JP2006299485A - Napped flame-retardant leather-like sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flame-retardant leather-like sheet which is free from the spreading of fire due to the dropping of a melted polymer, when burnt, and has both a self-extinguishing property and carbonization type flame retardance. <P>SOLUTION: This flame-retardant leather-like sheet is characterized by comprising a cellulosic fiber nonwoven fabric which has naps having an average single fiber fineness of ≤1.0 dtex on at least one side and to which a polymer elastomer and a flame retardant are imparted. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flame retardant leather-like sheet comprising a nonwoven fabric comprising cellulose-based fibers, and relates to an excellent carbonization-type flame retardant leather-like sheet that does not burn and spread due to the fall of molten polymer during combustion. Is.

  Artificial leather made of ultrafine synthetic fibers has excellent surface quality, texture, and various fastnesses, and has expanded to the market for clothing, furniture, and vehicle seats. However, it is flame retardant due to the low self-extinguishing properties unique to synthetic fibers. There was a limit to entering into applications where demanded. This is due to the combustion mechanism of synthetic fibers. Mainly used polyesters and polyamides are those in which a combustible gas generated by decomposition of a polymer by heating is burnt as a fuel, and the polymer melts at a high temperature to cause droplets to drop.

  At present, drip-type flame retardant, which stops combustion by separating the molten polymer from the combustion system, is the mainstream technology for flame retarding synthetic fibers, but the molten polymer that falls is the source of ignition and burns to the surroundings. Spreading is a problem.

  Up to now, a method of obtaining flame retardancy by applying a halogen-based flame retardant mainly composed of an antimony compound, bromine or chlorine has been used for flame retarding of artificial leather made of polyester or polyamide. As a flame retardant processing technique for suede-like artificial leather, a method of back coating a flame retardant has been proposed (see, for example, Patent Document 1). This method was developed mainly for applications such as vehicle seats, but the texture of the product is reduced, and the flame retardant mechanism is a drip type due to the fall of the molten polymer, which may spread to the surroundings. There was a problem. In addition, antimony compounds are toxic in themselves, and halogen-based flame retardants are likely to be dioxin-generated at the time of incineration, so that their use is limited.

  From such environmental considerations, it has been proposed to use phosphorus-based or silicone-based flame retardants as substitutes for halogen-based flame retardants (see, for example, Patent Document 2). However, these flame retardants are not only inferior in flame retardant effect compared to halogen flame retardants, but still have a problem of burning off due to dropping of the molten polymer. Further, it is known that the carbonized flame retardancy can be obtained by increasing the amount of the flame retardant attached to about 40%, but there is a problem that the texture becomes extremely stiff.

  A method of mixing a flame retardant with polyurethane has also been proposed (see, for example, Patent Document 3). However, when this method is used, the physical properties such as the strength of polyurethane as a resin are reduced, so not only a vehicle seat that requires strict weather resistance performance can withstand the demand, but also the burning and spreading due to the dropping of the molten polymer. Is still not resolved.

Therefore, in synthetic leather applications, when using a synthetic fiber such as polyester or polyamide as a fiber type, and a polymer elastic body as a binder, both the fiber and the binder melt at the time of combustion, so it is difficult to suppress the spread of the flame due to the fall of the molten polymer, It has been considered extremely difficult to obtain a self-extinguishing property that does not drip and further extinguishes fire.
JP-A-5-302273 JP 2002-38374 A Japanese Patent Laid-Open No. 7-18484

  In view of the actual state of the prior art, the object of the present invention is to have carbonization using cellulosic fibers as constituent fibers of a leather-like sheet, and further to maintain self-extinguishing properties by adding a flame retardant, An object of the present invention is to provide a flame-retardant leather-like sheet that has both self-extinguishing properties and carbonization-type flame retardance that do not cause molten polymer to drop during combustion.

  The leather-like sheet of the present invention has the following configuration in order to solve the above problems.

  (1) A flame retardant leather-like sheet comprising a cellulose fiber nonwoven fabric having napped fibers having an average single fiber fineness of 1.0 dtex or less on at least one surface and provided with a polymer elastic body and a flame retardant.

  (2) The flame-retardant leather-like sheet according to (1), wherein the cellulosic fiber is a regenerated cellulosic fiber.

  (3) The flame-retardant leather-like sheet according to (2), wherein the regenerated cellulosic fiber is lyocell.

  (4) The flame retardant leather according to any one of (1) to (3), wherein the flame retardant is selected from halogen, organic / inorganic phosphorus, and silicone. Like sheet.

  (5) The flame-retardant leather-like sheet according to any one of (1) to (4), wherein napped fibers are made of short fibers.

  According to the present invention, in a conventional artificial leather characterized by a drip-type flame retardant that causes a molten polymer to fall during combustion, by using a cellulosic fiber as the fiber type, the carbonization type flame that does not spread and spread by the molten polymer falls. A flame-retardant leather-like sheet that exhibits flame retardancy can be provided. Further, the leather-like sheet of the present invention can be used for applications such as interior goods such as sofa upholstery materials, clothing, as well as miscellaneous goods such as shoes, bags, and accessories. It is especially excellent as a base layer for artificial leather with suede and silver tone, and it is required to be flame retardant for vehicle seats such as automobile seats, railcar seats, aircraft seats, and ship seats. Suitable for use. Moreover, it can be used for general uses other than those in which artificial leather is usually used, such as wallpaper, curtains, carpets and the like.

  Hereinafter, the present invention will be described in more detail.

  The nonwoven fabric used in the present invention has napped fibers having an average single fiber fineness of 1.0 dtex or less on at least one side. Here, it is preferable that 50% or more of fibers having an average single fiber fineness of 1.0 dtex or less constituting the nonwoven fabric is contained with respect to the weight of the leather-like sheet. When fibers having an average single fiber fineness of greater than 1.0 dtex are contained in an amount of 50% or more, high-quality surface quality and feel unique to artificial leather can be obtained because the rigidity of the fibers is large and the fluffiness is high. It is not preferable because it cannot be done. In addition, when 50% or more of fibers having an average single fiber fineness of less than 0.001 dtex are included, the abrasion resistance is poor, which is not preferable. The average single fiber fineness is preferably 0.005 to 0.8 dtex. The single fiber average fineness referred to here is a scanning electron microscope (SEM) photograph of the sheet surface taken at a magnification of 2000 times, randomly selecting 100 circular or nearly elliptical fibers, and determining the fiber diameter. The average value was measured and the fineness was calculated, which was defined as the single fiber average fineness.

  In order to obtain carbonization-type flame retardancy, it is important to use cellulosic fibers as the fibers constituting the nonwoven fabric. Cellulosic fibers are not particularly limited, but regenerated cellulosic fibers are preferred. For example, viscose rayon, copper ammonia rayon, solvent-spun rayon fiber (lyocell) and the like can be used, but lyocell is preferred from the viewpoint of easy ultrafineness by fibrillation and environmental load in production. In addition, the nonwoven fabric used for this invention may be what kind of structure, as long as it forms the napping of the fiber whose single fiber average fineness is 1.0 dtex or less on at least one side. For example, the nonwoven fabric which consists of a single cellulosic fiber may be sufficient, and the cellulosic fiber layer which forms the surface, and another cellulosic fiber layer may be laminated | stacked. In addition, a woven or knitted fabric that is three-dimensionally entangled with a non-woven fabric whose entire surface is covered with a fiber layer on the surface may be arranged.

  Moreover, it is preferable that the napping in the fiber layer on the surface is made of short fibers having a fiber length of 1 to 500 mm from the viewpoint that the non-woven fabric in the present invention becomes uniform.

  In the leather-like sheet of the present invention, a polymer elastic body is imparted to the nonwoven fabric in order to strengthen the entanglement between the fibers and obtain a texture as a leather-like sheet. As such a polymer elastic body, polyurethane-based, acrylic-based, polyester-based, polyamide-based, polyolefin-based elastomer resins and the like can be used. Among them, polyurethane is preferable from the viewpoint of texture.

  In the leather-like sheet of the present invention, the strong stability and cushioning properties that are manifested by the inclusion of the polymer elastic body are important in terms of the texture of the sheet. The content of the polymer elastic body is preferably 5 to 50% by weight with respect to the weight of the fibers constituting the whole nonwoven fabric, and the texture of the sheet can be adjusted by the content. When the amount is less than 5% by weight, the fiber is often dropped and the durability is inferior. If it exceeds 50% by weight, the processability and productivity are inferior, the polymer elastic body is easily exposed on the surface of the sheet, and the sheet rigidity is increased.

In the leather-like sheet of the present invention, the basis weight of the sheet is preferably 40 to 400 g / m ² . When the basis weight is less than 40 g / m ² , the sheet is inferior in strength, abrasion resistance and texture, which is not preferable. Moreover, when it exceeds 400 g / m < ² >, since workability and productivity are inferior and satisfactory texture cannot be obtained, it is not preferable.

  In the present invention, the nonwoven fabric is provided with a flame retardant. As the flame retardant, any of antimony, halide, organic / inorganic phosphorus, silicone, and the like may be used. System, organic / inorganic phosphorous, and silicone are preferred. The flame retardant may be present on either the sheet surface or the sheet inner surface, and may be contained and exhausted in the polymer elastic body or in the cellulosic fiber.

Next, an example of the method for producing the leather-like sheet of the present invention will be described. The leather-like sheet of the present invention can be produced by combining, for example, the following steps.
A step of producing a regenerated cellulose fiber having an ultrafine fiber generation of 1.0 dtex or less, a step of forming an entangled nonwoven fabric from the cellulose fiber, a step of impregnating the nonwoven fabric with a polymer elastic body and solidifying the polymer elastic body These are a step of modifying the fiber into an ultrafine fiber bundle, a step of forming napped on at least one side, a step of directly dyeing the napped-toned fiber sheet with a dye, and a step of adding a flame retardant to the dyed sheet.

  Extra fine fibers are obtained by spinning directly by ordinary wet, dry and melt spinning methods, and also by melt blown method, sea island type fiber and polymer blend fiber by eluting and removing one component, and split fiber method. Although a thing can be used, the method of making it ultrafine by the fibrillation by surface friction is preferable from a viewpoint of an environmental surface and an operation surface.

  The entangled nonwoven fabric is produced from the above-mentioned various ultrafine fibers by a dry method such as card, cross layer, random webber, etc., and a wet papermaking method in which ultrafine fibers are dispersed in water. It is obtained by entanglement and integration.

  As a method for applying the polymer elastic body, a method in which the polymer elastic body is impregnated into a nonwoven fabric as an aqueous emulsion or an organic solvent solution and then solidified, a coating method using knife coating, gravure coating, or the like is used. Among these, from the viewpoint of processability, a method of solidifying after impregnating a polymer elastic body solution into a non-woven sheet is preferably used.

  Examples of the flame retardant coating method include impregnating a dried product after dyeing with a diluted solution of various flame retardants, squeezing at a pickup rate of 50 to 100%, and drying and finishing at a temperature of 80 to 120 ° C. The back surface of the sheet is coated with a doctor knife or a gravure coating method and dried at 80 to 120 ° C. to finish.

  The flame-retardant leather-like sheet-like material of the present invention provides a suede-like artificial leather by raising the surface thereof, and further melts and smoothes the surface of the fiber sheet, or applies a resin to the surface, It is also possible to make an artificial leather with silver by imparting surface irregularities like natural leather to the surface.

  From such artificial leather, it can be used for miscellaneous goods such as shoes, bags, accessory cases, interior goods such as sofa upholstery materials, and clothing. In particular, the flame retardant of the present invention is used in applications requiring flame retardancy such as vehicle seats such as automobile seats, railway vehicle seats, airplane seats, and ship seats that require severe flame retardancy. Sexual leather-like sheets are suitable.

EXAMPLES Hereinafter, although this invention is demonstrated further more concretely using an Example, this invention is not limited to a following example. Moreover, the evaluation methods and measurement conditions used in Examples and Comparative Examples will be described below.
(1) Flame retardancy: FMVSS-302
When this test method has self-extinguishing properties, the flame retardancy was set.
(2) Drip property:
In the flame retardancy test of the above item (1), a carbonized flame retardant level was defined as one in which the molten polymer did not fall.
(3) Single fiber average fineness:
A scanning electron microscope (SEM) photograph of the surface of the sheet was taken at a magnification of 2000 times, 100 fibers having a circular shape or a nearly elliptical shape were randomly selected, the fiber diameter was measured, the average value was calculated, and the fineness was calculated. It was defined as the average single fiber fineness.
(4) Weight per unit:
The weight of the sheet 1.0 m ² was measured and calculated.

Example 1
Non-fibrillated lyocell short fibers (1.7 dtex × 4 mm, manufactured by Coatles Co., Ltd.) were dispersed in water, adjusted to a dry weight of 120 g / m ^2, and paper was made using a standard square hand paper machine. Then, it dried with the cylinder dryer, the base material was created, and the sheet | seat of thickness 0.50mm and 120 g / m < ² > of fabric weight was obtained.

  This lyocell short fiber nonwoven fabric is fibrillated on the surface by water jet treatment and then dried to give 20% by weight of polycarbonate polyurethane (manufactured by Sanyo Kasei) to the fiber weight. Polyurethane was coagulated and dried, and raised with a 240 mesh sandpaper to produce a nonwoven sheet with a single fiber average fineness of 0.5 dtex.

The obtained sheet was put into a circular dyeing machine, and was directly dyed and browned using a dye. In contrast to this dyeing solution, a solution containing 10% of an organophosphorus flame retardant containing guanidine phosphate as a main component is impregnated. Dried. As a result, a sheet having a thickness of 0.50 mm, a basis weight of 140 g / m ² , and a flame retardant weight of 10% by weight was obtained.

  As a result of evaluating the combustibility of the obtained sheet with FMVSS-302, a result of carbonization-type flame retardancy that is self-extinguishing and that does not drop the molten polymer was obtained. Table 1 shows the results.

Example 2
The pulp and N-morpholine-N-oxide aqueous solution were put into a mixing tank and mixed under reduced pressure to prepare a cellulose spinning stock solution having a cellulose concentration of 10%. The obtained cellulose stock solution was subjected to air gap spinning at a discharge temperature of 125 ° C. The spinning dope was discharged at a rate of 0.2 g / min per spinning hole, and was continuously collected on a net conveyor below 50 cm. The net conveyor was moved at a speed of 2.5 m / min and was swung at a speed of 50 times / min using a rocking device in a direction orthogonal to the traveling direction.

Subsequently, scouring and washing with water are performed, and the fibers on the surface are fibrillated by water jet treatment, followed by drying, and a lyocell fiber web having a basis weight of 80 g / m ² made of lyocell long fibers having an average single fiber fineness of 0.7 dtex. Obtained.

Polyurethane is applied to the obtained lyocell fiber web in the same manner as in Example 1, the surface is subjected to raising treatment, an organic phosphorus flame retardant is applied, thickness is 0.45 mm, basis weight is 100 g / m ² , and flame retardant is attached. A sheet with an amount of 10% by weight was obtained.

  As a result of evaluating the combustibility of the obtained sheet with FMVSS-302, a result of carbonization-type flame retardancy that is self-extinguishing and that does not drop the molten polymer was obtained. Table 1 shows the results.

Example 3
A non-woven sheet was produced in the same design as in Example 1, and a flame retardant mixed with a halide and an antimony compound was applied instead of the organophosphorus flame retardant of Example 1, and the thickness was 0.50 mm and the basis weight was 140 g / m. ^2. A sheet with a flame retardant content of 20% by weight was obtained.

  As a result of evaluating the combustibility of the obtained sheet with FMVSS-302, a result of carbonization-type flame retardancy that is self-extinguishing and that does not drop the molten polymer was obtained. Table 1 shows the results.

Comparative Example 1
Island component is polyethylene terephthalate, sea component is polystyrene, island / sea ratio = 80/20% by weight, island number is 16 islands, average fineness of composite fiber is 4dtex, average cut length is 51mm, average Ken shrinkage number is 12 mountains / in Using short fibers of molecular inter-array fibers, the short fibers were made into a web with a card cross wrapper, and needle punched to produce a felt having a basis weight of 520 g / m ² . The felt was subjected to shrinkage treatment, dried, provided with polyvinyl alcohol, dried, dipped in trichlene, and squeezed with mangles, and then dried. This sheet is impregnated with polyester-polyether-based polyurethane as solids to 30 parts per island fiber, wet coagulated, solvent removed, dried, and a polyethylene terephthalate ultrafine fiber bundle having a single fiber average fineness of 0.2 dtex A sheet in which a polymer elastic body was applied to the entangled body was obtained. This sheet was cut in half, and the non-half cut surface was brushed with 240 mesh sandpaper to produce a living machine.

Next, this raw machine was put into a circular dyeing machine and dyed to brown using a disperse dye and finished. In contrast to this dyeing solution, a solution containing 20% of an organic phosphorus flame retardant mainly composed of guanidine phosphate is impregnated, squeezed with a mangle roller at a squeezing rate of 100%, and heated with a hot air dryer set at 100 ° C. for 10 minutes Dried. As a result, a sheet having a basis weight of 540 g / m ² and a flame retardant application amount of 10% by weight was obtained.

  As a result of evaluating the combustibility of the obtained sheet with FMVSS-302, it was combustible, and further, the fall of the molten polymer was observed. Table 1 shows the results.

Comparative Example 2
A nonwoven fabric sheet was produced with the same design as in Example 1, and a sheet having a thickness of 0.50 mm and a basis weight of 140 g / m ² was obtained by not applying a flame retardant.

  As a result of evaluating the combustibility of the obtained sheet with FMVSS-302, it was combustible. Table 1 shows the results.

Claims (5)

A flame-retardant leather-like sheet comprising a cellulose fiber nonwoven fabric having napped fibers having an average single fiber fineness of 1.0 dtex or less on at least one surface and provided with a polymer elastic body and a flame retardant. The flame-retardant leather-like sheet according to claim 1, wherein the cellulosic fiber is a regenerated cellulosic fiber. The flame retardant leather-like sheet according to claim 2, wherein the regenerated cellulosic fiber is lyocell. The flame retardant leather-like sheet according to any one of claims 1 to 3, wherein the flame retardant is selected from halogen, organic / inorganic phosphorus, and silicone. 5. A flame-retardant leather-like sheet according to any one of claims 1 to 4, wherein napped fibers are made of short fibers.