KR960001667B1 - A method of producing leather - Google Patents

Abstract

The leather-like sheet material is produced by (a) spinning composite fibers of an island component, i.e. nylon-6 or polyethylene terephthalate and a sea component, i.e. copolymeric polyester, polystyrene or polyethylene to make a nonwoven fabric, and shrinking the fabric with steam or hot water, (b) impregnating the fabric with a water-soluble polymer, (c) slicing and calendering the fabric, (d) wet impregnating a polyurethane elastomer, and removing the polymer, and (a) removing the island component, and buffing the surface of the fabric. The sheet material is useful for an artificial leather.

Description

Manufacturing method of leather sheet

The present invention relates to a method for producing a dense structured leather sheet, and in particular, to enhance the density of the nonwoven fabric of the components of the leather sheet composed of a nonwoven fabric and a polyurethane elastomer, ultimately compact structure, feeling of filling and rubber elasticity The present invention relates to a method of producing a leather-like sheet material that is smooth and has a smooth surface.

The leather-like sheets manufactured through a series of post-processing such as microporous polyurethane elastomers by the wet processing method inside the microfiber composite fiber non-woven fabric that can be micronized are widely used as the basic material of artificial leather.

In other words, suede-like artificial leather having a fiber wool layer formed on the surface of leather-like sheets is applied to miscellaneous goods such as gloves, wallets, etc., and a polyurethane silver layer is formed on the surface of leather-like sheets. It is well known that the upper artificial artificial leather is widely used as an alternative material for natural leather, such as the outer cover of sneakers, the ball shell, and the seat cover.

However, the artificial leather according to the conventional manufacturing method has yet to meet the dense structure, high physical properties and beautiful appearance of the natural leather, and many studies for improvement thereof have been conducted.

Many of the shortcomings of artificial leather can be attributed to the low density and low degree of fiber entanglement of the components.

In other words, the density of the leather sheet itself can be increased by increasing the filling amount of the polyurethane elastic body, but in this case, the rubber elasticity of the urethane elastic body gives the defect that the feel of the leather sheet is ruffer-like. have.

After all, the density of the fiber component must be increased to obtain a leather-like sheet having compactness and good physical properties.

Looking at the conventional methods for solving such a problem, Japanese Laid-Open Patent Publication No. 63-28974 discloses that a non-woven fabric using island-in-the-sea microfine fibers is opened with a heat press at a temperature lower than 10 ° C. below the softening temperature of the sea component. A method for producing a high density fiber sheet is proposed.

However, this method only has the effect of reducing the thickness of the nonwoven fabric sheet, but has the drawback of giving a paper-like feel of the leathery sheet and deteriorating wrinkle properties.

In addition, Japanese Patent Laid-Open No. 61-3906 describes a method for densifying low weight nonwoven fabrics.

In other words, when needle punching in a state in which the silicone surfactant is attached to the surface of the fiber in the amount of about 0.01 to 0.5% by weight, the density of the nonwoven fabric is very high (0.15 to 0.25 / cm 3) and the surface is smoothed.

However, there is a problem that the total number of punches per unit area must be considerably higher than that of the conventional method in order to manufacture a high density nonwoven fabric by this method.

In general, heavier nonwoven fabrics are advantageous for higher density than low-weight nonwoven fabrics because the thicker the thickness, the easier the three-dimensional arrangement of the fibers.

Using this fact, Japanese Patent Publication No. 59-47069 proposes a method of preparing a nonwoven fabric thicker than a desired sheet, then imparting a water-soluble polymer material, impregnating polyurethane, and then slicing as usual. Doing. However, this method alone is difficult to obtain a sufficient high-density nonwoven fabric, and on the other hand, due to the thickness of the felt, there is a disadvantage of poor post-processability, such as sea component extraction, polyurethane impregnation.

Therefore, the present inventors carefully examined the characteristics of the composite fiber to be applied to the leather-like sheet, and completed the present invention employing the following methods.

First, the combination of high-potential shrinkage and low modulus composite fibers with conventional composite fibers could improve nonwoven fabric density and three-dimensional entanglement.

Secondly, the unit weight of the nonwoven fabric was designed to twice the required weight, but the slicing process was performed before these processes to facilitate sea extraction and polyurethane impregnation processing.

Third, heat-setting with a heat press after slicing provided a smooth surface with improved density.

That is, an object of the present invention is to provide a method for organically combining a series of manufacturing methods as described above to produce a leather-like sheet having a compact structure, a feeling of filling, and rubber elasticity.

Hereinafter, the present invention will be described in detail.

The present invention is to prepare a nonwoven fabric using two or more kinds of composite fibers, and the second step of stabilizing the shape of the nonwoven fabric by impregnating a nonwoven fabric with a water-soluble polymer material in the first step of shrinking by steam or hot water, and srei in the thickness direction 3rd process of calendering and calendering with heat-fixing process, 4th process of wet impregnation of polyurethane elastic body and removal of water-soluble polymer material, and miniaturization of fiber by removing sea component which is fibrillated body, and buffing the surface It is a method characterized by combining the fifth step of trimming.

The composite fiber used in the first step of the present invention is a composite spinning of two kinds of high molecular materials capable of forming filaments in the form of sea / degree, which is usually nylon-6 and polyethylene terephthalate (hereinafter referred to as PET). And the like, and co-polyesters having different solvent soluble properties and polystyrenes (hereinafter referred to as PST) and polyethylene (hereinafter referred to as PE) are used as sea components.

In particular, when the density of the nonwoven fabric is to be used for the outer skin of a shoe, nylon-6 is used as a coating component, and copolyester or polyethylene as a sea component is suitable for yarn production and ease of processing.

In general, the higher the modulus and the more rigid the fiber, the greater the bulk density (bulk) in the overall tends to be lower density, while the lower the modulus and the more flexible fiber tends to increase the density, but the three-dimensional entanglement tends to be lower.

Therefore, in the second step of the present invention, as a result of careful examination of the mechanical properties of these fibers and their effect on the density of the nonwoven fabric, it is possible to use a composite fiber having a low modulus and a high latent shrinkage ratio for the conventional composite fiber. It was confirmed that it is effective in increasing the density and maintaining physical properties.

In addition, thickening the unit weight of the nonwoven fabric to twice the required weight could significantly increase the apparent density of the nonwoven fabric.

For example, when designing at 250g / m2, the maximum density was 0.18g / cm3, but when designing at 500g / m2 under the same conditions, the maximum density could be increased to 0.25g / cm3.

On the other hand, in the third step of the present invention, the nonwoven fabric having a stable shape is sliced in the thickness direction and heat-set by a heat press having a surface temperature of 100 to 180 ° C. to increase the density of the nonwoven fabric by about 10 to 30%. A very smooth nonwoven was obtained.

In addition, in the present invention, by performing the third step ahead of the fourth and fifth steps, the impregnation of the polyurethane elastic body can be facilitated, and the wet high speed can be enhanced, and the extraction of the sea component is easy, so that the continuous extraction method There was an advantage to apply.

On the other hand, the order of the fourth step and the fifth step in the present invention depends on the components of the composite fiber to be used.

For example, when the copolyester is used as a sea component, an alkali reduction process is generally applied to remove the copolyester, thereby limiting the type of polyurethane elastomer that can be applied in the fourth step.

In other words, the polyester-based polyurethane may be removed by alkali in the sea component extraction process.

On the other hand, when the fifth process is first processed, the water-soluble polymer is removed together with the sea component extraction, so that the morphological stability of the nonwoven fabric is weakened, and there is a fear that the sheet is stretched in the longitudinal direction under tension during the process. It gives a paper-like feel and there is a fear that the wrinkle property is worse.

The present invention will be described in more detail by raw materials and processes.

The composite fibers used in the present invention can be any of the composite fibers spun by the so-called polymer inter-array fiber manufacturing method and the composite fibers produced by the so-called blending spinning method.

However, when the final use of the leather-like sheet described in the present invention as a foam for shoes, nylon-6 or PET is suitable as a fiber component, and the sea component should be well selected to increase the density of the nonwoven fabric.

For example, fibers mixed with nylon as a island component and PE as a sea component are advantageous in obtaining a high-density nonwoven fabric having mechanical properties, in particular, modulus of the fiber, compared to a fiber having a sea component as a copolyester.

In addition, in the case of fibers having the same component, the thinner the fineness of the fiber, the higher the density of the nonwoven fabric tends to be. In general, when the denier is 1.0 denier or less, the carding property alone is not well applied.

However, when two kinds of fibers having different fineness are mixed, the density tends to be somewhat higher.

As a result of consideration of these matters, the combination of islands / sea components usable in the present invention is nylon-6 / PE, nylon-6 / PST, nylon-6 / copolymer polyester (referred to as CO-PET), nylon-6 / CO-PST, Nylon-6 / CO-PE, PET / PE, PET / PST, PET / CO-PET, PET / CO-PST, PET / CO-PE, CO-PET / PE, CO-PET / PST, CO-PET / CO-PET, CO-PET / CO-PST and CO-PET / CO-PE, and more than two types can be selected among them, but in order to finish the extraction of sea ingredients in one process in the post-processing process, It is necessary to select two or more kinds of fibers having the same powder.

Here, the copolyester is different in composition for seaweed component and seaweed component. For the seaweed component, it is selected from the range that does not embrittle physical properties and solvent resistance, and the seaweed component has a composition for facilitating alkali reduction extractability. It should be considered first.

In addition, the copolymerized polyethylene (CO / PE) and copolymerized polystyrene (CO-PST) is meant to copolymerize two or more monomers, it is also applicable to blending two or more polymers or oligomers.

These sea components are readily soluble in chlorochloroethylene and toluene, so they can easily be removed by repeated padding and squeezing of the nonwoven fabric.

Meanwhile, in the present invention, a composite fiber to be mixed with a conventional composite fiber is a fiber having a high non-shrinkage rate and a low modulus due to different components thereof, and is produced by copolymerizing a high shrinkage component or by low temperature, low magnification stretching and low temperature heat treatment after spinning. One fiber is a high shrinkage low modulus composite fiber having a boiling shrinkage of about 20% to 30% and a modulus of about 250 g / m 2.

The composite fiber used in the present invention is advantageous in obtaining the flexibility, strength, denseness and the like of bubbles when the fineness after the micronization is 0.5 denier or less, particularly 0.1 denier or less. The two or more such composite fibers are opened and carded by a conventional nonwoven fabric manufacturing method, and the web is loaded with a desired nonwoven fabric weight and needle punched to produce a nonwoven fabric.

The needle punching process is an important process for determining the density and quality of the nonwoven fabric. The physical properties and density are largely affected by the needle type, the speed of the felt, and the depth of immersion.

In addition, the total needle punching density is increased, but the density of the nonwoven fabric is increased, but at a certain limit, rather than cutting the fiber will have an adverse effect, but in the present invention 1,000 to 2500 times / cm 2 was suitable.

Conventional nonwoven fabrics shrink by hot water steaming or dry air, and the shrinkage process is essential in an artificial leather manufacturing process.

When the nonwoven fabric made of a conventional composite fiber alone was shrunk in hot water at 98 ° C. for 5 minutes, the shrinkage rate was different depending on the type of island component and sea component.

For example, a nonwoven fabric of nylon-6 / CO-PET having a weight of 300 g / m 2 had an area shrinkage of 10% while PET / CO-PET was high at 22% under the same conditions.

In addition, highly shrinkable composite fibers, such as CO-PET / CO-PET nonwovens, which can be used in the present invention, showed a much higher shrinkage of 44%.

However, a nonwoven fabric made of a highly shrinkable composite fiber alone is difficult to be used alone due to poor physical properties after processing, and sometimes entanglement by needle punching is also poor, so it is effective to use it in combination with ordinary composite fibers.

In order to facilitate slicing the nonwoven fabric thus prepared in the third step, the water-soluble polymer is padded and dried to stabilize the shape.

That is, in the second step, the nonwoven fabric is impregnated with an aqueous solution of a water-soluble polymer material having a concentration of 5 to 20%, padded by 100% by weight of the nonwoven fabric, and then squeezed and dried again to form a fiber surface, fibers, and fibers. Allow the resin to fill the intersection.

At this time, the resin conjugate of the water-soluble polymer material used is selected from polyvinyl alcohol and carboxymethyl cellulose or a derivative of starch or starch. Among these resin conjugates, a resin conjugate should be selected that can be easily dissolved and removed during the next dehydration process.

Next, in the third step, the nonwoven fabric having a stable shape is divided into two thicknesses with a slicing machine and heat-set each sliced nonwoven fabric with a heat press equipped with a heating roll to make the surface of the nonwoven fabric smooth and have a density of 10. ~ 30% increase. At this time, care should be taken because if the temperature of the roll surface is too high or the roll pressure is too high, the nonwoven fabric becomes like paper.

In particular, in order to prevent the density of only the surface of the nonwoven fabric from increasing, it is effective to calender after preheating the entire nonwoven fabric to 100 to 150 ° C. before heat-setting to soften it.

Polyurethane elastomers used in the fourth process are linear polymers composed of macroglycol, diisocyanate and low molecular weight diols having a molecular weight of 500 to 3,000 and are easily dissolved in dimethylformamide.

Polyurethane elastomer that can be used in the present invention is applicable to the polyglycol, polyester glycol, polyether, polyester copolymer glycol, polycarbonate glycol, etc. as the macroglycol, and isocyanate is usually 4, 4'- diphenylmethane di Isocyanate, tolylene diisocyanate, hexamethylene diisocyanate or 4, 4'-disaclohexylmethane diisocyanate, and the like. As the low molecular weight diol, 1, 4-butanediol, ethylene glycol and the like are possible.

In particular, the use of low molecular weight diamines in place of low molecular weight diols can enhance the mechanical and thermal properties of polyurethane elastomers.

The dimethylformamide solution of the polyurethane elastomer is added with a surfactant and a coloring pigment and 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, and the water-soluble polymer material as a filler is dissolved in hot water at about 95 ° C to remove the unique elasticity and drape characteristic of the wet polyurethane elastomer. Sex is expressed.

The amount of polyurethane given to the nonwoven fabric depends on the concentration of the impregnation solution, the gap between the padding rolls, 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 70%.

Next, the fifth fixed sea component is extracted by using 5 to 20% caustic soda solution when the sea component is a copolyester, and can be either continuous or batch method. In case of polyethylene or polystyrene, perchlorethylene, toluene, etc. It can be easily dissolved and removed by padding / squeezing the nonwoven fabric several times with solvent.

As described above, the leather-like sheet produced 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, and has a structure having a dense structure of artificial leather having a density of 0.35 g / cm 3 or more.

However, in order to evenly arrange the surface, it is necessary to buff several times with a buffing machine equipped with sand paper.

After the sea component is extracted, the leather sheet has 50 to 75% of the fiber component and 25 to 50% of the polyurethane component, and the content of the fiber component greatly contributes to the improvement of the density. Relaxed.

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

Both% and parts mean values for weight.

Example 1

A composite fiber staple having a length of 51 denier and 51 mm was prepared using 70 parts of polyethylene terephthalate as a sea component and 30 parts of copolyester as a sea component. The fineness after sea component extraction was 0.1 denier (boiling shrinkage: 8%).

A composite fiber staple fiber with a fineness of 4 deniers and a length of 51 mm was prepared from 70 parts of highly shrinkable copolymer polyester with 30 parts of copolyester with different composition and composition, and the fineness after sea component extraction was 0.14 denier. (20% non-shrinkage).

Two kinds of composite fibers were mixed and carded at 50 to 50% by weight, and needle punched with needle 40 to produce a three-dimensional interwoven nonwoven fabric having a weight of 900 g / m 2.

When the nonwoven fabric was shrunk in hot water at 95 ° C. for 5 minutes, the area shrinkage was 33% and the apparent density of the nonwoven fabric was 0.33 g / cm 3.

The nonwoven fabric was treated with 5% polyvinyl alcohol aqueous solution to obtain 7% solids relative to the weight of the fiber, resulting in a nonwoven fabric having a density of 0.38 g / cm 3, divided into two thicknesses with a slicing machine, and then heated at a surface temperature of 150 ° C. It was calendered with a press.

Next, a dimethylformamide solution of polyether polyurethane having a solid content of 12% was padded, squeezed to 80% of the thickness of the nonwoven fabric, and coagulated in water.

After washing with warm water at 50-60 ° C., the temperature was again raised, and polyvinyl alcohol binder, which is a water-soluble polymer, was completely removed from hot water at 98 ° C.

Next, the mixture was treated with 5-7% caustic soda solution at 95 ° C. for 10 minutes to completely remove the copolyester as a sea component.

In this step, the reduction ratio of polyester as an island component was less than 7%. Next, the buffing with sander paper buffed the surface and the back to shorten the fur.

The obtained leather-like sheet had a fiber-to-polyurethane ratio of 65:35 and an apparent density of 0.42 g / cm 3, which was very dense, faithful, good physical properties, and suitable as an artificial leather foam.

Example 2

Using 75 parts of polyethylene terephthalate as a island component and 25 parts of copolyester as a sea component, a composite fiber staple fiber of 3 denier and length of 51 mm was prepared by a conventional method.

That is, the draw ratio of the tow after spinning was 3.2 and the heat treatment temperature for heat setting of the crimp was 150 ° C.

In order to produce a composite fiber having a high latent shrinkage ratio, the composite fiber had a draw ratio of 2.0 and a heat treatment temperature of crimp.

The composite fiber thus obtained showed lower strength and modulus and a higher elongation of 15% than the composite fiber prepared by a conventional method.

The above two kinds of composite fibers were blended 50 to 50 to prepare a nonwoven fabric as in Example 1.

The area shrinkage in thermal contraction was 30%, and when processed as in Example 1, the ratio of fiber to polyurethane was 62 to 38, and the apparent density of the obtained leather sheet was 0.40 g / cm 3, which was very dense and faithful. It became the material for leather.

Comparative Example 1

Using 70 parts of polyethylene terephthalate as a component and 30 parts of copolyester as a sea component, a three-denier, 51 mm long composite fiber staple was prepared in the same manner as in Example 1.

That is, the elongation ratio of the tow after spinning was 3.2 and the heat setting temperature of the crimp was 150 ° C. When the needle punched nonwoven fabric having a weight of 900 g / m 2 was prepared using the above composite fiber and shrinked in hot water, the area shrinkage was 15%, and when processed in the same manner as in Example 1, the ratio of fiber to polyurethane was 60 to 40. The apparent density of the leather-like sheet was 0.34 g / cm 2, which resulted in a lack of fidelity than that of the method of Examples 1 and 2, and at the same time, a volume of polyurethane, which was not suitable for artificial leather.

Comparative Example 2

A needle punched nonwoven fabric having a weight of 450 g / cm 2 was prepared using the same composite fiber as in Comparative Example 1.

The apparent density after shrinking the nonwoven fabric in hot water was 0.25 g / cm 3, and treated with 5% polyvinyl alcohol solution to give 6% by weight of the fiber, followed by calendering to give a density of 0.28 g / cm 3.

In the same manner as in Example 1 below, the polyurethane was impregnated, the sea component was extracted, and slicing was not performed.

The obtained leather-like sheet | seat had a low apparent density of 0.32 g / cm <3> and the weight ratio of fiber to polyurethane was 55 to 45.

The leather-like sheet material by this method was not sufficiently relaxed in rubber elasticity and lacked fidelity, making it unsuitable as an air bubble for artificial leather.

Example 3

A composite fiber staple of 3.5 denier and 51 mm length was prepared by mixing spinning method with 65 parts of nylon-6 and 35 parts of polyethylene as sea component. The fineness distribution of the island components after sea component extraction was 0.005 to 0.001 denier (boiling shrinkage ratio). : 10%). The composite fiber staple fiber of 3 denier and 51mm length was prepared by mixed spinning method with 70 parts of highly shrinkable copolyester polyester and 30 parts of polyethylene as sea component. The fineness of the island component fibrils after sea component extraction ranged from 0.01 to 0.003 denier. It was. (Boiling shrinkage: 30%).

When the two composite fibers were mixed at a weight ratio of 60 to 40 to prepare a needle punched nonwoven fabric having a weight of 1,000 g / m 2 and shrinked in hot water, the area shrinkage was 25% and the apparent density was 0.36 g / cm 3.

Polyvinyl alcohol was charged and calendered to 7% by weight of the nonwoven fabric.

After dividing the thickness with a slicing machine, the mixture was padded with a dimethylformamide solution of 12% of a polyester-based polyurethane, solidified in water, washed with water in the usual manner, and the polyvinyl alcohol filler was removed.

Next, after removing the sea component polyethylene completely with a perchloroethylene solvent, the surface wool was trimmed with a buffing machine.

The obtained leather-like sheet had a weight ratio of fiber to polyurethane of 66 to 34 and an apparent density of 0.40 g / cm 3, resulting in a compact and faithful artificial air bubbles. The leather-like sheet material by this method was particularly excellent in flexibility, physical properties and smooth surface.

Claims (4)

In the manufacturing method of the leather-like sheet material which is filled with a water-soluble polymer material in a nonwoven fabric and then wet treated with a polyurethane elastomer, followed by slicing and miniaturization, two kinds of highly shrinkable composite fiber and general composite fiber are used. To produce a nonwoven fabric, slicing before impregnating a polyurethane elastomer, and heat-setting after slicing. According to claim 1, wherein the two types of composite fibers are island-in-the-sea composite fibers, high shrinkage composite fibers having a boiling shrinkage of 20 to 30%, general composite fibers having a boiling shrinkage of 8 to 10% Method for producing a leather-like sheet material, characterized in that. The method for producing a leather-like sheet material according to claim 1, wherein the mixing ratio of the highly shrinkable composite fiber to the conventional composite fiber is 20 to 80% versus 80 to 20%. 4. The method according to claim 3, wherein the ratio of the fiber component of the leather sheet material to the polyurethane elastomer is 50 to 75% by weight to 50 to 25% by weight.