JP2000282372A - Production of artificial leather - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an artificial leather, making it possible to obtain the artificial leather which has a flexible touch, a rich repulsive touch and excellent mechanical strengths, by using a polyurethane dispersion not containing an organic solvent. SOLUTION: This method for producing an artificial leather comprises immersing and treating a base fabric in a polyurethane dispersion, immersing the treated base fabric in 40 to 100 deg.C hot water, and then drying the treated fabric. Therein, the polyurethane dispersion is obtained by emulsifying and dispersing a urethane prepolymer having isocyanate groups at the terminals in water in the presence of a nonionic surfactant having a HLB of 7 to 16 and then extending the chain of the dispersed urethane prepolymer with a polyamine compound having two or more amino groups and/or two or more imino groups.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing artificial leather. More specifically, the present invention relates to a method for producing artificial leather that can obtain an artificial leather having a soft feel, rich resilience, and excellent mechanical strength by using a polyurethane dispersion containing no organic solvent.

[0002]

2. Description of the Related Art Conventionally, artificial leather has been used for non-woven fabrics, woven fabrics,
It is manufactured by processing a base fabric such as a knitted fabric using polyurethane. The polyurethane used for this purpose is generally a polyurethane solution dissolved in N, N-dimethylformamide, and is impregnated by a wet method. The polyurethane layer processed by the wet method forms a porous layer, and an artificial leather tissue is formed. On the other hand,
Processing with aqueous polyurethane is also carried out, in this method,
The polyurethane dispersion containing no organic solvent is diluted with water to an appropriate concentration, and the diluted solution is used for nonwoven fabric, woven fabric,
A base fabric such as a knitted fabric is impregnated, and polyurethane is fixed to the base fabric by drying and curing to produce a tissue of artificial leather. In the production of artificial leather, the wet method using solvent-based polyurethane is excellent in the quality and texture of artificial leather, but because harmful solvents are discharged during processing and manufacturing, water pollution and air pollution are prevented. Requires a great deal of labor and cost for the recovery process. On the other hand, in the processing using the polyurethane dispersion, since no organic solvent is used, there is no need to recover the solvent, the working environment is improved, and there is no risk of water pollution and air pollution. However, when ordinary heating and drying are performed after the impregnation treatment with the polyurethane dispersion, and when the filling amount of the polyurethane into the base fabric is increased, the texture becomes coarse and hard and paper-like. Further, migration of the polyurethane to the artificial leather surface occurs, and it is difficult to fill the polyurethane with 20% by weight or more in order to suppress the fluffing of the surface. That is, while the filling amount of the wet solvent-based polyurethane is 25 to 50% by weight, it is necessary to greatly reduce the filling amount of the base cloth. As a result, the texture becomes soft, but the abrasion resistance of the obtained artificial leather and the touch on the surface become extremely poor, and when the same base cloth is used,
The strength and quality are inferior to those of the wet method using a solvent-based polyurethane. Regarding the state of adhesion to the base cloth, the wet solvent-based polyurethane adheres in a porous and non-adhesive structure to the fiber, whereas when impregnated with the polyurethane dispersion and then subjected to normal heating and drying, it is non-porous. Quality, and adheres while forming an adhesive structure with the fibers.Furthermore, the migration of the dispersion particles to the surface is unavoidable, so the flexibility of the base fabric is lost, giving a rough and hard paper-like texture. Become. In order to solve such a problem, studies have been made on a heat-sensitive gelling accelerator and a migration inhibitor, and although some effects are recognized, the effect is not always perfect, and the base cloth is particularly thick. In some cases, considerable migration is observed.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides an artificial leather using a polyurethane dispersion containing no organic solvent to obtain an artificial leather having a soft feel, a high resilience and an excellent mechanical strength. The purpose of the present invention is to provide a production method.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the urethane prepolymer having an isocyanate group at the terminal has been converted to HLB7-.
After dispersing in water using a nonionic surfactant of No. 16, a polyurethane dispersion obtained by chain extension using a polyamine compound having an amino group or an imino group is impregnated into a base fabric, and then immersed in warm water. By drying, it was found that artificial leather excellent in both mechanical strength and texture was obtained, and based on this finding, the present invention was completed. That is, the present invention provides (1) a method for producing an artificial leather by impregnating a base fabric with a polyurethane dispersion, wherein the polyurethane dispersion comprises a urethane prepolymer having an isocyanate group at a terminal, and a nonionic interface of HLB 7 to 16. A polyurethane dispersion obtained by emulsifying and dispersing in water using an activator and then chain extending using a polyamine compound having two or more amino groups and / or imino groups, wherein the base fabric is impregnated with the polyurethane dispersion. After the treatment, it is provided with a method for producing artificial leather, which is immersed in warm water at 40 to 100 ° C. and dried.
Furthermore, as a preferred embodiment of the present invention, (2) the base fabric is:
The first (1) is a non-woven fabric having a fiber thickness of 0.5 denier or less.
Item 3. The method for producing an artificial leather according to item 3, wherein the amount of the nonionic surfactant used is 0.5 to 0.5 with respect to the urethane prepolymer.
The method for producing artificial leather according to item (1), which is 10% by weight,
(4) The method for producing artificial leather according to (1), wherein the temperature of the hot water is at least 5 ° C. higher than the thermal gelation temperature of the polyurethane dispersion, and (5) the drying temperature is 100 to 16
(1) The method for producing artificial leather according to item (1), wherein the temperature is 0 ° C.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing artificial leather according to the present invention comprises:
In a method of producing an artificial leather by impregnating a base cloth with a polyurethane dispersion, the polyurethane dispersion is obtained by dispersing a urethane prepolymer having an isocyanate group at a terminal in water using a nonionic surfactant having an HLB of 7 to 16. A polyurethane dispersion obtained by chain elongation using a polyamine compound having two or more amino groups and / or imino groups. The base fabric is impregnated with the polyurethane dispersion, and then heated at 40 to 100 ° C. with hot water. Immersed in water and dried. The base fabric used in the method of the present invention is not particularly limited, and examples thereof include a nonwoven fabric, a woven fabric, and a knitted fabric. Among these, a non-woven fabric made of polyamide fiber, acrylic fiber and polyester fiber can be suitably used because artificial leather having a quality and texture close to that of natural leather can be obtained. The thickness of the fibers constituting the nonwoven fabric is preferably 0.5 denier or less. If the thickness of the fibers constituting the nonwoven fabric exceeds 0.5 denier, the texture of the artificial leather becomes coarse, the touch on the surface becomes poor, and the quality may be impaired. The urethane prepolymer having an isocyanate group at the terminal used in the method of the present invention can be obtained by reacting a polyisocyanate component with a diol component. There is no particular limitation on the polyisocyanate component used. Examples thereof include aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, and tetramethyl xylylene diisocyanate, and aliphatic diisocyanates such as hexamethylene diisocyanate. And alicyclic diisocyanates such as -bis (isocyanatomethyl) cyclohexane, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and norborane diisocyanate. One of these polyisocyanate components can be used alone, or two or more can be used in combination. Of these,
1,3-Bis (isocyanatomethyl) cyclohexane, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate and norborane diisocyanate can be particularly preferably used.

The polyol component used in the method of the present invention is not particularly limited. For example, polyethylene adipate having a molecular weight of 500 to 4,000, polyethylene propylene adipate, polybutylene adipate, polyethylene butylene adipate, polyhexamethylene adipate, polydiethylene adipate, Polyester polyol, polyoxytetra, manufactured from polyethylene terephthalate, polyethylene isophthalate, polyhexamethylene isophthalate adipate, polyethylene succinate, polybutylene succinate, polyethylene sebacate, polybutylene sebacate, poly-ε-caprolactam diol, etc. Polyether polyols such as methylene glycol and polyoxypropylene glycol, polyhexamethylene carbonate Such as polycarbonate-based polyols such as Tojioru can be mentioned. One of these polyol components can be used alone, or two or more can be used in combination. Further, if necessary, polyalkylene glycol such as polyoxyethylene glycol having a molecular weight of 400 to 4,000, polyoxyethylene propylene glycol, polyoxyethylene tetramethylene glycol, ethylene glycol, propylene glycol, 1,4-butanediol, Trimethylolpropane, glycerin, pentaerythritol, low molecular weight polyhydric alcohols such as sorbitol, ethylenediamine, diethylenetriamine, low molecular weight alkylenepolyamines such as triethylenetetramine, ethylene oxide alone or ethylene oxide and propylene oxide, butylene oxide and the like A hydrophilic component to which one or more alkylene oxides have been added can also be used as one of the polyol components.

In the method of the present invention, a urethane prepolymer having an isocyanate group at a terminal is used for preparing HLB 7-1.
Disperse in water using a nonionic surfactant of No. 6, preferably a nonionic surfactant of HLB 9-15. HLB7
Examples of the nonionic surfactants are polyoxyethylene distyryl phenyl ether type nonionic surfactants, polyoxyethylene oxypropylene distyryl phenyl ether type nonionic surfactants, and polyoxyethylene tristyryl phenyl ether type nonionic surfactants. Surfactants, polyoxyethylene oxypropylene tristyryl phenyl ether type nonionic surfactant, pluronic type nonionic surfactant and the like can be mentioned. One of these nonionic surfactants can be used alone, or two or more of them can be used in combination. HL of nonionic surfactant used
When B is less than 7, it is difficult to emulsify and disperse the urethane prepolymer, and even if the urethane prepolymer can be dispersed, its stability may be poor. Nonionic surfactant HLB
If it exceeds 16, it becomes difficult to emulsify and disperse the prepolymer, and even if dispersion is successful, the polyurethane dispersion may be eluted into the warm water when the polyurethane dispersion is impregnated into the base fabric and then immersed in warm water.
In the method of the present invention, the use amount of the nonionic surfactant is not particularly limited, but is 0.5 to the urethane prepolymer.
It is preferably from 10 to 10% by weight, more preferably from 1 to 6% by weight. If the amount of the nonionic surfactant is less than 0.5% by weight based on the urethane prepolymer, it may be difficult to obtain a stable emulsified dispersion state. If the amount of the nonionic surfactant exceeds 10% by weight based on the urethane prepolymer, the resulting polyurethane film may have poor water resistance.
In the method of the present invention, there is no particular limitation on the method of emulsifying and dispersing the urethane prepolymer in water.For example, a nonionic surfactant is added to a urethane prepolymer or an organic solvent solution of the urethane prepolymer and mixed with water, and a homomixer or the like is used. , Applying mechanical shearing force using a homogenizer or the like,
Phase inversion emulsification can be performed. The emulsification and dispersion are preferably performed at a temperature in the range of room temperature to 40 ° C. in order to minimize the reaction between the isocyanate groups in the urethane prepolymer and water and the nonionic surfactant. Also, if necessary, phosphoric acid, sodium hydrogen phosphate, p-toluenesulfonic acid,
Reaction inhibitors such as adipic acid and benzoyl chloride can be added.

In the method of the present invention, the polyamine compound having two or more amino groups and / or imino groups used for chain extension of the urethane prepolymer includes, for example, ethylenediamine, tetramethylenediamine, hexamethylenediamine, hydrazine, piperazine, isophorone Diamine, norboranediamine, diaminodiphenylmethane,
Examples include tolylenediamine, xylylenediamine, diethylenetriamine, treethylenetetramine, tetraethylenepentamine, iminobispropylamine and the like. One of these polyamine compounds can be used alone, or two or more can be used in combination. Among them, ethylenediamine, hydrazine, piperazine, isophoronediamine, norboranediamine, diethylenetriamine and iminobispropylamine can be particularly preferably used. In the method of the present invention, there is no particular limitation on the method of chain-extending a urethane prepolymer emulsified and dispersed in water using a polyamine compound.For example, a method of adding a polyamine compound to an emulsified dispersion of a urethane prepolymer to extend the chain. Alternatively, an emulsified dispersion of a urethane prepolymer can be added to a solution of a polyamine compound to extend the chain. In any method, the reaction between the urethane prepolymer and the polyamine compound is preferably performed at 20 to 40 ° C. Usually, the reaction between the urethane prepolymer and the polyamine compound is completed in 30 to 120 minutes after mixing the two. By chain extending the urethane prepolymer emulsified and dispersed in water using a polyamine compound,
A polyurethane dispersion can be obtained. In the method of the present invention, the concentration of nonvolatile polyurethane in the polyurethane impregnation bath is preferably from 5 to 50% by weight, more preferably from 10 to 40% by weight. At this time, a penetrant, an inorganic salt for promoting thermal gelation, a nonionic surfactant having a low cloud point, and the like can be added to the polyurethane impregnation bath.

In the method of the present invention, there is no particular limitation on the method of impregnating the base fabric with the polyurethane dispersion. For example, the impregnation can be performed by using a mangle or a slit mangle, or the impregnation can be performed by a coating method. Can also. There is no particular limitation on the squeezing rate and coating amount when impregnating the polyurethane dispersion, depending on the texture required for artificial leather, the type of polyurethane used, the polyurethane non-volatile content in the treatment bath, the state of the base cloth, etc. Can be selected as appropriate, but is usually preferably 50 to 400% by weight based on the weight of the base fabric. When the amount of the attached polyurethane is the same, the texture of the artificial leather obtained tends to become harder as the drawing ratio decreases. The impregnation treatment can be a pre-impregnation method of impregnating before performing the dyeing step, or can be a post-impregnation method of impregnating after the dyeing step,
In terms of the robustness and texture of the final product, artificial leather,
Pre-impregnation is more preferred. In the method of the present invention, after the base fabric is impregnated with the polyurethane dispersion,
Immerse in warm water at 40-100 ° C. The temperature of the hot water is preferably 5 ° C. or more, more preferably 15 ° C. or more, higher than the thermal gelation temperature of the impregnated polyurethane dispersion. When the difference between the temperature of hot water and the thermosensitive gelling temperature of the polyurethane dispersion is less than 5 ° C,
The polyurethane may flow into the warm water and may not be fixed to the base fabric. Even if the temperature of the hot water is significantly higher than the thermosensitive gelling temperature of the polyurethane dispersion, it does not adversely affect the adhesion of the polyurethane, but may increase the energy cost due to the high temperature of the hot water. In the method of the present invention, the drying method after fixing the polyurethane by immersion in warm water is not particularly limited, and a commonly used heating dryer can be used. After that, it is preferable to perform a dehydration step such as squeezing again using a mangle. The drying temperature can be appropriately selected according to the heat resistance of the polyurethane and the like, but is usually preferably 100 to 160 ° C. If the drying temperature is lower than 100 ° C., it takes too much time for drying, and the production efficiency may be deteriorated. If the drying temperature exceeds 160 ° C., the softening point of the polyurethane may be exceeded and the texture may become hard.

According to the method for producing artificial leather of the present invention, the polyurethane content of an artificial leather obtained by using a polyurethane dispersion is as high as that of a leather processed using a wet solvent system. No migration of polyurethane is observed, resulting in an extremely soft artificial leather. In addition, the state of adhesion between the polyurethane and the fiber can impart flexibility to the fiber in order to form a non-adhesive structure, and the resulting artificial leather has a resilient soft texture, The touch is good. Furthermore, since the content of polyurethane can be increased, not only the strength is improved in terms of physical properties such as tensile strength and abrasion strength of artificial leather, but also a moist feeling unique to polyurethane can be given to the texture, and the solvent can be provided. An artificial leather comparable to an artificial leather by a wet method using a system polyurethane can be obtained. In factories that process using wet urethane, the method of impregnating the polyurethane dispersion and then immersing it in a warm water bath is a very great advantage in that the existing equipment can be used as it is, and as a result, the environment Manufacture of artificial leather in consideration of the environment becomes possible.

[0011]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. In Examples and Comparative Examples, evaluation of artificial leather was performed by the following method. (1) Rigidity Measured according to JIS L 1096 6.19.1 A method. (2) Wear test Using a wear strength measuring machine [Yasuda Seiki Seisakusho], JIS
According to the L 1096 6.1 and 7.3C method, a test is carried out using a worn wheel CS-10 (soft cotton), a load of 1,000 g and a wear frequency of 2,000 times. After the test, the surface condition was visually evaluated on a scale of 5 from 5 (there was little difference before and after the test) to 1 (the surface was significantly worn and the base fabric itself was torn). m ² ) is measured. (3) Surface napping feeling The nap is visually evaluated in 5 steps from 5 (the same napping state as before processing) to 1 (no fluffing at all).

Production Example 1 (Production of polyurethane dispersion) Polytetramethylene glycol (average molecular weight: 1,100) 82.5 was placed in a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube. Parts by weight, polyoxyethylene oxypropylene random copolymerized glycol (average molecular weight 1,000, oxyethylene group content 70% by weight)
Take 8.7 parts by weight, 1.6 parts by weight of 1,4-butanediol, 1.9 parts by weight of trimethylolpropane, 0.001 parts by weight of dibutyltin dilaurate and 60 parts by weight of methyl ethyl ketone, mix uniformly, and then dicyclohexyl. 45.4 parts by weight of methane diisocyanate was added and reacted at 75 ° C. for 150 minutes to obtain a solution of a urethane prepolymer in methyl ethyl ketone having a free isocyanate group content of 3.0% by weight based on the nonvolatile components. After the solution was cooled to 30 ° C. or lower, 0.1 part by weight of decyl phosphate and 6 parts by weight of polyoxyethylene tristyryl phenyl ether (HLB = 15) were added, mixed uniformly, and then transferred to another container. , Water 251 using disperser blades
Parts by weight were gradually added to cause phase inversion emulsification and dispersion. A polyamine solution in which 2.9 parts by weight of piperazine and 1.1 parts by weight of diethylenetriamine were dissolved in 16.2 parts by weight of water was added, and the mixture was stirred for 90 minutes. A polyurethane dispersion was obtained. The obtained polyurethane dispersion was further desolvated at 50 ° C. under reduced pressure to obtain a nonvolatile content of 36.8% by weight.
Viscosity 35 mPa · s (BM type viscometer, No. 1 rotor, 30 rp
m.), and a stable polyurethane dispersion having an average particle size of 0.71 μm was obtained. Production Example 2 (Production of Polyurethane Dispersion) In a reaction apparatus similar to that used in Production Example 1, hydroxyl-terminated polybutylene adipate (average molecular weight: 1,000) was used.
1 part by weight, 16.9 parts by weight of polyoxyethylene oxypropylene random copolymerized glycol (average molecular weight: 1,000, oxyethylene group content: 70% by weight), 1.5 parts by weight of 1,4-butanediol, trimethylolpropane 1.
9 parts by weight, 0.001 part by weight of dibutyltin dilaurate and 60 parts by weight of methyl ethyl ketone were mixed uniformly, and then mixed with dicyclohexylmethane diisocyanate 4
0.4 parts by weight, and reacted at 75 ° C. for 300 minutes,
Free isocyanate group content with respect to nonvolatile content is 2.1
A weight percent urethane prepolymer solution in methyl ethyl ketone was obtained. After cooling the solution to 30 ° C. or lower, 0.1 part by weight of decyl phosphate, 3 parts by weight of polyoxyethylene tristyryl phenyl ether (HLB = 15) and 3 parts by weight of polyoxyethylene tristyryl phenyl ether (HLB = 10) Part, and mixed uniformly. Then, the mixture is transferred to another container.
4 parts by weight were gradually added, phase-inversion emulsification and dispersion were performed, and a polyamine solution in which 2.0 parts by weight of piperazine and 0.8 parts by weight of diethylenetriamine were dissolved in 11.3 parts of water was added.
The mixture was stirred for 90 minutes to obtain a polyurethane dispersion. The resulting polyurethane dispersion was further desolvated at 50 ° C. under reduced pressure to obtain a nonvolatile content of 37.0% by weight and a viscosity of 1%.
55mPa · s (BM type viscometer, 1 rotor, 30rp
m.) and a stable polyurethane dispersion having an average particle diameter of 0.68 μm. Reference Example 1 (Production of Polyurethane Dispersion) In a reaction apparatus similar to that used in Production Example 1, 60.0 parts by weight of polytetramethylene glycol (average molecular weight: 1,000) and 6.6 parts by weight of dimethylolbutanoic acid were used. 1.4 parts by weight of 1,4-butanediol, 1.0 part by weight of trimethylolpropane
Parts by weight, 0.005 parts by weight of dibutyltin dilaurate and 67 parts by weight of methyl ethyl ketone, and after mixing uniformly, dicyclohexylmethane diisocyanate 40.
0 part by weight was added and reacted at 75 ° C. for 250 minutes to obtain a urethane prepolymer solution of methyl ethyl ketone having a free isocyanate group content of 2.6% by weight based on the nonvolatile content. The solution was cooled to 30 ° C. or lower, and 4.5 parts by weight of triethylamine was uniformly mixed. Then, 180 parts by weight of water was gradually added to emulsify and invert the phase inversion, and 2.7 parts by weight of piperazine was added to 20 parts of water. A polyamine solution dissolved in parts by weight was added and stirred for 90 minutes to obtain a polyurethane dispersion. The obtained polyurethane dispersion is further subjected to 5
By removing the solvent at 0 ° C., a stable polyurethane dispersion having a nonvolatile content of 35.1% by weight, a viscosity of 250 mPa · s (BM type viscometer, No. 1 rotor, 30 rpm) and an average particle diameter of 0.28 μm was obtained. Obtained.

Example 1 The polyurethane dispersion obtained in Production Example 1 was
The solution was prepared so that the polyurethane content was 20% by weight.
200 g / weight of 2 denier polyester fiber
m ² of the nonwoven fabric was impregnated with a slit width 0.4mm using a slit mangle [Ita Tekko Co.]. The pickup amount at this time was about 250% by weight based on the nonwoven fabric.
Next, the non-woven fabric impregnated with the polyurethane is immersed in warm water of 80 ° C. for 1 minute, squeezed using a mangle [Daei Kagaku Seiki Seisakusho Co., Ltd.] to remove water, and furthermore, a pin tenter [UENOYAMAKIKO CO., LTD. LTD.,
LA-205] and dried at 130 ° C for 3 minutes to obtain artificial leather. The amount of polyurethane adhered to the obtained artificial leather was 49.8% by weight with respect to the base cloth, the stiffness was 93 mm in length and 86 mm in width, the surface condition after the abrasion test was 5, and the abrasion amount was 5%. It was 3 g / m ² and the surface raised feeling was 4. Observation of a scanning electron micrograph of the artificial leather revealed that the polyurethane layer was continuous from the inside to the surface of the artificial leather, formed a non-adhesive structure with the fibers, and had a thick feeling. When a physical property evaluation test was performed on the unprocessed polyester nonwoven fabric used as the base cloth, the bending resistance was 52 mm in length and 48 mm in width, the surface state after the abrasion test was 1, and the abrasion amount was 42 g.
/ M ² , and the feeling of napped surface was 5. Example 2 Using the polyurethane dispersion obtained in Production Example 2, an impregnation treatment was performed in the same manner as in Example 1 to obtain an artificial leather. The amount of polyurethane adhered to the obtained artificial leather was 49.5% by weight based on the base cloth, and the rigidity was 101 m in length.
m, the width was 92 mm, the surface condition after the abrasion test was 4, the abrasion amount was 4 g / m ² , and the napped surface was 4. Example 3 The polyurethane dispersion obtained in Production Example 1 was
A solution is prepared so that the polyurethane content is 20% by weight, and calcium chloride is further added so as to have a concentration of 3% by weight to impregnate the nonwoven fabric made of polyester fiber, and further immerse the nonwoven fabric impregnated with the polyurethane dispersion. An artificial leather was obtained in the same manner as in Example 1 except that the temperature of the hot water to be heated was 60 ° C. The polyurethane attachment amount of the obtained artificial leather was 49.9% by weight with respect to the base cloth,
The stiffness was 87 mm in length and 80 mm in width, the surface condition after the abrasion test was 4, the amount of abrasion was 5 g / m ² , and the feeling of napped surface was 5.

Comparative Example 1 Using the polyurethane dispersion obtained in Reference Example 1, an impregnation treatment was performed in the same manner as in Example 1. The amount of polyurethane attached to the nonwoven fabric after the impregnation treatment was 0.1% with respect to the base fabric.
1% by weight, the stiffness was 51 mm in length and 49 mm in width, the surface condition after the abrasion test was 1, and the abrasion amount was 45.
g / m ² , and the feeling of napped surface was 5. Comparative Example 2 The polyurethane dispersion obtained in Production Example 1 was
A solution was prepared so that the polyurethane content was 20% by weight, and a non-woven fabric made of polyester fiber was prepared in the same manner as in Example 1.
It was impregnated with a slit width of 0.4 mm using a slit mangle [Ida Iron Works Co., Ltd.]. The pickup amount at this time was about 250% by weight based on the nonwoven fabric. Next, the non-woven fabric impregnated with polyurethane was subjected to 13
Heat drying was performed at 0 ° C. for 7 minutes to obtain artificial leather. The amount of polyurethane attached to the obtained artificial leather was 4 to the base cloth.
Although it was 9.9% by weight, the rigidity was not able to be measured. The surface condition after the wear test is 5,
The abrasion amount was 2 g / m ² , and the feeling of napped surface was 1.
Observation of the scanning electron micrograph of this artificial leather revealed that most of the polyurethane was fixed as a polyurethane layer only on the surface of the artificial leather. Comparative Example 3 The polyurethane dispersion obtained in Production Example 1 was
The solution was prepared so that the polyurethane content was 10% by weight, and the same nonwoven fabric made of the same polyester fiber as in Example 1 was impregnated at a pressure of 2 kg / cm ² using a mangle. The pickup amount at this time was about 110% by weight based on the nonwoven fabric.
Next, the nonwoven fabric impregnated with the polyurethane was dried by heating at 130 ° C. for 3 minutes using a pin tenter to obtain artificial leather. The amount of polyurethane adhered to the obtained artificial leather was 10.9% by weight with respect to the base cloth, the stiffness was 96 mm in length and 90 mm in width, the surface state after the abrasion test was 3, and the abrasion amount was 3. 18 g / m ² , and the feeling of napped surface was 3. The results of Examples 1 to 3 and Comparative Examples 1 to 3,
It is shown in Table 1.

[0015]

[Table 1]

As shown in Table 1, the artificial leathers of Examples 1 to 3 produced by the method of the present invention have polyurethane firmly fixed. In addition, despite the large amount of polyurethane attached, it is flexible and has excellent wear strength, and also has good surface quality. According to the method of the present invention,
By increasing the amount of polyurethane adhered, it is possible to impart a resilient and moist texture to the artificial leather. On the other hand, in Comparative Example 1 using the polyurethane dispersion obtained in Reference Example 1, polyurethane flowed out in a warm water bath, and was almost the same as the polyester nonwoven fabric used as the base cloth. I have. Even if the polyurethane dispersion obtained in Production Example 1 was used, the artificial leather of Comparative Example 2 which was heated and dried using a pin tenter without immersing the non-woven fabric after the impregnation treatment in warm water was considered to be rigid and had a poor texture. Has become. In addition, when the amount of the attached polyurethane is reduced as in the artificial leather of Comparative Example 3, even if it is heated and dried using a pin tenter after the impregnation treatment, a certain degree of stiffness and surface raised feeling can be obtained, but the abrasion strength is low. It will be inferior.

[0017]

According to the method for producing artificial leather of the present invention,
After the base cloth is impregnated with a polyurethane dispersion containing no organic solvent, the base cloth is immersed in warm water of 40 to 100 ° C. and dried, so that not only the load on the environment is small, but also the texture is flexible and rich in resilience. It is possible to obtain an artificial leather having excellent target strength.

Claims (1)

[Claims] 1. A method for producing artificial leather by impregnating a base fabric with a polyurethane dispersion, wherein the polyurethane dispersion uses a urethane prepolymer having an isocyanate group at a terminal and a nonionic surfactant having an HLB of 7 to 16. Is emulsified and dispersed in water to obtain a polyurethane dispersion obtained by chain elongation using a polyamine compound having two or more amino groups and / or imino groups. After impregnating the base fabric with the polyurethane dispersion, A method for producing artificial leather, characterized by dipping in warm water at 40 to 100 ° C and drying.