JPH0651953B2 - Nubuck-like artificial leather - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention has a high-quality nubuck-like surface appearance with short and dense naps, a soft texture, and excellent wrinkle resistance and abrasion resistance, and is suitable for clothing applications. It is about leather.

[0002]

2. Description of the Related Art Conventionally, several artificial leathers obtained by interposing a rubber-like elastic polymer in an entangled nonwoven fabric of ultrafine fibers and raising the surface thereof have been developed and have been well received. In recent years, diversification of varieties of artificial leather has been required, and in contrast to long-haired suede-like leather, a nubuck-like artificial leather with short and short naps and a higher quality is strongly desired. ing.

The inventors of the present invention previously disclosed in Japanese Patent Laid-Open No. 53-3186.
No. 6 and No. 53-65471 propose a nubuck-like artificial leather using ultrafine fibers obtained by the melt blow method. These have good quality and characteristics, but in order to make the texture more soft, for example, if the filling amount of the rubber-like elastic polymer interposed in the fiber gap is reduced, the napped hair of the surface nap becomes long. It has been found that there are problems such as a rough surface, a decrease in wrinkle resistance, and a decrease in the wear strength of the surface.

On the other hand, in Japanese Patent Publication No. 48-32302, a non-woven fabric mainly composed of polymer arrays is impregnated with a polymer substance from one side of the non-woven fabric so as to generate a density distribution in the thickness direction of the sheet, or the non-woven fabric. There is disclosed a method for producing a napped sheet in which a polymer material is impregnated from both sides of the sheet, and the obtained sheet is sliced at the central portion to nap the surface. However, this method mainly requires the use of a high-viscosity solution of the polymer substance to be impregnated or the impregnation of the polymer substance solution from only one side of the sheet, so the penetration depth of the polymer substance in the thickness direction of the sheet Is difficult to control, and there is a problem that quality variation is likely to occur, and impregnation unevenness may occur in some cases. Further, when this method is applied to an ultrafine fiber sheet, the above-mentioned problem becomes more prominent because the three-dimensional entangled body of ultrafine fibers obtained by the melt blow method has a high bulk density. Further, the above method has a problem in productivity and cost because it requires a slicing step. Moreover, since the polymer array fiber is used, it is necessary to extract the sea component to make it into ultrafine fibers, which does not result in a high-density nonwoven fabric, which naturally limits the napped density and provides a nubuck-like surface. I can't.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to solve all the problems of the prior art described above, and to obtain a high-quality super nubuck-like surface effect (having short fluff but fine nap, which is elegant. It is to provide a new raised artificial leather which has a choke mark property), is excellent in flexibility, wrinkle resistance and abrasion resistance and is suitable for clothing.

[0006]

The above objects of the present invention are as follows:
Average fiber diameter obtained by melt blow method: 0.1 to 6.0 μ
m a plurality of ultrafine fibers are entwined with each other three-dimensionally and at least one surface (A) includes a nonwoven fabric layer, and a rubber-like elastic weight impregnated in a tissue gap of the fiber sheet. And the weight distribution amount of the rubber-like elastic polymer in the area on the front surface (A) side of the fiber sheet is 1.2 times or more that of the area on the back surface (B) side, and the front surface (A) Achieved by a nubuck-like artificial leather characterized by napped microfibers on the side.

The melt-blowing method is based on Industrial
and Engineering Chemistry
48 (8), 1956, JP-A-50-46972, JP-A-53-34218, and the like. A molten polymer is discharged from a spinneret, and the molten polymer is drawn by a high-temperature and high-speed gas stream. It is a process of directly forming ultrafine fibers into a web. As the polymer used in the melt-blowing method, any polymer can be applied as long as it has thermoplasticity, and examples thereof include polyester, polyamide, polyacrylonitrile, polyolefin and the like. Polyester, particularly polyethylene terephthalate, is preferred for obtaining fibers having high heat shrinkability. In the melt blow method, the ultrafine fiber web having an average fiber diameter of 0.1 to 6.0 μm of the present invention can be obtained by changing the discharge amount of molten polymer, the gas temperature, the gas flow rate and the like. Further, it is difficult to measure the fiber length because the diameter of the fiber manufactured by the melt blow method is extremely small, but the average fiber length is 3
cm or more, usually 10 to 30 cm.

The ultrafine fiber web obtained by the melt-blowing method is a random web in which ultrafine fibers are not substantially bundled. Depending on the blow conditions, small rope-shaped fibers (fine fibers are bundled) may occur,
The amount of this rope-shaped fiber generated is extremely small. Since the present invention has a random structure in which ultrafine fibers are not substantially bundled, a nonwoven fabric having a high fiber density can be obtained as compared with a conventional nonwoven fabric mainly composed of polymer arrays (mainly composed of ultrafine fiber bundles). To be Therefore, when the surface of the non-woven fabric is raised, in contrast to the conventional fiber bundle-like rough naps (suede-like naps), the present invention produces highly fine single-fiber naps that are not substantially bundled. Therefore, an elegant surface effect (choke mark property) can be obtained even if the nap length is extremely short, 0.5 mm or less. This is the first point where a nubuck-like surface can be obtained.

Further, the melt-blown ultrafine fibers have a fiber diameter distribution which is close to a normal distribution. For example, the standard deviation of fibers having an average fiber diameter of 2.0 μm is about 1.6 μm.
It is considered that by mixing the fibers having such a fiber diameter distribution, the fluff density of the napped layer obtained is further increased, and the preferable surface effect is strengthened. The web obtained by the melt-blowing method generally has high heat shrinkability. Particularly in the case of a melt blown polyethylene terephthalate fiber web, the boiling water area shrinkage is 20 to 80%, and this shrinkage can further increase the napped density of the napped layer,
This is preferable for obtaining a nubuck-like surface.

In the nubuck-like artificial leather of the present invention, it is necessary that the average fiber diameter of the ultrafine fibers is 0.1 to 6.0 μm. The artificial leather obtained when the average fiber diameter exceeds 6.0 μm can be used for suede-like leather having long naps, but especially when the nap length is 0.5 mm or less, chalk of the nap layer is obtained. The markability is remarkably inferior and the surface feel becomes rough, so that the nubuck-like surface in the present invention cannot be obtained. On the other hand, when the average fiber diameter is 0.1 μm or less, the strength of the naps obtained is poor and the dyeability is remarkably poor, which is not suitable for practical use. That is, 0.1 to 6.0
For the first time with an average fiber length of μm, a graceful surface effect (choke mark property) even with a short nap length of 0.5 mm or less
The surface feeling and the high-grade nubuck skin surface are achieved, and this is the second point of the present invention.

The average fiber diameter is measured by the following method. Any one of non-woven web or artificial leather sample
An electron microscope (made by JEOL, JSM-T30
0) is used to take 10 photographs at a magnification of 1000 times (2000 times when the average fiber diameter is less than 1 μm). The diameter of any 20 fibers is measured per photograph and this is done for 10 photographs. A total of 200 fiber diameter measurement values are obtained and the average value is calculated to obtain the average fiber diameter.

In a web formed by accumulating ultrafine fibers obtained by the melt-blowing method on a moving net conveyor, two-dimensional entanglement of the fibers is recognized, but the degree of fiber entanglement in the web thickness direction. However, there is no so-called tertiary confounding. By increasing the degree of fiber entanglement of the meltblown web and performing tertiary entanglement of the ultrafine fibers, the strength of the ultrafine fiber nonwoven fabric is increased, the nonwoven fabric is made more flexible, and the napped density is increased when the surface is raised.

In order to entangle the ultrafine fibers with each other three-dimensionally, there are a method of spraying a high-speed liquid stream on the surface of the melt blown web, a needle punching method and the like. To form a high-speed liquid flow, use an orifice of 0.1 to 0.3 mmφ
100 kg / cm ^2, preferably by injecting water at a pressure of 10~60kg / cm ² to form a columnar flow of water. In this liquid flow treatment, it is preferable to spray the liquid uniformly on the web surface in order to improve the smoothness of the surface. During this liquid flow treatment, in order to drain the liquid to the surface opposite to the spraying surface, -50 to -25
It is preferable to carry out the suction treatment at a reduced pressure of 0 mmHg because the fibers are more efficiently entangled and the traces of the liquid flow path are hardly left on the surface. Performing the sprinkling flow treatment after the straight-moving flow treatment is even more preferable, because the traces of the flow passage of the straight-moving flow can be erased by the sprinkling flow to improve the surface smoothness. As the sprinkling flow, a sprinkling type nozzle is used, or a method of spraying a straight flow to a wire net or the like to sprinkle the liquid flow is used.

In the needle punching method, it is not preferable to treat the ultrafine fiber web only with the needles having the usual barbs because the resulting web has needle holes and the fibers are not efficiently entangled. Therefore, it is preferable to use a fine needle or a needle without barb. However, if the fibers are entangled sufficiently with only the needle, needle holes are left in the obtained web, the fibers are severely cut, and the obtained web strength is lowered. From this point, the fiber entanglement by the above-mentioned high-speed liquid flow treatment is preferable. In addition, first performing needle punching as a preliminary fiber entanglement step, and then performing a two-step process of performing full-scale fiber entanglement with a high-speed liquid flow,
It is more preferable because the entanglement efficiency of the high-speed liquid flow treatment is enhanced, and a smooth surface can be obtained without leaving needle holes in the obtained web.

The fiber sheet used in the nubuck-like artificial leather of the present invention may be any fiber sheet as long as it has at least one surface covered with ultrafine fibers obtained by the melt blow method. That is, it is possible to use a three-dimensional entangled body composed only of melt-blown ultrafine fibers, or a fiber sheet in which a woven fabric, a knitted fabric, or another non-woven fabric is integrated by entanglement of fibers with each other on the inner layer or the back surface thereof. Of course, it may be an entangled fiber sheet formed by combining a melt-blown ultrafine fiber entangled body with a knitted fabric or another non-woven fabric.
In particular, it is preferable to use a knitted or woven fabric for the inner layer or the back layer because the clothing properties such as tensile strength, tear strength and seam strength are significantly improved. Such a laminated entangled structure fibrous sheet can be easily obtained by laminating a melt blown web, a woven fabric, another non-woven fabric, and the like, and then performing an entanglement treatment.

The entangled fiber sheet of the present invention has a non-woven fabric layer in which at least one surface of melt-blown ultrafine fibers is three-dimensionally intertwined with each other. This non-woven fabric layer has a structure in which ultrafine fibers separated from each other in the form of single fibers are intertwined with each other, and is not a entangled structure of fiber bundles such as those obtained from fibers made of polymer mutual array. Due to such a non-woven fabric structure, the fiber density of the non-woven fabric layer is increased, and the napped density is significantly increased when the surface is raised. This achieves an unprecedented excellent surface effect.

In order to obtain the nubuck-like artificial leather of the present invention, the fiber sheet obtained as described above has the surface (A) side on which at least the nonwoven fabric layer of ultrafine fibers obtained by the melt-blowing method is arranged. It is necessary to impregnate the rubber-like elastic polymer so that the weight distribution of the rubber-like elastic polymer is 1.2 times or more than that of the opposite side (B) side. Several methods can be used to apply more rubber-like elastic polymer to the surface (A) side of the fiber sheet as described above, but a method using migration of a sizing agent is preferable as shown below. Is. That is, the sizing agent solution is impregnated before applying the rubbery elastic polymer to the fiber sheet. As the impregnating paste agent, polyvinyl alcohol, carboxymethyl cellulose (Na salt), starch,
An aqueous solution of polyacrylamide, polyacrylic acid (ammonium salt) or the like can be used. However, polyvinyl alcohol is preferable because it is easy to stably control migration (a phenomenon in which the migration of the sizing agent occurs in the thickness direction of the sheet during drying and causes an uneven distribution).

For drying, a hot air dryer of a type in which hot air is blown onto the surface of the sheet is preferably used. This type of dryer blows out hot air from a slit-shaped nozzle, sprays it onto both the front and back sides of the object to be dried (fiber sheet), circulates this hot air in the drying box, and discharges some hot air out of the box. By this, the temperature and humidity inside the box are controlled. Generally, when a fibrous sheet is impregnated with a sizing agent aqueous solution and dried with a hot air dryer, the sizing agent spontaneously migrates. This migration state is
A large amount of sizing agent is distributed in the front surface layer and the back surface layer (almost the same amount of sizing agent is distributed in the front surface layer and the back surface layer) when viewed in the thickness direction of the sheet, and an extremely small amount of sizing agent is distributed in the intermediate layer. Absent. The distribution state of the sizing agent can be found by observing the cross section of the sheet with a microscope. When a fibrous sheet in which the sizing agent migrates to both surfaces in this way is impregnated by making a solution of a rubber-like elastic polymer such as polyurethane in a solution and solidifying, the rubber-like elastic polymer is mostly present in the intermediate layer of the sheet with a small sizing agent distribution. It is distributed, and only a small amount is distributed on the front surface and the back surface of the sheet having a large distribution of the sizing agent.

On the other hand, in order to obtain the nubuck-like artificial leather of the present invention, the amount of sizing agent is large on the back surface (B) side and the front surface (A).
Dry so that it is less distributed on the side. The distribution ratio of the sizing agent is preferably 1.2 or more, and more preferably 1.5 or more, by weight ratio on the back surface (B) side than on the front surface (A) side. The distribution ratio of the sizing agent is obtained by slicing the sheet to which the sizing agent is attached at the center, dividing the sheet into two equal parts in the thickness direction, extracting the sizing agent from each sheet, and measuring the weight.
The drying method for causing migration toward the back surface (B) side is achieved by setting the drying speed on the back surface (B) side to be higher than that on the front surface side. When a hot air dryer is used, the air volume, temperature or humidity on the back surface (B) side is set to be higher than that on the front surface (A) side. As a method of making the air volume on the back surface (B) side larger than that on the front surface (A) side,
A method in which the blowing speed of the hot air from the back surface (B) side blowing nozzle is made larger than that in the front surface (A) side, a method in which the opening area of the back surface (B) side blowing nozzle is made larger than that in the front surface (A) side, or It is possible to use a method in which the number of blowing nozzles on the back surface (B) side is larger than the number on the front surface (A) side among the large number of blowing nozzles. Of course, a method in which hot air is not blown to the front surface (A) side only and only the back surface (B) side is blown is also possible. In this case, migration of the adhesive agent to the back surface (B) side is most remarkable. . The ratio of the amount of hot air (mass velocity of hot air per 1 m ^{2 of} sheet surface) on the back surface (B) side and the surface (A) side is 1.5 or more,
It is preferably 2.0 or more, and more preferably 3.0 or more. As a method of making the temperature on the back surface (B) side higher than that on the front surface (A) side, it is preferable to make the temperature of the hot air from the blowout nozzle to the back surface (B) side higher than that on the front surface side. The temperature of the hot air to the back surface (B) side is higher than that to the front surface (A) side by at least 10 ° C. or higher, preferably 30 ° C. or higher, and more preferably 50 ° C. or higher. As a method for making the humidity on the back surface (B) side higher than that on the front surface (A) side, the amount of exhaust of the hot air on the back surface (B) side to the outside of the drying box is a factor other than the air flow rate and temperature of the hot air described above. Is larger than the surface (A) side. Of these migration methods to the back surface (B) side, the method using the air volume of hot air is the most preferable in terms of the sizing agent migration state, drying efficiency and production stability (reproducibility, cost).

After the sizing agent is attached to the fiber sheet and dried, a rubber-like elastic material such as polyurethane is impregnated into this fiber sheet, and then the sizing agent solvent (generally water) is used to extract and remove most of the sizing agent. . After that, the surface of the sheet is raised with sandpaper or the like. Before or after the raising, if necessary, the fiber sheet is subjected to a dyeing and finishing process to obtain the nubuck-like artificial leather of the present invention.

In the nubuck-like artificial leather of the present invention thus obtained, the rubber-like elastic polymer is mainly distributed on the surface (A) side where the distribution amount of the sizing agent is small, and the back surface where the distribution amount of the sizing agent is large. Less rubber-like elastic polymer is distributed on the (B) side. Therefore, on the surface (A) side, extremely dense naps are formed due to the binder effect of the rubber-like elastic polymer, and the surface touch becomes moist, giving a texture that is very similar to that of high-quality natural nubuck leather. To be Moreover, the abrasion resistance of the surface is remarkably improved. This is the third point of the present invention. The distribution amount (weight) ratio of the rubber-like elastic polymer was 1.2 on the front surface (A) side with respect to the back surface side.
It is necessary that it is not less than, and preferably not less than 1.5. This ratio can be determined by slicing the sheet after sizing agent extraction and removal into two sheets, and extracting the rubber-like elastic polymer from each sheet with the solvent. The nubuck-like artificial leather of the present invention thus obtained has a high nap density and a nap length of 0.5 mm.
It is an artificial leather that has an elegant chalk mark property even if it is extremely short, and has a surface feel very similar to that of natural nubuck leather, and high surface abrasion strength that is sufficiently applicable in the field of men's clothing such as coats and blazers. is there.

The nubuck-like artificial leather of the present invention is flexible and has excellent wrinkle resistance and excellent clothing characteristics. That is, the surface effect of the artificial leather can be enhanced by controlling the distribution of the rubber-like elastic polymer in the surface layer in which the distribution amount of the rubber-like elastic polymer is large in the surface layer and small on the back surface side. It became possible to reduce the total filling amount of the elastic polymer, and the drape feeling of the artificial leather was obtained without impairing the surface property.
Moreover, surprisingly, even if the filling amount of the rubber-like elastic polymer is reduced, the wrinkle resistance is less deteriorated.

Further, since the nubuck-like artificial leather of the present invention has a difference in distribution amount of the rubber-like elastic polymer between the front and back surfaces, the front surface is a nubuck-like surface and the back surface is a suede-like surface. It can be used as a different novel artificial leather.

[0024]

EXAMPLES The present invention will be described in more detail with reference to the following examples. Example 1. Polyethylene terephthalate chips were charged into an extruder, melted, and then discharged into a high-speed steam flow at a discharge rate of 0.15 g / min / orifice from 0.3 mmφ orifices arranged in a row at 1500 pitches of 1 mm. The steam was sprayed at a temperature of 360 ° C. and a pressure of 3.0 kg / cm ² G through a slit opened near the polymer discharge orifice. The produced fiber group is continuously accumulated on the moving collection surface located 60 cm below the orifice, and the basis weight is 180 g / m 2.
Rolled up as ² random webs.

The obtained ultrafine fiber web has an average fiber diameter.
Made from ultrafine fibers of 1.5 μm, rope-like fibers are extremely
It was very few. Barb above the web
Needle punch using needle (90 punch / cm²)
Then, place it on a wire mesh and
30kg / cm ²The high-speed water flow ejected at the pressure of G
The entire surface of the web is sprayed thoroughly, and at the same time, -15 is applied to the lower surface of the web.
The fine fibers were entangled with each other by applying suction of 0 mmHg. Next
Then spray a sprinkling flow on it to erase the traces of the high-speed flow,
A smooth nonwoven fabric was obtained.

This nonwoven fabric was dipped in a 4% aqueous solution of polyvinyl alcohol (PVA) and then dried by the following method. For this drying, a pin tenter type hot air drier was used, and hot air of 100 ° C. was blown only on one side and the back side of the sheet. The total amount of PVA attached to the non-woven fabric is 1
It was 5% by weight, and the back side / front side distribution amount ratio of PVA was 5: 1. Next, this nonwoven fabric was dipped in a DMF solution of polyurethane, wet-coagulated in an aqueous solution, and then PVA was extracted and removed with warm water. At this time, the nonwoven fabric shrank by 30% in area. The amount of polyurethane adhered was 60% of the fiber weight. The obtained sheet was sliced at the center to obtain two sheets, polyurethane was extracted from each sheet with a DMF solvent, and the weight distribution ratio of the front surface / back surface polyurethane was 3.2. . The front and back surfaces of the obtained sheet were buffed with 250 mesh sandpaper, and dyed and brushed. When the surface of the obtained raised artificial leather was observed with a microscope, the average fiber diameter was 1.5 μm and the average nap length was 0.2 mm.
The ultrafine fluff consisting of was generated at a high density. Despite its short fluff, this surface showed an elegant chalk mark and had a moist surface touch, which was of a surface quality very similar to that of high-quality natural nubuck leather. In addition, this artificial leather is flexible (softness of 40 mm according to the cantilever method) and has 82% wrinkle resistance (wire method).
And was good. Further, the abrasion resistance of the surface of this artificial leather was extremely good showing the performance of 50,000 times or more by the Martindale method.

For comparison, the napped artificial leather obtained in the same manner as above except that hot air was blown from the hot air dryer from both sides of the sheet with the same amount of air, and the amount of polyurethane adhered to the surface layer was small, and Long fixation (0.8 m
m) was a napped and rough surface. Moreover, the abrasion resistance measured by the Martindale method was only 20,000 times, which was unsatisfactory.

Example 2. Melt-blown in the same manner as in Example 1 to obtain a random web having a basis weight of 60 g / m ² . A tricot having a basis weight of 40 g / m ² was sandwiched between the two webs to form a three-layer laminated sheet. This laminated sheet was lightly needle-punched by the method described in Example 1 and then entangled with a high-speed water stream to form an integrated nonwoven fabric.

A polyvinyl alcohol aqueous solution was infiltrated and dried on this sheet in the same manner as in Example 1 and then impregnated with polyurethane to obtain a napped artificial leather. The front-side / back-side polyurethane weight distribution ratio obtained in the same manner as in Example 1 was 2.8. The surface of the artificial leather had an elegant nubuck tone, and was excellent in abrasion strength, drape, and clothing properties. In addition, the back surface became semi-suede and a new high-grade artificial leather was obtained.

Example 3. Melt-blown in the same manner as in Example 1 to obtain a random web having a basis weight of 80 g / m ² . Separately, a 0.1 d polyethylene terephthalate ultrafine filament obtained by the melt spinning method was cut into 3 mm and formed into a sheet by a paper making method to obtain a sheet making sheet having a basis weight of 90 g / m ² . A basis weight of 50 between the above meltblown web and this papermaking sheet.
A woven fabric having a relatively rough texture of g / m ² was sandwiched to form a three-layer laminated sheet. This sheet was entangled with a high-speed water stream by the method described in Example 1 to form an integrated non-woven fabric.

After adhering the polyvinyl alcohol aqueous solution to this sheet, using a hot air drier, air is blown from only the back surface (papermaking sheet side) until the moisture content reaches the limit, and then from both sides until the equilibrium water content is reached. And dried. The hot air temperature was 130 ° C. The back side / front side distribution amount ratio of PVA was 3: 1. After that, the same treatment as in Example 1 was performed to obtain a raised artificial leather.

The surface of this artificial leather is short (0.5 mm)
It was a nubuck-like material with high density of raised hair and excellent choke mark properties. Long backs (1.0m
m) Suede style. Further, it was excellent in drape property and clothing property, and was also good in surface abrasion strength. The weight distribution ratio of the polyurethane on the front side / back side of the artificial leather of Example 3 was 1.5.

Example 4. Melt blow nylon 6
A random web having an average fiber diameter of 3 μm and a basis weight of 300 g / mm ² was obtained. This was entangled with a high-speed water stream, an aqueous solution of carboxymethyl cellulose (Na salt) was attached, and then dried with a hot air dryer. As the drying conditions, the hot air temperature on the front surface side was 50 ° C. and the back surface side was 130 ° C. After that, the same treatment as in Example 1 was performed to obtain a raised artificial leather. This artificial leather has a good nubuck-like surface,
The flexibility was good. The weight distribution ratio of the polyurethane on the front surface side / back surface side of the artificial leather of Example 4 was 2.3.

[0034]

Since the artificial leather of the present invention is constructed as described above, it has a nubuck-like surface effect and is excellent in flexibility, wrinkle resistance, and abrasion resistance, and is a high-quality raised fabric for various clothing applications and the like. It can be widely used as artificial leather.

Claims (1)

[Claims] 1. At least one surface (A) contains a non-woven fabric layer formed by three-dimensionally intertwining a plurality of ultrafine fibers having an average fiber diameter of 0.1 to 6.0 μm obtained by a melt blow method. And a rubber-like elastic polymer impregnated in the tissue gap of the fiber sheet, and the weight distribution amount of the rubber-like elastic polymer in the area on the front surface (A) side of the fiber sheet is the back surface (B). The nubuck-like artificial leather, which is 1.2 times or more as large as the area on the side, and the ultrafine fibers are napped on the surface (A) side.