JP3122574B2 - Method and apparatus for producing leather-like sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a simultaneous reproduction technique in the processing of a grain surface in the production of artificial leather, and more particularly to a leather-like sheet excellent in quality which does not generate pinholes or the like in the leather-like sheet. The present invention relates to a manufacturing method and an apparatus therefor.

[0002]

2. Description of the Related Art Conventionally, a leather-like sheet having a silver surface layer in which an elastic polymer coating layer (for example, polyurethane) is formed on one surface of a fiber assembly (substrate) containing an elastic polymer (for example, polyurethane). The method for producing is already known. Conventionally, this artificial leather or synthetic leather product is manufactured as follows.

[0003] That is, the production process of the leather is roughly divided into a base fabric process, a base material process, a grain surface process, and a finishing process. The base fabric process is firstly made of polyester staples and nylon staples of artificial short fibers. Is made into raw cotton, each staple is evenly mixed at a ratio of 1: 1 by a fiber blender process, and the mixed cotton is temporarily stored in a stocker process and automatically supplied to the next process. In the carding process, the fibers are uniformly opened and formed into a web, and the web is formed and laminated in a cross-wrapper process. The laminated webs are three-dimensionally entangled by a needle stick in a double needle locker (NLD) process, thereby increasing the density of the nonwoven fabric and stabilizing the dimensions.

[0004] Next, in the base material step, first, the shrinkage of the shrinking ester portion of the nonwoven fabric is developed in a hot water tank to increase the density and reduce the NLD needle mark. Then, in order to develop dimensional stability and softness, the substrate is immersed in a PVA impregnation tank, glued with PVA, and dried with a drier to obtain a substrate. The base material is subjected to hot pressing to regulate the thickness, smoothen the surface, and increase the density. Then, the base material is immersed in a polyurethane impregnation tank to naturally fill the polyurethane resin. Then, the polyurethane resin is coagulated by replacement with water and a solvent (DMF) in the regenerating coagulation tank, and at the same time, PVA is eluted, and a non-adhesion part is provided between the polyurethane fibers to impart softness. After the coagulation is completed, DMF and PVA are eluted in a washing tank. After the dissolution, a treatment for improving the flexibility of the base material and preventing permeation at the time of gluing the product is performed in a water-repellent flexible tank, and the base material is obtained by drying with a dryer.

[0005] Next, in the silver surface process, first, air bubbles in the coating solution which cause a defective defect (pinhole) are removed from the base material by a defoaming machine, and a predetermined amount of coating is applied by a coating machine. I do. Then, the coating liquid (polyurethane resin) is coagulated by replacement of water and DMF in the regenerating tank, and DMF is eluted in the washing tank, followed by drying and stretching in a drier to obtain an unfinished fabric. In the final finishing process, the unfinished fabric is embossed into an arbitrary pattern with an embossing machine, colored in a predetermined color with a toning machine, inspected and graded by a testing machine, and finished. .

However, if the polyurethane impregnation treatment and the silver surface treatment are separately performed as described above, the process becomes complicated since the polyurethane impregnation treatment requires a regeneration coagulation treatment, a water washing treatment, and a drying step. This requires a lot of processing equipment and space, and consumes a lot of energy such as water, steam and electricity for each processing.

[0007] Further, regarding the quality of the leather-like sheet after finishing the grain surface processing, which is an intermediate product, after drying the polyurethane impregnated substrate, the surface is coated with polyurethane to form a silver surface coating layer. The interlayer structure breaking force (hereinafter, referred to as “peeling strength”) near the joint boundary between the base material and the surface coating layer is weak. Therefore, after impregnating the substrate with polyurethane, without coagulation, washing and drying, the polyurethane-impregnated substrate is coated with silver in a wet state,
A so-called simultaneous regeneration technique with improved peel strength is disclosed in JP-A-62-110990 and JP-A-62-11099.
No. 1 discloses this.

For example, the former JP-A-62-110990
Japanese Patent Laid-Open Publication No. H11-15064 proposes a method of impregnating and applying a solution of a polymer mainly composed of an elastic polymer to a fiber sheet, coagulating the fiber sheet by a wet method or a dry method, and drying to obtain a leather-like sheet. In the latter JP-A-62-110991, a binder having an adhesive property or an affinity for an elastic polymer is applied to one surface of a substrate containing an elastic polymer in a fiber assembly, and if necessary, A method of producing a leather-like sheet having a strong peeling strength by applying a solution of an elastic polymer to form a silver surface layer after solidification has been proposed.

[0009]

However, if the substrate is impregnated with polyurethane and then subjected to a simultaneous regeneration treatment in which the surface of the impregnated substrate is coated with a silver surface layer without being subjected to a coagulation treatment, Since the surface is covered with the silver layer, bubbles contained in the impregnated base material are not easily removed. For this reason, as shown in FIG. 3, the air bubbles 3 that have not escaped from the surface of the grain surface layer adhere to the surface and cause air pockets, so-called pock marks 5 and small pinholes when air bubbles escape from the grain surface layer. 6
Or a so-called air mark 4 having a concave shape. This phenomenon is due to the fact that even if polyurethane which has been sufficiently defoamed at the time of impregnation and application is used, air is contained between the fibers, and when this air escapes from the coated silver surface layer, the leather-like intermediate product The sheet had the above-mentioned defects.

[0010] Therefore, if any one of the above defects occurs on the surface of the leather-like sheet, the sheet becomes a downgraded product. In particular, since the sheet is manufactured in a long shape while being wound on a roll, if such a defect occurs in some places, the entire product including a good part is downgraded, which has been a problem. Further, when a binder having adhesiveness or affinity with an elastic polymer is used as in the latter conventional technique, there is a disadvantage that the finished substrate lacks softness. The present invention has been made in view of such circumstances, and in the simultaneous regeneration technology in the grain surface processing of artificial leather production, the defect of the grain surface layer due to bubbles and the like is completely eliminated, and the base material is eliminated. It is an object of the present invention to provide a method and apparatus for producing a leather-like sheet of excellent quality that can enhance the peeling strength between the sheet and the grain surface layer.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to produce a leather-like sheet having a silver surface layer by forming an elastic polymer coating layer on one surface of a base material containing an elastic polymer in a fiber assembly. In doing so, the fibers constituting the fiber aggregate and the fiber aggregate are naturally saturated and impregnated with the elastic polymer, and after impregnating the impregnated elastic polymer into the fiber aggregate, a coating layer is formed on the surface. This is achieved by a method for producing a leather-like sheet, characterized in that a solution of an elastic polymer is applied and solidified to form a surface coating layer.

An apparatus for realizing this method is an apparatus for producing a leather-like sheet in which a fibrous aggregate containing a pore-forming agent or a foaming agent is impregnated with an elastic polymer, and a silver layer is formed on one surface thereof. The fiber assembly is run in a solution of the elastic polymer or in contact with the liquid surface, and in the running process, an impregnating tank for impregnating the elastic polymer by natural saturation is provided downstream of the impregnating tank. It has a squeezing device that presses the elastic polymer impregnated by applying tension to the fiber assembly, and a coating doctor that is directly connected to the squeezing device and adjusts the coating amount at the outlet by freely setting the gap with the coating roll. And a coating apparatus formed with a coating tank containing an elastic polymer forming a silver layer on the upper surface of the running base material. .

Further, the squeezing device comprises an impregnating doctor constituting an inlet side wall of a coating tank, and a concave elastic polymer collecting tank having receiving portions on the left and right around the impregnating doctor arranged vertically. The object is achieved by providing a tension to the base material by moving the base material between the two members and bringing the base material close to each other, thereby uniformly impregnating the elastic polymer impregnated in the base material.

Here, the base material referred to in the present invention is a woven or knitted fabric made of synthetic fiber or natural fiber, a fiber assembly itself such as a brushed product or a nonwoven fabric, and a binder processed into the fiber assembly. Things are used. Usually, cotton, rayon,
Nylon, polyester and the like are often used. As the binder, a polymer elastomer is optimal, and polyacrylate, polyurethane, polystyrene butadiene rubber, polyacrylonitrile butadiene rubber, or a copolymer thereof is used.

Next, an elastic polymer mainly composed of a polyurethane elastomer to be impregnated on the base material or coated thereon will be described. The polyurethane elastomer refers to a polymer composed of a polyol, an organic diisocyanate, and a chain extender and mainly polymerized by urethane bonds. A small amount, for example, 5 to 30%, of another polymer may be mixed mainly with the polymer. Other polymers can be considered variously depending on the purpose, but it is a necessary condition that the polymer is essentially dissolved in a solvent in which the polyurethane-based polymer is dissolved. Further, it is possible to mix inorganic and organic heavy dispersants and other additives.

The components constituting the polyurethane elastomer will be described in more detail. First, polyol is mainly a molecular weight having a hydroxyl group at both terminals of 500 to 3000.
It is a compound of about a polyether type and a polyester type. Examples of the polyether type include polypropylene glycol ether and polytetramethylene glycol ether, and a copolymer thereof may be used. Polyester types include low molecular weight glycols such as ethylene glycol, 1,4-butylene glycol,
There are polylactone types such as those obtained by polycondensation reaction of 6 hexane glycol and the like with dicarboxylic acids such as adipic acid, sebacic acid and isophthalic acid, and poly-ε-caprolactone. Also having an organic diisocyanate group, for example, 2,4 tolylene diisocyanate,
4,4 diphenyl methane diisocyanate, 1,6 hexane diisocyanate and the like can be mentioned. Further, the chain extender as the last component is a compound having two active hydrogens, and is mainly a low molecular compound. For example, there are glycols such as ethylene glycol and butylene glycol, diamines such as hydrazine, ethylenediamine, 1,2 propylenediamine, and m-tolylenediamine, and amino alcohols. Examples of the method for polymerizing the polyurethane elastomer include solution polymerization, bulk polymerization, and powder polymerization. For the purpose of the present invention, solution polymerization performed in a solvent described below is preferable. The reason for this is that it is a polymerization method in which the viscosity, concentration, etc. can be controlled with high precision in order to coat the above-mentioned belt in a solution form.

Among the polyurethane elastomers mentioned above, the most preferred standard ones are those comprising polybutylene adipate as a polyol, 4,4 diphenyl diisocyanate as an organic diisocyanate, and ethylene glycol as a chain extender. Another feature of the polyurethane elastomer is that the hardness of the polyurethane can be relatively freely changed by changing the molar ratio between the polyol and the organic diisocyanate.

Although there are various solvents for these polyurethane elastomers, a water-miscible solvent is required for the method for producing a microporous silver surface of the present invention. For example, N, N dimethylformamide, N, N dimethylacetamide, dimethylsulfoxide, tetramethylurea, N-methylpyrrolidone, and the like. Also, dioxane, methyl ethyl ketone, tetrahydrofuran and the like can be used as a partially diluted solvent. The above-mentioned polymer mainly composed of a polyurethane elastomer is used as the solvent solution. The polymer concentration is generally 15 to 40% by weight, preferably 1 to 40% by weight.
It is 5 to 30% by weight, more preferably 20 to 25% by weight. The viscosity varies depending on the density of the substrate to be applied, but is from 5,000 to 30,000 centipoise. The most preferred solvent used is N, N dimethylformamide in view of being industrially inexpensive and a good solvent for polyurethane elastomers.

[0019]

Next, the present invention will be described in detail with reference to examples. FIG. 1 shows an embodiment of an apparatus for simultaneously regenerating a base material used in the present invention. In the figure, reference numeral 1a denotes a substrate which is immersed in a PVA impregnating tank (not shown), glued with PVA and dried. Reference numeral 19 denotes an impregnation tank similar to the conventional example, in which an elastic polymer (hereinafter referred to as impregnation liquid 20) is stored. Reference numerals 15, 16, 17, and 18 denote guide rollers for the base material, and guide rollers 15 and 18 disposed above one end and the other end of the impregnation tank 19, and an impregnating liquid in the impregnation tank 19. 20, the guide rollers 16 disposed at regular intervals in the
17 is comprised. Reference numeral 12 denotes an elastic polymer coating layer (hereinafter referred to as coating liquid 21) on the surface of the substrate 1b impregnated with the impregnating liquid 20.
Is applied to form a silver surface layer.

The coating device 12 is provided above the running base material 1b, and stands up along the running direction of the base material 1b. A frame body for containing the impregnating liquid is constituted by side walls (not shown) erected in parallel with each other at a width interval of the base material, and the coating liquid is applied to the surface of the running base material 1b. .
The coating doctor 11 has a plate-like shape and is erected on the upper surface of a large-diameter coating roll 10 in parallel with the axial direction so that the gap can be freely adjusted.
By appropriately setting the gap with the lower end of the coating doctor 11, the thickness of the grain surface layer can be controlled.

The impregnating doctor 13 erected on the base material inlet side of the coating device 12 also serves as one side wall of the coating device, and the left and right of the base material 1b around the impregnating doctor 13.
V-shaped recovery groove 14 having a receiving portion is vertically arranged,
A squeezing device for squeezing a predetermined amount of air existing in the impregnated base material 1b together with the impregnating liquid between the two is constituted. That is, by moving the impregnated base material 1b between the impregnating doctor 13 and the collection groove 14, and bringing the upper and lower positional relations between the impregnated base material 1 and 13 close to each other, tension is given to the running base material 1b, 1
The impregnating liquid 20 impregnated in b and the air contained therein can be squeezed out by a predetermined amount.

In this configuration, the base material 1a impregnated with the pore-forming agent or the foaming agent (for example, polyvinyl alcohol) in the previous step is supported by the guide roller 18 and is placed in the lower impregnation tank 19. , And then rises up, passes through the lower surface of the coating device 12 via a guide roller 15 disposed above the impregnation tank 20, and passes through the outer periphery of the coating roll 10. The surface is slid and supplied to a regeneration coagulation tank, a washing tank, and a drier (not shown) to produce a leather-like sheet having a grained surface.

That is, in the impregnation tank 19, the substrate 1a
Is lowered by the roller 18 into the impregnation liquid in the impregnation tank 19, and when traveling between the rollers 16 and 17, the impregnation liquid 20 permeates into the base material due to natural saturation, and the impregnation process is continuously performed. Become so. Next, the impregnated substrate 1b
After being pulled up from the impregnation tank 19 via the roller 15, it passes between the impregnation doctor 13 and the recovery groove 14, and only the surface thereof comes into contact with the previously defoamed coating liquid surface. The coating liquid is supplied in the illustrated direction by the rotation of the coating roll 10 while being scraped to apply a fixed amount of the coating liquid.

In this running process, the impregnated base material 1b running while being pulled with a constant tension, as shown in FIG. 2, receives the receiving portions 14a, 1a of the collecting groove 14 provided across the base material 1b.
4b is pressed from above by the impregnation doctor, so that the substrate 1b is further tensioned. By this tension application, the impregnating liquid in the impregnated base material 1b penetrates further into the back and is uniformly distributed and impregnated, and the residual air contained in the base material is discharged. Since the squeezing device 30 composed of the impregnated doctor 13 and the collecting groove forms a part of the coating device, the base material 1 stretched by the squeezing device 30 is removed.
When b passes through the collecting groove 14 while being in contact with the coating liquid 21, it shrinks due to tension expansion and contraction. Therefore, when the base material 1 b contracts, the coating liquid 21 sufficiently penetrates into the base material 1 b. Is done. Thereby, the peeling strength between the substrate 1b and the coating liquid forming the silver surface layer is strengthened, and even if some air remains in the substrate, the floating to these silver surface layers is prevented. You. For this reason, the so-called pock mark 5, pinhole 6, and air mark 4 which were generated in the coating method without defoaming the impregnated base material after impregnation as in the prior art were completely eliminated. .

The impregnating liquid 20, which has been squeezed out by a predetermined amount by the impregnating doctor 13, is collected in the collecting groove 14 provided below and returned to the impregnating tank 19 by a known collecting device using a pump (not shown). Also, this impregnated doctor
As shown in FIG. 2, since the position can be moved up and down by an air cylinder or a motor, etc., the thickness, density, material, thickness, processing method, and type of coating liquid of the base material, By appropriately adjusting the set position according to the viscosity or the like, the tension of the traveling base material 1b can be arbitrarily changed. This makes it possible to appropriately adjust the impregnation amount of the impregnating liquid and the peel strength between the silver surface layer and the substrate.

As described above, in the sheet manufacturing apparatus, after impregnating the base material, the impregnated base material is tensioned by the drawing device, and then the coating liquid is applied to the surface. As a result, tension is applied to the impregnated substrate by the drawing device, so that the impregnating liquid is forcibly transferred to the substrate by the effect of injecting the impregnating liquid, and uniform impregnation is further achieved. Furthermore,
By the impregnating liquid being forcibly transferred into the base material, the bubbles contained in the base material are discharged, and the base material passes through the recovery groove, the tension is relaxed, and when the base material shrinks, The coating liquid penetrates partially into the base material due to its penetrating action or suction force,
The adhesive strength between the substrate and the silver layer can be made stronger. This eliminates the occurrence of defects caused by air bubbles that have conventionally occurred, and does not use a binder in the coating liquid. Therefore, the peeling force can be enhanced while maintaining the softness of the base material. .

In the above embodiment, the impregnated doctor 1 was used.
It has been described that the upper and lower positions of 3 are fixed at appropriate positions. However, in order to make this position variable and constantly apply a constant tension to the base material to keep the amount of permeation and the peeling strength constant, the collecting groove of the drawing device is used. A load cell that detects the tension of the substrate is fixed below the
The detection signal may be compared with a target tension value set in advance for the base material, and based on this difference signal, the elevation of the impregnated doctor may be controlled so that the difference becomes zero.

In the embodiment, the V-shape is used for the collecting groove. However, it is sufficient that the running base material is supported at both ends around the impregnating doctor and the collected impregnating liquid can be collected. , U-shaped or corrugated plate. Further, in order to enhance the defoaming effect of the impregnated substrate, the inside of the recovery groove may be evacuated to more actively promote the impregnation of the impregnating liquid into the substrate.
Thereby, the quality can be further improved.

[0029]

As described above in detail, in the method of the present invention, in the simultaneous regeneration treatment step of impregnating and applying the elastic polymer to the fiber assembly, a drawing step for the base material is provided in the middle. By the defoaming action on the substrate, no defects were generated in the silver surface layer due to bubbles. In addition, the coating process imparts stretching and shrinking forces to the substrate, so that not only is the coating liquid coated on the surface of the substrate during shrinkage, but it also penetrates into the fiber structure of the substrate. And the peel strength of the silver surface layer can be further strengthened.

Further, since the peel strength is not improved by using a binder which is an adhesive as in the prior art, it is possible to produce a leather-like sheet of excellent quality without impairing the softness of the substrate. Further, according to the apparatus of the present invention, since the squeezing device is provided in a part of the coating apparatus, the apparatus can be made compact, and can be easily introduced into existing equipment without extensive modification.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention.

FIG. 2 is an enlarged view of the diaphragm device of FIG.

FIG. 3 is a cross-sectional view of a conventional leather-like sheet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Silver surface layer 3 Air bubble 10 Coating roll 11 Coating doctor 12 Coating device 13 Impregnation doctor 14 Recovery groove 19 Impregnation tank 20 Impregnation liquid 21 Coating liquid 30 Drawing device

Claims (3)

(57) [Claims] When a leather-like sheet having a silver surface layer is produced by forming an elastic polymer coating layer on one surface of a substrate comprising an elastic polymer in a fiber aggregate, the fiber aggregate is constituted. The fibers and the fiber assembly are naturally saturated and impregnated with the elastic polymer, and the impregnated elastic polymer is pressed into the fiber assembly, and then a solution of the elastic polymer forming a coating layer is applied to the surface. A method for producing a leather-like sheet, comprising: solidifying to form a surface coating layer. 2. An apparatus for producing a leather-like sheet, comprising impregnating a fibrous aggregate containing a pore-forming agent or a foaming agent with an elastic polymer and forming a grain surface layer on one surface thereof, wherein the fibrous aggregate is formed of an elastic polymer. The polymer is run in a solution or in contact with the liquid surface, and in the running process, an impregnating tank for impregnating the elastic polymer by natural saturation, and a tension is applied to the fiber assembly provided downstream of the impregnating tank. A squeezing device for press-fitting the elastic polymer impregnated therein, and a coating doctor that is directly connected to the squeezing device and adjusts a coating amount by freely setting a gap between the coating roll and an outlet,
An apparatus for forming a coating tank containing an elastic polymer forming a silver layer on the upper surface of a running base material. 3. A squeezing device comprising an impregnating doctor constituting an inlet side wall of a coating tank, and a concave elastic polymer collecting tank having receiving portions on the left and right around the impregnating doctor arranged vertically. 3. The production of a leather-like sheet according to claim 2, wherein the base material is run between the two members, and the base material is moved close to the base member to apply tension to the base material so as to uniformly impregnate the elastic polymer impregnated in the base material. apparatus.