PROCESS FOR PRODUCING NEEDLE-PUNCHED NONWOVEN FABRIC

Abstract

To provide a process for producing a needle-punched nonwoven fabric with which, when finished by embossing, it is possible to obtain a hardly fluffing and distinct rugged pattern. [Solution] Sheath-core composite fibers are accumulated and a fibrous web is formed. The core component of the sheath-core composite fiber is formed from a copolymer of ethylene glycol and terephthalic acid. The sheath component is formed from a copolymer of ethylene glycol, adipic acid, terephthalic acid, isophthalic acid and diethylene glycol. The sheath-core composite fibers are three dimensionally interlaced with each other by needle-punching the web, to obtain the needle-punched nonwoven fabric. The needle-punched nonwoven fabric is passed through heated embossed roll to provide a rugged pattern on a surface. During the process, the sheath component are softening melted and melt bonded between the sheath-core composite fibers to obtain an embossed nonwoven fabric having a distinct rugged pattern.

Claims

1. A process for producing a needle-punched nonwoven fabric, which comprises the following steps: a first step of forming a web by accumulating sheath-core composite fibers in which the core is formed from a copolymer of ethylene glycol and terephthalic acid and the sheath is formed from a copolymer of ethylene glycol, adipic acid, terephthalic acid and isophthalic; acid and/or diethylene glycol, a second step of needle-punching the web to three-dimensionally interlacing the sheath-core composite fibers.

2. The process of claim 1, wherein the sheath-core composite fiber is either sheath-core composite continuous filament or sheath-core composition staple fiber.

3. A process for producing a thermoformed nonwoven fabric, which comprises the following steps: a first step of forming a web by accumulating sheath-core composite fibers in which the core is formed from a copolymer of ethylene glycol and terephthalic acid and the sheath is formed from a copolymer of ethylene glycol, adipic acid, terephthalic acid and isophthalic acid; and/or diethylene glycol, a second step of needle-punching the web to three-dimensionally interlacing the sheath-core composite fibers, thus obtaining a needle-punched nonwoven fabric the needle-punched nonwoven fabric is then heated and pressed to form a desired shape.

4. The process according to claim 3, wherein the desired shape is three dimensional stereoscopic shape.

5. The process according to claim 3, wherein the sheath-core composite fibers are melted with each other by heating and pressing the sheath components to soften or melt.

6. The process according to claim 3, wherein the needle-punched nonwoven fabric is simultaneously heated and pressed, or heated and then pressed.

7. A process for producing an embossed nonwoven fabric, which comprises the following steps: a first step of forming a web by accumulating sheath-core composite fibers in which the core is formed from a copolymer of ethylene glycol and terephthalic acid and the sheath is formed from a copolymer of ethylene glycol, adipic acid, terephthalic acid and isophthalic acid; and/or diethylene glycol, a second step of needle-punching the web to three-dimensionally interlace the sheath-core composite fibers, thus obtaining a needle-punched nonwoven fabric the needle-punched nonwoven fabric is then passed through a heated emboss roll to form a rugged pattern on a surface and to soften or melt the sheath components to bond the sheath-core composite fibers with each other.

Description

EXAMPLE 1

[0018] A copolymer of ethylene glycol and terephthalic acid (a melting point of 260 C.) was prepared as a core component. A copolymer of ethylene glycol, diethylene glycol, adipic acid, terephthalic acid and isophthalic acid (a melting point of 200 C.) was prepared as a sheath component. The diol components contained 99 mole % of ethylene glycol and 1 mole % of diethylene glycol, and the dicarboxylic acids contained 19 mole % of adipic acid, 78 mole % of terephthalic acid and 3 mole % of isophthalic acid. Both of the core component and sheath component were provided into a spinning apparatus having composite spinning holes and then melt spun to obtain a sheath-core composite continuous filament. The sheath-core composite continuous filament had a weight ratio of core component: sheath component=7:3. The filaments were introduced into an air sucker located under the spinning apparatus and rapidly sucked and thinned, followed by open filaments by an art-known opening devise to collect and to accumulate on a moving screen conveyer to obtains filamentous web. The filamentous web was conveyed to a needle-punching machine and needle-punched at a punch density of 90 punches/cm.sup.2 and a needle depth of 10 mm, to obtain a needle-punched nonwoven fabric having a weight of 300 g/m.sup.2.

[0019] The resulting needle-punched nonwoven fabric was passed between a flat roll and an embossed roll having a grain leather pattern with a depth of 0.4 mm and heat embossed at an embossed roll temperature of 130 C. and a roll linear pressure of 50 kg/cm. The resulting embossed nonwoven fabric had a distinct grain leather pattern and had excellent designed pattern with excellent rubbing resistance and sufficient softness.

Comparative Example 1

[0020] The copolymer obtained in Example 1 was prepared as core component. A copolymer of ethylene glycol, diethylene glycol, terephthalic acid and isophthalic acid (a melting point of 230 C.) was prepared as sheath component. In the copolymer constituting the sheath component, the diol component contained 99 mole % of ethylene glycol and 1 mole % of diethylene glycol, and the dicarboxylic acid included 92 mole % of terephthalic acid and 8 mole % of isophthalic acid. Both of the core component and sheath component were provided into a spinning apparatus having composite spinning holes and then melt spun to obtain a sheath-core composite continuous filament. The sheath-core composite continuous filament had a weight ratio of core component: sheath component=6:4. The filaments were introduced into an air sucker located under the spinning apparatus and rapidly sucked and thinned, followed by open filaments by an art-known opening devise to collect and to accumulate on a moving screen conveyer to obtains filamentous web. The filamentous web was conveyed to a needle-punching machine and needle-punched at a punch density of 90punches/cm.sup.2 and a needle depth of 10 mm, to obtain a needle-punched nonwoven fabric having a weight of 300 g/m.sup.2.

[0021] The resulting needle-punched nonwoven fabric was passed between a flat roll and an embossed roll having grain leather pattern with a depth of 0.4 mm and heat embossed at an embossed roll temperature of 200 C. and a roll linear pressure of 50 kg/cm. The resulting embossed nonwoven fabric had a distinct grain leather pattern, but when it was touched by a finger, had become fluffy in convex portions and had broken the bonding between the sheath-core composite filaments, thus making the rugged pattern indistinct. The needle-punched nonwoven fabric showed less softness than that of Example 1.

Comparative Example 2

[0022] Sheath-core composite staple fiber (available from Unitika Ltd., Number 2080, finess 4.4 dtex, fiber length 51 mm, core component: sheath component=1:1 weight ratio, sheath component having a melting point of 200 C.) was prepared. The core component of the sheath-core composite staple fiber was same with the copolymer of Example 1 and the sheath component was a copolymer of 99 mole % of ethylene glycol and 1 mole % of diethylene glycol as diol component and of 80 mole % of terephthalic acid and 20 mole % of isophthalic acid as dicarboxylic acid. The sheath-core composite staple fibers were opened and collected by a carding machine to obtain fibrous web which was then conveyed to a needle-punching machine and needle-punched at a punch density of 90 punches/cm.sup.2 and a needle depth of 10 mm, to obtain a needle-punched nonwoven fabric having a weight of 300 g/m.sup.2.

[0023] The resulting needle-punched nonwoven fabric was passed between a flat roll and an embossed roll having a grain leather pattern with a depth of 0.4 mm and heat embossed at an embossed roll temperature of 140 C. and a roll linear pressure of 50 kg/cm, but did not provide distinct rugged pattern, because the nonwoven fabric had large heat contraction and formed wrinkles.

Comparative Example 3

[0024] Polyester staple fiber (available from Unitika Ltd., Number 100, finess 2.0 dtex, fiber length 51 mm, a melting point of 260 C.) was prepared. 50% by weight of the polyester staple fibers and 50% by weight of the sheath-core composite staple fibers were uniformly mixed and were open-fibered and collected by a carding machine to obtain fibrous web which was immediately conveyed to a needle-punching machine and needle-punched at a punch density of 90 punches/cm.sup.2 and a needle depth of 10 mm, to obtain a needle-punched nonwoven fabric having a weight of 300 g/m.sup.2.

[0025] The resulting needle-punched nonwoven fabric was heat embossed as generally described in Comparative example 2, but did not provide a grain leather pattern, although it was soft. When it was touched by a finger, it became fluffy and showed poor rubbing resistance.