JPS58149329A - Production of electroconductive conjugated fiber - Google Patents

Abstract

PURPOSE:After drawn, a specific electroconductive conjugated fiber is heat treated under specific conditions to produce the titled conjugated fiber with good whiteness and suficient tenacity, showing scarce reduction in electroconductivity, when it is processed or used. CONSTITUTION:The objective electroconductive conjugated fiber consists of (A) a fiber-forming thermoplastic polymer and (B) a mixture of cuprous iodide and another thermoplastic polymer with a melting point more than 40 deg.C lower than that of polymer A. After drawn, the resultant fiber is heat treated at a temperature more than 30 deg.C lower than the melting point of polymer A. The share of component B in fiber cross section is 1-50% and the amount of cuprous iodide is preferably 50-80wt% in component B.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing conductive fibers, particularly a novel conductive composite fiber containing fine iodized steel powder as a conductive substance.

Synthetic fibers, such as polyester fibers and polyamide fibers, have low conductivity, so they easily generate static electricity due to friction.
A high potential charge of up to V is observed, and various problems occur due to dust adhesion and discharge.

To solve this problem, it is known that conductive fibers are mixed into textile products, and conductive fibers include metal fibers and metal-plated fibers.

Fibers coated with polymer dope containing conductive substances,
Fibers containing carbon black have been proposed.

However, all of these conventional conductive fibers had serious drawbacks and were not satisfactory. For example, metal fibers do not have bending recovery properties, so their conductive performance decreases when bent during use or processing, mixing with other fibers, and cross-knitting.

It has many drawbacks, such as not being easy to mix and match, and furthermore, having a color tone unique to metal. Metal-plated fibers require a uniform and continuous plating layer to be formed on the fiber surface, so the fiber surface must be smooth.
The types of fibers that can be applied are greatly limited, the plating process must be performed precisely and the manufacturing cost is extremely high, the plating layer easily peels off during use or processing, and the durability is low. It has many drawbacks, such as exhibiting a color tone unique to metals. A bound fiber coated with a polymer dope containing a conductive substance also has the same drawbacks as the above-mentioned metal-plated fiber in terms of manufacturing cost and peeling.

Furthermore, carbon black-containing fibers are colored the black color of carpon plask, and when mixed with synthetic fibers, the appearance is significantly impaired, which has the fatal disadvantage of limiting the field of use.

The inventor of the present invention, as a result of intensive studies aimed at providing a conductive fiber free from the above-mentioned drawbacks, focused on using cuprous iodide as a conductive substance, and developed a fiber-forming thermoplastic resin [(A).
When we attempted to manufacture a composite fiber using component] and a thermoplastic resin containing cuprous iodide [component (B)], we found that
Undrawn yarn exhibits sufficient conductivity, but when stretched to increase yarn strength, the conductive performance i decreases, and as the stretching ratio increases, the decrease in conductive performance becomes more significant. For this reason, it was not possible to draw the fiber at a sufficient magnification, and it was not possible to obtain a conductive composite fiber with excellent yarn strength and conductivity. Therefore, as a result of repeated studies on the thermoplastic polymer in which cuprous iodide in component (B) is blended, we found that a thermoplastic polymer having a melting point 40°C or more lower than the melting point of component (A) was selected as the polymer. It has been found that the electrical conductivity which was significantly reduced during stretching can be recovered by heat treatment at a temperature higher than the melting point of the electrolyte in component (B), preferably at least 10°C higher than the melting point after stretching, and the present invention completed.

That is, the present invention consists of a fiber-forming thermoplastic polymer (A
) and a mixture of cuprous iodide and a thermoplastic polymer having a melting point 40° C. or more lower than the melting point of component (A) after stretching a conductive composite fiber formed from component (B). (B) above the melting point of the thermoplastic polymer in component and (
A) This relates to a method for producing a conductive composite fiber characterized by heat treatment at a temperature 30'O or more lower than the melting point of the component.

The polymer serving as component (A) constituting a part of the conductive fiber of the present invention may be any fiber-forming polymer that can be melt-spun. Specific examples of such polymers include polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6 and nylon 66,
Examples include polyolefins such as polyethylene and polypropylene, and copolymers or mixed polymers containing these as main components. In addition, the polymer constituting component (A) may contain optional additives, such as a matting agent and a coloring agent, if necessary.

Oxidation stabilizers, dyeing improvers, etc. may also be included.

Further, the component (B) constituting the conductive part of the conductive fiber of the present invention consists of fine cuprous iodide powder and a thermoplastic polymer.

The polymer constituting component (B) has a melting point lower than the melting point of the polymer of component (A) by at least 40°C, preferably by at least 50°C, and has thermal stability that does not cause decomposition at the spinning temperature. It may or may not have fiber-forming ability as long as it can be melt-extruded. If the melting point difference of the polymers in component (B) is less than 40'OK*, a decrease in fiber strength or fusion between fibers will occur during the heat treatment after stretching, which will be described later. Specific examples of the polymer in component (B) include polyester, polyamide, polyether, polyolefin, etc., and polymers containing these as main components.

Any method can be used to mix the polymer in component (B) and cuprous iodide as long as it can be dispersed well.

The amount of cuprous iodide mixed varies depending on the required conductive performance, but since conductive fibers for antistatic purposes are required to have an electrical resistance of 1012 Ω/α or less with respect to a DC voltage of I KV, ( Since the volume resistivity of component B) needs to be 11103 Ω·α or less, it is necessary to make it 50% by weight or more. On the other hand, if the amount of cuprous iodide mixed is too large, it will be difficult to adjust the component (B) and spin, so it is appropriate to keep it at 80% by weight or less. Further, optional additives such as a matting agent 2, a coloring agent, an oxidation stabilizer, etc. can be included in the component (B) as required.

The shape of the composite fiber constituted by the above-mentioned (A) component and (B) component may be any shape as long as the (B) component is continuous along the fiber axis direction. However, the core-sheath type in which component (B) is completely surrounded by component (A) is (
8) The antistatic performance is slightly inferior to that in which some of the components are exposed on the fiber surface, so this is not a problem for carpet applications, but for clothing applications that require more severe performance, at least one of component (B) is required. A shape in which a portion is exposed on the fiber surface is preferable. In addition, the combination of polymers used for component (A) and component (B) may be arbitrary in the case of a complete core-sheath type, but
In the case of a partially surface-exposed type, it is preferable to use a polymer of the same type to prevent peeling.

Furthermore, the ratio of component (A) and component (B) in the fiber cross section can be set within a very wide range, but if the ratio of component (B) becomes too large, the strength of the resulting conductive fiber will decrease. Therefore, the area occupied by component (B) in the fiber cross section is preferably 50% or less. Also, this (
The lower limit of component (B) is not particularly necessary as long as component (B) is continuous along the fiber axis direction, but it usually has an area of 1 tlI or more in the cross section of the fiber, especially 3 or more tlI. It is preferable to do so.

A special method for producing such composite fibers.

It is not necessary to adopt these conditions, and the melt spinning method and conditions for producing a two-component composite fiber can be arbitrarily applied to component (A).

In the present invention, the fibers obtained by spinning are stretched to obtain sufficient strength. Any method and conditions for this stretching may be used as appropriate.

As mentioned before, the conductive composite fiber of the present invention does not have sufficient conductive performance when normally spun and drawn, but it does not have sufficient conductive performance when it is normally spun and drawn. By heat-treating at a temperature higher than 10°C, it will have the necessary electrical conductivity. However, heat treatment near the melting point of the polymer of component (A), which is the main component of composite fibers, causes a decrease in fiber strength and fusion between fibers, so the heat treatment temperature is set at the melting point of the polymer of component (A). It is necessary to lower the temperature by 30°C or more. Any means may be employed for such heat treatment after stretching. In addition, at least 10 minutes of processing time is required to fully recover the conductive performance that has decreased due to stretching, but the effect will be saturated even if it continues for more than 60 minutes, so it is appropriate to use up to about 60 minutes. .

The conductive fiber of the present invention uses cuprous iodide powder with high white discoloration as a conductive substance, and forms a common synthetic fiber (
A) Because it contains the component parts, it has extremely good white discoloration and sufficient strength, and can be dyed into any color by conventional methods, and its conductive performance does not deteriorate during processing or use. This method can overcome all the drawbacks of conventional conductive fibers, such as the lack of electrical conductivity, and can be applied to any field where conductive performance is required.

The present invention will be explained in further detail by giving examples below.

The conditions for measuring the volume resistivity of the conductive compositions and conductive fibers used in Examples were 20° C. and ao% aH.

IKV DC voltage. The conditions for measuring the volume resistivity of the conductive fine powder were 20°C, 230°C RH, 3V DC voltage, and 40°C.
It is under 0 mf/- pressure. The melting point of the polymer was measured using a DuPont 900 differential thermal analyzer.

Example 1 100 parts by weight of polyethylene (J 3519.111 point 110°0 manufactured by Ube Industries KK) and 250 parts by weight of cuprous iodide fine powder (volume resistivity 5 x 100・α) were heated for 250 parts by weight under a nitrogen stream at normal pressure. What is the volume resistance value of melted gold at ℃ for 30 minutes? , 2X1
A conductive composition with a resistance of 0''Ω was obtained.

The above conductive composition is used as component (B), polypropylene (
S-115M manufactured by Ube Industries KK, melting point 175℃) (A)
As a component, side pie side type spinning hole (0.3m$
) using a spinneret with 12 holes, and the spinning temperature was 280°C.
At a spinning speed of 400 m/min, an undrawn composite fiber of 450 denier was obtained, with an area ratio of component (A) and component (B) in the fiber cross section of 5:1, and approximately 20 inches of the surface being component (B). . The electrical resistance value of this undrawn composite fiber is 9.2 x 10
It was 'vx. Then, it was stretched 4.0 times at a stretching temperature of 120°C. The electrical resistance value of the obtained drawn fiber was 10Lt.
When it was Ω/1 or more, its conductive performance was significantly reduced. When this fiber was heat treated at 140°C for 30 minutes, the strength was 2409. Elongation 33%, electrical resistance value 3. I x 10'
A conductive fiber of Ω/min was obtained.

Comparative Example 1 A 4-fold drawn composite fiber was produced in exactly the same manner as in Example 1,
This fiber was heat treated at 100°C for 30 minutes. The electrical resistance value of the obtained fiber was 1.3 x 1611Ω/1,
It was rejected as a conductive fiber.

Example 2 Polypropylene (Ube Industries KKIIS-115M.

100 parts by weight (melting point: 175°C) and 22 parts by weight of cuprous iodide (volume resistivity: 5 x 10 Ω/cs+) were melted at 250'O under normal pressure nitrogen flow for 30 minutes to give a volume resistivity of 7.4.
A conductive composition of X 10''Ω·1 was obtained.

The above conductive composition is the component (B), and the intrinsic viscosity is 0.65.
dt/y polyethylene terephthalate (melting point 265
°C) as component (A), concentric core-sheath spinning hole (o, 3m
Component (B) was applied to the core and component (A) was applied to the sheath using a spinneret with 12 holes of φ), and the spinning temperature was 280°C.
At a spinning speed of 400 m/min, an undrawn conjugate fiber of 450 denier and an area ratio of component (A) and component (B) in the fiber cross section of 5:1 was obtained. The electrical resistance of this undrawn composite fiber was 8.3×1 G'Ω. The film was then stretched 4.0 times at a stretching temperature of 120°C. The electrical resistance value of the obtained drawn fiber was 10 LtΩ/c- or more. When this fiber was heat-treated at 180°C for 30 minutes, the strength was 277%.
A conductive fiber with an elongation of 31 inches and an electrical resistance value of 2.5 x 10'Ω/flaw was obtained.

Comparative Example 2 A 4-fold drawn composite fiber was produced in exactly the same manner as in Example 2,
This fiber was heat-treated at 140°C for 30 minutes, and the electrical resistance value of the obtained fiber was 10Ω or more.

Claims (4)

[Claims] (1) Component (A) consisting of a fiber-forming thermoplastic polymer and a mixture of cuprous iodide and a thermoplastic polymer having a melting point 40° or more lower than the melting point of component (A).
B) Stretching the conductive composite fiber formed from component 1.
and (B) above the melting point of the thermoplastic polymer in component (B).
A) A method for producing conductive composite fibers, characterized by heat treatment at a temperature 30° C. or more lower than the melting point of the components. (2) The method for producing conductive composite fibers according to claim 1, wherein the heat treatment time is at least 10 minutes. (3) The method for producing a conductive conjugate fiber according to claim 1 or 2, wherein the area ratio occupied by component (B) in the cross section of the conductive conjugate fiber is 1 to 50%. (4) Claims 1 to 3 in which the amount of ice cream in component (B) is 50 to 80% by weight.
The method for producing a conductive composite fiber according to any one of Item 3.