JPH0140151B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for producing artificial leather that is much thinner than conventional products. (Prior art) Conventionally, a composite sheet made of a nonwoven fabric sheet made of ultrafine fibers and a polymeric elastic material added as a binder has been used to create suede-like artificial leather with raised naps or a polymeric elastic material on the surface by buffing the surface. It is well known that it can be processed into so-called silver-finished artificial leather, which has been given a texture to form a silver surface. However, artificial leather using composite sheets based on non-woven fabrics is limited to relatively thick materials with a hard texture, such as materials for outer clothing such as coats, suits, and blazers, or industrial materials; The current situation is that there is nothing at all. The reason for this is that, unlike fiber sheets made of woven or knitted fabrics, composite sheets based on non-woven fabrics do not have a strong structure, so their morphology is mainly caused by the irregular entanglement of the fibers themselves or by the addition of fibers to the non-woven fabric sheet. When the composite sheet is made thinner and softer using conventional techniques, the fibers become less entangled and have a loose structure, so the resulting artificial leather has good strength and elongation properties.
This is because mechanical properties such as tear strength and resistance to rubbing are significantly reduced, making it impractical. This has been considered a fatal flaw of nonwoven fabrics. However, although this has been desired for a long time, it is extremely difficult to create ultra-thin artificial leather based on nonwoven fabrics for use in dresses, blouses, shirts, etc., which require thinness, softness, and drapability. It has been said that (Objective of the present invention) An object of the present invention is to provide a method for producing artificial leather based on a nonwoven fabric, which has excellent mechanical performance, is thin, and has good flexibility and drapability. (Structure of the present invention) The present inventors have made extensive studies to achieve the above-mentioned object, and have discovered the present invention. That is, the method for producing ultra-thin artificial leather of the present invention involves needle-punching a web made of composite fibers that mainly generate ultra-fine fibers of 0.05 denier or less to form a nonwoven fabric sheet with an apparent density of 0.18 g/cm ³ or more. This is a method for producing ultra-thin artificial leather, which is characterized by subjecting such a nonwoven fabric sheet to high-speed fluid treatment, and then subjecting it to a combination treatment of the steps of ultra-fine conjugate fibers, application of a binder, and buffing. The present invention will be explained in more detail below. The present invention uses fibers that are even thinner than conventional ultrafine fibers, needle-punches a web made of the fibers to create a nonwoven sheet in which fiber bundles are intertwined, and processes the nonwoven sheet with high-speed fluid to create single fibers. A part of the fibers is entangled to form a nonwoven structure with a mixture of fiber bundle entanglement and single fiber entanglement, and then a combination treatment of fiber ultrafine treatment, binder application, and buffing is performed to reduce the thickness. This invention relates to a manufacturing method for producing ultra-thin artificial leather, which is preferably 0.5 mm or less and has a density of preferably 0.35 g/cm ³ or more, and the present invention cannot be achieved without the above combination. There isn't. The ultrafine fiber generation type fiber used in the present invention includes:
There are no particular limitations, and known methods can be applied. Examples include composite fibers such as sea-island type polymer array fibers, mixed spun fibers, and various types of split fibers, and polymer array fibers are particularly suitable for the present invention. Its microfiber components include polyester, polyamide, polypropylene, polyethylene, cellulose, etc.
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. Using these microfiber-generating fibers, processes such as liquid bath, steam or dry heat stretching, crimping, cutting, and opening are performed to produce raw cotton. In this method, all known methods for producing short fibers can be applied. The thickness of the composite fiber after drawing used in the present invention is 0.3
The denier is preferably 10 to 10 denier, particularly preferably 1 to 6 denier, and after ultrafine treatment, the single yarn has a denier of 0.05 denier or less, preferably 0.02 denier or less. In the present invention, the thinner the fibers are, the more advantageous it is to make the artificial leather product thinner and softer. A nonwoven fabric sheet in which composite fibers are three-dimensionally entangled is made using such raw cotton, and the method is to needle-punch a single-layer or multi-layer web obtained by a known method such as carding, cross-wrapping, or random wetting. and convert it into a sheet. The needle density in the needle punch may be selected depending on the purpose and use of the artificial leather, but is preferably 200 to 7000 needles/cm ² .
Such needle punching may be performed after applying a lubricant before and/or during sheet formation for the purpose of reducing needle resistance or increasing sheet density. The apparent density of the nonwoven fabric sheet formed by needle punching must be 0.18 g/cm ³ or more, preferably 0.20 g/cm ³ or more. Needle punching is a process performed to entangle composite fibers, and the subsequent microfine treatment causes entanglement of the resulting fiber bundles. After being formed into a sheet by needle punching, the nonwoven fabric sheet is subjected to high-speed fluid treatment to destroy some of the composite fibers to expose the single fibers, and to entangle some of the single fibers with the composite fibers and/or single fibers. . The process of applying a high-speed fluid treatment to the nonwoven fabric sheet after forming a nonwoven fabric sheet with an apparent density of 0.18 g/cm ³ or more through a series of processes, that is, a needle punching process, is a process of high quality. In addition, it has a high-quality surface and synergistically brings about particularly important effects in producing ultra-thin artificial leather. This effect will be explained in detail later. Moreover, this is thought to be due to the compressive action occurring at the same time as the intertwining of the single fibers progresses during the high-speed fluid treatment, but the effect of further reducing the thickness of the nonwoven fabric sheet can be obtained. That is, by this treatment, the thickness of the nonwoven fabric sheet can be reduced by 10% or more. The method of high-speed fluid treatment 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 narrow orifice as a high-speed jet flow, is common, and the present invention This method is suitable for
In this case, the orifice diameter used is 0.05 to 1.00 mm, preferably 0.05 to 0.5 mm. The pressure to push out water is generally 10-500Kg/ ^cm2 , preferably 30-300Kg/cm2
Kg/cm ² is adopted. This spraying treatment is preferably carried out repeatedly from both the front and back sides of the nonwoven fabric sheet while swinging the orifice. If the ratio of broken conjugate fibers to all conjugate fibers in a nonwoven fabric sheet by high-speed fluid treatment is too low, it will be difficult to achieve the effect of thinning the sheet and increasing the apparent density, which is the objective of the present invention. If it is too high, the quality of the nap will deteriorate or the texture will become too hard, so the generally preferred range is 0.5% to 20%. More preferably it is 1 to 15%.
The depth into the sheet to which the treatment is applied is preferably about 1/2 or more of the thickness of the sheet, and when treating both sides of the sheet, it is preferably about 1/4 or more of the thickness of the sheet. The proportion of composite fibers destroyed by the treatment at this time is determined by measuring the weight, and calculated using the following formula. {1-(Weight of unbroken conjugate fiber)/(Total weight)}×100 The depth within the sheet where the effect of the treatment reaches is determined from a cross-sectional photograph taken with a scanning electron microscope. The series of processing as described above, that is, first, a nonwoven fabric sheet with an apparent density of 0.18 g/cm ³ or more is formed by needle punching, and then a high-speed fluid treatment is applied to the nonwoven fabric sheet. , which synergistically brings about important effects in producing ultra-thin artificial leather with high quality and high quality surface, will be explained in detail below. That is, in the method of the present invention, after forming a web using a composite fiber that generates ultrafine fibers of 0.05 denier or less, which are much thinner than conventional ultrafine fibers, the web is first subjected to a needle punching treatment to form the composite fiber. apparent density of intertwined fibers
A high-density nonwoven fabric sheet with a density of 0.18 g/cm ³ or more, for example, an entangled structure of fiber bundles made up of 100 or more, preferably more than 200 single fibers (hereinafter referred to as fiber bundle entanglement). ) is formed. Next, this nonwoven fabric sheet is subjected to high-speed fluid treatment, so that in the portion near the surface layer of the nonwoven fabric sheet, the composite fibers become fibrillated due to the above-mentioned destruction, and the single fibers exposed from the composite fibers are bonded to each other. A layer is formed in which the composite fibers are intertwined with each other (hereinafter referred to as single fiber entanglement), and further inside the layer, single fibers are mixed and entangled with composite fibers (hereinafter referred to as fiber bundle/single fiber entanglement). form,
Further, inside the fiber bundle, a layer is formed in which the fiber bundles are entangled with each other. In other words, such nonwoven fabric sheets can be roughly divided into three different structures in the thickness direction from the surface side: single fiber entanglement, fiber bundle/single fiber entanglement, and fiber bundle entanglement within the same nonwoven fabric sheet. It will have a mixture of. After making such a unique nonwoven sheet,
As described below, by further performing the microfine treatment, application of a binder, and buffing processes, the high-density intertwined single fiber portion in the surface layer is
It has a dense and elegant nap made of ultra-fine fibers of 0.05 denier or less, and has the effect of thinning the nonwoven fabric sheet and imparts excellent mechanical performance. Since it has a nonwoven structure with fiber bundle entanglement, this part is flexible and has good drapability and mechanical performance. That is, to explain in more detail, by using ultra-fine fibers of 0.05 denier or less, more preferably 0.02 denier or less, in addition to obtaining a surface quality with a luxurious feel, the important point of the present invention is to obtain a high-density sheet. , it becomes possible to obtain an ultra-thin sheet, which is the intended purpose of the present invention. For example, as described in Example 1 and Comparative Example 2 below, when using conventional ultrafine fibers of about 0.1 denier, ultrafine fibers of 0.05 denier or less (in Example 1, thickness: 0.0078 denier, single fiber Number:
223), the single fibers are too thick, making them hard and having a strong repulsive force, and of course the number of single fibers is also small. The disadvantages are that the number of intertwined single fibers is small, they are difficult to intertwine, and the sheet thickness is difficult to reduce. Even if it is obtained, the degree of recovery is low and it is easy to recover, so the effect of reducing the thickness of the sheet, that is, the effect of increasing density cannot be expected much. Furthermore, since the effect of intertwining of the single fibers is not sufficient, even if the thickness of the sheet is made thin, it is impossible to expect a mechanical performance that can be used for practical purposes. Therefore, the thickness of the single fiber to achieve the purpose of the present invention is 0.05 denier or less, preferably
It is important that the fibers be ultra-fine fibers of 0.02 denier or less. Further, the number of single fibers in the cross section of the composite fiber is preferably 100 or more, preferably 200 or more. Needle punch to pre-apparent density 0.18
The reason why the nonwoven fabric sheet has a high density of g/cm ³ or higher is that the structure within the nonwoven fabric sheet is a mixture of the three-layer structure of single fiber entanglement, fiber bundle/single fiber entanglement, and fiber bundle entanglement as described above. In other words, if a high-density nonwoven fabric sheet is made in advance by needle punching, when high-speed fluid treatment is applied, the fluid collides with the surface layer of the nonwoven fabric sheet, fibrillating the composite fibers only in the surface layer and forming single fibers. It ties them together. Since the nonwoven fabric sheet has a high density, the fluid energy is rapidly attenuated by the resistance of the nonwoven fabric sheet, and this effect does not extend to the entire sheet, so that the three-layer structure described above can be created. According to the findings of the present inventors, the three-layer structure described above cannot be produced by the following methods other than the method of the present invention. That is, for example, when a web that is already made of ultra-fine single fibers is needle-punched, the treatment marks are noticeable and dirty, and when such a nonwoven fabric sheet is subjected to high-speed fluid treatment, the entire nonwoven fabric sheet becomes entangled with single fibers. This results in a paper-like texture, and the object of the present invention cannot be achieved. In the case of webs using composite fibers, needle-punched nonwoven fabric sheets have an apparent density of 0.18 g/cm ³
If the density is less than that, if the nonwoven fabric sheet is treated with a high-pressure jet stream that is high enough to fibrillate the composite fibers, the entire nonwoven fabric sheet becomes entangled with single fibers, giving it a paper-like feel. On the other hand, when high-speed fluid treatment is applied at low pressure, the composite fibers on the surface layer of the nonwoven sheet cannot be sufficiently fibrillated, and unfibrillated fiber bundles are exposed, resulting in a decrease in surface quality, which is undesirable. The treatment does not have a sufficient effect of increasing the density of the entire sheet, and the aim of the present invention cannot be achieved. In contrast to these similar technologies, in the present invention, the sheet can be made into a nonwoven fabric sheet with a roughly three-layer structure, and for the first time, a layer that contributes to surface quality, a layer that contributes to mechanical performance such as strength, and a layer that contributes to flexibility. As mentioned above, the effect can be shared between each layer, and even though it is extremely thin, by applying the specified high-order processing described later, it can achieve sufficient quality and dignity. Basically, it is possible to obtain an artificial leather having a non-woven fabric sheet. The unique effects of the combination of needle punch processing and high-speed fluid processing are roughly as explained above. After performing the high-speed fluid treatment as described above, the nonwoven fabric sheet is heat-shrinked by wet and/or dry methods to form a high-density sheet. Thereafter, ultrafine treatment is performed using a heat-shrinkable high-density nonwoven fabric sheet to generate ultrafine fibers. For splittable composite fibers, this ultra-fine treatment is achieved through physical and chemical treatment.
In the case of conjugate fibers in which ultrafine fibers become apparent by removing components, a method such as removing unnecessary portions with a solvent may be used. In some cases, such ultra-fine treatment may be performed after previously applying a shape fixing agent such as polyvinyl alcohol to facilitate processing. This shape fixing agent may be removed when shape fixation is no longer necessary. Next, the sheet is impregnated with a polymeric elastomer to produce a composite sheet. As the polymeric elastomer used in the present invention, for example, one or more of synthetic rubbers such as polyurethanes, polybutadiene, polyisoprene, polychloroprene, and polyacrylic rubbers, or natural rubbers are used. Among them, polyurethanes are suitable polymeric elastomers. This polymeric elastomer is used in the form of a solution, emulsion, dispersion, or the like. After a nonwoven fabric sheet is impregnated with a polymeric elastomer, it is wet and/or dry coagulated to produce a composite sheet. This combination of treatments allows for extremely thin,
A high-density composite sheet is obtained. Normally, when sheets are made thinner by pressing, etc., there are problems such as the texture becoming paper-like or the thickness recovering in later processes, but this process does not have these problems. It is a characteristic. Next, the surface of the composite sheet is subjected to a nap-forming treatment to form naps on the surface. Means for forming the nap include sandpaper, sand cloth, sand net, steel brush, garnet, etc. Among them, the use of sandpaper to form the nap is common. Since such a raised sheet is obtained from a high-density composite sheet, it can have a finer and more luxurious surface quality than conventional artificial leather. In the process before and after obtaining the raised sheet, depending on the purpose and use, further heat treatment, dyeing, silver surface imparting, etc.
By performing a known additional process such as slicing, it is possible to process the product into suede-like artificial leather with raised naps that is thinner than conventional artificial leather, or silver-finished artificial leather with a silver surface. In this way, the obtained artificial leather has ultrafine fibers that are highly dense and highly entangled. Therefore, by appropriately selecting the basis weight of the nonwoven fabric, it is possible to obtain an artificial leather based on a nonwoven fabric that has not been obtained to date. This makes it possible to create extremely thin products with a thickness of 0.50 mm or less. Moreover, the obtained artificial leather has mechanical performance comparable to that of conventional thick artificial leather. In addition, this artificial leather is extremely flexible and has excellent drapability, so it is suitable for thin clothing materials such as dresses, blouses, and shirts. (Effects of the present invention) According to the present invention, the following effects can be obtained. (1) Extremely thin artificial leather can be obtained. (2) High-density artificial leather can be obtained. (3) Detailed and high-quality surface quality can be obtained. (4) Artificial leather with excellent mechanical performance can be obtained. (5) Artificial leather that is flexible and has good drapability 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. (1) Tensile strength: JIS-L1079 5, 12, 1 (2) Tear strength: JIS-L1079 5, 14 C method (3) Bending strength: JIS-L1079 5, 17 A method (4 ) Drape coefficient: JIS-1079 5, 17 F method Note that all percentages and proportions in the examples are based on weight. Example 1 The island component is polyethylene tereftate, the sea component is polystyrene, and the ratio of the island component to the sea component is
A web with a fabric weight of 620 g/m ² was created using a polymer array fiber with a ratio of 223 Shimamoto fibers, a thickness of 3.5 denier, a cut length of 51 mm, and a number of crimps of 15 to 18 crimps/inch at a ratio of 50:50 through a card and a cross wrapper. did. The web was needle punched with a needle density of 3500 needles/cm ² to form a nonwoven fabric sheet with a basis weight of 595 g/m ² and an apparent density of 0.233 g/cm ³ , and then an orifice diameter of 0.20 mm was punched.
Waterjet punching was performed once on each of the front and back sides of the nonwoven fabric sheet at a pressure of 1.0 mm, a water pressure of 100 Kg/cm ² , a swing width of 10 mm, a swing cycle of 3 times/second, and a processing speed of 25 cm/minute. The basis weight of the nonwoven fabric sheet at this time was 595g/m ² ,
The apparent density is 0.284 g/cm ³ , and the percentage of broken conjugate fibers according to the measurement method described above is 10.7%, and the conjugate fibers are broken to a depth of about 1/3 from both the front and back sides of the sheet. was recognized. Thereafter, the sheet was immersed in hot water at 90° C. for 3 minutes to shrink. The area shrinkage rate at this time was 23.0%. After immersing this sheet in a 12% aqueous solution of polyvinyl alcohol, a squeezing operation was performed to reduce the fibers to 100%.
38.6 parts of polyvinyl alcohol was applied to each part. Next, it was immersed in trichlorethylene to remove sea components, and then impregnated with 10% dimethylformamide of polyurethane, wet coagulated, and polyvinyl alcohol and dimethylformamide were removed by washing with hot water. The amount of polyurethane deposited by this impregnation was 12.6 parts per 100 parts of fiber.
The apparent density of fibers in this composite sheet is 0.439
g/cm ³ , and the apparent density of the composite sheet was 0.494 g/cm ³ , which was extremely high density compared to conventional sheets. Next, this composite sheet was sliced in the plane direction to obtain two composite sheets. After that, the composite sheet was subjected to a buffing machine to form a nap to form a nap sheet, and then jet dyed using a disperse dye at 120°C for 60 minutes.
Thickness 0.40mm, area weight 165g/m ² , apparent density 0.413g/
cm ³ suede-like artificial leather was obtained. The obtained artificial leather was extremely thin, flexible and drapeable compared to conventional leather, and had excellent mechanical performance, making it suitable as a thin material. Comparative Example 1 A needle-punched nonwoven fabric made of the polymer array fibers of Example 1 was immersed in hot water at 90° C. for 3 minutes to shrink in hot water. The area shrinkage rate at this time was 19.2%. This shrink sheet was impregnated with a 12% aqueous solution of polyvinyl alcohol, so that 61.5% polyvinyl alcohol was adhered to 100 parts of fiber. It was then immersed in trichlorethylene to remove sea components, then impregnated with a 10% polyurethane solution in dimethylformamide, wet coagulated, and the polyvinyl alcohol and dimethylformamide were washed with hot water. The amount of adhesion due to this impregnation is
The ratio was 26.7 parts to 100 parts of polyurethane. The apparent density of fibers in this composite sheet is 0.303
g/cm ² , the apparent density of the composite sheet is 0.384,
This was considerably denser than the conventional one. Next, this composite sheet is sliced in the plane direction into 2 pieces.
It was made into two composite sheets. Thereafter, the composite sheet was subjected to a buffing machine to form a nap to form a nap sheet, and then jet dyed using a disperse dye at 120°C for 60 minutes.
Thickness 0.56mm, area weight 186g/m ² , apparent density 0.332g/
cm ³ suede-like artificial leather was obtained. The obtained artificial leather is quite thin, flexible, and has excellent mechanical performance, but it is thicker than that of Example 1.
The apparent density was also low, and was of an insufficient level as a thin material. Comparative Example 2 The island component is polyethylene terephthalate, the sea component is polystyrene, and the ratio of the island component to the sea component is
The same treatment as in Example 1 was performed using a polymer array fiber having a ratio of 50:50, a Shimamoto number of 16, a thickness of 3.5 denier, a cut length of 51 mm, and a number of crimps of 15 to 18 crimps/inch. The artificial leather obtained by this method has a thickness of 0.75
It has an apparent density of 0.265 g/cm ³ and a basis weight of 199 g/m ² , and these properties are almost the same as those of artificial leather processed using conventional technology that does not undergo water jet punching, and it also has excellent resilience. It had a strong texture and was not suitable as a thin clothing material in terms of sensory performance. Next, Examples, Comparative Examples, and Comparative Example 2 according to the present invention
Table 1 shows the physical properties of a conventional product made of fibers without waterjet punching. 【table】

Claims (1)

[Scope of Claims] 1. A web made of composite fibers that mainly generate ultrafine fibers of 0.05 denier or less is needle-punched to form a nonwoven fabric sheet with an apparent density of 0.18 g/cm ³ or more, and then a high-speed fluid is applied to the nonwoven fabric sheet. 1. A method for producing ultra-thin artificial leather, the method comprising: processing the conjugate fibers, and then subjecting the composite fibers to a combination of the following steps: ultra-fine fineness, application of a binder, and buffing. 2. The method for producing ultra-thin artificial leather according to claim 1, wherein the thickness of the artificial leather is 0.50 mm or less. 3. The method for producing ultra-thin artificial leather according to claim 1, wherein the artificial leather has an apparent density of 0.35 g/cm ³ or more.