JPH10195782A - Flame retardant fibrous sheet and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the subject sheet, capable of imparting flame retardance without deteriorating fiber physical properties and excellent even in durability of the flame retardance performances by the presence of a flame retardant in a specified state in a porous textile fabric. SOLUTION: This flame retardant fibrous sheet is produced by including a porous elastic polymer in a fabric of porous fibers and making a flame retardant (preferably fine flame retardant particles having <=1μm average particle diameter) in spaces of the porous fibers and in the interior of the porous elastic polymer. The resultant sheet is suitable for the interior field, especially upholsteries, etc., on seats for automobiles, seats for rolling stocks and sofas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fabric comprising porous fibers conventionally used as artificial leather and a fiber sheet comprising a porous elastic polymer contained in the fabric. The present invention also relates to a flame-retardant sheet made of porous fibers, which has excellent durability and is suitable for applications requiring flame retardancy, such as in the interior field, particularly for automobile seat materials.

[0002]

2. Description of the Related Art Conventionally, synthetic fibers, particularly polyester fibers and polyamide fibers, are indispensable as materials for clothing, interiors, etc. due to their excellent dimensional stability, weather resistance, mechanical properties and durability. It has become. However, depending on the intended use, it is desired to further provide a special function. For example, in the field of interiors, in particular, in the field of artificial leather used for railway vehicle seats, automobile seats, and the like, it is extremely important to impart flame retardancy.

[0003] Conventionally, a cloth having an elastic polymer in an entangled space of a non-woven fabric has been used as a base material of artificial leather. As a method for imparting flame retardancy to this cloth, a flame retardant is subjected to a post-processing method or the like. A method of adhering to the surface of fibers and an elastic polymer, a method of laminating a sheet having flame retardancy on one side, and a method of kneading flame-retardant fine particles into a fiber-forming thermoplastic polymer.

When a flame retardant is applied to an artificial leather having an elastic polymer in an entangled space of a nonwoven fabric by a post-processing method,
In addition to deteriorating the feel of the sheet, it is impossible to obtain a sheet having good flame retardancy and durability. Further, in the method of laminating a sheet having flame retardancy on the back surface, a difference occurs in the flame retardancy between the front surface and the back surface, and the texture of the sheet is impaired. As a method of kneading the flame retardant into the thermoplastic polymer, a flame retardant containing a phosphorus-based or halogen-based compound as an active ingredient, polyethylene, polypropylene, a polyethylene-polypropylene copolymer, kneaded into a molding material such as polystyrene, and A method of performing molding is generally used. However, the mixing of the flame retardant with polyamide polymers such as nylon 6, nylon 66 and nylon 610 and polyester polymers such as polyethylene terephthalate and polybutylene terephthalate causes the stability of the flame retardant and polymer at the melt spinning temperature. In view of the above, there are restrictions on the setting of the spinning temperature, the selection of the polymer and the flame retardant, and the like, resulting in a problem in productivity.

[0005]

As described above, the method of kneading a flame retardant into fibers may be applicable when the flame-retardant conjugate fiber is a fiber made of regular denier, but it may have two or more components. When applied to fibers having a myriad of hollow parts with fine interiors, such as porous fibers obtained by extracting one or more components of a composite or mixed spun fiber consisting of a thermoplastic polymer of Due to the relationship between the particle size of the fine particles and the resin cross-sectional area of the porous fiber, the physical properties of the fiber are significantly reduced, and a material that can withstand practical use cannot be obtained.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fabric comprising porous fibers obtained by extracting one or more components of a composite or mixed spun fiber comprising two or more thermoplastic polymers and a porous elastic material contained in the fabric. An object of the present invention is to provide a flame-retardant fiber sheet having excellent durability, in which a fiber sheet made of a united material is provided with flame-retardant performance without deteriorating the physical properties of the fiber, and the flame-retardant performance is not greatly reduced even after repeated cleaning. It is in.

[0007]

That is, the present invention relates to a fabric comprising porous fibers and a fiber sheet comprising a porous elastic polymer contained in the fabric. A flame-retardant fiber sheet characterized in that a flame retardant is present inside the polymer. The present invention also relates to a fabric comprising sea-island structural fibers comprising two or more types of incompatible polymers, and a fiber sheet comprising a porous elastic polymer contained in the fabric. A method for producing a fiber sheet comprising a porous fiber and an elastic polymer by removing a polymer, wherein a fiber in which a flame retardant is added to an island component polymer is used as the sea-island structural fiber. This is a sheet manufacturing method. In the present invention, the flame retardant is preferably flame-retardant fine particles having a particle diameter of 1 μm or less.

[0008] The flame-retardant fiber sheet of the present invention will be described by taking the case of artificial leather as an example. The flame-retardant fiber sheet of the present invention can be obtained by, for example, combining the following steps. That is, (1) a step of producing a sea-island structure fiber in which a flame retardant is kneaded into an island component constituting polymer, (2) a step of producing an entangled nonwoven fabric made of the fiber, and (3) a temporary nonwoven fabric as required. Fixing; (4) impregnating the entangled nonwoven fabric with an elastic resin liquid and solidifying to form a dense foam; (5) removing island components from the fiber to modify it into porous fiber; Are sequentially obtained.

The sea-island structural fiber used in the present invention is obtained by composite or mixed spinning of two or more kinds of thermoplastic polymers having no compatibility. The sea component polymer is a polymer exhibiting sufficient fiber properties such as strength, for example, a polyamide polymer such as nylon 6, nylon 66 or nylon 610, or a polyester polymer such as polyethylene terephthalate or polybutylene terephthalate.
And the like must be a melt-spinnable polymer. on the other hand,
The island component polymer is a polymer having a different solubility or decomposability to a solvent or a decomposer from the sea component polymer (having higher solubility or degradability than the sea component polymer) and having low compatibility with the sea component polymer. A polymer having a higher melt viscosity and a lower surface tension than the sea component polymer under spinning conditions, for example, at least one polymer selected from polymers such as polyethylene, polystyrene, polyethylene propylene copolymer, and modified polyester It is. For example, polystyrene can be easily extracted with toluene, polyethylene can be easily extracted with tricrene, and modified polyesters such as sodium sulfoisophthalate copolymerized polyethylene terephthalate can be decomposed and removed with alkali. By extracting or decomposing and removing the island component polymer from the sea-island structure fiber, a porous fiber is obtained. The porous fiber is a fiber having a large number of hollow portions extending in the fiber length direction inside the fiber, and the hollow portion may be independent of or connected to an adjacent hollow portion.

[0010] In the composite or mixed spun sea-island structure fiber of the present invention, the flame retardant is added to the island component polymer extracted or decomposed and removed. It will be present in the hollow inside, preventing the flame retardant from falling off from the fiber sheet,
Further, the porous fiber and the dense elastic resin foam (porous portion) existing in the entangled space serve as a filter, and it is possible to prevent the flame retardant from falling off from the fiber sheet. Further, since the flame retardant exhibits flame retardancy through the filter, most of the added flame retardant can effectively act. Therefore, in the present invention, it is also important that the fabric contains the elastic polymer in a porous state.

As the flame retardant, flame-retardant fine particles containing a phosphorus-based or halogen-based compound as an active ingredient and having an average particle diameter of 2 μm or less, particularly 1 μm or less and 0.1 μm or more are preferably used. It is desirable that the flame-retardant fine particles have thermal stability when the sea-island structural fiber is melt-spun and stability to a polymer. Generally, flame retardants containing a phosphorus-based or halogen-based compound as an active ingredient are polyamide polymers such as nylon 6, nylon 66, and nylon 610, which are sea component polymers of the present invention, and polyester polymers such as polyethylene terephthalate and polybutylene terephthalate. It is known that it has low reactivity with hydrocarbon polymers such as polyethylene, polystyrene and polyethylene propylene copolymer used in the island component polymer of the present invention. Therefore, when the flame-retardant fine particles are kneaded into an island component composed of a hydrocarbon-based polymer such as polyethylene, polystyrene, or polyethylene-propylene copolymer to melt-spin the sea-island structural fiber, nylon 6, nylon 66, nylon 610, or the like is used. Polyamide-based polymer, polyethylene terephthalate, it is preferable that the contact time between the sea component resin such as polyester-based polymer such as polybutylene terephthalate and the flame-retardant fine particles is shorter, and a lamination type spinning method is desirable as compared with mixed spinning,
Further, a spinning method using a needle pipe type nozzle is desirable.

It is desirable that the flame-retardant fine particles do not cause thermal decomposition at the temperature at which the sea-island structure fiber is melt-spun. Further, the solvent in the step of extracting and removing the island component of the sea-island structure fiber to express the porous fiber is used. Alternatively, it is desirable that there is no solubility or decomposability with respect to a decomposing agent. If the particle diameter of the flame-retardant fine particles exceeds 2 μm, the pack pressure increases during melt spinning or the yarn breaks, which is not preferable. On the other hand, if the thickness is less than 0.1 μm, the amount of water flowing out during removal of the island component polymer increases, which is not preferable.

[0013] The sea-island structural fiber is defibrated with a card, a web is formed through a webber, and the obtained fiber web is laminated to a desired weight and thickness.
For example, entanglement is performed by a needle punch method, high-pressure water entanglement, or the like to form a nonwoven fabric, or the staple is entangled with a knitted fabric by using a water flow or the like to obtain a fabric. When used for applications other than leather-like sheets, sea-island structural fibers can be used as spun yarns or in the form of multifilament yarns as fabrics such as knitted fabrics.

Next, the cloth is impregnated with an elastic resin liquid and heated and dried to form a gel, or the cloth is dipped in a liquid containing a non-solvent of the elastic resin and wet-solidified to form a dense foam of the elastic polymer. Form a sponge (porous state). As the elastic polymer to be impregnated here, for example, an average molecular weight of 5
At least one polymer diol selected from the group consisting of a complex diol such as polyester diol, polyether diol, polycarbonate diol or polyester polyether diol, and 4,4 ′
Diphenylmethane diisocyanate, isophorone diisocyanate, at least one diisocyanate compound selected from aromatic, alicyclic or aliphatic diisocyanates such as hexamethylene diisocyanate, and two or more diisocyanate compounds such as ethylene glycol and isophorone diamine. Polyurethanes obtained by reacting at least one type of low-molecular compound having an active hydrogen atom with a predetermined molar ratio and modified products thereof are also included. In addition, polyester elastomers, hydrogenated styrene-isobutylene block copolymers And an elastic polymer such as an acrylic polymer. Further, an elastic polymer composition obtained by mixing these may be used. However, the above polyurethane is preferably used in view of flexibility, elastic recovery, sponge forming property, durability and the like.

A polymer solution obtained by dissolving or dispersing the above-mentioned elastic polymer in a solvent or dispersant is impregnated into a cloth and treated with a non-solvent of a resin to form a sponge by wet coagulation or heat drying as it is. Then, a sponge is formed by gelation, or a foaming agent is added to the elastic polymer, and an elastic polymer-containing fiber sheet is obtained by a method of foaming the foam. If necessary, additives such as a colorant, a coagulation regulator, an antioxidant, and a dispersant may be added to the elastic polymer liquid. The proportion of the elastic polymer in the fibrous substrate is at least 10% by weight as solid content, preferably 3%.
It is in the range of 0 to 50%. If the elastic polymer ratio is less than 10%, a dense elastic sponge is not formed, and the flame retardant tends to fall off after the generation of the porous fibers.

Next, the fiber sheet containing the elastic polymer is treated with a chemical which is a non-solvent for the sea component of the sea-island structure fiber and the elastic polymer and which is a solvent or a decomposer for the island component of the sea-island structure fiber. This generates porous fibers.
In this step, the island component polymer is removed from the fiber sheet, but the flame retardant kneaded in the island component polymer is not removed in a significant amount and remains in the fiber sheet in such a manner that it does not easily fall off. In the present invention, as the degree of hollow formed by removing island components from sea-island structural fibers,
40% or more and 70% or less of the fiber cross section are preferred in terms of leather-like flexibility and strength. The average diameter of the hollow part is 5
μm or less, particularly 2 μm or less, is preferred in terms of leather-like texture and flame retardant retention. The amount of the flame retardant contained in the fabric (in the case of a flame retardant supported on a carrier, the amount including the weight of the carrier) is 0.1% by weight or more, especially 0% by weight, based on the weight of the fiber sheet. From 0.3% by weight to 5% by weight is preferred in terms of sufficient flame retardancy and economy.

Conventionally, as a method of applying a flame retardant to a fiber sheet, a method of impregnating a cloth with a liquid containing a flame retardant and drying the cloth is generally used.
When the fiber is a porous fiber, the flame retardant hardly penetrates into the pores of the porous fiber, and most of the flame retardant exists on the outer surface of the fiber or the outer surface of the sponge.
In such a case, the flame retardant easily falls off,
A durable flame retardant effect cannot be obtained. Also, in order to prevent the flame retardant from falling off, there is a method of kneading the flame retardant into the binder resin and impregnating the cloth with the binder resin liquid. In addition, the flame retardant is covered with the resin, so that the flame retardancy is greatly reduced. Further, since the resin is also filled in the cloth, disadvantages such as impairing the flexibility of the cloth occur, but in the case of the present invention, Does not have such disadvantages.

The flame-retardant fiber sheet of the present invention may be provided with a resin layer on its surface, or by melting and smoothing the surface of the fiber sheet, and further imparting leather-like surface irregularities to the surface of the fiber sheet. Leather-like sheet can be provided. Of course, in this case, it is also possible to carry out simultaneously when the elastic polymer is contained in the fabric. Such a leather-like sheet can be used for applications such as shoes, bags, accessories, clothing, and the like. Especially in applications where flame retardancy is required, such as automotive seats, railway vehicle seats, interior goods, etc.
The fiber sheet of the present invention is suitable for applications requiring strength.

[0019]

EXAMPLES Next, the present invention will be described specifically with reference to Examples.
The present invention is not limited to these examples. In the examples, parts and percentages relate to weight unless otherwise specified. The evaluation of the flame retardancy in the examples was measured according to the following method. Test method: Automotive interior material test method FMVSS-30
2 The tear strength of the sheet in the examples is JIS L-109.
It was measured by A-1 (single tongue method) of 66.15.1.

Examples 1-2 A low-density polystyrene master chip containing 6-nylon (sea component), low-flow polystyrene (island component), and a phosphorus-based inorganic flame retardant 20% [Daifunen PEM PSH-922;
The average particle size of 0.5 μm manufactured by Dainichi Seika Kogyo Co., Ltd.] is mixed at a ratio shown in Table 1 to obtain a sea-island type mixed spun fiber by melt spinning, which is 2.5 times in 70 ° C. hot water. After applying a fiber oil agent, drying by applying mechanical crimping, cutting to 51 mm to form staples, and applying a basis weight of 60 by a cross lap method.
A web of 0 g / m ² was formed, followed by needle punching of about 500 punches / m ² alternately from both sides, further heating, and pressing with a calender roll to produce an entangled nonwoven fabric with a smooth surface. The basis weight of this entangled nonwoven fabric was 550 g / m ² , and the apparent specific gravity was 0.285. The entangled nonwoven fabric is impregnated with a dimethylformamide (DMF) solution having a solid content concentration of 20% of polyurethane mainly composed of polytetramethylene ether-based polyurethane, immersed in a DMF / water mixture, and wet-solidified. The island component in the mixed spun fiber was eluted and removed in toluene to develop a porous fiber, and a 1.5 mm thick fiber sheet having strong tear strength and flame retardancy was obtained. The raw yarn immediately after spinning had a yellow tint due to the reaction between the flame retardant and the 6-nylon of the island component, and a slight yellowing was also observed in the fiber sheet. The weight ratio of fiber to polyurethane in the fiber sheet was about 5: 2. When the fiber cross section of the obtained fiber sheet was observed with a microscope, it was confirmed that a large amount of the flame retardant was present in the pores in the fiber and on the inner surface of the porous elastic polymer. Table 2 shows the results of evaluating the tear strength and flame retardancy of each of the obtained fiber sheets.

Examples 3 and 4 Low-density polystyrene master chips containing 6-nylon for the sea component, low-flow low-density polystyrene for the island component and 20% of a phosphorus-based inorganic flame retardant [Daifunen PEM PSH-9
22; manufactured by Dainichi Seika Kogyo Co., Ltd., average particle size: 0.5 μm] at a ratio shown in Table 1 using a lamination type nozzle to produce a 50-island core-sheath fiber. Example 1 using this fiber
And a fiber sheet was obtained in the same manner as in Nos. 1 to 2. The raw yarn immediately after spinning had a yellow tint due to the reaction between the flame retardant and the 6-nylon of the island component, and a slight yellowing was also observed in the fiber sheet. The presence state of the flame retardant was determined in Example 1 above.
As a result of observation in the same manner as in Example 1, it was in the same state as in Examples 1 and 2. Table 2 shows the results of evaluating the tear strength and flame retardancy of each of the obtained fiber sheets.

Examples 5 to 6 Low-density polystyrene master chips containing 6-nylon for the sea component and 20% of low-flow low-density polystyrene and phosphorus-based inorganic flame retardant for the island component [DAIFUNEN PEM PSH-9
22; manufactured by Dainichi Seika Kogyo Co., Ltd., average particle size: 0.5 μm] at a ratio shown in Table 1, and a 50 island core-sheath fiber was produced using a needle pipe type nozzle. Using this fiber, a fiber sheet was obtained in the same manner as in Examples 1 and 2 above. Yellowing due to the reaction between the flame retardant and 6-nylon was not observed in the raw yarn immediately after spinning or in the state of the fiber sheet. When the presence state of the flame retardant was observed in the same manner as in Example 1, the state was the same as in Examples 1 and 2.
Table 2 shows the results of evaluating the tear strength and flame retardancy of each of the obtained fiber sheets.

Comparative Example 1 A fiber sheet was produced under the same conditions as in Example 1 except that no flame retardant master chip was used. Table 2 shows the results of evaluating the tear strength and flame retardancy of the obtained fiber sheet.

Comparative Examples 2-3 The phosphorus-based inorganic flame retardant used in Example 1 was kneaded into 6-nylon to prepare a master chip containing 20% of the flame retardant. Using 6-nylon and the flame-retardant master chip as the sea component and low-flow polystyrene as the island component in the proportions shown in Table 1, 50 needle core-sheath fibers were produced using a needle pipe type nozzle. Using this fiber, a fiber sheet having a thickness of 1.50 mm was produced under the conditions of Examples 1 and 2. The raw yarn immediately after spinning had a yellow tint due to the reaction between the flame retardant and the 6-nylon of the island component, and a slight yellowing was also observed in the fiber sheet. Each of the obtained fiber sheets had some flame retardancy, but had a low tear strength. When the presence state of the flame retardant was observed in the same manner as in Example 1, almost no flame retardant was found in the pores of the fibers. Table 2 shows the results of evaluating the tear strength and flame retardancy.

Comparative Examples 4 and 5 Using a 6-nylon and a flame-retardant master chip for the sea component and a low-flowable polystyrene for the island component at the ratios shown in Table 1, 50-core core-sheath fibers were produced using a lamination type nozzle. did. 1.50 mm thick under the conditions of Examples 1-2 using this fiber
Was produced. The raw yarn immediately after spinning had a yellow tint due to the reaction between the flame retardant and the 6-nylon of the island component, and a slight yellowing was also observed in the fiber sheet. Each of the obtained fiber sheets had flame retardancy for the time being, but had low tear strength. When the presence state of the flame retardant was observed in the same manner as in Example 1, almost no flame retardant was found in the pores of the fibers. Table 2 shows the results of evaluating the tear strength and flame retardancy.

[0026]

[Table 1]

[0027]

[Table 2]

The sheet of the present invention has excellent flame retardancy, excellent tear strength, and extremely excellent durability of the flame retardancy. The fiber sheet of the present invention is extremely excellent as a base layer of artificial leather, and is suitable for applications requiring strength and flame retardancy such as automobile seats, railcar seats, and sofa upholstery. Further, the sheet of the present invention can be used for general uses other than artificial leather.

Claims (4)

[Claims] 1. A fabric made of porous fibers and a fiber sheet made of a porous elastic polymer contained in the fabric, wherein a flame retardant is present in a space in the porous fibers and inside the porous elastic polymer. A flame-retardant fiber sheet characterized by the following. 2. The flame-retardant fiber sheet according to claim 1, wherein the flame retardant is a flame-retardant fine particle having a particle diameter of 1 μm or less. 3. A fabric comprising sea-island structural fibers comprising two or more types of incompatible polymers and an island component of said fibers from a fiber sheet comprising a porous elastic polymer contained in said fabric. A method for producing a fiber sheet comprising a porous fiber and an elastic polymer by removing a polymer, wherein a fiber in which a flame retardant is added to an island component polymer is used as the sea-island structural fiber. A method for producing a fiber sheet. 4. The method according to claim 3, wherein the flame retardant is flame-retardant fine particles having a particle diameter of 1 μm or less.