JPH04153305A - White color-based electroconductive fiber - Google Patents

Abstract

PURPOSE:To obtain the subject white color-based or colorless-based fiber having excellent antistatic properties and practical wearing durability by using a mixture of specific electroconductive metal oxide particles and a thermoplastic elastomer as an electroconductive layer component. CONSTITUTION:The objective fiber is composed of (A) a non-electroconductive component composed of a fiber-forming thermoplastic polymer (preferably polyethylene terephthalate, etc.) and (B) an electroconductive layer component composed of a mixture of electroconductive metal oxide particles comprising electroconductive indium oxide particles having 0.01-2mum average particle size and a thermoplastic polymer comprising a thermoplastic elastomer so as a mixing amount of the metal oxide particles to be 50-90wt.%. Besides, as the thermoplastic elastomer constituting the component B, a block copolymer comprising a styrenic polymer and a hydrogenated conjugate diene-based polymer is preferable from the viewpoint of antistatic properties and durability.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides a conductive composite fiber with excellent static elimination performance, especially fiber physical properties and wearing durability. This paper relates to dielectric composite fibers with improved static elimination performance.

More specifically, the fiber-forming polymer is used as a non-conductive layer component (A
), and the conductive layer component (B) is a thermoplastic polymer containing a conductive metal oxide, and the conductive composite fiber is a white or colorless composite fiber with excellent static elimination performance. Concerning conductive composite fibers that can be obtained by adding 0.01 wt % to 10 wt % (wt %) to the fibers and have excellent static neutralizing performance, and whose static neutralizing performance does not deteriorate much even after one year of actual use. It is.

(Prior art) Various proposals have been made regarding conductive fibers as fibers with excellent static elimination performance.For example, there has been a method of imparting conductivity by plating the surface of non-conductive fibers with metal. There are also methods in which conductive carbon black is dispersed in a resin and then coated on the fiber surface to form a conductive coating layer. However, these can be obtained through complex manufacturing processes and technically difficult methods, or are difficult to obtain through chemical treatment or actual processing in the preparatory stages for putting conductive fibers into practical use, such as in the scouring process for weaving and knitting. During use, there is a problem that the conductivity easily decreases due to abrasion, repetition, loss of focus, and other external effects, making it beyond the scope of practical use. As other conductive fibers, metal fibers such as steel fibers are known to have excellent static neutralizing properties, but metal fibers are not compatible with general organic materials, resulting in poor spinnability and problems in the weaving and dyeing finishing processes. This may cause trouble with the
It is easy to fall off, and furthermore, it causes problems such as electric shock and sparks due to the conductivity, and problems such as melting of the fabric. In order to alleviate 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.

(Problems to be Solved by the Invention) For example, as disclosed in Japanese Patent Publication No. 5G-39175, antistatic synthesis is achieved by dispersing 3 wt% to 20 wt% of titanium oxide particles having a stannic oxide coating in a synthetic polymer. Polymer compositions have been proposed. However, in this case, it is difficult to obtain a conductive composite fiber having the desired static elimination performance for the following two reasons.

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

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

Due to the above two problems, practically useful conductive composite fibers cannot be obtained using the above-mentioned known techniques. According to the study results of the present inventors, the content of the conductive metal oxide needs to be at least 55 wt%, and preferably 60 wt%.
or more is required.

Japanese Patent Publication No. 57-6762, Japanese Patent Publication No. 62-29526
In the publication, when producing a conductive composite fiber of a mixture of a conductive metal oxide and a thermoplastic resin (conductive layer) and a fiber-forming thermoplastic polymer, a composite spun yarn is produced and drawn. A method has been proposed in which the conductive layer is melted and made continuous by further heat-treating the fiber after the conductive layer is repaired. That is, when a thermoplastic resin is used as a binder for a conductive metal oxide, cutting of the conductive layer occurs during the stretching process. In this state, it cannot function as an antistatic fiber because it has lost its conductivity. 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 publication has the disadvantage of poor production efficiency due to the presence of a heat treatment process after drawing.
Moreover, the widely available antistatic fibers still have a major drawback of lacking in durability.

Furthermore, in the technique described in the above-mentioned Japanese Patent Publication No. 62-29526, a thermoplastic resin with a high degree of crystallinity is used as a thermoplastic resin suitable as a binder for conductive metal oxides. Although it is mentioned,
Conductive composite fibers obtained using polymers with a high degree of crystallinity have a problem in that they lack durability when worn.

As is well known, anti-static performance refers to the ability to remove the electric charge from a charged object without 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 the resistance is less than
If it is 10"Ω/cm-f or more, static elimination will not occur by corona discharge, and it will not exhibit effective antistatic properties. For this reason, antistatic fibers (fibers that have static elimination performance) are those whose filament resistance is Regardless of the usage conditions of the fiber, it is always 9
It must be no larger than 10" x 97cm4.

The durability of antistatic fibers refers to the durability of antistatic fibers, for example, in the case of antistatic clothing, which refers to whether or not antistatic performance exists when a fabric woven with 0.1wt% to 10wt% of electrostatic fibers is actually worn for about one year. judge. The basic value of the amount of electrostatic charge in the static electricity safety guidelines published by the Ministry of Labor's Occupational Safety Research Institute is 7 micron/m2, and it is necessary that the value be below this value. Conventional white or colorless conductive composite fibers have not been able to satisfy the above durability. For example, if the thermoplastic polymer is polyethylene, its durability for actual use is insufficient;
As a result of the inventors' studies, it has been found that it is not suitable for use in particularly dangerous work such as wearing 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 9X 1010 Ω/cm4 or less, which satisfies the charging standard value for textiles. However, due to poor durability, the antistatic performance of the fabric deteriorates, making it difficult to use in practice. The reason why the durability is not good when a crystalline thermoplastic resin is used is that the conductive structure of the antistatic edge 9a is easily broken because the crystalline thermoplastic resin is brittle.

(Means for Solving the Problems) The present inventors conducted detailed studies in order to provide a conductive composite fiber free of such drawbacks. In particular, as a result of intensive research into fiber structure, static elimination performance, and durability in actual use, we discovered a white or colorless conductive conjugate fiber that has excellent static elimination performance and durability in actual use, and arrived at the present invention. .

The gist of the present invention is to form a conductive composite comprising a fiber-forming thermoplastic polymer as a non-conductive component (A) and a mixture of conductive metal oxide particles and a thermoplastic resin as a conductive component (B). A fiber, in which the thermoplastic resin used in the conductive component is a thermoplastic elastomer, and the conductive metal oxide particles are conductive indium oxide particles having an average particle size of 0.01 to 206 m, and The conductive composite fiber is characterized in that the amount of the conductive metal oxide particles mixed in the conductive layer component is 50 to 90% by weight. Conductive composite fibers that satisfy these conditions have a filament resistance of 9×
It was 1010 Ω/em-r or less and had excellent durability for actual wear.

The most important issues when obtaining white or colorless antistatic fibers are whether the conductive layer is often cut during the drawing process of composite fibers, and how to solve this problem. There are two points: how to impart durability. The method of using a crystalline thermoplastic resin as a binder and applying heat treatment after stretching the fiber is an effective method for rebonding the conductive layer cut by the stretching process, but the According to the study results of the present inventors, the conductive composite fiber lacks 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, a broken conductive layer can be repaired by heat treatment, but the conductive layer itself is inherently brittle. This is because the conductive layer breaks again during repeated expansion and contraction during actual use, 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 heat treatment step 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). -For boat fishing, thermoplastic elastomers are classified into the following two types.

■Three molecules are composed of amorphous molecular chains that rotate easily (referred to as soft segments) and highly crystalline resin molecular chains (referred to as hard segments). Portions of the soft segment are constrained by portions of the hard segment.

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). Thermoplastic elastomers with this structure include carboxylate polymers,
Examples include tertiary amine bendant NBR.

As the thermoplastic elastomer used in the present invention, any of the above thermoplastic elastomers can be used, but it must have rubber elasticity and have a tensile elongation at break (JISK-6301) of 100% or more. , preferably 200% or more.

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

The thermoplastic elastomer used in the present invention includes SBS (polystyrene-polybutadiene-polystyrene block copolymer) and its hydrogenated product, 5I
Styrenic polymers and conjugated diene polymers represented by S (polystyrene-polyisoprene-polystyrene block copolymer) and its hydrogenated product, SI (polystyrene-polyisoprene block copolymer) and its hydrogenated product, etc. Suitable elastomers include a block copolymer consisting of or a hydrogenated product of a styrene polymer and a conjugated diene polymer,
In particular, a block copolymer made of a hydrogenated product of a styrene polymer and a conjugated diene polymer is particularly excellent in terms of static elimination performance and durability. Among these block copolymers, those in which the proportion of the styrene polymer is 10 to 50% by weight are particularly preferred; if it is less than 10% by weight, the spinnability and heat resistance will be poor, and if it is 50% by weight or more, the elasticity and durability will be poor. Some conductivity decreases. Note that hydrogenation does not require that all of the double bonds in the conjugated diene polymer be hydrogenated, and it is sufficient that only a majority of the double bonds in the conjugated diene polymer are hydrogenated.

Other thermoplastic elastomers that can be used in the present invention include polyurethane thermoplastic elastomers, polyester thermoplastic elastomers, polyamide thermoplastic elastomers, sulfonated ethylene propylene rubber, E
Examples include PDM, tertiary amine pendant NBR, and the like.

As the fiber-forming polymer forming the non-conductive layer (A) of the conductive composite fiber of the present invention, any polymeric material that can be melt-spun may be used. For example, various kinds of polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6 and nine-66, and polyolefins such as polyethylene and polypropylene are used. More preferably used thermoplastic polymers forming the non-conductive layer include polyester polymers containing polyethylene terephthalate and polybutylene terephthalate as main components. 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 elastomers suitably used under such conditions include hydrogenated products of SIS, hydrogenated products of SI, hydrogenated products of SBS,
Examples include polyester thermoplastic elastomers and polyamide thermoplastic elastomers.

The conductive metal oxide particles used in the present invention are conductive indium oxide particles (ITO). 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, tin oxide is added to indium oxide. The amount added is 2 to 25% by weight based on indium 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 in order to improve the electrical conductivity of the particles, although the electrical conductivity increases, the degree of coloring of the conductive particles increases.

Conventionally, as a conductive metal oxide, titanium oxide particles whose surface is mainly composed of zinc oxide or tin oxide and antimony oxide as a doping agent have been widely used. The one with increased doping agent nails is gray and is not suitable for white conductive fibers. In contrast, conductive indium oxide (I To)
The particles are pale yellow in color, even though they are highly conductive, making them highly suitable for the present invention.

In the present invention, the conductive particles have an average particle diameter (median diameter:
In the sedimentation method), those with a diameter of 2 μm to 0.01 μm are preferred because they can increase electrical conductivity and have good spinning process properties.

In order to increase the electrical conductivity of the mixture, the ITO particles must be brought into contact with each other. For this purpose, it is important to increase the concentration of TTO in the mixture and to cause aggregation of TTO particles.

Generally, when a flexible or fluid polymeric material such as a silicone elastomer or a liquid elastomer is used as a binder, the amount of TTO particles mixed can be extremely increased.

According to the study results of the present inventors, when such a polymer material is used, the mixing amount of TTO particles is 80 to 9
It can be increased to about 0 wt%. However, in this case, although it is possible to increase the amount of ITO particles mixed, it is difficult to increase the electrical conductivity of the mixture. For these reasons, it has not been possible to obtain a conductive composite fiber with a low resistance value even if a highly fluid polymeric material is simply used as the binder and the amount of ITo particles mixed is increased. In contrast, when thermoplastic elastomers are used, high mixing ratios and moderate agglomeration occur, making it possible to avoid the above-mentioned drawbacks.

In the present invention, the mixing ratio of the ITO particles and the thermoplastic elastomer is in a range such that the role of the ITO particles in the conductive mixture is 50 to 9 (1 wt%), preferably 60 to 9 (1 wt%).
~85wt%, particularly preferably 70~80wt%
It is. In the case of crystalline thermoplastic resins that have been proposed as binders for IT and 0 particles, no further improvement in conductivity was observed when the amount of TTO particles exceeded 70 W t%. 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, when thermoplastic elastomers were used, these drawbacks could be overcome.

In the present invention, when producing a mixture of thermoplastic elastomer and ITO particles, a surface treatment agent for ITO particles may be added. Furthermore, a fluidity improver, a dispersant, etc. may be mixed.

The conductive conjugate fiber of the present invention can be produced by a conventional method for producing conjugate fibers. That is, it may be used as a drawn yarn obtained by drawing the original yarn of a composite spun fiber, or by performing high-speed spinning, a highly oriented undrawn conductive composite fiber can be directly obtained without 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, Figure 3 shows a side-by-side type, Figure 4 shows a multilayer side-by-side type, and Figure 5 shows a three-layer type. be. 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 in an antistatic cloth, it is usually mixed in the cloth at 0.1 wt% to low wt%, as in the case of ordinary conductive fibers. Naturally, these fabrics are completed through a dyeing and finishing process. In general, conductive layer components contain a large amount of ITO particles and are therefore brittle and susceptible to damage from hot chemicals and the like 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 being affected by high-temperature dyeing and high-temperature setting, composite conductive fibers with a core-sheath structure are most unaffected by the process.

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

[Example 1] 0.5 mol/Q of indium nitrate and tin sulfate at 9°1 (
ITO particles were obtained by spraying the mixed aqueous solution (molar ratio) using a commercially available two-fluid nozzle (Akijet, manufactured by Ikeuchi Co., Ltd.) into a quartz reactor heated to 900° C. in a heating furnace. The obtained ITO particles were pale yellow particles with an average particle size of 0.2 μm and a volume resistivity of 1.0 Ω·cm.

Hydrogenated SIS was used as the thermoplastic elastomer consisting of hard segments and soft segments. This product has a number average molecular weight of 50,000 and a melting point of 110.
℃, the styrene content was 30 wt%, it had rubber elasticity, and the elongation at break was 580%.

The above ITO fine particles 75wt% and hydrogenated Sl 525w
t% were mixed using a small Brabender at a temperature of 210°C. In order to uniformly mix the ITO particles and lower the viscosity of the mixture, a small amount of a titanate-based coupling agent (manufactured by Nippon Soda Co., Ltd.) was added during the mixing of the ITO particles and the hydrogenated SIS. I obtained in this way
The volume resistivity of the mixed chip of TO particles and hydrogenated SIS was 4×10′Ω·cm. A white conductive composite fiber was produced using this conductive chip.

This conductive chip (B) and a normal polyethylene terephthalate (A) chip (Tm2 = 256°C, [η] -0.63 after spinning) were melted in separate extruders, and a composite spinning device was used to melt them. A core-sheath composite yarn (composite ratio of (A) and (B) is 80.20 by weight) was heated at 300°C with 4 holes so that (B) forms the core and (A) forms the sheath. It was spun through a discharge hole, divided into two parts at a spinning speed of 4500 m/min, and wound up to obtain a highly oriented undrawn conductive composite fiber of 25 denier/2 filaments. The obtained fiber was pale yellow, close to white, and the filament core resistance was 6 x 108 Ω/cm-f.
Met.

The obtained fiber is polyethylene terephthalate/cotton-65
Covering with a blended yarn of /35, polyethylene terephthalate/cotton-65/35, cotton count 2os/2 warp yarn at a ratio of 7 to 1 in 80 to create 80 warp yarns/
A 2/l twill fabric with 1n50 pieces/in was used. Next, dyeing and finishing were carried out under the conditions of ordinary polyester/cotton mixed fibers. The conductive threads in the fabric were inconspicuous and of good quality. The amount of electrical charge on the fabric is 3.5 μ coulombs/m t
Met. Worn as work clothes for one year, during which time 100
The amount of charge after repeated washing was 3.5 μcoulombs/m 2 , indicating that the woven fabric had excellent static elimination performance. In other words, the standard value (hereinafter referred to as the standard value) of the static electricity safety guidelines issued by the Industrial Safety Research Institute of the Ministry of Labor) is 7μ clone/
It cleared m2 and had very good durability.

Further, when the conductive fibers were collected from the woven fabric and the core resistance was measured, it was found to be 9×10 8 Ω/cm 4 , and the rate of decrease in resistance was satisfactory.

Example 2.3 Various conductive mixtures were prepared under the same conditions as in Example I by varying the amount of ITO particles mixed. Composite fibers were produced using this, and their antistatic performance was evaluated. The results are shown in Example 2.3 (Table 12). In either case, conductive composite fibers with low fiber resistance and good antistatic performance could be obtained. Moreover, the fabric was also good, with the conductive threads being inconspicuous. Furthermore, durability in actual use was also evaluated, and it was found that it had good performance in all cases.

Comparative Example Ratio 2 A conductive mixture was prepared with a mixing ratio of TTO particles of 45 wt% and 92 wt%. The manufacturing conditions and performance of these products are shown in Comparative Examples 1 and 2 (Tables 1 and 2). When the mixing ratio was 92 wt%, the pack life was extremely short and composite fibers could not be spun.

When the mixing ratio was 45 wt%, composite fibers could be easily obtained, but the fibers had a high resistance value and did not have static elimination performance.

Example 4 A conductive composite fiber was produced in the same manner as in Example 1 except that polybutylene terephthalate was used as the sheath component.

This product had good antistatic performance and excellent durability (Table 12).

Example 5 A conductive composite fiber was produced in the same manner as in Example 1 except that nylon 6 was used as the sheath component. This product had good antistatic performance and excellent durability.

Example 6 A polyester/polyether type thermoplastic elastomer (Toyobo Perprene P 40H, the structure of which is shown below. Breaking elongation is 690%) was used as a binder.

Mixing with ITO was performed at 2408C.

Other conditions were the same as in Example 1 to produce a conductive composite fiber. Although the antistatic performance of this fiber was inferior to that when hydrogenated SIS was used as a binder, it was still good and had excellent durability (Table 1
,2).

Hard Segment Soft Segment Example 7 Using tertiary amine pendant NBR (the structure is shown below) and polybutylene terephthalate as a sheath component, an attempt was made to produce a conductive composite fiber. 2.2'-dichloroparaxylene was used as a crosslinking agent for the tertiary amine pendant NBR (1.5 wt% was added to the tertiary amine pendant NBR).The mixture with ITO was 210'
I went with C. Although the antistatic performance of this composite fiber was inferior to that when hydrogenated SIS was used as the binder, the resistance value was at the level of 109Ω/cm4 and the durability was also excellent (Tables 1 and 2). .

L Comparative Example 3.4 A conductive composite fiber was produced in the same manner as in Example I except that nylon 6 (crystallinity 45%) was used as the binder. The mixing ratio of ITO is 65 or 70 wt%,
The mixing temperature was 240°C. The antistatic performance of this composite fiber was excellent immediately after production, but the antistatic performance had disappeared after one year of actual use (Table 1.2). The mixing ratio of ITO is 7
When it was set to 0 W t%, filter clogging occurred and the pack life became extremely short.

Comparative Example 5 A conductive composite fiber was produced using high-density polyethylene (crystallinity: 70%), which is a crystalline thermoplastic resin, as a binder, and the mixing ratio of conductive particles was 65 wt%. Although the antistatic performance of this fiber was good immediately after production, the electrostatic performance had disappeared after one year of actual use.

Margin below

[Brief explanation of the drawing]

FIGS. 1 to 5 are representative cross-sectional views of composite fibers to which the present invention can be applied. In the figure, the shaded area is the conductive layer component (B)
shows.

Claims (1)

[Claims] (1) Conductive layer 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. In the composite fiber, the thermoplastic polymer constituting the conductive layer component is a thermoplastic elastomer, and the conductive metal oxide particles are conductive indium oxide particles having an average particle size of 0.01 to 2.0 μm. A conductive composite fiber characterized in that the amount of the conductive metal oxide particles mixed in the conductive layer component is in the range of 50% to 90% by weight.