JP3155135B2 - Method for producing nubuck-like artificial leather - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a nubuck-like artificial leather, and more particularly to a method for producing a nubuck-like artificial leather which does not require a two-stage fiber ultra-fine treatment and eliminates a rubber-like appearance and texture. The present invention relates to a method for producing a nubuck-like artificial leather having smoothness, flexibility, sharp chalk mark properties, short hairiness, and excellent homogeneity.

[0002]

2. Description of the Related Art Conventionally, as a method for producing artificial leather having a nap appearance, for example, a fiber assembly such as a woven fabric, a knitted fabric, or a nonwoven fabric is impregnated with a high molecular polymer, solidified, and then the surface thereof is polished. The way has been done.

In order to control the appearance of artificial leather, it is generally practiced to regulate the apparent density of the fiber aggregate, increase the amount of impregnation of the elastic polymer, or control the buff conditions.

However, in these methods, the length of the nap fiber is long, and a good appearance can be obtained as a suede or velor-like artificial leather. However, artificial leather having a nubuck tone with a short fiber length and a high-quality appearance can be obtained. You can't get it.

[0005] In order to solve this problem, as a method of shortening the length of the nap fiber, for example, Japanese Patent Laid-Open No. 3-161576 is disclosed.
In the publication, a first-stage process of expressing ultrafine fibers from the conjugate fibers of the surface layer portion, then applying a polymer elastic body and coagulating, and mainly a second step of ultrafinely forming the conjugate fibers of the inner layer. A method consisting of step-by-step processes has been proposed.

[0006] However, in this method, the process of making the composite fiber ultrafine becomes two steps, the number of steps increases, and the operation becomes complicated. In addition, after the fiber is made ultrafine, an elastic polymer is imparted. There is a problem in that the polymer elastic body is firmly bonded to the ultrafine fibers in the outermost layer, and the appearance and feel are rubber-like.

On the other hand, in Japanese Patent Publication No. 61-32432, a liquid which is a solvent for the elastic polymer and a non-solvent for the fiber is applied to the surface of the suede-like sheet to dissolve a part of the elastic polymer. Alternatively, it has been proposed to re-solidify after swelling and then raise or trim the hair. However, this method aims at preventing the fluff from falling off on the surface of the napped sheet in a fiber napped suede having a long napped surface, and a method for producing a nubuck tone artificial leather as in the present invention. Is completely different.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention provides
Eliminates the need for fine fiber treatment over multiple stages, eliminates rubber-like appearance and texture, has a smooth surface, is flexible, has sharp chalk mark properties, has short bristle feet, and has a uniform nap state. It is an object of the present invention to provide a method for producing good nubuck-like artificial leather.

[0009]

According to the present invention, as means for solving the above problems, at least (a) 2
Forming a web from micronizable composite fibers of at least one high molecular weight polymer;
Needle punching is performed at a barb penetration punching number of 0 to 3000 bars / cm ² to prepare an entangled fibrous base material, and (c) the entangled fibrous base material is impregnated with an elastic polymer and solidified, d) Thereafter, the conjugate fiber constituting the entangled fibrous base material is made extremely fine, and (e) after that, the entangled fibrous base material is sliced in a plane direction and divided into a plurality of pieces, and (f) A liquid containing a solvent of an elastic polymer is applied to the sliced surface of the divided entangled fibrous base material, and after a part of the elastic polymer is dissolved or swelled, the liquid is removed and solidified. , (G)
A method for producing a nubuck-like artificial leather is provided, wherein buffing treatment is performed on the solvent-containing liquid-treated surface of the entangled fibrous base material.

[0010] In the method of the present invention, the ultrafine conjugate fiber is a conjugate fiber formed by composite spinning, mixed spinning, or the like from two or more kinds of high molecular polymers having different properties from each other. Dissolution and removal of high molecular weight polymer,
Alternatively, a material that can be made extremely fine by splitting due to physical or chemical action is used.

In particular, it is preferable to use a composite fiber composed of two or more polymer polymers having different solvent solubilities, and to dissolve and remove at least one of the polymer polymers to make the fibers ultrafine.

In the method of the present invention, specific examples of the polymer forming the ultrafine fibers include polyamides such as nylon 6, nylon 66 and nylon 12, and polyesters such as polyethylene terephthalate and polybutylene terephthalate.

In addition to the above-mentioned polyamide and polyester, the polymer having different properties (for example, solvent solubility) used as a dissolving / removing component and a binding component together with these ultrafine fiber forming polymer is Examples include polyethylene, polypropylene, high molecular weight polyethylene glycol, polystyrene, and polyacrylate.

The conjugate fiber is subjected to a known card, random webber, cross layer, or the like to form a web.

The web thus obtained is needle-punched in the thickness direction of the web in the number of barb-piercing punches of 500 to 3000 bars / cm ² , preferably 800 to 2000 bars / cm ^2. Then, an entangled fibrous base material is prepared. Barb penetration punching number 500 /
If it is less than ² cm ² , the entangled fibrous base material is insufficiently entangled, resulting in insufficient strength and insufficient chalk mark properties of the finished base material. On the other hand, when the number is more than 3000 fibers / cm ² , the entangled fibrous base material is excessively subjected to needle punching, so that the damage is increased and the base material is set, which is not preferable.

Here, the number of barb penetrating punches is
When a needle having at least one barb is used and the barb located at the foremost end is punched at a depth that penetrates in the thickness direction of the web, the number of shots is 1 cm ²
It is a numerical value converted into a value per hit.

The entangled fibrous base material thus prepared by needle punching is impregnated with an elastic polymer and solidified.

Examples of the elastic polymer for impregnating and coagulating the entangled fibrous base material include polyurethane elastomer, polyurea elastomer, polyurethane / polyurea elastomer, polyacrylic resin, acrylonitrile / butadiene elastomer, and styrene / butadiene elastomer. , Among others, polyurethane elastomers,
Polyurethane elastomers such as polyurea elastomers and polyurethane / polyurea elastomers are preferred. These polyurethane elastomers include at least one kind of polymer glycol selected from polyether glycol, polyester glycol, polyester ether glycol, polycaprolactone glycol, polycarbonate glycol and the like having an average molecular weight of 500 to 4,000, and 4,4'- Organic diisocyanates such as diphenylmethane diisocyanate, xylylene diisocyanate, tolylene diisocyanate, dicyclohexyl methane diisocyanate, and isophorone diisocyanate, and low-molecular-weight glycols, diamines, hydrazines,
Alternatively, it is obtained by reacting with a chain extender selected from hydrazine derivatives such as organic acid hydrazide and amino acid hydrazide.

As a method of impregnating and coagulating the entangled fibrous base material with the elastic polymer, the entangled fibrous material may be in the form of an organic solvent solution or dispersion (including an aqueous emulsion). The elastic polymer is solidified in the entangled fibrous substrate by impregnating the substrate. As a specific method for coagulating the elastic polymer, any of a known wet coagulation method and dry coagulation method may be used. In addition, the coagulation state of the elastic polymer in the entangled fibrous base material is preferably solidified in a porous state. A coalescing thin coating layer may be present.

After the entangled fibrous base material is impregnated with the elastic polymer and coagulated, at least one high molecular polymer is dissolved and removed, or the composite is formed by a known method such as splitting by physical or chemical action. Ultrafine fibers. In particular, in the method of the present invention, it is preferable to use a composite fiber composed of two or more polymer polymers having different solvent solubilities, and to dissolve and remove at least one of the polymer polymers to make the polymer ultrafine. .

When the high molecular polymer to be dissolved and removed is a polyamide, a mixed solution of an alkali metal or an alkaline earth metal and a lower alcohol, formic acid or the like is used as a dissolving and removing agent. When the aqueous alkaline solution such as potassium hydroxide or the like is polyethylene, polystyrene, polyacrylate or the like, benzene, toluene, xylene or the like is used.

The average fineness of the ultrafine fibers constituting the entangled fibrous base material after the ultrafine treatment is preferably 0.2 denier or less, particularly preferably 0.1 denier, in order to obtain a uniform and textured surface appearance. It is 1 denier or less.

The entangled fibrous base material made of the ultrafine fibers thus prepared is sliced in a plane direction by a known slicing machine and divided into a plurality of sheets. This sliced surface, the fine fibers are sufficiently entangled by the needle punching, and the slicing step performed here exposes this entangled surface for the first time, so in various steps before the slicing step, The entangled surface is not disturbed and adversely affected. Therefore, a uniform and smooth surface can be obtained very effectively.

The slice plane formed as described above is
It is treated with a liquid containing a solvent for the elastic polymer without any raising treatment. When treated with such a liquid after the raising treatment, the nap fiber length of the finally obtained sheet becomes longer, the nap state of the surface becomes uneven, and the nubuck tone artificial leather aimed at by the present invention cannot be obtained. .

As the liquid containing the solvent for the elastic polymer, a good solvent for the elastic polymer such as dimethylformamide, diethylformamide, dimethylacetamide, tetrahydrofuran or the like, or a mixture of water, alcohol, methyl ethyl ketone and the above-mentioned elastic polymer is used. Those that have been used are preferably used. Since the liquid containing the solvent for these elastic polymers needs to dissolve or swell a part of the elastic polymer, the solvent for the elastic polymer is at least 50% or more.
Preferably, the content is 70% or more.

The method of applying the liquid containing the solvent of the elastic polymer to the sliced surface of the micronized entangled fibrous base material is not particularly limited. For example, application by a gravure coater, spray coater, or mold release A liquid containing a solvent of an elastic polymer is applied to the surface of a support such as paper, and is contacted and integrated with a slice surface of the entangled fibrous base material before drying.
And a method of transferring the liquid. In this step, it is preferable to apply the liquid while gently nipping the substrate with a gravure roll or the like.

Next, in order to remove the liquid containing the solvent of the elastic polymer and to solidify the elastic polymer, a liquid removal treatment is performed. Examples of the liquid removal treatment method include a dry method using a hot air drier, a wet method in which the liquid is immersed in a liquid such as water, and the like, but the dry method reduces the amount of the liquid containing the elastic polymer. It is preferable because it can be performed. Application of this liquid,
The liquid removal treatment is preferably repeated at least 2 to 6 times. As the number of times increases, the homogeneity improves, but when the number exceeds 6, the surface tends to be hardened. The amount of the liquid applied to the slice surface is 5 to 55 g / m ² each time.
It is preferred that If the amount of liquid applied is less than 5 g / m ² , the length of the surface nap fiber becomes longer, making it difficult to obtain the desired nubuck-like artificial leather, and if it exceeds 55 g / m ² , the surface becomes hard or the liquid is removed. It takes time.

By the liquid applying process and the liquid removing process,
After the elastic polymer dissolves or swells, it is re-solidified to increase the bond between the ultrafine fibers and the elastic polymer on the slice surface of the entangled fibrous base material and to hold down the fibers. Has the nature
It is possible to produce an excellent nubuck-like artificial leather having a short hair foot and a uniform piloerection.

Next, the sliced surface of the entangled fibrous base material treated as described above is subjected to buffing treatment. Before the buffing treatment, the sliced surface is smoothed or embossed with a small pattern, a calender roll, a flat plate press or the like. May be processed. Buffing is sandpaper, brush,
It can be performed by a conventional method using a grindstone or the like. However,
Buffing with something too coarse,
When buffing for a long time, the processing surface becomes rough,
Care must be taken since the desired nubuck-like artificial leather cannot be obtained.

[0030]

According to the method of the present invention, 500-3000 pieces / cm ²
Since the fibers are sufficiently entangled by performing needle punching with the number of barb penetrating punches, a substrate having sufficient strength, excellent chalk mark properties, and no damage or sag can be obtained. Furthermore, after performing the ultrafine treatment, the newly formed sliced surface by slicing in the plane direction is treated with the liquid containing the solvent of the elastic polymer as it is, without performing the raising treatment, so that the slice before the slicing step is performed. In various processes, the entangled surface is not disturbed and adversely affected,
In a smooth and homogeneous state, the fibers can be held down by increasing the bond between the microfibers and the elastic polymer on the slice surface, so that the surface is smooth, soft, and has a sharp chalk mark by buffing treatment. Short haired,
It is possible to produce an excellent nubuck-like artificial leather having a uniform napped state.

Further, in the method of the present invention, the ultrafine sizing of the conjugate fiber is performed in one stage, and there is no need for a two-stage ultrafineness treatment.

Moreover, since the conjugate fiber is made extremely fine after the entangled fibrous base material is impregnated with the elastic polymer and coagulated, the conventional technique for applying the elastic polymer after the fiber has been made very fine. In other words, the problem that the elastic polymer is firmly bonded to the ultrafine fibers in the outermost layer at the outermost layer, and the appearance and the feeling become rubber-like can be completely eliminated.

[0033]

The present invention will be described below in detail with reference to examples.

Example 1 Nylon 6 and polyoxyethylene ether-modified low-density polyethylene were mixed at a mixing ratio of 50:
The resulting mixture was chip-blended at 50 and mixed spinning to obtain a conjugate fiber having a fineness of 7 denier and a fiber length of 51 mm. The obtained composite fiber was formed into a web by using a card and a cross layer, and then needle punching was performed at a barb penetration punch number of 1,000 / cm ² to prepare an entangled fiber substrate material of 630 g / m ² .

The entangled fibrous base material is preheated in a hot air oven at 160 ° C., and heated with a 90 ° C. heating roll so that the apparent density becomes 0.29 g / cm ³ and the thickness becomes 2.1 mm. Pressed.

Next, a polybutylene adipate having a molecular weight of 1800 is reacted with polytetramethylene ether glycol having a molecular weight of 2050, 4,4'-diphenylmethane diisocyanate, and ethylene glycol. 5% polyurethane elastomer in dimethylformamide (concentration 15
%) Into the pressed entangled fibrous base material,
It was immersed in a 0% dimethylformamide aqueous solution to coagulate. Thereafter, the substrate was sufficiently washed in warm water at 40 ° C. to obtain a base material impregnated with an elastic polymer having a fiber / polyurethane elastomer ratio of 75:25.

Next, the substrate was repeatedly dipped and nipped in toluene at 80 ° C. to dissolve and remove the polyethylene, thereby making the composite fiber ultrafine. Then, the toluene contained in the substrate was removed in steam at 110 ° C.
It was dried in a hot air dryer at 20 ° C. The average fineness of the obtained ultrafine fibers was 0.01 denier.

After that, the entangled fibrous base material subjected to the ultrafine treatment was sliced in a plane direction and divided into two pieces.

Next, on the slice surface of the divided base material, 2
Using a 00 mesh gravure coater, dimethylformamide was applied at a rate of 9 g / m ² , and the operation of drying and drying was repeated 6 times. Then, the sliced surface was lightly buffed with 400 mesh sandpaper. did.

The sheet thus obtained was a nubuck tone sheet having a very smooth and soft surface, a short nap fiber length, a sharp chalk mark property, and a uniform nap state.

[Example 2] Polyethylene terephthalate and low-density polyethylene were melt-extruded from two extruders at a composition of 50:50, respectively, and were laminated by a composite spinneret into a 48-divided fineness of 4 denier and a fiber length of 51 mm. A hollow splittable conjugate fiber was obtained. The obtained composite fiber was passed through a card and a cross layer to form a web, and needle punching was performed at a barb penetration number of 2,000 / cm ² to prepare an entangled fibrous base material of 400 g / m ² .

After preheating this entangled fibrous base material in a hot air oven at 160 ° C., a 90 ° C. heating roll is used to adjust the apparent density to 0.35 g / cm ³ and the thickness to 1.1 mm. Pressed.

Next, dimethyl polyurethane elastomer having a nitrogen content of 4.5% based on isocyanate obtained by reacting polytetramethylene ether glycol having a molecular weight of 2050, 4,4'-diphenylmethane diisocyanate and ethylene glycol. The pressed entangled fibrous base material was impregnated with a formamide solution (13% concentration) and immersed in a 10% dimethylformamide aqueous solution to coagulate. Thereafter, the substrate was sufficiently washed in warm water at 40 ° C., and the ratio of fiber to polyurethane elastomer was 81: 1.
Thus, an elastic polymer-impregnated substrate of No. 9 was obtained.

Next, the substrate was repeatedly dipped and nipped in toluene at 80 ° C. to dissolve and remove the polyethylene, thereby making the composite fiber ultrafine. Thereafter, toluene contained in the substrate was azeotropically removed in hot water at 90 ° C.
It was dried in a hot air dryer at 0 ° C. The average fineness of the obtained ultrafine fibers was 0.08 denier.

Thereafter, the entangled fibrous base material subjected to the ultrafine treatment was sliced in a slicer in a plane direction and divided into two pieces.

Next, on the slice surface of the divided base material, 2
Using a 00 mesh gravure coater, a dimethylformamide solution containing 5% of the above-mentioned polyurethane elastomer was applied at a rate of 9 g / m ² , followed by drying and drying by heating.
After repeating this time, the slice surface was lightly buffed with a 400 mesh sandpaper.

The sheet thus obtained was a nubuck tone sheet having a very smooth and soft surface, a short nap fiber length, a sharp chalk mark property, and a uniform nap state.

Comparative Example 1 A treatment was performed under the same conditions as in Example 1 except that dimethylformamide was not applied to the slice surface of the divided base material. The obtained sheet had a long surface nap fiber length, lacked sharp chalk mark properties, did not provide a nubuck-like appearance, but rather exhibited a suede-like appearance.

[Comparative Example 2] In Example 1, dimethylformamide was applied after buffing the sliced surface of the divided base material, but the length of the nap fiber became long and the nap state became non-uniform. As a result, a good nubuck sheet was not obtained.

Comparative Example 3 The same procedure as in Example 1 was carried out except that the entangled fibrous base material subjected to the ultrafine treatment was not sliced in the plane direction, and dimethylformamide was applied to the base material surface as it was. Processing was performed under the conditions. The obtained sheet was inferior in the smoothness and uniformity of the napped surface.

[0051]

According to the production method of the present invention, the rubber-like appearance and texture are eliminated, and the surface is smooth, flexible and has a sharp chalk mark property without the need for a two-step ultrafine treatment. In addition, it is possible to produce a good nubuck-like artificial leather having a short bristle foot and a uniform napped state.

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ identification code FI // D06C 11/00 D06C 11/00 Z (58) Field surveyed (Int. Cl. ⁷ , DB name) D06N 3/00- 3/18 D01F 8/04 D04H 1/42 D06M 15/00 D06C 11/00

Claims (4)

(57) [Claims] 1. A web is formed from at least (a) an ultrafine composite fiber composed of two or more kinds of high molecular polymers, and (b) 500 to 3000 fibers / cm ^{2 in} the thickness direction of the web. (C) impregnating the entangled fibrous base material with an elastic polymer and allowing it to solidify; and (d) subsequently entangled with the entangled fibrous base material. Ultrafine composite fibers that make up the fibrous base material,
(E) Thereafter, the entangled fibrous base material is sliced in the plane direction and divided into a plurality of sheets. (F) A solvent of an elastic polymer is applied to the sliced surface of the divided entangled fibrous base material. After applying a liquid to dissolve or swell a part of the elastic polymer, the liquid is removed and solidified, and (g) buffing treatment is performed on the solvent-containing liquid treated surface of the entangled fibrous base material. A method for producing a nubuck-like artificial leather, characterized by performing the following. 2. The artificial nubuck leather according to claim 1, wherein at least one kind of polymer is dissolved and removed from a composite fiber comprising two or more kinds of polymer having different solvent solubility to obtain a fine fiber. Manufacturing method. 3. The method for producing a nubuck-like artificial leather according to claim 1, wherein the average fineness of the ultrafine fibers is 0.2 denier or less. 4. The artificial nubuck leather according to claim 1, wherein the amount of the liquid containing the solvent of the elastic polymer applied to the slice surface of the entangled fibrous base material is 5 to 55 g / m ^2. Manufacturing method.