KR20010029008A - process for preparing polyurethane/polyvinylchloride synthetic leather - Google Patents

Abstract

PURPOSE: A process for preparing artificial leather by improving peeling property of release paper and urethane resin and processability of resin is provided, which produces abrasion resistant artificial leather capable of optionally forming a pattern without limitation and relation with a release paper pattern. CONSTITUTION: This process comprises the steps of: preparing a polyurethane sol by adding a pigment and a solvent to polyurethane; preparing a PVC sol by mixing a plasticizer, a stabilizer, a filler, ceramic powder, a foaming agent and a pigment to PVC resin; preparing an intermediate product by coating the polyurethane sol on release paper, gelling, coating the PVC sol on the polyurethane resin, foaming in an oven, coating a two-component adhesive on the obtained foaming layer, removing the solvent and adhering to fabrics; and forming a pattern by pressing at 170 to 180deg.C with an embossing machine and gravure printing or surface treating.

Description

Process for preparing polyurethane / polyvinylchloride synthetic leather}

The present invention relates to a process for producing polyurethane (PU) / polyvinylchloride (PVC) artificial leather which emits far infrared rays.

In the conventional artificial leather manufacturing technology, a polyurethane resin is coated on a PU / PVC release paper having a specific shape of embossing to make an upper layer, and then PVC is coated on the urethane resin to gel the resin first, followed by foaming at a predetermined magnification. There is a direct foaming method for manufacturing artificial leather by adhering the fabric on the foam layer with an adhesive. However, the direct foaming method should use only a release pattern of a specific pattern, and since the heat resistance (melting at 200 ° C.) of the release paper coating layer is lower than the foaming temperature of the foaming resin, the release paper coating layer is melted at 200 ° C. or higher. When foaming at 240 ℃ release of the release paper coating layer on the surface of the product is difficult to work, the release paper is broken, the number of times of use is not only shortened, the cost of the PU / PVC-only release paper was expensive, there was a problem of rising costs.

In addition, when the existing urethane resin is coated on the release paper for PVC, the urethane resin is adhered to the coating layer of the PVC release paper due to the high adhesion of the urethane resin, so that the release paper and the urethane resin do not peel off.

In order to prevent the damage of the release paper due to deterioration as described above, there is a plywood method of coating polyurethane on a release paper and adhering a separately produced PVC, but for the complexity of the process of attaching an adhesive by separately manufacturing a PVC foam layer and for curing the adhesive There was a cumbersome problem of maintaining a constant temperature and humidity during curing.

In addition, in Korean Patent No. 142117, there is a method of manufacturing artificial leather by applying only a foam layer to which ceramic powder is added without gel layer and foaming the artificial leather. The surface of the artificial leather manufactured by this method has only a foam layer. Since the coating is weak and has a low scratch resistance.

Therefore, the problem of the present invention is to simplify the manufacturing process, to improve the peelability of the release paper and urethane resin, and to improve the processability of the resin by making the thermal properties such as melt behavior similar to that of PVC, regardless of the pattern of the release paper. It is to provide a method of producing a wear-resistant artificial leather that can form a pattern randomly and feels similar to natural leather.

The present invention comprises the steps of preparing a polyurethane sol by adding a pigment and a solvent to the polyurethane;

Preparing a PVC sol by mixing a PVC resin with a plasticizer, a stabilizer, a filler, a ceramic powder, a blowing agent, and a pigment, which are far infrared emitting materials;

After applying the polyurethane sol on the PVC release paper by knife coating method, the solvent is removed and gelated, and then the PVC sol is applied to the polyurethane resin with a knife coater and then gelled and foamed in an oven. Preparing an intermediate product by applying a polyurethane two-component adhesive on the resulting foam layer by secondary foaming in an oven, removing the solvent in a drying oven, and adhering the fabric. And

It maintains the surface temperature of the intermediate product at 170 ~ 180 ℃ to form a pattern by pressing with an embossing machine and provides a method for producing a polyurethane / PVC artificial leather comprising the step of gravure printing or surface treatment.

According to the present invention, the amount of the pigment used in the preparation of the polyurethane sol is 1 to 3 parts by weight (the number of additives g per 100 g of the resin), and the amount of the pigment used in the preparation of the PVC sol is 3 to 7 parts by weight. , The amount of solvent is 20 to 45 parts by weight, the amount of plasticizer is 50 to 110 parts by weight, the amount of stabilizer is 2 to 5 parts by weight, the amount of filler is 30 to 50 parts by weight, and the amount of ceramic powder is 10 to 50 parts by weight. Part, and the amount of blowing agent is 2 to 4 parts by weight.

Solvents used in the present invention include methyl ethyl ketone and dimethyl formaldehyde, the amount of which is 20 to 30 parts by weight of methyl ethyl ketone, and 5 to 15 parts by weight of dimethyl formaldehyde. Methyl ethyl ketone is the proper working viscosity at 20 to 30 parts by weight, and dimethyl formaldehyde is used to prevent the formation of pores on the surface of the product PU by rapid volatilization of methyl ethyl ketone. And when more than 15 parts by weight of resin has a disadvantage that takes a long time to completely remove the solvent.

In addition, the plasticizer used in the present invention includes dioctyl phthalate (DOP), diisodecyl phthalate (DIDP), or diisononyl phthalate (DINP), and 50 to 110 parts by weight of these are used. If the amount is less than 50 parts by weight, the viscosity is too high and the product is severely hardened, and if it exceeds 110 parts by weight, the product is too soft.

Ba-Zn-based stearate is used as the stabilizer used in the present invention, and the amount thereof is 2 to 5 parts by weight. If the amount is less than 2 parts by weight, the effect of the stabilizer is weak. If it exceeds, it acts as a stabilizer, and the remaining excess stabilizer gradually comes out of the product surface while using the product.

In addition, fillers that can be used as cost reduction and foaming nucleus in the present invention include calcium carbonate and aluminum hydroxide, and ceramic powders used for far-infrared radiation include natural jade, synthetic ceramics, ganban stone, gansumite, charcoal powder, ocher, and germanium powder. The amount of the ceramic powder used is 10 to 40 parts by weight, and the amount of the ceramic powder is determined according to the far-infrared emissivity of the ceramic itself, and the total amount of the filler and the ceramic powder used is not more than 60 parts by weight. If the total amount of the filler and the ceramic powder combined exceeds 60 resin parts, the product becomes too hard and the product properties drop sharply.

The blowing agent used in the present invention is an azo-based compound, for example, azodicarbonamide, the amount of which is used is 2 to 4 parts by weight, the amount of which is determined by the expansion ratio of the product.

In the present invention, it is preferable to use a polyurethane resin made of a polycarbonate polyol, an elastic modulus of 50 to 60 kg / cm 2, and a PVC resin having a polymerization degree of 1500 to 1700 for peelability with a release paper coating layer and elasticity similar to that of natural leather. The polyurethane sol is preferably applied in an amount of 120 to 140 g / m ² . If the coating amount is less than 120 g / m ^{2, the} polyurethane film has a weak problem.

The temperature of the drying oven is 150 ~ 160 ℃ for removing the solvent in the polyurethane and making it into a soft film. If it is less than 150 ℃, it takes a lot of time to remove the solvent. There is a disadvantage that a hole is formed in the surface of the film.

The temperature of the oven when gelling and foaming the PVC first is preferably 210 to 220 ° C. If the temperature is less than 210 ° C., the productivity decreases. If the temperature exceeds 220 ° C., the initial foaming proceeds rapidly with gelation. This falling problem occurs.

When foaming the PVC secondly, the temperature of the oven is preferably 230 to 240 ° C. If the temperature is lower than 230 ° C, the foamability is lowered. If the temperature exceeds 240 ° C, yellowing of the product surface occurs due to thermal decomposition of the PVC resin. A problem occurs.

According to the present invention, the temperature of the drying oven used to remove the solvent in the adhesive to prepare the intermediate product is preferably 90 to 110 ° C. If the temperature is less than 90 ° C., it takes a long time to remove the solvent. Too dry and the curing of the adhesive occurs a problem that the adhesive strength falls.

In order to form a pattern by pressing with an embossing machine, the surface temperature of the intermediate product must be maintained at 170 to 180 ° C. If the temperature is less than 170 ° C, the pattern of the urethane resin is not softened at the time of embossing. If exceeded, the urethane resin is completely melted and thermal decomposition of the PVC resin is started in the foam layer, which causes a problem in that the adhesion between the urethane resin and the PVC resin falls.

After the embossing process is finished, the desired pattern is printed with a printing roll of a specific pattern as needed, or the final product artificial leather is manufactured by adjusting the gloss and feel using a urethane surface treatment agent.

Hereinafter, although an Example is given and this invention is demonstrated in detail, the scope of the present invention is not limited to these Examples.

Example 1

Polyurethane sol was prepared by uniformly dispersing 20 parts by weight of methyl ethyl ketone, 5 parts by weight of dimethylformaldehyde, and 3 parts by weight of pigment in a polyurethane resin by stirring at 1000 RPM for 10 minutes at room temperature.

70 parts by weight of DOP as a plasticizer, 3 parts by weight of Ba-Zn-based stearate as stabilizer, 20 parts by weight of calcium carbonate as filler, 3 parts by weight of azo compound as foaming agent, and natural jade as ceramic powder to PVC resin (polymerization degree 1650-1700) 30 Parts by weight and 5 parts by weight of pigment were stirred at room temperature for 30 minutes with a stirrer and mixed uniformly. At this time, the stirring was started at 500 RPM and gradually stirred at a high speed up to 1500 RPM to prepare a PVC sol. In order to prevent a viscosity rise by the temperature increase by friction between PVC sol, it stirred at the speed of 1500 RPM or less.

Polyurethane sol was applied on a release paper with a knife coater at a coating amount of 120 g / m ² , and the solvent was completely volatilized in an oven at 150 ° C. to form a polyurethane upper layer, and a 0.4 mm thick PVC sol was applied on the polyurethane upper layer. After gelling and initial foaming in the primary oven at 210 ° C. and foaming in the secondary oven at 235 ° C., the two-component urethane adhesive is applied onto the PVC foam layer, and the solvent is then volatilized in a 95 ° C. drying oven. Was bonded and the lower release paper was peeled off to prepare an intermediate product.

The intermediate product obtained above was printed on a polyurethane upper layer with a urethane ink using a gravure printing machine to adjust color. Thereafter, the surface treatment was performed with a urethane-based pretreatment agent.

After the pre-processed semi-finished product is maintained at 175 ° C just before embossing, the surface urethane resin and PVC resin of the foam layer soften sufficiently, and then the embossing roll with a specific pattern is pressed onto the product surface. Was embossed.

The desired color was printed on the surface of the embossed product with a printing roll having a specific pattern, and a urethane-based surface treatment agent was used to control the gloss and the touch to emit far infrared rays, thereby producing a final artificial leather having excellent abrasion resistance and a touch similar to that of natural leather.

Example 2

Polyurethane sol was prepared in the same manner as in Example 1 except that 30 parts by weight of methyl ethyl ketone and 10 parts by weight of dimethylformaldehyde were used.

80 parts by weight of DIDP instead of 70 parts by weight of DOP as plasticizer, 2 parts by weight of Ba-Zn-based stearate, 30 parts by weight of calcium carbonate as filler, 10 parts by weight of synthetic ceramic powder (manufactured by Osan Chemical Co., Ltd. A PVC sol was prepared in the same manner as in Example 1 except that it was used.

The polyurethane sol was applied at a coating amount of 140 kg / m 2, except that the temperature of the polyurethane drying oven was 160 ° C., and the temperatures of the primary and secondary foam ovens were 220 ° C. and 240 ° C., respectively. An intermediate product was prepared in the same manner as in Example 1.

The final artificial leather was produced in the same manner as in Example 1 for the other pretreatment, embossing and post-treatment processes.

Example 3

A polyurethane sol was prepared in the same manner as in Example 1 except that 2 parts by weight of pigment and 30 parts by weight of methyl ethyl ketone were used.

In Example 1, except that 100 parts by weight of DINP as plasticizer, 4 parts by weight of Ba-Zn-based stearate, 30 parts by weight of calcium carbonate as filler, 20 parts by weight of ganbanite powder as ceramic powder, and 3 parts by weight of pigment are used. PVC sol was prepared in the same manner as.

An intermediate product was prepared in the same manner as in Example 1 except that the polyurethane sol was applied in an application amount of 130 kg / m 2 and the temperature of the adhesive drying oven was 100 ° C.

The final artificial leather was produced in the same manner as in Example 1 for the other pretreatment, embossing and post-treatment processes.

Comparative Example 1

Add a plasticizer, stabilizer, foaming agent, filler, ceramic powder, pigment, etc. to the PVC resin of high polymerization degree and mix well with a stirrer to make a PVC sol, and coated it with a thickness of 0.4 mm on a plain release paper for PVC 1, After foaming in a secondary foam oven, the reinforcing fabric was bonded with an adhesive and the release paper was peeled off to make an intermediate product. Inks and treatments were used to adjust color and gloss before embossing and embossing with an embossing roll to form a pattern on the product surface. After embossing the desired pattern was printed and the final gloss and touch was adjusted with the treatment agent.

Comparative Example 2

After the polyurethane resin on a release paper for PC / PVC with a particular pattern applied in a coating amount of 140 g / m ^2, and evaporation of the solvent in a drying oven plasticizer to PVC resin with a high polymerization degree on a urethane resin, stabilizer, blowing agent, filler, PVC sol with ceramic powder and pigments dispersed in 0.4 mm thickness, foamed in 1st and 2nd foam oven, bonded with reinforcing fabric with adhesive, peeled off the release paper, and artificial with the same surface pattern as the specific release paper pattern. Leather products were prepared.

The results of Examples and Comparative Examples 1 and 2 are shown in Tables 1 and 2.

Table 1. Comparison of General PVC Release Paper

Item Example 1 Comparative Example 1 Moldable pattern All patterns in the form of embossed rolls All patterns in the form of embossed rolls Pattern formation Embossing roll Embossing roll Surface layer Urethane Resin Layer PVC foam layer touch Soft and elastic No elasticity Release paper Private Release Paper for General PVC Private Release Paper for General PVC Abrasion Resistance (Weight Loss) 0.041 g 0.064 g

Table 2. PU / PVC Release Paper Comparison

Examples 2 and 3 Comparative Example 2 Moldable pattern All patterns in the form of embossed rolls Release paper pattern Pattern formation Embossing roll Release paper Surface layer Urethane Resin Layer Urethane Resin Layer Release paper (number of uses) Private release paper for general PVC (15 times) Patterned release paper for PU / PVC (3-4 times)

In the above examples and tables, it can be seen that the artificial leather manufactured according to the present invention is superior in the touch, the number of use of the release paper, and the wear resistance than the artificial leather manufactured by the conventional method.

Claims (4)

Preparing a polyurethane sol by adding a pigment and a solvent to the polyurethane; Preparing a PVC sol by mixing a plasticizer, a stabilizer, a filler, a ceramic powder, a blowing agent, and a pigment, which are far infrared emitting materials; After applying the polyurethane sol on the PVC release paper by knife coating method, the solvent was removed and gelled, and then the PVC sol was applied to the polyurethane resin with a knife coater and then gelled and foamed in an oven. Then, secondary foaming in an oven to apply a polyurethane two-component adhesive on the resulting foam layer, removing the solvent in a drying oven and adhering the fabric to produce an intermediate product; And Maintaining the surface temperature of the intermediate product at 170 ~ 180 ℃ to form a pattern by pressing with an embossing machine and the step of manufacturing a polyurethane / PVC artificial leather comprising gravure printing or surface treatment. The method of claim 1, wherein the amount of the pigment in the manufacturing step of the polyurethane sol is 1 to 3 parts by weight, the amount of the pigment in the manufacturing step of the PVC sol is 3 to 7 parts by weight, the amount of the solvent is 25 to 45 parts by weight The amount of plasticizer is 50 to 110 parts by weight, the amount of stabilizer is 2 to 5 parts by weight, the amount of ceramic powder is 10 to 40 parts by weight, the amount of filler is 20 to 50 parts by weight, and the ceramic powder and A method of producing artificial leather, in which the total amount of fillers is not more than 60 parts by weight and the blowing agent is 2 to 4 parts by weight. The solvent according to claim 1, wherein the solvent is methyl ethyl ketone or dimethyl formaldehyde, the plasticizer is dioctylphthalate (DOP), diisodecyl phthalate (DIDP), or diisononyl phthalate (DINP), and the stabilizing agent is Ba-Zn-based. A method of producing artificial leather wherein stearate, filler is calcium carbonate, aluminum hydroxide, ceramic is natural jade, synthetic ceramic, elvan, gansumite, charcoal powder, loess, germanium and blowing agent is an azo compound. The method of claim 1, wherein the polyurethane resin is a carbonate-based polyol using an elastic modulus of 50 ~ 60 kg / ㎠, the degree of polymerization of the PVC resin is 1500 ~ 1700, the coating amount of the polyurethane sol is 120 ~ 140 g / m ² , A method for producing artificial leather wherein the temperature of the gelling and primary foaming oven is 210 to 220 ° C, the temperature of the secondary foaming oven is 230 to 240 ° C, and the temperature of the adhesive drying oven is 90 to 110 ° C.