JP3032396B2 - Polyolefin-based conductive composite fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a polyolefin obtained by melting and mixing at least a part of a conductive conjugate fiber, in particular, a polyamide or polyester composition containing conductive particles and a modified polyolefin. The present invention relates to a conductive conjugate fiber.

[0002]

2. Description of the Related Art Nonwoven fabrics made of polyolefins such as polyethylene and polypropylene made of long or short fibers are inexpensive and have chemical resistance, so they are used as medical and sanitary materials, agricultural coating materials, and various filters. Widely used as materials, general packaging materials, civil engineering and building construction materials. However, since the nonwoven fabric is inherently hydrophobic, it tends to generate static electricity. Particularly, medical products such as surgical gowns and surgical masks, OA equipment members such as floppy disk liners and envelopes, and clean room gloves and the like. When applied to products, high antistatic properties (antistatic performance) are required.

[0003] In general, regarding a method for preventing static electricity of a fiber product such as a non-woven fabric, a conductive component containing a conductive carbon black or a conductive metal compound and a fiber-forming protective component (non-conductive component) are conventionally combined. There is a method of mixing a small amount of conductive conjugate fiber into a product, and excellent antistatic properties can be imparted. As such conductive composite fibers, those having various composite structures as shown in FIGS. 1 to 6 have been proposed and used. However, conductive components as shown in FIGS. 1 to 5 are exposed on the fiber surface. This type (exposed conductive component) is more frequently used than the core-shell type having a conductive component as a core and a protective component as a sheath as shown in FIG. 6 because of its excellent corona discharge property, that is, antistatic property. .

[0004]

SUMMARY OF THE INVENTION However, conventional conductive composite fibers of the type exposed to a conductive component may not be suitable for use as a polyolefin nonwoven fabric. For example, at the time of thermal bonding such as embossing, calendering, and the like, bonding between the constituent fibers of the nonwoven fabric, interlacing or patterning,
In the case of conductive fibers made of polyolefin material, polyolefin is also used as the binder polymer of the conductive component from the viewpoint of adhesiveness with the protective component. It often leads to significant degradation or loss. Also, conductive fibers other than polyolefins such as polyamides and polyesters have no affinity for polyolefins, so even if embossing or calendering is performed, the conductive fibers fall out of the nonwoven fabric during subsequent processing or product use. Often. As described above, a conductive composite fiber suitable for a polyolefin nonwoven fabric having a high adhesiveness to a polyolefin, a melting point and a softening point of a conductive component higher than that of the polyolefin, and having excellent antistatic properties has not yet been obtained. is the current situation. An object of the present invention is to provide a polyolefin-based conductive conjugate fiber suitable for a polyolefin nonwoven fabric that can be industrially produced.

[0005]

That is, the present invention provides at least a part of a conductive component comprising a polyamide or polyester composition containing conductive particles and a modified polyolefin obtained by graft-polymerizing an unsaturated carboxylic acid or a derivative thereof. A conductive conjugate fiber characterized by being compounded with a protective component comprising a melt-mixed polyolefin such that at least a part of the conductive component is exposed on the fiber surface.

[0006] In the present invention, the conductive component is composed of a polyamide or polyester having a melting point higher than that of polyolefin and conductive particles uniformly mixed and dispersed in a conventional manner. As the polyamide or polyester used for the conductive component, nylon 6, nylon 66, nylon 10, nylon 12, or the like, or a modified polyamide copolymer containing these as a main component, polyethylene terephthalate, polybutylene terephthalate, polyethylene oxybenzoate Or a modified polyester copolymer containing these as a main component. Above all, in order to prevent the conductive component from being melted and deformed or cut during the thermal processing of the polyolefin nonwoven fabric, the melting point or softening point must be 17 or less.
The temperature is preferably 0 ° C. or higher, and more preferably 200 ° C. or higher.

[0007] The conductive particles used in the present invention include:
Metal powders such as conductive carbon black, silver, nickel, copper, iron and alloys thereof, metal compounds such as copper sulfide, copper iodide, zinc sulfide, cadmium sulfide, tin oxide, zinc oxide, copper oxide, and zinc oxide Examples include metal oxide particles such as copper oxide, indium oxide, zirconium oxide, and tungsten oxide. Although many of the metal oxides are semiconductors close to insulators and often do not exhibit sufficient conductivity for the purpose of the present invention, a small amount of the second component (impurity) suitable for the metal oxide, usually 50 By a method such as addition of not more than 25% by weight, often not more than 25% by weight, conductivity is enhanced, and a material having sufficient conductivity for the purpose of the present invention can be obtained. As such a conductivity enhancer, metal oxides such as antimony oxide for tin oxide and aluminum, indium, germanium, and tin for zinc oxide can be used. Further, non-conductive inorganic particles, such as titanium oxide, zinc oxide, magnesium oxide, tin oxide, iron oxide, silicon oxide, and aluminum oxide, may have a conductive film of the above-described conductive metal oxide or metal compound formed on the surface thereof. Used. Among these conductive particles, conductive carbon black, conductive tin oxide doped with antimony, and titanium oxide coated with the same are particularly preferable because uniform particles having a small particle size can be easily obtained.

The conductivity of the conductive particles is in the form of a powder (50 kg).
/ Cm ² under pressure) with a specific resistance (volume resistivity) of 10 ⁴ Ω
cm or less, particularly preferably about 10 ² Ωcm or less,
Most preferably, it is about 10 ¹ Ωcm or less. Actually 10 ² ~
Those having a conductivity of about 10 ⁻³ Ωcm can be suitably used for the purpose of the present invention, but those having more excellent conductivity are more preferable.

The conductive particles must have a sufficiently small particle size. It is not impossible to use those having an average particle diameter of 1 to 2 μm, but usually those having an average particle diameter of 1 μm or less, particularly 0.5 μm or less, most preferably 0.3 μm or less are used. Those having a large particle diameter are liable to break during spinning and drawing, and in many cases, spinning is difficult.

The mixing ratio of the conductive particles to the polyamide or polyester varies depending on the properties and crystallinity of the polymer to be mixed, the type of the conductive particles, the conductivity, the particle shape, the particle size, and the like. % By weight, and particularly preferably from 15 to 80% by weight. If the amount is less than 10% by weight, conductivity often does not appear. On the other hand, if the content exceeds 85% by weight, it becomes difficult to uniformly disperse the particles in the polymer, and even if the particles can be dispersed with great effort, the fluidity of the polymer is lowered and spinning is hindered. The specific resistance of the conductive component needs to be less than 10 ⁷ Ωcm, preferably 10 ⁴ Ωcm or less, and more preferably 10 ² Ωcm.
cm or less is particularly preferred.

In the present invention, the protective component of the conjugate fiber is composed of a fiber-forming polyolefin obtained by melt-mixing at least a part of the modified polyolefin. The modified polyolefin is polyethylene, polypropylene, polybutene-
An unsaturated carboxylic acid or a derivative thereof is graft-polymerized on a polyolefin such as 1. Examples of unsaturated carboxylic acids or derivatives thereof include unsaturated carboxylic acids such as acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, and derivatives thereof, such as acid halides and amides. And imides, anhydrides, esters and the like, and specific examples thereof include maleic anhydride, monomethyl maleate, dimethyl maleate, maleic chloride, citraconic anhydride, citraconic chloride and the like. In particular, unsaturated dicarboxylic acids or anhydrides thereof are preferred.

The total amount of the unsaturated carboxylic acid or its derivative in the protective component is usually 0.1 to 10% by weight, preferably 0.5 to 7% by weight, most preferably 1 to 5% by weight based on the polyolefin. It is. Total weight is 0.1% by weight
If it is less than 30, the adhesion to the polyamide or polyester forming the conductive component is deteriorated, and the conductive component and the protective component are peeled off during spinning and drawing, making it difficult to form a yarn. on the other hand,
If the total amount is 10% by weight or more, heat stability or spinnability as a protective component may be undesirably reduced.

The conductive component and the protective component further include a dispersant (waxes, polyalkylene oxides, various surfactants, organic electrolytes, etc.), a coloring agent, a heat stabilizer (an antioxidant, an ultraviolet absorber). Etc.), flowability improvers and other additives can be added.

The cross-sectional shape of the composite fiber of the present invention may be circular or non-circular, and is not particularly limited, but the composite form of the conductive component and the protective component is important. That is, in the cross-sectional shape of the conjugate fiber, it is important that at least a part of the conductive component is exposed on the fiber surface. 1 to 5 are cross-sectional views of a composite fiber showing an example of a composite structure that can be used in the present invention. In the figure, 1 indicates a conductive component and 2 indicates a protective component. 1 is an example of a three-layer type, FIG. 2 is an example of a radial type, FIG.
4 shows an example of a keyhole type, FIG. 4 shows an example of a multiplexed keyhole type, and FIG. 5 shows an example of a parallel (side-by-side) type. Antistatic performance (antistatic property) by exposing conductive component to fiber surface
An excellent conductive fiber can be obtained. Regarding the compounding ratio (cross-sectional area occupancy) of the conductive component, the conductive component containing a large amount of conductive particles tends to have poor spinnability (spinnability) and high elongation. And preferably 3
0% or less, more preferably 2 to 20%.

[0015]

The present invention will be specifically described below with reference to examples.

Example 1 A conductive polymer composition obtained by mixing and dispersing 35% by weight of conductive carbon black in nylon 6 having a molecular weight of 14000 was prepared by using CP.
Let it be 1. Melt flow rate value (Test method ASTM
D1238) A conductive polymer composition obtained by mixing and dispersing 35% by weight of conductive carbon black in polypropylene having a melting point of 150 ° C. and a melting point of 35 g / 10 minutes is referred to as CP2. A modified polypropylene having a melt flow rate of 17 g / 10 min and a melting point of 163 ° C. obtained by graft polymerization of maleic anhydride at 5% by weight is designated as P1. Nylon 6 with a molecular weight of 16000
Let it be 2. A polypropylene having a melt flow rate of 23 g / 10 minutes and a melting point of 150 ° C. is designated as P3.

CP1 and CP2 are conductive components, and P1 and P2
2, P3 was used as a protective component and melt-spun in a composite structure as shown in Table 1. The composite ratio (volume ratio) of both components is set to 1:10, and the mixture is spun from an orifice having a diameter of 0.25 mm at a spinning temperature of 270 ° C. and wound at a speed of 700 m / min while cooling oiling. Then, on a stretching roller at 85 ° C., 2.4.
The film was stretched twice, heat-treated on a hot plate at 120 ° C., and wound to obtain 72 denier / 24 filaments. further,
These filaments are plied to about 100,000 denier, and about 15 filaments / 25m are processed by a stuffer type crimping machine.
m, and cut into 51 mm lengths to obtain staples Y1 to Y4. Single yarn 1c of staples Y1 to Y4
shows an electric resistance per m in Table 1, both 10 ⁷
It had good conductive performance on the order of Ω / cm.

Next, staples Y1 to Y4 were separately prepared, 1.5 denier single yarn, 15 staples / 25 mm crimp,
A 1 mm cut length polypropylene (melt flow rate value: 23 g / 10 min) staple was blended at a blending ratio of 10% by weight to produce a basis weight of 50 g / m ² web. The lattice pattern was embossed to make a nonwoven fabric. Table 1 shows the results of measuring the surface resistivity of these nonwoven fabrics. The surface resistivity of the nonwoven fabric of Y1 was 2.3 × 10 ⁷ Ω, which was excellent in conductivity, but the nonwoven fabric of Y2, Y3, and Y4 had a surface resistivity of 10 × 10 ⁷ Ω.
^The conductivity was poor in the order of ¹⁰ to 10 ¹¹ Ω. When the surface of the nonwoven fabric of Y2 was rubbed with a flannel cloth, many conductive fibers were removed. When the surface of the nonwoven fabric of Y4 was observed with a scanning electron microscope, the conductive component of the conductive fiber was deformed or cut.

[0019]

Example 2 Light gray blue color obtained by mixing and firing 1.5% antimony oxide to titanium oxide particles having a 15% tin oxide film on polyethylene terephthalate having a molecular weight of 15000 and a melting point of 257 ° C. The conductive component obtained by mixing and dispersing 65% by weight of a conductive powder having an average particle size of 0.25 μm and a specific resistance of 4.0 Ωcm is referred to as CP3. CP3 is a conductive component,
P1 was used as a protective component and compounded at a compounding ratio of 1/10 into a side-by-side type as shown in FIG.
A staple Y5 was prepared under the same conditions as in Example 1 except that the temperature was changed to ° C. The electric resistance value of Y5 is 3.2 × 10 ⁷ Ω / cm.
And had good conductivity. Y5 was mixed with the polypropylene staple of Example 1 at a mixing ratio of 10% by weight,
A nonwoven fabric was prepared by embossing into a lattice shape at a linear pressure of 30 kg with a roller at 140 ° C. The surface resistivity of this nonwoven fabric was 5.4 × 10 ⁸ Ω, which was excellent in conductivity.

[0021]

The olefin-based conductive conjugate fiber of the present invention is excellent in antistatic performance, has excellent adhesion to polyolefin, and can be produced more easily. Moreover, it can be handled in the same way as ordinary synthetic fibers, and is in the form of continuous filaments or staples.
In a non-crimped state or in a crimped state, it can be mixed with a nonwoven fabric of a polyolefin material by a known method, and antistatic properties can be imparted to a fiber product. Of course, it can be mixed with fiber products of materials other than polyolefin, and the mixing ratio to fiber products is usually about 0.1 to 5% by weight, and depending on the purpose, it is 5 to 1% by weight.
In some cases, a mixing ratio of less than 00% by weight or 0.1% by weight is applied.

[Brief description of the drawings]

FIG. 1 is a specific example of a composite structure of a conductive composite fiber of the present invention.

FIG. 2 is a specific example of a composite structure of the conductive composite fiber of the present invention.

FIG. 3 is a specific example of a composite structure of the conductive composite fiber of the present invention.

FIG. 4 is a specific example of a composite structure of the conductive composite fiber of the present invention.

FIG. 5 is a specific example of a composite structure of the conductive composite fiber of the present invention.

FIG. 6 is a comparative example of a composite structure of a conductive composite fiber used to show the superiority of the present invention.

[Explanation of symbols]

 1 Conductive component of conductive composite fiber 2 Protective component of conductive composite fiber (non-conductive component)

Claims (3)

(57) [Claims] 1. A conductive component comprising a polyamide or polyester composition containing conductive particles, and a protective component comprising a polyolefin obtained by melt-mixing at least a part of a modified polyolefin obtained by graft polymerization of an unsaturated carboxylic acid or a derivative thereof. A conductive composite fiber, wherein at least a part of the conductive component is composited so as to be exposed on the fiber surface. 2. The total amount of the unsaturated carboxylic acid or its derivative in the protective component is 0.1 to 1 with respect to the polyolefin.
The conductive conjugate fiber according to claim 1, which is 0% by weight. 3. An unsaturated carboxylic acid or a derivative thereof,
The conductive conjugate fiber according to claim 1, which is an unsaturated dicarboxylic acid or an anhydride thereof.