JP2586466B2 - Manufacturing method of metal coated carbon material - Google Patents

Description

The present invention relates to a method for producing a metal-coated carbon material.

(Conventional technology) Carbon materials, especially carbon fiber (CF), are composited with resins and metals, and are used in various applications as composites called CFRP and CFRM. For the purpose of improvement, a metal coated on the surface has recently been required.

However, it is extremely difficult to form a uniform metal coating with excellent adhesion on each fiber. For example, as described in JP-A-48-47437, a fiber bundle is jetted with an electrolytic solution. Plating while expanding
Various attempts have been made such as performing electroplating while alternately applying tension and relaxation to the CF bundle as described in JP-A-106571.

(Problems to be Solved by the Invention) An object of the present invention is to form a uniform and excellent adhesion metal coating on a carbon material without requiring complicated operations and steps as in the means described above. It is to provide industrial means.

(Means for Solving the Problems) An object of the present invention described above is to provide an aqueous solution of a carbon material in the presence of an inorganic chloride of palladium inorganic salt (excluding hydrochloric acid), sodium borohydride, dimethylaminoborane, hydrazine This is achieved by performing a reduction treatment with any one selected from the group consisting of, and attaching a palladium colloid, followed by electroplating.

Here, the carbon material to be treated may be CF short fiber, fiber bundle (tow), thread, string, papermaking sheet, nonwoven fabric, knitted fabric, or the like, or a carbon molded product using an organic or inorganic binder, depending on the application. Is appropriately selected from

Palladium colloids to be attached to the carbon material prior to electroplating include inorganic chlorides, excluding hydrochloric acid, of inorganic salts of palladium such as palladium (II) chloride and palladium (II) in the presence of a cationic or nonionic surfactant. And a solution obtained by reduction treatment of an aqueous solution coexisting with sodium borohydride, dimethylamine borane, hydrazine and the like. Not applicable for acidic palladium colloids. In addition, acidic palladium colloid
Low pH and inherent problems such as corrosion of equipment,
Improvements were sought.

In the present invention, as described above, when preparing an aqueous solution of an inorganic palladium salt in preparation for the preparation of a palladium colloid, an aqueous solution of an inorganic palladium salt is dissolved in the presence of an inorganic chloride (excluding hydrochloric acid) such as sodium chloride and ammonium chloride. And Thus, the coexistence of conventional concentrated hydrochloric acid is unnecessary,
We decided to stop using the reducing agent heavy metal tin salt as well as mild liquidity. Stopping the tin salt solves the problem of wastewater treatment of the plating pretreatment solution.

Examples of the surfactant include quaternary ammonium salt type cationic surfactants such as lauryltrimethylammonium chloride, lauryldimethylbenzylammonium chloride, lauryldihydroxyethylbenzylammonium chloride, and stearyltrimethylammonium chloride; Zontes 603A, TC
-816, a cationic surfactant such as a polyamidoamine type cationic surfactant commercially available under trade names such as TAFRON ACH, 320A manufactured by Daiichi Kogyo Seiyaku Co., Ltd., and Saffanol AC manufactured by Sanyo Chemical Co., Ltd .; Sodium debenbenzenesulfonate,
Anionic surfactants such as sodium lauryl sulfate and sodium stearyl sulfate; nonionic surfactants such as polyoxyethylene octyl phenyl ether and polyoxyethylene nonyl phenyl ether; amphoteric interfaces such as stearyl dimethyl betaine and lauryl dihydroxy oxyethyl betaine Although an activator and the like can be mentioned, in the present invention, it is necessary to use a cationic or nonionic surfactant, and thereby the palladium colloid can be more uniformly and firmly adhered to the CF surface.

The electroplating method for the carbon material to which the palladium colloid is thus adhered can be performed according to a conventional method, and there is no limitation on the plating bath used. For example, nickel plating, Watt bath, sulfamic acid bath, etc .; copper plating, copper sulfate bath, copper cyanide bath, copper pyrophosphate bath, etc .; zinc plating, zincate bath, zinc cyanide bath, acid zinc bath, etc .; For chromium plating, a sargent bath, a fluorosilicate bath, etc .; for tin plating, an alkali tin bath, an acidic tin bath, etc .; for silver plating, a silver cyanide plating bath or the like is used. Among them, nickel, copper, and silver plating are industrially preferable.

(Effect of the Invention) The present invention has been able to provide an excellent plating method by finding a stable palladium colloid forming method that does not require strong acid, instead of acidic palladium colloid under strong acidity.

According to the method of the present invention, it is possible to produce a uniform and excellently adhered metal-coated carbon material, and the metal-coated carbon material thus obtained can be used as it is or in CF.
It can be widely used as RP and the like for electromagnetic shielding materials, heating elements, electric contacts, electrodes for alkaline storage batteries, acoustic diaphragms, and the like.

(Example) Hereinafter, an example will be described to facilitate understanding of the present invention.

(Example 1) An aqueous solution containing 20 mg of palladium (II) chloride and 30 mg of NaCl
Dissolve in 10 ml, add 80 ml of an aqueous solution containing 15 mg of lauryltrimethylammonium chloride to this solution, stir, and then add 10 ml of an aqueous solution containing 20 mg of NaBH ₄ little by little while stirring this solution, and add a black-brown transparent palladium hydrosol. It was created.

Unless the above surfactant was used in the hydrogel preparation step, the formed palladium was a transparent sol for a while, but became a black precipitate in a short time.

Kureha Chemical Industry Co., Ltd.
After immersing 20 g of CF tow (trade name: KCF100) for 30 minutes, the sample was washed with deionized water 3 and then dried to prepare a sample (1).

When the volume resistivity of the sample (1) and the comparative sample (2) without the palladium colloid treatment were measured,
It was 20 μΩ · cm and 150 μΩ · cm, and it was confirmed that the surface of the sample (1) was activated by palladium.

Samples 1 and 2 were electroplated as follows.

Plating bath composition Nickel sulfate 240 g / Nickel chloride 45 g / Boric acid 30 g / Additive / nickelite may (Nihon Kagaku Sangyo Co., Ltd.)
2 ml / Additive Nickelite Mighty S (Nippon Chemical Industry Co., Ltd.)
15 ml / bath pH 4.2 Bath temperature 55 ° C Current density 4 A / dm ² Energizing time 8 min Stirring air Stirring Observing the plating state with a scanning electron microscope, the product (1) of the present invention has a peeled part. On the other hand, while almost no adhering was observed, the comparative product (2) had poor adhesion between the CF substrate and the plating layer, and peeling of the plating layer occurred frequently.

(Example 2) A palladium hydrosol prepared in the same manner as in Example 1 except that polyoxyethylene (10) nonylphenyl ether was used instead of lauryltrimethylammonium chloride, and Toyo Carbon ( Example 1 using graphite sheet (trade name: PF-20) manufactured by KK
A sample (3) was prepared according to the above.

As in Example 1, the life of the palladium hydrosol was very short when no surfactant was present.

Sample (3) and was measured surface resistivity of the untreated comparison sample (4), each 50μΩ / cm ^2, was 80μΩ / cm ^2.

The electroplating and the plating state of the samples 3 and 4 were observed in accordance with the same prescription as in Example 1. As a result, the product (3) of the present invention was in a good plating state, while the comparative product (4) was in close contact. Poor properties and frequent peeling.

(Example 3) Electroplating was performed on samples 1 and 2 in the same manner as in Example 1 except that the plating conditions were changed as follows.

Plating bath composition 220 g of copper sulfate / 60 g of sulfuric acid / 50 mg of cupric chloride / additive ・ VBAC # 1 (EBARA Eugene Land Co., Ltd.) 5
ml / bath temperature 35 ° C Current density 3 A / dm ² The product of the present invention (5) had good plating throwing power and adhesion, but the untreated comparative product (6) had insufficient plating properties Met.

Claims (1)

(57) [Claims] An aqueous solution of a carbon material in the presence of an inorganic chloride of palladium inorganic salt (excluding hydrochloric acid) is reduced with any one of sodium hydride, dimethylaminoborane and hydrazine to form a cation. A method for producing a metal-coated carbon material, comprising depositing a palladium colloid stabilized by a nonionic or nonionic surfactant, followed by electroplating.