JPH0130940B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nonwoven fabric that is flexible and has excellent surface smoothness and is suitable for obtaining, for example, artificial leather that closely resembles natural leather, and a method for producing the same.

Nonwoven fabrics are used, for example, as base materials for artificial leather, and conventional nonwoven fabrics of this type using ultrafine fibers spun by a melt blowing method are known. If this material is used to produce nubuck-like, suede-like, and grain-finished artificial leather, products with excellent surface smoothness, flexibility, and writing effects can be obtained, but most of the stretching is not performed during the fiber forming process of the melt-blowing method. Since there is no material, it is essentially in an unstretched state, and therefore its strength is low, and it has the disadvantage that it cannot be used as a material for clothing, shoes, etc., if used alone.

In order to improve the poor strength of the ultrafine fibers, various measures have been studied, for example, as shown in JP-A-54-122701, a knitted fabric is interposed between the ultrafine fiber entangled layer and the short fiber entangled layer to intertwine and integrate them. A method was proposed. However, although this product has excellent overall strength in the plane direction, the strength in the thickness direction is weak because the knitted fabric and the micro-fine fibers are not sufficiently intertwined, and the micro-fine fibers easily become damaged due to surface abrasion or abrasion. It has the disadvantage of peeling off. Furthermore, due to the brushed microfibers, it has a texture and feel that is very similar to natural leather in appearance, but the knitting structure is exposed in the cross section.
There is a problem that the overall quality is degraded.
In addition, JP-A-54-122701 discloses a structure consisting of an ultrafine fiber entangled layer and a short fiber entangled layer without intervening knitted fabric, but this structure has a low density of fiber entangled bodies. Therefore, it lacks a sense of unity, and is therefore still insufficient to express the feel of natural leather.

In addition, ordinary artificial leather with a silver surface is made of a non-woven fabric mainly made of nylon and/or polyester of 1 to 3 deniers, but even if it is filled with an elastic polymer mainly composed of polyurethane, it does not have the texture of natural leather. You can only get so far. This is because the fiber diameter is too large, so even if needle punching is performed, the density of the intertwined fibers cannot be increased sufficiently, resulting in a lack of unity, and even if heat pressing is performed to increase the density, it will only end up with a so-called paper life. This is not a fundamental solution.

The present inventors have conducted extensive research with the aim of overcoming the drawbacks of conventional nonwoven fabrics and their manufacturing methods and obtaining nonwoven fabrics with excellent appearance, texture, physical properties, etc. A denier short fiber layer and a 0.5 denier or less ultrafine fiber layer spun by melt blowing are laminated, and the laminate is needle punched from both the front and back directions at a rate of 300 to 2000 punches/cm ² to separate the fibers of each layer. The density of the fiber entangled body can be increased by intertwining the fibers of adjacent layers with each other throughout the layer, cutting the ultrafine fibers during needle punching, and filling the voids of the short fibers with the cut ultrafine fibers. The inventors have discovered that this can provide a nonwoven fabric that is highly integrated, flexible, and has a high surface smoothness, and based on this knowledge, the present invention has been completed.

That is, the present invention consists of a laminate of two or more layers of a short fiber layer of 0.5 to 3.0 deniers and an ultrafine fiber layer of 0.5 denier or less spun by a melt blow method, and at least one outermost layer of the laminate is an ultrafine fiber layer. 300 impressions from both the front and back sides of the laminate.
By needle punching at ~2000/ ^cm2 , the fibers of each layer are intertwined with the fibers of the adjacent layer throughout the layer, and the ultrafine fibers cut by needle punching are inserted into the voids of short fibers. Each layer is integrated by being filled, and in the ultrafine fiber layer forming the outermost layer, the fibers of the adjacent short fiber layers are intertwined so that the density sequentially decreases toward the outside. The aim is to provide nonwoven fabrics.

In the present invention, short fiber webs of 0.5 to 3.0 denier can be produced by dry methods such as air lay method and card method.
Alternatively, it can be manufactured by a papermaking method. The basis weight of this short fiber web is preferably 20 to 500 g/m ² . The reason why the thickness of the short fibers is set to 0.5 to 3.0 denier is that if it is less than 0.5 denier, the desired strength cannot be obtained, and if it exceeds 3.0 denier, insufficient density will result.

In the present invention, ultrafine fibers of 0.5 denier or less are produced by a melt-blowing method. The melt-blowing method is a method in which a spinnable polymer in a molten state is pulled by a high-speed gas flow to obtain ultrafine fibers, and since it is a conventionally known method, a detailed explanation thereof will be omitted. The melt blow method was adopted because it is superior in terms of productivity and economy. That is, in addition to the melt-blowing method, methods for producing ultrafine fibers include, for example, the sea-island fiber production method and the split fiber production method, but the former requires a dissolution treatment using a solvent, and the latter requires a split treatment using a chemical. Both are inferior in productivity and disadvantageous in terms of economy.
The basis weight of this ultra-fine fiber web is 500 to 20g/m ²
is preferred. The reason why the thickness of the ultrafine fibers is set to 0.5 denier or less is because if the thickness exceeds 0.5 denier, it is impossible to obtain a fiber with excellent flexibility and surface smoothness.

As materials for the short fibers and ultrafine fibers, for example, polyamide fibers such as nylon 6, polyester fibers such as polyethylene terephthalate, etc. can be used. The short fiber web and the ultrafine fiber web may be made of the same material or may be made of different materials.

In the present invention, the short fiber web and the ultrafine fiber web may have a tangled structure in advance by needle punching or the like, or may not have such a structure. Further, the fibers may be colored in advance with pigments, dyes, etc., and the cross-sectional shape of the fibers is not limited to circular shapes, but can be of various shapes such as triangular and square shapes. Furthermore, it is preferable that the weight ratio of short fibers to ultrafine fibers is in the range of 90:10 to 10:90.

The short fiber layer and the ultrafine fiber layer are laminated adjacent to each other, but this laminate may have two layers, or three or more layers. In this case, at least one outermost layer is made to be an ultrafine fiber layer in order to obtain flexibility, surface smoothness, texture, etc. due to ultrafine fibers.

Next, the laminate is needle punched to intertwine the fibers of each layer. At this time, needle punching is performed so that the fibers of each layer are intertwined with the fibers of the adjacent layer throughout the layer. In order to intertwine the fibers of each layer throughout the layer, needle punching is performed from both the front and back sides of the laminate. It is necessary to do this. Further, during this needle punching, the ultrafine fibers are cut into appropriate lengths, and the cut ultrafine fibers are filled into the voids of the short fibers. Ultrafine fibers have relatively low strength because they are not stretched during production, and therefore, during needle punching, they are cut to a suitable length to fit into the short fiber voids. Due to the synergistic effect of the intertwining of the fibers as described above and the filling of the cut microfibers into the voids of the short fibers, the density of the intertwined fibers becomes extremely high, and the degree of integration of each layer becomes extremely large. , resulting in an extremely rich sense of unity. In order to properly intertwine the fibers and cut the ultra-fine fibers as described above, the number of needle punching strokes is 300 to 300.
It needs to be 2000 times/cm ² . This is because if the number of times is less than 300 times, the entangling will be insufficient, and if the number of times is more than 2,000 times, the ultrafine fibers will be cut excessively and the strength of the tangled fiber product will decrease.

In the present invention, the fiber entangled laminate is further subjected to an elastic polymer impregnation treatment, a napping treatment, and a dyeing treatment, if necessary. The elastic polymer impregnation treatment is a process in which the voids of a tangled body having a laminated structure are filled with an elastic polymer in order to improve strength. Polyurethane elastomer is generally used as the elastic polymer. The napping treatment involves surface grinding using, for example, sandpaper, thereby producing naps with a nubuck-like, velor-like, suede-like, etc. appearance. The dyeing treatment is performed, for example, to reveal a natural leather-like hue.

When manufacturing artificial leather using the nonwoven fabric of the present invention, in order to manufacture each type of leather such as nubuck-like, velor-like, suede-like, etc. , the fiber diameter, (2) the ratio of short fibers to ultrafine fibers, (3) the hardness of the elastic polymer and its adhesion amount, and (4) the degree of surface grinding during the napping treatment, etc., may be selected as appropriate. By doing so, it is possible to easily manufacture a desired type of product.

Since the present invention uses short fibers of 0.5 to 3.0 denier and ultrafine fibers of 0.5 denier or less, both fibers are intertwined very well and ideally (for example, the ultrafine fibers simply enter the short fibers). (The hair of the short fibers also extends into the ultrafine fiber layer, and entanglement occurs here as well), so there is no risk of insufficient entanglement, and therefore there is no risk of the ultrafine fiber layer peeling off from the short fiber layer. Furthermore, during needle punching, the ultrafine fibers are cut into appropriate lengths, and the cut ultrafine fibers are filled into the voids of the short fibers. , the density of the fiber entangled body can be significantly increased, and as a result, a nonwoven fabric with an extremely high sense of unity can be obtained. Further, in the present invention, in the ultrafine fiber layer forming the outermost layer, the fibers of adjacent short fiber layers are intertwined so that the density decreases in the outward direction. For example, in the case of a two-layer structure, after needle punching, the density of short fibers decreases sequentially from the short fiber layer to the ultrafine fiber layer, while the density of the ultrafine fibers decreases sequentially from the ultrafine fiber layer to the short fiber layer, Reinforcement caused by the fibers and density increase caused by the ultrafine fibers occur simultaneously, resulting in a structure and texture that closely resembles natural leather. In other words, by intertwining the short fibers in the ultra-fine fiber layer so that the density decreases as they go outward, the maximum reinforcing effect of the short fibers can be obtained, and the flexibility and surface of the ultra-fine fibers can be improved. A nonwoven fabric with good smoothness, texture, etc. can be obtained. Further, the nonwoven fabric of the present invention has excellent flexibility and surface smoothness, and has high strength because it includes a short fiber layer, unlike a nonwoven fabric consisting only of an ultrafine fiber layer. However, since the nonwoven fabric of the present invention has a high density and a rich sense of unity, when it is used as a base material for artificial leather, it can provide a texture and feel that closely resembles natural leather.

According to the method of the present invention, the appearance and texture as described above,
It has the advantage of being able to produce a nonwoven fabric with excellent physical properties, etc., and is also advantageous in terms of productivity and economy.

Examples of the present invention will be shown below to specifically explain the present invention, but the present invention is not limited thereto.

Example Short fibers made of 6 nylon of 1.5 denier were made to have a basis weight of 150 g/m ² using a random wet bar.
On top of this, 0.01 ~
150g/0.06 denier 6 nylon web
Laminated with a basis weight of m ² , 750 m
Needle punched once/ ^cm2 , thickness 2.0mm
A fiber entangled sheet was obtained. Next, this is mixed into the solid content of a polyurethane elastomer containing polytetramethylene ether glycol as a polyol component.
After being impregnated with a 12.5% dimethylformamide solution, it was coagulated in a non-solvent mainly composed of water, the solvent was removed, and after further washing with water, it was dried in a hot air dryer at 120°C.
A sheet-like material having a fiber:polyurethane ratio of 100:60 was obtained. Next, both sides were raised with 150-mesh sandpaper, resulting in a sheet-like product having nubuck-like naps on the ultrafine fiber side and velor-like naps on the short fiber side. This product was further added with 0.7% Lanyl Brown R (trade name, dye manufactured by Sumitomo Chemical Co., Ltd.) and Lanyl
When this was dyed with 0.15% Black BG e/c (trade name, dye manufactured by Sumitomo Chemical Co., Ltd.) at 95°C to 97°C for 30 minutes, it was extremely flexible and had a smooth surface, with a hue similar to that of natural leather. The product had a good appearance and was suitable for use in shoes, etc.

Comparative example Short fibers made of 6 nylon of 1.5 denier were made to have a basis weight of 300 g/m ² using a random wet bar.
This sheet-like material was subjected to needle-punching treatment, polyurethane elastomer impregnation treatment, napping treatment, and dyeing treatment according to the same method and procedure as in the previous example to obtain a final sheet-like material, which had an extremely unified feel. In addition, it lacked surface smoothness.

Claims (1)

[Claims] 1 A laminate consisting of two or more layers of a short fiber layer of 0.5 to 3.0 deniers and an ultrafine fiber layer of 0.5 denier or less spun by a melt blowing method, at least one outermost layer of the laminate consisting of an ultrafine fiber layer, 300 to 2000 strokes from both the front and back sides of the
By needle punching of ^cm2 , the fibers of each layer are intertwined with the fibers of the adjacent layer throughout the layer, and the cut microfibers cut by needle punching are filled into the voids of the short fibers. A nonwoven fabric characterized in that each layer is integrated, and in the ultrafine fiber layer forming the outermost layer, the fibers of adjacent short fiber layers are intertwined so that the density decreases in the outward direction.