METHOD FOR THERMOFORMING PRODUCT OF FILAMENTS

Abstract

To provide a thermoforming method for obtaining a thermoformed article that exhibits excellent abrasion resistance at melt-bonded portions, and excellent adhesive strength between woven fabrics or to another kind of article. Polyethylene having a melt flow rate, measured under conditions of a temperature of 280 C. and a load of 2.16 kg, of 10 to 15 g/10 min and polyethylene terephthalate are prepared. By a conjugate melt spinning method using the polyethylene terephthalate as a core component and the polyethylene as a sheath component, multi-filament yarn in which core-sheath composite filaments having a core component:sheath component mass ratio of 1 to 4:1 are bundled is obtained. A product of filaments is obtained by weaving, knitting, braiding or winding using the multi-filament yarn. Thermoforming of the product of filaments is carried out by heating the product of filaments to melt the polyethylene, thereby melt-bonding the core-sheath composite filaments to each other, with the polyethylene terephthalate retaining its initial filament form.

Claims

1. A method for thermoforming a product of filaments, comprising: a step of bundling a plurality of core-sheath type composite filaments to obtain a multi-filament yarn, wherein the core-sheath type composite filament is composed of a sheath component formed from a polyethylene having a melt flow rate, measured under conditions of a temperature of 280 C. and a load of 2.16 kg, of 10 to 15 g/10 min, and a core component formed from polyethylene terephthalate, which is obtained by a conjugate melt spinning method and has a core component:sheath component mass ratio of 1 to 4:1, a step of using the multi-filament yarn to prepare a product of filaments, and a step of heating the product of filaments to melt the polyethylene, thereby melt-bonding the core-sheath composite filaments to each other, with the polyethylene terephthalate retaining its initial filament form.

2. The method for thermoforming a product of filaments according to claim 1, wherein the product of filaments is selected from the group consisting of a knitted or woven fabric, a net fabric and a string.

3. The method for thermoforming a product of filaments according to claim 1, wherein after the products are laminated to each other, the polyethylene is melted with the polyethylene terephthalate retaining its initial filament form, and the core-sheath composite filaments existing in the products are melt-bonded to each other, simultaneously the products are integrated to each other.

4. The method for thermoforming a product of filaments according to claim 1, wherein after the product and another kind of article are laminated to each other, the polyethylene is melted with the polyethylene terephthalate retaining its initial filament form, and the core-sheath composite filaments existing in the product are melt-bonded to each other, simultaneously the product and the other kind of article are integrated to each other.

5. The multi-filament yarn used in the method according to claim 1, characterized in that the multi-filament yarn is formed by bundling a plurality of the core-sheath composite filaments, wherein the core-sheath type composite filament is composed of a sheath component formed from a polyethylene having a melt flow rate, measured under conditions of a temperature of 280 C. and a load of 2.16 kg, of 10 to 15 g/10 min, and a core component formed from polyethylene terephthalate, which has a core component:sheath component mass ratio of 1 to 4:1,

6. The multi-filament yarn according to claim 5, wherein the sheath component comprises magnesium stearate.

Description

EXAMPLES

Example 1

Preparation of Multi-Filament Yarn

[0014] As a sheath component, polyethylene (manufactured by Japan Polyethylene Corporation, product number UJ960) having a melting point of 126 C. and a melt flow rate of 13.2 g/10 min was prepared. As a core component, polyethylene terephthalate having a melting point of 256 C. was prepared.

[0015] The polyethylene and the polyethylene terephthalate were fed to a conjugate melt spinning apparatus equipped with a core-sheath conjugate spinneret having 192 holes with a hole diameter of 0.6 mm at a spinneret temperature of 280 C. and a polyethylene:polyethylene terephthalate of 1:3 (mass ratio) to perform conjugate melt spinning. The obtained yarn in which 192 core-sheath composite filaments were bundled was subjected to cooling, stretching and relaxation treatments by conventional means to prepare multi-filament yarn having 1670 dtex/192 filaments.

Preparation and thermoforming of product of filaments (Part 1)

[0016] The obtained multi-filament yarn was twisted with a twist number of 60 T/m, and used as warp and weft to prepare a plain-woven fabric having a warp density and a weft density of 20 yarns/inch by weaving. Two pieces of the plain-woven fabric cut into a width of 40 mm and a length of 260 mm were laminated and placed in a mold, and thermoformed under conditions of a temperature of 150 C., a time period of 5 minutes and a pressure 0.5 MPa, and a thermoformed article A was obtained having a melt-bonded portion with a width of 20 mm and a length of 200 mm formed in the central portion. The thermoformed article A had two plain-woven fabrics firmly adhered to each other, in which in the central portion, the sheath components of the core-sheath composite filaments in the respective plain-woven fabrics were melt-bonded to each other.

Preparation and Thermoforming of Product of Filaments (Part 2)

[0017] The obtained multi-filament yarn was twisted with a twist number of 60 T/m and introduced into an 8-square braiding machine to prepare an 8-yarn braid. Then, under conditions of a temperature of 150 C. and a time period of 10 minutes, the sheath components of the core-sheath composite filaments in the braid were melt-bonded to each other to prepare a thermoformed article B which was integrated as a whole. This thermoformed article B had excellent abrasion resistance.

Example 2

[0018] Multi-filament yarn was obtained in the same manner as in Example 1 except that as the sheath component, polyethylene (manufactured by Prime Polymer Co., Ltd., product number SP4030) having a melting point of 127 C. and a melt flow rate of 14.5 g/10 min was used. Using the multi-filament yarn, thermoformed articles A and B were prepared by performing Preparation and thermoforming of product of filaments (Part 1) and (Part 2) in the same manner as in Example 1.

Comparative Example 1

[0019] Multi-filament yarn was obtained in the same manner as in Example 1, except that as the sheath component, polyethylene (manufactured by Japan Polyethylene Corporation, product number HJ490) having a melting point of 133 C. and a melt flow rate of 65.3 g/10 min was used. Using the multi-filament yarn, thermoformed articles A and B were prepared by performing Preparation and thermoforming of product of filaments (Part 1) and (Part 2) in the same manner as in Example 1.

Comparative Example 2

[0020] Multi-filament yarn was obtained in the same manner as in Example 1, except that as the sheath component, polyethylene (manufactured by Japan Polyethylene Corporation, product number UJ560) having a melting point of 123 C. and a melt flow rate of 59.8 g/10 min was used. Using the multi-filament yarn, thermoformed articles A and B were prepared by performing Preparation and thermoforming of product of filaments (Part 1) and (Part 2) in the same manner as in Example 1.

[0021] For the thermoformed articles A obtained in Examples 1 and 2 and Comparative Examples 1 and 2, using Autograph AG50kNI manufactured by Shimadzu Corporation, parts of the plain-woven fabrics not bonded to each other at one end along the width of the thermoformed article A were hold with a chuck, and a peeling test was performed at a pulling speed of 100 mm/min to measure the peeling strength. The peeling test was performed on three thermoformed articles A, and the peeling strength was defined as the average value among the respective values at which the load had the maximum value during the test. As a result, the peeling strength was 17.8 N for the thermoformed article A according to Example 1, 15.7 N for the one according to Example 2, 10.1 N for the one according to Comparative Example 1, and 13.1 N for the one according to Comparative Example 2. From these, it can be seen that the thermoformed articles A according to Examples 1 and 2 are excellent in adhesive strength between two plain-woven fabrics.

[0022] For the thermoformed articles B obtained in Examples 1 and 2 and Comparative Examples 1 and 2, using a abrasion resistance tester manufactured by Yonekura MFG Co., Ltd., the abrasion resistance was evaluated. Specifically, a 180 g weight was hung on one end of the thermoformed article B, and the other end was gripped by a chuck such that the thermoformed article B came into contact with a hexagonal rod at a right angle. Then, the other end was reciprocated. The number of reciprocating motions was 301 times/min, and the stroke width was 230 mm30 mm. As a result, the fluffing on the surface of the thermoformed articles B according to Comparative Examples 1 and 2 was more remarkable than that of the thermoformed articles B according to Examples 1 and 2. In addition, replacing the 180 g weight with a 1 kg weight and performing the abrasion resistance test for about 20 minutes, the thermoformed articles B according to Examples 1 and 2 did not break, whereas the thermoformed article B according to Comparative Example 1 broke in about 15 minutes. Furthermore, the thermoformed article B according to Comparative Example 2 did not break, but the melt-bonding of the thermoformed article B was released, and the multi-filament yarn was exposed and became fibrous. From these, it can be seen that the thermoformed articles B according to Examples 1 and 2 are excellent in abrasion resistance.

Example 3

Preparation of Multi-Filament Yarn

[0023] As the sheath component, a polyethylene composition was prepared by adding 0.05% by weight magnesium stearate to polyethylene (manufactured by Japan Polyethylene Corporation, product number UJ960) having a melting point of 126 C. and a melt flow rate of 13.2 g/10 min. On the other hand, as a core component, polyethylene terephthalate having a melting point of 256 C. was prepared.

[0024] The polyethylene composition and the polyethylene terephthalate were fed to a conjugate melt spinning apparatus equipped with a core-sheath conjugate spinneret having 128 holes with a hole diameter of 0.6 mm at a spinneret temperature of 280 C. and a polyethylene composition:polyethylene terephthalate of 1:3 (mass ratio) to perform conjugate melt spinning. The obtained yarn in which 128 core-sheath composite filaments were bundled was subjected to cooling, stretching and relaxation treatments by conventional means to prepare multi-filament yarn having 1830 dtex/128 filaments.

[0025] The obtained multi-filament yarn was twisted with a twist number of 60 T/m and introduced into an 8-square braiding machine to prepare an 8-yarn braid. Then, under conditions of a temperature of 180 C. and a time period of 2 minutes, the sheath components of the core-sheath composite filaments in the braid were melt-bonded to each other to prepare a thermoformed article which was integrated as a whole. This thermoformed article had excellent abrasion resistance.

[0026] In addition, three reeds made of stainless steel (44 reed dents/inch) were prepared and arranged in parallel, and the position of the reed in the middle was displaced such that the multi-filament yarn was passed through the reed in the middle at an angle of 45. In this situation, the multi-filament yarn was run for 10 minutes at a speed of 1000 m/min. After that, when each reed was observed with a microscope, shavings were attached, but the amount was very small.