JP2003193332A - Sheath-core conjugate fiber and elastomer/fiber composite material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheath-core conjugate fiber having good intimacy between the sheath and the core, high interfacial strength between the sheath and the core and good intimacy with rubber and the like and realizing high reinforcing effect with compounded to elastomer compositions such as rubber composition, and to provide an elastomer/fiber composite material having high strength and rigidity and reinforced with the sheath-core conjugate fiber. <P>SOLUTION: This sheath-core conjugate fiber comprises a core comprising a thermoplastic resin and a sheath comprising a polyolefin. And the elastomer/ fiber composite material compounded with the sheath-core fiber is provided. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core-sheath type composite fiber and an elastic material / fiber composite material, and particularly to a core-sheath type composite fiber suitable for compounding in a rubber composition, and such a core-sheath type composite fiber. The present invention relates to an elastic material / fiber composite material containing fibers and an elastic material composition such as a rubber composition.

[0002]

2. Description of the Related Art Core-sheath type composite fibers having a core portion and a sheath portion made of different polymers are widely used as interior materials, filters, clothing materials, etc. in the form of non-woven fabric or woven fabric. . However, the conventional core-sheath type composite fiber is not used as a high-strength reinforcing material because the strength of the interface between the core and the sheath is low.

On the other hand, in the molding process of a rubber composition, various fibers such as polyamide and polyester are reinforced in order to improve the physical properties of the rubber composition. However, the interfacial strength between the fiber and the rubber composition is increased. Therefore, the strength of the fiber cannot be sufficiently contributed to the reinforcement of the rubber composition.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a core-sheath type composite fiber suitable for reinforcing an elastic material composition such as a rubber composition, and an elastic material / fiber composite material reinforced by the core-sheath type composite fiber. The purpose is to provide.

[0005]

The core-sheath type composite fiber of the present invention has a core and a sheath, the core contains a thermoplastic resin, and the sheath contains a polyolefin. Is characterized by.

The polyolefin-containing sheath has good compatibility with the core containing the thermoplastic resin and also has good compatibility with the elastic material composition such as a rubber composition. Therefore, this core-sheath type composite fiber is suitable for reinforcing an elastic material composition such as a rubber composition.

Particularly, since the sheath portion contains polyethylene having a portion capable of crosslinking with an elastic material such as a rubber component serving as a matrix, the core-sheath type composite fiber and the elastic material composition such as a rubber composition are formed. It is possible to enhance the adhesiveness and the strength of an elastic material composition such as a rubber composition.

When the polyolefin constituting the sheath portion has a specific functional group, the strength of the interface between the sheath portion and the core portion becomes high, and the core-sheath type composite fiber becomes high in strength.

The elastic material / fiber composite material of the present invention is obtained by reinforcing an elastic material composition such as a rubber composition with a core-sheath type composite fiber whose sheath portion contains polyolefin. When the elastic material composition such as the rubber composition is thus reinforced with the core-sheath type composite fiber, the strength of the interface between the sheath portion and the core portion and the sheath portion and the elastic material composition are selected by selecting the material of the sheath portion. It is possible to obtain both a high strength elastic material / fiber composite material by enhancing both the compatibility with objects. As the core-sheath type composite fiber, the core-sheath type composite fiber of the present invention is suitable.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the core-sheath type composite fiber and the elastic material / fiber composite material of the present invention will be described in detail below.

The core-sheath type composite fiber of the present invention has a core portion containing a thermoplastic resin and a sheath portion containing a polyolefin.

The thermoplastic resin constituting the core may be one or more of polyamide, polyester, polyolefin, polyurethane, polycarbonate, polymethylmethacrylate, polyphenylene ether, a mixture of polyphenylene ether and styrene, polyvinyl alcohol and the like. However, polyamide or polyester is preferable in terms of spinnability, strength, cost and the like. From the viewpoint of workability, the melting point of the thermoplastic resin forming the core is 200
It is preferably at least ° C.

On the other hand, as the polyolefin constituting the sheath, polyethylene (low density to high density polyethylene),
One or more of polypropylene, ethylene-propylene copolymer and the like can be mentioned, but polyethylene, particularly from the viewpoint of interface strength with an elastic material composition such as a rubber composition, heat resistance and durability, High density polyethylene is preferred. The melting point of the polyolefin is preferably 120 to 170 ° C. The melting point of polyolefin is 120 ℃
If it is less than 170 ° C., there is a problem in heat resistance, and if it exceeds 170 ° C., the adhesiveness with an elastic material composition such as a rubber composition is deteriorated.

The constituent material of the sheath portion may include, for example, a thermoplastic resin suitable for forming the core portion, as long as the gist of the present invention is not impaired. In this case, the content of the thermoplastic resin in the constituent material of the sheath is
If the amount is too large, the effect of improving the conformability of the polyolefin of the sheath portion with the elastic material composition such as the rubber composition of the matrix is impaired. Therefore, it is preferably 20% by weight or less.

The polyolefin constituting the sheath is preferably a modified polyolefin resin having a functional group from the viewpoint of the interfacial strength between the core and the sheath. The functional group may be an acid anhydride group or a carboxyl group. , Acid amide group, epoxy group, hydroxyl group, ester group and the like, but when the core material is polyamide and / or polyester, this functional group is preferably an acid anhydride group. The higher the modification rate by the functional group, the stronger the effect of improving the interfacial strength between the core and the sheath due to the introduction of the functional group is strongly expressed, but the higher the modification rate, the more the properties of the polyolefin as the sheath material tend to be impaired. Therefore, 0.2 to 1
It is preferably 0%, particularly preferably 0.5 to 3%. Here, the modification rate is represented by the weight ratio of the functional group to the total weight of the polyolefin.

When the core-sheath type composite fiber of the present invention is used as a reinforcing fiber of a rubber composition, in order to improve the interfacial strength between the core-sheath type composite fiber and the rubber composition, it is used in a polyolefin of a sheath material. Preferably has a portion capable of crosslinking with the rubber component, and particularly, the sheath material preferably comprises polyethylene having a portion capable of crosslinking with the rubber component in an amount of 20% by weight.
The above content is more preferably 35 to 70% by weight.

The fiber diameter of the core-sheath type composite fiber of the present invention is not particularly limited and is appropriately determined according to the application.

Further, regarding the ratio of the core portion and the sheath portion constituting the core-sheath type composite fiber, if the ratio of the core portion which bears the strength is too small, the strength etc. as the core-sheath type composite fiber is impaired and the surface If the proportion of the sheath portion for improving the conformability is small, the effect of improving the conformability cannot be sufficiently obtained,
The weight ratio of the core portion to the sheath portion is preferably 10: 1 to 1: 1.

Such a core-sheath type composite fiber can be easily produced by using a spinning machine having two extruders and performing a composite spinning at a discharge amount having the above weight ratio.

The core-sheath type composite fiber of the present invention is particularly effective as a reinforcing fiber of an elastic material composition such as rubber, but is not limited to this application. When it is used as a reinforcing fiber of an elastic material composition, it may be dispersed in a matrix in the form of a short fiber, a non-woven fabric,
Alternatively, the matrix may be impregnated as a knitted fabric (woven or knitted fabric), or the long fibers may be aligned and contained in the matrix.

Next, the elastic material / fiber composite material of the present invention will be described.

The elastic material / fiber composite material of the present invention is a core-sheath type composite fiber having a core portion and a sheath portion, and the sheath portion containing polyolefin, preferably the core-sheath type composite fiber of the present invention. It is reinforced.

The elastic material used in the elastic material / fiber composite material of the present invention is not particularly limited, and can be appropriately selected from known thermosetting and thermoplastic elastic materials according to the application. As the thermosetting elastic material, natural rubber, polyisoprene rubber, polybutadiene rubber, styrene butadiene rubber, butyl rubber, chloroprene rubber, acrylonitrile-butadiene rubber, acrylic rubber, ethylene-vinyl acetate copolymer, ethylene propylene rubber, halogenated Vulcanizable rubber components such as butyl rubber are preferred. These elastic materials can be used alone or in combination of two or more.

The core-sheath type composite fiber contained in the elastic material / fiber composite material of the present invention may be dispersed in the matrix as a short fiber having a fiber length of about 0.2 to 5 mm. They may be aligned and arranged substantially parallel to each other to form a composite with the matrix. Further, it may be contained as a nonwoven fabric or a woven / knitted product of core-sheath type composite fibers.

The content of the core / sheath type composite fiber in the elastic material / fiber composite material of the present invention can be appropriately selected depending on the compounding form of the core / sheath type composite fiber and the use of the elastic material / fiber composite material. The larger the content of the core-sheath type composite fiber, the greater the reinforcing effect can be obtained. However, if the content is large, the properties inherent to the elastic material composition such as elasticity are impaired, and the moldability tends to decrease. For example, when the elastic material / fiber composite material of the present invention is used as a tire molding material, the elastic material 100 such as a rubber component is used.
The blending amount of the core-sheath type composite fiber is preferably about 2 to 40 parts by weight with respect to parts by weight.

In the elastic material composition used in the present invention, if necessary, fillers such as carbon black and silica, softening agents such as aroma oil and spindle oil, antiaging agents, vulcanizing agents,
Appropriate amounts of various compounds to be compounded with an elastic material composition such as a usual rubber composition such as a vulcanization accelerator, a plasticizer and a foaming agent can be appropriately compounded.

When the core-sheath type composite fiber is a short fiber, the elastic material composition used in the present invention is kneaded together with other necessary components in a predetermined composition so that the core-sheath type composite fiber is a long fiber, a non-woven fabric or a knitted fabric. In such a case, a molded product can be obtained by compounding the elastic material composition and the core-sheath type composite fiber, which are kneaded in a predetermined composition, and vulcanizing and molding according to a conventional method.

The elastic material / fiber composite material of the present invention as described above can be effectively applied to various rubber products such as tires, rubber belts, rubber rollers, anti-vibration rubbers, golf balls and laminated rubbers. An elastic product with high characteristics can be obtained due to the desired strength and rigidity.

[0029]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples below.

Example 1 A core-sheath type composite fiber was produced using the following core material and sheath material.

Core material: "Ube Nylon 1030B" manufactured by Ube Industries, Ltd. (melting point: 215 to 220 ° C, molecular weight: 3)
50,000, specific gravity: 1.14) Sheath material: high-density polyethylene with a maleic acid modification rate adjusted to 2% (high-density polyethylene "HJ" manufactured by Mitsubishi Chemical Corporation)
560 "(melting point: 136 ° C, specific gravity: 0.964) and maleic acid-modified high-density polyethylene" UMEX 2000 "(weight average molecular weight: about 16, manufactured by Sanyo Kasei Co., Ltd.)
000, density: 0.95 g / cm ³ , acid value: 27, softening point: about 107 ° C. (ring and ball system))
00 ”:“ HJ560 ”= 8: 100, approximately 17
The mixture was kneaded and extruded with a twin-screw extruder under the condition of 0 ° C. to obtain pellets. )

Using the above materials and a spinning machine consisting of two extruders, the discharge temperature on the nylon side was 250 ° C., the discharge temperature on the polyethylene side was 180 ° C., and the discharge amount on the nylon side was 3 g / mi.
n, polyethylene-side discharge rate of 1 g / min, core-sheath type composite spinning was performed, and further drawing was performed at a winding speed of 2 km / min, and core (nylon): sheath (polyethylene) = 3: 1 (weight ratio) and fiber diameter A core-sheath type composite fiber A of about 15 μm was obtained.

Regarding the obtained core-sheath type composite fiber A, 23
Tensile strength and elongation at break were measured in an environment of ° C and relative humidity of 50%, and the results are shown in Table 2.

Using this core-sheath type composite fiber A as a reinforcing material, a rubber composition was prepared by kneading with the compounding formulation shown in Table 1 below, and this was vulcanized and molded to obtain a sheet having a thickness of 1 mm. The tensile strength and elongation at break of this sheet were measured, and the results are shown in Table 2. The core-sheath type composite fiber A was used after being cut to a length of 1 mm. Further, the tensile strength and the elongation at break were measured on a punched test piece of dumbbell No. 3 using an Instron universal testing machine in accordance with JIS K6301-1995.

[0035]

[Table 1]

Example 2 A core-sheath composite fiber B was produced in the same manner as in Example 1 except that only high density polyethylene "HJ560" manufactured by Mitsubishi Chemical Corporation was used as the sheath material. The core-sheath composite fiber B was measured for tensile strength and elongation at break in the same manner as in Example 1, and the results are shown in Table 2. Also,
In the same manner as in Example 1, the tensile strength and elongation at break of the rubber sheet when blended in the rubber composition were measured, and the results are shown in Table 2.
It was shown to.

Comparative Example 1 Using only "Ube Nylon 1030B" manufactured by Ube Industries, Ltd. used as the core material in Example 1, the discharge temperature was 250 ° C., the discharge rate was 4 g / min, and the winding speed was 2 k with one extruder.
Spinning was performed at m / min to produce a nylon single fiber having a fiber diameter of about 15 μm. The tensile strength and elongation at break of the obtained nylon single fiber were measured, and the results are shown in Table 2. Further, in the same manner as in Example 1, the tensile strength and the elongation at break of the rubber sheet when blended with the rubber composition were measured,
The results are shown in Table 2.

[0038]

[Table 2]

Comparative Example 2 Only the high-density polyethylene "HJ560" manufactured by Mitsubishi Chemical Co., Ltd. used as the sheath material in Example 1 was used, and the discharge temperature was 250 ° C., the discharge rate was 4 g / min, and the winding speed was one extruder. Spinning was performed at 2 km / min to produce polyethylene single fibers having a fiber diameter of about 15 μm. With respect to the obtained polyethylene single fiber, the tensile strength and the elongation at break of the rubber sheet when compounded into the rubber composition were examined in the same manner as in Example 1. It was found that both the tensile strength and the elongation at break were substantially improved. There wasn't.

In the above Examples 1 and 2 and Comparative Examples 1 and 2, the fracture surface of the rubber sheet after the test was observed by using a scanning microscope. Examples 1 and 2 using the core-sheath type composite fiber were observed. In Example 1, so-called rubber adhesion, in which dust was attached to the fiber surface, was observed, but in Comparative Example 1 in which nylon single fiber was used, the fiber surface was clean and rubber adhesion was not observed. Further, in Comparative Example 2 using polyethylene single fiber, the fiber was changed to spherulite.

As is clear from the above results, the tensile strength of the nylon single fiber of Comparative Example 1 is superior to that of the core-sheath type composite fibers of Examples 1 and 2, but when it is compounded in the rubber composition. Regarding the reinforcing effect, the core-sheath type composite fiber is significantly superior to the nylon single fiber and the polyethylene single fiber. This is because the core-sheath type composite fiber of the present invention has good compatibility between the core and the sheath, and also has good compatibility with the sheath and the rubber. It is further enhanced by introducing a group.

[0042]

As described in detail above, according to the present invention, the core portion and the sheath portion are well compatible with each other, the strength of the interface between the core portion and the sheath portion is high, and the elastic material such as rubber is compatible. And a core-sheath type composite fiber capable of obtaining a high reinforcing effect when compounded in an elastic material composition such as a rubber composition, and high strength and high rigidity reinforced by such a core-sheath type composite fiber An elastic / fiber composite is provided.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F072 AA02 AB04 AB05 AB06 AB29                       AB30 AB33 AD02 AL01                 4L041 AA08 BA02 BA05 BA21 BC20                       BD01 BD20 CA37 CA63 DD05                       DD14 DD18                 4L048 AA15 AA24 AA28 AA42 AA48                       AA49 AB07 AC00 AC09 AC10                       CA01 CA02 DA41 DA42 DA44

Claims (14)

[Claims] 1. A core-sheath type composite fiber having a core portion and a sheath portion, the core portion containing a thermoplastic resin, and the sheath portion containing a polyolefin. 2. The thermoplastic resin according to claim 1, wherein the thermoplastic resin forming the core is one or more of polyamide, polyester, polyolefin, polyurethane, polycarbonate, acryl, polyphenylene ether and polyvinyl alcohol. Core-sheath type composite fiber. 3. The core-sheath type composite fiber according to claim 1 or 2, wherein the polyolefin constituting the sheath portion contains one or more of polyethylene, polypropylene and an ethylene-propylene copolymer. 4. The core-sheath type composite fiber according to claim 3, wherein the polyolefin constituting the sheath portion contains high-density polyethylene. 5. The core-sheath type composite fiber according to claim 3 or 4, wherein the polyolefin constituting the sheath portion contains polyethylene having a portion capable of being crosslinked with a rubber component. 6. The core-sheath type composite fiber according to any one of claims 1 to 5, wherein the polyolefin forming the sheath has a functional group. 7. The core-sheath composite according to claim 6, wherein the functional group is one or more of an acid anhydride group, a carboxyl group, an acid amide group, an epoxy group, a hydroxyl group and an ester group. fiber. 8. The thermoplastic resin according to claim 7, wherein the thermoplastic resin constituting the core is polyamide and / or polyester,
A core-sheath type composite fiber, wherein the functional group is an acid anhydride group. 9. An elastic / fiber composite material comprising a core-sheath type composite fiber having a core portion and a sheath portion, the sheath portion containing a polyolefin, and an elastic material composition. 10. The elastic material / fiber composite material according to claim 9, wherein the elastic material composition is a rubber composition. 11. The elastic material / fiber composite material according to claim 9 or 10, wherein the core-sheath type composite fiber is the core-sheath type composite fiber according to any one of claims 1 to 8. 12. The elastic / fiber composite material according to claim 9, wherein the core-sheath type composite fibers are combined as short fibers. 13. An elastic material / fiber composite material according to claim 9, wherein the core-sheath type composite fibers are compounded as a nonwoven fabric made of the core-sheath type composite fibers. 14. The elastic / fiber composite material according to claim 9, wherein the core-sheath type composite fibers are compounded as a woven or knitted product made of the core-sheath type composite fibers.