JPS6317950B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing conductive fibers containing cuprous iodide as a conductive substance. Synthetic fibers such as polyester fibers and polyamide fibers have low conductivity, so static electricity is generated due to friction. Fabrics made of such synthetic fibers are
During use, a high electrical potential of 10 K.V. or more is observed, causing various problems due to dust adhesion and discharge. In addition, semi-synthetic fibers, natural fibers,
For example, acetate, silk, wool, etc. have hygroscopic properties and therefore have relatively fewer problems due to triboelectrification than synthetic fibers, but they are still similar to synthetic fibers in low humidity environments, for example. becomes charged and becomes a problem. In order to solve this problem, it is known to mix conductive fibers into textile products, and conductive fibers include metal fibers, 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 they break when bent during use or processing, resulting in a decrease in conductive performance.They are also difficult to mix with other fibers, inter-knit, or inter-weave, and also have metal-specific properties. It has many drawbacks such as having a different color tone. Metal-plated fibers require a uniform and continuous plating layer to be formed on the fiber surface, which requires smoothness on the fiber surface, which greatly limits the types of fibers that can be applied. It has to be applied with precision, resulting in extremely high manufacturing costs, low durability because the plating layer easily peels off during use or processing, and furthermore, it has many disadvantages, such as exhibiting a color tone peculiar to metal. have. Fibers coated with a polymer dope containing a conductive substance also have the same drawbacks as the above-mentioned metal-plated fibers in terms of manufacturing cost, peeling, and the like. Furthermore, in order for carbon black-containing fibers to exhibit electrical conductivity, it is necessary to incorporate 15% or more of carbon black into the polymer, and special measures such as composite spinning are required in the spinning process. It has drawbacks such as high manufacturing cost, inability to apply to natural fibers, and inability to remove the black color of carbon black. The present inventor has developed a conductive fiber that does not have the above drawbacks in Japanese Patent Application No. 54-15035 (Japanese Unexamined Patent Publication No. 54-15035).
107504). Such conductive fibers are produced by adsorbing iodine onto organic fibers (hereinafter referred to as fibers) and absorbing the iodine into the fibers, and then treating with an aqueous solution of a cuprous compound to precipitate cuprous iodide inside the fibers. In the cross section of the fiber, cuprous iodide exists at least in the outer peripheral surface layer, and the electrical resistance under a DC voltage of 1 KV is 1×10 ¹² Ω/cm or less, which can exhibit conductivity. It is. However, if conductive fibers are repeatedly manufactured by this method and treated with an aqueous solution of a cuprous compound three to four times, the resulting fibers will have lower conductivity and will be colored dark green. I learned that it would be like this. As a result of intensive studies in an attempt to eliminate such drawbacks, the present inventor discovered that as the number of times of treatment with an aqueous solution of a cuprous compound is increased, the concentration of cuprous ions in the treatment solution decreases. It was discovered that by-product accumulation of cupric ions, which cannot react with iodine, occurs in the treatment solution, and that this colors the fibers. I learned that it is possible to dramatically increase the number of processing times. However, it has been found that even if copper metal is present in the treatment liquid in this way, the conductive performance of the resulting fibers deteriorates when the treatment is repeated further. As a result of extensive studies aimed at further increasing the number of processing times, the inventor has found that
The present invention was completed based on the knowledge that the number of treatments could be further increased by replacing the inside of the treatment apparatus with nitrogen gas at the same time as making copper metal exist in the treatment solution. That is, in the present invention, organic fibers in which iodine has been absorbed are treated in an aqueous solution of a cuprous compound in which copper metal is present in a nitrogen atmosphere, and an amount that exhibits conductivity is added to the fibers. This is a method for producing conductive fibers characterized by depositing cuprous iodide. The term "absorption" used in the present invention refers to adsorbing iodine to fibers and absorbing it into fibers as described above. The process of allowing the fibers to absorb into the fibers is sometimes referred to as adsorption. The fibers that serve as the base of the conductive fibers in the present invention are:
Any organic fiber may be used, such as polyester fibers such as polyethylene terephthalate and polybutylene terephthalate, 6-nylon,
66 - Polyamide fibers such as nylon, vinyl polymer fibers such as polyacrylonitrile and polyvinyl alcohol, synthetic fibers such as wholly aromatic polyamides and wholly aromatic polyesters, semi-synthetic fibers such as acetate, silk and wool. Natural fibers such as In the present invention, such fibers are made to contain cuprous iodide to impart electrical conductivity, and the amount of cuprous iodide to be deposited is determined by the electrical conductivity of the fibers at a DC voltage of 1 K.V. An appropriate amount is such that the resistance is 1×10 ¹² Ω/cm or less. The specific value of this amount varies greatly depending on the type and shape of the fiber, especially depending on the type, and cannot be determined unconditionally. For example, polyethylene terephthalate fibers usually require a content of 2% by weight or more, while nylon 6 fibers require a content of 50% by weight or more. In order to precipitate cuprous iodide on fibers, iodine is first adsorbed onto the fibers, and then the fibers are treated in an aqueous solution of a cuprous compound. Any method can be used to adsorb iodine onto the fibers. Examples include a method of immersing the fibers in an aqueous or organic solvent solution of iodine, and a method of exposing the fibers to an iodine gas atmosphere. Among them,
The method of immersion treatment in an iodine aqueous solution is the simplest and preferred. To prepare an iodine aqueous solution, it is preferable to use iodide as a solubilizing agent, as iodine is difficult to dissolve in water.In some cases, a fiber swelling agent may also be used to facilitate the adsorption of iodine. It's okay. Examples of the iodide used as a solubilizing agent include potassium iodide, sodium iodide, lithium iodide, ammonium iodide, and hydrogen iodide. The conditions for adsorbing iodine onto fibers, that is, the iodine concentration in the iodine aqueous solution, the solution temperature, and the treatment time, vary greatly depending on the type of fiber, and also vary depending on the shape, particularly the fineness of the single fibers, and cannot be specified unconditionally. In addition, the amount of iodine to be adsorbed to the fibers is determined by the amount of cuprous compound in order to precipitate a sufficient amount of cuprous iodide to impart conductivity to the fibers by treatment with a cuprous compound aqueous solution, which will be described later. Although it varies slightly depending on the processing conditions of the aqueous solution,
Usually, 2% by weight or more is required, and the iodine adsorption treatment conditions may be adjusted accordingly. For example, add 60 parts by weight of iodine and 40 parts by weight of potassium iodide to 100 parts by weight of water.
When a 6-nylon fiber with a single filament fineness of 30 denier is immersed in an aqueous solution of iodine dissolved in iodine at room temperature, the amount of iodine adsorbed reaches approximately equilibrium after 10 minutes, and the weight increase due to iodine adsorption is approximately 190%. When heated to 80°C, the 6-nylon fibers swell significantly and begin to decompose. However, when polyethylene terephthalate fibers with a single filament fineness of 30 denier are immersed in an iodine aqueous solution with the same composition, almost no iodine is adsorbed even after several hours at room temperature, and about 40% is adsorbed after 2 hours at 80°C.
Weight increase due to iodine adsorption is observed. Fully aromatic polyamide fibers (for example, made of metaphenylene diamine and isophthalic acid) are similar to 6-nylon fibers in that they have amide groups that have good affinity for iodine, but their chemical structure is more rigid. Therefore, iodine adsorption conditions similar to or more severe than those for polyethylene terephthalate fibers are required. In other words, in general, fibers with a relatively loose chemical structure easily adsorb iodine and can quickly and in large quantities even at room temperature, whereas fibers with a rigid chemical structure have difficulty adsorbing iodine and can absorb iodine at higher concentrations. Therefore, a higher temperature iodine aqueous solution is required. For example, wool, silk,
Acetate fibers, polyvinyl alcohol fibers, polyacrylonitrile fibers, 6-nylon fibers, etc. belong to the former category, and for example, polyethylene terephthalate fibers, wholly aromatic polyamide fibers, etc. belong to the latter category. Further, even if the type of fiber is the same, as the fineness of the single fiber increases, the rate of iodine adsorption tends to decrease. To prepare an aqueous cuprous compound solution used to treat iodine-adsorbing fibers to form cuprous iodide in the fibers, the cuprous compound can be simply dissolved in water; Examples of the cuprous compound include cuprous chloride, cuprous bromide, cuprous sulfite, etc. Among them, cuprous chloride is preferred from the viewpoint of ease of availability and handling. Further, when preparing the cuprous compound aqueous solution, it is preferable to use a solubilizing agent together. For example, when cuprous chloride is used as a cuprous compound, if a water-soluble salt such as hydrochloric acid, ammonium chloride, sodium chloride, or potassium chloride is used as a solubilizing agent in combination, the concentration of chloride ions in the treatment solution can be increased. This increases the solubility of cuprous chloride and increases the concentration of cuprous ions in the solution, thereby increasing treatment efficiency. Furthermore, depending on the type of fiber, an organic solvent or a surfactant may be added to the treated fiber to swell the treated fiber, promoting penetration of cuprous ions into the fiber, and reducing iodine by reaction with adsorbed iodine within the fiber. It is also possible to smoothly form cuprous oxide. The treatment conditions using a cuprous compound aqueous solution, that is, the concentration of cuprous compound in the treatment solution, solution temperature, and treatment time, vary greatly depending on the type of iodine-adsorbing fiber to be treated, and the iodine adsorbed on the fiber Although it cannot be specified unconditionally because it varies depending on the amount, the optimum conditions can be easily determined by experiment. For example, cuprous ions are relatively easy to penetrate6
- For nylon fibers, 0.2 to 0.3 mol/1 chloride
If an aqueous copper solution is used, the iodine adsorbed in the fibers will almost completely react to become cuprous iodide by immersion treatment at room temperature for about one hour. On the other hand, for polyethylene terephthalate fibers, which have a relatively low affinity for cuprous ions and water, if a cuprous chloride aqueous solution with the above composition is used, dipping treatment at room temperature would require an extremely long treatment time. However, the processing time can be shortened to about 1 hour by keeping the liquid temperature at about 45°C.
In addition, even with fully aromatic polyamide fiber, the liquid temperature can be reduced to 70°C.
If the treatment is carried out to a certain extent, the treatment can be carried out in about one hour using a treatment liquid having the above composition. In the present invention, when treating the iodine-adsorbing fibers with the cuprous compound aqueous solution, copper metal is present in the cuprous compound aqueous solution and the treatment is carried out under a nitrogen atmosphere. For example, polyethylene terephthalate fibers that have adsorbed iodine are
If the treatment with an aqueous copper solution is carried out in the absence of copper metal and in an air atmosphere, the fibers obtained after 3 to 4 treatments will have reduced conductivity or will be colored dark green. On the other hand, if copper metal is present, the number of treatments can be dramatically increased, but even then, after more than 20 treatments, the conductivity of the resulting fibers will decrease. Also,
If copper metal is not present and the treatment atmosphere is replaced with nitrogen gas, the fibers obtained after 5 to 6 treatments will have reduced conductivity or will be colored dark green. However, if copper metal is present in the treatment solution and this treatment is carried out under a nitrogen atmosphere, the conductivity of the fibers obtained will not decrease even after more than 30 treatments, and no coloration will occur. That is, the synergistic effect of the presence of copper metal and the nitrogen atmosphere makes it possible to greatly increase the number of times the cuprous compound aqueous solution is treated. The shape of the copper metal present in the cuprous compound aqueous solution may be arbitrary, but shapes with a large surface area, such as foil (film, sheet) shape, linear shape, powder grain shape, are preferable, depending on the shape of the fibers to be treated. For example, foil (film,
Sheet) and linear shapes are preferred. The amount of copper metal used depends on its surface area and cannot be specified with certainty, but it is usually used in excess, and secondary metal is added to the processing solution.
If copper ions increase, more may be added. Further, this copper metal may be constantly present in the cuprous compound aqueous solution, or may be temporarily present only when cupric ions are generated in the cuprous compound aqueous solution. According to such a manufacturing method of the present invention, conductive fibers in which cuprous iodide is present at least in the outer peripheral surface layer within the fiber cross section can be obtained extremely efficiently, and such conductive fibers have a 1KV The electrical resistance under direct current voltage is 1×10 ¹² Ω/cm or less, and the durability of this conductive performance is extremely superior compared to conventional conductive fibers in which conductive substances are attached to the fiber surface. There is. Moreover, the conductive fibers obtained by the production method of the present invention are white to pale yellow, and the color tone is significantly better than that of conventional conductive fibers. The present invention will be explained in further detail by giving examples below.
In addition, the electrical resistance in the examples is based on the relative humidity of the sample.
After being left in a 65% atmosphere for 6 hours, the electrical resistance values at five arbitrary locations were measured. Comparative Example 1 Polyethylene terephthalate multifilament of 75 denier/24 filaments was knitted into a tube using a stockinette knitting machine, 100 g of this fabric was loosely wrapped around a stirring blade, and 4600 g of iodine and 5000 g of potassium iodide were added.
was immersed together with a stirring blade in an aqueous solution of iodine at 70°C dissolved in 10 parts of water, rotated at a speed of 30 rpm for 1 hour, washed with water, left overnight to air dry, and adsorbed 135 g (35% weight increase) of iodine. I got the cloth. Divide this fabric into 5 equal parts, each weighing 27g,
Wrap one piece loosely around the stirring blade, and
g and 85 g of ammonium chloride were dissolved in 1 part of water.
Nonionic detergent score roll after being immersed in copper chloride aqueous solution at 55°C and rotated at a speed of 30 rpm for 1 hour.
400 (manufactured by Kao Atlas Co., Ltd.) and 20 g of ammonium chloride were added for 30 minutes in boiling water for 30 minutes, washed with water, and dried. The resulting treated fabric was unwound and wound onto a bobbin. The remaining iodine adsorption samples were sequentially treated in the same manner using the copper chloride aqueous solution after the above treatment, and then unwound and rolled up. Table 1 shows the electrical resistance value at 1 K.V. of each multifilament in the treatment system obtained, the weight increase rate compared to before iodine adsorption, the color tone, and the hue of the treatment solution before each treatment.

[Table] A green film-like floating substance was generated, and as the number of treatments increased, the number of floating substances increased.
Comparative Example 2 Iodine was adsorbed to 10 pieces of 20 g of knitted tubes obtained by knitting the same polyethylene terephthalate as in Comparative Example 1, and the weight increase rate was 32 to 35%.
An iodine adsorption sample was prepared. Next, the same cuprous chloride water chloride as in the comparative example was added.
A copper aqueous solution was prepared, and this aqueous solution was treated 10 times in sequence in the same manner as in Comparative Example 1, except that it was kept under a nitrogen gas atmosphere at all times during the treatment, and then unwound and rolled up. The results were as shown in Table 2.

[Table] A green film-like floating substance was generated, and as the number of treatments increased, the number of floating substances increased.
Comparative Example 3 Iodine was adsorbed to 25 pieces of 20 g tubular knitted fabric obtained by stockinette knitting the same polyethylene terephthalate as in Comparative Example 1, and the weight increase rate was 32 to 35.
% iodine adsorption samples were prepared. Next, the same cuprous chloride aqueous solution as in Comparative Example 1 was prepared, and the copper wire with a surface area of 600 cm ² was kept immersed in it at all times, but it was sequentially treated, unwound, and rolled 25 times in the same manner as in Comparative Example 1. The results are shown in Table 3.

【table】

[Table] Example 1 Iodine was adsorbed to 35 pieces of 20 g tubular knitted fabric obtained by stockinette knitting the same polyethylene terephthalate multifilament as in Comparative Example 1, and the weight increase rate was 32 to 35%. An iodine adsorption sample was prepared. Next, the same cuprous chloride aqueous solution as in Comparative Example 1 was prepared, and before each treatment, a copper wire with a surface area of 600 cm ² was immersed for 60 minutes, and this aqueous solution was constantly immersed in nitrogen gas during the treatment and between each treatment. The material was treated 35 times in sequence in the same manner as in Comparative Example 1 except that it was placed in an atmosphere, and then it was unwound and rolled up. The results were as shown in Table 2.

【table】

Claims (1)

[Claims] 1. An organic fiber in which iodine has been absorbed into the fiber is treated in an aqueous solution of a cuprous compound in which copper metal is present in a nitrogen atmosphere, and an amount of cuprous iodide that exhibits conductivity is added to the fiber. A method for producing conductive fibers, characterized by precipitating.