JPH0253540B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing an artificial leather sheet obtained by using a composite fiber of an elastic fiber generation type and a composite fiber of an inelastic ultrafine fiber generation type. be. [Prior Art] Conventionally, suede-like artificial leather with raised naps is obtained by buffing the surface of a composite sheet in which a fiber sheet is coated with a polymeric elastic material, or a composite sheet is coated with a polymeric elastic film. It is well known to produce so-called silver-finished artificial leather with a silver 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 fiber bundles made of microscopic collagen that natural leather has cannot be produced by conventional methods. In other words, with conventional artificial leather having a structure consisting only of fibers, the appearance quality of artificial leather,
The physical properties and processability thereof are insufficient, and in order to improve them, a polymeric elastomer is added to the fiber sheet. Therefore, compared to natural leather, artificial leather has had the disadvantages of having a rubbery feel, poor drapability, and poor surface density. Moreover, since the polymeric elastic body is applied to the fiber sheet from outside the sheet, a related process is required, and another major drawback is that the process becomes extremely complicated. [Problems to be Solved by the Invention] The present invention provides a method for producing an artificial leather sheet that is free from the above drawbacks, is flexible, has high drapability, and has a surface quality rich in luxury. [Means for Solving the Problems] The present invention provides a composite fiber a that generates an elastic fiber A surrounded by an inelastic polymer so that the elastic fiber component is not exposed on the fiber surface, and a composite fiber a whose single yarn is 0.7 denier or less. Composite fiber B that generates inelastic ultrafine fiber B is used, and the residual fiber ratio A/B is 5/95 to 70/30 by weight.
After forming a nonwoven fabric entangled sheet, a step of heat shrinking in a gas or liquid having a temperature higher than the softening point of the inelastic polymer in conjugate fiber a, converting the conjugate fibers a and b into elastic fibers A and non-elastic fibers. Elastic microfiber B
The present invention relates to a method for producing an artificial leather sheet, which comprises performing a step of generating , and then heat-treating the elastic fiber A in a gas having a temperature higher than the melting point of the elastic fiber A to melt the elastic fiber A. The present invention is capable of shrinking a nonwoven entangled sheet that is a mixture of composite fibers that generate elastic fibers and composite fibers that generate inelastic ultrafine fibers. Through the combination of steps, the melt of elastic fibers adheres to the inelastic ultrafine fibers and/or their fiber bundles entangled with each other in the sheet, resulting in a flexible and strong artificial leather sheet. As mentioned above, natural leather, which is treated as a luxury product, has a structure consisting of fine collagen fibers and their fiber bundles, which are three-dimensional and dense. The present invention was arrived at as a result of intensive research based on the idea that it should have a tissue structure. The artificial leather sheet obtained by the present invention is a mixed fiber sheet containing elastic fibers A and inelastic ultrafine fibers B obtained from two or more types of composite fibers a/b. The mixed fiber sheet can be produced by mixing fibers in the process up to raw cotton or raw cotton, or by forming each web and/or initial entangled sheet of fibers independently and then stacking them and needle punching and/or
Alternatively, there is a method of performing high-speed fluid treatment to form a single nonwoven entangled sheet, and either method can be applied. The composite fiber used in the present invention is not particularly limited and any known method can be applied, but from the viewpoint of passability through the process of cards etc., the composite fiber must be one in which the elastic fiber component is not exposed on the surface of the fiber, or one that can be easily processed. Examples of fibers that do not cause fibrillation include sea-island type polymer array fibers, mixed spun fibers, etc. Polymer array fibers are particularly suitable composite fibers of the present invention. As the polymer forming the elastic fiber A used in the present invention, one or two types having elasticity such as polyester, polyamide, polyurethane, diene polymer and copolymer thereof, polyacrylic, polystyrene, fluororesin polymer, etc. More than one species can be used. To give a more detailed example of composite fiber a containing elastic fiber A, the elastic polymer includes polyester elastomer consisting of polybutylene terephthalate as a hard component, polytetramethylene glycol as a soft component, various polyamides as a hard component, and a soft component. As the material, polyamide elastomer made of polytetramethylene glycol or polyester polyamide polymer is used, and polystyrene and copolymers thereof are used as the polymer surrounding the elastic polymer. As the polymer forming the inelastic ultrafine fiber B,
Melting linear polymers having fiber-forming ability such as polyester, polyamide, polypropylene, and polyethylene are suitable, and one or two of these are preferred.
More than one species 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. Further, for fibers such as sea-island type fibers in which ultra-fine treatment is achieved by removing a part of the polymer constituting the composite fiber, the following polymers are used as the removed component. For example, one or more of polystyrene and its copolymers, polymethyl methacrylate, polyvinyl alcohol, polyamide, polyester and its copolymers can be used.
Composite fibers a and b are spun using such polymers. These composite fibers a and b are subjected to processes such as liquid bath, steam or dry heat stretching, crimping, cutting, and opening to produce raw cotton. These methods are not particularly limited, and all conventionally known methods for producing short fibers can be applied. The thickness of the fibers after stretching used in the present invention is 10
Denier or less is preferred, and 5 denier or less is particularly preferred. In the case of the composite fiber b containing the inelastic fiber B, the composite fiber has a denier of 0.5 to 10, and the single yarn after ultrafine treatment has a denier of 0.7 denier or less, preferably 0.3 denier or less. In order to mix composite fibers a surrounding elastic fibers A and composite fibers b containing inelastic ultrafine fibers B in the process of producing raw cotton or raw cotton, it is necessary to take it under the spinneret, doubling it, stretching it, crimping it, and cutting it. Although it is possible to carry out a mixing step either during or between steps such as fiber opening, such a mixing step is preferably carried out before the drawing step in order to enhance the mixing effect and the drawing effect. The mixing ratio of composite fibers a and b varies depending on the use and purpose of the artificial leather sheet to be manufactured, but the polymerization ratio of the residual fibers is essentially elastic fiber A/inelastic ultrafine fiber B.
=70/30~5/95 is preferable, especially 50/50~10/
90 is preferred. A web is produced using conjugate fibers a and b alone or a/b mixed raw cotton. As the method, known methods such as card, cross wrapper, random wiper, etc. can be applied. The single-layer or multi-layer web obtained by this method is needle-punched and/or subjected to high-speed fluid treatment to form an entangled nonwoven 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 . During needling, needle resistance increases depending on the nonwoven fabric entangled sheet, so a smoothing oil may be applied before or during sheet formation to reduce needle resistance. There are no particular limitations on the method for performing high-speed fluid processing, and conventionally known methods can be applied. Among them, a so-called water jet punch, in which water is used as the fluid and is ejected as a high-speed jet stream under high pressure from a narrow orifice, is common and is a suitable method for the present invention. In this case, the orifice diameter is 0.05~1.00mm,
Preferably, 0.05 to 0.50 mm is used. The pressure to push out water is 10-200Kg/ ^cm2 , preferably 30-150Kg/cm2.
^cm2 is adopted. This spraying treatment is preferably performed repeatedly from both the front and back surfaces of the web, the initially entangled sheet, or the entangled sheet while swinging the orifice. Further, the nonwoven fabric entangled sheet of the present invention is mainly composed of nonwoven fabric, but depending on the purpose and use of the artificial leather sheet, it is also possible to have a structure that uses woven or knitted fabrics in addition to composite fibers a and b. be. When mixing webs or initially entangled sheets made of each of the composite fibers a and b described above, the composite fibers a and b web or the initial entangled sheet are combined with composite fibers a/b, a/b/a or b/a. The mixed fiber sheet is laminated as in /b and subjected to needle punching and/or high speed fluid treatment. The mixing ratio at this time is preferably the same as the mixing ratio of the raw cotton or the raw cotton described above. Conventionally, when elastic fibers are used, it has been difficult to maintain the dimensions of the fibers in a stretched state unless they are subjected to special heat treatment or the like. Elastic fibers have extremely high elongation and extremely low Young's modulus, so it has been extremely difficult to manufacture webs by using ordinary carding machines. However, the elastic fibers used in the present invention are composite fibers that are internally surrounded by other polymers so that the elastic fiber components are not exposed on the fiber surface.
The passability of machines such as 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 nonwoven entangled sheet subjected to needle punching and/or high-speed fluid treatment is shrunk by liquid and gas to form a high-density nonwoven entangled sheet. The contraction temperature at this time is a temperature higher than the softening point of the polymer surrounding the elastic fibers A, and the elastic fibers A are contracted in one or more stages. Preferably, the shrinkage treatment is performed at a temperature equal to or higher than the softening point of each component constituting the conjugate fiber a and/or the conjugate fiber b. By the shrinkage treatment, it is possible to shrink the nonwoven fabric entangled sheet to an area shrinkage rate of at least 20% or more, and in some cases, 50% or more. As described above, according to the present invention, it is possible to obtain a high-density nonwoven fabric entangled sheet that cannot be obtained by conventional methods. The reason why high-density nonwoven entangled sheets can be made is that in addition to the heat shrinkage of each fiber component itself, the polymers other than the elastic fibers A, which regulate the elastic recovery of the composite fibers a surrounding the elastic fibers A, undergo heat treatment. Since the elastic fibers A are softened and this restriction is lifted, the shrinkage rate increases as the elastic fibers A recover. It is preferable that the density of the nonwoven fabric entangled sheet after shrinkage is higher, because when it is made into artificial leather, a more substantial feeling can be imparted. In the conventional method, a form fixing agent such as polyvinyl alcohol is added to the nonwoven fabric entangled sheet obtained by shrinkage treatment to make it easier to post-process the composite fiber before ultrafine treatment. However, the nonwoven fabric entangled sheet after the shrinkage treatment according to the present invention has a high density with elastic fibers and inelastic ultrafine fibers intricately and densely intertwined, so the sheet is extremely strong. It is. Therefore, the entangled nonwoven fabric entangled sheet, which has been subjected to shrinkage treatment to have a high density, can be subjected to ultrafine fiber treatment without a shape fixing agent. In the case of composite fibers in which ultrafine fibers and their fiber bundles are revealed by removing one component, ultrafine fiberization is performed by removing unnecessary components with a solvent. After the ultra-fine treatment, the sheet is heat-treated in a gas having a temperature higher than the melting point of the elastic fibers A, thereby melting the elastic fiber component A and forming the inelastic ultra-fine fibers and/or their fiber bundles entangled with each other in the sheet. It can be bonded to a strong sheet. This treatment is carried out without compressing the sheet, so it is a preferred method for obtaining a soft texture. The reason is that when the sheet is heat-treated without being compressed, the melted elastic fibers A are bonded in dots, so although the bond is strong, the fibers in the sheet can move easily, making it possible to achieve both softness and strength. . If the other sheet is heat-treated while being compressed, the melted elastic fibers A form a linearly bonded structure, which tends to harden the texture and inevitably result in a paper-like texture. As described above, the present invention introduces an adhesive component that acts as a binder into a sheet in advance in the form of fibers, and then melts and adheres the entangled inelastic ultrafine fibers and/or their fiber bundles. Since the ingredients are non-porous and fine in size, they can be made into flexible and strong sheets. It goes without saying that the degree of such treatment requires at least a temperature and time for the elastic fibers A to melt and adhere to each other to exhibit a binder effect, but it also provides an artificial leather sheet with strength and abrasion resistance that can be put to practical use. For this purpose, it is preferable that most of the elastic fiber component be melted to the extent that it loses its fibrous form. Since the nonwoven fabric entangled sheet processed in this way can have a strong structure, it can be processed by conventionally known methods such as buffing and/or dyeing without applying a binder from the outside of the sheet to create a suede-like artificial sheet with raised naps. It can be provided as leather or silver-finished artificial leather with a silver surface. In addition, by selecting elastic fibers with extremely low strength compared to inelastic fibers, it is possible to have the melted elastic fiber components present only in the inner layer, with no or almost no melted elastic fiber components being contained in the raised part after buffing. be. In this case, the piloerection surface is smooth and there are no piloerection spots or staining spots after dyeing. The manufacturing method of the present invention includes a step of heat shrinking in a gas or liquid, and a step of melting the elastic fiber A by heat treatment in a gas having a melting point higher than the melting point of the elastic fiber A. A large shrinkage occurs based on the fibers A, and in the latter step, the elastic fibers are melted, so that the inelastic fibers B are crimped and bonded together by the elastic (shrinkable) component in non-fiber form. This means that in the artificial leather sheet of the present invention, the shrinkage components do not remain as fibers and hinder the elongation of the sheet, and a large amount of shrinkage can be reversibly (elastically) recovered. That is, the remarkable elasticity and stretchability of the artificial leather sheet according to the present invention is based on the technical concept of adhesively fixing the inelastic fibers in a state in which the inelastic fibers are forcibly crimped by the remarkable contraction of the elastic fibers. 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. [Effects of the Invention] According to the present invention, the following effects can be obtained. (1) Since a composite fiber is used in which the elastic fiber component is not exposed on the fiber surface, processability of cards, etc. is good. (2) Since an artificial leather sheet can be obtained without adding a shape fixing agent or a polymeric elastomer, the manufacturing process can be simplified. (3) Compared to the conventional method of applying a binder from the outside of the sheet, the melted elastic fibers act more effectively in intertwining and fixing, so an artificial leather sheet that is flexible and has excellent drapability can be obtained. (4) Since it is a high-density sheet and the elastic fibers melt and act as a binder, it has good abrasion resistance and strength. [Example] Next, an example according to the present invention will be shown. The measurement of the product in the present invention is carried out by the following method. (1) Tensile strength: JIS-L1079 5.12.1 (2) Bending resistance: JIS-L1079 5.17 A method (3) Drape coefficient: JIS-L1079 5.17 F method (4) Brush Wear: According to ASTM: D1175. Using Seafa abrasion tester Load: 3628.2g Brush: Nylon Brush length: 13mm Unless otherwise specified, all "percentages" and "%" are based on weight. Example 1 Polyester elastomer (“Hytrel” HTC2551 manufactured by Toyo Products Co., Ltd., melting point 169°C) as the island component,
A component ratio of 50/50 consisting of a polystyrene-based copolymer as a sea component, a component ratio of 50/50 consisting of a sea-island type polymer array fiber x with a number of islands of 16 and a thickness of 9.0 denier, polyethylene terephthalate as an island component, and polystyrene as a sea component. 50, the number of islands is 36, and the thickness is 9.0 denier using sea-island type polymer array fiber y, x/y is
An unstretched tow was produced by combining the mixture so that the ratio was 20/80. This unstretched tow was stretched 3.0 times in a liquid bath at 80°C, and then crimped at 13 to 18 threads/inch through a crimper. After that, apply a silicone oil, dry it, cut it to a length of 51 mm, and cut it into x/y.
A mixed raw cotton consisting of was obtained. This raw cotton was carded and cross-strapped to form a web with a basis weight of 605 g/m ² . The card passing property at this time was extremely good. This web was needle punched with a needle density of 3000 needles/cm ² to obtain a fiber sheet with a basis weight of 618 g/m ² and an apparent density of 0.242 g/cm ² . Thereafter, the fiber sheet was immersed in warm water at 65° C. for 3 minutes to shrink. The area shrinkage rate at this time was 62.2%. This fiber sheet was washed with trichlorethylene to remove sea components and dried. At this time, the sheet weight is 866g/m ² and the apparent density is
This sheet, which had a weight of 0.579 g/cm ² , was heat treated in gas at 180° C. for 5 minutes and then sliced in the plane direction to obtain two sheets. Next, the sheet was subjected to a buffing machine to form naps on both the sliced and non-sliced surfaces. Thereafter, the raised sheet was jet dyed using a disperse dye at 120° C. for 60 minutes to obtain suede-like artificial leather having a basis weight of 290 g/m ² and an apparent density of 0.372 g/cm ² . The suede-like artificial leather thus obtained was extremely flexible and had excellent drapability, and no elastic fiber components were observed in the raised portions, and it had an elegant surface quality that was extremely close to that of suede, a natural leather. Moreover, physical properties such as abrasion resistance and strength were good as shown in Table 1. Cross-sectional photographs of the artificial leather thus obtained are shown in FIGS. 1 to 4. 1 and 2 show the surface layer portions of both surfaces, and FIGS. 3 and 4 show the inner layer portions. Table 1 shows the physical properties of the artificial leather sheets obtained in Examples and Comparative Examples. Example 2 The suede-like artificial leather obtained in Example 1 was used as a base material, and on the other hand, an unreacted polyurethane mixture containing a pigment was coated on a release paper having a grain pattern to form a dry coating film of about 5μ. Then, 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 being an adhesive 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 hot 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 removed to produce silver-covered artificial leather. The resulting silver-covered artificial leather is much more flexible than those made using conventional methods, and has excellent drapability.
It closely resembled natural leather with fine grains and creases on the surface. Comparative Example 1 Using the sea component-removed sheet obtained in Example 1, two sheets were obtained by slicing it in the plane direction without heat treatment. This sheet was subjected to napping and dyeing under the same conditions as in Example 1 to obtain suede-like artificial leather. Although the resulting product had good flexibility, it was found that some parts were torn or extremely thin due to the dyeing process, making it extremely unsuitable for practical use. Comparative Example 2 1 where the cross-sectional shape of the fiber has six radial parts
A split type fiber was used, which consisted of a book fiber E and six fan-shaped fibers F that completed the radial part, and in which E and F were exposed on the fiber surface. In this splittable fiber, E is polyethylene terephthalate, F is polyester elastomer, (“Hytrel” HTC-2551)
It was made by melt spinning with E/F=50/50 and a thickness of 3d. This spun undrawn yarn is combined into a tow,
The film was stretched three times in a liquid bath where the first bath was 60°C and the second bath was 80°C. Next, the fibers were crimped and cut to a fiber length of 51 mm to produce raw cotton. When this raw cotton was passed through a roller card and a cross wrapper to make a web, there seemed to be no problem at the start, but after 15 to 20 minutes, carding was stopped because a large number of neps occurred. When the original problem was investigated, it was found that the split-type fabric was fibrillated and the fibers F were clogging the garnet wires of the card. When the amount of raw cotton fed to the card was significantly reduced, the time required for neps to occur was lengthened, but the problem was still not resolved. This web was laminated into four sheets and needle punched at 3000 pieces/cm ² to give a fabric weight of 670 g/m ² and a thickness of 3.19.
A nonwoven fabric sheet of mm was produced. Subsequently, this nonwoven fabric was passed through hot water at 85° C. for 3 minutes to shrink it. The area shrinkage rate at this time was 32%. It was observed that most of the splittable fibers in the sheet were fibrillated by this treatment. Next, the sheet was continuously subjected to thermal compression treatment at 160° C. between heated rollers at a pressure of 3 kg/cm ² . This treatment gave the sheet a paper-like texture and made it extremely hard. At this time, F maintained its fibrous shape, but it was observed that it was sufficiently adhered to E. Thereafter, the same slicing, buffing, and dyeing as in Example 1 were performed to obtain suede-like artificial leather. The product obtained had a hard texture, extremely poor quality of raised hair, and some parts were torn due to dyeing and some parts were extremely thin. Therefore, this sheet had poor physical properties and was extremely unsuitable for practical use as artificial leather. Comparative Example 3 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 unstretched 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 slutper 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 .
A fiber sheet having a basis weight of 640 g/m ² and an apparent density of 0.182 g/cm ² 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%. The fiber sheet was then impregnated with a 10% aqueous solution of polyvinyl alcohol and dried, giving the fiber sheet a solid content of 22% polyvinyl alcohol. The sheet was washed with trichlene to remove sea components and dried. Next, a 12% dimethylformamide solution of polyurethane was impregnated, and then coagulated in a wet method, polyvinyl alcohol was removed with hot water at 80° C., and then dried. At this time, the amount of polyurethane applied was 37% based on the polyethylene phthalate fiber. Thereafter, the obtained sheet was sliced into two sheets, and subjected to a bubbling 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℃ for 60 minutes to determine the basis weight.
A suede-like artificial leather having a weight of 210 g/m ² and an apparent density of 0.247 g/cm ² was obtained. This suede-like artificial leather had strong repellency and a rubber-like feel, and was clearly inferior to Example 1 in drapability, suppleness, and surface quality. 【table】

[Brief explanation of the drawing]

Figures 1 and 2 are 140x cross-sectional photographs of the vicinity of the surface layer of the suede-like artificial leather obtained by the present invention. Figures 3 and 4 are 140x cross-sectional photographs of the inner layer of the suede-like artificial leather obtained by the present invention.

Claims (1)

[Claims] 1 Composite fiber a that generates elastic fiber A surrounded by an inelastic polymer so that the elastic fiber component is not exposed on the fiber surface, and composite fiber b that generates inelastic ultrafine fiber B whose single yarn is 0.7 denier or less. use,
After forming a nonwoven fabric entangled sheet so that the residual fiber ratio A/B is 5/95 to 70/30 by weight, it is heat-shrinked in a gas or liquid at a temperature higher than the softening point of the inelastic polymer in composite fiber a. a step of generating elastic fibers A and inelastic ultrafine fibers B from composite fibers a and composite fibers b, and then heat-treating in a gas at a temperature higher than the melting point of elastic fibers A to melt the elastic fibers A. A method for producing an artificial leather sheet characterized by: