JPH0122367B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to conductive fibers, particularly novel conductive conjugate fibers whose conductive component is a conductive polyester composition containing 4% by weight or less of extracted low molecular weight substances. BACKGROUND ART Polyester fibers, particularly polyethylene terephthalate fibers, have excellent dimensional stability, heat resistance, and chemical resistance, and are therefore widely used as fiber materials for clothing and industrial applications. However, static electricity is generated due to friction, and static electricity problems such as spark discharge and adhesion of dust caused by this are very troublesome. Such electrostatic damage also occurs in textile products such as nylon and wool, and an effective means to solve this problem is to bond a conductive component made of a polymer with conductive carbon black dispersed therein and a protective component made of a fiber-forming polymer. There is a method of mixing a small amount of conductive composite fibers, and it is attracting attention as the most effective method in that it can provide permanent antistatic properties. However, in order to impart antistatic properties, it is necessary to disperse a large amount of conductive carbon black, and in the case of aromatic polyesters such as polyethylene terephthalate, moldability decreases, especially productivity in the stretching process. Decrease becomes a problem. Aromatic polyesters have long been mentioned as matrix polymers for conductive components, but there are few concrete examples, and only a few
No. 45851 discloses a method for preventing clogging by increasing the shear rate of polymer tubes to 0.001 or more, and improving prevention and twistability, and JP-A-56-68110 and JP-A-56-85423.
No. 2, it is proposed to improve the spinning/drawability and conductivity by mixing polyalkylene oxide or the like. As described above, the development of polyester conductive conjugate fibers has lagged behind that of polyamide, and very few have been put into practical use. Against this background, the present inventors conducted research aimed at improving the molding processability of conductive polyester compositions, and found that conductive polyesters containing 3% by weight or less of extracted low-molecular-weight substances solid-phase polymerized had excellent molding processability. (proposed in Japanese Patent Application No. 59-121069 and Japanese Unexamined Patent Publication No. 61-256), and the conductive composite fiber melt-spun using this fiber has excellent spinnability and yarn performance. The present inventors have also found that the present invention can be improved. Problems to be Solved by the Invention It is an object of the invention to provide a conductive composite fiber of polyester having excellent spinning processability and improved yarn performance. The present invention provides a conductive conjugate fiber suitable for use in polyester fiber products that are required to have properties such as strength, heat resistance, and chemical resistance to impart antistatic performance. Means for Solving the Problems That is, the present invention provides a polyester polymer 60 containing ethylene terephthalate as a main repeating unit.
-85% by weight of conductive carbon black and 15-40% by weight of conductive carbon black are dispersed by kneading and then solid phase polymerized to form a conductive component, and a non-conductive component consists of a non-conductive fiber-forming polyester polymer. conductive component, the conductive component contains 4% by weight or less of an extracted low molecular weight substance, and 10 ⁷
It concerns conductive composite fibers with a specific resistance of less than Ω·cm. The polyester polymer as a conductive component used in the present invention is a thermoplastic polyester formed from a dicarboxylic acid component whose main component is terephthalic acid or an ester-forming derivative of terephthalic acid, and a glycol component whose main component is ethylene glycol. It is a polymer whose main repeating unit is ethylene terephthalate. This polyester polymer can be arbitrarily selected as long as it can be solid-phase polymerized, but fiber-forming ones are preferred from the viewpoint of spinnability. Examples of dicarboxylic acid components to be copolymerized include isophthalic acid, 2,6-naphthalene dicarboxylic acid, adipic acid, and sebacic acid, and examples of ester-forming derivatives include lower alkyl esters (such as methyl esters) and diaryl esters of these dicarboxylic acids. (For example, phenyl ester). Glycol components include tetramethylene glycol, cyclohexane 1,4 dimethanol, neopentylene glycol, 2-2-bis(4-hydroxyphenyl)
Examples include propane and polyethylene glycol. Dispersion of conductive carbon black into polyester polymer is carried out by stirring and mixing in a molten state (kneading).
However, it is preferable to make the dispersion as uniform as possible. If necessary, it is also preferred to add a small amount of a fluidity improver (for example, a plasticizer, waxes, low viscosity polymers such as polyalkylene oxide). The mixing ratio of conductive carbon black varies depending on the type, conductivity, chain-forming ability, and properties and crystallinity of the polyester polymer, but it is usually in the range of 15 to 40% by weight, and in most cases 20% by weight.
~35% by weight. The mixture obtained by kneading is brittle and has a drawback of extremely poor melt fluidity. The reason for this is that in order to uniformly disperse a large amount of conductive carbon black, the polyester polymer is pulverized and kneaded for 2 to 30 minutes.
Repeatedly four times, the slight amount of water contained in the ground material of conductive carbon black or polyester polymer is added during kneading (normally, it is difficult to dry the powder sufficiently, and this is rarely done). It is presumed that this is inducing decomposition. actual,
The mixture obtained by kneading contains 4 to 4 extracted low molecular weight substances.
It often contains 10%. The conductive polyester composition used in the present invention can be obtained by solid phase polymerization of the above mixture. To improve molding processability, extract low molecular weight substances
% or less, particularly preferably about 1% or less. Solid phase polymerization is a method in which the polycondensation reaction is advanced by heating pellets of the above mixture at a temperature below the melting point (often 200 to 240°C) under reduced pressure or while aerating inert gas. Ru. The extracted low-molecular substance is a ground sample 1 of a conductive polyester composition.
g and 10 ml of chloroform are sealed in a glass ampoule, heated at 120°C for 2 hours, and after cooling, the low molecular weight substances (mainly those with a molecular weight of several thousand or less) dissolved in the chloroform are determined. Further, the extracted low molecular weight substance of the conductive component in the composite fiber is calculated by regarding the extracted low molecular weight substance of the fiber consisting only of the protective component as that of the protective component in the composite fiber. The polyester polymer constituting the non-conductive protective component of the fiber of the present invention may be any fiber-forming polymer, but polyethylene terephthalate, polybutylene terephthalate, and copolymers or mixtures thereof are preferred. In particular, polyethylene terephthalate is currently commercially produced in the largest quantity and is most suitable as a protective component for conductive composite fibers, which are often used in combination with polyethylene terephthalate. Also,
Their dye receptivity can also be improved by known methods to facilitate blending or interdying with synthetic or natural fibers. Alternatively, matting agents, pigments, coloring agents, stabilizers, antistatic agents, etc. may be added according to the purpose by known methods. The combination of polyester polymers as the conductive component and the protective component is preferably a combination of the same or similar polyesters from the viewpoint of preventing peeling due to stretching or the like. However, if the composite structure is of a core-sheath type, even combinations that involve peeling are unlikely to pose a serious problem. The fiber of the present invention can be produced by a melt composite spinning method, but it is necessary to keep the extracted low molecular weight substance of the conductive component to 4% or less. In such fibers, the conductive polyester composition as the conductive component has a significantly high melt viscosity, and the shear rate is particularly low.
It tends to increase rapidly below about 10 ² sec ^-1 (for example, it is 3 to 300 times that of polyethylene terephthalate for textiles, and even compared to nylon 6 mixed with 30% by weight of conductive carbon black, it is 10
~100 times), and since the amount of extracted low-molecular substances increases by melt spinning (about 2 to 8% in most cases), it can be produced by special measures as described below. That is, (A) melt extrusion at high pressure, (B) make the flow path from melt extrusion to discharge from the nozzle as short as possible and increase the flow rate, (C) at least both components meet at the internal orifice of the nozzle. It is necessary to maintain a stable composite structure by setting the shearing rate immediately before to about 10 ² sec ^-1 or more so that the protective components merge in a state with the same melt fluidity as the protective component. The fibers of the present invention contain 4% or less of extracted low molecular weight substances as conductive components, and have excellent spinning properties and improved yarn performance. In particular, those containing 2% or less of extracted low molecular weight substances have a remarkable improvement effect on spinning properties and yarn performance, and are suitable examples of the present invention. On the other hand, fibers in which a mixture before solid phase polymerization is used as a conductive component usually contain about 5% or more of extracted molecular substances, resulting in poor spinning properties and poor thread performance. The fiber of the present invention has a conductive component and a non-conductive protective component joined together. The conductive component must have sufficient conductivity, with a resistance of 10 ⁷ Ω.
It is necessary to have a resistivity of less than cm,
It is preferably 10 ⁴ Ω·cm or less, particularly preferably 10 ² Ω·cm or less. Regarding the composite ratio (cross-sectional area occupancy) of the conductive component, a conductive component containing a large amount of conductive carbon black tends to have poor threadability and strong elongation, so it is usually preferably 30% or less, especially 15% or less is suitable. On the other hand, when the composite ratio becomes small, the conductivity becomes unstable or tends to decrease, so it is usually preferably 1% or more, and particularly preferably 3% or more. FIGS. 1 to 3 are specific examples of cross sections (composite structures) of fibers of the present invention. In particular, fibers with a conductive component (A in the diagram, B for the protective component) exposed on the fiber surface, as shown in Figures 1 and 2, have better antistatic performance than core-sheath types as shown in Figure 3. It is particularly preferable as the composite structure of the fiber of the present invention. The fibers of the present invention are in the form of continuous filaments or staples, and can be mixed with other chargeable natural fibers or man-made fibers in an uncrimped or crimped state to impart antistatic performance to textile products. The mixing rate is usually about 0.05 to 10%, but depending on the purpose, of course, a mixing rate of 10 to 100% or 0.05% or less may be applied. The mixing can be performed by any known method such as blending, doubling, twisting, blending, interweaving, interweaving, and other methods. EXAMPLES The present invention will be explained below with reference to Examples. % indicates weight % unless otherwise specified. Examples 1 to 3 Extracted with 1.5 mol% polyethylene glycol (molecular weight 608) copolymerized polyethylene terephthalate 150 parts by weight of powder containing 2.2% of low molecular weight substances, 50 parts by weight of conductive carbon black, and 1 weight of magnesium stearate salt as a fluidity improver. under normal pressure nitrogen flow
4.3% of low molecular weight compounds extracted by melt-kneading three times at 275℃,
A conductive polyester mixture (pellet form) A' having a specific resistance of 7.3 Ω·cm was obtained. Then A′ was placed under a nitrogen stream.
After crystallization drying at 180℃ for 2 hours, the temperature was increased to 230℃.
Solid-phase polymerization was carried out at 0.5 mmHg at 0.degree. C. to obtain conductive polyester compositions A1, A2, and A3 shown in Table 1. Next, A1 is used as a conductive component, and 0.35% titanium oxide is added to polyethylene terephthalate with a molecular weight of 15,000.
The composite structure shown in FIG. 1 was melt-spun using the compound containing (referred to as B) as a protective component. In other words, the composite ratio (volume) of both components in the conductive fiber is 1:
10. The material was spun from an orifice with a diameter of 0.30 mm at a spinning temperature of 290°C, and wound at a speed of 1200 m/min while cooling and oiling. Then, after stretching at 100℃ and 3.19 times, and contacting it with a hot plate at 140℃, 20 denier 6
A drawn filament yarn Y1 was obtained. Similarly A2, A3
The drawn yarns Y2 and Y3 were obtained by melt spinning. Table 1 shows the spinnability and yarn performance of these drawn yarns. The conductivity of the fibers is determined by bundling 60 single threads of 10 cm length and gluing both ends with metal terminals and conductive adhesive.
The resistance value was measured by applying a direct current voltage of 100 volts, and the resistivity of the conductive component calculated from the resistance value was evaluated. The conductivity of the conductive polyester composition (pellet ^form ) is determined by applying a DC voltage (0.1
~1000V) was applied, the resistance value was measured, and the specific resistance calculated from it was evaluated. Next, yarns Y1 to Y3 are each spliced with regular polyethylene terephthalate 50 denier 24 filaments to high-density taffeta (warp/warp density 300 threads/inch) made of regular polyethylene terephthalate 70 denier 36 filaments at 5.1 mm intervals as warp threads. Woven and dyed. The charge amounts of these dyed fabrics are 1.2, 2.5, and 2.2 × 10 ^-6 coulombs/m ² (measured according to the static electricity safety guidelines issued by the Industrial Safety Research Institute of the Ministry of Labor), and the fibers of the present invention Y1~
The fabric mixed with Y3 fully complied with the standard value of 7×10 ^-6 coulombs/cm ² or less of the static electricity safety guideline. Comparative Example 1 Conductive polyester mixture that is not solid phase polymerized
A' was melt-spun and then drawn in the same manner as in Examples 1 to 3 to obtain drawn yarn Y4. The results of Examples 1 to 3 and Comparative Example 1 are shown in Table 1, and as is clear from Table 1, the fibers of the present invention
It was found that Y1 to Y3 had better yarn reeling processability and better yarn performance than the comparative example Y4.

[Table] The yarn breakage rate is the value for a winding amount of 1 kg.
Effects of the Invention The fiber of the present invention is a conductive composite fiber of polyester yarn that has excellent spinning processability and improved yarn performance, and is particularly suitable for polyester fiber products that require dimensional stability, heat resistance, or chemical resistance. It is suitable for mixed use to impart braking performance, and its industrial value is extremely large.

[Brief explanation of drawings]

1 to 3 are specific examples of cross-sectional views of the fibers of the present invention, and FIGS. 1 and 2 are examples of structures in which conductive components are exposed on the fiber surface.

Claims (1)

[Scope of Claims] 1. Consists of a polyester composition in which 60 to 85% by weight of a polyester polymer containing ethylene terephthalate as a main repeating unit and 15 to 40% by weight of conductive carbon black are dispersed by kneading, and then solid-state polymerized. A conductive component and a non-conductive component made of a non-conductive fiber-forming polyester polymer are bonded together, the conductive component contains 4% by weight or less of an extracted low-molecular compound, and the conductive component has a resistance of 10 ⁷ Ω・cm. Conductive composite fibers with a specific resistance of less than 2. The fiber according to claim 1, wherein the extracted low molecular weight substance of the conductive component is 2% by weight or less. 3. The fiber according to claim 1, wherein the non-conductive fiber-forming polyester polymer is polyethylene terephthalate. 4. The fiber according to claim 1, wherein the conductive component occupies an area ratio of 1 to 30% in the cross section of the fiber. 5. The fiber according to claim 1, wherein the conductive component is exposed on the fiber surface in the cross section of the fiber.