then was taken out and placed at 100°C for 20 minutes to leave Impranil DLE precipitating on the surface of the single-face pile knit textile. After dried at 90°C for 3 minutes, the single-face pile knitted textile was dipped in water at 50°C to be washed for 2 minutes and then squeezed with a squeezer device at a pressure of 4 bars to enable the liquid remained in the single-face pile knitted textile in an amount of 80%. The washing and squeezing steps were repeated four times. Finally, the single-face pile knitted textile was squeezed completely with the squeezer device, and was dried at 110 to 150°C for 5 minutes to obtain a coated single-face pile knitted textile.

Comparative Example 1

A microfiber nonwoven was dipped in a solution comprising 1 wt% CaCl₂, 0.8 wt% CMC FH6, 0.2 wt% BYK 349 and 98 wt% water for 12 seconds, then was taken out and squeezed with a squeezer device at a pressure of 4 bars to enable the liquid remained in the microfiber nonwoven in an amount of 120%. Subsequently, it was dried at a temperature range of 110 to 140°C for 5 minutes. After that, the microfiber nonwoven was dipped in a solution comprising 50 wt% Impranil DLE and 50 wt% water for 15 seconds, then was taken out and placed at 80°C for 10 minutes to leave Impranil DLE precipitating on the surface of the microfiber nonwoven. Subsequently, the microfiber nonwoven was squeezed with a squeezer device at a pressure of 4 bars to enable the liquid remained in the microfiber nonwoven in an amount of 150%. After dried at 90°C for 3 minutes, the microfiber nonwoven was dipped in water at 80°C to be washed for 1 minute and then was squeezed with a squeezer device at a pressure of 4 bars to enable the liquid remained in the microfiber nonwoven in an amount of 30%. The washing and wringing steps were repeated four times. Finally, the microfiber nonwoven was squeezed completely with the squeezer device and was dried at 110 to 150°C for 5 minutes to obtain a coated microfiber nonwoven.

By comparing the examples with the comparative example, it is found that the coated textile obtained in the comparative example has a stiff hand feeling, and there are creases and slumps easily occurring after the textile is folded and released, whereas the textile obtained by coating according to the processes described in the examples has a soft hand feeling, and there will be no creases and slumps occurring after the textile is folded and released.

It would be readily known for one of the skilled in the art that the present invention is not merely limited to the aforementioned specific details, but also can be performed in other particular forms with the proviso of not deviating from the spirit or major features of the present invention. Thus, no matter from which viewpoint, the Examples should be regarded as exemplary rather than limiting, and therefore, the scope of the present invention should be presented out according to the claims rather than the above description. Accordingly, any change, as long as it is within the meanings and the scopes of equivalents of the claims, should be regarded as pertained to the present invention.

Claims

1. A process for coating a textile, comprising the steps of: a) bringing the textile into contact with component A) which comprises a water-insoluble salt, a water-soluble thickener and water; and b) bringing the textile contacted with component A) into contact with component B) which comprises an aqueous polymer dispersion and an acid that is able to react with the water-insoluble salt in component A), to obtain a coated textile.

2. The process according to claim 1 , characterized in that the water-insoluble salt is a multi-valent water-insoluble inorganic salt.

3. The process according to claim 2, characterized in that the multi-valent water-insoluble inorganic salt is a di-valent water-insoluble inorganic salt.

4. The process according to claim 3, characterized in that the di-valent water-insoluble inorganic salt is selected from one or more of calcium carbonate, magnesium carbonate, barium carbonate, calcium phosphate, magnesium phosphate, barium phosphate, calcium oxalate, magnesium oxalate and barium oxalate.

5. The process according to claims 1 to 4, characterized in that the water- insoluble salt is present in an amount of 0.5 to 50% by weight, based on the amount of component A) as 100% by weight.

6. The process according to claim 1 , characterized in that the water-soluble thickener is selected from one or more of alkylated cellulose, hydroxyalkylated cellulose and carboxyalkylated cellulose.

7. The process according to claim 6, characterized in that the carboxyalkylated cellulose is carboxymethyl cellulose.

8. The process according to claim 1, 6 or 7, characterized in that the water-soluble thickener is present in an amount of 0.5 to 20% by weight, based on the amount of component A) as 100% by weight.

9. The process according to claim 1, characterized in that the aqueous polymer dispersion is selected from one or more of aqueous polyurethane dispersion, aqueous polyacrylate dispersion, aqueous polybutadiene dispersion, rubber latex, styrene-butadiene latex, butadiene-acrylonitrile latex and neoprene latex.

10. The process according to claim 9, characterized in that the aqueous polyurethane dispersion is an aqueous anionic polyurethane dispersion.

11. The process according to claim 1, 9 or 10, characterized in that the solid content in the aqueous polymer dispersion is 10 to 50% by weight, based on the amount of component B) as 100% by weight.

12. The process according to claim 1, characterized in that the acid is selected from one or more of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, formic acid and acetic acid.

13. The process according to claim 1 or 12, characterized in that the acid is present in an amount of 0.1 to 50% by weight, based on the amount of component B) as 100% by weight.

14. The process according to claim 1, further comprising a step c): bringing the textile contacted with component B) into contact with water.

15. The process according to claim 1, characterized in that the process is carried out in the absence of organic solvents.

16. A coated textile, obtained by carrying out the process according to any one of claims 1 to 15.

17. The coated textile according to claim 16, characterized in that the coated textile is free of water-insoluble salt.

18. The coated textile according to claim 16 or 17, characterized in that the coated textile is synthetic leather.