JP2002249986A - Method for producing artificial leather - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an artificial leather which is efficiently subjected to compacting having excellent uniformity in the thickness direction of fiber entangled body sheet and has excellent tensile strength, tear strength, abrasion resistance and smoothness and denseness of the surface of product. SOLUTION: This method for producing an artificial leather comprises forming a fiber entangled body sheet in which an extra fine fiber generation type conjugate fiber composed of at least two components is entangled three- dimensionally and carrying out a process (1) for impregnating the fiber entangled body sheet with a heating medium, passing the fiber entangled body sheet through an atmosphere at >=80 deg.C and <=220 deg.C, compressing the fiber entangled body sheet in the thickness direction by press rolls having >=10 deg.C and <=80 deg.C temperature of roll surfaces while cooling the surfaces of the sheet and adjusting the impregnation ratio of the heating medium to >=30 wt.%; and <=200 wt.% and a process (2) for compressing the fiber entangled body sheet in the thickness direction by press rolls having >=100 deg.C and <=200 deg.C temperature of roll surfaces while boiling the heating medium and then removing the heating medium by drying in this order.

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 an artificial leather having excellent strength, abrasion resistance, smoothness and denseness of a product surface.

[0002]

2. Description of the Related Art In artificial leather comprising microfibers and elastic polymer, means for improving the tensile strength and tearing strength include increasing the needle density of a needle punch to increase the number of fiber entangled points, By using a polymer and increasing the shrinkage of the fiber entangled sheet,
Method to increase fiber density, compress the sheet in the thickness direction,
A method of increasing the fiber density and a method of increasing the weight of the elastic polymer have been used.

However, the method of increasing the needle density of the needle punch has a problem that if the needle density is too high, the fibers are cut and the strength is reduced. The method using a high shrinkage polymer has a problem that it is difficult to produce a wide product due to a large width shrinkage, and the method of increasing the amount of the elastic polymer has a problem that the feeling of the product becomes hard. have.

As a method of compressing a sheet in the thickness direction, there is a method of simply compressing the sheet with a press roll set at an arbitrary temperature, but a sufficient compression effect is obtained at or below the glass transition temperature of the polymer constituting the sheet. Is not obtained, when compressed at a temperature higher than the glass transition temperature, the sheet surface is heated and compressed preferentially, for example, a fiber entangled sheet containing a polymer having high rigidity and a low melting point such as polystyrene. If the density is to be sufficiently increased, the sheet surface is likely to be made into a plastic sheet, so that there is a problem that it is difficult to impregnate the elastic polymer in a later step.

A method in which the sheet is heat-treated and softened before the sheet is compressed by the press roll is more effective than a method in which the sheet is simply pressed. However, when the roll temperature is high, the sheet is compressed by the above-described high-temperature roll. The same problem as in the above case, that is, when attempting to sufficiently densify a fiber entangled sheet containing a polymer having a low melting point, the sheet surface is easily made into a plastic sheet, so that it becomes difficult to impregnate the polymer elastic body in a later step. Although the compression effect is high when the roll temperature is low, there is a problem that the thickness recovers when a shape fixing agent or a polymer elastic material is applied in a later step.

As a method of compressing a sheet in the thickness direction to obtain smoothness and denseness of a product surface, Japanese Patent Publication No.
No. 12351 discloses a method of pressing with a combination of a heating roll and a cooling roll. This method is effective in terms of smoothness and denseness, but has the disadvantage that the compression effect is insufficient, and when the sheet is cut in half in the thickness direction and divided into several sheets, quality unevenness occurs at the top and bottom. Had.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art at once by a compression technique capable of efficiently performing densification with excellent uniformity in the thickness direction of the fiber entangled sheet. Strong, abrasion resistance and surface smoothness,
An object of the present invention is to provide a method for producing artificial leather having excellent denseness.

[0008]

The present invention has the following arrangement to achieve the above-mentioned object. That is, a fiber entangled sheet formed by three-dimensionally entangled ultrafine fiber-generating conjugate fibers composed of at least two components is formed, and the following steps (1) and (2) are performed. Impregnated with a heating medium and then 80
After passing through an atmosphere temperature of not less than 220 ° C. and a press roll having a roll surface temperature of not less than 10 ° C. and not more than 80 ° C., the sheet surface is compressed in the thickness direction while cooling, and the impregnation rate of the heating medium is 30% by weight. Adjusting to at least 200% by weight. (2) A step of compressing the sheet in the thickness direction while boiling the heat medium with a press roll having a roll surface temperature of 100 ° C. or more and 200 ° C. or less, and then drying and removing the heat medium. In this order.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The ultrafine fiber-generating conjugate fiber used in the present invention is formed by conjugate spinning or mixed spinning using at least two component polymers having different properties such as solvent solubility, decomposable agent decomposability, and heat shrinkability. This is a conjugated fiber which is capable of dissolving and removing at least one component or exfoliating and splitting by physical or chemical action to produce an ultrafine fiber. The cross-sectional forms of the conjugate fiber and the ultrafine fiber are not particularly limited.

Examples of the polymer forming such ultrafine fibers include polyamides such as nylon 6, nylon 66, nylon 12, and copolymerized nylon, and polyesters such as polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate and / or copolymers thereof. Can be used.

Examples of the polymer which is removed by dissolution or peeled or divided by physical or chemical action include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate and / or a copolymer thereof, nylon 6, nylon 66, and the like. Polyamides such as nylon 12 and copolymerized nylon, and polyolefins such as polyethylene and polystyrene can be used.

In obtaining the fiber entangled sheet used in the present invention, for example, a method is used in which short fibers of ultrafine fiber-generating conjugate fibers are formed into a web and formed into a sheet by an entanglement means such as a needle punch or a water jet punch. It can be performed, but is not particularly limited.

In the present invention, the fiber entangled sheet is impregnated with a heat medium, passed through an ambient temperature of 80 ° C. or more and 220 ° C. or less, and then pressed with a press roll having a roll surface temperature of 10 ° C. or more and 80 ° C. or less. It is compressed in the thickness direction while cooling, and the impregnation rate of the heat medium is adjusted to 30% by weight or more and 200% by weight or less.

The heat medium used in the present invention may be water or an aqueous solution of dimethylformamide, dimethylsulfoxide, tetrahydrofuran, or the like, or a form-fixing agent such as polyvinyl alcohol, starch, or polyhydric acid. An aqueous solution containing a sizing agent such as acrylamide can be preferably used. In addition, if a metal salt such as sodium chloride or potassium chloride is added to water or an aqueous solution as a heat medium, the softening of the sheet during heating is promoted by increasing the boiling point of the solution by using the increase in the boiling point, and the sheet is heated. It is preferable because it can be easily compressed.

In the present invention, hot water, hot air, high-pressure steam, or the like can be preferably used as a method for adjusting the ambient temperature to 80 ° C. or higher and 220 ° C. or lower. If the ambient temperature is lower than 80 ° C., the sheet is insufficiently softened, and a sufficient compression effect cannot be obtained, which is not preferable. If the ambient temperature exceeds 220 ° C., the rate of evaporation of the heating medium becomes high, and it becomes difficult to control the impregnation rate.

The roll surface temperature of the press roll for compressing the heated sheet is from 10 ° C. to 80 ° C. Here, by compressing the heated surface of the sheet while cooling it, the inside of the sheet is preferentially compressed. If the roll temperature is lower than 10 ° C., the sheet tends to be hard and the roll load tends to increase, which is not preferable. On the other hand, if the roll surface temperature exceeds 80 ° C., the temperature difference between the sheet and the roll becomes small, and the object of preferentially compressing the inside of the sheet cannot be achieved.

The impregnation rate of the heat medium is as follows.
After passing through an atmosphere temperature of 0 ° C. or less, the pressure is adjusted by compression with a press roll having a roll surface temperature of 10 ° C. or more and 80 ° C. or less. If the impregnation rate is less than 30% by weight, the sheet becomes completely dry immediately during the compression of the sheet, so that the compression effect is lowered and the sheet cannot be uniformly compressed, which is not preferable. If the impregnation rate exceeds 200% by weight, heating of the sheet during compression becomes insufficient, and the compression effect is undesirably reduced.

Next, the fiber entangled sheet whose impregnation rate of the heat medium is adjusted is passed through a press roll having a roll surface temperature of 100 ° C. or more and 200 ° C. or less, and is compressed in the thickness direction while boiling the heat medium. If the roll surface temperature is lower than 100 ° C., the heating medium does not boil, so that it is difficult to obtain a sufficient compression effect. If the roll surface temperature exceeds 200 ° C., the sheet surface is likely to be made into a plastic sheet due to fusion of the fibers on the sheet surface, and it is difficult to impregnate the polymer elastic body in a later step, which is not preferable.

In the present invention, it is preferable to impart a polymer elastic body to the fiber entangled body containing the ultrafine fibers, the ultrafine fiber bundle, or the ultrafine fiber-generating conjugate fiber. The polymer elastic body may be provided before the ultrafine fiber generating conjugate fiber is subjected to the ultrafine treatment, or may be provided after the ultrafine treatment. As the polymer elastic body, for example, a polyurethane elastomer, a polyurea elastomer, a polyurethane / polyurea elastomer, a polyacrylate resin, an acrylonitrile / butadiene elastomer, a styrene / butadiene elastomer, and the like can be used. Among them, a polyurethane elastomer, a polyurea elastomer, Polyurethane elastomers such as polyurethane / polyurea elastomers are preferred. As these polyurethane elastomers, for example, it is preferable to use at least one selected from polymer diols having an average molecular weight of 500 to 3500, such as polyester diol, polyether diol, polyester polyether diol, polylactone diol, and polycarbonate diol. . From the viewpoint of the durability of the product, polyurethane using a polymer diol containing 30% by weight or more and 90% by weight or less of polycarbonate diol is more preferable. If the content of the polycarbonate diol is less than 30% by weight, the durability decreases, and if it exceeds 90% by weight, the feeling becomes hard, which is not preferable.

The polycarbonate diol referred to in the present invention is preferably a polycarbonate diol in which a diol skeleton is connected via a carbonate bond to form a polymer chain and has a hydroxyl group at both ends thereof. Is determined by the glycol used, but the type is not particularly limited. For example, 1,6-hexanediol, 1,5-pentanediol, neopentyl glycol, 3-methyl-1,5-pentanediol Can be preferably used. Further, it is preferable to use a copolymerized polycarbonate diol using at least two or more glycols selected from these glycol groups as raw materials, since an artificial leather having particularly excellent flexibility and appearance can be obtained. When an artificial leather having particularly excellent flexibility is obtained, it is preferable to introduce a bond other than a carbonate bond, for example, an ester bond, an ether bond, or the like into the polymer diol as long as durability is not impaired.

As a form for introducing such a chemical bond,
Polycarbonate diols and other polymer diols may be independently polymerized and then mixed and used for polyurethane polymerization.

In the present invention, the amount of the elastic polymer is
From the viewpoint of the flexibility of the product, the surface touch, the uniformity of dyeing, and the like, the solid content is preferably in the range of 10 to 70% by weight based on the weight ratio of the ultrafine fibers. If the coating weight is less than 10% by weight, the abrasion is likely to decrease, which is not preferable. If the amount exceeds 70% by weight, the hand tends to be hard, which is not preferable.

If necessary, additives such as a colorant, an antioxidant, an antistatic agent, a dispersant, a softener, and a coagulation regulator may be added to the elastic polymer.

Next, it is preferable that at least one surface of the sheet is raised to form a fiber raised surface. Various methods such as buffing with sandpaper or the like can be used as a method for forming the fiber raised surface.

The above-mentioned brushed sheet is preferably dyed with a liquid jet dyeing machine such as Circular, Uniace, etc. in order to further add value to the product, and then subjected to finishing.

[0027]

Next, the present invention will be described in more detail by way of examples. Example 1 Polyethylene terephthalate as an island component, polystyrene as a sea component, component ratio 55/45, number of islands 36,
Using a raw fiber of sea-island type ultrafine fiber generating composite fiber having a composite fineness of 3.0 dtex, an island fineness of 0.05 dtex and a fiber length of 51 mm, carded and wrapped into a fiber laminated web, needle punching is performed, and a basis weight of 550
g / m ^2, to prepare a fiber-entangled sheet having a thickness of 2.5 mm. After impregnating the thus obtained sheet with hot water, the sheet is squeezed by a press roll and then passed through hot air at 180 ° C., compressed while cooling the sheet surface with a press roll at a roll temperature of 40 ° C., and simultaneously containing water. The rate was adjusted to 60% by weight. Next, the water content-adjusted sheet was compressed by a press roll having a roll surface temperature of 120 ° C. while boiling water remaining on the sheet, and dried. After applying polyvinyl alcohol to this sheet, the sea component is dissolved and removed with trichlene to express ultrafine fibers, and polyurethane using a polymer diol containing 70% by weight of polycarbonate diol is added to the sheet by about 25% by weight based on the sheet weight.
After slicing, the applied product was raised with a buffing machine.
Thereafter, using a circular dyeing machine, the product was dyed brownish with a disperse dye to obtain a suede-like artificial leather having a thickness of 0.40 mm.

The evaluation results are shown in Table 1. Example 2 The same method as in Example 1 was used except that a copolymerized polyethylene terephthalate containing 8 mol% of 5-sodium sulfoisophthalic acid and 1 mol% of isophthalic acid was used as a sea component, and an aqueous sodium hydroxide solution was used as a desealing solvent. Thus, a suede-like artificial leather having a thickness of 0.40 mm was obtained.

The evaluation results are as shown in Table 1. Comparative Example 1 550 g / m ² in area weight and 2.5 mm in thickness in Example 1
Was impregnated with hot water, compressed by a press roll, and dried. This sheet was subjected to the application of polyvinyl alcohol, ultrafine treatment, application of polyurethane, slicing, raising, and dyeing in the same manner as in Example 1 to obtain a suede-like artificial leather having a thickness of 0.42 mm.

The evaluation results are as shown in Table 1. Comparative Example 2 550 g / m ² in area weight and 2.5 mm in thickness in Example 1
Was impregnated with hot water, compressed by a press roll, and dried. This sheet was heated in hot air at 180 ° C. and then compressed by a press roll having a roll surface temperature of 120 ° C. This sheet was subjected to the application of polyvinyl alcohol, ultrafine treatment, application of polyurethane, slicing, raising, and dyeing in the same manner as in Example 1 to obtain a suede-like artificial leather having a thickness of 0.40 mm.

The evaluation results are as shown in Table 1.

[0032]

[Table 1]

[0033]

According to the present invention, since the fiber entangled sheet can be uniformly densified in the sheet thickness direction, it can be used not only for a thick material, but also for an ultra-thin material which has conventionally been difficult to balance with physical properties. It is possible to provide a method for producing artificial leather having excellent tensile strength, tear strength, abrasion resistance and surface compactness.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) D06M 15/572 D06M 15/572 F-term (Reference) 3B154 AA07 AA09 AA17 AB22 BA19 BB03 BB12 BB15 BB32 BC22 BF01 BF10 BF13 DA06 DA07 DA10 DA19 4F055 AA02 BA11 DA07 EA04 EA05 EA07 EA12 EA24 FA07 FA20 GA02 HA04 4L033 AA07 AB07 AC11 CA06 CA23 CA29 CA52 4L047 AA27 AB02 AB08 BA09 BA23 BA24 BB09 CB01 CB10 CC16 DA00 EA10

Claims (3)

[Claims] 1. A fiber entangled sheet formed by three-dimensionally entanglement of ultrafine fiber-generating conjugate fibers comprising at least two components, and the following steps (1) and (2): The coalesced sheet is impregnated with a heat medium,
After passing through an atmosphere temperature of not less than 220 ° C. and a press roll having a roll surface temperature of not less than 10 ° C. and not more than 80 ° C., the sheet surface is compressed in the thickness direction while cooling, and the impregnation rate of the heating medium is 30% by weight. Adjusting to at least 200% by weight. (2) A step of compressing the sheet in the thickness direction while boiling the heat medium with a press roll having a roll surface temperature of 100 ° C. or more and 200 ° C. or less, and then drying and removing the heat medium. Are performed in this order. 2. The heating medium is one which does not substantially dissolve the shape fixing agent and / or the fiber entangled body and the polymer elastic body, and contains a substance soluble in water, so that the boiling point of water is reduced. 2. The method for producing artificial leather according to claim 1, wherein the temperature is higher than the boiling point. 3. The artificial material according to claim 1, wherein the fiber entangled body is provided with a polyurethane using a polymer diol containing 30% by weight or more and 90% by weight or less of polycarbonate diol as a polymer elastic body. Leather manufacturing method.