JPH05287612A - Conductive acrylic fiber and its production - Google Patents

Abstract

PURPOSE:To obtain the subject fiber not colored black and excellent in the electric conductivity by spinning a dope comprising a non-conductive component and a conductive component which comprises a dope produced by dispersing a conductive agent consisting of specific conductive particles in a matrix polymer having a specific intrinsic viscosity. CONSTITUTION:Acrylonitrile, methyl acrylate, methacrylsufonic acid sodium salt, etc., are radically polymerized to produce an acrylic polymer dope having an intrinsic viscosity of >=1.13 as a matrix. Conductive particles comprising fibrous fine particles having aspect ratios of >=4 are dispersed in the produced matrix to obtain the conductive component. The conductive component is mixed with a non-conductive component in a spinning dope viscosity ratio of <=0.5 between the non-conductive component and the conductive component. The mixture is spun and subsequently subjected to a drawing process, etc., to obtain the objective fiber in which the conductive particles have an X-ray orientation degree of >=90%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excellent conductive acrylic composite fiber, which is used for clothing and construction bedding which requires antistatic effect and electromagnetic wave shielding effect.

[0002]

2. Description of the Related Art Conventionally, as a conductive fiber, for example, a conductive fiber having a core component in which carbon black is dispersed in a polyalkylene glycol copolymer, which is described in Japanese Patent Publication No. 55-23925, is known. However, in order to obtain a conductive fiber having further excellent conductivity, it is necessary to disperse more carbon black which is a conductive particle, and for that purpose, it is necessary to improve the dispersion technique. On the other hand, when carbon black is used, the color of the fiber becomes black, which lacks versatility. Therefore, in order to improve the conductivity, it is necessary to disperse a white conductive component having a more excellent color.
Further excellent conductive particles include silver powder, but since it has a large specific gravity, it tends to settle and is more difficult to disperse, and it is necessary to improve the dispersion technique.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a conductive fiber which uses a general polymer as a matrix and has an excellent conductive color which is not black and has a specific resistance of 10 ² to 10 Ω · cm. It is to provide a method for producing an excellent conductive fiber that is a stand.

[0004]

In the conductive acrylic composite fiber of the present invention, the conductive particles are fibrous with an aspect ratio of 4 or more, and the degree of X-ray orientation in the fibers of the conductive particles is 90% or more. The matrix polymer of the conductive component has an intrinsic viscosity of 1.13 or more.

Further, in the production method of the present invention, the conductive particles are fibrous with an aspect ratio of 4 or more, the degree of X-ray orientation in the fibers of the conductive particles is 90% or more, and the conductive component matrix polymer When producing a conductive acrylic composite fiber having an intrinsic viscosity of 1.13 or more, the spinning dope viscosity ratio of the conductive component and other components is set to 0.5 or less.

Since the conductive fiber of the present invention uses fibrous conductive particles, wet or dry spinning is preferred. In the wet or dry spinning, since the spinning dope is diluted with the solvent, the concentration of the conductive particles is also diluted, so that secondary aggregation can be prevented and a stable dispersion liquid can be prepared. On the other hand, in melt spinning, it is difficult to uniformly disperse the fibrous conductive component because the viscosity of the polymer and the concentration of the conductive particles are high.

The matrix polymer of the conductive component used in the present invention may be a commonly used acrylic polymer.
However, if the polymer is separated from the non-conductive component, the basic performance such as the strength of the fiber is impaired, so that it is necessary to consider the combination of the polymers. The acrylic polymer as the conductive component or the non-conductive component used in the present invention may be a general polymer having acrylonitrile as a main component in terms of composition. That is, methyl acrylate, vinyl acetate, acrylamide, acrylic acid, vinyl chloride, vinylidene chloride or the like can be used as the second comonomer. As the third monomer, sodium allyl sulfonate, sodium methacryl sulfonate, sodium 2-acrylamido 2-methylpropane sulfonate, etc. can be used. The polymerization method of the polymer may be solution polymerization or suspension polymerization, and is not particularly limited.

The conductive component of the composite conductive fiber of the present invention must have physical properties such that it can be spun by itself. Although it is reinforced with a non-conductive component, if it cannot be spun alone, it will have many yarn breakages during spinning of the composite fiber, which is not practical. Since the conductive component contains 30% by weight or more of the conductive particles with respect to the polymer, the polymer concentration becomes 70% or less, which is the usual concentration. When the polymer concentration of the spinning dope is reduced, in an extreme case, the coagulation bath causes insufficient coagulation, which makes it impossible to spin alone. In addition, the conductive particles flow out into the coagulation bath. In order to be able to perform single spinning at a low polymer concentration, the molecular weight of the polymer may be increased. In the present invention, the intrinsic viscosity of the conductive polymer matrix polymer is 1.13 or more, preferably 1.33 or more. If the ultimate concentration is less than 1.13, spinning cannot be performed with only the conductive component, and thus even composite fibers often break. When the intrinsic viscosity is 1.33 or more, yarn breakage during spinning into a composite fiber is almost eliminated, and the fiber strength is also improved. Suspension polymerization is preferable as the polymerization method for increasing the intrinsic viscosity. When dimethylformamide is used in solution polymerization, it is necessary to select the polymerization conditions because dimethylformamide acts as a chain transfer agent.

The acrylic composite conductive fiber of the present invention may be of the side-by-side type or the core-sheath type because the conductive component can be spun alone. In the case of the core-sheath type, it is better that the conductive component is cut off at a part of the core-sheath type sheath to expose the core on the surface. Further, the non-conductive component may include titanium oxide in the sheath portion, for example. When the sheath contains titanium oxide, the coloring of the conductive component of the core is not visible and the appearance is improved. Even after dyeing, it becomes inconspicuous. The composite ratio (weight) of the acrylic composite conductive fiber of the present invention is such that the conductive component is 1 and the non-conductive component is 10 or less. Since the conductivity decreases as the ratio of the conductive component decreases, the ratio is selected according to the required conductivity.
On the other hand, the strength of the composite fiber improves as the ratio of the conductive component decreases. Select an appropriate ratio according to the application.

The conductive particles used in the present invention are 10 ^-1 Ω.
silver-plated conductive potassium titanate with a specific resistance of 1 cm or less,
Fibrous fine particles such as conductive acicular titanium oxide can be used. The aspect ratio of the fibrous fine particles used in the present invention is 4 or more, and 7 or more is preferable because the fibrous fine particles can be easily oriented. 0.1% by weight of particles with a diameter of more than 2μ
If it is above, clogging of the die is likely to occur and the spinnability is deteriorated, which is not preferable in practice. In order to further improve the conductivity, silver-plated fibrous fine particles having a specific resistance of 10 ⁻³ Ω · cm or less are more preferable.

The fibrous fine particles of the present invention can be provided with a degree of orientation of 90% or more by appropriate stretching. If the degree of orientation of the fibrous fine particles is low, good conductivity cannot be imparted to the fibers.

The spinning method according to the present invention may be either wet or dry, but the draw ratio for spinning and drawing is preferably lower than that of ordinary acrylic fibers. A high draw ratio tends to cause cutting of the conductive component, and shrinkage helps repair the cut portion. For example, in wet spinning of acrylic, cotton is produced by spinning, drawing, washing with water, oiling, drying, crimping, and cutting.

[0013]

The conductive fiber of the present invention has a specific resistance of 10 ³
Not only exhibits excellent conductivity of Ω · cm or less, but also has strength of 2
Since it has g / d or more and an elongation of 20% or more and can be used for ordinary fiber applications, it is versatile.

[0014]

EXAMPLES Further details will be described below with reference to examples. In the examples, “%” indicates “weight%”. The strength and elongation of the cotton in the examples was measured according to JIS L-1015. The specific resistance is that silver paste is attached to both ends of a 10 cm long fiber bundle,
The electric resistance was measured and calculated in an atmosphere of 20 ° C. and 60% RH. The X-ray orientation degree H was determined by the following formula from the half width h of the intensity distribution curve along the Debye ring of diffraction of the fibrous conductive component in the fiber. H (%) = [(90 ° -h ° / 2) 90 °] × 100

Example 1 9 acrylonitrile (hereinafter abbreviated as AN), methyl acrylate (hereinafter abbreviated as MA), and sodium methacryl sulfonate (hereinafter abbreviated as MAS) each 9
A monomer concentration of 30% was prepared at a ratio of 6.5, 3, 0.5%, and dimethylformamide was used as a solvent by low temperature polymerization by a conventional method, and a polymer concentration was 18 by radical polymerization using azobisvaleronitrile as an initiator. %, Intrinsic viscosity 1.
15 acrylic polymer dopes for conductive components were obtained. Similarly, at a normal temperature, using azobisisobutyronitrile as an initiator, AN, MA, and MAS were 90, 9.5, 0.
An acrylic polymer dope for a non-conductive component having an intrinsic viscosity of 0.81 at 5% was obtained.

The obtained acrylic polymer dope for the conductive component was used as the conductive component matrix, and the dope in which the conductive agent was dispersed in the ratio shown in Table 1 was used as the conductive component. Wet spinning at a ratio of 3: 1 with the conductive component and 4 times primary drawing,
After washing with water, oiling, crimping and drying, 3 denier 76mm
Got cotton. Among the conductive agents, fibrous conductive fine particles used were whiskers of potassium titanate having an average diameter of 0.5 μm, an average length of 12 μm, a specific resistance of 3 × 10 ⁻² Ω · cm, and 10% by weight uniformly silver-plated. . The degree of orientation of the fibrous conductive particles was 90% or more.

Table 2 shows the specific resistance, strength and elongation of the obtained cotton.

Example 2 20 wt% of fibrous conductive fine particles were silver-plated, average diameter 0.4 μm, average length 3 μm, specific resistance 10 ⁻³ Ω.
-Test No. 1 of Example 1 except changing to needle-shaped titanium oxide of cm. As a result of measuring the specific resistance of the cotton produced in the same manner as in No. 3, it showed excellent conductivity of 9 Ω · cm. The cotton color was also light gray. Malachite green ow of cationic dye
f. Cotton dyed at 1% could be dyed to a slightly dull degree.

Example 3 The intrinsic viscosity of the polymer of the conductive component matrix was 1.3.
No. 8 except that the test No. As a result of measuring the specific resistance of the cotton produced in the same manner as in No. 3, an excellent conductivity of 2 Ω · cm was shown. The strength of this cotton showed a good value of 3.5 g / d. The cotton color was also light gray.

Comparative Example 1 Test No. 1 of Example 1. In the same way as in 3, the primary draw ratio is 2
The doubled cotton had an orientation of 85%. The specific resistance of this cotton was as low as 3.4 × 10 ⁶ Ω · cm and showed low conductivity.

Comparative Example 2 Test No. 1 of Example 1 was conducted using a polymer having a non-conductive component in the conductive component matrix. Spinning was carried out in the same manner as in No. 3, but the fiber breakage occurred frequently during spinning, and the strength of the obtained fiber was also 1 g / d or less. The specific resistance of this cotton was 1.7 × 10 ⁵ Ω · cm, which was a low conductivity.

[Table 1]

[Table 2]

Claims (2)

[Claims] 1. The conductive particles are fibrous with an aspect ratio of 4 or more, the degree of X-ray orientation in the fibers of the conductive particles is 90% or more, and the intrinsic viscosity of the matrix polymer of the conductive component is 1.13. The above is a conductive acrylic composite fiber characterized by the above. 2. The conductive particles are fibrous with an aspect ratio of 4 or more, the degree of X-ray orientation in the fibers of the conductive particles is 90% or more, and the intrinsic viscosity of the matrix polymer of the conductive component is 1.13. A method for producing a conductive acrylic conjugate fiber, characterized in that the spinning dope viscosity ratio of the conductive component and the other component is set to 0.5 or less when producing the conductive acrylic conjugate fiber as described above.