TWI589751B - Process for the coating of textiles - Google Patents

Description

Method of coating fabric

The present invention is directed to a method of making a coated fabric wherein the fabric substrate is first contacted with an aqueous dispersion comprising at least one inorganic salt and at least one modified cellulose.

It has been known for a period of time that the manufacture of synthetic leather coated with plastic is used for a period of time including synthetic topping materials, for clothing, packaging materials or for furniture parts. In addition to other plastics, such as PVC, the primary coating material used herein is a polyurethane. The generally known principles of coated fabrics with polyurethanes have been described in W. Schröer, Textilveredlung [Textile Finishing] 1987, 22(12), 459-467. A description of this coagulation process can be found in "New Materials Permeable to Water Vapor", Harro Träubel, Springer Verlag, Berlin, Heidelberg, New York, 1999, ISBN 3-540-64946-8, pages 42 to 63.

The main methods used in the manufacture of synthetic leather are the direct coating method, the transfer coating method (indirect coating), and the coagulation (wet) method. With respect to the direct method, the coating system in the transfer method is applied to a temporary support, followed by a subsequent lamination step, wherein the film is bonded to the fabric substrate and is detached from the temporary support (out of shape) paper). The transfer process is preferably applied with a fabric substrate that does not allow high tensile stress when applied or with unopened open fabrics.

In the coagulation process, the fabric substrate is usually coated with a solution comprising a polyurethane in DMF, and in the second step, the coated substrate is passed through a DMF/water bath wherein the proportion of water The gradual increase, the deposition of the polyurethane and the formation of microporous membranes occur here. It is based on the fact that DMF and water have excellent compatibility, and DMF and water are used as a solvent/non-solvent combination of polyurethanes. Coagulation of polyurethane coatings, especially for high quality synthetic leathers, because they have relatively good respiration and leather sense. The basic principle of this coagulation process is based on the use of a suitable solvent/non-solvent combination of polyurethanes. An important advantage of this coagulation process is the ability to obtain microporous, breathable synthetic leather with excellent leather feel. Examples are, for example, the synthetic leather brand Clarino® and Alcantara®. A disadvantage of this coagulation process is that a large amount of DMF must be used as an organic solvent. In order to minimize employee contact with DMF emissions at the time of manufacture, additional design measures must be implemented that represent an increased setting compared to a simpler method. Furthermore, a large amount of DMF/water mixture needs to be disposed of or treated because water and DMF form an azeotrope and thus can only be separated by distillation and increased effort, thus causing problems.

It is therefore an object of the present invention to develop a method of coating a textile substrate which still enables a fabric substrate having good properties, such as good feel, to be obtained without the application of a toxicologically unacceptable solvent such as DMF.

This object is achieved by a method of making a coated fabric comprising at least the following steps: a) bringing a textile substrate into contact with an aqueous dispersion A having at least one inorganic salt and at least one modified cellulose; b) bringing a fabric substrate into contact with an aqueous dispersion B having at least one polymer selected from the group consisting of polyacrylates and polybutadiene; c) being selected from the group consisting of At least one polymer of the group consisting of acrylate and polybutadiene is deposited in or on the textile substrate.

In step a), a fabric substrate is contacted with an aqueous solution comprising at least one inorganic salt and at least one modified cellulose.

The inorganic salt is preferably selected from the group consisting of alkali metal salts and alkaline earth metal salts. The inorganic salt is particularly preferably selected from the group consisting of alkali metal halides, alkali metal phosphates, alkali metal nitrates, alkali metal sulfates, alkali metal carbonates, alkali metal hydrogencarbonates, alkaline earth metal halides, and alkaline earth metals. A salt of the group consisting of metal nitrates, alkaline earth metal phosphates, alkaline earth metal sulfates, alkaline earth metal carbonates, and alkaline earth metal hydrogencarbonates. The inorganic The salt is preferably sodium chloride, potassium chloride, sodium sulfate, sodium carbonate, potassium sulfate, potassium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate, magnesium chloride, magnesium nitrate, calcium chloride, calcium nitrate or calcium sulfate. Even more preferably, the inorganic salt is calcium nitrate, magnesium nitrate, calcium chloride or magnesium chloride.

The inorganic salt is preferably present in the dispersion A in an amount of from 0.01 to 25% by weight based on the total amount of the dispersion A, particularly preferably from 0.5 to 15% by weight, particularly preferably from 0.5 to 10% by weight. The amount used.

The chemically modified cellulose is preferably a compound selected from the group consisting of alkylated cellulose, hydroxyalkylated cellulose, and carboxyalkylated cellulose.

The chemically modified cellulose is particularly preferably selected from the group consisting of methyl cellulose, ethyl cellulose, propyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxymethyl cellulose, and hydroxypropyl. A compound of the group consisting of methylcellulose, carboxymethylcellulose, carboxyethylcellulose, and carboxypropylcellulose.

Very preferred of the chemically modified cellulose is methyl cellulose or ethyl cellulose.

The modified cellulose is preferably present in the dispersion A in an amount of from 10 ppm to 5% by weight based on the total amount of the dispersion A, particularly preferably from 100 ppm to 3% by weight, very particularly 400 The amount is from ppm to 1.5% by weight.

The fabric substrate is preferably contacted with an aqueous dispersion A at room temperature for a period of from 2 to 4 minutes, particularly preferably from 1 to 2 minutes, and very preferably from 0.2 to 1 minute. For the purposes of the present invention, contact means a partially or completely impregnated, in particular fully immersed in a dispersion or a dispersion for manual coating, printing or spraying.

After contacting the dispersion A, the fabric substrate is preferably passed through a twisting device of two rollers to remove excess dispersion A, where the twisting device is preferably set to be carried in the substrate. Before the dispersion B containing at least one polymer selected from the group consisting of polyacrylates and polybutadiene, the dispersion A is made 60 based on the weight per unit area of the substrate (liquid absorption). The amount to 180% by weight is maintained on the textile substrate, particularly preferably from 70 to 140% by weight, very particularly preferably from 80 to 120% by weight. The fabric substrate is preferably air, infrared or heat before it is brought into contact with the dispersion B containing at least one polymer selected from the group consisting of polyacrylates and polybutadiene. The barrel is partially dried for a period of 2 to 10 minutes, particularly preferably 1 to 5 minutes.

The polyacrylate and polybutadiene of the dispersion B are not particularly limited as long as they are soluble in water.

The polyacrylate polymer is prepared from a hydroxyl group-containing monomer, an "acidic" monomer, or a monomer which is neither acidic nor OH-based.

Suitable hydroxyl-containing monomers include hydroxyalkyl acrylates or methacrylates, preferably those having from 2 to 4 carbon atoms, such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate Esters, 2- or 3-hydroxypropyl acrylates as well as methacrylates, isomeric hydroxybutyl acrylates and methacrylates and mixtures of these monomers.

Suitable "acidic" comonomers include ethylenically unsaturated, polymerizable compounds comprising at least one carboxyl and/or sulfonic acid group, for example an ethylenically unsaturated monocarboxylic or dicarboxylic acid having a molecular weight of from 72 to 207. Examples include acrylic acid, methacrylic acid, maleic acid, itaconic acid, and ethylenically unsaturated compounds containing a sulfonic acid group, such as 2-propenylamine-2-methylpropanesulfonic acid and such ethylenically unsaturated acids. mixture.

A third population of ethylenically unsaturated monomers which may be involved in the preparation of the acrylate polymer, including ethylenically unsaturated compounds, which do not comprise an acid group or a hydroxyl group. Examples include esters of acrylic acid or methacrylic acid having from 1 to 18 carbon atoms in an alcohol radical, preferably having from 1 to 8 carbon atoms, such as methyl acrylate, ethyl acrylate, isopropyl acrylate. Ester, n-propyl acrylate, n-butyl acrylate, ethylhexyl 2-acrylate, isobornyl acrylate, n-stearyl acrylate, methacrylate, methacrylate relative to the above acrylate, styrene, Alkyl-substituents of styrene, butadiene, isoprene, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl stearate, and mixtures of these monomers. The epoxy group-containing comonomer may be a glycidyl acrylate or methacrylate or monomer such as N-methoxymethyl acrylamide or N-methyl acrylamide, which may also be small. The use of quantity.

The production of an aqueous dispersion containing polyacrylate and/or polybutadiene is carried out according to a known radical polymerization method, for example, solution polymerization, emulsion polymerization, and suspension polymerization. A free radical emulsion polymerization method in an aqueous medium is preferred.

Continuous or discontinuous polymerization can be used. Examples of discontinuous processes are batch processing and feed methods, the latter being preferred. In this feed method, water is added separately or emulsified with a portion of the anion. The agent, together with an optional nonionic emulsifier, is added along with a portion of the monomer mixture and heated to the polymerization temperature. In the case of monomer addition, the polymerization is initiated by a free radical and the remaining monomer mixture is metered in with a starter mixture and the emulsifier for 1 to 10 hours, preferably 3 to 6 hours. . If desired, the reaction mixture is then post-activated to effect polymerization to a conversion of at least 99%.

The emulsifier used may be anionic and/or nonionic. The anionic emulsifier comprises a functional group such as a carboxylate, a sulfate, a sulfonate, a phosphate or a phosphonate. Preferred emulsifiers may be functional groups such as sulfates, sulfonates, phosphates or phosphonates. The emulsifier can be low molecular weight or high molecular weight. The latter case is described, for example, in DE-A 3 806 066 and DE-A 1 953 349.

Preferred anionic emulsifiers may be bonded to the hydroxyl group by long chain alcohols or substituted phenol and polyether chains, while the carboxyl groups have 2 to 100 ethylene oxide units, and the functional groups of sulfuric acid or phosphoric acid are The form of the ester unit is bonded thereto. Preferred unesterified acid-based neutralizers may be ammonia or an amine. The emulsifier can be added to the emulsified batch either singly or as a mixture.

Suitable nonionic emulsifiers may be the reaction product of an aliphatic, aromatic aliphatic, cycloaliphatic or aromatic carboxylic acid, an alcohol, a phenol derivative and/or an epoxide-containing amine such as ethylene oxide. It can also be used in combination with an anionic emulsifier. Examples include the use of a reaction product of ethylene oxide with castor oil carboxylic acid and rosin acid; use of long chain alcohols such as oleyl alcohol, lauryl alcohol, stearyl alcohol; use with phenolic derivatives such as benzyl A phenol substituent, a phenylphenol substituent, and a nonylphenol substituent; an amine having a long chain such as dodecylamine and stearylamine is used. The reaction product having ethylene oxide comprises an oligomeric polyether and/or a polyether having a degree of polymerization of between 2 and 100, preferably between 5 and 50.

The emulsifier is added in an amount of from 0.1 to 10 wt.%, which is calculated as a mixture of monomers. Suitable cosolvents include water soluble and water insoluble solvents. Suitable cosolvents include aromatic compounds such as benzene, toluene, xylene and chlorobenzene; ester compounds such as ethyl acetate, butyl acetate, methyl glycol acetate, ethyl glycol B Ethyl esters and propyl methoxyacetate; ether compounds, such as ethylene glycol butyl ether, tetrahydrofuran, two Alkane, ethyl glycol ether and diethylene glycol ether; ketone compounds such as acetone, methyl ethyl ketone, methyl isobutyl ketone; trichloromonofluoroethane; and cyclic guanamine compounds, like N-methylpyrrolidone and N-methyl caprolactam.

The free radical-initiated polymerization is initiated by a water-soluble or non-aqueous initiator or initiator system which has a free radical decomposition half-life between 10 ° C and 100 ° C of from 0.5 seconds to 7 hours.

In general, the polymerization can be carried out in water at the aforementioned temperature range, preferably at a temperature between 30 ° C. and 90 ° C., preferably at a pressure of 10 ³ to 2 × 10 ⁴ mbar. Depending on the type of initiator, the exact polymerization temperature can be obtained. The amount of the initiator to be used may be 0.05 to 6 wt.%, which is calculated based on the total amount of the monomers.

Suitable starters include water-soluble or non-aqueous azo compounds such as azoisobutyronitrile or 4,4'-azo-bis-(4-cyanovaleric acid); inorganic and organic peroxides, like Is benzoic acid benzoate; tertiary butyl perpivalate, tertiary butyl-per-2-ethylhexanoate, tertiary butyl perbenzoate, tertiary butyl hydroperoxide , di-tertiary butyl peroxide, cumene hydroperoxide, dicyclohexyl dicarbonate, dibenzyl peroxydicarbonate, sodium peroxodisulfate, potassium and ammonium salts and hydrogen peroxide .

In order to adjust the molecular weight of the polymer, common regulators such as n-dodecyl mercaptan, tertiary lauryl mercaptan, diisopropyl xanthogen disulfide, and di(methylene-trihydroxyl) can be used. Methylpropane) xanthogen disulfide and thioglycol. The modifier can be added up to 3 wt.%, which is calculated as a monomer mixture.

After the end of the polymerization reaction, if necessary, a neutralizing agent may be added to the polymer of the aqueous dispersion to obtain a degree of neutralization of from 30 to 100%, preferably from 50% to 100%. The inorganic phase, ammonia or amine is added as a neutralizing agent to the above polymers. Examples include inorganic phases such as sodium hydroxide and potassium hydroxide; and amines such as ammonia, trimethylamine, triethylamine, dimethylethanolamine, methyldiethanolamine, and triethanolamine. The neutralizing agent can be used in an amount that is less than stoichiometric or exceeds stoichiometry, with the result being the sulfonate and/or carboxylate functional groups mentioned above, particularly the carboxylate functional groups and the above acid numbers.

If the acid group is completely neutralized, the acid number can be zero, such as the content of the sulfonate and/or carboxylate functional group corresponding to the content of the original sulfonic acid and/or carboxylic acid functional group. When partial neutralization occurs, the amount of sulfonate and/or carboxylate functional groups will correspond to the level of neutralizing agent. The resulting aqueous dispersion has the above concentrations and viscosity. In the aqueous dispersion, the selective co-solvent may also be maintained in the above amounts or may be removed by distillation after the polymerization.

The preferred aqueous dispersion B containing polyacrylate is sold under the brand name Primal® and is commercially available from Rohm and Hass, Philadelphia, Pa., USA.

A preferred aqueous dispersion B preferably containing polybutadiene may be Euderm®-Resin 40B and Euderm®-Resin 50B.

In a further embodiment, dispersion B comprises at least one coagulant and excludes a polymer selected from the group consisting of polyacrylates and polybutadienes. The coagulant may be a salt or an acid, for example, an amine salt of an organic acid, which in certain instances may produce a polymer selected from the group consisting of polyacrylates and polybutadienes. Aggregate, and the specific case can be a special temperature. These substances include acidogenic chemicals, such as a substance that is not an acid at room temperature, but forms an acid upon heating. Examples of certain such compounds include ethylene glycol diacetate, ethylene glycol formate, diglycol formate, triethyl citrate, monostearyl citrate, and organic acid esters.

The coagulant may preferably be used in an amount of from 1 to 10% by weight based on the solid content of the dispersion B.

In order to achieve good sedimentation stability, the number average particle size of the particular polyacrylate dispersion and polybutadiene is preferably less than 750 nm, particularly preferably less than 500 nm and very particularly preferably less than 400. Nm, and the particle size is tested using a laser particle size analyzer.

The manner of sedimentation on or in the fabric substrate depends on the chemical composition of the plurality of dispersions B in accordance with the present invention, especially when the types of coagulants are different. For example, sedimentation can be coagulated by evaporative coagulation or by salts, acids or electrolytes.

In general, coagulation can be achieved by an increase in temperature. For example, the fabric substrate can be briefly heat treated with steam, for example, from 100 to 110 ° C for 1 to 10 s. A particularly preferred coagulant may be an ammonium salt or an organic acid. On the other hand, if the above-mentioned acid-producing chemical is used as the coagulant, the sedimentation can be preferably carried out as described in US 5,916,636, US 5,968,597, US 5,952,413 and US 6,040,393.

Conversely, when coagulation is produced by immersion in a salt solution. This coagulation preferably uses an inorganic salt selected from the group consisting of alkali metal salts and alkaline earth metal salts. Particularly preferred inorganic salts are selected from the group consisting of alkali metal halides, alkali metal nitrates, alkali metal phosphates, alkali metal sulfates, and alkali gold. It is a salt of a group consisting of carbonate, alkali metal hydrogencarbonate, alkaline earth metal halide, alkaline earth metal phosphate, alkaline earth metal nitrate, alkaline earth metal sulfate, alkaline earth metal carbonate and alkaline earth metal hydrogencarbonate. Very particularly preferred inorganic salts may be sodium chloride, potassium chloride, sodium sulfate, sodium carbonate, potassium sulfate, potassium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate, magnesium chloride, magnesium sulfate, calcium chloride or calcium sulfate. More preferred inorganic salts may be calcium chloride or magnesium chloride.

Preferred inorganic salt solutions may have a concentration of from 1 to 25 wt.%, particularly preferably from 1 to 15 wt.%, very particularly preferably from 1 to 10 wt.%, which is based on the total amount of the salt solution. Recalculation.

After the settling step C), the drying or condensation reaction is further carried out if necessary.

The fabric substrate may preferably be a natural, / synthetic, woven, knitted or non-woven fabric. The fabric substrate is particularly preferably non-woven (staple fiber non-woven fabric, microfiber non-woven fabric or the like).

The fabric substrate is preferably polyester, nylon (6 or 6, 6), cotton, polyester/cotton blend, wool, ramie, elastane, glass, thermoplastic polyurethane (TPU), thermoplastic olefin (TPO) or the like. Made of fibers such as objects. The fabric substrate has a joined/mesh (knitted), woven or non-woven structure.

Whether before or after coating, the textile substrate can use dyes, colorants, pigments, UV absorbers, plasticizers, soil redeposition agents, lubricants, antioxidants, flame suppressants, rheological agents, and the like. . However, these additional treatments are preferably carried out prior to coating.

If a defined non-woven fabric is impregnated and solidified with an elastomeric polymer, and then subjected to a normal coloring process, a suede-like artificial leather having good color properties can be obtained.

The invention therefore further relates to a coated fabric, preferably a synthetic leather obtained by the process of the invention.

Claims (11)

A method of preparing a coated fabric, comprising at least the steps of: a) contacting a textile substrate with an aqueous dispersion A having at least one inorganic salt and at least one modified cellulose; b) fabricating the substrate with From contact with an aqueous dispersion B of at least one polymer of the group consisting of polyacrylates and polybutadiene; c) selected from the group consisting of polyacrylates and polybutadiene At least one polymer is deposited in or on the fabric substrate. The method according to the first aspect of the invention, wherein the inorganic salt is a salt selected from the group consisting of alkali metal salts and alkaline earth metal salts. According to the method of claim 2, wherein the alkali metal salt is one selected from the group consisting of alkali metal halides, alkali metal nitrates, alkali metal phosphates, alkali metal sulfates, alkali metal carbonates, and alkali metal hydrogencarbonates. Salt. According to the method of claim 2, wherein the alkaline earth metal salt is one selected from the group consisting of alkaline earth metal halides, alkaline earth metal nitrates, alkaline earth metal phosphates, alkaline earth metal sulfates, alkaline earth metal carbonates and alkaline earth metal hydrogencarbonates. Salt. The method of claim 1, wherein the inorganic salt concentration in the dispersion A is from 0.01 to 25 wt.%, based on the total weight of the dispersion A. According to the method of claim 1, wherein the modified cellulose is one selected from the group consisting of methyl cellulose, ethyl cellulose, propyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl fibers. a compound of hydroxypropylmethylcellulose, carboxymethylcellulose, carboxyethylcellulose and carboxypropylcellulose. According to the method of claim 1, wherein the amount of the modified cellulose in the dispersion A is from 10 ppm to 5 wt.%, based on the total weight of the dispersion A. The method of claim 1, wherein the fabric substrate is a woven, knitted or non-woven fabric of natural and/or synthetic fibers. The method of claim 1, wherein the at least one polymer selected from the group consisting of polyacrylates and polybutadiene is precipitated in step c) in a water bath or at 80 to 120 ° C. temperature. A coated fabric can be obtained by the method of claims 1 to 9. A coated fabric according to claim 10, wherein the coated fabric is synthetic leather.