JPH10183479A - Flame-resistant sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a flame-resistant sheet excellent in flame resistance, also in tearing strength, and further in endurance of the flame resistance extremely. SOLUTION: This method of producing a flame resistance sheet is to use a fiber having islands in a sea type structure in which fine particle state flame resisting agent is added on a polymer of the sea component, in a method of producing a fibrous sheet consisting of bindle of extremely fine fibers and an elastic polymer by removing the sea component polymer from the fibrous sheet consisting of a cloth consisted by an island in a sea structure fiber consisting of two or more kinds of polymers having no compatibility with each other, and a porous elastic polymer contained in the cloth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber sheet made of ultrafine fibers, which has an excellent flame retardant effect and durability, and is used for applications requiring flame retardancy, such as in the interior field, particularly for automobile seat materials. The present invention relates to a flame-retardant sheet made of ultrafine fibers, which is suitable for the above.

[0002]

2. Description of the Related Art Conventionally, synthetic fibers, particularly polyester fibers and polyamide fibers, are indispensable as materials for clothes and interiors because of 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, particularly in the field of artificial leather used for railway vehicle seats, automobile seats, and the like, it is extremely important to provide flame retardancy.

[0003] Conventionally, as a base layer of artificial leather, a cloth having an elastic polymer in an entangled space of a microfiber nonwoven fabric has been used, and when a resin layer is applied to the surface of this cloth, a so-called artificial leather with a silver surface layer is used. Further, when the surface of the cloth is fluffed, a so-called suede-like artificial leather is obtained. As a method of imparting flame retardancy to such an artificial leather substrate layer, a method of attaching a flame retardant to the surface of fibers and an elastic polymer by a post-processing method or the like, a method of laminating a sheet having flame retardancy on the back surface A method of kneading flame-retardant fine particles into a fiber-forming thermoplastic polymer has been used.

[0004] 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, the texture of the artificial leather sheet is deteriorated and the sheet of the suede-like sheet whose surface is raised is improved. In this case, the dense nap state on the surface is collected by the flame retardant treatment, and the appearance is deteriorated. 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 a flame retardant into a thermoplastic polymer, a flame retardant containing a phosphorus-based or halogen-based compound as an active ingredient is kneaded into a molding material such as polyethylene, polypropylene, a polyethylene-polypropylene copolymer, or polystyrene. In general, a method of imparting a flame retardant effect is performed. However, nylon 6, nylon 6
6. The kneading of the flame retardant into a polyamide polymer such as nylon 610 and a polyester polymer such as polyethylene terephthalate and polybutylene terephthalate is performed by setting the spinning temperature in view of the stability of the flame retardant and the polymer at the melt spinning temperature. In addition, there are restrictions on the selection of the polymer and the flame retardant, and there is a problem in productivity.

[0006]

As described above, the method of kneading a flame retardant into fibers has a possibility of being applied when the flame-retardant conjugate fibers are regular denier, that is, fibers having 0.2 denier or more. However, it is not applicable to extremely thin fibers. For example, in the case of suede-like artificial leather in which thin fibers are important, setting the fineness of the fibers to 0.1 denier or less is necessary in order to obtain a dense and luxurious fiber nap, and in terms of texture. In order to obtain a feeling of fulfillment of natural leather, it is necessary to knead the flame-retardant fine particles into such ultrafine fibers. Physical properties are significantly reduced, and a material that can be used practically cannot be obtained.

[0007] An object of the present invention is to significantly reduce fiber properties to ultrafine fibers having a single denier of 0.1 denier or less obtained by removing one or more components of a composite or mixed spun fiber comprising two or more thermoplastic polymers. An object of the present invention is to provide a flame-retardant sheet having excellent durability, in which the flame-retardant performance is provided without causing the flame-retardant performance to be greatly reduced even after repeated cleaning and the like.

[0008]

In other words, the present invention relates to a fabric comprising a microfine fiber bundle and a fiber sheet comprising a porous elastic polymer present in the fabric, wherein a void inside the microfine fiber bundle and the porous sheet are provided. A flame-retardant sheet characterized in that a flame retardant is present in the pores inside the polyelastic polymer. Further, the present invention provides 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 comprising a sea component of the fibers. In a method for producing a fiber sheet comprising an ultrafine fiber bundle and an elastic polymer by removing a polymer,
A method for producing a flame-retardant sheet, characterized in that a fiber in which a flame retardant is added to a sea component polymer is used as the sea-island structural fiber. In this production method, the fiber cross section of the sea-island structure fiber may have a structure in which the sea component polymer is divided into a plurality by the island component polymer. In the present invention, the flame retardant is preferably flame-retardant fine particles having a particle diameter of 1 μm or less.

The flame-retardant sheet of the present invention will be described by taking the case of artificial leather as an example. The flame-retardant sheet of the present invention can be obtained, for example, by combining the following steps (1) to (5). That is, (1) a step of producing a sea-island structural fiber in which a flame retardant is kneaded with a polymer constituting a sea component, (2) a step of producing an entangled nonwoven fabric made of the fiber, and (3) a temporary fixing of the nonwoven fabric as necessary. (4) a step of impregnating the entangled nonwoven fabric with an elastic resin liquid and coagulating to form a dense foam; and (5) a step of removing a sea component polymer from the fibers to modify them into ultrafine fiber bundles. , In order, the flame retardant sheet of the present invention can be obtained.

The islands-in-the-sea structure fiber used in the present invention can be obtained by subjecting two or more kinds of incompatible thermoplastic polymers to composite spinning or mixed spinning. The island component polymer is preferably a polymer exhibiting sufficient fiber properties such as strength and a polymer having a higher melt viscosity and a lower surface tension than the sea component polymer under spinning conditions. For example, nylon 6, nylon 66, It must be a melt-spinnable polymer such as a polyamide polymer such as nylon 610 and a polyester polymer such as polyethylene terephthalate and polybutylene terephthalate.

On the other hand, the sea component polymer is different from the island component polymer in solubility or decomposability to a solvent or a decomposer (has higher solubility or decomposability than the island component polymer), and is compatible with the island component polymer. And at least one polymer selected from polymers such as polyethylene, polystyrene, polyethylene propylene copolymer, and modified polyester. 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. Then, by extracting or decomposing and removing the sea component polymer from the sea-island structure fiber, an ultrafine fiber bundle can be obtained. In the present invention, the sea-island structural fiber may be such that, in the cross section of the fiber, the sea component may be divided into a plurality of portions by the island component polymer. Fibers such as The island component polymer may be connected endlessly in the fiber length direction or may be discontinuous.

In the sea-island structure fiber of the present invention, the flame retardant is added to the sea component to be extracted or decomposed and removed, so that after the generation of the ultrafine fiber bundle, the flame retardant is added to the voids inside the ultrafine fiber bundle. The presence of the flame retardant prevents the flame retardant from dropping off the sheet, and the dense elastic polymer foam (porous portion) present in the entangled space of the microfine fiber bundle acts as a filter, and the flame retardant falls off the sheet. Can be prevented. Furthermore, since the flame retardant expresses flame retardancy through the filter, most of the added flame retardant can work effectively. Therefore, in the present invention, it is also important that the fiber sheet contains the elastic polymer in a porous state. As a method for bringing the elastic polymer into a porous state, a wet coagulation method, that is, a method in which a solution of the elastic polymer is immersed in a coagulation bath in which the solvent is dissolved but the polymer is not dissolved to coagulate the polymer, or foaming is performed. And a method of heating the elastic polymer containing the agent to foam, or a method of heating and gelling the elastic polymer emulsion liquid.

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 such flame-retardant fine particles have thermal stability when melt-spinning ultrafine fiber-generating fibers and stability to polymers. Generally, the flame retardant containing a phosphorus-based or halogen-based compound as an active ingredient is nylon 6, nylon 66, nylon 6, which is an island component polymer of the present invention.
Polyamide polymer such as 10, polyethylene terephthalate, has a reactivity with polyester polymer such as polybutylene terephthalate and the like, polyethylene, polystyrene, polyethylene propylene copolymer and the like used for the sea component polymer of the present invention It is known that the reactivity with hydrocarbon-based polymers is low. Therefore, when the flame-retardant fine particles are kneaded into a sea component composed of a hydrocarbon-based polymer such as polyethylene, polystyrene, or polyethylene-propylene copolymer to melt-spin ultrafine fiber-generating fibers, nylon 6, nylon 66, nylon 610 are used. It is preferable that the contact time between the island component resin composed of a polyamide polymer such as a polyamide polymer such as polyethylene terephthalate and polybutylene terephthalate and the flame-retardant fine particles is shorter, and the island component and the sea component are compared with the mixed spinning. Is desirable, and a spinning method using a needle pipe type nozzle is desirable. Further, it is desirable that the flame-retardant fine particles do not undergo thermal decomposition at the temperature at which the sea-island type fiber is melt-spun. Desirably, there is no solubility or degradability with respect to the decomposing agent. The particle size of the flame-retardant fine particles is 2μ
If it exceeds m, the pack pressure will increase during melt spinning and the thread will break, which is not preferable. On the other hand, if it is less than 0.1 μm, the amount of water flowing out during removal of the sea component polymer increases, which is not preferable.

The ultrafine fiber-generating sea-island structure fiber is defibrated with a card, a web is formed through a webber, the obtained fiber web is laminated to a desired weight and thickness, and then a known method such as a needle is used. A nonwoven fabric is formed by performing an entanglement treatment by a punch method, a high-pressure water entanglement treatment method, or the like, or the staple is entangled with a woven fabric using a water flow or the like to form a fabric. When used for applications other than artificial leather, sea-island structural fibers can be used as spun yarn or as a multifilament yarn in the form of a fabric such as a knitted fabric. In addition, if necessary, a polyvinyl alcohol-based sizing agent is applied to the nonwoven fabric manufactured by the above method, or the surface of the constituent fibers is melted to bond the nonwoven fabric constituent fibers together, thereby temporarily fixing the nonwoven fabric. May be performed. By performing this treatment, it is possible to prevent the nonwoven fabric from being structurally destroyed by tension or the like in the subsequent step of impregnating the elastic polymer solution or the like.

Next, the cloth is impregnated with an elastic polymer liquid,
It is gelled by heating and drying, or is dipped in a liquid containing a non-solvent of the elastic polymer and wet-solidified to form a dense foamed sponge of the elastic polymer. Here, as the elastic polymer to be impregnated, for example, an average molecular weight of 500
At least one kind of polymer diol selected from diols such as polyester diols, polyether diols, polycarbonate diols and the like or complex diols such as polyester polyether diols;
At least one diisocyanate selected from aromatic, alicyclic, and aliphatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate; and 2 such as ethylene glycol and isophorone diamine. Polyurethanes obtained by reacting at least one low-molecular compound having at least one active hydrogen atom at a predetermined molar ratio, and modified products thereof. In addition, polyester elastomers, styrene-isoprene block copolymer Elastic polymers such as hydrogenated products and resins such as acrylic resins are also included. Further, a 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 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 and dry as it is. Then, a fiber sheet is obtained by a method of gelling to form a sponge. If necessary, additives such as a colorant, a coagulation regulator, an antioxidant, and a dispersant may be added to the polymer liquid. The ratio of the elastic polymer in the fiber sheet after the removal of the sea component is 10% or more, preferably 30 to 50% by weight as a solid content.
If the elastic body 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 ultrafine fibers.

Next, the fiber sheet containing the elastic polymer is treated with a chemical which is a non-solvent of the island component polymer and the elastic polymer and is a solvent of the sea component polymer or a decomposer to generate an ultrafine fiber bundle. Let it. In this step, the flame retardant kneaded into the sea component polymer is not removed in a considerable amount and remains in the fiber sheet in such a manner that it does not easily fall off. In the present invention, the fineness of the ultrafine fiber formed by removing the sea component from the sea-island structure fiber is 0.1
Denier or less is preferable because a luxurious suede-like nap is obtained. The amount of the flame retardant contained in the sheet (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 and 10% by weight or more based on the weight of the fiber sheet. Below, especially 0.3 wt% or more and 5 wt% or less are preferable from the viewpoint 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 flame retardant-containing liquid and drying the cloth is generally used. When the flame retardant is a fine particle in the bundle, the flame retardant hardly penetrates into the inside of the ultrafine fiber bundle, and most of the flame retardant exists on the outside of the fiber bundle or the outer surface of the sponge. In such a state, the flame retardant easily falls off, and a durable flame retardant effect cannot be obtained. In order to prevent the flame retardant from falling off, there is a method in which the flame retardant is kneaded into the binder resin and the cloth is impregnated with the binder resin liquid. The flame retardant is not covered, and the flame retardant is greatly reduced because the resin is covered with the resin. Further, since the resin is filled in the cloth, the flexibility of the cloth is impaired, and a good napped state cannot be obtained. However, in the case of the present invention, such a disadvantage does not occur.

The flame-retardant sheet of the present invention can obtain suede-like artificial leather by fluffing the surface thereof, and further melt or smooth the surface of the fiber sheet or apply resin to the surface. Further, artificial leather with a grain surface layer can be obtained by providing the surface with natural leather-like surface irregularities. From such artificial leather, shoes,
It can be used for not only miscellaneous goods such as bags and accessories, but also interior goods such as sofa upholstery and clothing. In particular, the fiber sheet of the present invention is suitable for applications requiring flame retardancy and applications requiring strength, such as automobile seats, railway vehicle seats, and interior goods.

[0020]

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-302 The tear strength of the sheet in the examples is A-1 of JIS L-1096 6.15.1.
(Single tongue method).

Examples 1-2 A low-density polyethylene master chip containing 6-nylon (island component), high-flow low-density polyethylene (sea component) and 20% of a phosphorus-based inorganic flame retardant [Daifunen PEMEH-9
06; Dainichi Seika Kogyo Co., Ltd., average particle size 0.5 μm] were mixed in the proportions shown in Table 1 to obtain sea-island type mixed spun fibers by melt spinning. After stretching by 5 times, applying a fiber oil agent, mechanically crimping and drying,
mm to form staples, forming a web with a basis weight of 600 g / cm ² by the cross lap method, and then needle punching about 500 P / cm ² alternately from both sides,
Further heating and pressing with a calender roll produced an entangled nonwoven fabric having a smooth surface. The basis weight of this entangled nonwoven fabric was 540 g / m ² , and the apparent specific gravity was 0.285. The entangled nonwoven fabric is impregnated with a dimethylformamide (DMF) solution of a polyurethane having a solid content of 20% mainly composed of a polytetramethylene ether-based polyurethane, and a DMF
After immersion in a water / water mixture and wet coagulation, the sea component in the mixed spun fiber is eluted and removed in hot toluene to express ultrafine fibers, which has a 1.30 mm thick tear strength and flame retardancy. A fibrous sheet substrate 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. Average denier of microfibers (determined by dividing the total cross-sectional area of microfibers present in one fiber bundle in the cross section of the fiber bundle by the number of microfibers present in the cross section)
Was 0.006 denier. The weight ratio of fiber to polyurethane in the fiber sheet was about 5: 2. When the cross section of the fiber 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 inside of the ultrafine fiber bundle and the inside surface of the porous elastic polymer. Table 2 shows the results of evaluating the tear strength and flame retardancy of each of the obtained sheets.

Examples 3 and 4 6-nylon (island component) as island component, high-flow low-density polyethylene (sea component) as sea component and phosphorus-based inorganic flame retardant 2
Using a low-density polyethylene master chip containing 0% [Daifunen PEM EH-906; manufactured by Dainichi Seika Kogyo Co., Ltd., average particle size: 0.5 μm] in the ratio shown in Table 1, and using a lamination type nozzle, 50 island cores A sheath fiber was prepared. Using this fiber, a fibrous sheet substrate was obtained in the same manner as in 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. 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. The average denier of the ultrafine fibers was 0.05 denier. Table 2 shows the results of evaluating the tear strength and flame retardancy of each of the obtained sheets.

Examples 5 to 6 6-nylon (island component) for island component, high-flow low-density polyethylene (sea component) for sea component and inorganic phosphorus-based flame retardant 2
Using a low-density polyethylene master chip containing 0% [Daifunen PEM EH-906; manufactured by Dainichi Seika Kogyo Co., Ltd., average particle size 0.5 μm] in the ratio shown in Table 1, and using a needle pipe type nozzle, 50 island cores A sheath fiber was produced. Using this fiber, a fibrous sheet substrate was obtained in the same manner as in Examples 1 and 2. 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. The average denier of the ultrafine fibers is 0.
It was 05 denier. Table 2 shows the results of evaluating the tear strength and flame retardancy of each of the obtained sheets.

Comparative Example 1 A fibrous sheet substrate 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 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 a flame retardant master chip for the island component, and high fluidity polyethylene for the sea component at the ratio shown in Table 1, 50 island core-sheath type fibers were produced using a needle pipe type nozzle. Using these fibers, a fibrous sheet substrate having a thickness of 1.30 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 obtained sheet is
Although it had flame retardancy, it had low tear strength. When the presence state of the flame retardant was observed in the same manner as in Example 1 above, it was found on the surface of the ultrafine fibers, but hardly found in the voids in the ultrafine fiber bundle. 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 as the island component and a high-fluidity polyethylene as the sea component at the ratio shown in Table 1, a 50-core core-sheath fiber was produced using a lamination type nozzle. did. 1.30 mm thick under the conditions of Examples 1-2 using this fiber
Was prepared. 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 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 above, it was found on the surface of the ultrafine fibers, but hardly found in the voids in the ultrafine fiber bundle. Table 2 shows the results of evaluating the tear strength and flame retardancy.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

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, particularly suede-like artificial leather, and is suitable for applications requiring strength and flame retardancy such as automobile seats, railway car seats, and sofa lining materials. ing. Further, the sheet of the present invention can be used for general uses other than artificial leather.

Claims (5)

[Claims] 1. A fabric comprising a microfine fiber bundle and a fiber sheet comprising a porous elastic polymer present in the cloth, wherein a flame retardant is present in a void inside the microfine fiber bundle and a void inside the porous elastic polymer. Flame retardant sheet characterized by being present. 2. The flame-retardant 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 a fiber sheet comprising a porous elastic polymer contained in the fabric, and a sea component of the fibers. A method for producing a fiber sheet comprising an ultrafine fiber bundle and an elastic polymer by removing a polymer, wherein a fiber in which a flame retardant is added to a sea component polymer is used as the sea-island structure fiber. Method for producing a functional sheet. 4. The production method according to claim 3, wherein the fiber cross section of the sea-island structural fiber has a structure in which the sea component polymer is divided into a plurality by the island component polymer. 5. The method according to claim 3, wherein the flame retardant is a flame-retardant fine particle having a particle diameter of 1 μm or less.