JPH04136268A - Production of metallized nonwoven fabric - Google Patents

Abstract

PURPOSE:To obtain a uniformly metallized nonwoven fabric having excellent electrical conductivity by pretreating a nonwoven fabric with an aqueous solution of gelatin, uniformly adsorbing palladium hydrogel containing a cationic surfactant on the surface of the fibers and chemically plating. CONSTITUTION:The surface of a nonwoven fabric is pretreated with an aqueous solution of gelatin, then immersed in palladium hydrogel containing a cationic surfactant, palladium colloid is uniformly adsorbed on the surface of nonwoven fabric, the nonwoven fabric is washed with water to remove excessive colloid, immersed in a chemical plating solution containing a metallic ion and a reducing agent, a metal is precipitated on the surface of the fibers to uniformly and chemically plate the nonwoven fabric.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a metal-plated nonwoven fabric. Specifically, the fiber surface of the nonwoven fabric is treated in advance with an aqueous solution of gelatin, and then the treatment is carried out. The purpose of this invention is to uniformly adsorb palladium colloid on the fiber surface of the nonwoven fabric, followed by chemical plating, to obtain a nonwoven fabric with excellent conductivity and whose fiber surface is uniformly metal-plated.

Its main uses are electromagnetic wave shielding, non-woven fabric for heating elements,
This is a field where antistatic properties are required for the use of conventional nonwoven fabrics.

[Conventional technology]

Fancy cloth is often an insulator, but it is lighter and cheaper than metal materials.

Nonwoven fabrics are subjected to various processes and various metals are added thereto to give them electrical properties such as conductivity and magnetic properties.

When applying metal to a nonwoven fabric, it is necessary that the metal be applied as uniformly as possible to all layers of the nonwoven fabric, and it is required that the metal is not easily removed by contact with solid objects.

Conventionally, as a plating method for applying metal to a nonwoven fabric, there is, for example, a method described in Japanese Patent Application Laid-Open No. 61-207667. This involves applying a palladium colloid to a nonwoven fabric in a palladium hydrosil containing one or more of cationic, anionic and nonionic surfactants, and then
This is a chemical plating method.

Conventional plating methods attempt to obtain uniform adsorption of palladium colloid on the fiber surface of nonwoven fabric.

It is necessary to treat the nonwoven fabric with a strong alkali, strong acid, etc. to etch the fiber surface of the nonwoven fabric. Different processing agents are required depending on the type of fiber, making the plating method complicated. Furthermore, when carrying out this treatment, it is difficult to control the treatment, and if suitable treatment conditions are exceeded, the fibers may be severely degraded, and the person performing the plating is required to be highly skilled.

[Problem to be solved by the invention]

Although there is currently a demand for nonwoven fabrics to which metal is very easily and uniformly applied, the nonwoven fabrics obtained by the above-mentioned known methods still do not satisfy the above-mentioned characteristics.

That is, in the above-mentioned known method, in order to uniformly adsorb palladium colloid on the fiber surface of the nonwoven fabric, each fiber must be treated in accordance with the material constituting the nonwoven fabric. Nonwoven fabrics composed of two or more types of fibers have the drawback that the processing is complicated and the work is hazy, making it difficult to uniformly apply metal very easily.

As mentioned above, not only one type, but also two or more types! II
There is a strong desire to establish a method for uniformly applying metal to all layers of a nonwoven fabric made of #I.

(Means for Solving lIl) As a result of various studies on methods for uniformly applying metal to all layers of nonwoven fabric, the present inventors found that, depending on the material of the nonwoven fabric, gelatin aqueous solution can be used without changing the treatment agent. We have invented a method for uniformly applying metal to nonwoven fabrics through treatment.

That is, 9 the present invention involves treating the fiber surface of a nonwoven fabric in advance with an aqueous solution of gelatin, and then immersing the treated nonwoven fabric in palladium hydrosil containing a cationic surfactant to adsorb palladium colloid onto the fiber surface of the nonwoven fabric. This is a method for producing a metal-plated nonwoven fabric, which comprises: step 1, and then chemically plating the nonwoven fabric to which the palladium colloid has been adsorbed.

[Effect]

In the method of the present invention, the surface of the fibers of the nonwoven fabric is treated in advance with an aqueous solution of gelatin, and palladium colloid can be uniformly adsorbed onto the fiber surface, so that the surface of the fibers of the nonwoven fabric can be uniformly chemically plated. With this treatment method, regardless of the material of the nonwoven fabric, only an aqueous solution of gelatin is required as a treatment agent, so the work is simple and the treatment solution can be easily controlled. This is presumed to be due to unique properties not found in other proteins, such as gelatin's adhesive strength, and proteins other than gelatin have no effect.

Next, various conditions for implementing the present invention will be described.

In the method of the present invention, the fiber surface of the nonwoven fabric must first be treated with an aqueous gelatin solution before the palladium colloid is adsorbed onto the fiber surface of the nonwoven fabric.This treatment involves soaking the nonwoven fabric in an aqueous gelatin solution for a certain period of time. It is done by doing.

Gelatin is adsorbed on the fiber surface of the nonwoven fabric. The processing temperature in step 2 is in the range of 0 to 100°C, and since there is little difference in the effect depending on the temperature, a range of 20 to 50°C is preferable from the workability. It hardens. The treatment time is preferably 1 minute or more, preferably about 5 minutes.Even if the treatment time is 5 minutes or more, there is little difference in effect from that of 5 minutes treatment.Also, the concentration of gelatin in the aqueous solution is % by weight.
The preferable range is 0.2 to 10%. If the amount is 0.2%, the resulting plating will not be uniform. Even if it exceeds 10%, the effect is the same as that of 10% or less, so it is not economical, and it is not practical because it tends to solidify at low temperatures. In addition, if extra gelatin adheres to the nonwoven fabric due to processing, the excess gelatin with palladium colloid adsorbed will dissolve into the chemical plating solution and chemical plating reactions will occur in the solution, so this can be prevented. Therefore, it is preferable to remove excess gelatin by treating the nonwoven fabric with gelatin water ilP& and then washing with water or washing with water and drying.

Next, the nonwoven fabric treated with gelatin is immersed in palladium hydrosol for a certain period of time to adsorb palladium colloid. Palladium concentration in palladium hydrosil is 0.1
A range of ~5 wg-atom/Q is preferable.

Since the adsorption rate of palladium colloid in the present invention varies depending on the temperature of palladium hydrosil, 4°C, type of surfactant, etc., appropriate conditions may be set depending on the purpose.

The temperature may be freely selected in the range of 0°C to 100°C depending on the purpose, and the higher the temperature, the faster the palladium colloid adsorption rate tends to be.

After adsorbing palladium colloid on the nonwoven fabric.

Of course, chemical plating can be performed as is, but if excess palladium colloid is attached, the excess palladium colloid will separate into the chemical plating solution during subsequent chemical plating, and the chemical plating reaction will occur in the solution. To prevent this, it is preferable to adsorb palladium colloid on the nonwoven fabric and then remove excess palladium colloid by washing with water or washing with water and drying in the same manner as after the gelatin treatment.

Next, the nonwoven fabric with palladium colloid adsorbed is immersed in a chemical plating solution for a certain period of time to perform chemical plating.By immersing the nonwoven fabric with palladium colloid adsorbed in a chemical plating solution containing metal ions and a reducing agent, Metal ions are reduced in the palladium colloid part adsorbed on the nonwoven fabric, and the metal is precipitated.

The chemical plating solution in the present invention includes 1, for example, electrical plating solution,
In order to impart magnetic properties, one or more of neutral or alkaline nickel, cobalt, etc. can be used.

As the reducing agent for the chemical plating solution in the present invention, sodium hypophosphite, formaldehyde, etc. can be used.

As the nonwoven fabric in the present invention, one composed of organic fibers or inorganic fibers can be used. For example, there are nonwoven fabrics made of polyester, polypropylene, aromatic polyamide, carbon, and glass fiber.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

In addition, the resistance value in the example is Loresta MCP
- Measured using a TESTER surface resistance meter (manufactured by Mitsubishi Yuka LLI).

Gelatin aqueous solution: A 2% gelatin aqueous solution was used.

Palladium hydrosil: 50 μm of palladium (II) chloride was dissolved in 2.5 ml of an aqueous solution containing 250 μmol of sodium chloride, and then diluted to 941111 with pure water. While vigorously stirring this solution, an aqueous solution 1IIQ containing loImg of stearyltrimethylammonium chloride was added, and then,
When 5Q of an aqueous solution containing 200μ of sodium borohydride + sol was poured into the flask, the color of the IL solution suddenly changed, and a transparent black-brown palladium hydrosil was obtained.

<Preparation of chemical plating solution> Nickel plating solution: 4 sol of anhydrous nickel (II) chloride O, li + ol
/n in aqueous ammonia solution, and add 0.2m to the solution.
After adding 5oon Q of sodium hypophosphite in ol/Ω, the pH of the solution was adjusted to 8.9 with concentrated hydrochloric acid.

Cobalt plating solution: Dissolve 0.05■ol cobalt sulfate, 0.20■ol sodium hypophosphite, 0.20■ol trisodium citrate, and 0.20■ol ammonium sulfate in pure water. Make the total volume 1Q, add 28% ammonia aqueous solution to the solution and adjust the pH! I gave 114m to O.

Nickel-iron alloy plating solution: 0.10 01 nickel sulfate, 0.10 ol sulfuric acid to iron.

0.10-01 sodium hypophosphite, 0.20■
ol trisodium citrate and 0.20 ol ammonium sulfate were dissolved in pure water to make a total volume IQ, and 5% Na0)I was added to the solution to adjust the pH to 10.2.
Shita.

Example 1 1m of polyester! 11 non-woven fabric (MTT501 made by Nippon Feltoe 1!■ Thickness 0.1sis,
5cm x 5cm) in gelatin aqueous solution 50-Q.
After immersing at ℃ for 5 minutes, the cloth was taken out and washed with water for 3 minutes.

Next, the obtained nonwoven fabric was coated with palladium hydrosil 50+
After being immersed in +Q for 20 minutes at room temperature, the nonwoven fabric was pulled up and washed with water for 3 minutes.

The obtained nonwoven fabric to which the palladium colloid was adsorbed had a light brownish color.

Next, the nonwoven fabric on which the palladium colloid was adsorbed was immersed in a nickel chemical plating solution at 50°C for 8 minutes,
Washed with water and dried.

The obtained nonwoven fabric had a blackish metallic luster caused by nickel plating uniformly throughout the entire layer of the nonwoven fabric.

The resistance value of the second nonwoven fabric was 1.1Ω/mouth. The amount of nickel plated was 30.0% based on the weight of the nonwoven fabric.

Example 2 Nonwoven fabric composed of aromatic polyamide fiber (Nippon Felt Industry ml MXX400. Thickness 0.06-m, 5c
s x 5 cm) in the same manner as in Example 1 to obtain a nonwoven fabric to which palladium colloid was adsorbed.

The obtained nonwoven fabric to which palladium colloid was adsorbed had a light brownish tinge.

Example 1 The nonwoven fabric to which the palladium colloid was adsorbed was
Nickel plating was performed in the same manner as above.

The obtained nonwoven fabric had a blackish metallic luster caused by nickel plating uniformly throughout the entire layer of the nonwoven fabric.

The resistance value of this nonwoven fabric was 0.7Ω/mouth. The amount of nickel plated was 43.2% based on the weight of the nonwoven fabric.

Implementation fs3 Non-woven fabric made of carbon fiber (Nippon Felt Industry m
! I! E 8921 pieces, thickness 3.0+sm, 5cII
x 5cm).

A nonwoven fabric to which palladium colloid was adsorbed was obtained in the same manner as in Example fs1.

Next, the nonwoven fabric on which the palladium colloid was adsorbed was immersed in a nickel chemical plating solution at 70° C. for 40 minutes, then washed with water and dried.

The obtained nonwoven fabric uniformly exhibited a yellowish metallic luster due to nickel plating throughout the entire layer of the nonwoven fabric.

The resistance value of this nonwoven fabric was 1.3Ω/mouth. The amount of nickel plating was 21.0% for nonwoven fabric type 1.

Example 4 Nonwoven fabric composed of polyester fiber (Nippon Felt Industry a'lp NTT501, thickness 0.1+sw, 5c
m x 5cm) in gelatin aqueous solution 50+i Q
After immersing at ℃ for 5 minutes, the nonwoven fabric was pulled up and washed with water for 3 minutes.

Then, the obtained nonwoven fabric was coated with palladium hydrosil 5ow
After immersing in Q for 8 minutes at room temperature, the nonwoven fabric was bowed 3
Washed with water for a minute.

The obtained nonwoven fabric to which the palladium colloid was adsorbed had a light brownish color.

Next, the nonwoven fabric on which the palladium colloid was adsorbed was immersed in a cobalt chemical plating solution at 90°C for 3 minutes,
Washed with water and dried.

The obtained nonwoven fabric uniformly exhibited a silvery-white metallic luster throughout the entire layer due to cobalt plating.

The resistance value of this nonwoven fabric was 66.0Ω/mouth. The amount of cobalt plating was 14.7% based on the weight of the nonwoven fabric. Example 5 Nonwoven fabric composed of polyester fiber (Nippon Felt Industry ■11 MTT501, thickness O, 1 m 11.5 cm
After immersing the nonwoven fabric in gelatin aqueous solution 50IIQ at 40° C. for 5 minutes, the nonwoven fabric was pulled up and washed with water for 3 minutes.

Next, the obtained nonwoven fabric was coated with 50 m of palladium hydrosil.
After soaking in Q for 8 minutes at room temperature, lift up the immortal cloth 3
Washed with water for a minute.

The obtained nonwoven fabric to which the palladium colloid was adsorbed had a light brownish color.

Next, the nonwoven fabric on which the palladium colloid was adsorbed was immersed in a nickel-iron chemical plating solution at 80° C. for 3 minutes, washed with water, and dried.

The obtained nonwoven fabric uniformly exhibited a blackish metallic luster due to nickel and iron plating throughout the entire layer of the nonwoven fabric.

The resistance value of this nonwoven fabric was 3.4Ω/mouth. The amount of nickel and iron plated was 15.7% based on the weight of the nonwoven fabric.

Comparative Example 1 For comparison with Example 1, a nonwoven fabric made of polyester fiber (formerly Nippon Felt Industry Co., Ltd. M MTTS, thickness 0) was used.
．． 11111.5c+wX5c+*) was immersed in Palladium Hydrosil 50-Q for 20 minutes at room temperature without gelatin pretreatment, and then the non-conductive cloth was pulled up and washed with water for 3 minutes.

Next, the above nonwoven fabric was heated in a nickel chemical plating solution at 50°C.
After being immersed in water for 8 minutes, it was washed with water and dried.

In the obtained nonwoven fabric, all layers of the nonwoven fabric were not nickel plated, and the white color of the polyester fibers appeared in some areas in a patchy state.

This nonwoven fabric had some insulating properties, and the resistance value varied even in the electrically conductive parts.

The most conductive part was 7.0Ω/mouth. The amount of nickel plated was 13.7% based on the weight of the nonwoven fabric. However, since the palladium colloid can be easily and uniformly adsorbed onto the fiber surface, uniform chemical plating can be performed. By the second method, regardless of the material of the nonwoven fabric, only an aqueous solution of gelatin is required as a processing agent, so the operation is simple and the processing solution can be easily controlled. Therefore, a uniformly metal-plated nonwoven fabric with excellent conductivity can be easily obtained, so it is 1!
For magnetic wave steering and heating elements.

As a nonwoven fabric for υ11 layers suitable.

Claims (1)

[Claims] (1) After a nonwoven fabric is previously treated with an aqueous solution of gelatin, it is immersed in palladium hydrosol containing a cationic surfactant to adsorb palladium colloid on the fiber surface of the nonwoven fabric, and then the nonwoven fabric is chemically plated. A method for producing a metal-plated nonwoven fabric characterized by: