JP2633067B2 - Conductive composite fiber - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a conductive fiber. More specifically, the present invention relates to a conductive conjugate fiber having an excellent color tone and having a small decrease in conductivity due to stretching during a fiber product process.

(Prior art) Conventionally, a method has been used in which conductive fibers are mixed in a carpet pile to prevent electrostatic charging of a human body on a carpet at low humidity, and a conductive carbon black or an inorganic conductive material other than carbon black is used. A conductive composite fiber in which a conductive polymer in which conductive particles, for example, metal compound particles are mixed, and a normal nonconductive polymer are bonded is known.
The mixing of conductive fibers into the carpet pile is carried out by blending, twisting, or blending the conductive fibers for non-conductive carpet pile with conductive fibers. However, there is a disadvantage that the cost is high.

In recent years, as a simple method of mixing, an undrawn yarn of conductive conjugate fiber is introduced into the cooling chimney of the melt-spinning process of non-conductive carpet raw fiber, and it is aligned on a tension roll simultaneously with the raw fiber filament for carpet pile, and then Stretching and bulking have been performed to obtain raw fibers for carpet pile containing conductive fibers. In this case, the drawing step is often performed at room temperature, and usually, as the conductive fiber, a conductive conjugate fiber using a conductive polymer containing conductive carbon black containing a small decrease in conductivity even when cold drawn is used. Have been.

(Problems to be Solved by the Invention) However, since the carbon black-containing polymer is black, the fiber tends to exhibit black. Especially when the conductive component is exposed on the fiber surface in order to obtain sufficient antistatic performance,
A major drawback is that the appearance of the fibers is significantly impaired. On the other hand, as a white conductive composite fiber, a conductive composite fiber using a conductive polymer in which conductive metal oxide particles are mixed with a thermoplastic polymer such as nylon 6 or polyethylene is used. When a large amount of particles are mixed with a polymer (for example, 50% by weight or more, particularly 70% by weight or more), conductivity is developed. The phenomenon that the conductivity decreases or disappears is remarkable. For example, normal stretching ratio 3.
Under spinning conditions such that excellent fiber performance can be obtained at about 5 times, when stretched 2.0 times or more at room temperature, the conductivity tends to be lost.

As described above, in reality, cold-drawable white conductive fibers have not yet been obtained.

SUMMARY OF THE INVENTION An object of the present invention is to provide a white conductive composite fiber which has a small decrease in conductivity even when cold drawn.

(Means for Solving the Problems) That is, the present invention provides a conductive component comprising a thermoplastic polymer containing 70 to 95% by weight of titanium oxide particles having a conductive tin oxide particle and / or a conductive tin oxide film. And a protective component comprising a fiber-forming polymer are bonded to each other, and the thermoplastic polymer of the conductive component is an α-polyolefin-based polymer having 4 to 10 carbon atoms such as polybutene-1, polypentene-1, and the like. The conductive fiber is one or more selected from the group of polymers.

The conductive particles used in the present invention are conductive tin oxide and / or titanium oxide coated with conductive tin oxide.

Many metal oxides such as tin oxide, zinc oxide, copper oxide, cuprous oxide, indium oxide, zirconium oxide, and tungsten oxide are often semiconductors close to insulators. However, the conductivity can be enhanced by, for example, adding a suitable second component (impurity) to the metal oxide in a small amount, usually 50% or less, often 25% or less. Examples of such a conductivity enhancer include antimony oxide against tin oxide, aluminum against zinc oxide,
There are metal oxides such as isodium, germanium, and tin. In the present invention, conductive tin oxide which has excellent conductivity and is commercially produced using antimony oxide as a conductive reinforcing agent is used. Further, particles in which a conductive film of the conductive tin oxide is formed on the surface of titanium oxide can also be used.

The conductivity of the conductive particles is such that the specific resistance in powder form is 10 ⁴ Ω
m or less, especially about 10 ² Ωcm or less, preferably 10 ¹ Ω
-Most preferably about cm or less. Actually, a ^{value of} about 10 ² to 10 ⁰ Ω · cm is obtained, and it can be suitably applied to the object of the present invention.

In addition, 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 flow diameter of 1 μm or less, particularly 0.5 μm or less, most preferably 0.3 μm or less are used.

The mixing ratio of the conductive particles to the conductive component is, in many cases, in the range of about 70 to 95% by weight, particularly preferably 80 to 90% by weight, in order to suppress a decrease in conductivity due to stretching.
If it is less than 70% by weight, conductivity is not exhibited due to low particle concentration, and even if the film is not stretched and shows conductivity, the conductivity is significantly reduced by stretching. On the other hand, if the content exceeds 95% by weight, it becomes difficult to uniformly disperse the white conductive particles in the polymer, and even if it can be dispersed with a great effort, the fluidity of the polymer is reduced, and the spinning is hindered. It is not preferable.

The specific resistance (volume resistivity) of the conductive component needs to be less than 10 ⁵ Ω · cm, preferably 10 ⁴ Ω · cm or less.
0 ² Ω · cm or less is particularly preferred. Further, the conductive component is preferably an apparently drawn filament and has a specific resistance of less than 10 ⁴ Ω · cm, more preferably 10 ² Ω · cm or less, and particularly preferably 10 ¹ Ω · cm or less.

In the present invention, a thermoplastic polymer that forms a conductive component by mixing with conductive particles is important. That is,
It is important to use one or more selected from the group consisting of α-olefin polymers having 4 to 10 carbon atoms such as polybutene-1 and polypentene-1 and copolymers thereof. For olefin-based polymers such as polyethylene and polypropylene, and polyamide-based and polyester-based polymers, if a large amount of conductive particles is mixed, the flexibility becomes poor and the conductive components break when stretched at room temperature (hereinafter referred to as cold stretching). And the conductivity tends to be significantly reduced. On the other hand, the polymer proposed in the present invention can maintain a certain degree of conductivity even though it is cold drawn, although its conductivity is slightly lowered. Further, it has a feature that conductivity can be restored by a heat treatment in a dyeing process of a fiber product such as a carpet. The reason why the conductive structure of the conductive component composed of the polymer is not destroyed by cold stretching is unknown, but the polymer is a polymer in which particles are not mixed even if conductive particles are mixed to the extent that conductivity is developed. Since the physical properties can be maintained, even if the composite fiber is cold-drawn in a state where the composite fiber is formed, unlike the conventional conductive component composed of nylon 6 or polyethylene, the conductive particles are simultaneously formed with the matrix polymer. It is presumed that the film is stretched, the distance between particles is slightly increased, and the conductivity is reduced, but the property that the conductive component itself is not cut and can be recovered by heat treatment after stretching is exhibited.

If necessary, the conductive component may include dispersibility (eg, waxes, polyalkylene oxides, various surfactants, organic electrolytes, etc.), colorants, pigments, stabilizers (antioxidants, ultraviolet absorbers, etc.). , A fluidity improver, and various other known additives.

On the other hand, as the fiber-forming protective component, any material that can be spun and cold drawn can be used. Among them, polyamides such as nylon 6, nylon 66, nylon 12, and nylon 610,
And copolymers and modified products thereof, and polyolefins such as polyethylene and polypropylene. Matting agents, pigments, coloring amount,
Known additives such as stabilizers and antistatic agents (polyalkylene oxides, various surfactants, etc.) can be added as necessary.

The composite shape of the conductive component and the protective component is arbitrary. For example, a type in which the conductive component is slightly exposed on the fiber surface as shown in FIG. 1 and a non-exposed core-sheath type as shown in FIG. 2 can be used. It is more preferable that the acidic component is exposed on the fiber surface. The composite ratio is not limited, but in many cases, the composite ratio (cross-sectional area) of the conductive component is preferably about 3 to 60%.

(Action and Effect of the Invention) According to the present invention, a fiber having a small decrease in conductivity even when drawn at room temperature (cold drawing) and having excellent antistatic performance in a white paper can be easily obtained by a normal spinning method. be able to. Further, the conductive conjugate fiber of the present invention does not require a special mixing step, and a bulky processed yarn for carpet pile or a yarn for woven or knitted material containing white conductive fiber can be easily obtained by a usual method, It is extremely useful in the production of conductive textiles.

(Examples) Hereinafter, the present invention will be described with reference to examples. % Indicates a weight ratio unless otherwise specified.

Example 1 A titanium oxide particle having a tin oxide film of 15% on its surface mixed with 1.5% antimony oxide and fired to obtain a light gray blue conductive material having an average particle size of 0.25μm and a specific resistance of 4.0Ωcm. Let the powder be A1.

Mitsui Petrochemical Polybutene-1 (Type M2481, Melting Point 80
CP1), and a polymer in which 1.5% of titanium oxide particles are dispersed as a matting agent in nylon 6 having a molecular weight of about 16,000 and a melting point of 215 ° C is referred to as NP1. I do.

Using CP1 as a conductive component and NP1 as a protective component, composite melt spinning was performed at a cross-sectional shape and a composite ratio (volume ratio of conductive component / protective component) of 1/10 as shown in FIG.

The melt-combined two components are spun from a 0.25 mm diameter orifice at a spinning temperature of 280 ° C, and cooled and oiled for 800 m.
/ min. at a speed of 60 / den. to obtain an undrawn yarn UY1 of 60 denier / 3 filaments. Next, the undrawn yarn UY1 is drawn at room temperature to a draw ratio of 3.0, and the drawn yarn Y1 of 20 denier / 3 filaments is drawn.
I got

When the specific resistances of the yarns UY1 and Y1 were measured, they were 3.5 × 10 ³ ,
6.9 × 10 ⁴ Ω · cm, and there was little decrease in conductivity due to stretching.

The drawn yarn Y1 was heat-treated under a load of 0.002 g / d with hot water of various temperatures for 1 minute. Table 1 shows the results.

As shown in the table, the conductivity was restored by heat treatment with hot water of 60 ° C. or higher.

Comparative Example 1 CP2 is a conductive polymer obtained by mixing 75% by weight of the conductive powder A1 of Example 1 with low-density polyethylene having a molecular weight of 50,000 and a melting point of 102 ° C. Using CP2 as a conductive component and NP1 as a protective component, composite spinning and drawing were performed in the same manner as in Example 1, and undrawn yarn UY
2. A drawn yarn Y2 was obtained. The specific resistance of yarn UY2, Y2 is 5.4 × 1 each
0 ³ , 5.8 × 10 ⁷ Ω · cm, and the conductivity was remarkably reduced by stretching. Further, the yarn Y2 was heat-treated for 1 minute in hot water of about 98 ° C., but the specific resistance was 4.7 × 10 ⁷ Ω · cm, and the conductivity did not recover.

[Brief description of the drawings]

1 to 4 are examples showing the cross-sectional shapes of conductive conjugate fibers suitable for the present invention. (A) shows a conductive polymer containing a metal compound, and (B) shows a fiber-forming polymer.

Claims (1)

(57) [Claims] 1. A conductive component comprising a thermoplastic polymer containing 70 to 95% by weight of conductive tin oxide particles and / or titanium oxide particles having a coating of conductive tin oxide, and a protective component comprising a fiber-forming polymer. Wherein the thermoplastic polymer of the conductive component is selected from the group consisting of α-polyolefin polymers having 4 to 10 carbon atoms such as polybutene-1 and polypentene-1 and copolymers thereof. Or 2
A conductive fiber, which is at least one kind.