JPH07133510A - Electrically-conductive conjugate yarn - Google Patents

Abstract

PURPOSE:To obtain electrically-conductive conjugate yarn having limited reduction in electrical conductivity even by drawing at a room temperature and excellent color tone. CONSTITUTION:This electrically-conductive conjugate yarn is obtained by bonding an electrically-conductive mixture A of an electricallyconductive carbon black-containing thermoplastic polymer and an electrically-conductive metal compound-containing thermoplastic polymer having compatibility with a polymer to a fiber-forming polymer B and the electrically-conductive mixture A comprises at least part of the fiber surface.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to conductive fibers. More specifically, the present invention relates to a conductive composite fiber that has little deterioration in conductivity even when cold-drawn and has an excellent color tone.

[0002]

2. Description of the Related Art It is well known that fibers, particularly hydrophobic synthetic fibers, are remarkably affected by static electricity due to friction and cause various problems. Many proposals regarding this antistatic have been made so far. One of the effective means is a conductive composite fiber using a thermoplastic polymer in which conductive particles such as carbon black and metal particles are dispersed in a core part and a fiber-forming polymer in a sheath part, which is easily charged with static electricity. There is a method of mixing it in, and it is widely used for work clothes such as carpets.

[0003] In the carpet application, which is the main application of the conductive fiber, the conductive fiber is mixed into the carpet pile by mixing with non-conductive carpet raw fiber, cross twisting, mixing fiber, etc. However, there is a drawback that the process is required and the cost becomes high. Recently, as a simple method of mixing, the undrawn yarn of the conductive composite fiber was introduced into the cooling chimney during the melt spinning of the non-conductive carpet raw fiber, and the carpet raw fiber filament was aligned and drawn on the pulling roll at the same time. Carpet raw fibers containing conductive fibers are manufactured by bulking. In this case, the stretching step is often performed at room temperature (cold stretching), and as a conductive fiber, a conductive polymer using a conductive polymer containing a conductive carbon black that does not significantly decrease in conductivity even when cold-stretched is used. Composite fibers are used.

However, since the carbon black-containing polymer is black, the fibers tend to be black, and particularly when the conductive component is exposed on the surface of the fiber product in order to obtain sufficient antistatic performance, the appearance of the fiber product is remarkably increased. There is a major drawback that it damages, and several proposals have been made to reduce the amount of carbon black mixed in, such as JP-A-57-199817.

On the other hand, as the white conductive fibers, conductive composite fibers mixed with conductive inorganic particles and used for conductive polymers are used, but a large amount of conductive particles ( It is essential to mix it with the polymer (for example 50% by weight or more, especially 70% by weight or more). for that reason,
When stretched at room temperature, the polymer is severed and the conductivity decreases or disappears remarkably, which is not suitable for the above-mentioned conductive fiber mixing method.

[0006]

DISCLOSURE OF THE INVENTION The object of the present invention is to adapt to the recent simplified method for mixing conductive fibers, and the conductive composite fibers exhibit little deterioration in conductivity even when cold-drawn and are excellent in color tone. Is to provide easily.

[0007]

[Means for Solving the Problems] That is, the present invention relates to a thermoplastic polymer P1 containing a conductive carbon black.
A conductive mixture A of a thermoplastic polymer P2 containing conductive metal compound particles and having compatibility with P1 and a fiber-forming polymer B are joined together, and the conductive mixture has a fiber surface in a cross section of the fiber. The conductive composite fiber is characterized by occupying at least a part thereof.

In the present invention, the conductive carbon black means one having good conductivity among carbon blacks such as acetylene black, channel black, furnace black, thermal black and Ketjen black, and its volume resistivity is It is preferably 10 ¹ Ωcm or less, preferably 10 ⁰ Ωcm or less, and more preferably 10 ^-1 Ωcm or less.

As the white conductive metal compound particles used in the present invention, any kind of particles can be used as long as the powdery volume resistivity is about 10 ⁴ Ωcm or less.
Particles and metal compounds having a high whiteness metal oxide film are most preferable, but metal powder (for example, silver, nickel,
Copper, iron, alloys thereof, etc.), metal compounds such as copper sulfide, copper iodide, zinc sulfide, cadmium sulfide and the like, which are slightly inferior in color tone, may also be used.

Examples of the metal oxide particles include particles of tin oxide, zinc oxide, copper oxide, cuprous oxide, indium oxide, zirconium oxide, tungsten oxide and the like. Most of the metal oxides are semiconductors close to insulators. For example, a suitable second component (impurity) is added in a small amount, usually 50% or less, and often 25% or less.
It is possible to obtain one having enhanced conductivity and having sufficient conductivity for the purpose of the present invention. As such a conductivity enhancer, antimony oxide can be used for tin oxide, and metal oxides such as aluminum, indium, germanium, and tin can be used for zinc oxide. Further, particles in which a conductive film of the above metal oxide or metal compound is formed on the surface of non-conductive inorganic material particles such as titanium oxide, zinc oxide, magnesium oxide, tin oxide, iron oxide, silicon oxide, aluminum oxide are also used. . Among them, titanium oxide is preferable because it is excellent in whiteness and has a small particle size and uniform particles can be obtained.

With respect to the conductivity of the white conductive particles, the volume resistivity in powder form is preferably about 10 ⁴ Ωcm or less, more preferably about 10 ² Ωcm or less, most preferably about 10 ¹ Ωcm or less. Actually, a material having a conductivity of about 10 ² to 10 ⁻² Ωcm can be obtained and can be suitably applied for the purpose of the present invention, but a material having more excellent conductivity is more preferred.

In order to prevent coloring of the particle compound,
It is also effective to make the particle diameter of the conductive particles equal to or smaller than the wavelength of light. From the viewpoint of spinnability, those having an average particle size of 1 to 2 μm are not unusable, but usually those having an average particle size of 1 μm or less, particularly 0.5 μm or less, most preferably 0.3 μm or less are used.

The mixing ratio of the carbon black particles of the conductive polymer P1 varies depending on the properties of the binder polymer to be mixed, the type of crystal or carbon black particles, the shape of the conductive particles, the particle size, etc. weight%
It is within the range of about 30 to 40% by weight. If it is less than 15% by weight, it is near the percolation threshold and the conductivity is unstable. Again, 4
When it exceeds 5% by weight, it becomes difficult to uniformly disperse the carbon black particles in the polymer, and even if the carbon black particles can be dispersed, the fluidity of the polymer is lowered, which is not preferable from the viewpoint of spinnability. The conductivity of the polymer P1 is preferably a compound and has a volume resistivity of 10 ⁴ Ωcm or less, and preferably less than 10 ² .

The mixing ratio of the white conductive particles to the conductive polymer P2 varies depending on the kind of particles, conductivity, particle size, chain forming ability of particles, and the nature and crystallinity of the binder polymer to be mixed, but usually. It is in the range of about 10 to 85% by weight, often about 30 to 80% by weight, and particularly preferably 50 to 80% by weight. The specific resistance (volume resistivity) of the conductive polymer P2 needs to be less than 10 ⁶ Ωcm, preferably 10 ⁴ Ωcm or less, particularly preferably 10 ² Ωcm or less.

It is essential that the thermoplastic polymer mixed with the conductive carbon black particles or the white conductive particles to form the conductive component has compatibility. Other than that, it is not particularly limited and can be arbitrarily selected. Examples include numerous thermoplastic polymers such as polyamides, polyesters, polyolefins, polyvinyls, and polyethers. This polymer is preferably a fiber-forming one from the viewpoint of spinnability, but even if it is inferior in spinnability, a composite fiber can be obtained by using a fiber-forming polymer as the non-conductive component to be combined. Among such polymers, polymers having a crystallinity of 60% or more, which has a poor affinity with the fiber-forming non-conductive polymer, are preferable, and examples of such polymers include polyethylene, polypropylene, polyoxymethylene, polyethylene oxide and the like. Derivatives (eg block copolymers of polyethylene oxide PET),
Examples thereof include polyvinyl alcohol and polycaprolactone. Of these polymers, polyethylene is particularly suitable.

The conductive polymers P1 and P2 further have dispersibility (for example, waxes, polyalkylene oxides, various surfactants, organic electrolytes, etc.), colorants, pigments, stabilizers (antioxidants, ultraviolet absorbers). Etc.), fluidity improver,
Other additives can be added.

The mixture A in the present invention is preferably prepared by mixing the conductive polymers P1 and P2 during spinning. For example, there are a method of mixing with a static type kneading element provided in a polymer flow path in a spinning pack, a method of mechanically kneading with a single-screw extruder, and the like.

The reason why such a mixture makes it possible to carry out cold stretching (conductivity does not disappear) is that P2 alone gives a white color, but the polymer is cut by cold stretching, that is, the chain structure of the conductive particles is destroyed and the conductivity is reduced. However, due to the incorporation of P1, the chain structure of which is difficult to be destroyed even by cold stretching, P1 acts to compensate for the voids of P2, and as a result, the electrical conductivity is reduced by cold stretching, but it does not disappear. It is supposed not. According to the examination results of the present inventors,
The amount of the polymer P1 mixed in the conductive mixture A is P1.
Although it is not particularly limited depending on the concentrations of carbon black and conductive metal compound particles in P2 and P2, it is usually in the range of 10 to 50% by weight, and particularly preferably about 30 to 40% by weight. If it is less than 10% by weight, cold stretchability is hardly exhibited,
When it is 50% by weight or more, it is difficult to maintain the white color, which is not preferable.

On the other hand, as the fiber-forming polymer B of the composite fiber, any spinnable fiber is used. Among them, nylon 6, nylon 66, nylon 12, nylon 6
Polyamide such as 10, polyethylene terephthalate,
Polyester such as polyethyleneoxybenzoate, polybutylene terephthalate, polyacrylonitrile,
Polypropylene and copolymers and modified products of these polymers are particularly preferable. If desired, known additives such as matting agents, pigments, colorants, stabilizers, antistatic agents (polyalkylene oxides, various surfactants, etc.) can be added to the fiber-forming polymer.

In the composite fiber of the present invention, the conductive mixture A
The composite ratio (cross-sectional area occupancy rate) is arbitrary, but is usually 3 to 50.
%, Especially 5-30% and most often 7-20%. When the compounding ratio is less than 3%, the conductivity is lowered or becomes unstable, while when it exceeds 50%, the yarn quality is deteriorated.

The cross section (contour) of the conjugate fiber of the present invention may be circular or non-circular and is not particularly limited, but it is essential that the mixed component A occupies at least a part of the fiber surface. 1 and 2 are examples of cross-sections of composite fibers suitable for the present invention.

[0022]

The present invention will be described in more detail with reference to the following examples. Unless otherwise specified,% indicates a weight ratio. In the examples, the antistatic performance and the conductive performance were evaluated by the weight ratio by the following method. Antistatic property is JIS No. L109
4 (1988) reference method and evaluated by the following methods. Normal 6 nylon drawn yarn (210 denier / 54
(Filament) is knitted using a circular knitting machine, in which case 1
A conductive knitted fabric is knitted at intervals of 1 turn to 0 turn to form a circular knitted fabric with a mixing ratio of 0.85%. After the spinning oil is removed by refining, it is thoroughly washed, dried at 80 ° C. for 3 hours, and then conditioned at 25 ° C. and 20% RH for 24 hours. Then, the charged voltage was measured and evaluated immediately after rubbing 15 times with a cotton cloth in the same temperature and humidity. Conductivity is calculated by bundling 10 cm long gut or 5 single yarns, adhering 0.5 mm square aluminum foil to both ends with conductive adhesive, applying a DC voltage of 1 kV and measuring the resistance value. The volume resistivity of the conductive component was evaluated. The color tone was evaluated by the L value using a Hunter color difference meter.

Example A pale grey-blue average particle size of 0.25 μm, specific resistance of which was obtained by mixing and firing 1.5% of antimony oxide with titanium oxide particles having a tin oxide film of 15% on the surface. 0 Ωcm
The conductive powder of is referred to as A1. Molecular weight about 16,000, melting point 215 ° C, nylon 6 with conductive carbon black 3
5% mixed and dispersed conductive polymer was CP1, 75% of the above conductive powder A1 was mixed and dispersed CP2, and 5% titanium oxide particles were dispersed as a matting agent, and NP1 was used as the polymer. To do.

CP1 is a conductive polymer P1 and CP2 is P
2. Using NP1 as the B component, composite melt spinning was performed with a composite ratio and a cross-sectional shape as shown in Table 1. The melt-composited components were spun at a spinning temperature of 270 ° C. from an orifice having a diameter of 0.25 mm, and cooled and oiled at 600 m / mi.
n. It was wound up at the speed of. Then draw in a greenhouse at a draw ratio of 3.0
Drawn with 40 denier / 8 filament Y1
Got Stretched yarns Y2 to Y7 were obtained in the same manner as in Example 1 except that the compounding ratio of CP1 in the conductive component A, the composite ratio, and the fiber cross-sectional shape were changed. Table 1 shows the measurement results of the volume resistivity of these electroconductive composite fibers in the undrawn state, the volume resistivity of the drawn yarn, the friction electrostatic voltage and the color tone.

[0025]

[Table 1]

The yarns Y1, Y2, and Y4 to Y7 all showed little decrease in conductivity due to drawing, and the drawn yarn also showed good conductivity of 10 ⁴ Ωcm or less, but Y3 showed conductivity due to drawing. The sex decline was remarkable. Anti-static performance is Y1,
Y2Y4 and Y5 had a friction band voltage of 2.5 kV or less, which was a good value, but Y3 having low conductivity and Y6 in which the conductive component was not exposed on the fiber surface had poor antistatic property. In addition, ordinary 6 nylon drawn yarn (210 denier /
The electrification voltage measured with a circular knitted fabric consisting of only 54 filaments was 12.5 kV. Also, in terms of color tone, Y4, Y
Y5, which had a high degree of exposure of 7 and the mixed component A to the fiber surface, was white or off-white.

CP1 was used alone as the conductive component, Y8 was obtained in the same manner as in Example 1, and Y9 was obtained by using CP2 alone. Table 1 shows the evaluation results similar to those of the examples. Y8 was excellent in conductivity and antistatic property, but the coloring of the fiber was large, and
Y9 had a remarkable decrease in conductivity due to stretching and was inferior in antistatic performance.

[0028]

EFFECTS OF THE INVENTION With the yarn of the present invention, a bulked yarn used for a carpet containing white conductive fibers and a normal yarn for woven or knitted fabric can be easily produced by a usual yarn producing method without requiring a special mixing method. Therefore, it is possible to reduce the cost in the production of antistatic textile products.

[0029]

[Brief description of drawings]

FIG. 1 is an example showing a cross-sectional shape of a conductive composite fiber suitable for the present invention.

FIG. 2 is an example showing a cross-sectional shape of a conductive composite fiber suitable for the present invention.

FIG. 3 is an example showing a cross-sectional shape of a conductive composite fiber suitable for the present invention.

FIG. 4 is a comparative example used to show the superiority of the present invention.

[Explanation of symbols]

A mixed component of carbon black-containing conductive polymer P1 and metal compound-containing white conductive polymer P2 B fiber-forming polymer

Claims (3)

[Claims] 1. A conductive mixture A of a thermoplastic polymer P1 containing a conductive carbon black and a thermoplastic polymer P2 containing conductive metal compound particles and having compatibility with the P1, and a fiber-forming polymer B. Are joined together, and the conductive mixture A occupies at least a part of the fiber surface in the cross-section of the fiber. 2. The conductive mixture A comprises 10 to 50% by weight of P.
The fiber of claim 1 comprising 1 and 90-50% by weight P2. 3. The electrically conductive mixture A, in a fiber cross section,
The fiber according to claim 1, which occupies 7 to 20% or less of the cross-sectional area.