Piled sheet and process for producing the same

Abstract

A raised sheet composed of three layers which are united by entanglement. The three layers are united in a layered structure of entangled nonwoven fabric A made of microfine fibers / polyurethane sheet B / woven or knitted fabric C or a layered structure of entangled nonwoven fabric A made of microfine fibers / woven or knitted fabric C / polyurethane sheet B. On the surface of the entangled nonwoven fabric A, raised naps of the microfine fibers are formed. A part of the microfine fibers constituting the entangled nonwoven fabric A penetrates through the polyurethane sheet B and the woven or knitted fabric C in this order, or penetrates through the woven or knitted fabric C and the polyurethane sheet B in this order. At least a part of the penetrated microfine fibers bonds to polyurethane which constitutes the polyurethane sheet B. The raised sheet is excellent in the shape stability, for example, it does not lose its shape even after a long term use. In addition, the raised sheet has a good surface abrasion resistance and a soft and high-quality hand.

Description

TECHNICAL FIELD[0001]The present invention relates to a raised sheet with little loss of shape even after a long term use having a good surface abrasion resistance and a soft hand, which is suitably used as the covering fabric for vehicle seats and interior furniture such as cushion sheet, sofa and chair.BACKGROUND ART[0002]Artificial leathers have been used in various applications such as interior, clothes, shoes, bags, gloves, and covering fabrics for vehicle seats. Particularly in the field of the covering fabric for vehicle seats such as railroad vehicle seat, automotive seat, airplane seat and ship seat and the covering fabric for interior furniture such as cushion sheet and sofa and chair, artificial leathers which combine a good surface abrasion resistance and a high shape stability resistant to elongation, loss of elasticity and wrinkling even after a long term use have been keenly required.[0003]Recently, artificial leathers having a substrate made of a nonwoven fabric, par...

AI Technical Summary

Benefits of technology

[0010]The polymer for microfine fibers is at least one kind of polymer sparingly soluble in water which is selected from melt-spinnable polyamides such as 6-nylon, 66-nylon and 12-nylon, and melt-spinnable polyesters such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate and their copolymers. The component to be removed by extraction or decomposition of the extraction-type composite fibers is a water-soluble polymer which is different from the microfine fiber-forming component in the solubility and decomposability, which is less compatible with the microfine fiber-forming component, and which has a melt viscosity or surface tension smaller than those of the microfine fiber-forming component under the spinning conditions. Talking the prevention of environmental pollution and the shrinking properties upon dissolution into consideration, a heat-melting, hot water-soluble polyvinyl alcohol is preferably used as the component to be removed by extraction or decomposition. The microfine fibers may be spinning-colored with an inorganic pigment such as carbon black and titanium oxide or an organic pigment or may be added with a known additive for fibers, in an extent not adversely affecting the effect of the invention.

[0011]The heat-melting, hot water soluble polyvinyl alcohol (PVA) is produced by saponifying a resin mainly constituted by vinyl ester units. Examples of vinyl monomers for the vinyl ester units include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate and vinyl versatate, with vinyl acetate being preferred in view of easiness of production of PVA.

[0012]PVA may be homo PVA or modified PVA introduced with co-monomer units, with the modified PVA being preferred in view of a good melt spinnability, water solubility and fiber properties. In view of a good copolymerizability; melt spinnability and water solubility, preferred examples of the co-monomers are α-olefins having 4 or less carbon atoms such as ethylene, propylene, 1-butene and isobutene; and vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether and n-butyl vinyl ether. The content of the comonomer units in PVA is preferably 1 to 20 mol %, more preferably 4 to 15 mol %, and still more preferably 6 to 13 mol % base on the total constitutional units in the modified PVA. Particularly preferred is ethylene-modified PVA, because the fiber properties are enhanced when the comonomer unit is ethylene. The content of the ethylene units is preferably 4 to 15 mol % and more preferably 6 to 13 mol %.

[0013]PVA can be produced by a known method such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. Generally, a bulk polymerization or solution polymerization in the absence or presence of a solvent such as alcohol is employed. Examples of the solution for the solution polymerization include lower alcohols such as methyl alcohol, ethyl alcohol and propyl alcohol. The copolymerization is performed in the presence of a known initiator, for example, an azo initiator or peroxide initiator such as a,a′-azobisisobutyronitrile, 2,2′-azobis(2,4-dimethyl-varelonitrile), benzoyl peroxide, and n-propyl peroxycarbonate. The polymerization temperature is not critical and 0 to 150° C. is recommended.

[0014]The viscosity average polymerization degree of PVA is preferably 200 to 500, more preferably 230 to 470, and still more preferably 250 to 450. The polymerization degree (P) is measured according to JIS-KG726, in which a PVA-based resin is re-saponified and purified, and then, an intrinsic viscosity [η] is measured in water at 30° C. The polymerization degree (P) is calculated from the following equation:P=([η]103 / 8.29)(1 / 0.62).

[0015]The saporfication degree of the PVA is preferably 90 to 99.99 mol %, more preferably 93 to 99.98 mol %, still more preferably 94 to 99.97 mol %, and particularly preferably 96 to 99.96 mol %. The melting point of PVA (Tm) is preferably 160 to 230° C., more preferably 170 to 227° C., still more preferably 175 to 224° C., and particularly preferably 180 to 220° C. Using DSC (TA3000 manufactured by Mettler Co. Ltd.), the sample was heated to 300° C. at a temperature rising rate of 10° C. / min in nitrogen atmosphere, cooled to room temperature, and then, heated again to 300° C. at a temperature rising rate of 10° C. / min. The peak top temperature of the obtained endothermic curve is taken as the melting point.

Problems solved by technology

However, the artificial leathers having a substrate which is made only of a nonwoven fabric of microfine fibers have a problem of easy deformation.

For example, a covering fabric of chair is likely strained by person's weight which is loaded thereon repeatedly for a long period of time.

However, although the deformation is effectively prevented, the hand becomes hard and the sewing is difficult because of wrinkling in case of complicated design.

However, the entangled body having only a woven or knitted fabric united is poor in the recovery from elongation and causes strain on the portion repeatedly subjected to person's weight after use for several years.

In addition, the surface abrasion resistance cannot be improved only by laminating a woven or knitted fabric.

However, if used in an application, such as a covering fabric for chair, which is repeatedly subjected to person's weight for a long period of time, the proposed sheet is easily permanently stretched and does not fit for practical use because of the lack of structure for preventing excessive elongation which is possessed by a woven fabric.

Therefore, the sheets hitherto proposed are not sufficient in the shape stability and surface abrasion resistance during a long term use.