KR960003183B1 - Method of producing artificial leather sheet - Google Patents

Abstract

The artificial leather-like sheet is produced by (a) composite spinning a nylon-6 as an island component and a copolymeric polyester as a sea component, (b) opening and carding the composite fiber, laminating it with a web, and needle punching the laminated fiber to make a three dimensional interlaced nonwoven fabric, (c) padding the nonwoven fabric with 5˜10% concn. of a water dispersible polyurethane emulsion, drying it at 100˜120deg. C, and heat-treating it at 150˜170deg. C for 1˜5min, (d) treating the fabric with 5% concn. of a sodium hydroxide solution at 95deg. C for 20˜50min, and (e) dipping the fabric into a dimethyl formamide solution of the polyurethane elastomer. The leather-like sheet has a good softness and bending property.

Description

Artificial leather seat and its manufacturing method

The present invention relates to a method for producing a leather-like sheet material having a compact structure, a flexible structure, and excellent bending characteristics.

Leather-like sheet material in which a microporous polyurethane elastic body is incorporated into a microfiber nonwoven fabric by a wet processing method is widely used as a basic material of artificial leather.

That is, dyeing and post-processing a leather-like sheet becomes a suede-type artificial leather, and wet coating and embossing a polyurethane solution or laminating a polyurethane film to a silver-type artificial leather. Silver-type artificial leather is widely applied as a substitute material for natural leather, such as sneaker outer shell, ball outer shell and seat cover. Especially, nonwoven fabric artificial leather using microfiber fiber has its structure, functionality and flexibility. It is similar to natural leather or rather has the advantage of making up for the shortcomings of natural leather.

The present invention relates to a novel method for producing leather-like sheets using microfibers and using nonwoven fabrics as bubbles. That is, the present invention changed the manufacturing method of the leather-like sheet material using the conventional microfiber, first, instead of the water-soluble polymer used to stabilize the shape of the nonwoven fabric, using a polyurethane binder that can be processed dry, and also wet impregnated nonwoven fabric It is an object of the present invention to provide a method for producing a leather-like sheet having more flexibility, excellent bending characteristics, and reduced rubber elasticity by using a polyester-based polyurethane capable of forming micropores as a resin.

Comparing the conventional manufacturing method of the leather-like sheet | seat consisting of the ultrafine fiber nonwoven fabric of 0.3 denier or less and a polyurethane elastic body with the manufacturing method of this invention is as follows.

First, referring to the conventional manufacturing method, the two to five denier split or island-like short fibers capable of microfiber can be opened, carded and cross-laminated to form a web, and then needle punched to produce a three-dimensional interwoven nonwoven fabric. Next, it is usually filled with a water-soluble polymer such as polyvinyl alcohol or carboxymethyl cellulose to stabilize the form of the nonwoven fabric, and then impregnated with a dimethylformamide solution of a polyurethane elastomer (hereinafter referred to as DMF), solidified in water, washed with water, and then inside the nonwoven fabric. Filled with polyurethane elastomer.

Next, the fiber is fined by removing the sea component under the solvent of the sea component after completely removing the water-soluble high-molecular substance filled with heating and drying.

Finally, sandpaper is used to buff the surface of the wool into a flexible leather sheet. In other words, the known manufacturing method is a non-woven fabric manufacturing process, a water-soluble polymer pretreatment process, polyurethane impregnation process, and the process of ultrafine fibers are essential, these processes are an important process to determine the quality and properties of the product.

Meanwhile, in the present invention, a polyurethane binder is treated instead of a water-soluble polymer, and a polyester-based polyurethane is used for wet impregnation processing.

Next, the reason for reaching the present invention will be described in detail.

That is, the manufacturing method of the leather sheet should be changed according to the composition of the fiber used and the characteristics of the final product required. For example, when the island-in-the-sea composite fiber made of nylon-6 or polyethylene terephthalate as the island component and polystyrene or polyethylene as the sea component is required, after filling the nonwoven fabric with the water-soluble polymer, the process of ultrafine fibers is performed first. Next, the polyurethane impregnation process may be performed or, conversely, the polyurethane impregnation process may be carried out first, and then the fiber fine process may be performed. Here, the former is called a preliminary elution method (a pole ultrafine process), and the latter is called a post elution method (a post ultrafine process).

On the other hand, in the case of a composite fiber made of copolyester with sea component, it is common to sequentially perform a water-soluble polymer pretreatment process, a polyurethane impregnation process, and an ultrafine fiber process, which corresponds to a post-dissolution method.

If it is carried out by the preliminary elution method, the treated water-soluble polymer is dissolved and removed in the elution process, in this case, the alkali weight loss process, so the form stability of the nonwoven fabric is lost, and the nonwoven fabric becomes paper-like. There is a disadvantage in that there is a lot of fear that the elongation under mechanical tension.

As a result, new pretreatment methods must be devised to stabilize the shape of nonwoven fabrics in order to adopt the first-run process. If not, the post-eluting method should be adopted. At this time, impregnated polyurethane should not be embrittled in alkali reduction processing, so a polyester-based polyurethane elastomer having excellent hydrolysis resistance should be used.

This is because the alkaline weight loss method is a process of treating 5 to 15% of caustic soda solution at 95 ° C. for 20 to 50 minutes, so that the polyester-based polyurethane is hydrolyzed in this process to deteriorate physical properties.

On the other hand, polyester-based polyurethane is used a lot in the manufacture of leather-like sheets used for shoes, but the reason is as follows.

Polyester-based polyurethane is excellent in hydrolysis resistance, and can be applied to any of the pre- and post-dissolution methods, but it has a disadvantage in that the rubber elasticity is large and micromachining is not formed during wet impregnation processing.

On the other hand, polyester-based polyurethane is poor in hydrolysis resistance, so it is not applicable to the post-eluting method, but during the wet impregnation process, 5 to 10 micron sized micropores are formed, and evenly distributed throughout the whole in a small amount, the flexibility and flexibility of the bubbles This has a good advantage and the rubber elasticity is also small.

Accordingly, the present inventors have made a thorough examination of a method for applying a polyester-based polyurethane as a preliminary elution method.As a result of stabilizing the shape of the nonwoven fabric, a small amount of the polyester-based polyurethane is dried instead of the usual water-soluble polymer pretreatment. Came to devise a way to handle it.

That is, the present invention will be briefly described as follows.

A needle punched nonwoven fabric was produced from a composite fiber staple fiber containing copolyester as a sea component, and then, instead of the usual water-soluble polymer treatment, the polyester-based polyurethane dispersion was padded into the nonwoven fabric, dried and heat-treated to give a fiber weight of 5 to 15. Stabilization of the form of nonwovens is allowed by the percentage.

When the polyester-based polyurethane dispersion is less than 5%, the amount of adhesion to the fiber entanglement is small, and the fastening force is weak, which is insufficient to stabilize the form of the nonwoven fabric. There is a problem that the thickness is reduced, when the amount exceeds 15%, the amount of adhesion to the fiber interlocking portion of the nonwoven fabric is high, there is a fear that the flexibility and flexibility of the bubble is lowered.

Next, the sea component is removed by a conventional alkali reduction process, and the fiber is subjected to a micronized step. Then, the DMF solution of the polyester-based polyurethane is impregnated, solidified in water, washed with water, and filled in about 20 to 50% by weight of the fiber. To be. Next, the surface of the bubble is buffed with sandpaper to prepare the wool, and if necessary, water repellent, antifouling, soft processing, or dyeing, it becomes a dense, soft and flexible artificial leather foam for shoes having excellent bending characteristics.

After all, the present invention is useful when using the composite fiber with the sea component as a co-polyester has two important differences compared to the conventional artificial leather manufacturing method.

First, the nonwoven fabric is pretreated with a polyester-based polyurethane binder that can be dry processed instead of a water-soluble polymer, and thus the polyurethane is attached to the intersection of the fibers to stabilize the form of the nonwoven fabric. It is not excessively stretched even by mechanical tension, and there is little fall back, so that it does not give paper-like feeling.

On the other hand, the water-soluble polymer used in the conventional manufacturing method is also removed at water washing after impregnating the polyurethane, but the polyurethane binder of the present invention is also important is not removed even after the process is completed.

Secondly, since it is possible to adopt the leaching method, it is possible to apply a polyester-based polyurethane for wet impregnation processing. In this case, the impregnated polyurethane elastomer forms numerous micropores with a diameter of 5 to 15 microns and is evenly distributed throughout the nonwoven fabric with a low polyurethane content, resulting in fine wrinkles at the time of bending of bubbles. There is a characteristic having a touch.

The present invention is described in detail by process as follows.

First, the composite fiber used in the present invention is a composite spinning or mixed spinning in the form of sea / island (sea / island) of two kinds of high-molecular material capable of forming a filament as a conventional component of nylon-6, poly Ethylene terephthalate (hereinafter referred to as PET) is used, and co-polyester, polystyrene, polyethylene, etc., which have different solvent and solvent solubility, may be used as the sea component, but co-polyester may be useful for the purpose of the present invention. have.

Because polystyrene or polyethylene is used as a sea component, toluene and perchloroethylene are used as solvents. Therefore, pretreatment is possible even when a conventional water-soluble polymer such as polyvinyl alcohol is used as a filler. This is because ester polyurethane can be applied even if the elution method is adopted.

On the other hand, the composite fiber used in the present invention is advantageous in obtaining the flexibility, strength and denseness of the bubbles when the fineness after the micronization is 0.5 denier or less, especially 0.1 denier or less. Such a composite fiber is opened and carded by a conventional nonwoven fabric manufacturing method, a web is loaded with a desired nonwoven fabric weight, and needle punched to produce a three-dimensional entangled nonwoven fabric.

Needle punching process is an important process to determine the density and appearance of nonwoven fabric. The physical properties and density are greatly influenced by the type of needle, the speed of felt and depth of immersion.

On the other hand, in the artificial leather manufacturing process, the needle punched nonwoven fabric is usually shrunk by hot water, steaming or dry heat, and the nylon-6 / copolymer polyester nonwoven fabric having a weight of 300 g / m2 is about 10% when shrinked for 5 minutes in hot water. Area shrinkage occurs, and in the case of PET / copolymer polyester nonwoven fabric, about 20% of area shrinkage occurs to improve the apparent density of the nonwoven fabric, resulting in a more compact state.

Next, polyurethane binder treatment is performed to stabilize the shape of the nonwoven fabric and to facilitate the subsequent micronization process. Suitable polyurethane-based binders for use in this process are mainly water-dispersible polyurethane emulsions. Usually, a 5-10% aqueous dispersion is padded on a nonwoven fabric, dried at 100 to 120 ° C, and then heat treated at 150 to 170 ° C for 1 to 5 minutes, whereby the polyurethane binder adheres mainly to the intersections of the fibers to fix the nonwoven fabric. Will be.

That is, when the aqueous dispersion of the polyurethane is dried and heat treated, the polyurethane chain may be polymerized linearly or crosslinked in three dimensions depending on the functional group of the isocyanate. The latter case is more effective because it is more stable in a polyurethane wet impregnation process using a dimethylformamide solvent because of its superior solvent resistance.

In this case, when a small amount of the melamine resin is added as a crosslinking agent, morphological stability may be further improved, and the addition of the softening agent may increase the flexibility of the bubbles.

In either method, the content of the attached polyurethane binder is adjusted to about 5 to 15% with respect to the fiber, and it is suitable in terms of touch and shape stability.

Next, the fiber is subjected to an ultra-fine process. When the sea component is a copolyester, 5 to 20% of an aqueous solution of caustic soda is used, and either a continuous or a batch method is possible. For example, when treated with a 5% aqueous solution of caustic soda at 95 ° C. for 20 to 50 minutes, the marine component copolymer is completely decomposed and removed, and the polyurethane binder is not affected because of its excellent alkali hydrolysis resistance. At this time, the nonwoven fabric has a slight thickness reduction by removing 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 polyurethane wet impregnation process is performed to the ultrafine nonwoven fabric bubble.

Polyurethane elastomers used in this process are linear polymers composed of macroglycols of 500 to 3,000 molecular weight, diisocyanates and low molecular weight diols and are usually readily soluble in dimethylformamide.

As the polyurethane elastomer usable in the present invention, polyether glycol, polyester glycol, polyether polyester copolymer glycol, polycarbonate glycol, etc. can be used as the macroglycol, and as the diisocyanate, usually 4,4'-diphenylmethane di Isocyanate, tolylene diisocyanate, hexamethylene diisocyanate or 4,4'-dicyclohexylmethane diisocyanate and the like, and low molecular weight diols include 4,4'-butanediol, ethylene glycol and the like.

In particular, in the present invention, by using polyester glycol as the macroglycol, the polyurethane elastomer was able to form fine pores having a size of 3 to 15 microns after wet impregnation. Bubble paper having such micropores is less elastic than the non-porous bubble paper, in particular, the bending characteristics of the bubble paper has a good advantage.

The dimethylformamide solution of the polyurethane elastomer is used as an impregnation solution by adding a surfactant, a coloring pigment, an antioxidant, and the like. After the 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., and dried to express the soft elasticity and denseness peculiar to the wet polyurethane elastomer.

In this case, the amount of polyurethane to be added 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 the required characteristics of the final bubble. It is preferable to set it as.

As described above, the leather-like sheet manufactured by the present invention is composed of a fiber component having a fineness of 0.5 to 0.001 denier and a microporous polyurethane elastomer having a size of 3 to 15 microns, and thus the structure is compact, flexible, low elasticity of rubber and flexural characteristics. It became this excellent artificial leather bubble paper. At this time, the leather sheet was 45 to 70% of the fiber component, the polyurethane component was 55 to 30% including a dry binder and a wet impregnation resin.

Hereinafter, the present invention will be described in detail with reference to Examples.

However, the present invention is not limited to the examples.

Both% and parts used in the present invention means values for weight.

Example 1

Using 65 parts of nylon-6 as a island component and 35 parts of airborne polyester as a sea component, a composite fiber staple having 3 deniers, a length of 51 mm and a crimp number of 12-18 pieces / inch was prepared.

This was opened, carded, and needle punched mainly with needle 40 to produce a three-dimensional interwoven nonwoven fabric having a weight of 450 g / m 2. When this was impregnated with a polyester-based polyurethane emulsion having a concentration of 7% and the nonwoven fabric was shrunk for 5 minutes in hot water at 95 ° C, the area shrinkage was 12%. After squeezing, the mixture was dried at 120 ° C. for 5 minutes and heat-treated at 160 ° C. for 3 minutes. At this time, the amount of the binder attached to the fiber was 8% relative to the fiber. The retaining ratio at this time was 75%, and the retaining ratio was calculated using the following equation.

Next, after padding and squeezing in an aqueous solution of caustic soda at a concentration of 15%, alkali reduction processing was continuously performed for 5 minutes with steam at 105 ° C, washed with water and dried.

Next, the mixture was impregnated with a DMF solution of a polyester polyurethane having a solid content of 14%, solidified in water, washed with water and dried in a conventional manner. At this time, the polyurethane elastomer impregnated in the bubble paper could be confirmed through an electron microscope that countless pores of 5 to 15 microns in diameter were formed.

Next, the leather sheet obtained when the surface wool was trimmed with a buffing cloth of 320 mesh sandpaper had a weight ratio of fiber to polyurethane of 60 to 40 and an apparent density of 0.36 g / m 3, which is very dense and faithful. When folded, fine wrinkles are formed and rubber elasticity is suitable as an artificial leather bubble paper for shoes.

Comparative Example 1

A nonwoven fabric was prepared in the same manner as in Example 1 and subjected to heat shrink.

However, the same procedure as in Example 1 was carried out with an aqueous solution of caustic soda at a concentration of 15% without performing the polyurethane binder treatment as in Example 1. At this time, the forge was stretched by about 8% in the longitudinal direction by the mechanical tension, while the shrinkage occurred in the width direction. In particular, after washing with repeated hydro padding and squeegeeing, the thickness of the forge was reduced by 50%.

Next, it was wet-impregnated as in Example 1 with a DMF solution of polyester-based polyurethane having a solid content of 14%. The obtained leather-like sheet had a fiber-to-polyurethane content ratio of 68:32 and an apparent density of 0.39 g / m 3, which is very dense but gives a paper-like feel and when folded, large wrinkles are formed. Giro was inadequate.

Comparative Example 2

The nonwoven fabric prepared in Example 1 was used to impart a polyurethane binder in the same manner as in Example 1, and then the sea component was removed to make the fibers extremely fine.

Next, it was impregnated with a DMF solution of a polyester-based polyurethane elastomer (using polytetramethylene glycol) having a solid content of 14%, solidified in water by a conventional method, and washed with water and dried.

The obtained leather-like sheet | seat was 60:40 weight ratio of fiber to polyurethane, and apparent density was 0.37 g / m <3>. The impregnated polyurethane elastic body was observed by electron microscopy, and no pores were formed. Unnecessary voids were formed in the inside of the paper so that the bending property of the paper was poor and the rubber-like feeling was not suitable as an artificial leather paper.

Example 2

60 parts of nylon-6 was used as a island component, and 40 parts of copolyester as a sea component was used to prepare 3.5 denier and 51 mm long-spun mixed staple fibers. A nonwoven fabric was prepared in the same manner as in Example 1, and the area shrinkage was 15% when shrinked in steam at 100 ° C. The nonwoven fabric was impregnated with a 7% aqueous dispersion-type polyurethane elastomer solution (thermosetting polyurethane), padded, dried at 110 ° C. for 3 minutes, and heat-treated at 150 ° C. for 3 minutes to make the binder adhere to 7% of the fiber. .

Next, the mixture was treated with 95% of caustic soda solution at a concentration of 5% for 25 minutes to completely remove the copolyester as a sea component, and washed with water and dried.

Next, the leather-like sheet obtained by wet impregnation of the polyester-based polyurethane as in Example 1 is a polyurethane elastomer having a myriad of pores of 58% and 5 to 15 microns in the ultra-fine fiber concentrator having a fineness of 0.01 to 0.005 denier. It became 42% of dense and flexible bubble paper for artificial leather.

Example 3

Using 60 parts of nylon-6 as a island component and 40 parts of polyethylene as a sea component, 3.6 denier and 51 mm length of mixed spun staple fibers were prepared by polymer blend spinning. This was opened, carded and needle punched to produce a three-dimensional interwoven nonwoven fabric having a weight of 500 g / m 2. It was shrunk in hot water, dried, and treated with polyurethane binder in the same manner as in Example 1.

However, by adding a small amount of melamine formaldehyde resin it was possible to further improve solvent resistance and form stability. The forge was repeatedly padded / squeezed with toluene at 60 ° C. to completely remove the polyethylene.

In the same manner as in Example 1, a polyester-based polyurethane was wet-impregnated. The amount of fiber-to-polyurethane content was 63%: 37% when buffing the surface of the obtained leather-like sheet to prepare the wool, and the apparent density was 0.38 g / m 3, which is faithful, especially for artificial leather having excellent flexibility and flexibility. It became bubble paper.

On the other hand, when using the bubble paper of this invention, when a silver layer forming process is performed by a conventional method, it became a raw material suitable for the outer surface of sports shoes.

Claims (4)

A leather-like sheet material composed of a nonwoven fabric in which synthetic fibers are entangled with a polymer elastomer, wherein the fiber entanglement part is fastened with a dry coagulation polymer elastomer binder, and the interfiber space part is made of a wet coagulation polymer elastomer. Artificial leather seat. The artificial leather seat according to claim 1, wherein the dry coagulation polymer elastomer binder amount is 5 to 15% by weight of the fiber. A method of producing an artificial leather sheet, characterized in that the dry coagulated nonwoven fabric is treated with a dry coagulated polymer elastomer as a binder, followed by heat treatment to harden the fiber, followed by microfiberization of the wet coagulated polymer elastomer. The method for producing an artificial leather sheet according to claim 3, wherein the amount of dry coagulated polymer elastomer is impregnated to 5 to 15% by weight of the fiber.