JPH04153317A - Ultrafine white-colored electrically conductive conjugate fiber - Google Patents

Abstract

PURPOSE:To provide the subject conjugate fiber finer than a specific denier, consisting of a layer composed of a thermoplastic polymer and an electrically conductive layer composed of a mixture of electrically conductive metal oxide particles and a thermoplastic elastomer, having excellent destaticizing effect and durability and useful for clothes, etc. CONSTITUTION:The objective electrically conductive conjugate fiber has a fineness of <=5de (preferably <=4de) and consisting of (A) a non-conductive layer composed of a fiber-forming thermoplastic polymer such as polyethylene terephthalate and (B) an electrically conductive layer composed of a mixture of particles of an electrically conductive metal oxide such as tin oxide (the particle diameter is preferably <=0.05mum) and a thermoplastic elastomer such as polystyrene-polybutadiene-polystyrene block copolymer (the mixing ratio of the metal oxide particle is preferably 60-85wt.%).

Description

[Detailed description of the invention] (Technical field) The present invention provides a conductive composite fiber with excellent static elimination performance.

In particular, it has excellent fiber properties and durability when worn. This relates to a white or colorless (all together referred to as white type in the present invention) ultra-fine conductive composite material that has static elimination performance.〇 (Prior art) Conductive fibers that have conventionally been used as fibers with excellent static elimination performance. Various proposals have been made regarding this. For example, the surface of non-conductive fibers is plated with gold maple to give conductivity,
There is a method in which a conductive coating layer is formed by dispersing conductive carbon black in a resin and then coating the resin surface with the dispersion. However, these can be obtained through complicated manufacturing processes and technically difficult methods, or are difficult to obtain through chemical treatment or actual processing in the preparatory stages before putting conductive fibers into practical use, such as in the scouring process for weaving and knitting. There is a problem in that the conductivity easily decreases due to external effects such as wear during use and repeated washing. As other conductive fibers, metal fibers such as Stiru Sensai are known to have excellent static neutralizing properties, but metal fibers are not compatible with general organic materials, resulting in poor spinnability and problems during the weaving and dyeing processes. or cause trouble.

When worn, wires can easily break or fall off when washed, and furthermore, problems such as electric shocks, sparks, or melting of the fabric can occur due to conductivity.

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 problem, conductive composite fibers using white casings or colorless conductive metal oxide particles have recently been proposed1.

(Problems to be solved) For example, as described in Japanese Patent Publication No. 58-39175.

Antistatic synthetic compositions have been proposed in which 3 to 20 wt% of titanium oxide particles having a stannic oxide film are dispersed in a synthetic polymer. However, in this case, it is difficult to obtain a conductive composite fiber having the desired static elimination performance due to the following two points.

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

b It is difficult to obtain the desired conductive composite fiber at the low particle mixing ratio described in the above publication.

Due to the above two problems, it is impossible to obtain a practically useful conductive composite fiber in this invention. According to the study results of the inventors, the amount of conductive metal oxide mixed must be at least 55 wt%, preferably 5 Q wt% or more.
It is t% or more.

Japanese Patent Publication No. 57-6762, Japanese Patent Publication No. 62-29526
In the publication, when producing a conductive composite fiber of a mixture (conductive layer) of a conductive metal oxide and a thermoplastic resin and a fiber-forming thermoplastic polymer, a composite yarn is produced and seven drawings are performed. A method has been proposed in which the conductive layer broken during stretching is repaired by heat-treating the fiber after stretching. 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 is lost r)tl
Therefore, it cannot play a role as an antistatic fiber. Such heat treatment is necessary when a thermoplastic resin, particularly a highly crystalline thermoplastic resin, is used as the conductive metal oxide binder.

The crystallinity of the thermoplastic resin used in this case is preferably 40% or more, and specifically haoriethylene, polyethylene oxide, and nylon 6 are used. One way to obtain conductive composite fibers is to use a highly crystalline thermoplastic resin as a binder for conductive metal oxides and subject the composite fibers to heat treatment after drawing. The major problem with this conductive composite fiber is that it lacks durability in actual use.

What is the durability of antistatic fibers? For example, when antistatic fibers are woven into antistatic clothing (Q, 1 wt% ~ l Q wt
%) The fabric is actually worn for about one year, and then it is determined whether the fabric has antistatic performance.〇The standard value for the amount of electrostatic charge in the static electricity safety guidelines issued by the Occupational Safety Research Institute of the Ministry of Labor is 7μ coulomb/ rIi'', and it is necessary to be below this value. Conventional white or colorless conductive composite fibers could not satisfy the above durability 'f. For example, if the thermoplastic polymer is The inventors have found that the durability for actual use is insufficient when using a crystalline thermoplastic resin as the thermoplastic polymer. The resistance of the filament is Q x t o 10Ω
/, -f or less, and the antistatic performance of the fabric can also satisfy the charging standard value, but due to poor durability, the antistatic performance of the fabric deteriorates as it is actually worn.

As is well known, anti-static performance refers to the ability to remove charges from a charged object without contact.The inventors of the present invention have conducted extensive studies and found that conventional conductive composite fibers of metal oxide particles) (when a crystalline thermoplastic resin is used as the inder).

The resistance of the filament (hereinafter also referred to as core resistance) is 1×10
When the core resistance is 11Ω/6n-f or less, static electricity is removed by corona discharge, but when the core resistance is 1X10''Ω/crn-f or more, static electricity removal by corona discharge does not occur and no effective antistatic property is shown. For these reasons, anti-static fibers (R-fibers with anti-static properties) must have a filament resistance that does not depend on the conditions under which the fiber is used, and must always be less than 9×1010 Ω/crn-f.

One of the problems with white or colorless conductive composite fibers is that the fibers are thick. Fibers used for clothing generally have a thickness of about 1 to 3 denier, but white conductive composite fibers have a thickness of 10 denier or more. Composite fibers have a problem in that their presence can be visually confirmed in the fibers of clothing. Furthermore, due to the thick conductive fibers, when it is made into a fabric, it has a hard texture. Furthermore, when conductive fibers are used as short fibers, there is a problem that if the single fiber denier is too thick, the carding processability becomes extremely poor when mixed with other [M]. Therefore, it is preferable that the white conductive composite fiber be as thin as possible without losing its static eliminating performance. Preferably 5 denier or less,
More preferably, it is 4 deniers or less.

Conductive composite fibers are based on the fact that the fibers have high conductivity in order to provide antistatic performance. In order to produce thin conductive conjugate fibers, so-called high-speed spinning with a spinning speed of 4000 m/min or higher or 1000 m/min or higher is performed.
A method is used in which a raw yarn spun at a spinning speed of about /min is hot-stretched to about 3 to 4 times the original yarn. In this case, the problem is breakage of the conductive layer. Since the conductive layer has a mixed amount of conductive metal oxide of 50 to 80 wt% (50 to 20 wt% of the polymer material as a binder), the melt viscosity is significantly higher than that of the polymer material forming the fiber sheath component. high,
Furthermore, the strength and elongation in the solidified state are significantly low. For this reason, when attempting to make the conductive composite fiber thinner, the conductive layer is easily broken and the conductivity is lost. A broken conductive layer can be repaired by heat-treating the conductive composite fiber, but if the conductive composite fiber is thin, it is difficult to increase the conductivity of the conductive composite fiber even by this heat treatment.

For this reason, it has been difficult to produce thin conductive conjugate fibers that have static elimination performance.

The biggest problem with conventional white antistatic fibers is that they have poor durability when worn, but thin conductive composite fibers also have performance problems in this regard.

(Means for Solving the Problems) The present inventors have conducted detailed studies on ultrafine conductive composite fibers that have static elimination performance and durability for practical use. In particular, as a result of intensive studies on the conductive structure, fiber structure, static elimination performance, and durability for actual use, we have developed an ultra-fine white conductive composite #! with excellent static elimination performance! The present invention was achieved by discovering the fibers.

The present invention uses a fiber-forming thermoplastic polymer as a non-conductive layer component (
A), a conductive composite fiber in which the conductive layer component CB) is a mixture of conductive metal oxide particles and a thermoplastic resin, in which the thermoplastic resin used for the conductive component is a thermoplastic elastomer; Il! It is an ultrafine white conductive composite fiber characterized by having fibers of 5 denier or less, particularly 4 denier or less.

The most important issue when producing white or colorless ultrafine conductive conjugate fibers is how to avoid the problem of cutting the conductive layer, which is incidental to thinning the conjugate fibers. It is. Furthermore, after obtaining the ultrafine white conductive conjugate fiber, there is a similar problem of how to impart durability to actual use.

The ultrafine white conductive composite fiber is produced by drawing or high-speed spinning. Cutting of the conductive layer often occurs during this step. The method of using a crystalline thermoplastic resin as a binder and applying heat treatment after stretching *m is a useful method for re-adhering the conductive layer cut by the stretching process. The conductive composite fibers lacked durability in actual use. The reason for the lack of durability is that when a thermoplastic resin, especially a crystalline thermoplastic resin, is used as a binder, the broken conductive layer is repaired by heat treatment, and durability is achieved because the conductive layer does not break again. This is because it is not possible.

As a result of intensive studies, the present inventors have found that a conductive composite fiber having a conductive layer made of a mixture of conductive metal oxide particles and a thermoplastic nidistomer has high static elimination performance and high durability in practical use. Furthermore, white conductive composite fibers using a mixture of conductive metal oxide particles and thermoplastic elastomer can be drawn or spun at high speed to easily produce conductive composite fibers with a thickness of 5 deniers or less, especially 4 deniers or less. I found out what I can get. Furthermore, the conductive conjugate fiber obtained in the present invention does not require a step of heat treatment after drawing the fiber, and is useful from the viewpoint of simplifying the process.

The thermoplastic elastomer used in the present invention is
It is a rubber elastic body at room temperature, but at high temperatures (temperature range above the melting point)
is a plasticized, moldable polymeric material. Generally, thermoplastic nidistomers are classified into the following two types.

1. Consisting of unformed molecular chains with easy molecular rotation (referred to as soft segments) and resin molecular chains with high crystallinity or intermolecular cohesion (referred to as hard segments). The soft segment part is made up of hard segments.

2. The basic skeleton is constrained by soft segments, but it is also constrained by ionic crosslinks (dissociated by heat but recombined at low temperatures). As a thermoplastic nidistomer with such a structure, carboxylate polymer, tertiary
Examples include amine pendant NBR.

As the thermoplastic elastomer used in the present invention, any of the above thermoplastic elastomers can be used. The thermoplastic elastomer used in the present invention has rubber elasticity and has a tensile elongation at break (JIs K-6301) of 100%.
As mentioned above, it is better to use a material with a ratio of 200% or more.

Thermoplastic elastomers used in the present invention include 5BS (polystyrene-polybutadiene-polystyrene block copolymer) and its hydrogenated product, 5IS
(polystyrene-polyisoprene-polystyrene block copolymer) and its hydrogenated product, 81 (polystyrene-polyisoprene block copolymer) and its hydrogenated product, etc. from styrenic polymers and conjugated diene polymers. Suitable elastomers include a block copolymer made of a hydrogenated product of a styrene polymer and a conjugated diene polymer, and a block copolymer made of a hydrogenated product of a styrene polymer and a conjugated diene polymer. This block copolymer is particularly excellent in terms of static elimination performance and durability. In these block copolymers, it is particularly preferable that the proportion of styrene polymer is 10 to 50% by weight.If it is less than 10% by weight, spinnability and heat resistance will be poor, and if it is more than 50% by weight, it will stretch and shrink. The conductivity and durability decrease. Note that hydrogenation does not require that all of the double bonds in the conjugated diene polymer be hydrogenated, and it is sufficient that the majority of the double bonds in the conjugated diene polymer are hydrogenated. Examples of the thermoplastic elastomer that can be used in the present invention include polyurethane thermoplastic elastomer, polyester thermoplastic elastomer = 13- polyamide thermoplastic elastomer, sulfonated ethylene propylene rubber, EPDM, tertiary amine pendant NBR, and the like.

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

Examples include oxidized steel, 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 (
Examples of doping agents (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. Adding copper to oxidized steel. Aluminum oxide is added to zinc oxide. The amount of the C doping agent that adds tin or antimony to tin oxide and antimony oxide is determined by the electrical conductivity of the conductive metal oxide particles and the degree of coloration 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 metal oxide particles is 1. Q becomes larger.

To solve this problem, a method was devised to increase the electrical conductivity while maintaining the white state of the conductive metal oxide particles, and one of the methods was to oxidize the surface of the white metal oxide particles. Loosening of conductive coatings on objects is being done. That is, titanium oxide particles whose surfaces are mainly composed of zinc oxide or tin oxide and which use antimony oxide as a doping agent are commercially available from various companies (for example, Mitsubishi Metals W-1, Titanium Industries ECT-52, etc.). These may be used in the present invention.

In order to prevent the particles from being colored, it is also useful to make the particle size of the metal oxide particles smaller than the wavelength of light. Specifically, transparency can be imparted to the particles by adjusting the particle size to 0.01 μm or less, or 0.05 μm or less. In the present invention, even if such transparent conductive metal oxide particles are used, the mixing ratio of the conductive metal oxide particles and the thermoplastic elastomer is determined according to the conductive metal oxide particles. The proportion of conductive metal oxide particles divided into the mixture is 50W℃%~9Q wt
It is better to use %. More preferably 6Qwt% to 85w
It is better to set it as t%, especially the preferred one is 7Qwt%~8Q
It is preferable to set it as wt%.

Conventionally, in the case of crystalline thermoplastic resins that have been proposed as binders for conductive metal oxide particles, when the amount of conductive metal oxide particles mixed exceeds 7Qwt%, the conductivity is further improved. is not observed, and the fluidity of the conductive layer components of the conductive metal oxide particles is significantly reduced, resulting in extremely poor spinnability, and in particular, the life of the bag is significantly shortened due to filter clogging, etc., and process stability is lost. However, when a thermoplastic elastomer was used as the binder, these drawbacks could be overcome.

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

Furthermore, a fluidity improver 1 dispersant may be mixed.

As the fiber-forming polymer forming the non-conductive im(A) of the inventive ultrafine conductive conjugate fiber, any melt-spun polymeric material can be used. For example, various materials such as polyesters such as polyethylene terephthalate +- and polybutylene terephthalate, polyamide 1 polyethylene such as nylon 6, nylon 66, and nylon 12, and polyolefins such as polypropylene are used. Examples of thermoplastic polymers forming the non-conductive layer preferably used in the present invention include polyester polymers containing polyethylene terephthalate and polybutylene terephthalate as a main component. When this polymer is used, processing durability and actual wear durability are significantly improved.

When using polyethylene terephthalate,
The heat resistance (heat decomposition resistance) required for thermoplastic elastomers is 300°C or higher. Thermoplastic nidistomers suitably used under such conditions include hydrogenated products of 818, hydrogenated products of SI, hydrogenated products of SBS,
Polyester-based thermoplastic elastomer Examples include polyester-based thermoplastic elastomer.

The method for spinning the ultrafine white conductive conjugate fiber of the present invention can be applied to any conventional method.

That is, a method using so-called high-speed spinning with a spinning speed of 4000 m/rrun or more, l Q OQm/m
A method may be used in which composite fibers are spun at a speed of in to 3000171 mm/min and stretched 3 to 5 times.

The ultrafine white conductive conjugate fiber of the invention can be made with a single-core or multi-core structure, but it is preferable to have a multi-core structure in order to improve static elimination performance.

In the case of ultra-fine white conductive conjugate fibers, those with a multi-core structure had significantly better static elimination performance than those with a single-core structure.

4- The ultra-fine white conductive composite fiber of the invention has a thickness of 5 deni or more, but it is preferable (7 or 4 deni or more). The fiber is thin
By making the wire thinner, the static elimination performance does not deteriorate significantly, and even when the wire is made extremely thin, such as 4 tenier or less, it has excellent static elimination performance. By setting the thickness to 5 tenier, the presence of conductive fibers in clothing can be made less noticeable, the texture will not be hard, and the cotton blending process will not be impaired.

The composite form of the ultrafine white conductive conjugate fiber according to the second aspect of the present invention may be of any type. Its typical cross-sectional form is shown in FIGS. 1-5. Figure 1 shows an ultra-fine white conductive conjugate fiber with a single core structure. Figure 2 shows an ultra-fine white conductive conjugate fiber with a multi-core structure. FIG. 3 shows a side-by-side type, and FIG. 5 shows a three-layer type.

A preferable structure of the ultrafine white conductive conjugate fiber of the present invention is a core-sheath structure, and a particularly preferable one is a multifilament structure as described above. When used in anti-static cloth 1 It is usually used by mixing 0.1 wt% to 10 wt% into the cloth, as in the case of ordinary conductive fibers. Naturally, these fabrics are completed through a dyeing and finishing process. The conductive layer component contains a large amount of conductive metal oxide particles and is therefore brittle and susceptible to damage by heat, debris, etc. during processing. In particular, for fabrics mainly composed 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. In order to avoid the effects of high-temperature dyeing and high-temperature setting, it was found that conductive composite fibers with a core-sheath structure were the least affected by the process.

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

Examples 1 to 7 Titanium oxide fine particles whose surfaces were coated with tin oxide doped with antimony oxide (average particle size 0.2 μm, Mitsubishi Metals Corporation W-1) were used as conductive metal oxide particles. The volume resistivity of this material was 10 Ω, and the material was almost white (0 thermoplastic elastomer).
Hydrogenated 818 was used as the inder). Its number average molecular weight is 50,000. It has a softening point of 110°C, a styrene content of 30 wt%, has rubber elasticity near room temperature, and has an elongation at break of 580%. 81s3 hydrogenated with the above conductive white titanium oxide particles 7Qwt%
Qwt% were mixed using a small Brabender at a temperature of 210°C. Mix titanium oxide fine particles uniformly,
In addition, in order to lower the viscosity of the mixture, a small amount of titanate-based coupling agents (manufactured by Nippon Soda Co., Ltd., 5151 and 5152) were added during mixing of the hydrogenated SIS and titanium oxide particles.

Several conductive compounds were prepared by changing the binder resin and the mixing ratio as shown in Table 1. In Example 6, P-40H was used as an inder.
was used, which is a polyester ether thermoplastic entomer manufactured by Toyobo.

Using a conductive compound consisting of the binder shown in Table 1 and W-1, an ultrafine white conductive composite fiber was produced.

Chips of this conductive compound (B) and chips of ordinary polyethylene terephthalate (A) are melted in separate extruders, and using a composite spinning device, (B) forms a core part and (A) a sheath part. The core-sheath composite yarn is 300%
℃ through 8 discharge holes, and at the spinning speed shown in Table 1.
The yarn was divided and wound to obtain a multifilament yarn consisting of 4 filaments. All of the obtained fibers were white and had resistance values as shown in Table 1.

The obtained conductive fibers were each cut with a polyethylene terephthalate/cotton blend yarn of 65,735.
A fine count of 208/2 warp threads was applied at a ratio of 1 to 80 to create a 2/1 twill fabric with 80 warp threads/in.Next, dyeing and finishing were performed under the conditions of normal polyester cotton mixed fibers. Ta. The amount of charge on the fabric was as shown in Table 1.

Table 1 shows the amount of charge on the belt after it was actually worn as work clothes for one year and washed and changed 100 times during that time. This result shows that the fabric using the conductive fiber of the present invention has excellent static elimination performance. The standard value of the static electricity safety guidelines published by the Industrial Safety Research Institute is 7μ coulombs/
It passed all criteria 1 and 1, and its durability in actual use was also very excellent. The conductive fibers in the chida fabric were not noticeable and did not impair the J)K combination of the fabric. Furthermore, the conductive m fibers were made into short fibers with a length of 51 gourds, and 1.5 denier short polyester fibers were prepared. When we tested the ability of cards to pass through the mixture, there were no problems in either case.

A uniformly mixed sliver was obtained.

Comparative Example 1 A mixture of nylon 6 and W-1 as a conductive compound (mixing ratio of nylon 6 and W-1).

Ultrafine white conductive composite fibers were spun in exactly the same manner as in Example 1, except that 35 wt%: 65 wt%) was used. The performance of the obtained conductive f&fiber is shown in Table 1. The antistatic performance of this fiber immediately after spinning was excellent, but the antistatic performance disappeared after one year of actual use. .

Comparative Example 2 An attempt was made to produce an ultrafine conductive conjugate fiber having a four-core structure in the same manner as in Example 4, except that a mixture of nylon 6 and W-1 was used as the conductive compound.

Although the spinning process was good, the resistance value of the obtained composite fiber was more than I x 1014Ω/crn-f. As shown in Table 1, this fiber had no static eliminating performance at all. When this composite fiber was observed under an optical microscope, an extremely large number of large cracks were observed in the conductive layer. This crack was never repaired by heat treating the fiber.

Comparative Example 3 A mixture of nylon 12 and W-1 as a conductive compound (mixing ratio of nylon 12 and w-1, 3Qwt%)
A conductive composite fiber was produced in the same manner as in Example 1 except that a near Qwt axen was used. As shown in Table 1, the antistatic performance of this fiber was excellent immediately after spinning, but the antistatic performance disappeared after one year of actual use.

Below is kinpaku

[Brief explanation of drawings]

1 to 5 are representative cross-sectional views of the white conductive composite fiber of the present invention. In the figure, the shaded area indicates the conductive layer (B), and the non-shaded area indicates the non-conductive layer (A). Patent applicant RiRa Shi Co., Ltd.

Claims (1)

[Claims] A conductive composite fiber comprising a non-conductive layer (A) made of a fiber-forming thermoplastic polymer and a conductive layer (B) made of a mixture of conductive metal oxide particles and a thermoplastic elastomer,
An ultrafine white conductive composite fiber characterized in that the fiber has a thickness of 5 deniers or less.