JPH02289118A - Electrically conductive white conjugate fiber - Google Patents

Abstract

PURPOSE:To provide the subject antistatic conjugate fiber having excellent fiber properties and wearing durability and composed of a non-conductive component consisting of a fiber-forming thermoplastic polymer and an electrically conductive layer component produced by mixing electrically conductive metal oxide particles and a thermoplastic elastomer. CONSTITUTION:The objective conjugate fiber is produced by joining (A) a sheath component consisting of a non-conductive component composed of a fiber- forming thermoplastic polymer and (B) a core component consisting of an electrically conductive layer composed of a mixture of (i) 50-90wt.% of electrically conductive metal oxide particles (e.g. produced by coating the surface of titanium oxide particle with an electrically conductive coating layer composed mainly of zinc oxide or tin oxide) and (ii) a thermoplastic elastomer (e.g. composed of a hard segment and a soft segment).

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Industrial Application Field The present invention relates to a conductive composite rutted fabric that is concerned about its static elimination performance, and in particular to a conductive composite fiber that has excellent static elimination performance with excellent fiber properties and wearing durability. It is.

More specifically, the fiber-forming polymer is used as a non-conductive layer component (A
), and the white colored composite fiber is a colorless composite fiber that is characterized by static elimination performance that uses a thermoplastic polymer containing a conductive metal oxide as the conductive layer component (B). 0.01 wtchi~l Q wtchi (wt%
) This invention relates to conductive composite fibers that can be used to obtain compositions such as cloths having excellent static elimination performance just by adding the present invention, and whose static elimination performance does not deteriorate even after one year of actual use.

(2) Conventional technology Various proposals have been made for conductive fibers that have excellent static elimination performance.For example, there have been proposals to impart conductivity by plating the surface of non-conductive fibers with metal. There are also those in which a conductive coating layer is formed by dispersing conductive carbon black in a resin and then coating the fiber surface with the dispersion. However, these materials are obtained through complicated manufacturing processes and technically difficult methods, or during preparatory steps for putting conductive fibers into practical use, such as chemical treatment during the scouring process for weaving and knitting, or during actual use. There is a problem in that the conductivity easily decreases due to external effects such as wear during use and repeated washing, making it beyond the scope of practical use. As other conductive materials, metal fibers such as steel fibers are known to have excellent static elimination performance.

Metallic fibers are not compatible with general organic materials, resulting in poor spinning properties, causing problems in the weaving and dyeing finishing processes, and easily breaking or falling off when washed when worn, and due to their electrical conductivity. This caused problems such as electric shock and sparks, or melting of the fabric. In order to solve these problems even to some extent, conductive composite fibers have been proposed in which a conductive layer component made of a polymer mixed with conductive carbon black and a protective component made of a fiber-forming polymer are bonded together.

However, a major drawback of conductive composite fibers using carbon black is that the fibers are colored black, which limits their uses.

As a method to solve this drawback, conductive composite fibers using white or colorless conductive metal oxide particles have recently been proposed.

(3) Problems to be Solved by the Invention For example, as described in Japanese Patent Publication No. 58-39175, 3 wtql to 20 wt titanium oxide particles having a stannic oxide coating are dispersed in a synthetic polymer. Electrically conductive synthetic polymer compositions have been proposed. However, in this case, due to the following two reasons, υ conductive composite #I that has the static elimination performance that we are aiming for! It is difficult to obtain support.

a. Many metal oxides are semiconductors that are close to insulators, and in order to obtain a conductive fabric with static elimination performance, it is necessary to add a doping agent to the metal oxide. do.

b. At the low particle mixing ratio described, it is difficult to obtain the desired conductive composite fiber.

Due to the above two problems, it is not possible to obtain a practically useful conductive composite fiber according to the present invention. According to the study results of the present inventors, the blending amount of the conductive metal oxide needs to be at least 55 wt%, and preferably cio
JP-A-57-6762, which features wt4 or higher,
In Japanese Patent Publication No. 62-29526, a mixture of a conductive metal oxide and a thermoplastic resin (conductive layer) and a fiber-forming heat c.
In the case of producing an electrically conductive conjugate fiber made of an IR polymer, a method has been proposed in which the conductive layer is repaired by further heat-treating the fiber after producing a composite yarn and drawing the fiber. When a thermoplastic resin is used as the binder for the conductive metal oxide, the conductive layer is cut during the stretching process. In this state, conductivity has been lost and it cannot function as an anti-static fJIM. Such heat treatment is necessary when a thermoplastic resin, particularly a highly crystalline thermoplastic resin, is used as the binder for the conductive metal oxide. The antistatic fiber obtained in the above patent has the drawback of poor production efficiency due to the presence of a heat treatment process after drawing, and the control achieved! #M also has a major drawback of lacking durability.

That is, in Japanese Patent Publication No. 62-29526, thermoplastic resins with a high degree of crystallinity are cited as suitable thermoplastic resins as binders for conductive metal oxides, with the condition that the composite fibers are heat-treated after drawing.

The crystallinity of the thermoplastic resin is preferably 40% or more, and specifically polyethylene, polyethylene oxide, and nylon 6 are used.

One method for obtaining conductive composite fibers is to use a thermoplastic resin with a high degree of crystallinity as a binder for conductive metal oxides and heat-treat the composite fibers after drawing them. The resulting conductive composite fiber had a problem in that it lacked durability when worn.

As is well known, anti-static performance refers to the ability to remove the electric charge from a charged object by non-contact.As a result of intensive study by the present inventors, the resistance of the filament (hereinafter also referred to as core resistance) is
If it is less than Xl011Ω/tan・f, a nonequilibrium electrolyte is formed and the static electricity is removed by corona discharge, but the core resistance is I
0'' Q151-f or more, static elimination does not occur due to the corona discharge voltage, and it does not exhibit effective antistatic properties.For these reasons, antistatic fibers (thickness #I with static elimination performance) are is not dependent on the conditions of use of the fiber, and must always be less than 9 x 10'' Ω/, -f.

The durability of antistatic fibers refers to the durability of antistatic fibers, for example, in antistatic clothing, when a fabric woven with antistatic fibers at O, l wt% - IQ wt% is worn for one year, and the antistatic performance is determined at that time. Determine whether or not to do so. The standard value for the amount of charge in the static electricity safety guidelines published by the Ministry of Labor's Occupational Safety Research Institute is 7μ coulombs/♂, and it is necessary that the amount be less than this value. Conventional white or colorless conductive composite fibers could not satisfy the above durability. For example, when the thermoplastic polymer is polyethylene, the durability of actual wear is insufficient, and the inventors have found that it is particularly unsuitable for use in dangerous work such as work clothes. . When a crystalline thermoplastic resin is used as the thermoplastic polymer, the resistance of the filament immediately after the preparation of the conductive composite fiber can be reduced to a value of 9 x 10"Ω/cM-f or less, and the electrification of the fabric can be reduced. Although the standard value can be satisfied, the antistatic performance of the fabric deteriorates due to poor durability, making it difficult to use in practice.Durability is poor when using crystalline thermoplastic resin. The reason why it does not draw is that the crystalline thermoplastic resin is brittle and the conductive structure of the antistatic fiber is easily broken.

(4) Means for Solving the Problems The present inventors conducted detailed studies in order to provide a conductive composite fiber free of such drawbacks. As a result of extensive research into the fiber structure, static elimination performance, and durability in practical use, we have discovered a white or colorless conductive composite fiber that has excellent static neutralization performance and durability in practical use, and have arrived at the present invention. be.

The gist of the present invention is a conductive composite comprising a fiber-forming thermoplastic polymer as a non-conductive component (B) and a mixture of conductive metal oxide particles and a thermoplastic resin as a conductive component (B). It is a white or colorless conductive composite fiber characterized in that the thermoplastic resin used for the core conductive component is a thermoplastic elastomer. The nine conductive composite fibers produced under these conditions had a filament resistance of 9 x 10100/F or less and excellent durability for actual use.

The most important issue when obtaining white or colorless antistatic fibers is that the conductive layer often breaks during the drawing process of composite fibers, but how to solve this problem and how durable it is when actually worn. There are two points: how to assign gender. The method of using a crystalline thermoplastic resin tube as a binder and applying heat treatment after stretching the fiber is a useful method for rebonding the conductive layer cut by the stretching process; According to the study results of the present inventors, the conductive composite fibers lacked durability in actual use.

The reason for the lack of durability is that if a thermoplastic resin, especially a crystalline thermoplastic resin, is not used as a binder, the broken conductive layer can be repaired by heat treatment, but the conductive layer itself is This is because the conductive layer is physically brittle and will break again during repeated expansion and contraction during actual wear, making it impossible to demonstrate durability.

As a result of extensive studies, the present inventors recognized that a conductive composite fiber whose conductive layer is a mixture of conductive metal oxide particles and a thermoplastic elastomer has a low resistance value and high durability against actual use. It was completed. Furthermore, the conductive conjugate fibers obtained in the present invention are useful because they do not require a step of heat treatment after drawing the fibers, and the process can be simplified.

A thermoplastic elastomer is a polymeric material that is a rubber elastic body at room temperature, but can be plasticized and molded at high temperatures (temperature range above the melting point). -The thermoplastic elastomer in the shell is divided into the following two types.

1. Composed of amorphous molecular chains that easily undergo molecular rotation (referred to as soft segments) and highly crystalline resin molecular chains (referred to as . . . -d segments). Portions of the soft segment are constrained by portions of the node segment.

2. The basic skeleton is constrained by soft segments, but is also constrained by ionic crosslinks (dissociated by heat but recombined at low temperatures) K. As a thermoplastic elastomer with such a structure, carboxylate poly ff
-, tertiary amine pendant) NBR, etc.

As the thermoplastic elastomer used in the present invention, any of the above-mentioned thermoplastic elastomers can be used. The thermoplastic elastomer used in Kinoe M has rubber elasticity and has a tensile elongation at break (JIS K-6301) of 100- or more, preferably 200- or more. is good.

In the present invention, it is preferable to use a thermoplastic elastomer composed of a hard segment and a soft segment as the thermoplastic elastomer. When this material is used as a binder for conductive metal oxide particles, conductive conjugate fibers having low resistance and high wear durability can be obtained.

Thermoplastic elastomers used in the present invention include hydrogenated products of 5BS (polystyrene, polybutadiene, polystyrene block copolymer) and SBS,
IS (polystyrene, polyimprene, polystyrene block copolymer) and hydrogenated products of SIS, SI (polystyrene.

Hydrogenated products of polyimblene block copolymer) and SI, polyurethane thermoplastic elastomer, polyester thermoplastic elastomer, polyamide thermoplastic elastomer, sulfonated ethylene propylene rubber, EP
Examples include DM, tertiary amine pendant NBR, and the like.

As the fiber-forming polymer forming the non-conductive layer of the conductive composite fiber of the present invention, any polymeric material that can be melt-spun may be used. For example, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6 and nylon 66, and polyolefins such as polyethylene and polypropylene are used. A thermoplastic polymer which is preferably used to form the non-conductive layer includes polyester-based poly-1-, which has polyethylene terephthalate and polybutylene terephthalate as main components. This polymer gold used is extremely durable when processed.

Improves durability when actually worn.

When using polyethylene terephthalate,
The heat resistance (heat decomposition resistance) required for thermoplastic elastomers is 300°C or higher. Thermoplastic elastomers suitably used under such conditions include hydrogenated products of SIS, hydrogenated products of Sl, hydrogenated products of SBS,
Polyester thermoplastic elastomer Examples include polyamide thermoplastic elastomer.

Examples of the conductive metal oxide particles used in the present invention include tin oxide, zinc oxide, silver oxide, steel oxide, cadmium oxide, and lead oxide.

Many metal oxides are semiconductors that are close to insulators.

However, the conductivity can be improved by adding an appropriate second component. Such conductivity enhancers (so-called doping agents) include oxides of different metals, and metals of the same or different types. For example, antimony oxide is added to tin oxide. Copper is added to copper oxide, aluminum oxide is added to zinc oxide, and tin or antimony is added to tin oxide and antimony oxide. The amount of doping agent added is determined by the electrical conductivity of the conductive metal oxide particles and the degree of coloring of the particles. That is, when the amount of doping agent added is increased to improve the electrical conductivity of the particles, although the electrical conductivity increases, the degree of coloring of the conductive particles increases.

In order to solve this problem, a method of increasing the electrical conductivity of conductive metal oxide particles while maintaining their white state has been explored, and one method is to change the surface of white metal oxide particles to It is covered with a film. That is, titanium oxide particles whose surface is mainly composed of zinc oxide or tin oxide and which uses antimony oxide as a doping agent are commercially available from various companies (for example, Mitsubishi Metals W-1, Titanium Industries ECT-52, etc.). 1 It is also preferable to use these in the present invention.

In order to prevent the particles from being colored, it is also useful to set the particle size of the conductive particles to a size K that is equal to or smaller than the wavelength of light.

Specifically, the particle size is 0.1 μm or less, preferably 0.05 μm or less.
By making the particle size less than μm, transparency can be imparted to the particles. In the present invention, such transparent conductive metal oxide particles may be used.

As the conductive particles preferably used in the present invention, it is preferable to use particles having an average particle diameter of 1 to 0.01 .mu.m, since the electrical conductivity can be increased.

In order to increase the electrical conductivity of the mixture, the conductive metal oxide particles must be brought into contact with each other.

For this purpose, it is important to increase the concentration of the conductive metal oxide in the mixture and to cause aggregation of the conductive metal oxide particles.

In general, a flexible or fluid polymeric material such as a silicone elastomer or a liquid elastomer is used as the binder, and in some cases, the amount of conductive metal oxide particles mixed can be extremely high. According to the study results of the present inventors, when such a polymer material is used, the mixed amount of conductive metal oxide particles is 80 to 90 W.
It can be raised up to about tj. However, in this case, although it is possible to increase the amount of conductive metal oxide particles mixed, it is difficult to increase the electrical conductivity of the mixture. For these reasons, it is not possible to obtain conductive composite fibers with low resistance even if a polymer material with high fluidity is simply used as a binder and the amount of conductive metal oxide particles mixed is increased. When using the binder of the present invention, in particular a thermoplastic elastomer with soft and hard segments, a high mixing ratio and moderate agglomeration occur, making it possible to avoid the above-mentioned disadvantages.

In the present invention, the mixing ratio of the conductive metal oxide particles and the thermoplastic elastomer is preferably such that the proportion of the conductive metal oxide particles in the conductive mixture is 50 to 90 wt%. The content is preferably 60 to 85 wt%, particularly preferably 70 to 80 wt%. Conventionally,
In the case of crystalline thermoplastic resins that have been proposed as binders for conductive metal oxide particles, further improvement in conductivity is not observed when the amount of metal oxide particles mixed exceeds 70 wt%. First, the fluidity of the conductive component of the conductive composite fiber is significantly reduced, resulting in extremely poor spinnability, and in particular, the life of the pack is significantly shortened due to filter clogging, and process stability is lost. However, it has been possible to overcome these drawbacks in some cases by using thermoplastic elastomers.

In the present invention, when creating a composite of a thermoplastic elastomer and conductive metal oxide particles, a surface treatment agent for the conductive metal oxide particles may be added.

Furthermore, a fluidity improver, a dispersant, etc. may be mixed.

Conductive composite of the present invention lI! For the male fiber, the usual manufacturing method for composite fibers can be used as is. That is, it may be a drawn yarn obtained by drawing the original yarn of the composite fiber, or by performing high-speed spinning, a highly oriented undrawn conductive composite fiber can be directly obtained by omitting the drawing step.

The composite form of the conductive composite fiber in the present invention can be of any type. Typical forms of the conductive composite fiber in the present invention are shown in FIGS. 1 to 5. Figure 1 shows a single-core conductive composite fiber, Figure 2 shows a multi-core conductive composite fiber M, Figure 3 shows a side-by-side type, Figure 4 shows a multiple side-by-side type, and Figure 5 shows a three-layer type. . The most preferred form of the present invention is a core-sheath structure. Either single-core or multi-core is fine.

When the white conductive fiber of the present invention is used for antistatic cloth, it is usually
It is the same as the case of ordinary conductive fibers that it is mixed into the cloth in an amount of 0.1 wt4 to 1 Q wt%. Naturally, these fabrics are completed through a dyeing and finishing process. Since the conductive layer component contains a large amount of conductive metal oxide particles, it is brittle and easily damaged by hot waste during processing. In particular, for fabrics mainly made of polyethylene terephthalate, high-temperature dyeing and high-temperature setting are unavoidable, and these processes can significantly affect the conductive layer components of conductive composite fibers. Ta.

In order to avoid being affected by high-temperature dyeing and high-temperature setting, a composite conductive fiber with a core-sheath structure was the most unaffected by the process.

The present invention will be explained in more detail with reference to Examples below.

Example 1 Titanium oxide fine particles (average particle size 0.2%, manufactured by Mitsubishi Metals Corporation, W-) whose surface was coated with 1 s wt% c wt%) of stannic oxide (containing 2 wt% antimony oxide) 1) was used as conductive metal oxide particles. This material had a volume resistivity of 10 Ω and was almost white in color.

As a thermoplastic elastomer consisting of a hard segment and a soft segment, hydrogenated 5Is (styrene, isoprene, styrene block copolymer) was used (also referred to as 5EPS; styrene, ethylene, propylene, styrene). block copolymer). This material has a number average molecular weight of about 5oooo, a melting point of 110°C, a styrene content of 39 wt%, rubber elasticity, and a breaking elongation of 5.
It was 80%.

75 wt % of the above conductive white titanium oxide fine particles and 525 wt % of hydrogenated Sl were mixed at a temperature of 210° C. using a gravebender in a shed. In order to uniformly mix the titanium oxide fine particles and lower the viscosity of the mixture, a small amount of titanate-based coupling agent (manufactured by Nippon Qkai Co., Ltd.) is used.
was added during mixing of titanium oxide particles and hydrogenated SIS. The volume resistivity of the thus obtained mixed chip of conductive titanium oxide particles and hydrogenated S↓S is 6 x 103
White conductive composite fibers were created using 6 and 90 conductive chips with an Ω saw.

This conductive chip (B) and a regular polyethylene terephthalate (A) chip (Trrs2 = 256°C, [η) = 0.63 after spinning] were melted in separate extruders, and then they were melted using a composite spinning device. (B) is the core, (3)
A core-sheath composite yarn (composite ratio of (A) and (B) is 80:20 by weight) was spun at 300°C through 4 discharge holes so as to form a sheath part, and at a spinning speed of 4500 m/min. The fiber was divided into two parts and wound up) to obtain a 25 denier/2 filament highly aligned undrawn conductive composite fiber. The obtained fibers are white and 6
The core resistance of the filament was 6×10 8 Ω/3·f.

The obtained fiber is polyethylene terephthalate/cotton = 65
/35 blended yarn, polyethylene terephthalate/cotton =:85/35. 80 warps/1n by inserting 1 in 80 warp threads of cotton count 208/2
A 2/1 twill fabric with 50 pieces/in was used. Next, dyeing and finishing were carried out under normal polyester/cotton mixed fiber conditions. The amount of electrical charge on the fabric is 4.3μ coulombs/d. After being worn as work clothes for one year and washed 100 times during that period, the amount of electrostatic charge was 4.6 μ coulomb/i, making it a woven fabric with excellent static neutralizing performance.

In other words, it has cleared the standard value (hereinafter referred to as the standard value) of 7μ coulombs/rtl in the static electricity safety guidelines issued by the Ministry of Labor's Industrial Safety Research Institute, and has an extremely high durability of K11L. When the conductive fibers were collected from the Maku fabric and the core resistance was measured, it was found to be 1×10Ω/cI11·f, and the rate of decrease in resistance was satisfactory.

Example 2.3 Various conductive mixtures were prepared under the same conditions as in Example 1 by varying the amount of conductive particles mixed. Create a composite fiber using this and evaluate its antistatic performance. The results are shown in Example 2.3 (Table 1.2). In either case, conductive composite 1R fibers with low fiber resistance and good antistatic performance could be obtained. Furthermore, we also evaluated the durability in actual use, and found that it had excellent towing performance in all cases.

Comparative Example 1.2 The mixing ratio of conductive particles was 45 wt% and 9';
A conductive mixture was prepared using wt. The preparation conditions and performance of these products are shown in Comparative Example 1.2 (Table 1.2). When the mixing ratio was 92 wt%, the back life was extremely short and composite fibers could not be spun. When the mixing ratio was 45 wt%, a composite fiber could be easily obtained, but it did not have static elimination performance due to the high resistance value of Rla.

Example 4 Polybutylene terephthalate was used as the sheath component [Product 1 was carried out in the same manner as in Example except -9]. A composite fiber was created. This product has good antistatic performance and excellent durability (Table 1゜2).

Example 5 A conductive composite fiber was prepared in the same manner as in Example 1 except that nylon 6 was used as the sheath component. This product has good anti-static performance and excellent durability.

Example 6 A polyester/polyether type thermoplastic elastomer (Toyobo Belprene P4QH, @-made is shown below. Breaking elongation is 690 inches) was used as a binder. W
-1 should be mixed at 240℃. Other conditions were the same as in Example 1 to produce a conductive composite fiber. This fiber had good antistatic performance and excellent durability (Table 1.2).

Hard Segment FT Segment Example 7 An attempt was made to create a conductive composite fiber using tertiary amine bendane) NB (the structure of which is shown below) and polybutylene ethylene terephthalate as the sheath component. 2,2-dichlorovalaxylene was used as a crosslinking agent for the tertiary amine pendant NBIIIL (1.5 wt% ffl was added to the tertiary amine pendant NB IIIL). Mixing with w-1 was carried out at 210°C. I went there. The resistance value of this composite fiber is 10Ω/
3.f level, and the durability was also excellent (Table 1.2).

Hs Example 8 Conductive particles w-1 and T-1 (manufactured by Mitsubishi Metals, antimony oxide-doped tin oxide, average particle size 0.02 μm)
A conductive conjugate fiber was produced in the same manner as in Example 1 except that a mixture of (W-1:T-1=40:35) was used. This product had good antistatic performance and excellent durability (Table 1.2).

Comparative Example 3.4 A conductive composite fiber was produced in the same manner as in Example 1, except that nylon 6 (crystallinity: 45 degrees) was used as the binder. The mixing ratio of W-1 was 65 or 70 wt, and the mixing temperature was 240°C. Although the antistatic performance of this composite fiber was excellent immediately after its creation, the antistatic performance disappeared after one year of actual use (Tables 1 and 2). If the mixing ratio of W-1 is set to 70W, filter clogging will occur and the pack life will be significantly shortened.

Comparative Example 5 A conductive composite fabric m was prepared by using high-density polyethylene (crystallinity 70%), which is a crystalline thermoplastic resin, as a binder and setting the mixing ratio of conductive particles to 65 wt. The antistatic performance of this fiber was good immediately after it was made, but the antistatic performance disappeared after one year of actual use9.
)X bottom margin 4,

[Brief explanation of the drawing]

Figures 1 to 5 are applicable to the present invention. Composite fiber This is an example of a cross section. In the figure, the shaded area is the conductive layer component. Figure 1 2nd prisoner (B) shows.

Claims (5)

[Claims] (1) White or colorless, consisting of a non-conductive layer component (A) consisting of a fiber-forming thermoplastic polymer and a conductive layer component (B) consisting of a mixture of conductive metal oxide particles and a thermoplastic polymer. A white or colorless conductive composite fiber characterized in that the thermoplastic polymer constituting the conductive layer component is a thermoplastic elastomer. (2) The white or colorless conductive composite fiber according to claim 1, wherein the thermoplastic elastomer is composed of a hard segment and a soft segment. (3) The white or colorless conductive material according to claim 1 or 2, wherein the amount of the conductive metal oxide particles mixed in the conductive layer component is in the range of 50% to 90% by weight. Composite fiber. (4) Claim 1, characterized in that the conductive metal oxide particles are titanium oxide particles whose surfaces are covered with a conductive film containing zinc oxide or tin oxide as a main component.
White or colorless conductive composite fiber according to item 2 or 3. (5) The non-conductive layer component (A) made of a fiber-forming thermoplastic polymer is used as a sheath component, and the conductive layer component (B) made of a mixture of conductive metal oxide particles and a thermoplastic elastomer is used as a core component. The white or colorless conductive conjugate fiber according to claim 1, 2, 3 or 4, characterized by: