JPH07145569A - Method for producing smooth leather-like sheet - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a leather-like sheet material that is flexible, has fine wrinkles, has a smooth surface, and is lightweight. [Structure] A web (A) made of a shrinkable polyester fiber having a shrinkage ratio of at least 20% in hot water at 70 ° C. and a crystallinity of 20% or less and a web made of a fiber which does not substantially heat shrink ( (B) and (B) are laminated so that the web (A) sandwiches the web (B), and after needle punch entanglement treatment, shrinkage of 20% or more and 50% or less in area shrinkage is applied, and at the same time as shrinkage or After the shrinkage, the shrinkable polyester fiber is crystallized so that the crystallinity of the shrinkable polyester fiber is at least 30% to obtain a fiber sheet, and then the fiber sheet is impregnated with a solution or dispersion of a polymer mainly composed of an elastic polymer. After that, it solidifies by a wet method or a dry method,
A method for producing a soft and smooth leather-like sheet, which comprises finishing the sheet obtained by drying.

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 leather-like sheet material which is flexible, smooth and lightweight.

[0002]

2. Description of the Related Art Many proposals have been made for a method for producing a fiber sheet which is conventionally used for producing a leather-like sheet material. For example, Japanese Patent Publication No. 41-21425 proposes to shrink a fiber mat from 30 to 50%, impregnate it with a synthetic polymer binder, and solidify it to produce a suede-like material. Japanese Patent Publication No. 56-18698 discloses that a polyester fiber having a different heat shrinkage is mixed at a specific ratio to make a web, and a heat shrinking treatment is performed to obtain a cantilever bending resistance of 9%.
A method of making a flexible nonwoven fabric of 0 mm or less has been proposed. Japanese Examined Patent Publication No. 59-53388 discloses a web made of a highly shrinkable polyester fiber having a potential spontaneous stretchability.
There has been proposed a method of producing a flexible fiber sheet having drape by performing entanglement treatment, shrinkage treatment, and then spontaneous stretching treatment. Japanese Examined Patent Publication (Kokoku) No. 5-45714 discloses that a shrinkable polyester fiber and a non-shrinkable polyester fiber are mixed at a specific ratio to form an entangled nonwoven fabric, which is subjected to shrinkage treatment and then subjected to crystallization treatment to impart an elastic polymer to leather. There has been proposed a method for producing a sheet-like material having the same texture. As a method for producing a leather-like sheet material by laminating webs, a thin denier fiber is used in the surface layer described in Japanese Patent Publication No. 42-18599, and fibers having a larger denier are sequentially laminated toward the lower layer. A method of forming a structure similar to natural leather by shrinking and shrinking, Japanese Patent Publication Sho 62
No. 29548 discloses a method of laminating multi-component fibers having different solvent-soluble components to give a density gradient, and the like.

[0003]

It is difficult to reduce the weight of a fiber sheet produced by a conventional manufacturing method, because the degree of the entanglement of the fibers is increased by the shrinking treatment and the appearance density becomes high. . Furthermore, the fiber sheet that has just shrunk does not have sufficient fiber fixation, so it stretches even with a relatively small tension and is morphologically unstable, and a fiber material made by containing an elastic polymer in the shrunk fiber sheet. Even with a sheet, a morphological change is likely to occur during processing of a secondary product or when worn, and it has been difficult to combine the good texture of a fibrous sheet to the final product. In addition, a web in which shrinkable fibers and non-shrinkable fibers are mixed has a large amount of non-shrinkable fibers on the surface of the web, which makes it difficult to set heat, and strong heat pressing conditions are required to obtain a smooth surface. Therefore, the apparent density of the fiber sheet is inevitably high, and it is difficult to combine smoothness and light weight. On the other hand, in the method of sequentially laminating fibers having different denier, a thick denier fiber is used as the lower layer, so that a hard and stiff sheet material is obtained. When a multi-component fiber is used, a soft and sheet-like material similar to natural leather is obtained.
There are problems that the apparent density becomes large during the extraction process, the manufacturing process becomes complicated, and the cost becomes high.

An object of the present invention is to provide a leather-like sheet material which is soft, has fine wrinkles, has a smooth surface, and is lightweight.

[0005]

According to the present invention, when a lightweight leather-like sheet having a smooth surface is manufactured at 70 ° C.
A web (A) made of a shrinkable polyester fiber having a shrinkage ratio of at least 20% in hot water and a crystallinity of 20% or less, and a web (B) made of a fiber which does not substantially heat shrink. (A) is laminated so as to sandwich the web (B), subjected to needle punch entanglement treatment, and then given a shrinkage of 20% or more and 50% or less in area shrinkage, and at the same time as or after the shrinkage, a shrinkable polyester A fiber sheet is obtained by performing a crystallization treatment so that the crystallinity of the fiber is at least 30%, and then the fiber sheet is impregnated with a solution or dispersion of a polymer mainly containing an elastic polymer, followed by a wet method. Alternatively, it is a method for producing a soft and smooth leather-like sheet material, which comprises solidifying by a dry method and drying to obtain a sheet material.

The present invention is also a method for producing a leather-like sheet material, characterized in that the fiber web (B) is a web made of hollow fibers that do not substantially shrink.

Further, the present invention is a method for producing a leather-like sheet, characterized in that the crystallization treatment is carried out by heat treatment and / or solvent treatment.

The low crystallinity and high shrinkability polyester fiber used in the present invention is a polyester fiber having a crystallinity of 20% or less and a shrinkage rate of at least 20% under the following heat shrinkage conditions. Such fibers have 8 units of low polyethylene terephthalate or ethylene terephthalate units.
Melt-spun copolymerized polyethylene terephthalate containing 0 mol% or more, and wound at a winding speed of 4100 m / min or less, and the fiber structure is kept to have low crystallinity and low orientation.
Alternatively, a polyester filament obtained by ordinary melt spinning is stretched at a low temperature at which the crystallinity does not become high, and the shrinkage is kept at a low crystallinity of at least 20% and a crystallinity of 20% or less. It can be obtained by the method.

On the other hand, as a fiber which does not substantially shrink,
The heat shrinkage obtained by ordinary stretching, heat treatment, etc. is 10
% Or less, for example, polyester-based fibers such as polyethylene terephthalate and isophthalic acid-modified polyethylene terephthalate, linear polyamide fibers such as 6,6-nylon and 6-nylon, and fibers such as polypropylene are not particularly limited. . Hollow fibers such as polyethylene terephthalate hollow fibers and polypropylene hollow fibers are particularly preferable from the viewpoint of reducing the weight of the web.

In order to produce an entangled nonwoven fabric, an oil agent necessary for producing an entangled nonwoven fabric is added to shrinkable fibers and non-shrinkable fibers, and crimping treatment is performed to obtain a nonwoven fabric having a fiber length of preferably 100 mm or less. Short fibers cut into fiber lengths are made into webs by a cross-wrapper, random webr, papermaking method, etc., and the webs are superposed in the order of shrink fiber web (A) -non-shrink fiber web (B) -shrink fiber web (A). Together,
Integrate with a needle punch.

As the shrinkage treatment of the entangled nonwoven fabric, a method of immersing the entangled nonwoven fabric in hot water, a method of heat treatment in a steam atmosphere or a dry heat atmosphere, and the like can be applied. The area shrinkage ratio due to the shrinkage treatment varies depending on the shrinkage ratio of the shrinkable polyester fiber, the ratio of the shrinkable polyester fiber web, etc. The ratio varies depending on the product to be directed, but the shrinkable fiber web (A) and the non-shrinkable fiber web (B ) Ratio is 20/80
It is preferably in the range of 60 to 40. If the shrinkable fiber ratio is less than 20%, it is difficult to increase the area shrinkage of the web to 20% or more, and the surface smoothness and creases become poor. On the other hand, when the shrinkable fiber ratio exceeds 60% and becomes large, the apparent density of the entangled nonwoven fabric becomes high, and a lightweight leather-like sheet material cannot be obtained. Further, when the weights of the shrinkable fiber webs of the upper layer (front surface layer) and the lower layer (rear surface layer) are different, the nonwoven fabric is likely to curl during the shrinking treatment. Therefore, the weight ratio of the webs of the upper layer and the lower layer is preferably close to 1. . The weight of the entangled nonwoven fabric varies depending on the intended use, but is generally in the range of 100 to 1500 g / m ² .

If the shrinkage treatment of the nonwoven fabric increases the crystallinity of the shrinkable polyester fiber, the subsequent crystallization treatment is not necessary. However, the hot water treatment generally does not result in a polyester fiber having a sufficiently high crystallinity, so that the crystallinity is further increased. It is necessary to carry out the processing. The crystallization treatment is, for example, a method of heat-treating the entangled nonwoven fabric after hot water shrinkage at 150 ° C. or higher and at a temperature 20 ° C. or lower lower than the melting temperature of the fiber, acetone, ethane tetrachloride, benzene, toluene, N, N-dimethyl. The crystallinity of the shrinkable polyester fiber is adjusted to 30% or more by a method of treating with an organic solvent such as formamide.

The laminated non-woven fabric is, if necessary, subjected to a surface smoothing treatment prior to impregnation with a solution of a polymer mainly composed of an elastic polymer. As a method of the surface smoothing treatment, pressing with a hot roll is used. Any method such as a method, a method of smoothing along a smooth heating drum, a method of sandwiching an entangled nonwoven fabric between a smooth heating belt and a net, and smoothing may be used. As in the present invention, a web (A) made of a shrinkable polyester fiber having a crystallinity of 20% or less and a web (B) made of a fiber which does not substantially heat shrink are sandwiched between the web (A) and the web (B). When the entangled nonwoven fabric subjected to the needle punch entanglement treatment in this manner is used, the surface can be smoothed with a low pressing pressure, and a smooth fiber sheet having a low apparent density can be obtained.

The elastic polymer used for impregnating and surface-coating the fiber sheet of the present invention includes, for example,
At least one polymer diol selected from the group consisting of polyether diols, polyester ether diols, polycaprolactone diols, polycarbonate diols and the like having an average molecular weight of 500 to 3000; and organic polyisocyanates such as aromatic diisocyanates,
Polyurethane elastomer obtained by reacting at least one kind of organic iocyanate selected from the group of alicyclic diisocyanate, aliphatic diisocyanate, etc. with a low molecular compound having two or more active hydrogen atoms as a chain extender or Polyurethane urea elastomer. The composition of these polyurethanes can be appropriately selected from those satisfying various physical properties such as texture, deterioration resistance and yellowing resistance according to the application of the leather-like sheet material. Other elastic polymers that can be used in the fiber sheet include polyacrylic acid ester and synthetic rubber. Also,
The elastic polymer is used by dispersing it in a solution or a dispersant dissolved in a solvent, and may be used by dissolving or dispersing another polymer as necessary. In addition, it is also preferable to use as a composition liquid to which a filler, a colorant, a plasticizer, a flame retardant, a coagulation regulator and the like are added. Furthermore, it is also preferable to add a releasing material in order to prevent adhesion with the fibers.

Next, the fiber sheet is impregnated with a solution or dispersion of a polymer mainly composed of an elastic polymer, and if necessary, a solution or dispersion liquid of a polymer mainly composed of an elastic polymer is applied to the surface of the fiber sheet. The polymer is solidified by a method such as dipping in a non-solvent-based coagulation liquid for coagulation and coagulation by a wet method, or coagulation by a dry method in which treatment is carried out in a steam atmosphere or a dry heat atmosphere, and a sheet-like material. To do. Further, the solidified polymer does not adhere to the fibers of the fiber sheet, and it is preferable to form voids between the polymer and the fibers in terms of the final product texture, appearance and secondary processability. Therefore, prior to impregnating the fiber sheet with the polymer, a release agent such as a water-soluble resin such as polyvinyl alcohol is previously added to the fiber at any stage, or the polymer impregnating the fiber sheet is impregnated with the polymer. It is preferable to perform a treatment such as adding a releasing agent to the solution or dispersion.

If necessary, the obtained sheet-form material may be surface-smoothed by a known method, a silver surface layer may be applied, a surface coloring treatment,
Alternatively, a finishing treatment such as dyeing treatment, surface patterning and softening treatment is applied to obtain a leather-like sheet.

The crystallinity of the polyester fiber in the present invention is a value measured by a density method, and is a completely non-crystalline density of 1.335 g / cm ³ and a completely crystalline density of 1.
It is a value determined as 455 g / cm ³ .

[0018]

EXAMPLES Next, embodiments of the present invention will be described with reference to Examples. The parts and% in the examples relate to the weight unless otherwise specified. Further, the evaluation method of the product in the present invention is as follows. (1) Folded wrinkles: Sensory evaluation was performed on three levels. ○ ・ ・ ・ Fine wrinkles like natural leather △ ・ ・ ・ Slightly rough wrinkles × ・ ・ ・ Paper-like rough wrinkles

Example 1 Polyethylene terephthalate was melt-spun at a spinning speed of 3500 m / min, and the obtained filament was mechanically crimped by applying an oil agent while being undrawn, and dried by a low-temperature air dryer to obtain a fiber length. It was cut to 51 mm. This fiber was a shrinkable polyester fiber having a single fiber fineness of 2.5 denier, a shrinkage rate in hot water of 70 ° C. of 52%, and a crystallinity of 7.5%. After defibrating this, through a process of card, cross lap, pre-needle (40 punch / cm ² ), a basis weight of 60 g / m
To give ^2-shrinkable polyester fiber webs with (A). Next, a hollow polyethylene terephthalate fiber is spun by a known method, stretched, treated with an oil agent, crimped, and cut to obtain a single fiber fineness of 6 denier, a hollow ratio of 35%, and a shrinkage ratio in hot water of 70 ° C. of 1%. A hollow fiber having substantially no shrinkage was obtained. After defibrating this, card, cross wrap, pre-needle (4
Throughout each stroke of 0 punch / cm ² ), the basis weight is 120 g / m ²
A hollow polyethylene terephthalate fiber web (B) having substantially no shrinkage was obtained. These fibrous webs are superposed in the order of web (A) / web (B) / web (A), and are integrated by squeezing a needle punch of 400 punches / cm ² , and a laminated entangled nonwoven fabric having a basis weight of 210 g / m ^2. And

This entangled nonwoven fabric was dipped in hot water at 70 ° C. for 1 minute and squeezed with a mangle. This non-woven fabric is subjected to this dipping treatment, 18% in the lengthwise direction and 22% in the widthwise direction compared to before heat treatment.
%, 36% in area. Then, the water-containing nonwoven fabric was dried in a hot air dryer at 90 ° C., sandwiched between metal plates heated to 150 ° C., and pressed at a surface pressure of 0.15 kg / cm ² for 30 seconds. The obtained fiber sheet [1] was a smooth fiber sheet having a thickness of 1.5 mm and an apparent density of 0.22 g / cm ³ . Further, the crystallinity of the fiber sheet obtained by simultaneously shrinking and heat-treating the shrinkable polyester fiber web (A) was 35%.

Next, a polyurethane elastomer 10 having a 100% strength of 100 kg / cm ² obtained by reacting the fiber sheet [1] with polybutylene glycol having an average molecular weight of 2000, 4,4′-diphenylmethane diisocyanate and ethylene glycol. %, Carbon black 0.2
%, Nonionic surfactant 0.5% and dimethylformamide 89.3% were impregnated, immersed in a 40% dimethylformamide aqueous solution and treated for 30 minutes to coagulate the polyurethane elastomer, washed with water and dried. The obtained sheet material has a thickness of 1.5 mm and an apparent density of 0.30 g / cm.
The surface of ³ was smooth, and the wrinkles were fine, which was a good product.

In addition, according to a conventional method, a polyurethane elastomer (100% strength = 50 kg / cm) is added to the above-mentioned sheet material.
² , a solid content of 50 g / m ^{2 was} applied on the surface of the release paper to obtain a lightweight leather-like sheet material with a silver surface suitable for school bags, bags and the like.

Example 2 100% strength obtained by reacting the fiber sheet [1] of Example 1 with polybutylene glycol having an average molecular weight of 2000, 4,4′-diphenylmethane diisocyanate and ethylene glycol was 100 kg / cm ² . A composition liquid of 10% polyurethane elastomer, 0.2% carbon black, 0.5% nonionic surfactant, and 89.3% dimethylformamide was impregnated, and 15% of the above polyurethane, 0.2% carbon black, nonionic interface. A composition liquid of an activator 1% and dimethylformamide 83.8% in a liquid amount of 700 g /
m ^{2 was} applied, immersed in a 40% dimethylformamide aqueous solution and treated for 30 minutes to coagulate the polyurethane elastomer, washed with water and dried. The obtained sheet-like material had a porous polyurethane elastomer coating layer, and the surface of the coating layer of the sheet-like material was gravure-coated with a black ink prepared by adding a black colorant to the polyurethane elastomer to form a kerf. The leather-like sheet obtained by subjecting tonal embossing had a thickness of 1.8 mm and an apparent density of 0.32 g / cm ³ and had a smooth surface and fine creases and flexibility, and was good.

Comparative Example 1 Four shrinkable polyester fiber webs (A) of Example 1 were laminated and needle punched as in Example 1 to give a basis weight 2.
A laminated fiber sheet material having a weight of 30 g / m ² was obtained. This was dipped in hot water at 70 ° C. for 1 minute in the same manner as in Example 1 and squeezed with a mangle. Non-woven fabric is 3 in lengthwise direction compared to before heat treatment
8%, 45% in the lateral direction, and 66% in area. Then, the same surface smoothing treatment as in Example 1 was performed. The obtained fiber sheet has a thickness of 1.5 mm and an apparent density of 0.40 g.
It was a smooth fiber sheet of / cm ³ . The crystallinity of this fiber was 35%. A leather-like sheet was obtained by impregnating, coating, coagulating and surface finishing the polyurethane elastomer composition liquid in the same manner as in Example 2 except that this fiber sheet was used. The leather-like sheet thus obtained was heavy and hard with an apparent density of 0.45 g / cm ³ .

COMPARATIVE EXAMPLE 2 Two hollow polyethylene terephthalate fiber webs of Example 1 were laminated and needle punched in the same manner as in Example 1 to obtain a laminated fiber sheet. This laminated fibrous sheet was sandwiched between metal plates heated to 150 ° C., pressed under a surface pressure of 0.15 kg / cm ² , and treated for 30 seconds. The obtained fiber sheet has a thickness of 1.5 mm and an apparent density of 0.16 g /
It was a fibrous sheet with severe surface irregularities of cm ³ . A leather-like sheet was obtained by impregnating, coating, coagulating and surface finishing the polyurethane elastomer composition liquid in the same manner as in Example 2 except that this fiber sheet was used. Was obtained. This sheet-like product was a product with severe surface irregularities and rough wrinkles.

Comparative Example 3 The shrinkable polyethylene terephthalate fiber of Example 1 and the hollow polyethylene terephthalate fiber were mixed at a ratio of 50/50, and then the curd, cross lap, and pre-needle (40 punch / cm ² ) were passed through each step. Basis weight 120g
A fiber web of / m ² was obtained. A leather-like sheet material was obtained in the same manner as in Example 1 except that two fiber webs were laminated and used. This leather-like sheet was poor in surface smoothness.

Comparative Example 4 A leather-like sheet was obtained in the same manner as in Comparative Example 3, except that the surface pressure of the entangled nonwoven fabric during the surface smoothing treatment was 0.5 kg / cm ² . This leather-like sheet with a silver surface had good surface smoothness, but an apparent density of 0.40 g / cm ³
It was a high and heavy thing.

Example 3 In Example 1, instead of the hollow polyethylene terephthalate fiber, a single fiber fineness of 2.5 denier and a fiber length of 51 mm
A leather-like sheet material was obtained in the same manner except that the 6-nylon fiber was used. This leather-like sheet with a silver surface,
It had a thickness of 1.5 mm and an apparent density of 0.34 g / cm ³ and had a smooth surface and small wrinkles, and it was flexible. Example 1
Table 1 shows the area shrinkage ratio, apparent density, apparent wrinkles, and surface smoothness of No. 3 and Comparative Examples 1 to 4.

[0029]

[Table 1]

[0030]

As described above, according to the method of the present invention, the shrinkage ratio in hot water at 70 ° C. is at least 20.
%, And a web A made of shrinkable polyester fibers having a crystallinity of 20% or less and a web (B) made of fibers that do not substantially heat-shrink so that the web (A) sandwiches the web (B). After punch entanglement treatment, shrinkage of area shrinkage of 20 to 50% is applied, and crystallization treatment is performed at the same time as or after the shrinkage so that the crystallinity of the shrinkable polyester fiber becomes at least 30%. A sheet is obtained, and then the fiber sheet is impregnated with a solution or dispersion containing an elastic polymer as a main component, coagulated by a wet method or a dry method, and dried to finish a sheet-like product, thereby obtaining a surface smoothness. Is good and the wrinkles are fine,
A lightweight leather-like sheet material can be obtained.

Claims (1)

[Claims] 1. A web (A) made of a shrinkable polyester fiber having a shrinkage ratio of at least 20% in hot water at 70 ° C. and a crystallinity of 20% or less, and a fiber which does not substantially heat shrink. After laminating the web (B) so that the web (A) sandwiches the web (B) and performing needle punch entanglement treatment, the area shrinkage rate is 20% or more and 50% or more.
The following shrinkage is applied, and at the same time as or after the shrinkage, the shrinkable polyester fiber is crystallized so that the crystallinity of the shrinkable polyester fiber becomes at least 30% to obtain a fiber sheet, and the fiber sheet is mainly composed of an elastic polymer. A method for producing a flexible and smooth leather-like sheet material, which comprises: .