KR100231325B1 - Method for producing artificial leather - Google Patents

Abstract

The present invention is to impregnate the microporous polyurethane elastic body inside the three-dimensional entangled nonwoven fabric in which the microfine fiber bundle is intertwined, to prepare artificial leather, and after the polyurethane elastic body is imparted to the nonwoven fabric, the coagulating solution is added to the coagulation bath prior to the polyurethane. The present invention provides a method for producing a silky-brown artificial leather, which is characterized by spraying onto a substrate to which an adult liquid is applied and then solidifying and buffing it in a coagulation bath. The advantage of producing an improved nubuck artificial leather can be obtained.

Description

Manufacturing Method of Nubuck Algae

The present invention relates to a manufacturing method of a silk-seated artificial leather, and more particularly, in manufacturing an artificial leather by impregnating a microporous polyurethane elastic body inside a three-dimensional entangled nonwoven fabric in which an ultrafine fiber bundle is interwoven, a polyurethane elastic body in a nonwoven fabric It is characterized by spraying the coagulation liquid onto the substrate to which the polyurethane elastomer liquid is applied and then coagulating and buffing the coagulation solution before adding it to the coagulation bath. It relates to a manufacturing method of.

Artificial leather is a material that is mainly impregnated with polyurethane resin or coated with non-woven fabrics, and is similar to natural leather in terms of its structure, functionality, and flexibility, but rather has the advantages of complementing the shortcomings of natural leather. It is in the spotlight as an alternative material for.

In general, artificial leather is carded and cross-wrapped a special composite fiber that can be micronized, and then needle punched to create a three-dimensional entangled nonwoven fabric, and then filled with a microporous polyurethane elastic material therein. It is prepared by manufacturing.

Such artificial leather is roughly divided into suede artificial leather and silver artificial leather. Suede artificial leather is manufactured by buffing the leather-like sheet, raising the surface layer, dyeing and post-processing to form a wool layer on the surface. Mainly used for clothing, gloves, miscellaneous goods. Silver-type artificial leather is manufactured by forming a two-layer structure by wet or dry coating a polyurethane solution on a leather-like sheet and then embossing or laminating a polyurethane film made on a release paper having a pattern. It is mainly used for outer shell, ball outer shell, seat cover, etc.

Suede-like artificial leather is divided into velor type with long length of wool and short-seated silkworm tank according to the buffing condition. Recently, demand for silk-sewing tank with finer and more elegant appearance than the conventional suede tank has increased. Doing.

The manufacturing method of the conventional nubuck artificial leather is as follows. First, a three-dimensional entangled nonwoven fabric is manufactured by needle-punching two to five denier split or island-in-the-sea short fibers that can be micronized to form a laminated web by opening, carding and cross-lapping. Next, the density is increased by shrinking in steam or hot water, followed by filling with a water-soluble polymer such as polyvinyl alcohol (PVA) or carboxymethyl cellulose to stabilize the nonwoven fabric. Next, the dimethylformamide solution of the polyurethane elastomer is impregnated, coagulated in water and washed with water to fill the microporous polyurethane elastomer inside the nonwoven fabric. Subsequently, the temperature is raised to completely remove the filled water-soluble polymer, and then dried to remove the sea component to make the fiber fine. Next, a water-dispersible polyurethane emulsion (aqueous polyurethane) is applied to improve the smoothness of the polyurethane surface and strongly support hair growth. Finally, the final buffing machine is equipped with sandpaters, dyed, and processed into artificial leather.

In the manufacture of nubucking artificial leather, the microfine fiber bundle on the surface must be well fixed to form a short and uniform buffing length during buffing to express a luxurious nubucking appearance. As described above, in order to catch the ultrafine fiber bundle on the surface of the bubble, a method of separately applying an aqueous polyurethane to the surface after polyurethane impregnation is adopted. However, this method requires a separate aqueous polyurethane application process, which complicates the process, and in the case of general aqueous polyurethane, microcells are not formed at all. There is a problem.

Another method for catching the ultrafine fiber bundle on the bubble surface is to swell the polyurethane at the surface portion with a solvent. However, this method also has a disadvantage in that the process is cumbersome, and the polyurethane is swollen and dried, resulting in cell breakage and adhesive formation with the fiber, which results in poor touch.

Accordingly, one object of the present invention is to provide a method for producing a silky-brown artificial leather which is easy to manufacture and good in touch.

It is another object of the present invention to provide a method for producing a silk-seated artificial leather having a short, uniform and high appearance.

That is, the present invention impregnates the microporous polyurethane elastic body inside the three-dimensional entangled nonwoven fabric in which the microfine fiber bundle is intertwined, and in preparing artificial leather, the solidifying solution is added to the nonwoven fabric before the polyurethane elastic body is added to the coagulation bath. The present invention provides a method for producing a silk-yak artificial leather, which is characterized by spraying onto a substrate to which a polyurethane-based liquid is applied, and then solidifying and buffing it in a coagulation bath.

Hereinafter, the method of the present invention will be described in more detail by process.

First, the high shrinkage composite fiber usable in the present invention is a composite spinning or mixed spinning of two kinds of polymer materials capable of forming filaments in the form of sea / island. As a co-constituent, a modified polyester in which the crystallinity of the yarn is controlled to less than 35% by copolymerizing a macromolecular molecule composed of an aromatic chain in a polyethylene terephthalate backbone is used. As a copolymerization component, 2,2-bis- (4- (2 -Hydroxyethoxy) phenol) propane, 2- (4- (2-hydroxyethoxy) phenol) propane, or 2- (4- (2- (2-hydroxyethoxy) ethoxy) phenol) propane It is possible to use As the sea component, copolyester, polystyrene, polyethylene, and the like, which have different solvent soluble properties and solvents, may be used.

The composite fiber used in the present invention is advantageous in obtaining the flexibility, strength, and fidelity of bubbles when the fineness after the micronization is 0.5 denier or less, particularly 0.1 denier or less. Such a composite fiber is opened and carded by a conventional nonwoven fabric manufacturing method, a web is laminated at a desired weight, and needle punched to produce a three-dimensional entangled nonwoven fabric.

The needle punched nonwoven fabric is then shrunk by hot water, steam or dry heat or passed through a hot calender. For example, when a nylon-6 / copolymer polyester nonwoven fabric having a weight of 300 g / m2 is shrunk in hot water for 5 minutes, about 10% of area shrinkage occurs, and about 20% of area shrinkage occurs for PET / copolyester nonwoven fabrics. The apparent density of the nonwoven fabric is improved, resulting in a more compact state.

The contracted nonwoven fabric is then stabilized by padding the nonwoven fabric with a water soluble polymer solution such as polyvinyl alcohol or carboxymethyl cellulose at a concentration of 3 to 15% and drying to give 5 to 10% by weight of the fiber. This process is effective not only to stabilize the shape of the bubbles, but also to prevent the subsequent wet processing polyurethane from excessively adhering to the fiber bundle and hardening the touch.

Next, a polyurethane wet impregnation is performed on the nonwoven fabric. The polyurethane elastomers used in this process are readily dissolved in dimethylformamide (DMF) as linear polymers composed of macro glycols, polyisocyanates and low molecular weight diols having a molecular weight of 500 to 3,000. As the polyurethane elastomer used in the present invention, polyether glycol, polyester glycol, polyether polyester copolymer glycol, polycarbonate glycol, etc. may be applied as macroglycol, and as diisocyanate, usually 4,4′-diphenylmethane Diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate or 4,4'-dicyclohexyl methane diisocyanate. In the present invention, as the low molecular weight diol, 4,4'-butanediol, ethylene glycol, and the like are used, and a diamine-based chain elongation may be applied. A surfactant, a coloring pigment, an antioxidant, and the like are added to the DMF solution of the polyurethane elastomer to be used as an impregnation solution. After impregnation, the polyurethane is solidified in the non-solvent system or the non-solvent and solvent mixture system of the polyurethane, washed with hot water at 50 to 70 ° C, completely removed the water-soluble polymer filled therein, and then dried. Flexible elasticity, denseness are expressed.

The amount of polyurethane given at this time depends on the concentration of the impregnation solution, the gap between the padding roll, and the density of the nonwoven fabric to be treated. Therefore, it is necessary to adjust it to suit the required characteristics of the final bubble. It is preferable to set it as 100 parts.

In the case of general polyurethane impregnation, the surface of the forge is cleaned while controlling the content of the polyurethane by dipping the forge in the polyurethane solution and passing it through a mangle of a lower gap (for example 90% of the forge). . On the other hand, in the present invention, when the polyurethane is impregnated, the forge is immersed in the polyurethane impregnation solution to sufficiently infiltrate the surface, and the polyurethane impregnation solution is removed by scraping both sides with a coating knife so that the polyurethane is sufficiently packed to the surface. This process is called knife clearing. If the polyurethane is not scraped off with a knife after the polyurethane is applied as in the present invention, the surface becomes uneven after solidification due to the polyurethane solution that is excessively buried on the surface, and a lot of buffing occurs to remove it later.

In the present invention, by spraying water on the surface or the back side after the knife clearing before entering into the coagulation bath to solidify the surface of the polyurethane first to grab the fibers of the surface. At this time, the usable spray liquid may be surface solidified after spraying and before it is available in the coagulation bath. Water or a mixture of water and dimethylformamide (DMF) may be used, but the higher the concentration of DMF, the lower the solidification rate. It is preferable to use water or an aqueous solution of DMF with a DMF concentration of up to 20%.

In the present invention, the temperature of the spray coagulation liquid is preferably in the range of 20 to 50 ° C. If the temperature of the spray liquid is less than 20 ℃, the solidification rate is too low to solidify the surface and the inside almost at the same time, so that agglomeration of the polyurethane occurs inside it can not play a role in holding the surface fibers, on the contrary, the temperature of the spray liquid When the temperature exceeds 50 ° C., a cell is formed in a portion of the polyurethane solidified on the surface, and thus polyurethane does not hold the fiber, so it is difficult to shortly form the moor when buffing.

Next, the sea component is removed by an alkali weight loss method to perform an ultrafine fiber process. At this time, if the sea component is a copolymerized polyester, the sea component is decomposed by treating with 5 to 15% aqueous solution of caustic soda in a continuous or batch manner. If the sea component is polyethylene or polystyrene, the sea component is removed with toluene or perchloroethylene. do. For example, the sea component copolyester is completely decomposed and removed by treatment with a 5% aqueous solution of caustic soda at 95 ° C. for 20 to 50 minutes. At this time, the nonwoven fabric has some thickness reduction due to the removal of the sea component, but the shape is maintained and the elongation in the longitudinal direction due to the mechanical tension is not large.

Next, the surface of the leather-like sheet material thus obtained is buffed, but the back surface is buffed first so that the amount of grinding is uniform at the time of surface buffing so that the overall thickness is uniform. In addition, the surface buffing is to reduce the amount after grinding to less than 0.05mm, buffing a large number of two or more times, and shortly forming the wool using fine sand paper of 400 mesh or more. In the present invention, if the amount of buffing at a time is larger than the above range, it is more likely to form a long cow wool and it is difficult to access the nubuck artificial leather because the cow pad is formed unevenly. Therefore, repeated buffing in small amounts is advantageous for obtaining uniform cows and may reduce the overall loss.

Subsequently, when the fiber used is nylon-6, it is usually dyed with a metal-containing dye or millipper acid dye, and in the case of polyethylene terephthalate, it is dyed in a high-pressure rapid dyeing machine. Finally, functional preparations such as water repellents, softeners and antistatic agents are processed to produce final products.

The method of the present invention has an advantage that a silkworm-like artificial leather can be obtained better than the conventional silkworm artificial leather and the production process is shortened, thereby ultimately improving productivity. In addition, the artificial leather produced by the present invention is short and uniform in length and expresses a high-quality silkworm tank appearance.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples.

Example 1

A composite fiber staple of nylon length 2-6, fineness 3 deniers and crimp number 12-18 pieces / inch was prepared using nylon-6 65 as a island component and 35 parts of copolyester as a sea component. At this time, the number of island components was set to 36 pieces per filament. This fiber was opened and carded, and needle punched mainly with needle 40 to produce a three-dimensional entangled nonwoven fabric having a weight of 300 g / m 2, a thickness of 1.30 mm, and an apparent density of 0.230 g / cm 3. The area shrinkage rate was 10% when the nonwoven fabric was shrunk with steam at 100 캜 for 5 minutes.

Next, a 5% aqueous polyvinyl alcohol solution having an average degree of polymerization of 500 and a degree of saponification of 80 to 90% was padded with a nonwoven fabric and dried. Subsequently, after 100% elongation, a DMF solution of 12% polyether-based polyurethane having a modulus of 30 kg / cm 2 was impregnated into the nonwoven fabric, and then both sides of the fabric were scratched with a coating knife to remove the polyurethane from the surface. Subsequently, water was sprayed onto the surface to partially solidify the polyurethane on the surface, and then poured into a coagulation bath to coagulate, followed by washing with water and drying in a conventional manner. The polyurethane impregnated cloth was padded in a 13% aqueous solution of caustic soda and squeezed, followed by alkali reduction processing for 10 minutes with steam at 100 ° C, washed with water, and dried to make the fiber extremely fine. After staining the microporous fabric under normal conditions, the back surface was first buffed with sandpaper of 240 mesh to make the back evenly, and the surface was further buffed twice with 400 mm sandpaper of 0.05 mm after grinding. . Finally, a softener, an antistatic agent, and the like were treated to prepare a silkworm artificial leather and evaluated for physical properties. The results are shown in Table 1 below.

Example 2

50 parts of nylon-6 as a island component and 50 parts of copolyester as a sea component were used to prepare mixed spun staple fibers having a length of 2 inches and a fineness of 4 denier. At this time, the number of island components was 150 to 200 per filament and the microfiber after sea component extraction was 0.01 to 0.005 denier. This was carried out in the same manner as in Example 1 to prepare a nubuck artificial leather and to evaluate the physical properties and the results are shown in Table 1 together.

Comparative Example 1

Except that the impregnated polyurethane impregnation solution was passed through the mangle having a 90% gap of the thickness of the nonwoven fabric was carried out in the same manner as in Example 1 to prepare a silk-seated artificial leather and to evaluate the physical properties and the results are shown in Table 1 together It was.

Comparative Example 2

After dyeing the back surface after buffing the surface by buffing 0.1mm at a time with 240 mesh sandpaper, the same procedure as in Example 1 was carried out to prepare a silky artificial leather and evaluated the properties thereof. 1 is shown together.

Comparative Example 3

After dyeing, the surface was buffed with 400 mesh sandpaper and then buffed twice (0.05 mm) after grinding. It is shown together in Table 1 below.

TABLE 1

※ Evaluation of surface quality and appearance uniformity: 5 artificial leather experts received 1 ~ 5 points evaluation, 20 or more points are excellent (◎), 15 or more points are good (○), 10 or more points are normal (△), Less than 10 points were evaluated as defective (x).

Claims (4)

In manufacturing artificial leather by impregnating a microporous polyurethane elastomer inside a three-dimensional entangled nonwoven fabric in which microfiber bundles are entangled, a coagulant solution of 20 to 50 ° C. is added to the nonwoven fabric before adding it to a coagulation bath. A method for producing a silk-yak artificial leather, characterized in that the polyurethane liquid is sprayed on a substrate to which the liquid is applied, and then solidified and buffed in a coagulation bath. The method of claim 1, wherein the polyurethane elastic body attached to the surface of the substrate is removed with a knife coater before applying the polyurethane elastic liquid and spraying the coagulating liquid. The method of claim 1, wherein the coagulating solution is water, or a method for producing artificial silkworm leather, characterized in that water and DMF is mixed. The method of claim 1, wherein the buffing is performed by buffing the back surface first and buffing the surface by at least two times the grinding amount of 0.05 mm or less.