JP3391988B2 - Fiber sheet for artificial leather and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fibrous sheet used as a constituent substrate for artificial leather and the like, which has surface smoothness and a soft texture, and which is very excellent in tear strength and cut resistance. It is a thing.

[0002]

2. Description of the Related Art Conventionally, many proposals have been made for a fiber sheet for artificial leather having surface smoothness and a soft texture, and a fiber sheet for artificial leather having excellent tear strength, resulting in many materials. It has come. As a method for obtaining a fiber sheet having a soft texture, a water-soluble soluble resin such as polyvinyl alcohol (hereinafter referred to as PVA) is added to a fiber structure such as a fiber-entangled non-woven fabric when a substrate for artificial leather is prepared, and a fiber surface is obtained. Is covered with the resin, and after the elastic polymer is contained therein, the water-soluble soluble resin is dissolved and removed to form voids between the fiber and the elastic polymer, as disclosed in JP-B-45-18745. Japanese Patent Sho 45
It is proposed in Japanese Patent Application Laid-Open No. 1943, Japanese Patent Application Laid-Open No. 62-33885, Japanese Patent Application Laid-Open No. 62-149986 and the like. When this method is used, the surface of the fiber is covered with the water-soluble polymer, so that the fiber and the elastic polymer are prevented from adhering to each other and a soft texture is obtained.

As a method of improving the tear strength, Japanese Patent Publication No. 59-39550 discloses that a polycondensation cation activator by a polyamine derivative epihalohydrin is added to a fiber sheet made of an elastic polymer mainly composed of a nonwoven fabric and a polyurethane elastomer. Method, and JP-A 5-27
Japanese Patent Publication No. 9968 proposes a method of increasing the tear strength of a fiber sheet by increasing the apparent specific gravity of the fiber-entangled nonwoven fabric.

[0004]

Recently, in the field of artificial leather used for shoes and the like, high quality is demanded, and appearance,
It is required to satisfy all the sensitivities such as texture and surface smoothness and the physical properties such as tear strength, cut resistance and mechanical strength. Moreover, in recent years, particularly in the field of sports shoes, there is a tendency toward thinning and weight reduction, and thin and strong shoes are required. However, in the conventionally known artificial leather substrate made of an ultrafine fiber bundle and an elastic polymer, although the appearance, the feeling such as feeling is satisfactory, the tear strength, cut resistance, mechanical strength of the mechanical strength, There is a limit to the physical properties of the fibers constituting the fibrous substrate, and depending on the application, satisfactory physical properties have not been obtained.

As a means for improving the tear strength, even if the above-mentioned method of adding a polycondensation cation activator to a fiber sheet composed of a nonwoven fabric and a polyurethane elastomer or a method of increasing the apparent specific gravity of a fiber-entangled nonwoven fabric, The tear strength sheet was insufficient. Further, a method of using high-strength fibers as the entangled nonwoven fabric constituent fibers is conceivable, but there is a problem that the artificial leather substrate is inferior in terms of appearance, texture, surface smoothness, and other sensitivities, and it is currently used as an artificial leather substrate. Was never used. Furthermore, when a high-strength fiber is used as a non-woven sheet, the denier is thick, so the entanglement of the fibers is bad, and when the fiber is torn, it is in a bare state, and the effect of the physical properties of the high-strength fiber itself cannot be obtained. There was a problem that the surface smoothness was also poor.

The present invention is intended to be applied as a substrate for artificial leather without impairing the physical properties of the high-strength fiber.
By using a thick high-strength fiber that is poorly entangled with each other as an ultrafine fiber, the entanglement of the fibers is improved, and the physical properties of the high-strength fiber itself are utilized in the fiber sheet. That is, the present invention solves the above problems and provides a fiber sheet which is used as a constituent substrate of artificial leather, has a soft texture, and is extremely excellent in tear strength.

[0007]

[Means for Solving the Problems] That is, the present invention comprises a three-dimensionally entangled nonwoven fabric composed of molten liquid crystalline polyester fibers having a fineness of 0.5 denier or less and an elastic polymer present in the entangled space. It is a fiber sheet for artificial leather. In addition, the present invention comprises a liquid crystalline polyester and other polymer, and is composed of an ultrafine fiber generating fiber which becomes an ultrafine fiber having a fineness of 0.5 denier or less by removing the other polymer or peeling at the interface between both polymers. The three-dimensional entangled nonwoven fabric thus prepared is subjected to the following method (1) or (2),
(1) Performing a method of impregnating an elastic polymer and then making the ultrafine fiber-generating fibers into ultrafine fibers, and (2) a method of making the ultrafine fiber-generating fibers into ultrafine fibers and then impregnating the elastic polymer. It is a method of producing a fiber sheet for artificial leather by, particularly preferably, in this method, after the ultrafine fiber-generating fiber is made into ultrafine fibers, the fiber sheet is heat-treated in a nitrogen atmosphere, and then an elastic polymer is added. It is a method of impregnation.

The molten liquid crystallinity referred to in the present invention means an optical anisotropy in the molten phase. Such characteristics are
It can be easily identified by a known method, for example, by heating the sample placed on a hot stage under a nitrogen atmosphere to raise the temperature and observing the transmitted light. The molten liquid crystalline aromatic polyester used in the present invention is, for example, aromatic di-
Polymer, aromatic dicarboxylic acid, aromatic hydroxycarboxylic acid or the like, and preferably a polymer comprising a combination of repeating structural units shown in Chemical formulas 1 to 3.

[0009]

[Chemical 1]

[0010]

[Chemical 2]

[0011]

[Chemical 3]

Melting point (MP) of molten liquid crystalline polyester
Is 260 ° C to 380 ° C, especially 270 ° C to 350 ° C
Is preferred. The melting point referred to here is a differential scanning calorimeter (DSC; for example, TA3000 manufactured by METLER).
It is the peak temperature of the main endothermic peak observed in. Particularly preferably, the moiety consisting of the constitutional units of parahydroxybenzoic acid (a) and 2-hydroxy-6-naphthoic acid (b) is
It is a melt anisotropic aromatic polyester having a content of 80 mol% or more, and in particular, the ratio of the b component to the total amount of a and b is 5 to 45.
Aromatic polyesters which are mol% are preferred. The molten liquid crystalline polyester used in the present invention may appropriately contain titanium oxide, kaolin, silica, barium sulfate, carbon black, pigments, antioxidants, ultraviolet absorbers, light stabilizers and the like.

The fiber sheet of the present invention can be obtained, for example, by sequentially performing the following steps. An ultrafine fiber in which a molten liquid crystalline polyester is dispersed as an island component in a sea component polymer that can be dissolved or decomposed and removed from the fiber, and the molten liquid crystalline polyester is 0.5 denier or less by removing the sea component polymer. process for producing a microfine fiber-forming <br/> fibers comprising a step of producing an entangled nonwoven fabric made of the fibers, the step of temporarily fixing the non-woven fabric, dissolution removable resin optionally entangled nonwoven elastic polymer liquor was impregnated, the step of wet coagulation, process the process of our above denatured microfine fibers from ultrafine fiber-generating <br/> fibers may be in order is reversed. Furthermore, if the above steps are reversed, between the step and
It is preferable to insert a step of heat-treating the fiber sheet in a nitrogen atmosphere. Further, as a fiber in the above-mentioned step, the molten liquid crystalline polyester is divided by other polymer, and the molten liquid crystalline polyester has a denier of 0.5 denier or less by removing the other polymer or peeling at the interface of both polymers. It may be an ultrafine fiber-generating fiber that becomes an ultrafine fiber.

The ultrafine fibers made of the melted liquid crystalline polyester used in the present invention are produced from the ultrafine fiber generating fibers made of at least two kinds of polymers, that is, the melted liquid crystalline polyester and other polymers. For example, when the sea component polymer is dissolved or removed by decomposition with a solvent or a decomposing agent such as sodium hydroxide, the molten liquid crystalline polyester of the island component remains as ultrafine fibers, so-called extraction type fibers, or mechanically or by a treating agent. Examples of the fiber include a split-type fiber that is fibrillated into an ultrafine fiber.

The polymer component to be dissolved or removed by the extraction type fiber has different solubility or degradability in the solvent or the decomposing agent from the molten liquid crystalline polyester of the ultrafine fiber component and has a low compatibility with the molten liquid crystalline polyester. It is a polymer and has a lower melt viscosity or a lower surface tension than the molten liquid crystalline polyester under spinning conditions. For example, at least one selected from polymers such as polyethylene, polystyrene, polyethylene propylene copolymer, and modified polyester. One type of polymer may be mentioned.

Here, the ultrafine fibers made of the molten liquid crystalline polyester have a fineness of 0.5 denier or less. Since the molten liquid crystalline polyester is a rigid polymer, when the fineness of the ultrafine fibers made of the polyester is larger than 0.5 denier, the surface smoothness is poor when the fiber sheet is formed, and the fiber sheet becomes hard and flexible. It is difficult to obtain a texture. Furthermore, when the nonwoven fabric is torn, the tear strength is not so high. It is preferably 0.1 denier or less. When the ultrafine fibers are used, the molten liquid crystalline polyester fibers are entangled with each other, and the entanglement is enhanced. A typical example of the ultrafine fiber-generating fiber used in the present invention is a case where the fiber cross-sectional shape in the direction perpendicular to the fiber axis has a sea-island structure in which the molten liquid crystalline polyester is an island component and the other polymer is a sea component. A typical example is a case where the molten liquid crystalline polyester and the other polymer have an alternating laminated structure. The fiber of the present invention may be a mixed spun fiber (so-called chip blend fiber) or a composite spun fiber (so-called a fiber obtained by melting each polymer separately and merging both polymers in the vicinity of the spinneret). May be.

In the fibrous sheet of the present invention, since the fineness of the molten liquid crystalline polyester is 0.5 denier or less, even a fiber sheet made of only ultrafine fibers of the molten liquid crystalline polyester can have a sufficiently soft texture. A second ultrafine fiber may be added to obtain a softer material. As the polymer constituting the second ultrafine fiber, 6-
At least one polymer selected from nylon, melt-spinnable polyamides such as 66-nylon, polyethylene terephthalate, polybutylene terephthalate, melt-spinnable polyesters such as cationic dyeable modified polyethylene terephthalate Is mentioned. The second ultrafine fiber-generating fiber is also preferably a fiber that is made ultrafine by dissolving and removing or decomposing and removing one component, and the component that is dissolved or decomposed and removed is an ultrafine fiber-forming fiber made of molten liquid crystalline polyester. A polymer that is dissolved or removed by decomposition under the same conditions as the constituent polymer that is dissolved or removed by decomposition is preferable.

[0018] As a method for intermingling the microfine fiber-forming fibers and a second microfine fiber-forming fibers made of liquid crystalline polyester, stretched fibers after spinning, oiling, after imparting mechanical crimping, Examples thereof include a method of mixing cut staples using a blender, and a method of mixing fibers at the filament stage into a fiber bundle by compounding. The second ultrafine fibers are also preferably 0.5 denier or less. Here, the mixing ratio of the molten liquid crystalline polyester fiber and the second ultrafine fiber is 100/0 by weight.
The range is from 20/80 to 100/0 to 50/50. 20% by weight of molten liquid crystalline polyester
When the amount is less than the above, the high-strength property of the molten liquid crystalline polyester cannot be utilized, and the tear strength when formed into a fiber sheet is almost the same as when the molten liquid crystalline polyester fiber is not mixed.

The ultrafine fiber-generating fiber is opened with a card,
A random web or a cross-wrap web is formed through a weber, and the obtained fibrous web is laminated to have a desired weight and thickness. Then, a entangled nonwoven fabric is obtained by performing an entanglement treatment by a known method such as needle punching or high-speed fluid punching, or this fiber web is entangled with a knitted fabric using a water stream or the like, and a fiber entangled nonwoven fabric is obtained. And

If necessary, the fiber-entangled nonwoven fabric is impregnated with a water-soluble resin typified by polyvinyl alcohol, and the surface of the fiber is covered with the water-soluble resin, so that a water-soluble resin is added between the elastic polymer and the fiber to be applied later. Resin is present,
By removing the water-soluble resin by washing with water after applying the elastic polymer, the fibers and the elastic polymer do not substantially adhere to each other, and in such a fiber sheet, the fibers are free from the elastic polymer to some extent. Therefore, a very flexible fiber sheet can be obtained.

Next, the fiber-entangled nonwoven fabric is impregnated with an elastic polymer liquid and gelled by heating and drying, or it is immersed in a liquid containing a non-solvent of the elastic polymer and wet-solidified to make it porous. . Examples of the elastic resin impregnated here include at least one polymer diol selected from composite diols having an average molecular weight of 500 to 3000, such as polyester diol, polyether diol, polycarbonate diol, polyester polyether diol, and the like; At least one diisocyanate selected from aromatic, alicyclic, and aliphatic diisocyanates such as 4-diphenylmethane diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate, and two or more activities such as ethylene glycol and ethylenediamine At least 1 having hydrogen atoms
Examples thereof include polyurethanes obtained by reacting various kinds of low molecular weight compounds at a predetermined molar ratio and modified products thereof. Other than these, for example, an elastic polymer such as a polyester elastomer or an acrylic elastomer may be used, or a polymer composition obtained by mixing these may be used. However, the above-mentioned polyurethane is most preferably used from the viewpoints of flexibility, elastic recovery property, sponge forming property and the like.

The fiber entangled body is impregnated with an elastic polymer liquid obtained by dissolving or dispersing the elastic polymer as described above in a solvent or a dispersant, and the elastic polymer is treated with a non-solvent of the elastic polymer to wet-coagulate it to make it porous. The fibrous base material is obtained by a method of heating, or by heating and drying as it is to gel and make it porous. Additives such as a colorant, a coagulation regulator, an antioxidant, and a dispersant are added to the polymer liquid as needed. The ratio of the elastic polymer to the ultrafine-treated fibrous base material is such that the base material has a soft texture and elastic recoverability, and most importantly, as a solid content to form a highly smooth base material surface. The weight ratio is preferably 10% or more, and more preferably 30 to 50%. If the elastic polymer ratio is less than 10%, a dense elastic sponge cannot be formed.

Next, the fibrous substrate containing the elastic polymer is treated with a solvent or a decomposer for the dispersion medium component (sea component) of the ultrafine fiber-generating fiber which is a non-solvent for the ultrafine fibers and the elastic polymer. The ultrafine fiber-generating fiber is converted into an ultrafine fiber bundle by treatment or mechanical treatment.
Thereby, a fiber sheet having a structure in which ultrafine fibers are entangled with high-strength fibers is obtained. Further, in the present invention, the entangled nonwoven fabric obtained by performing the entanglement treatment is treated with a solvent or a decomposing agent for the dispersion medium component (sea component) of the ultrafine fiber-generating fiber to obtain a melted liquid crystalline polyester from the ultrafine fibers. It is also preferable to prepare a fiber entangled body of the following, heat-treat the fiber entangled body in a nitrogen atmosphere, and then impregnate the fiber entangled body with the elastic polymer liquid to obtain a fiber sheet. When the molten liquid crystalline polyester fiber is heat-treated in a nitrogen atmosphere, the strength and heat resistance are greatly improved.

As a specific condition for heat treatment, a temperature at which other ultrafine fibers are not melted or decomposed is preferable, and usually 2
A temperature of 20 ° C. or higher, particularly 240 ° C. or higher, and a temperature slightly lower than the temperature at which the nonwoven fabric constituent fibers are melted or decomposed is used. The heat treatment time is preferably in the range of 1 to 50 hours. When the heat treatment is carried out after impregnation with the elastic polymer, the elastic polymer is melted or decomposed under the heat treatment condition. Therefore, in the present invention, it is preferable to carry out after the impregnation with the elastic polymer. In addition, when heat treatment is performed in a state where the ultrafine fiber-generating fiber is not ultrafine, a low-melting polymer is usually used as the dispersion medium component, so the state of the entangled nonwoven fabric is significantly changed by melting at the heat treatment temperature. It is not preferable because it receives Therefore, it is preferable that the heat treatment is performed before the ultrafine fiber-generating fiber is ultrafine. The fiber sheet obtained by the present invention is excellent in surface smoothness, has a soft texture, and is also excellent in tear strength and cut resistance. An artificial leather with a silver surface is obtained by applying an elastic polymer represented by polyurethane to the surface of the fiber sheet of the present invention, and a suede-like artificial leather is obtained by buffing at least one surface of the fiber sheet of the present invention. Is obtained.

[0025]

EXAMPLES The present invention will now be described with reference to specific examples, but the present invention is not limited to these examples.
In addition, in this invention, a physical-property value is measured on condition of the following. 1. Unit weight (g / m ² ) The obtained fiber sheet was cut into 10 cm squares, and the weight W thereof was measured by an electronic balance (AE180 manufactured by Metra) to obtain W /
It was determined by 0.01. 2. Thickness (mm) A thickness measuring device (Peacock G manufactured by OZAKI MFG CO. LTD) was used to measure 10 points, and the average was obtained. 3. The density (g / cm ³ ) (unit weight / thickness) × 1,000 was calculated.

4. Breaking length (km) A sample with a width of 25 cm was sandwiched between chucks at intervals of 10 cm, and the strength when broken at a head speed of 100 mm / min was obtained using a universal testing machine (manufactured by Instron Co.). Divided by 25 and calculated. 5. Specific tear strength (m ² ) A 10 cm long cut was made in the center of a sample having a width of 4 cm, and the tear strength at a head speed of 100 mm / min was divided by the basis weight using the universal testing machine. 6. Cut resistance (m ² ) A sample with a width of 1 cm was passed through the blade of a cutter set at an angle of 10 degrees, and the strength when the sample was cut at a head speed of 50 mm / min using the universal testing machine was divided by the basis weight. I asked.

Examples 1 to 4 and Comparative Example 1 As the island component polymer, 50% by weight of a molten liquid crystalline polyester polymerized from 73 mol% of parahydroxybenzoic acid and 27 mol% of 2-hydroxy-6-naphthoic acid, sea High-density polyethylene 50% by weight is mixed with the ingredients and the temperature is 305 ° C.
Then, the sea-island type ultrafine fiber-generating type fibers were mixed and spun, and mechanically crimped and cut into 51 mm to obtain staples (A). The fineness of the ultrafine fiber-forming fiber was 5 denier, and the fineness of each island component was about 0.003 denier. 50% by weight of nylon-6 as an island component and 50% by weight of low-density polyethylene as a sea component were mixed and spun at 290 ° C. to form ultra-fine fibers of sea-island type fiber, drawn in hot water at 80 ° C., and machined. It was crimped and cut into 51 mm to obtain a staple (B). The fineness of this ultrafine fiber-generating fiber was 9 denier, and the fineness of each island component was 0.002 denier. The mixing ratio of these two types of staples is A / B = 1.
The cotton was mixed so as to be 00/0 to 20/80. This mixed cotton fiber was applied to a card to form a web by a cross wrap method, then needle punched and pressed with a calendar roll to obtain an entangled nonwoven fabric having a smooth surface. This entangled non-woven fabric is impregnated with a 13% dimethylformamide solution of polyether polyurethane and immersed in a dimethylformamide / water mixture for wet coagulation, and then the sea component polymer in the mixed fiber is eluted and removed in hot toluene. Then, a fiber sheet was obtained. The weight ratio of the elastic polymer in the fiber sheet was 42%. Table 1 shows the physical properties of the obtained fiber sheet.

Comparative Example 2 Only the molten liquid crystalline polyester used in Example 1 was spun alone and subjected to mechanical crimping to cut it into 51 mm to obtain a staple made of only the molten liquid crystalline polyester. The fineness was 2.5 denier. An entangled nonwoven fabric was prepared in the same manner as in Example 1 using only the staple. This entangled nonwoven fabric was impregnated with the same polyurethane solution as in Example 1 and solidified to obtain a fiber sheet. Table 1 shows the physical properties of the obtained fiber sheet.

Example 5 A 13-layer laminated split type ultrafine fiber generating fiber was composite-spun using the molten liquid crystalline polyester and high density polyethylene used in Example 1 and mechanically crimped and cut into 51 mm. And made it staple. The fineness of ultra-fine fiber generation type fiber is 5
It was denier. The ultrafine fiber obtained from this fiber had a thickness of about 0.3 denier. A fiber sheet was obtained in exactly the same manner as in Example 1 using only this staple. Table 1 shows the physical properties of the obtained fiber sheet.

Example 6 The entangled non-woven fabric obtained in Example 1 was subjected to elution and removal of the sea component in the mixed fiber in hot toluene, and then was carried out in a nitrogen atmosphere at 26
Heat treatment was performed at 0 ° C. for 10 hours. The heat-treated non-woven fabric was impregnated with a polyurethane solution mainly composed of polyether polyurethane and wet-coagulated to obtain a fiber sheet. Table 1 shows the physical properties of the obtained fiber sheet.

Example 7 Instead of the molten liquid crystalline polyester used in Example 1, the molar ratio of the structural units C to F shown in Chemical formula 3 was C: D: E: F.
= 60: 20: 15: 5, a molten liquid crystalline polyester polymer is used, and a sea-island type ultrafine fiber-generating fiber is mixed and spun at a head temperature of 340 ° C. and mechanically crimped to 51 mm.
It was cut into staples. The fineness of ultra-fine fiber generation type fiber is 5 denier and the fineness of individual island components is about 0.003.
It was denier. Using this staple, a fiber sheet was obtained in the same manner as in Example 1. Table 1 shows the physical properties of the obtained fiber sheet.

Example 8 A fiber sheet was obtained in the same manner as in Example 6 except that the molten liquid crystalline polyester staple used in Example 7 was used. Table 1 shows the physical properties of the obtained fiber sheet.

[0033]

[Table 1]

[0034]

EFFECT OF THE INVENTION The fiber sheet obtained by the present invention has a soft texture and excellent surface smoothness, and has excellent tear strength and cut resistance, and is suitable for shoes and gloves. It can be used as a base for artificial leather such as.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-58-89651 (JP, A) Fukukaihei 4-25842 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) D06N 3/00-3/18

Claims (3)

(57) [Claims] 1. A fiber sheet for artificial leather comprising a three-dimensionally entangled nonwoven fabric made of melted liquid crystalline polyester fibers having a fineness of 0.5 denier or less and an elastic polymer present in the entangled space. 2. An ultrafine fiber-generating fiber comprising a melted liquid crystalline polyester and another polymer, and by removing the other polymer or peeling at the interface between both polymers, an ultrafine fiber having a fineness of 0.5 denier or less is formed. The three-dimensional entangled nonwoven fabric thus prepared is subjected to the following method (1) or (2),
(1) An artificial polymer is impregnated with an elastic polymer and then the ultrafine fiber-generating fiber is made into an ultrafine fiber, and (2) an ultrafine fiber-generating fiber is made into an ultrafine fiber and then impregnated with an elastic polymer. A method for manufacturing a fiber sheet for leather. 3. The method according to claim 2, wherein after the ultrafine fiber-generating fibers are made into ultrafine fibers, the fiber sheet is heat-treated in a nitrogen atmosphere and then impregnated with an elastic polymer.