JPH03161576A - Production of nubuck-tone artificial leather - Google Patents

Abstract

PURPOSE:To obtain the subject artificial leather by generating ultrathin fiber in surface layer part of nonwoven cloth comprising conjugate fiber able to be made to ultrathin fiber having specific range of apparent fiber density and porosity in the surface layer part, coagulating with applying polymeric elastomer and making conjugate fiber in inner layer part to ultrathin fiber. CONSTITUTION:Web composed of conjugate fiber able to be made to ultrathin fiber of <=0.1d is subjected to needle punch to obtain nonwoven cloth having >=0.30g/cm<3>, especially >=0.35g/cm<3> apparent fiber density of densely interlaced surface layer part and <=70% porosity. Conjugate fiber existing in surface layer part of the nonwoven cloth is made to ultrathin fiber of <=0.1d and formed to dense and short nap-like, then <=15wt.% polymeric elastomer is applied, thus said elastomer is solidified by wet or dry method and residual conjugate fiber mainly constituting inner layer part of said nonwoven cloth is made to ultrathin fiber to afford nubuck-tone artificial leather having soft, dense and short nap with excellent feeling.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a novel artificial leather with nubuck texture.

[Prior Art] Conventionally, the method for producing nubuck-like artificial leather, which is characterized by extremely dense and short naps, involves applying polymer to a sheet of woven, knitted or non-woven fabric, similar to suede-like artificial leather. After applying resin such as elastic body, grind the surface layer,
Generally, methods for obtaining naps by expressing them have been attempted.

In this method, especially for sheets with short naps, the amount of resin such as polymeric elastomer applied may be simply increased, or the resin may be partially applied by coating the sheet surface where chips occur. By unevenly distributing a large amount of fibers, the fibers constituting the sheet can be more constrained and the resistance during grinding can be increased. However, these methods require a large amount of resin such as an elastic polymer, and the resin Since the direct adhesion between the fibers and the fibers tends to form, there is a disadvantage that the texture of the sheet becomes hard.

In addition, methods that do not make the texture hard, such as making the mesh of the grinding paper finer or increasing the number of grinding processes when creating naps, can be considered, but even if a short nap is obtained, nubuck-like artificial leather The disadvantage is that it is not possible to obtain the precise nap that is characteristic of .

On the other hand, in order to obtain a dense nap, it is generally possible to increase the density of the fibers that make up the sheet, but it is also possible to obtain a high fiber density by adding stiffness in the thickness direction by means such as pressing. The result is a paper-like texture, which is far from the desired leather-like texture.

Another possibility is to increase the shrinkage of the sheet by heating or modifying the fibers themselves to increase the fiber density, but in general, when the fiber density is high, the sheet texture tends to be hard and dense. It was not possible to achieve both a short nap and a soft texture.

[Problems to be Solved by the Invention] In view of the above-mentioned points, an object of the present invention is to provide a method for manufacturing nubuck-like artificial leather having a high fiber density, dense and short naps without impairing the texture. There is a particular thing.

[Means for Solving the Problems] The present invention that achieves the above-mentioned objects has the following configuration.

That is, the method for producing nubuck-like artificial leather of the present invention is as follows:
After developing microfibers mainly from the conjugate fibers in the surface layer of a nonwoven fabric made of conjugate fibers that can be made into ultrafine, the surface layer has an apparent fiber density of 0.30 g/d or more and a porosity of 70% or less. This method is characterized by applying an elastic polymer to the nonwoven fabric, coagulating the elastic polymer in a dry or wet process, and then ultrafine the composite fibers that mainly constitute the inner layer of the nonwoven fabric.

In the method for producing nubuck-like artificial leather of the present invention, preferably, the ultrafine fibers are ultrafine fibers of 0.1 denier or less, or preferably, the coagulation of the polymeric elastic material is In the case of a dry coagulation method, the amount of the elastic polymer applied is 15% by weight or less, or preferably, when the coagulation of the elastic polymer is a wet coagulation method, the amount of the elastic polymer applied is 15% by weight or less. The amount is 100% by weight or less.

[Action Co. The present invention will be explained in more detail below.

In the present invention, in a nonwoven fabric in which fibers are three-dimensionally entangled, a dense and short nap is obtained in the surface layer by grinding the fiber layer in which the fibers are entangled with high density, while in the inner layer, It is characterized by the fact that a flexible texture is obtained by interposing an elastic polymer material in a state in which the fibers constituting the nonwoven fabric are restrained without being directly bonded to each other.

In order to obtain such a structure, the method of the present invention uses a nonwoven fabric made of composite fibers that have a dense structure and can be made into ultra-fine fibers. The desired purpose was achieved by skillfully combining the process of adding body to the fabric, and first, ultrafine fibers were developed from the conjugate fibers mainly in the surface layer of the nonwoven fabric with a dense structure. After that, an elastic polymer material is applied to the nonwoven fabric, and the elastic polymer material is coagulated in a dry or wet process.Furthermore, the composite fibers that mainly constitute the inner layer of the nonwoven fabric are made extremely fine.

Here, the surface layer is a portion that is mainly composed of fibers and forms naps by grinding to become the surface of the nonwoven fabric, and its thickness is 0.3M or less in practical terms such as the number of times of grinding. It is preferable.

In other words, if the surface layer to be ground is a fiber layer in which the fibers are entangled with each other at a high density, the entanglement of the fibers will be strong and the resistance during grinding will be large, resulting in short naps and Because they are highly entangled, a dense nap can be obtained. Furthermore, if the porosity of the surface layer before applying the polymeric elastic material is small, the proportion of the polymeric elastic material will decrease, and in products, due to the difference in dyeability, fibers and polymeric elastic material will be separated. This reduces the occurrence of a quality defect called irritability, where the colors of the napkins differ from each other, and it is possible to obtain a fine nap with a good appearance.

In particular, as a means to reduce the porosity, an appropriate polymeric material that has a different solubility from the polymeric elastomer and can be eluted and removed later is used for the purpose of maintaining shape and softening the texture during processing. However, in this case, it is undesirable because the adhesion between the fibers and the polymeric elastic body is hindered, resulting in longer chips and poor density. A suitable porosity is required.

From this point of view, according to the findings of the present inventors, the state of the surface layer of a nonwoven fabric made of composite fibers before developing ultrafine fibers, the fiber density is 0.30 g/cd or more; Particularly preferably, it is necessary that the fiber layer is entangled at a high density of 0.35 g/cnf or more, and when the fiber layer is entangled at such a high density, it is possible to grind such a fiber layer to make it dense. It is possible to obtain short chips, and the porosity of the surface layer is 7.
It is important that it be 0% or less.

The method for obtaining a sheet having a structure in which the surface layer of the nonwoven fabric, preferably only the surface layer of the nonwoven fabric, is highly densely entangled with ultrafine fibers is not particularly limited, but preferably a nonwoven fabric made of composite fibers that can be made ultrafine, Shrink it by heating or other means, and then heat press it using a calendar roll or the like so that only the surface layer has an apparent fiber density of 0.30 g/cm as described above.
After increasing the density so that the porosity is 2 or more and the porosity is 70% or less, the composite fibers in that part are made ultra-fine, and a high-speed fluid flow is collided with the fibers, which uses the energy to tightly entangle the ultra-fine fibers in the surface layer. It is preferable to use a method that gives

According to the findings of the present inventors, the most preferably ultrafine composite fibers are sea-island composite fibers and/or sea-island composite fibers as described below.
Alternatively, a nonwoven fabric that is a mixed spun composite fiber is shrunk by heating or hot pressing to make the surface layer particularly dense, and then the bonding components are destroyed and removed using the energy of a high-speed fluid flow to produce the composite fiber. It is preferable to use a method in which the particles are made extremely fine and at the same time, dense entanglement is achieved by the high-speed fluid flow.

In this case, a solvent that dissolves the bonded components is applied by a method such as coating to further densify the material, and the collision energy of the high-speed fluid flow does not reach the inner layer, but is more effectively consumed only in the surface layer. It is also possible to entangle ultrafine fibers.

Here, high-speed fluid flow refers to liquid or gas that is pressurized and injected from a nozzle or slit with a small hole diameter to create a high-speed fluid flow that collides with a fibrous sheet and uses the energy to entangle the fibers. The fluid is preferably a liquid from the viewpoint of the magnitude of collision energy and ease of handling, and water is most preferably used.

The pressure applied to the fluid stream, such as the liquid, may be any pressure that can destroy and remove the binding components of the ultrafine fiber-forming fibers in the surface layer, and have the effect of both forming ultrafine fibers and densely entangling them, and is not particularly limited. However, it may be selected as appropriate depending on the ease with which the ultrafine fiber-forming fibers are formed into ultrafine fibers and the developed ultrafine fibers are entangled, but it is generally 30 kg/arr to 200 kg/c.
A range of nf is preferred.

Next, regarding the inner layer of the nonwoven fabric, it is necessary that the ultrafine fibers are restrained in a state where the polymeric elastic material is interposed in the spaces between and around the fibers, without directly adhering the ultrafine fibers to each other. By exhibiting such a structure, it is possible to give the ultrafine fibers a certain degree of freedom while suppressing deformation such as dimensional changes due to physical effects, giving the sheet good texture and physical properties. It is possible to give them at the same time.

Therefore, in the inner layer of the nonwoven fabric, the polymeric elastic material is present in the spaces between the fibers and around the fibers, forming a structure that exhibits physical properties that can withstand physical action. As a method for realizing a restrained state, a polymer elastic material is applied to the inner layer nonwoven fabric portion made of composite fibers before removing the binding component of the composite fibers, and then,
A method that removes bound components can be preferably used.

That is, as described above, after developing ultrafine fibers from the composite fibers mainly in the surface layer of the nonwoven fabric by fluid flow treatment or the like, applying an elastic polymer to the nonwoven fabric and coagulating the elastic polymer, Furthermore, a method is used in which the composite fibers that mainly constitute the inner layer of the nonwoven fabric are made extremely fine.

The amount of the polymeric elastomer to be applied may be appropriately selected depending on the balance of texture, physical properties, etc., and the application method.

For example, if the coagulation method of the polymer elastomer is a dry method, the texture tends to become hard, so it is preferable that the effective proportion is 15% or less with respect to the weight of the fibers forming the nonwoven fabric. The content is preferably 10% or less. Furthermore, in the case of a wet method, the amount is preferably 100% or less, most preferably 60% or less, based on the weight of the fibers forming the nonwoven fabric.

The method of applying the elastic polymer is that the elastic polymer restrains the fibers to some extent so that the fibers can have a degree of freedom in the inner layer of the sheet, making it possible to impart a good texture. Any method may be used, and there is no particular limitation, but a method in which a solution, emulsion, or dispersion of a polymeric elastomer is applied by a method such as impregnation or coating, and then coagulated or solidified by a dry or wet method can be used as appropriate. .

In the present invention, the ultrafine fibers that ultimately form the nonwoven fabric have a supple texture, a soft touch, and a fineness of 0. It is preferably 1 denier or less, more preferably 0.05 denier or less.

When the fineness is small, there are many points where the fibers become entangled with each other when the density of the nonwoven fabric is the same, which not only makes it possible to disperse stress when subjected to physical action, but also makes it easier to obtain a dense and short nap. .

Composite fibers that can be made ultra-fine include conventionally known ultra-fine fiber-forming conjugate fibers, in other words, ultra-fine fibers can be obtained relatively easily by applying physical action or removing binding components. Various conjugate fibers such as sea-island conjugate fibers, mixed spun conjugate fibers, and peelable conjugate fibers can be used as appropriate.

Various types of ultrafine fibers can be used as long as they are made of polymeric substances that have the ability to form fibers, such as nylon 6
, polyamides such as nylon 66, polyesters such as polyethylene terephthalate and polybutylene ethylene phthalate, polyolefins such as polyethylene and polypropylene, and polymeric substances such as polyacrylic nitrile.

Furthermore, polyethylene, boristyrene, polypropylene, etc. can be used as the binding component or the dissolving and removing component of the ultrafine fiber-forming conjugate fiber.

In the method of the invention, grinding (
Fluffing and raising by buffing or the like is carried out at an appropriate time after the application of the polymeric elastomer and after or before making the inner layer conjugate fiber extremely fine.

In the present invention, the apparent fiber density of the surface layer of the nonwoven fabric is measured by a method in which a thin slice of 0.3 mm or less is sliced from the surface of the nonwoven fabric and the thickness, weight, and date are measured to calculate the density. Yes, and in the following examples, the thickness is 0
．． Calculations were made by slicing into 3 mm pieces.

The porosity is measured using the following formula from the calculated apparent fiber density and the specific gravity of the fiber.

Porosity (%) = 100 - (apparent fiber density ÷ fiber specific gravity) XIO [l
[Examples] Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to the following Examples.

Example 1 A 3-denier two-branched seabird-type composite fiber (island component: polyamide, 30% by weight, number of islands: 36: sea component: boristyrene 70% by weight) was cut to a length of about 51 mm and a number of crimps of about 14/ inch of fiber.

Using this fiber, a web was formed by passing it through a card and a cross wrapper, and a nonwoven fabric was made by a twenty-one dollar punch process.

The nonwoven fabric thus obtained has a basis weight of 288 g/d.
The density was 0.151 g/ad.

The obtained nonwoven fabric was shrunk in hot water, further pressed using a calendar roll, and dried to a basis weight of 377 g/
A sheet having a thickness of 1.1 mm and a density of 0.343 g/ad was obtained.

When a part of this sheet was thinly sliced from the surface using a slicing machine and analyzed, the basis weight of the surface layer was 110 g/rd, the thickness of the surface layer was 0.3 mm, and the density of the surface layer was 0.368 g/cu! , the porosity of the surface layer is 65%
Met.

Furthermore, for this nonwoven fabric sheet, the pore diameter is 0.25 mm.
A high-speed water jet was sprayed at a pressure of 100 kg/car from a nozzle in which small holes with a pitch of 1 mm were arranged in a row.

This sheet was impregnated with a water emulsion of polyurethane resin to give an amount of 15% based on the weight of the island component polyamide of the sheet. This sheet is immersed in trichlorethylene,
After repeated squeezing to remove a certain amount of polystyrene, #1
Grinding was repeated with 80 mesh sandpaper to a grinding depth of 0.05 mm to obtain a fiber sheet.

Furthermore, the fibrous sheet obtained by dyeing with a 1:2 type metal complex dye at normal pressure was a nubuck-like artificial leather having dense and short naps and a supple and soft texture.

Example 2 The date obtained in Example 1 was 377 g/n {thickness 1.1
n++n, density 0.343g/cnf and surface date 110g/rr? , thickness 0.3mm, density 0.
A fibrous sheet having a weight of 368 g/ad and a porosity of 65% was impregnated with 10% dimethylformamide of polyurethane to give it 60% of the weight of the island component polyamide of the nonwoven fabric, and coagulated in water at 30°C.

After drying this sheet, it was repeatedly dipped in trichlorethylene and squeezed to remove the sea component polystyrene.
Grinding is repeated with 0 mesh sandpaper until the grinding depth is 0.
．． Grinding was done by 0.5mm.

The thus obtained sheet was further dyed with a 1:2 type metal complex dye at normal pressure. The fibrous sheet thus obtained was a good nubuck-like artificial leather having dense, short chips and a soft texture.

Comparative Example 1 The date obtained in Example 1 was 288 g/rrf, the density was 0,
A nonwoven fabric of 151 g/ad is shrunk in hot water, further pressed using a calendar roll, and dried to give a date of 405 g/m, a thickness of 1.38 mm, and a density of 0. 2
A nonwoven fabric sheet weighing 93 g/ad was obtained. When a part of this sheet was thinly sliced from the surface using a slicing machine and analyzed, the basis weight of the surface layer was 86 g/rr? ，
The thickness of the surface layer is 0.29 mm, and the density of the surface layer is 0. 2
97 g/cul, and the porosity of the surface layer was 7↓%.

This sheet was impregnated with a water emulsion of polyurethane resin to give an amount of 15% based on the weight of the island component polyamide of the sheet.

This sheet was repeatedly dipped and squeezed in trichlorethylene to remove the sea component polystyrene, and then ground repeatedly with #180 mesh sandpaper until the grinding depth was 0.0.
After 5 mm of grinding, the sheet was further dyed with a 1:2 type metal complex dye at normal pressure.

Although the thus obtained fibrous sheet has a soft texture, it is rougher and has longer naps in terms of quality than those of Examples 1 and 2, and is different from the nubuck texture. Rather, it was an artificial leather that could be described as suede-like.

[Effects of the Invention] As described above, according to the manufacturing method of the present invention, nubuck-like artificial leather having a dense and short nap can be obtained without impairing the feel.

Claims (4)

[Claims] (1) Apparent fiber density in the surface layer is 0.30g/cm^2
After developing ultrafine fibers from the conjugate fibers mainly in the surface layer of a nonwoven fabric made of conjugate fibers that can be ultrafine and have a porosity of 70% or less, a polymer elastomer is added to the nonwoven fabric and the polymer A method for producing nubuck-like artificial leather, which comprises coagulating an elastic body in a dry or wet process, and then ultrafine the composite fibers that mainly constitute the inner layer of the nonwoven fabric. (2) The method for producing nubuck-like artificial leather according to claim (1), wherein the ultrafine fibers are ultrafine fibers of 0.1 denier or less. (3) The nubuck preparation according to claim (1), characterized in that the coagulation of the elastomer polymer is performed by a dry coagulation method, and the amount of the elastomer polymer applied is 15% by weight or less. Method of manufacturing leather. (4) The nubuck preparation according to claim (1), wherein the coagulation of the elastic polymer is performed by a wet coagulation method, and the amount of the elastic polymer applied is 100% by weight or less. Method of manufacturing leather.