JPS61239011A - Conductive synthetic fiber of polyolefin and production thereof - Google Patents

Abstract

PURPOSE:A polyolefin resin containing conductive carbon black is extruded into fibers and the fibers are drawn under specific conditions to give the titled fiber which has such as a concentration gradient of carbon black as increasing from the center toward the outer surface in the cross section and high electric conductivity, abrasion resistance and strength. CONSTITUTION:(A) 100pts.wt. of a polyolefin resin preferably with a flow rate of 0.1-3.0 are mixed with (B) conductive carbon black, preferably in an amount of 10-50pts.wt. are melt-extruded into fibers. Then, the fibers are kept at 30-60 deg.C and drawn in a bath containing a salt such as calcium chloride at 105-120 deg.C at a draw ratio of 6-12 to give the objective fibers in which the concentration of the carbon black increases from the center toward the outer surface in the cross section. The component B is preferably of less 30mum average particle size, more than 90ml/100g DBP adsorption, more than 50% oil absorption, more than 150m<2>/g BET specific surface area and less than 2% volatile content.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing polyolefin-based synthetic a-fibers with excellent electrical conductivity. , relates to a polyolefin synthetic fiber with excellent abrasion resistance and a method for producing the same.

(Prior Art) Polyolefin synthetic fibers are widely used in many industrial fields because of their excellent physical and chemical properties, as well as their low cost. However, polyolefin synthetic fibers are highly insulating, so they easily induce static electricity.
When used in fields such as chemicals, pharmaceuticals, paint, etc., there is a risk of fire due to electrical discharge @C) Risk of fire, etc.
Sei'6! When used in equipment engineering, etc., measurement and communication failures due to electric induction, etc., and products due to electrostatic attraction and repulsion may occur.
deterioration.

Problems such as decreased work efficiency are occurring.

As a method for improving the drawbacks of polyolefin fibers, for example, a method has been proposed in which polyolefin fibers are fully blended with antistatic fibers such as thin metal wires, metal plated fibers, metallized fibers, and carbon composite synthetic fibers. However, since all of these methods require troublesome manufacturing operations and are expensive, there is a need for a better method.

Conventionally, attempts have been made to manufacture polyolefin fibers with electrical conductivity by incorporating powders or fibers such as carbon black, metal, carbon fibers, and metal fibers into such polyolefin resins and spinning them. Powder and textiles
- When mixed with multi-layered mallet fat, processability and fiber strength will be significantly reduced.

At this time, if the spun yarn is subjected to high drawing treatment, the strength will be improved to some extent, but on the other hand, problems such as extremely reduced conductivity will occur, and a satisfactory result has not yet been obtained! stomach.

(Problems to be Solved by the Invention) The present inventors have completed the present invention as a result of intensive research into a method of imparting conductive gold to polyolefin synthetic fibers. where high i
There are rumors that the company will provide polyolefin-based synthetic fibers with high electrical properties, high strength, and excellent abrasion resistance, and a method for producing the same. Other objects and effects include: from the center of the cross section of the fiber towards the outer surface.

Conductive polyolefin-based synthetic fibers are characterized by having conductive carbon and black dispersed therein so as to increase the concentration gradient, and conductive carbon and gold-containing polyolefin-based resins are completely melt-spun to form spun yarns. By passing it through a cooling tank.

Article 4 (2) [After 130°~60°CKmgt, 7'j,
This is achieved by a method for producing conductive polyolefin synthetic fibers, which is characterized by stretching at a draw ratio of 6 to 12 times under high temperature, humidity, and heat at 105° to 120°C, and simultaneously heat-treating.

An important point in the present invention is that the four-electrode carbon black is dispersed and blended in such a manner that the concentration gradient increases from the center to the outer surface of the polyolefin synthetic fiber. .

The polyolefin synthetic fiber according to the present invention exhibits high conductivity due to the conductive carbon black concentrated on the outer surface of the fiber, and has excellent abrasion resistance. Conductive carbon in the center
Since there is almost no black, it is strong enough to withstand practical use.

Examples of the main component resin of the polyolefin synthetic fiber applied to the present invention include thermoplastic resins obtained by singly or copolymerizing monomers having ethylenically unsaturated double bonds such as ethylene, propylene, and imbutylene. There are no particular restrictions on the synthetic resin, but polyethylene and polypropylene are preferably used. The melt flow rate (MFR) of these polyolefin synthetic resins is preferably 0.1 to 3.0, more preferably 0.3 to 1.0. When MFIIL is less than 0.3, extrudability during melt spinning tends to be low, and stretchability in the subsequent stretching step also tends to be low. On the other hand, MFR is 3.
If it is too large, exceeding 0, the strength tends to decrease.

As for carbon black, the average particle size is 30.
mp Below, BE'! ! -Surface 3150 (vf/f)
above, DBP adsorption amount 90 (layer/7100F) or more, oil absorption fi (FP) 50 (IJ or more, volatile content 2e/Q or less C)
) is suitable for use because it provides high conductivity with a low addition t. About 10 to 50 parts by weight of carbon black ha is blended to 10,033 parts of the polyolefin synthetic resin.

If the amount of carbon black is too small, the conductivity will be insufficient, while if it is too large, the strength will decrease and spinning will become difficult. Melt spinning using such raw materials may be carried out using a conventional kneading/melt spinning means such as a mixing roll, a Pasobar mixer, or an extruder.

There are various forms of raw materials that can be supplied to the spinning equipment, including classified and refined carbon black,
Polyolefin synthetic resin pellets are melt-kneaded to form polyolefin synthetic resin pellets containing carbon black, which is advantageous because contamination with foreign matter can be eliminated.

The undrawn yarn spun from a heated melt extrusion device is maintained at a constant humidity and then subjected to a drawing process.The raw materials such as carbon black and polyolefin synthetic resin used in the present invention are melt-spun. When spinning, by adding metal stone #, it is possible to prevent the formation of so-called eye mucus, where carbon black, etc. adhere to the area around the nozzle, which reduces the occurrence of yarn breakage, uneven fineness, etc., and allows continuous spinning for long periods of time. This is possible and advantageous.

Examples of the metal soap include metal salts of fatty acids such as lithium stearate, barium stearate, and calcium stearate, and derivatives thereof, and these may be used in combination.

It is suitable that these metal soaps are usually blended in an amount of 0.3 to 3 parts by weight. If the amount is too small, a sufficient addition effect cannot be obtained, and if it is added too much beyond the 3N amount, hygroscopicity increases and misalignment such as yarn breakage tends to occur during spinning.

(Effect of the invention) The polyolefin synthetic fiber according to the present invention exhibits high conductivity due to the conductive carbon black concentrated on the outer surface of the fiber, and has excellent abrasion resistance as well. On the other hand, there is almost no conductive carbon black in the center of the cross section of the fibers, and the compaction strength is sufficient for practical use.

The present invention will be explained in detail below with reference to Examples. (Example) Average particle diameter 18 (mu), D B P adsorption amount 125
(g//100F), oil absorption 600e/1, BE'r-
Conductive carbon black 30 with a surface area of 260 (m/f) and a volatile content of 2e/Q! 69 parts by weight of high-density polyethylene of M F R0.8, 1 part of lithium stearate
100 parts by weight of the mixture was formed into pellets using a pelletizer equipped with a vented extruder,
This is screwed into a screw with a diameter of 65φ with a die for monofilament having 150 small holes of diameter 1fiφ at the tip.
, extrude the yarn using an extruder with L/D=28,
The extruded yarn is cooled by passing through a cooling tank whose humidity is adjusted to 40"C, and then stretched at a stretching ratio of 4 to 10 times in a calcium chloride salt bath drawing tank whose temperature is adjusted to 115C in the first stage. - Pick up while heat treating.

At this time, the spinning speed was 100 (m/min) and the spinning time was 12 hours, but the operation continued in good condition from start to finish without causing any buildup or yarn breakage around the nozzle outlet. Ta.

The results obtained are shown in Table tm1.

Comparative Example 1 In the example, the addition rate of conductive carbon black was 5
The same procedure was carried out except that the parts by weight and the high-density polyethylene were 94 parts by weight, but a monofilament having good conductivity could not be obtained.

Comparative Example 2 In the example, the addition rate of conductive carbon black was 6
The same procedure was carried out except that 0 parts by weight and 39 parts by weight of high-density polyethylene were used, but the extrudability decreased, thread breakage occurred frequently, and fibers could not be produced.

Comparative Example 3 The same procedure as in Example 5 was repeated except that the stretching humidity was 99° C. and the boiling water bath was used, but good conductivity was not obtained and yarn breakage occurred.

Results of Comparative Examples 1 to 3 Table 1 Results of all Examples

Claims (11)

[Claims] (1) A conductive polyolefin synthetic fiber characterized in that conductive carbon black is dispersed and blended so that the concentration gradient increases from the center of the cross section of the fiber to the outer surface. (2) The conductive polyolefin synthetic fiber according to claim (1), wherein 10 to 50 parts by weight of conductive carbon black is dispersed in 100 parts by weight of the polyolefin resin. (3) The conductive polyolefin synthetic fiber according to claim 1 or 2, wherein the polyolefin resin has a melt flow rate (MFR) of 0.1 to 3.0. . (4) Conductive carbon black has an average particle diameter of 30 mμ
Below, DBP adsorption amount is 90 (ml/100g) or more, oil absorption amount is 500 (%) or more, BET-surface area is 150 (m^2/
The conductive polyolefin synthetic fiber according to any one of claims (1) to (3), which has a volatile content of at least g) and at most 2 (%). (5) Polyolefin resin containing conductive carbon black is melt-spun, and the humidity of the spun yarn is adjusted to 30° to 6°C.
After maintaining at 0℃, 6-1 under heating at 105℃~120℃
A method for producing a conductive polyolefin synthetic fiber, which comprises stretching at a stretching ratio of 2 times. (6) Conductive carbon black has an average particle diameter of 30 mμ
Below, DBP adsorption amount is 90 (ml/100g) or more, oil absorption amount is 500 (%) or more, BET-surface area is 150 (m^2/
g) The method for producing a conductive polyolefin synthetic fiber according to claim (5), which has a volatile content of at least 2 (%). (7) 10 to 50 parts by weight of conductive carbon black is dispersed in 100 parts by weight of the polyolefin resin, according to claim (5) or (6).
A method for producing a conductive polyolefin synthetic fiber as described in 2. (8) The conductive polyolefin according to any one of claims (5) to (7), wherein the polyolefin resin has a melt flow rate (MFR) of 0.1 to 3.0. A method for producing synthetic fibers. (9) The method for producing a conductive polyolefin synthetic fiber according to any one of claims (5) to (8), wherein the stretching is carried out in a salt bath. (10) The salt bath contains calcium chloride (CaCl_2), potassium hydroxide (KOH), potassium carbonate (K_2CO_
3), magnesium chloride (MgCl_2), sodium hydroxide (NaOH), or sodium nitrate (NaNO_
3) The method for producing a conductive polyolefin synthetic fiber according to claim (9). (11) Stretching is ethylene glycol, triethylene
The method for producing a conductive polyolefin synthetic fiber according to any one of claims (5) to (8), which is carried out in glycol or silicone oil.