JPH11158746A - Production of surface-metallized fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the subject fiber with an electromagnetic wave-shielding capability, excellent in flexibility and useful for e.g. clothes by making glucose adhere to polyamide fiber in process of etching and forming silver film thereon under a specific condition. SOLUTION: This fiber is obtained by treating a polyamide fiber of e.g. nylon 6 with a glucose-containing acid e.g. acetic acid, making the glucose adhere to the surface of the fiber along with etching it and contacting it with a silver nitride-containing ammonia aqueous solution to form a silver film on the surface of the fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing surface metallized fiber which can be suitably used as a material for shielding electromagnetic waves radiated from OA equipment and the like, and is particularly used for clothing. The present invention relates to a method for producing a surface metallized fiber which is flexible so that it can be used for weaving and knitting together with polyester, acrylic, and nylon fibers, and has excellent electromagnetic wave shielding performance.

[0002]

2. Description of the Related Art Clothes used for shielding electromagnetic waves radiated from OA equipment and the like include cloth woven with thin metal wires such as copper and stainless steel, cross-woven cloth such as carbon fiber, and carbon black. In addition, conductive rubber and plastic sheet mixed with metal powder are known, but these fabrics have respective problems and cannot be said to sufficiently satisfy the requirements.

[0003] In other words, in a fabric in which fine metal wires are woven, there is a problem in that the metal wires are cut during use, the cut ends protrude from the surface of the fabric, and touch the skin to cause discomfort. In addition, the electromagnetic wave shielding properties of the carbon fiber cross-woven fabric are insufficient, and the metallic rubber and plastic sheet mixed with the metal powder also have insufficient electromagnetic wave shielding properties.
There is also a problem that the texture of the fabric is coarse and hard and can be used only for limited uses such as aprons.

To solve such a problem, Japanese Patent Laid-Open No.
Japanese Patent Publication No. 221549 proposes a cloth made of a synthetic fiber multifilament having fine granular irregularities and fine wrinkle-like irregularities on its surface, which is metal-coated by an electroplating method or a sputtering method. However, the fabric does not have a sufficiently uniform metal film and has poor electromagnetic wave shielding properties, and is coated in a fabric state. It was damaged and the texture as a woven or knitted fabric was reduced, making it unsuitable for clothing.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and provides a method for producing surface metallized fibers which can be suitably used as a material for shielding electromagnetic waves radiated from OA equipment and the like. It provides a method.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, prior to forming a silver film on the surface of polyamide fiber by an electroless plating method utilizing a silver mirror reaction, reduction was carried out. It was clarified that when the fiber surface was etched with an acid containing glucose as an agent, glucose was firmly adhered to the fiber surface, the strength of the film was increased, and a polyamide fiber having excellent electromagnetic wave shielding properties was obtained.

Thus, according to the present invention, a polyamide fiber is treated with an acid containing glucose, and the surface of the fiber is etched and glucose is simultaneously attached to the surface of the fiber.
Then, a method for producing a surface metallized fiber is provided, which comprises contacting an aqueous ammonia solution containing silver nitrate to form a silver film on the fiber surface.

Hereinafter, the present invention will be described in detail. Polyamide fiber is used as the base fiber used in the method of the present invention. As the polyamide fiber, not only aliphatic polyamide fiber such as nylon 6 and nylon 66 but also aromatic polyamide fiber such as aramid fiber can be used. .

That is, the cloth using the surface metallized fiber is subjected to the same finishing processing as that of the ordinary clothing cloth, and in this case, the cloth is mixed with polyester fiber, polyamide fiber, and acrylic fiber to reduce the alkali weight and perform dyeing. Often processed. Therefore, the surface metallized fiber needs properties such as chemical resistance and heat resistance, and nylon 66 is the most excellent in this regard. That is, it is optimal to use nylon 66 fiber as a base fiber and chemically plating silver on the surface thereof.

The form of the polyamide fiber used as the base material is not particularly limited, and any form can be used. That is, in addition to monofilament yarns and multifilament yarns in which fibers are straight, various crimped forms, for example, false twisted yarns may be used, and further, knitted into a knitted fabric A processed yarn having a form such as knit / de-knit obtained by later knitting may be used.

Usually, the surface of the polyamide fiber is extremely smooth, and its adhesion and adhesion are poor when a silver film is formed. Therefore, a fine uneven structure is formed on the fiber surface (hereinafter referred to as etching).
It is necessary. In the present invention, the etching is performed by treating the fiber surface with an acid, and examples of the acid used include formic acid, acetic acid, and nitric acid.

Further, in the present invention, it is important that glucose (glucose) is previously contained in the acid as a reducing agent. When a substance other than glucose is used as the reducing agent, decomposition occurs when used in combination with an acid, and the effect of the present invention is not exhibited.

That is, when glucose is used, its properties can be maintained without being decomposed even in an acid solution, so that the treatment can be performed in the same bath as the acid, and the etching and the attachment of the reducing agent are performed simultaneously. be able to. By simultaneously performing the etching and the attachment of the reducing agent in this manner, the reducing agent is uniformly and firmly attached to the surface of the polyamide fiber, and a uniform and strong silver film can be formed.

Next, when the polyamide fiber thus treated is brought into contact with an aqueous ammonia solution containing silver nitrate, metallic silver precipitates on the surface of the polyamide fiber to form a film. If necessary, it is further contacted several times with an alkaline solution containing silver to deposit a silver film on the surface of the polyamide fiber by a reduction reaction.

Here, as a method of bringing the fiber into contact with an aqueous solution of ammonia containing silver nitrate, a conventionally known method can be arbitrarily adopted. A preferred example is a so-called spray method in which an aqueous ammonia solution containing is sprayed.

At this time, the speed of silver film formation greatly affects the silver film characteristics of the obtained surface-metallized fiber. That is, in order to form a more uniform silver film on the fiber surface, it is important that the yarn is run at a constant speed and brought into contact with an aqueous ammonia solution containing silver nitrate so that the contact time is constant. Thus, a silver film having extremely high uniformity can be formed.

If the running speed is too high, the reduction reaction in the liquid is not completed, and the reduction reaction is completed in air after the contact treatment. When the silver film is formed in the air as described above, silver becomes large granular crystals, and it is difficult to form a uniform silver film. Therefore, the contact time is desirably at least 15 minutes in order to form a silver film of fine crystals as dense as possible. The contact treatment can be performed by a plurality of steps.

The surface-metallized polyamide fiber thus obtained is a good conductor of electricity. For example, when it is used in a state where it is woven in a grid at regular intervals in a fabric made of fibers usually used for clothing, It exhibits good electromagnetic wave shielding performance.

[0019]

The present invention will be described in more detail with reference to the following examples. In addition, the electromagnetic wave shielding property in an Example is measured by the following method.

(1) Near-field electromagnetic wave shielding: MIL-
Performed by a method based on STD-285. That is,
Cloth (20c) to be measured between antennas in a shield box (TR17301A; manufactured by Advantech) in which a transmitting antenna and a receiving antenna are installed in a short distance
(m × 20 cm), and transmits with changing the frequency in the range of 100 Mhz to 1 Ghz, and the attenuation state at each frequency is measured by a spectrum analyzer with a tracking generator (R-3361A; manufactured by Advantech).

(2) Radiation electromagnetic noise wave shielding property: A computer and a CRT are installed in an anechoic chamber (temperature: 25 ° C., relative humidity: 70% RH), and MS is installed in a Windows 95 environment.
-Word and MS-Excel were activated to emit electromagnetic waves, and an operator having a receiving antenna (Sony / Tektronix electric field probe) attached to the chest at a position about 50 cm in front of the computer was seated. An apron made from the target fabric is worn, and the spectrum change of the radiated electromagnetic wave before / after wearing the apron is read from the analyzer to evaluate the shielding performance. The height of the peak protruding above the spectrum line indicates the intensity of the electromagnetic wave. The presence or absence of the shielding property is determined from the change in the height of the peak.

Example 1 A knitted fabric having a flat knitting structure was knitted with a single circular knitting machine having a gauge of 28 using a nylon 66 fiber multifilament yarn (60 denier / 24 filaments). After washing with hot water at 5 ° C. for 5 minutes to remove the thread-forming oil and the like and drying, the knitted fabric is deknitted to obtain a stitched crimped yarn. The stitched crimped yarn is wound into a skein shape and the skein is acetic acid (concentration: 98%): 125 cc and nitric acid:
Solution with 6.25 g (in terms of active ingredient) and water:
Glucose in 2500 cc is mixed with an aqueous solution in which 250 g is dissolved, and further immersed in a solution prepared by adding 125 cc of ethyl alcohol in an atmosphere at room temperature for 30 minutes. During this time, the skein is rotated at a constant speed of 0.5 m / sec in a fixed direction. Thereafter, the treating agent is drained and dried, and then the yarn is wound from the skein to a paper tube.

Next, silver nitrate: (in terms of active ingredient) 1
40 g was dissolved in 1200 cc of water, and 120 g of aqueous ammonia (concentration: 28%) was added thereto. Then, 100 g of caustic potassium: (in terms of the amount of active ingredient) was added to 1200: water.
aqueous solution and ammonia water (concentration 28%) dissolved in cc:
Then, a silver film forming treatment bath obtained by adding and mixing with 120 g was prepared.

The yarn wound on the above-mentioned paper tube is hung on a roller installed in the silver film forming bath, and is run at a constant speed so that the residence time in the bath is 5 minutes, and dipping is performed. And 2 more in the silver film forming bath prepared in the same manner.
After passing twice, wash with water and dry. A dense silver film having good adhesion (peelability) was formed on the surface of the yarn that passed through a total of three baths for the silver film forming treatment, and surface metalized fibers were obtained.

0.6 mm using the surface metallized fiber,
And it was arrange | positioned at grid form so that it might be set to 1.2 mm, and it interwoven with the plain fabric which used the polyester multifilament yarn (50 denier / 24 filament) in the ground | texture part, and obtained the electromagnetic wave shielding cloth. The electromagnetic wave shielding performance of the fabric was evaluated (Examples 1a and 1b). Table 1 shows the evaluation results.

[0026]

[Table 1]

Further, FIG. 2 shows the spectrum obtained by measuring the radiated electromagnetic noise wave radiated at that time by operating the computer in a dark room while wearing the apron prepared using the fabric of Example 1a. Show. FIG. 2 is a diagram showing a spectrum obtained by measuring a radiated electromagnetic noise wave after wearing an apron prepared using the woven fabric of Example 1a. In the spectrum shown in FIG. 2, there is almost no peak projecting upward from the baseline, and a shielding effect can be seen. FIG. 1 is a diagram showing a spectrum obtained by measuring an electromagnetic noise wave radiated under the same conditions without wearing an apron at all. Comparing FIG. 1 with FIG. 2, the shielding effect of the apron according to the embodiment is clear.

Comparative Example 1 Acetic acid (concentration 98%): 125
except that the step of immersing in a solution containing 6.25 g of nitric acid (converted to the active ingredient) in cc and the step of immersing in a solution of 250 g of glucose dissolved in 2500 cc of water: The mixed woven fabric prepared in the same manner as in Example 1 was evaluated in the same manner as in Example 1 (Comparative Examples 1a, 1
b). The evaluation results are also shown in Table 1.

FIG. 3 shows a spectrum obtained by measuring radiated electromagnetic noise waves while wearing an apron prepared in the same manner as in Example 1a using the woven fabric of Comparative Example 1a. 3, the electromagnetic wave shielding property is inferior to that of FIG.
In particular, a high peak is seen in a low frequency region.

Comparative Example 2 Glucose: 25 as a reducing agent
Aqueous formalin solution instead of using 0 g: 10% concentration
Is obtained in the same manner as in Example 1 except that the same plain woven fabric as in Example 1 is obtained by using the surface metallized fibers and arranging them in a grid so as to have an interval of 0.8 mm using the same. The woven fabric was evaluated in the same manner as in Example 1. The evaluation results are also shown in Table 1.

[Brief description of the drawings]

FIG. 1 is a diagram showing a spectrum obtained by measuring radiated electromagnetic noise without wearing an apron at all.

FIG. 2 is a diagram showing a spectrum obtained by measuring radiated electromagnetic noise after wearing an apron prepared using the woven fabric of Example 1a.

FIG. 3 is a view showing a spectrum obtained by measuring radiated electromagnetic noise after wearing an apron prepared using the woven fabric of Comparative Example 1a.

Claims (1)

[Claims] 1. A method of treating a polyamide fiber with an acid containing glucose, etching the fiber surface and attaching glucose to the fiber surface at the same time, and then bringing the fiber into contact with an aqueous ammonia solution containing silver nitrate to form a silver film on the fiber surface. A method for producing a surface metallized fiber.