JPH03249212A - Electrically conductive conjugate fiber - Google Patents

Abstract

PURPOSE:To obtain the subject fiber having excellent electrical conductivity and whiteness by bonding an electrically conductive layer composed of a specific conductive particle and a thermoplastic polymer to a protecting layer composed of a fiber-forming polymer. CONSTITUTION:The objective fiber is composed of (A) an electrically conductive layer composed of (a) electrically conductive particles containing an inorganic compound as a nucleus covered with a metallic layer and having a coating layer of an electrically conductive metallic compound on the surface and (b) a thermoplastic polymer (preferably polyolefin, polyamide, polyester, etc., having a crystallinity of >=70%) and (B) a protecting layer composed of a fiber-forming polymer and bonded to the layer A. The metallic compound to form the coating film is preferably tin oxide, zinc oxide, indium oxide, copper iodide, etc.

Description

[Detailed description of the invention] (Technical field to which the invention pertains) The present invention relates to novel conductive fibers.

(Problems with the prior art and objects of the present invention) The conductive fibers are
Due to its excellent static electricity removal effect due to corona discharge,
It is mainly used in small amounts to impart antistatic properties to products such as fibers, various resins, and rubbers. Conventionally, composite fibers made of conductive polymers mixed with carbon black (carbon particles) and fiber-forming polymers have been used.
The composite fiber has problems in that it is black in color and has low HL conductivity, so that its antistatic ability is insufficient.

Furthermore, it has been proposed to use conductive polymers mixed with metal particles, but it is difficult to obtain particles small enough for fibers, and fine metal particles tend to aggregate and cannot be uniformly dispersed in the polymer. Because of this difficulty, conductive composite fibers that use metal particles have not yet been put into practical use.

The present inventors have developed conductive fibers using metal oxides (semiconductors) in Japanese Patent Publication No. 61-15284, No. 61-5633.
This was proposed in Publication No. 4. Conductive fibers made using metal oxide fine particles have the great feature of being able to obtain high whiteness, but their conductivity is lower than those made using carbon particles or metal particles, and their antistatic properties are therefore somewhat inferior. There is a drawback.

An object of the present invention is to provide a novel composite fiber that can be produced in a relatively compact manner and has excellent conductivity and/or white skin.

(Means and effects for solving the problem) The conductive conjugate fiber of the present invention is a conjugate fiber formed by bonding a conductive layer made of a mixture of conductive particles and a polymer and a protective layer made of a fiber-forming polymer. The conductive particles have an inorganic compound core, a metal layer on the outside, and a conductive metal compound film on the surface.

The conductive particles used in the present invention are new particles having a three-layer structure of an inorganic compound core, a metal layer, and a metal compound film. In general, it is extremely difficult to obtain metal particles with a size suitable for spinning, that is, a diameter of 0.05 to 1.5 μm, especially 0.1 to 1 μm, and with high uniformity. Things have not been put into practical use. Further, as mentioned above, metal fine particles have a high aggregation property, and it is extremely difficult to uniformly disperse them in a polymer.

Inorganic compounds such as titanium oxide, zinc oxide, tin pentoxide, alumina, silica, zeolite, mullite barium sulfate,
Particles such as calcium carbonate can be obtained in a size suitable for the above-mentioned spinning, and conductive particles having a two-layer structure can be produced by forming a metal layer on their surfaces. However, microparticles with a metal layer on their surface have extremely strong mutual affinity and cohesiveness, and it is often extremely difficult to mix and disperse them uniformly with polymers. They tend to easily sinter together into coarse particles. However, if the outside of the metal layer is covered with a film of a metal compound, the cohesiveness and sinterability can be significantly improved. Preferably, the metal compound used for this purpose is electrically conductive (conductor or semiconductor). In semiconductors, in order to increase conductivity, it is also preferable to add a small amount of an electron-donating or electron-accepting doping agent. Examples of doping agents include antimony oxide for tin oxide, aluminum oxide for zinc oxide, etc. I can do it. In addition, silver and copper oxides, copper iodide, copper sulfide, etc. themselves exhibit considerable electrical conductivity, and if the metal compound film is extremely thin, the decrease in electrical conductivity can be kept to a minimum (the tunnel effect also occurs). fully expected). From the standpoint of conductivity, the thinner the metal compound film on the surface, the better.
From the point of view of improving cohesion, the thicker the better. Therefore, the thickness of the metal compound film is preferably in the range of 1 to 0.2 μm, particularly preferably in the range of 0.002 to 0.1 μm, and
, o s to 0.05 μm is most preferred.

A metal compound film can be formed by depositing a metal compound on a metal layer by vapor deposition, ion blating, CVD, chemical reaction, etc., and is formed by reacting oxygen, iodine, etc. on the surface of the metal layer itself. You can also do that. In the latter case, the boundary between the metal layer and the metal compound is not necessarily clear, and a graded material structure may be formed in which the metal content gradually and continuously increases toward the inside. In such a case, when the metal content on the surface is X%, the metal content (%
The point where ) is (100x)/2 is regarded as the boundary between the metal layer and the metal compound film.

Conventionally, conductive composite fibers that utilize conductive particles with a conductive metal compound film formed on the surface of inorganic particles are well known (
(Special Publication No. 61-15184, etc.). However, such particles with a two-layer structure are inherently inferior in electrical conductivity compared to particles with a three-layer structure having an internal metal layer used in the present invention.

In the three-layer structure particles used in the present invention, the current passes vertically (the shortest distance) through the metal compound film on the surface to reach the metal layer, and conversely, the current passes vertically from the metal layer to the metal film on the other side of the particle. It passes through and flows to the next particle. Therefore, in three-layer structure particles, the distance that the current passes through the metal compound on the surface is minimal, and most of the current path is through the metal, so
Conductivity close to that of metal particles can be obtained. As mentioned above, with the conventional two-layer structure particles, the specific resistance of the particles (when compressed) was about I-10 Ωm, which was the limit that could be practically achieved, but with the three-layer structure particles used in the present invention, it was less than 1 Ωm, and compared to The target particle size is uniform, and a product with low agglomeration and high practicality can be obtained.

Examples of the compound forming the metal compound film include conductive (including semiconductor) metal oxides such as tin-zinc, copper, silver, indium, and zirconium, and conductive compounds such as copper iodide and copper sulfide. In particular, tin oxide, zinc pentoxide, indium # oxide, copper iodide, etc. are preferable for the purpose of the present invention because they can be colorless, white, or have a low degree of coloring.
Particularly preferred are those in which doping is added to improve conductivity.

The conductive particles are mixed with a thermoplastic polymer to form the conductive layer of the composite fiber. The thermoplastic polymer used in the present invention is not particularly limited, but useful examples include polyamide, polyester, polyurethane, polyolefin, polyether, polyacrylic, polyvinyl, polyimide, and polysulfide polymers. Polyolefins with particularly high crystallinity (50% or more, especially 70% or more).

Polyether, polyamide, polyester, polyvinyl, etc. are preferred from the viewpoint of electrical conductivity. The mixing ratio of the conductive particles should be within a range that exhibits sufficient fluidity in spinning processes such as melt spinning, dry spinning, and wet spinning, and that the resulting composite W4 miscellaneous has sufficiently high monoelectricity. The specific resistance of the conductive layer of the composite fiber must be 10' Ωcm or less, and 102 Ωcm
It is preferably 1 Ωcm or less, and most preferably 1 Ωcm or less. As mentioned above, the present invention can also provide a resistance of 1 Ωcm or less. The mixing ratio of conductive particles necessary to obtain such conductivity varies depending on the size (diameter) of the particles and the crystallinity of the polymer, but in most cases it is 50-80%, especially 60-80%.
It is about 75%.

The composite structure and composite ratio of the conductive layer and the protective layer are arbitrary.

The composite ratio is preferably in the range of 50150 to 1/99 in most cases, particularly preferably in the range of 75/25 to 2/9B.The composite structure may be arbitrary, such as parallel (side-by-side) type, core-sheath type, radial type, multiple type, or multilayer type. However, the one with the conductive layer exposed on the surface has better antistatic properties. However, since the exposed conductive layer can generally damage the opposing hand due to friction, it is preferable to minimize the exposed area.

Figure 1 is a cross-sectional view of three-layer conductive particles used in the present invention. In Figure 9, l is the core of the inorganic compound, 2 is the metal layer, and 3 is the conductive metal compound film. The diameter D1 is preferably 0.05 to 1.5 μm, particularly 0.1 to 1 μm. The diameter D2 of the nucleus is preferably about 0.2 to 0.95 times, particularly about 0.3 to 0.9 times, Dl. The thickness (or maximum thickness) of the metal layer TI is 0.005 to 0.2 p
m, particularly preferably about 0.01 to 0.18. The thickness T2 of the metal compound film is 0. OOI ~0.2pm
A range of 0.002 to 0.018 m is particularly preferred.

FIGS. 2 to 11 are cross-sectional views of composite fibers showing examples of composite structures that can be used in the present invention. In the figure, 4 indicates a conductive layer, and 5 indicates a protective layer.

Figure 2 is an example of parallel type, Figure 3 is an example of multiplexed parallel type,
Figure 4 is an example of a three-layer type, Figure 5 is an example of a radial type, Figure 6 is an example of a core-sheath type, Figure 7 is an example of a core-sheath type which is the opposite of Figure 6, and Figure 8 is an example of a multilayer type. FIG. 9 shows an example of a core type, FIG. 9 shows an example of a multiple core/sheath type, FIG. 10 shows an example of a keyhole type, FIG. 11 shows an example of a multiplexed keyhole type, and FIG. 12 shows an example of a multilayer type.

Although the figure shows an example of a circular cross-section, any cross-sectional shape of synthetic fibers such as non-circular, oval, triangular, star-shaped, etc. can be applied.

Composite fibers can be spun by conventional melting, dry, wet, and other spinning methods. For example, a method of melting or spinning a molten conductive component and a protective component in a spinneret, removing the material, and subjecting it to stretching, heat treatment, etc. if necessary, or spinning at high speed, or spinning and stretching at the same time. Methods are also useful. In addition, the conductive layer polymer is made of a low melting point and highly crystalline material such as polyolefin, the protective layer polymer is made of a high melting point material, and fibers obtained by stretching and/or heat treatment at a temperature between the melting points of both. It is possible to maintain high conductivity.

Hereinafter, preferred embodiments of the present invention will be summarized and described.

(2) The composite fiber according to the claims, wherein the metal compound coating of the conductive particles is selected from the group of metal oxides, metal sulfides, and metal iodides.

(3) The metal layer of the conductive particles is one or two selected from the group of silver, gold, copper, nickel, chromium, and indium.
A conjugate fiber according to the claims, which is composed of at least one metal.

(4) The average diameter of the conductive particles is 0.05 to 1.5μ
m, the average thickness of the metal layer is 0.005 to 0.2 μm, and the average thickness of the metal compound film is 0. The composite fiber according to claim 1, wherein the OO is in the range of 1 to 0.2 μm.

+5) The composite fiber according to the claims, wherein the conductive particles have a specific resistance of 10 2 Ω·cm or less.

(6) Claims in which the fiber-forming polymer is one or more polymers selected from the group of polyamides, polyesters, polyolefins, polyacrylics, polyvinyls, polyethers, polyimides, and polysulfides. Composite fibers as described.

(7) The thermoplastic polymer forming the conductive layer is one or more polymers selected from the group of polyamide, polyester, polyolefin, polyether, polyacrylic, polyvinyl, polyimide, and polysulfide. Composite fiber according to the claims.

(Example) Example 1 A silver layer with a thickness of about 0.02 μm was formed on the surface of titanium oxide particles with a diameter of 0.2 μm by an ion-blating method, and on top of that, 7% by weight of oxide was added as a doping agent. Conductive particles P are coated with tin oxide containing antimony using the same ion blating method to a thickness of about 0,008 μm.
I got 1. When particles PL were observed using EPMA, it was found that silver and tin oxide layers were uniformly formed on the surfaces of the particles. Also,
The specific resistance of the powder when compressed (30 kg/cm”) is 0.01
2 Ωcm, and the average diameter was 0.27 μm. 175 parts of particle P, 23 parts of high-density polyethylene with a molecular weight of 30,000 (melting point 125°C, crystallinity 90%), and 2 parts of magnesium stearate were melt-mixed to make a conductive material. Polymer CPI was obtained. cpi as the conductive component, molecular weight 2200
Using 0 nylon 6 as a protective component, both were melt-spun into a core-sheath type as shown in FIG. After spinning at a speed of 600 m/min, cooling and oiling, the resultant was stretched 3.1 times at 150° C. to obtain a 20 denier/3 filament conductive yarn CYI.

The specific resistance of the conductive layer of CYI is 0.76 Ωcm, which is 10
It showed excellent conductivity of Ωcm or less.

Comparative Example A silver film having a thickness of about 0.05 μm was formed on the surface of titanium oxide particles having a diameter of 0.2 μm by an ion blasting method to obtain St particles P2. Conductive particles P3 were similarly coated with tin oxide containing 7% by weight of antimony oxide to a thickness of approximately 0.02 μm. When particles P2 and 3 were observed using EPMA, the surfaces of the particles contained silver and tin oxide. The film was formed uniformly. Moreover, particle P2. When compressing P3
30kg/cm") powder specific resistance is 0.02.5.
8Ωcm, and the average particle size is 0.29.0.26/7
It was m.

Particles P2 and P3 were melt-mixed in the same manner as in Example 1 to form conductive polymer CP2 (particle P2 was 800% by weight).
(containing), CF2 (particle P3 containing 755% by weight) was produced, and melt composite spinning was further performed in the same manner as in Example 1. When polymer CP2 was used, the filter and orifice of the spinneret were clogged, making spinning impossible. this is,
This is because the surface layer of the particles P2 is coated with silver, so the particles agglomerate and sinter under high temperature and high pressure conditions such as cross-firing and spinning, resulting in coarsening. The undrawn composite fiber yarn obtained using polymer CP3 was further drawn 3.1 times at 150°C to
The conductive yarn CY3 was made of denier/3 filament. C.Y.
The specific resistance of the conductive layer of No. 3 was 2.7×10′Ωcm, which was inferior to the CYI yarn in conductivity.

Example 2 A copper film with a thickness of about 0.02 μm was formed on the surface of titanium oxide particles with a diameter of 0.25 μm by an ion-blating method, and on top of that, zinc oxide containing 5% by weight of aluminum oxide was also ionized. The conductive particles P4 were coated with a thickness of about 0.007 μm by a brating method. Rf
When the t-type particles P4 were observed by EPMA, copper and zinc oxide layers were uniformly formed on the surfaces of the particles. Also,
The specific resistance of the powder when compressed (30 kg/cm”) is 0.07
Ωcm, and the average diameter was 0.31 μm.

Particles P4 were mixed with the polyethylene of Example 1 at 75% by weight to obtain conductive polymer CP4. Polymer CPI and C
F4 is the conductive component, nylon 6 with a molecular weight of 22,000 is the protective component, and both are melted at a composite ratio (conductive component/protective component volume ratio) of 1/10 to form a partially exposed keyhole-shaped structure where the conductive component scratches the fiber surface. Combined, diameter 0.25 mm
, spun from an orifice at 278°C, 60°C after oiling.
It was wound at 0 m/min and stretched 3.2 times at 150°C to form a 20 denier/3 filament alii&cY4. Obtained CY5. Thread CY4. The specific resistance of the conductive layer of CY5 is 0.
．． It was 76.1.02 Ωcm.

Thread CY1. CY3. CY4. CY5 and nylon 6 drawn yarn (2600 denier/144 filament)
The combined yarn is used for one of the four courses, and the other three courses are made of tufted carbent (loop pile) using nylon 6-wrap yarn (2600 denier/144 filament). ) was manufactured. Table 1 shows the electrostatic potential of the human body measured when walking on the obtained carpet with leather shoes (25° C., 20% RH). For comparison, the voltage charged on the human body when walking on a carpet made of only Nanlon 6-wrap yarn is also shown.

The first thread CYI, CY4. The human body charge voltage for both CY5 and Nylon 6
The antistatic property was lower than that of the antistatic property. CY3
The lack of antistatic performance is due to the conductivity of cyl, CY4. This is because it is inferior to CY5. Also, CYl is CY4. The reason why the antistatic property is inferior to that of CY5 is that since the conductive layer is not exposed on the fiber surface, corona discharge may occur and the charge cannot be diffused or dissipated quickly.

Example 3 The conductive polymer CPI of Example 1 was used as a conductive component and polyethylene terephthalate with a molecular weight of 18.000 was used as a protective component at a composite ratio of 1/9 to form a cross section as shown in Figure 7, with a diameter of 0.25 mm. .

Spun from an orifice at 278°C and oiled at 150°C.
The yarn was wound up at a speed of 0 m/min and stretched 3.3 times at 150° C. to obtain a drawn yarn CY6 of 30 denier/3 filaments. The specific resistance of the yarn CY6 was 0.82 Ωcm, indicating good conductivity.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a three-layer structure conductive particle used in the present invention, and FIGS. 2 to 12 are specific examples of cross-sections of the composite fiber of the present invention. In the figure, 1 indicates a core of an inorganic compound, 2 a metal layer, 3 a conductive metal compound film, 4 a conductive layer, and 5 a protective layer.

Claims (1)

[Claims] In a composite fiber in which a conductive layer made of conductive particles and a thermoplastic polymer is bonded to a protective layer made of a fiber-forming polymer, the conductive particles have an inorganic compound as a core, a metal layer on the outside, and a surface. A conductive composite fiber characterized by having a conductive metal compound film.