JP2002227078A - Artificial leather substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightweight soft suede-like artificial leather substrate which has mechanical properties capable of resisting to uses such as sport shoes and has an appearance having a special bright effect. SOLUTION: This artificial leather substrate comprises a polymer elastomer and a nonwoven fabric which is three-dimensionally interlaced with bundles comprising ultra fine fibers each having a fineness of <=0.15 dtex and a hollow portion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightweight, flexible suede having excellent appearance of color depth and darkness, having a special luminous effect in which a lighting effect is remarkable, and having excellent mechanical properties. TECHNICAL FIELD The present invention relates to a base material for a synthetic artificial leather, a lightweight and flexible silver-finished artificial leather having excellent mechanical properties, and a method for producing the same.

[0002]

2. Description of the Related Art In various fields of artificial leather, lightweight and flexible products having excellent mechanical properties are required. 2. Description of the Related Art Conventionally, it has been known that a nonwoven fabric is formed by using a multicomponent fiber having a sea-island structure in which sea components can be eluted, for example, a sea-island structure fiber in which a sea component is made of polyethylene, and an artificial leather is formed using the nonwoven fabric.
In such a sea-island structural fiber, the sea component is removed in any step until the end product is obtained, and the fiber is ultrafine to obtain an ultrafine fiber. Such products have a texture unique to microfibers and a good suede appearance, and have a certain reputation in the market. However, an increase in specific gravity due to a decrease in thickness at the time of ultrafine fiber formation is inevitable, and it does not have lightness.

[0003] Also, different kinds of fibers are mixed according to the purpose,
The formation of an entangled nonwoven fabric is a method that has been conventionally performed. Japanese Patent Publication No. 48-11925 discloses a entangled body in which two or more webs and sheets are laminated and entangled, and a method of impregnating and coagulating the entangled body with a polymer elastic solution. Although this method is leather-like and has excellent mechanical properties, it does not have good suede appearance and light weight.

Polyester and nylon hollow fibers are generally used in clothing products and the like from the viewpoints of light weight, heat retention and the like. In the field of synthetic leather and artificial leather,
JP-A-47-28104 and JP-A-50-55
No. 02 describes a lightweight and highly breathable synthetic leather using hollow fibers. Further, synthetic leather in which minute hollow particles are mixed to reduce the weight and improve the heat retaining property is disclosed in
No. 92188. As described above, techniques for using a substance having a hollow structure including fibers for synthetic leather and artificial leather are known, but these have lightness,
The appearance as suede is inadequate, and even if it has light weight and the required mechanical performance, it is insufficient in the flexibility and surface appearance that are strongly required in recent years, It did not have both.

[0005]

In the field of artificial leather, a substrate having a thickness of 0.5 to 3.0 mm is generally used. Within this thickness range, flexible products that are lighter and have excellent mechanical properties are demanded.Especially for suede-like artificial leather, excellent mechanical properties and lightweight and flexible suede feel are required. The artificial leather substrate that satisfies all of them has not been developed yet. In recent years, in each field of artificial leather, an improvement in luxuriousness has been demanded, and among them, luxurious appearance and lightness are the most important items. On the other hand, mechanical properties according to the application are also required. Particularly in artificial leather for sports, the peeling strength between the rubber sole portion and the artificial leather product and the tear strength required during exercise are the most important characteristics. It is extremely important to have both physical properties, light weight as a product, and excellent appearance.

As a measure for solving the problem, for example, a method of increasing the ratio of components to be removed by extraction or the like in a sheet made of multicomponent fibers that can be made finer by extraction or the like, such as a sea-island structure fiber sheet, can be considered. In the method, an effective weight reduction cannot be achieved due to a decrease in thickness due to a tension or a press treatment in a manufacturing process, and mechanical properties are also insufficient. Further, the method of reducing the fiber amount of the artificial leather product itself can reduce the weight, but has a problem that sufficient mechanical properties cannot be obtained. Also, in the method of using these hollow fibers as a base for artificial leather by utilizing the bulkiness of staples of hollow fibers, a certain degree of weight reduction can be achieved, but tension, press, etc. in the process after hollowing can be achieved. Since the hollow portion is pressed by the target external pressure, the thickness of the base cannot be maintained, and there is a problem that the expected weight reduction cannot be achieved. An object of the present invention is to solve such a problem, and to provide a lightweight and soft suede-like artificial leather having an extremely good appearance and excellent mechanical properties, and a light and soft silver-tone tone excellent in mechanical properties. An object of the present invention is to provide a base constituting an artificial leather.

[0007]

Means for Solving the Problems In order to achieve the above-mentioned object, the present inventors have conducted intensive studies, and as a result, 0.15
By using a nonwoven fabric that is a three-dimensionally entangled bundle of ultrafine fibers having a hollow portion that is less than or equal to decitex, the color has a deep, deep color appearance, and a special glittering effect that makes the lighting effect remarkable. It has been found that lightweight and flexible suede-like artificial leather can be produced. That is, the present invention provides an artificial leather substrate comprising a nonwoven fabric and a polymer elastic body in which a bundle of ultrafine fibers having a hollow portion is three-dimensionally entangled, wherein the ultrafine fibers have a fineness of 0.15 dtex or less, An artificial leather substrate characterized in that the hollow ratio represented by the following formula is in the range of 6 to 25%. Hollow ratio (%) = (A / B) × 100 A = Area of hollow portion in microfiber cross section B = Area of portion surrounded by outer periphery of microfiber cross section And preferably, each of the microfiber bundles is 0 .
It is an artificial leather substrate having a density of 03 to 0.15 decitex and comprising 10 to 50 ultrafine fibers having a hollow portion.

Further, the artificial leather substrate of the present invention can be manufactured by sequentially performing the following steps (1) to (4). (1) a step of producing a nonwoven fabric from a microfiber-generating fiber having a hollow portion and generating a microfiber bundle comprising microfibers having a fineness of 0.15 decitex or less; (2) a polymer elastic material; A step of impregnating the solution or dispersion to solidify the elastic polymer; (3) a step of generating a bundle of ultrafine fibers from the ultrafine fiber generating fibers; and (4) a step of forming a hollow portion in each ultrafine fiber. ,

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hollow microfiber-generating fibers (hereinafter referred to as hollow microfine fibers) capable of generating a bundle of microfine fibers having a fineness of 0.15 decitex or less and having a hollow portion used in the present invention. Abbreviated as fiber-generating fiber)
Is obtained by complex spinning three or more types of thermoplastic polymers having no compatibility. The hollow microfiber-generating fiber has a cross-sectional shape such that each island portion is a core-sheath type in a so-called sea-island type fiber, and includes a core component of the island portion, a sheath component of the island portion, and a sea component. Consisting of a kind of polymer. The core portion of the core-in-sheath portion, which is an island portion, may be located at the center of the core-in-sheath portion or may be offset from the center portion, and the shape of the core portion is within the scope of the present invention within the cross section of the core-in-sheath portion. The shape may be irregular as long as it has an inner area, or may have a geometric form such as a circle, an ellipse, a square, and a triangle. The number of core components present in one island portion is suitably one to three, but one is more preferable from the viewpoint of spinning stability. The sheath component polymer of the core-in-sheath type portion that is an island portion is a polymer that can be melt-spun and exhibits sufficient fiber properties such as strength, and has a higher melt viscosity and higher surface tension than the sea component polymer under spinning conditions. Polymers are preferred, for example, polyamide-based polymers such as 6-nylon and 66-nylon, and copolymers based on the same, polyester-based polymers such as polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate, and based on the same. Copolymers and the like are preferably used.

[0010] The sea component including the core-sheath portion, which is an island portion, is made of a thermoplastic polymer that is not compatible with the core component and the sheath component of the island portion. That is, the sea component polymer including the core-sheath portion that is the island portion has a lower melt viscosity than the core component polymer and the sheath component polymer of the island portion, The solubility and decomposability are different, and the solubility in the solvent or decomposer used for dissolving or decomposing and removing the sea component including the core-sheath portion, which is an island portion, is large. Are not substantially dissolved or decomposed and removed upon removal of the sea component polymer including the core-sheath portion which is the island portion), and the component having low compatibility with the two kinds of island component polymers constituting the core-sheath portion Is preferred. For example, polyethylene, modified polyethylene, polypropylene, polystyrene, modified polyester and the like are preferably used.

In the cross section of the hollow microfine fiber-generating fiber, a preferable sea-island area ratio of the island portion constituting the core-sheath portion and the sea portion including the island portion is in the range of 30/70 to 70/30. The sea component including the core portion, which is an island portion, is 3
If the content is less than 0%, the amount of components dissolved or decomposed and removed by a solvent or a decomposing agent is too small to exert a sufficient softening effect. If the sea component exceeds 70%, the island portion after the dissolution or decomposition and removal is used. The absolute amount of the sheath component in the core-in-sheath type portion and, finally, the island portion remaining finally becomes small, and sufficient physical properties as a leather-like sheet cannot be secured. Further, the fact that there are many components to be dissolved or decomposed and removed is inappropriate from the viewpoint of productivity.

The core component polymer of the core-sheath portion, which is the island portion of the hollow microfine fiber-generating fiber, includes a solvent or a decomposer used for dissolving or decomposing and removing the sea component including the island portion. (At the time of removing the sea component including the island portion, the core component polymer of the core-sheath type portion which is the island portion is not substantially dissolved or decomposed), and
A polymer having a different solubility or degradability from the sheath component of the core-sheath portion that forms an island portion of the sea-island structure (the sheath component polymer is not substantially dissolved or decomposed when the core component polymer of the core-sheath portion is removed). For example, a polyester copolymer that can be eluted with a dilute alkali or water, a water-soluble and thermoplastic modified polyvinyl alcohol, or the like is preferably used.

When the microfiber bundle having a hollow portion is generated from the hollow microfiber generating fiber of the present invention, only the sea component including the island portion is first dissolved or decomposed and removed, and then the core as the island portion is removed. By taking a method of dissolving or decomposing and removing the core component of the sheath-shaped portion, it is possible to maintain the thickness and prevent an increase in specific gravity. That is, in a conventionally known method of extracting sea components from a sea-island structure fiber sheet obtained by impregnating a non-woven fabric with a polymer elastic solution or dispersion and coagulating the polymer elastic, by tension or press treatment in a manufacturing process. As a result, the thickness is reduced and the weight cannot be reduced. When the sea component of the sea-island type ultrafine fiber-generating fiber is removed, in addition to the occurrence of thinning of the fiber due to the removal of the sea component, the polymer elastic body impregnated in the nonwoven fabric is swelled and softened and the tension is applied or the pressing process is performed. However, there was a problem that the thickness could not be maintained.

One of the advantages of the present invention is that the core-sheath structure is used when the sea component including the island portion, which is the core-sheath structure of the hollow microfiber-generating fiber, is removed by extraction or the like to generate the fine fibers. When the core component in the island portion remains, there is a point that the reduction in thickness due to tension in the manufacturing process or pressing can be reduced and alleviated.
Thereafter, the solvent or decomposer used for dissolving or decomposing and removing the sea component of the sea-island structure is different in solubility or decomposability, and the sheath component of the core-shell structure forming the island portion is substantially dissolved or decomposed. If the core component is removed by treating with a solvent or a decomposing agent that dissolves or decomposes the core component without leaving, the sheath component of the island portion remains, which is finer than 0.15 dtex and less than the ultrafine fiber having a hollow portion. And a lighter body can be achieved.

The core component is subjected to a hot water washing step for removing a solvent or a decomposing agent remaining in the substrate after removing the sea component including the island portion having the core-sheath structure, Preferably, it can be removed in a washing step after dyeing. For example, an ethylene unit containing 5 to 10 mol% and a degree of polymerization of 20
A water-soluble and thermoplastic modified polyvinyl alcohol having a saponification degree of 90 to 99 mol% in a range of 0 to 500 is 50 to 8
It is particularly preferable because it is easily dissolved in hot water at 0 ° C.

Further, in the ultrafine fiber having a hollow portion having a fineness of 0.15 decitex or less constituting the present invention, the hollow ratio of the fiber cross section must be in the range of 6 to 25%. If the hollow ratio is less than 6%, the effect of weight reduction is insufficient, and if it exceeds 25%, the hollow portion of the fiber cross section becomes remarkably crushed by the core removal, that is, the tension in the hollow generation step and the press treatment step. In addition, the thickness of the substrate cannot be maintained and a lightweight substrate cannot be obtained. In addition, the hollow ratio is the sea-island volume ratio of the ultrafine fiber-generating fiber, the thickness of the island component ultrafine fiber, the type of polymer constituting the ultrafine fiber having a hollow portion, since the shape retention characteristics at the time of removal of the core component is different, Combine the conditions as appropriate.

In the bundle of ultrafine fibers having a hollow portion constituting the present invention, the number of bundles of the ultrafine fibers is preferably 10 to 50, more preferably 15 to 45.
It is a book. When the number is less than 10, the depth of color becomes poor when a suede-like artificial leather is used. When the number exceeds 50, the hollow portion becomes small, so that the color depth is hardly developed.

In the ultrafine fiber having a hollow portion constituting the present invention, the average fineness is 0.15 dtex or less, and the preferable average fineness is 0.03 to 0.15 dtex. In general, nonwoven fabrics composed of fibers of thick decitex tend to easily lose fibers, and in the present invention, if the average fineness of the ultrafine fibers having hollow portions finally formed exceeds 0.15 decitex, the In this case, the peeling phenomenon of the ultrafine fibers becomes remarkable, and the flexibility of the substrate is impaired, resulting in a rough touch and a lack of aesthetic appearance of the surface as a suede tone. Also, 0.0
When less than 3 dtex, the fibers constituting the ultrafine fibers are unlikely to have a hollow structure.

When a suede type artificial leather is formed by using the artificial leather substrate of the present invention comprising a microfiber having a hollow portion, a raised surface made of the microfiber having the hollow portion is formed on the surface of the artificial leather. If the tips of the microfibers having a hollow portion are evenly trimmed in the nap-forming surface forming step, even if the dyeing is performed uniformly, the appearance of the outside of the hollow fiber and the appearance of the hollow wall will differ depending on the angle of the fluff, It has a deep color, a deep color, and a remarkable lighting effect. From the viewpoint of the appearance of such a special glittering effect, the hollow ratio is 6 to 2
Must be limited to the 5% range. If the hollow ratio is less than 6%, the special bright effect is not sufficiently exhibited because the hollow wall portion becomes difficult to see. On the other hand, when the hollow ratio exceeds 25%, the hollow portion of the fiber cross section is often crushed, giving an appearance with a lot of irritability and lacking in quality as a suede.

In the stretching treatment of the hollow microfine fiber-generating fiber used in the present invention, the drawing is carried out at a temperature not higher than the softening point of the sea component polymer including the island component, which is a core-sheath type in terms of prevention of fiber sticking at the time of drawing. The temperature is preferably 5 to 10 ° C lower than the softening temperature of the sea component polymer. Next, the hollow microfine fiber-generating fiber is made into a fiber having a fineness of 2 to 10 decitex through processing steps such as crimping, drying, and cutting.

The fibers are opened with a card and formed into a random web or a cross-wrap web through a webber;
The resulting fibrous web is laminated to the desired weight and thickness. Next, entanglement treatment is performed by a known method such as needle punching or high-speed fluid flow treatment to obtain a nonwoven fabric. For the purpose of improving the sense of unity of the product and the smoothness of the surface, it is inevitable to use a plurality of cards and wrappers to form a nonwoven fabric.

As the felt needle of the needle punch in the present invention, a well-known felt needle is used, but in order to sew the web in the thickness direction, a 1-barb needle which does not easily break the fiber is preferably used. To increase the specific gravity of the surface of the nonwoven fabric, a multi-barb needle such as 3 barbs, 6 barbs, and 9 barbs can be used. These needles may be combined depending on the purpose.

The number of punches in the needle punching step is
Depending on the shape of the needle used and the thickness of the web,
It is set in the range of 00 to 2500 punches / cm ² . In general, in the needle punching of the ultrafine fiber generating type fiber, if the needle punching conditions are too strong, the cutting or fiber cracking of the ultrafine fiber generating type fiber does not improve the entanglement, and the needle punching condition is too weak. Does not lead to a shortage of the number of fibers arranged in the thickness direction, and the entanglement does not improve. The basis weight of the entangled nonwoven fabric obtained by needle punching is 100 to
A range of 3000 g / m ² is preferred.

The needle-punched nonwoven fabric is preferably pressed in the thickness direction in order to smooth the surface and regulate the thickness. As a pressing method, conventionally known methods such as a method of passing between a plurality of heating rolls and a method of passing a preheated nonwoven fabric between cooling rolls can be used.・ Smoothness of the nonwoven fabric can be achieved by pressure bonding. In this step, an adhesive such as polyvinyl alcohol, starch or a resin emulsion may be added to the nonwoven fabric for the purpose of suppressing a change in the form of the step due to tension or pressing.

Next, the nonwoven fabric having a smooth surface is impregnated with a polymer elastic solution or dispersion and solidified into a sponge shape or a non-sponge shape. As the polymer elastic body, a resin conventionally used for producing a leather-like sheet is preferably used. That is, a polyurethane resin, a polyvinyl chloride resin, a polyacrylic acid resin, a polyamino acid resin, a silicon resin, a copolymer thereof, and a mixture thereof are preferable. These resins are sponge-like or non-sponge-like by impregnating the nonwoven fabric as an aqueous emulsion or an organic solvent solution and then coagulating by wet or dry method. In the present invention, prior to the removal of the sea component of the hollow ultrafine fiber-generating fiber, the polymer elastic body is impregnated and coagulated, thereby stabilizing the shape of the ultrafine fiber having a hollow portion and the thickness of the sheet during the process. It is preferable in terms of maintenance.

Next, the fibrous base material impregnated and coagulated with the polymer elastic solution or dispersion is coated with the polymer of the core component and the sheath component of the island portion and the non-solvent of the polymer elastic material impregnated and the solvent of the sea component polymer or The processing of dissolving or decomposing and removing the sea component with a liquid as a decomposing agent is performed to remove the core of the core-sheath type ultrafine fiber from the hollow ultrafine fiber by 0.15.
In order to make the fibers less than decitex, ultrafine fibers having a core and sheath of 0.20 decitex or less are generated. Next, a treatment for dissolving or decomposing and removing the core portion with a liquid that is a non-solvent for the sheath component polymer and the polymer elastic body and a solvent or a decomposer for the core component polymer is performed. To obtain an artificial leather substrate comprising an ultrafine fiber bundle having the following and a polymer elastic body.

When the substrate is made of suede-like artificial leather, the artificial leather substrate is sliced into a plurality of pieces in the thickness direction as necessary, and at least one surface thereof is subjected to a brushing treatment to mainly use ultrafine fibers. The fiber raised surface is formed. A known method typified by buffing with sandpaper or the like is used for forming the fiber nap surface. By the buffing, the cross section of the ultrafine fiber having the hollow portion is uniformly trimmed, and a special glittering effect which is one of the features of the present invention is obtained. Next, a suede-like artificial leather having an elegant appearance and no fluff falling off is obtained by performing a finishing treatment such as dyeing, rubbing, softening treatment, and brushing on the artificial leather substrate having the raised surface. . According to the present invention, preferred values include, for example, a density of 0.3 g / c.
m ³ or less, peel strength is 8 kg / 2.5 cm or more, a thickness of 1
A suede-like artificial leather excellent in mechanical properties and having a tear strength of 6 kg or more per mm is obtained.

The thickness of the artificial leather substrate can be arbitrarily selected according to the use and is not particularly limited, but is preferably 0.3 mm to 3 mm, particularly preferably 0.3 mm to 1 mm.
The range is 5 mm. Further, the weight ratio between the ultrafine fibers and the elastic polymer is preferably 35/65 to 65/35 by weight. If the ratio is out of this range, the balance between the fiber and the elastic polymer will be poor, and the finished suede-like artificial leather will not have a fullness or flexibility.

The density of the artificial leather substrate in the present invention is preferably 0.3 g / cm ³ or less. In each application field, the weight is a relative and sensory factor of the user, but the density of general artificial leather is 0.35 to 0.5 g / c.
m ³ , an artificial leather substrate having a density of 0.3 g / cm ³ or less, and a suede-like artificial leather obtained by finishing the substrate,
It can be said that it feels clearly lighter than the conventional artificial leather substrate and the suede-like artificial leather. According to the present invention, the density of the artificial leather substrate can be reduced to 0.3 g / cm ³ or less.

The artificial leather substrate of the present invention can also be suitably used in the field of artificial leather with silver. That is, by applying a leather-like film to the surface of the artificial leather substrate of the present invention, coating with a resin emulsion or a resin solution or a molten resin, gravure, embossing and the like as appropriate, and performing silver-finish finishing, the conventional artificial leather A silver-finished artificial leather that is as light as conventional artificial leather while having the same strength as that of conventional artificial leather can be obtained.
Known resins such as a polyurethane resin, an acrylic resin, a polyamide resin, a polyester resin, and a polyolefin resin can be used as the resin constituting the silver surface, but it is preferable to use a polyurethane resin in terms of texture. . In addition, the structure of the silver surface layer can be appropriately selected depending on the desired function, texture, etc., even if the structure is a porous structure obtained by wet coagulation of a polyurethane solution or a non-porous structure. And the thickness of the silver surface layer is 20 μm to 50 μm.
The range of 0 μm is preferred in terms of texture and smoothness.

[0031]

EXAMPLES Next, the present invention will be described specifically with reference to Examples.
The present invention is not limited to these examples. The parts and percentages in the examples relate to weight unless otherwise specified. In the following Examples and Comparative Examples,
Measurement of hollow ratio, specific gravity, mechanical properties, and other evaluations were performed according to the following methods.

[Method of Measuring Tear Strength of Artificial Leather Substrate]
A test piece of 0 cm × 4 cm in width is cut out, and a cut of 5 cm is made at the center of the short side at right angles to the side, each tongue is sandwiched between chucks, and torn at a speed of 100 mm / min by a tensile tester. The maximum tear load is determined, divided by the thickness of the test piece determined in advance, and represented by the average value of three test pieces.

[Measurement of Density] The weight per unit area (g / cm ² ) of the artificial leather substrate is divided by the thickness (cm), and this is defined as the density (g / cm ³ ). The thickness is JISL1
096.

[Sea-island ratio of sea-island composite fiber] The area ratio of the sea-island in the cross section of the composite fiber is 5% of the fiber cross section by an electron microscope.
A 00-fold enlarged photograph is taken and calculated from the average fiber diameter, the average diameter of the islands, and the number of islands. [Hollow ratio in cross section of ultrafine fiber bundle] The hollow ratio of the ultrafine fiber having a hollow portion is calculated by the following formula by taking a 500-fold enlarged photograph of the fiber cross section with an electron microscope. Hollow ratio (%) = (A / B) × 100 A = Area of hollow portion of microfiber cross section B = Area of portion surrounded by outer periphery of microfiber cross section [Average decitex of microfiber] The average decitex is calculated using an electron microscope. Take a 500-2000 times enlarged photograph of the fiber cross section at, decitex of the fiber before removing the core component ×
It is determined by the core-sheath ratio.

Example 1 From a polymer stream melted by three extruder melting systems, a core component contained 7 mol% of ethylene units in a core-sheath type portion, which is an island portion, using a multi-core type sheath spinning apparatus. A water-soluble and thermoplastic modified polyvinyl alcohol having a degree of polymerization of 300 and a saponification degree of 97 mol%, a sheath component of 6-nylon, and a sea component including the island portion is composed of a high-flowability low-density polyethylene (sea portion). / Island (core-sheath type) partial ratio = 40 /
60, and the number of islands was 16). The core / sheath ratio of the island portion was core / sheath = 20/80, and the number of core portions was one. The obtained fiber was drawn, crimped, and cut to obtain staple fibers having a cut length of 3.3 mm and a cut length of 51 mm.

The staple fibers were passed through a card, formed into a web by a cross wrapper method, and laminated. next,
980 using a felted needle with one barbed needle
Needle punching with a needle penetration density of P / cm ² and a basis weight of 45
A non-woven fabric of 0 g / m ² was obtained. After heating and drying this non-woven fabric to smooth the surface, it is impregnated with 13% polyurethane dimethylformamide (hereinafter abbreviated as DMF) solution, coagulated with a 20% DMF aqueous solution, washed with water, dried, and then heated with hot toluene. The polyethylene as a sea component was extracted and removed to obtain a substrate made of a core-sheath type ultrafine fiber bundle having a core component of modified polyvinyl alcohol and a sheath component of 6-nylon and impregnated polyurethane. Thereafter, the obtained substrate was heated at 80 ° C.
Is treated with a Wins dyeing machine for 30 minutes in a warm water to dissolve and remove the denatured polyvinyl alcohol as a core component, thereby forming a 6-nylon ultrafine fiber bundle having a hollow portion and a polyurethane having a thickness of 1.2 mm and a basis weight of 310 g /
An artificial leather substrate having an m ² and a weight ratio of fiber to polyurethane of 75/25 was obtained.

When the cross section of the ultrafine fiber having a hollow portion of this artificial leather substrate was observed with an electron microscope, the hollow ratio was found to be 18%.
The average fineness of the ultrafine fibers was 0.10 decitex, and the number of the ultrafine fibers in the fiber bundle was 16. After buffing one surface of the artificial leather substrate to adjust the thickness to 1.0 mm, the other surface is treated with an emery buffing machine to form a napped fiber surface, and further, Irgalan Br
Staining was performed at a concentration of 4% owf using own 2BLN (Chiba Geigy). The obtained suede-like artificial leather has a tear strength of 9 kg / 2.5 cm, a specific gravity of 0.28, and has both strength and lightness.
It has a special brilliant effect that is not found in conventional suede-like artificial leather, which has a deep color, a deep color, and a remarkable lighting effect.It has good appearance, texture, and touch, and has almost no fluff. Was.

Comparative Example 1 The procedure of Example 1 was repeated except that the fiber of Example 1 was replaced with a normal bicomponent sea-island fiber in which the island portions consisted of a single component of 6-nylon, and the step of removing the core component was omitted. The same operation was performed to obtain a suede-like artificial leather. This suede-like artificial leather is good in appearance, texture and touch feeling and hardly loses fluff, but has no special glittering effect as in Example 1, and has a tear strength of 9 kg / 2.5 cm, but has a high density. Was 0.39 g / cm ³ and lacked lightness.

Comparative Example 2 The same operation as in Example 1 was carried out except that the fiber of Example 1 was changed so that the ratio of the core / sheath component of the core / sheath structure, which is an island portion, was core / sheath = 5/95. A suede-like artificial leather having 4% of ultrafine fibers and having 16 ultrafine fibers in one fiber bundle was obtained. This suede-like artificial leather is good in appearance, texture and touch feeling and hardly loses fluff, but has a low hollowness, has almost no special glittering effect as in Example 1, and has a tear strength of 9 kg / 2. Although it was 0.5 cm, the density was 0.36 g / cm ³ , and it lacked lightness.

Comparative Example 3 The fiber of Example 1 was prepared by changing the ratio of the core / sheath component in the island portion to the core / sheath =
The same operation as in Example 1 was performed except that the ratio was set to 40/60,
Suede-like artificial leather having ultrafine single fibers having a hollow ratio of 32% and having 16 ultrafine fibers in the fiber bundle was obtained. This suede-like artificial leather has a tear strength of 9 kg / 2.5 cm,
The density was 0.31 g / cm ³ , and the strength and lightness were good, but the appearance was poor in suede, with a lot of irritability, probably because the hollow portion of the fiber cross-section was increased. Met.

Comparative Example 4 6-nylon was spun using a hollow fiber spinneret, and the obtained yarn was drawn, crimped and cut, and 1.0 dtex such that the hollow ratio of the fiber cross section was 20%. A staple fiber having a cut length of 51 mm was obtained. The staple fiber was passed through a card, formed into a web by a cross wrapper method, and laminated. Next, needle punching was performed using a felt needle having one barb on the needle at a needle penetration density of 980 P / cm ² to obtain a nonwoven fabric having a basis weight of 220 g / m ² . This nonwoven fabric was impregnated with a 10% polyvinyl alcohol solution at a pickup rate of 100%. Then, after heating and drying and pressing to smooth the surface, it is impregnated with a 13% polyurethane DMF solution, coagulated with a 20% DMF aqueous solution, washed with water and dried, and comprises 6-nylon hollow fibers and impregnated polyurethane. A substrate was obtained. Thereafter, the obtained substrate was
Treated with a Wins dyeing machine for 30 minutes in hot water at 0 ° C., a 1.2-mm thick artificial leather substrate made of 6-nylon hollow fibers and polyurethane, each of which is isolated by polyurethane, and having a basis weight of 315 g / m ^{2 was} prepared. Obtained. After buffing one surface of the artificial leather substrate to adjust the thickness to 1.0 mm, the other surface is treated with an emery buffing machine to form a hollow fiber napped surface, and further, Irgalan Brow.
n 2BLN (Chiba Geigy)
Stained at a concentration of% owf. The suede-like artificial leather obtained by finishing is good about lightness,
Since the fibers were not ultrafine fibers, they had poor touch feeling and had a lot of irritability in appearance, and lacked quality as suede.

[0042]

Industrial Applicability According to the present invention, an artificial leather substrate which can be used as a suede-like artificial leather having mechanical properties that can withstand applications such as sports shoes, and having a lightweight and flexible appearance having a special glittering effect is provided. can get. In addition, the surface of the artificial leather substrate obtained according to the present invention is subjected to silver finishing by combining leather-like film adhesion, resin coating, gravure, embossing, etc., so that silver coating having both lightness and mechanical strength is obtained. Toned artificial leather is obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) D06M 11/05 D06M 13/07 4L047 13/07 15/564 15/564 3/38 F-term (Reference) 3B154 AA08 AA09 AA17 AB22 BA25 BB32 BB58 BB59 BE06 BF07 BF29 BF30 DA06 DA09 DA13 DA19 4F055 AA02 AA03 BA11 BA12 DA07 DA09 EA05 EA12 EA24 EA30 FA15 GA02 HA04 4L031 AA14 AA20 AB34 BA04 A08 BA04 A08 BA42 BA48 BB05 BC02 BD15 CA21 CA36 CA41 DD01 DD11 EE07 EE08 4L047 AA23 AA27 AB02 AB07 AB08 AB09 BA03 CA05 CB10 CC01 CC16 EA04

Claims (3)

[Claims] 1. An artificial leather substrate comprising a nonwoven fabric and a polymer elastic body in which a bundle of ultrafine fibers having a hollow portion is three-dimensionally entangled, wherein the ultrafine fibers have a fineness of 0.15 dtex or less, And the hollow ratio represented by the following formula is 6 to
An artificial leather substrate characterized by being in the range of 25%. Hollow ratio (%) = (A / B) × 100 A = Area of hollow portion of microfiber cross section B = Area of portion surrounded by outer periphery of microfiber cross section 2. A bundle comprising ultrafine fibers having a hollow portion, wherein the number of bundles is 10 to 50, and each of the ultrafine fibers has a fineness of 0.03 to 0.15 decitex. Artificial leather substrate. 3. A method for producing an artificial leather substrate, comprising the steps of (1) to (4) being performed sequentially. (1) A nonwoven fabric is produced from a microfiber-generating fiber that has a hollow portion and has a fineness of 0.15 dtex or less and generates an ultrafine fiber bundle of microfibers having a hollow ratio of 6 to 25% in the hollow portion. (2) impregnating the non-woven fabric with a polymer elastic solution or dispersion to coagulate the polymer elastic; (3) generating an ultrafine fiber bundle from the ultrafine fiber generating fibers; 4) a step of generating a hollow portion in each of the ultrafine fibers;