JPH0316427B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for manufacturing an artificial leather sheet obtained by using a conjugate fiber of the type that generates elastic fibers and a conjugate fiber of the type that generates ultrafine inelastic fibers.

(Prior art) Conventionally, suede-like artificial leather with raised naps is obtained by buffing the surface of a composite sheet in which a polymeric elastic material is added to a fiber sheet, or silver is produced by adding a polymeric elastic material film to a composite sheet. It is well known to produce so-called silver-finished artificial leather with a surface formed thereon. Although many methods for producing artificial leather have been proposed based on such methods in an attempt to approximate the structure and properties of natural leather, which is treated as a luxury item, no satisfactory artificial leather has yet been obtained.

The reason why conventional methods are unsatisfactory is that the three-dimensional, dense structure of fibers and/or fiber bundles made of fine collagen fibers of natural leather cannot be produced by conventional methods. In other words, it is desirable that artificial leather be composed only of fine fibrous substances like natural leather, but in the case of artificial leather sheets made only of fibers manufactured by conventional techniques,
This is because the mechanical properties such as strength and elongation properties, tear strength, and resistance to rolling are significantly inferior, and furthermore, the processability is insufficient, making it extremely impractical. In order to compensate for these drawbacks, it is often done to add an elastic polymer to the fiber sheet, but this method is not satisfactory because a coarse elastic polymer film is interposed between the fibers and/or fiber bundles. If you want to obtain artificial leather that has mechanical performance and processability, it will have a rubbery feel compared to natural leather, and will have inferior sensory performance such as drapability, surface density, and touch. That is inevitable. Until now, as a means to satisfy both of these performances,
Many attempts have been made, and in addition to the above-mentioned method of applying a polymer elastic body from the outside to a fiber sheet, a method using adhesive fibers has been proposed. That is, in a sheet made of non-conjugate fibers, it is known to mix elastic fibers with inelastic fibers or to use two or more types of fibers with different melting points. Furthermore, it is known that two or more types of fiber-generating fibers having different melting points are used in sheets made of composite fibers. However, these methods have not yet been effective as methods for producing artificial leather sheets. Therefore, it has been extremely difficult to produce artificial leather that has both good mechanical performance and sensory performance using conventional techniques.

[Purpose of the invention]

The present invention provides a method for producing an artificial leather sheet that does not have the above-mentioned drawbacks, has good mechanical performance and sensory performance, and is rich in luxury.

(Structure of the Invention) The present invention is a method of increasing density by wet and/or dry heat shrinkage treatment of a fiber sheet that is a mixture of two or more types of elastic fiber-generating composite fibers and ultrafine inelastic fiber-generating composite fibers having different melting points. The composite fibers are made into a fiber sheet, the composite fibers are subjected to a thinning treatment or ultra-fine treatment, and a part of the two or more types of elastic fibers is melted by heat treatment to give a fine binder effect, and other elastic fibers are added. It is based on a combination of the steps of leaving it in the form of fibers to impart good elasticity to the artificial leather-like sheet, and the present invention cannot be achieved without this combination. By combining these steps, the inelastic fibers and/or elastic fibers are entangled in a complex and dense manner, and the molten elastic fibers form fine bonding points, which improves the structure and properties of natural leather far more than conventional methods. It can be approximated. However, it is possible to provide a method for manufacturing an artificial leather sheet that has both good mechanical performance and sensory performance.

The artificial leather sheet according to the present invention has two different melting points.
It is obtained from a mixed fiber sheet containing composite fibers that generate more than one type of elastic fibers and composite fibers that generate ultrafine inelastic fibers. The mixed fiber sheet can be produced by mixing fibers in the process up to raw cotton or raw cotton, or by forming a web and/or an initial entangled sheet of each composite fiber independently, and then stacking them and applying needle punching and/or high-speed fluid treatment. However, there is a method of forming one fiber sheet, but either method is applicable.

The form of the composite fiber used in the present invention is not particularly limited, and those obtained by known methods can be applied. For example, sea-island type polymer array fibers, mixed spun fibers, various split type fibers, etc.
In particular, polymeric array fibers are preferred for the present invention.

The polymer forming the elastic fiber used in the present invention may be one or more types having elasticity such as polyester, polyamide, polyurethane, diene yarn polymer and its copolymer, polyacrylic, fluororesin polymer, etc. , and two or more types having different melting points are used.

Methods for obtaining composite fibers containing two or more types of elastic fibers with different melting points include a method of using a composite fiber containing two or more types of elastic fibers with different melting points in one composite fiber, or a method of using a composite fiber containing two or more types of elastic fibers with different melting points, or a method of using a composite fiber containing two or more types of elastic fibers with different melting points. There is a method of selecting and using two or more types of conjugate fibers containing elastic fibers having different melting points from a group of conjugate fibers containing only elastic fibers, but any method may be used.

As the polymer for forming the inelastic fibers, meltable linear polymers having fiber-forming ability such as polyester, polyamide, polypropylene, and polyethylene are suitable, and one or more of these can be used. In particular, polyethylene terephthalate, nylon 6, and nylon 66 are preferred from the viewpoint of the physical properties and practical performance of the resulting product. In addition, for fibers such as sea-island type fibers where finer treatment and/or ultra-fine treatment can be achieved by removing some of the polymers constituting the composite fibers, the following polymers are used as the removed component. It will be done. For example, one or more of polystyrene or a copolymer thereof, polymethyl methacrylate, polyvinyl alcohol, polyamide, polyester or a copolymer thereof may be used.

Spinning such a polymer into a composite fiber,
Thereafter, the composite fibers are subjected to processes such as doubling, liquid bath, steam or dry heat stretching, crimping, cutting, and opening to produce raw cotton. These methods are not particularly limited, and known methods for producing short fibers can be applied.

The thickness of the stretched fiber used in the present invention is preferably 10 deniers or less, particularly preferably 5 deniers or less in the case of composite fibers containing elastic fibers. In the case of composite fibers containing inelastic fibers, the composite fibers have a denier of 0.5 to 10, and the single fibers after ultrafine treatment have a denier of 0.7 denier or less, preferably 0.3 denier or less.

When mixing conjugate fibers a containing an elastic polymer and conjugate fibers b containing inelastic fibers, in the process up to raw cotton or raw cotton, it is necessary to take up under the spinneret, doubling, stretching, crimping, and cutting. The mixing step can be carried out either during or between steps such as fiber opening, but it is preferable to carry out such a mixing step before the drawing step in order to enhance the mixing effect and the drawing effect. The mixing ratio of a and b varies depending on the use and purpose of the artificial leather to be manufactured, but it is preferable that the weight ratio of the residual fibers is elastic fiber/inelastic fiber = 70/30 to 5/95, particularly 50/50 to 5/95. 10/90 is preferred. Furthermore, the two or more types of elastic fibers having different melting points are divided into elastic fibers ax that melt in a subsequent heat treatment step and elastic fibers ay that do not melt. That is, they are divided into elastic fibers ax, which have a melting point below the heat treatment temperature, and elastic fibers ay, which have a melting point higher than the heat treatment temperature.
It is preferable to mix so that ay=10/90 to 90/10.

A web is made using the a, b or a/b raw cotton thus obtained. The method is card,
Methods such as cross wrapper and random wet bar can be applied. The single-layer or multi-layer web obtained by such a method is needle-punched and/or subjected to high-velocity fluid flow treatment to form a fibrous sheet. When performing needle punching, the needle density may be selected depending on the purpose and use, but is preferably 200 to 7000 needles/cm ² . Such a needle punch reduces needle resistance. Alternatively, for the purpose of increasing the density of the sheet, a smoothing oil may be applied before and/or during sheet formation. When performing high-speed fluid treatment, the method is not particularly limited and any known method can be applied, but among these, the so-called water jet punch, which uses water jetted under high pressure from a thin orifice as a high-speed jet stream, is common. This is a method suitable for the present invention. In this case, the orifice diameter is 0.05-1.00mm, preferably 0.05-0.5mm
is used. The pressure to push out water is generally 10
-500Kg/ ^cm2 , preferably 30-300Kg/ ^cm2 . This jetting treatment is preferably performed repeatedly from both the front and back sides of the sheet while rocking the orifice. Furthermore, although the fiber sheet of the present invention is mainly composed of nonwoven fabric, it is also possible to have a structure that uses woven or knitted fabrics in addition to a and b, depending on the purpose and use of the artificial leather.

When mixing webs or initially entangled sheets consisting of each of a and b described above, the a and b webs or initial entangled sheets are mixed together as a/b, a/b/a or b/a/b.
The mixed fiber sheets are laminated and needle punched and/or high-speed fluid treated to form a mixed fiber sheet. The mixing ratio at this time is preferably the same as the mixing ratio of the raw cotton or the raw cotton described above. Of course, a includes ax and ay here.

Conventionally, when using elastic fibers, it has been difficult to maintain the dimensions of the fibers in a stretched state unless they are subjected to treatments such as heat treatment. Furthermore, since elastic fibers have extremely high elongation and extremely low Young's modulus, it has been extremely difficult to manufacture webs by applying them to ordinary carding machines. However, since the elastic fiber used in the present invention is a composite fiber that is used in combination with other polymers, the passability of the fiber through machines such as drawing and carding can be greatly improved. In order to improve this machine passability, it is preferable to make the thickness of the elastic fibers in the composite fiber containing elastic fibers thinner and to make the ratio of the elastic fibers smaller.

The fiber sheet subjected to the needle punching and/or high-speed fluid treatment is wet-shrinked and/or dry-shrinked to form a high-density fiber sheet. At this time, the shrinkage temperature is higher than the softening point of the other polymer other than the elastic polymer forming the composite fiber containing elastic fibers, and the shrinkage is performed in one or more stages. Preferably, the shrinkage treatment is performed at a temperature higher than the softening point of each component constituting a and/or b. Through the shrinkage treatment, the fiber sheet can be shrunk by 50% or more in area shrinkage, and the fiber density can also be set to 0.70 g/cm ² or more. As described above, according to the present invention, it is possible to obtain a high-density fiber sheet that cannot be obtained by conventional methods. The reason why high-density fiber sheets can be made is that in addition to the thermal contraction of each fiber component itself, polymers other than the elastic polymer that regulates the elastic recovery of composite fibers containing elastic fibers are softened by heat treatment. Since this restriction is lifted, the shrinkage rate increases due to the recovery of the elastic fibers.
Generally, the higher the density of the fiber sheet after shrinkage, the better it will be because it will give a fuller feel when made into artificial leather. Examples of composite fibers containing elastic fibers that are preferable for achieving high density include elastic polymers. As a hard component, polybutylene terephthalate,
The soft component is a polyester fabric made of polytetramethylene glycol, the hard component is various polyamides, and the soft component is a polyamide elastic body or a polyester polyamide fabric made of polytetramethylene glycol. Polymers other than elastic polymers Examples include polystyrene and copolymers thereof.

In the case of the conventional method using composite fibers that do not contain elastic fibers, the fiber sheet obtained by shrinkage treatment is not only thinned and/or ultra-fine, but also has good post-processing properties. In order to achieve this, a general method is to apply a shape fixing agent such as polyvinyl alcohol, and to add a binder such as polyurethane to improve the physical properties of the artificial leather, thereby forming an artificial leather sheet. However, the fiber sheet after shrinkage treatment according to the present invention is extremely strong because the elastic fibers and the ultrafine inelastic fibers are intricately and densely intertwined, resulting in a high fiber density. Therefore, it is possible to produce an artificial leather sheet with excellent physical properties, quality, and processability even if steps such as adding a shape fixing agent and adding a polymeric elastomer are omitted. That is, the entangled fiber sheet which has been subjected to shrinkage treatment to have a high density can be subjected to thinning and/or ultrafine fiberization treatment without a shape fixing agent. In the case of splittable conjugate fibers, ultra-fine treatment is achieved by physical and chemical treatment. In the case of conjugate fibers in which ultrafine fiber bundles become apparent by removing one component, a method such as removing unnecessary components with a solvent may be used.

After that, or simultaneously with the thinning/ultra-fine treatment,
The sheet is heat-treated to melt some of the elastic fibers in the group of two or more elastic fibers having different melting points that have been thinned and/or ultra-thinned. The heat treatment temperature is higher than the melting point of the elastic fiber with the lowest melting point among the elastic fiber groups used, and is below the melting point of the elastic fiber with the highest melting point, and the elastic fiber ax with the melting point lower than the heat treatment temperature is melted. Seshime,
Moreover, the elastic fiber has a melting point higher than the heat treatment temperature.
ay remains in fibrous form. Through such processing,
Some of the elastic fibers are melted to provide a fine binder effect, while other elastic fibers remain in the form of fibers to provide the artificial leather sheet with good elasticity. In the conventional binder application process, the general method is to externally impregnate or coat a fiber sheet with a polymeric elastomer in the form of a solution, emulsion, or dispersion. Since the polymeric elastomer film is interposed between the fibers and/or fiber bundles as a coarse mass, this becomes a factor that greatly impairs the sensory performance of the sheet, such as its flexibility and drapeability. In the present invention, a polymeric elastic body that imparts a binder effect is mixed in advance into a sheet in the form of fine and/or ultrafine fibers obtained from composite fibers, and heat treatment is performed to melt the elastic fibers to impart a binder effect. In order to achieve this, the size of the binder in the sheet is reduced to an extremely small size by conventional methods, and it forms fine bonding points with the inelastic ultrafine fibers and/or the remaining unmelted elastic fibers. This gives the sheet both good mechanical and sensory performance. In particular, the elastic fibers remaining without being melted can impart good stretchability to the sheet and reduce residual strain.

The fiber sheet processed in this way can have an extremely high density and strong structure even at this stage, so it is processed by conventionally known methods such as buffing and/or dyeing without adding a binder such as polyurethane. It can be provided as a suede-like artificial leather with a silver surface or a silver-finished artificial leather with a silver surface.

Note that by selecting elastic fibers with extremely low tenacity compared to inelastic fibers, it is possible to have the elastic fibers present only in the inner layer portion, with no or almost no elastic fibers included in the raised portion after buffing. In this case, the piloerection surface is smooth and there are no piloerection spots or staining spots after dyeing.

One of the features of the present invention is the simplified process described above, but of course, during this series of processing, if necessary, heat pressing, application of a shape fixing agent such as polyvinyl alcohol, application of a binder such as polyurethane, slicing processing, etc. , additional steps such as lamination of an elastic polymer film may be performed.

Thus, the present invention has made it possible to create an artificial leather sheet that has a dense structure that closely resembles natural leather and has both good mechanical and sensory performance, something that could not be obtained using conventional techniques. .

(Effects of the present invention) According to the present invention, the following effects can be obtained.

(1) Artificial leather that is flexible and has a substantial feel can be obtained.

(2) An artificial leather sheet with excellent drapability can be obtained.

(3) Detailed and high-quality surface quality can be obtained.

(4) The manufacturing process can be simplified.

(5) Artificial leather having stretchability, wrinkle resistance, elasticity and low residual strain can be obtained.

Next, examples according to the present invention will be shown.

The measurement of the product in the present invention is carried out by the following method.

Tensile strength: JIS-L1079 5, 12, 1 Tear strength: JIS-L1079 5, 14 C method Bending strength: JIS-L1079 5, 17 A method "Ratio" and "%" unless otherwise specified ” are all based on weight.

Example 1 Polyester facultative body (“Hytrel” HTC2551 manufactured by Toyo Products Co., Ltd., melting point 169°C) as the island component,
The sea component is a sea-island type polymer array fiber A consisting of a polystyrene copolymer with a component ratio of 50/50, the number of islands is 16, and the thickness is 9.0 denier.The island component is a polyester elastomer ("Hytrel" manufactured by Toyo Products Co., Ltd.)
HTC4766, melting point 213℃), component ratio 50/50 consisting of polystyrene copolymer as sea component, number of islands 16,
A sea-island type polymer array fiber B having a thickness of 9.0 denier, a component ratio of 50/50, consisting of polyethylene terephthalate as the island component and a polystyrene copolymer as the sea component, the number of islands is 36, and a thickness of 9.0 denier. Using somatic C, A/B/C=15/10/
An unstretched tow was created by doubling the yarns to a length of 75.
After stretching this semi-stretched tow by 3.0 times in a liquid bath at 80°C,
13 to 18 threads/inch were crimped through the crimper. Thereafter, a silicone-based oil was applied thereto, dried, and cut to a length of 51 mm to obtain a mixed raw cotton consisting of A, B, and C. The raw cotton is carded and cross-wrapped to form a web with a basis weight of 550 g/ ^m2 , and this web is needle punched with a needle density of 3500 needles/ ^cm2 , resulting in a basis weight of 561 g/ ^m2 and an apparent density of 0.240.
It was made into a fiber sheet of g/cm ² . Thereafter, the fiber sheet was immersed in warm water at 80° C. for 3 minutes to shrink. The area shrinkage rate at this time was 61.7%. This fiber sheet was washed in trichlorethylene to remove sea components. The weight of the sheet at this time is 732
g/m ² , and the apparent density was 0.542 g/cm ² . This sheet was heat-treated at 180° C. for 5 minutes using a hot air dryer, and then sliced in both directions to obtain two sheets. Next, the sheet was subjected to a buffing machine to form naps on both the sliced and non-sliced surfaces. After that, the raised sheet was jet dyed using a disperse dye at 120℃ for 60 minutes to obtain a fabric weight of 263g/
m ² and an apparent density of 0.366 g/cm ² . The suede-like artificial leather thus obtained was extremely flexible and had good elasticity. The tensile strength of this suede-like artificial leather is 7.3Kg/cm vertically, 5.6Kg/cm horizontally,
The tensile elongation is 127% in the vertical direction and 172% in the horizontal direction, and the tearing strength is 3.5 kg in the vertical direction and 2.7 kg in the horizontal direction, which has good mechanical performance.The bending strength is 31 mm in the vertical direction and 24 mm in the horizontal direction, so it has excellent flexibility. It was hot.

Example 2 One component of the island components is polyester elastic body X
(“Hytrel” HTC2551 manufactured by Toyo Products Co., Ltd.,
melting point 169℃) and one other component is polyester elastic body Y (“Hytrel” manufactured by Toyo Products Co., Ltd.)
HTC4766, melting point 213℃), and the sea component consists of polystyrene copolymer Z. The component ratio X/Y/Z=
25/25/50, island number 16, thickness 9.0 denier sea-island type polymer array fiber D and Example 1 C were used to produce D/
The yarns were doubled so that C=20/80 to create an end-stretched tow. The same treatment as in Example 1 was then carried out, and as in Example 1, suede-like artificial leather with low resilience and good elasticity could be obtained.

Example 3 Using the suede-like artificial leather obtained in Example 1 as a base material, a release paper with a grain pattern was coated with a non-reactive polyurethane mixture containing a pigment to create a dry coating film of about 5 μm. Furthermore, a reactive polyurethane mixture containing a crosslinking agent and pigment is coated on top of this, and a dry coating film of approximately 20μ is laminated, the former being a silver surface layer and the latter an adhesive layer for adhering to the base material. A laminated coating film was formed. The laminated coating film and the base material were bonded together by passing them through a heated roll at 70°C, and then aged for one day to cause the polyurethane of the adhesive layer to undergo a crosslinking reaction. Next, the release paper was peeled off to produce silver-covered artificial leather. The resulting silver-covered artificial leather was extremely soft and drapable compared to those produced by conventional methods, and closely resembled natural leather with fine grains and creases on the surface.

Comparative Example 1 Component ratio 50/50 consisting of polyethylene terephthalate as the island component and polystyrene as the sea component,
A sea-island type polymer array fiber with a thickness of 9.0 denier and 36 islands was used, and a sea-island type polymer array fiber with the same components as above and 16 islands was used, and the former/latter ratio was 80/20. This semi-stretched tow was stretched 3.0 times in a liquid bath at 80°C and passed through a crimper to give it 13 to 20 crimps/inch. Thereafter, a silicone-based oil was applied, the material was dried, and the material was cut to a length of 51 mm to produce raw cotton. This raw cotton was passed through a card and a cross wrapper to create a web with a basis weight of 620 g/m ² .
Next, the web was needle punched with a needle density of 3000 needles/cm ² to give a fabric weight of 640 g/m ² and an apparent density of 0.182 g/cm 2 .
A fiber sheet of cm was obtained.

This fiber sheet was shrunk and dried by passing it through hot water at 95°C. The area shrinkage rate at this time was 32%. Next, the fiber sheet was impregnated with a 10% aqueous solution of polyvinyl alcohol and dried to impart 22% polyvinyl alcohol in terms of solid content to the fiber sheet.The sheet was washed with trichlene to remove the sea component and dried, and then impregnated with polyurethane. The material was impregnated with a 12% dimethylformamide solution, then wet-coagulated, polyvinyl alcohol was removed with 80°C hot water, and dried. The amount of polyurethane applied at this time was 37% based on the polyethylene terephthalate fiber. Thereafter, the obtained sheet was sliced into two sheets, and subjected to a buffing machine to form naps on both the non-sliced surface and the sliced surface. Next, the raised sheet was jet dyed using a disperse dye at 120°C for 60 minutes to obtain a fabric weight of 210.
g/m ² , and an apparent density of 0.247 g/cm ² was obtained. This suede-like artificial leather has strong resilience and a rubber-like texture.
The drapability, suppleness, and surface quality were clearly inferior to those of the above.

Claims (1)

[Claims] 1. A method for producing an artificial leather sheet, comprising: at least two types of elastic fiber-generating conjugate fibers (collectively referred to as a) having different melting points;
A non-woven entangled sheet is made using non-elastic ultra-fine fiber-generating composite fibers b whose single fibers are 0.7 denier or less, and the actual remaining ratio of elastic fibers to non-elastic fibers is 5/95 to 70/30 by weight. a step of thinning and/or ultrafine the conjugate fibers a and b; 1. A method for producing an artificial leather sheet, characterized by performing a combination of the following: a step of heat-treating an elastic fiber having the highest melting point below the melting point.