JP2587706B2 - Composite fiber and nonwoven fabric - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a composite fiber composed of low-melting syndiotactic-1,2-polybutadiene and polypropylene and a nonwoven fabric having a high sliding friction resistance using the composite fiber. .

(Prior art) Syndiotactic-1,2-polybutadiene (hereinafter SBD)
Abbreviated as) indicates an intermediate property between rubber and plastic, and a fiber having high frictional resistance is obtained.

As a method for producing a fiber, JP-A-48-33119, JP-B-51-33207 discloses a method of melt-spinning SBD using a heat stabilizer, and USP Nos. 3431875, 3950582 and 4085175.
There is known a method of obtaining fibrillated fibers from a film of an olefin polymer having 2 to 8 carbon atoms described in each specification. As a method for producing nonwoven fabric, Japanese Patent Application Laid-Open No. 56-123442
In Japanese Patent Laid-Open Publication No. H10-175, there is described a method for forming a nonwoven fabric from a fiber formed by fibrillating SBD having a melting point of 75 to 90 ° C.

(Problems to be Solved by the Invention) SBD has an unsaturated ethylene group in the side chain at a high density and is thermally unstable and easily generates intermolecular cross-links by the heat of melt spinning and gels. There is a drawback that the property is bad. In addition, there was also a problem that a thin fiber could not be obtained due to inferior fiber-forming ability as compared with a general α-olefin, and a web could not be formed through a card due to high rubber elasticity.

(Means for Solving the Problems) The present inventors have found that the temperature at which SBD causes significant gelation due to thermal crosslinking is about 200 ° C. or higher, and melt spinning at a lower temperature is required for more stable continuous spinning. I knew it was good. In addition, it was found that SBD has good adhesiveness to polypropylene, and that these composite fibers have good spinning and drawing properties, and that the rubber elasticity of SBD is suppressed, so that it is easy to handle as a fiber. It was also found that the spinning step was stable when the difference between the melting points of polypropylene and SBD was at least 10 ° C., leading to the present invention.

The present invention has a melting point T ° C. of 75 ≦ T <150 and a melt index (MI; according to JIS-K7210; temperature 190 ° C., weight 2169 g).
Is a syndiotactic-1,2-polybutadiene having a melting point of 100 ≦ m ≦ 165 and m ≦ T + 10, and a melt index (under the same conditions as the first component). 20-150 g of a second component which is polypropylene, wherein the first component and the second component have a cross-sectional area ratio of 30:70
7070: 30, and wherein the first component occupies 30% or more of the fiber surface.

The first component, SBD, has a melting point lower than that of polypropylene by 10 ° C. or more. The melting point of SBD is preferably 75-120 ° C,
The temperature is more preferably 80 to 110 ° C. At this time, the crystallinity of SBD is 15 to 50%. The melt index (MI; JIS
According to -K7210, temperature 190 ℃, weight 2169g) is 20 ~ 150g / 10
Min, more preferably 40 to 120 g / 10 min.

The polypropylene of the second component refers to a substantially homopolymer of propylene, a copolymer with other monomers or a three-component copolymer, and the like. Since the spinning temperature is set to less than 200 ° C., the melting point (m ° C.) Is preferably 100 ≦ m ≦ 165, more preferably 15
0 ≦ m ≦ 165. The MI of the polypropylene is 20 to 150 g / 10 min, preferably 30 to 70 g / 10 min under the same conditions as for SBD.

Polypropylene is usually spun at around 230 ° C., at which temperature the polymer has good melt flow properties. However, polybutadiene undergoes thermal cross-linking exceeding 200 ° C. and becomes gelled, resulting in frequent thread breakage. In the present invention, since the polymer of the first component and the second component of the conjugate fiber is selected as described above, polypropylene shows good melt fluidity even at a spinning temperature lower than usual, and polybutadiene can be thermally crosslinked. There is no.

As described above, since SBD is liable to undergo thermal crosslinking at a temperature exceeding 200 ° C., the spinning temperature (T ° C.) is set to 200 ° C. and is a temperature 20 ° C. higher than the melting point of polypropylene, preferably 165 ≦ T ≦ 200. And more preferably 175 ≦ T ≦ 185.

When the difference in melting point between SBD and polypropylene is 10 ° C. or more, the spinning process becomes good, but the heat bonding temperature for forming the conjugate fiber of the present invention into a nonwoven fabric is a low melting point component, SB.
Desirably, the temperature is 10 ° C. or higher than D and 10 ° C. or lower than polypropylene, which is a high melting point component. Therefore from this point SB
The difference in melting point between D and polypropylene is preferably at least 20 ° C.

Such a first component and a second component have a cross-sectional area ratio of the composite fiber of 30:70 to 70:30, and the first component has a surface area of the composite fiber of 30:70 to 70:30.
% Is necessary in order to obtain a suitable sliding friction resistance and thermal adhesiveness. If the amount of SBD exceeds 70% by weight, the rubber elasticity of the composite fiber becomes large, and the handling property in the process such as card passing property becomes poor.

The composite fiber can be used alone or with other fibers, such as cotton,
30% by weight or more of cellulose fiber such as rayon, polyester fiber, polyamide fiber or other polyolefin fiber not containing SBD is mixed and heat-bonded as a card web at a temperature not lower than the melting point of SBD by a usual method. It can be.

(Effect of the Invention) According to the present invention, fibers utilizing the frictional resistance and thermal adhesiveness of SBD can be obtained, and a nonwoven fabric using the same can be used.

(Example) Syndiotactic-1,2-polybutadiene (manufactured by Japan Synthetic Rubber Co., Ltd., trade name: JSR-RBT-871) having a melting point of 90 ° C and MI of 45 was used as the first component (sheath component) as SBD. A core / sheath composite fiber having a composite ratio of 50:50 was spun using a commercial product having a melting point of 160 ° C. and MI45 as polypropylene as two components (core component). The spinneret uses a composite fiber type with 700 holes and discharges 240 g /
Spinning at a spinning temperature of 180 ° C and spinning in hot water at 60 ° C
After stretching by a factor of two or more, mechanical crimping was applied and dried to obtain staples having finenesses of 2, 4 and 6 deniers and a fiber length of 76 mm.

The staple was passed through a roller card to form a web, and then heat-treated at 110 ° C. for 1 minute with a hot-air dryer to melt the sheath component SBD to form a heat-bonded nonwoven.

Examples 4 to 7 SBD as melting point 90 ° C., MI 120, 80, 20 and melting point 80 ° C.
A core-sheath type composite fiber and a nonwoven fabric thereof were obtained in the same manner as in Example 1 except that the syndiotactic-1,2-polybutadiene of MI45 was used. Only Example 7 was spun at a spinning temperature of 190 ° C.

Examples 8 to 9 In the same manner as in Example 1, except that the composite ratio was changed to 70:30 and 30:70, core-sheath type composite fibers and their nonwoven fabrics were obtained.

Comparative Example 1 The single fiber of SBD used in Example 1 was melt-spun,
Many NEPs were generated due to poor card passing properties, and the nonwoven fabric was not formed.

Comparative Example 2 A heat-bonded nonwoven fabric was obtained using a core-sheath composite fiber of polypropylene (PP) and polyethylene (PE) as the composite fiber.
Table 1 shows the physical properties of the fibers and nonwoven fabric obtained in each of the above Examples and Comparative Examples.

In the table, the card passability indicates that no NEP occurs,
A mark where a large number of chips are generated is indicated by x. The sliding frictional resistance of the nonwoven fabric was represented by を when the nonwoven fabric was placed on a smooth glass plate and slid when pressed down from above with a finger, and x when slippery.

(Effect of the Invention) The SBD conjugate fiber of the present invention has high sliding friction resistance, and a nonwoven fabric using the same can be widely used for household and industrial use.

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Claims (2)

(57) [Claims] 1. A melting point T ° C. is 75 ≦ T <150, and a melt index (MI; according to JIS-K7210; temperature 190 ° C., weight 2169 g)
Is a syndiotactic-1,2-polybutadiene having a melting point of 100 ≦ m ≦ 165 and m ≦ T + 10, and a melt index (under the same conditions as the first component). 20-150 g of a second component which is polypropylene, wherein the first component and the second component have a cross-sectional area ratio of 30:70
7070: 30, and the first component occupies 30% or more of the surface area. 2. A non-woven fabric which is heat-bonded with a first component containing at least 30% by weight of the conjugate fiber according to claim 1.