Process for producing needle-punched nonwoven fabric

Abstract

[Problem] 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: 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, isophthalic acid, and diethylene glycol, wherein, in the sheath, a molar ratio of ethylene glycol to diethylene glycol is within a range of 10:0.05 to 0.5 and a molar ratio of isophthalic acid to adipic acid to terephthalic acid is within a range of 0.04 to 0.6:1:1 to 10, needle-punching the web to three-dimensionally interlacing the sheath-core composite fibers; and heating and pressing the needle-punched nonwoven fabric to form a desired shape.

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. The process according to claim 1, wherein the desired shape is three dimensional stereoscopic shape.

4. The process according to claim 1, wherein the sheath-core composite fibers are melted with each other by heating and pressing the sheath components to soften or melt.

5. The process according to claim 1, wherein the needle-punched nonwoven fabric is simultaneously heated and pressed.

6. A process for producing an embossed nonwoven fabric, which comprises the following steps: 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, isophthalic acid, and diethylene glycol, wherein, in the sheath, a molar ratio of ethylene glycol to diethylene glycol is within a range of 10:0.05 to 0.5 and a molar ratio of isophthalic acid to adipic acid to terephthalic acid is within a range of 0.04 to 0.6:1:1 to 10, needle-punching the web to three-dimensionally interlace the sheath-core composite fibers, thus obtaining a needle-punched nonwoven fabric; and passing the needle-punched nonwoven fabric 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.

7. The process according to claim 1, wherein the needle-punched nonwoven fabric is heated and then pressed.

Description

EXAMPLE 1

(1) 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.

(2) 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

(3) 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 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.

(4) 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

(5) 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.

(6) 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

(7) 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.

(8) 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.