JPH0559550B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a nickel-plated porous nonwoven fabric electrode used as an electrode for a nickel-cadmium alkaline battery and a method for manufacturing the same. [Prior art and its problems] Conventionally, electrodes for nickel-cadmium alkaline batteries have been made by sintering a porous nickel plate and nickel powder, but the electrodes have a porosity of about 80%. However, it is impossible to increase the capacity of batteries, and a material with a large porosity is required. On the other hand, as a method for obtaining an electrode material with a large porosity, as shown in Japanese Patent Publication No. 38-17554, Japanese Patent Application Publication No. 49-112134, Japanese Patent Publication No. 61-40721, Japanese Patent Application Publication No. 61-76686, etc. Using organic fiber or organic foam as a base material,
(1) Impregnated with nickel powder, sintered, and reduced;
It is classified into (2) those that are fired and reduced after being plated with nickel, and (3) those that are used as is after being plated with nickel. Both (1) and (2) above require heat treatment in a reducing atmosphere, which makes continuous long roll-shaped electrodes impossible to operate continuously during battery assembly, making them difficult to use for special purposes. The problem is that it can only be used. Therefore, from this point of view, it has been considered to coat an organic fiber non-woven fabric made of alkali-resistant fibers with nickel using an electroless plating method as an electrode material, but the adhesion between the organic fiber and the nickel plating is poor. However, there are disadvantages such as low tensile strength and the inability to obtain satisfactory properties. [Problems to be Solved by the Invention] The present invention has been made through intensive research to solve the above-mentioned drawbacks of the conventional nickel electrode plate, namely, the small porosity and the impossibility of continuous use when the porosity is increased. As a result, we applied amine-curable epoxy resin as an interfiber binder to fiber aggregates composed of organic fibers, that is, fiber webs formed by carding, airlaying, spunbonding, melt blowing, etc. , the surface of an epoxy resin coating formed on the fiber surface by applying electroless nickel plating to a nonwoven fabric formed by adhesively coating the parts where the web constituent fibers intersect and contact each other and the surfaces between the fibers. We succeeded in obtaining an electrode material that increases the adhesion of the nickel plating that adheres to the electrode, has excellent electrode strength, achieves high porous capacity, and is capable of continuous operation. The organic fiber used in the structure of the present invention is preferably alkali-resistant, and polyolefin, polyvinyl chloride, polyacrylonitrile, polyamide, etc. are used. Webs as fiber aggregates formed using such fibers can be used in the form of random webs, cross webs, parallel webs, etc., as well as nonwoven fabrics produced by spunbond methods, melt blow methods, flat spinning methods, needle punch methods, water needle methods, etc. A nonwoven fabric formed by a fiber entangling method such as a punching method may also be used. In addition, amine-curing epoxy resins that can be applied to the above webs and nonwoven fabrics to bond and coat fibers include bisphenol A type, bisphenol F type, tetrahydroxyphenylmethane, polyalcohol type, and polyglycol type. type, resorcin type, novolak type, etc. Further, as the curing agent for the epoxy resin, aliphatic amines, cycloaliphatic amines, and aromatic amines are preferable, such as N-aminoethylpiperazine, metaxylene diamine, paramethanediamine, 4,
4'-diaminophenylmethane, etc. Next, in the present invention, the purpose of adhering and covering the organic fiber aggregate using an epoxy resin is to increase the strength of the nonwoven fabric to be formed and to improve the adhesion of the nickel-plated nonwoven fabric. Other hardening agents, if only to increase the size of
For example, acid anhydrides such as phthalic anhydride and pyromellitic anhydride may be used, but amine-based curing agents are suitable in order to improve the adhesion of nickel plating. In addition, as a method of using epoxy resin as an interfiber binder or a method of coating with epoxy resin, any method such as dipping method, foam glue method, spray method, coating method, etc. may be used, but it is possible to uniformly bond between fibers. A dipping method is preferred for bonding and uniformly coating the fiber surface. The electroless nickel plating process is performed in the following order: a. scouring with a sea surfactant, b. catalyzing with palladium, and c. plating. Catalysis with palladium in b. is carried out by (1) treatment with stannous chloride/hydrochloric acid solution, then palladium chloride/
There are methods such as catalyzing with an aqueous solution of hydrochloric acid, and (2) using the amino groups of the curing agent and catalyzing with only a palladium chloride/aqueous solution of hydrochloric acid, but method (1) has the best adhesion. As the reducing agent for electroless nickel plating, hydrazine derivatives such as hydrated hydrazine, hydrazine sulfate, and hydrazinium oxide are used in order to obtain highly pure nickel. In addition, the organic fiber nonwoven fabric used for electroless nickel plating can be easily obtained in a continuous length and can be coated with epoxy resin in a continuous process. Alternatively, the material may be wound up into a roll and plated by forcibly circulating the plating solution using a dyeing machine. The present invention will be explained in detail below with reference to Examples. [Example] Nylon (A) and polypropylene as organic fibers
(B), polyvinyl chloride (C), polyacrylonitrile (D)
are used individually, and the fiber weight is 60 each using a web forming machine such as a card and cross slapping machine.
g/m ² cross web is formed. Next, the above-mentioned cross web was introduced into a dipping tank filled with the following blended solution, and after dipping, the blended solution was adjusted to 50 parts (solid content weight ratio) with respect to 100 parts of fiber using a mangle, a dehydrator, etc. Compounded liquid A 828 type epoxy resin (epoxy resin)
EA55: Manufactured by Kanebo NSC) 100 parts (b) Polyamide curing agent (Epokey H258: manufactured by Mitsui Petrochemicals) 20 parts (c) Water However, the blending ratio of A and B indicates the solid ratio, and the ratio of A and B should be kept constant. and add water to make a concentration of 20% (solid content). Next, the webs impregnated with the blended solution were introduced into a dryer, and subjected to drying and heat treatment to form base nonwoven fabrics each having a thickness of 2.5 mm to 2.7 mm and a basis weight of 90 g/m ² as shown in Table 1.

[Table] Comparative Example 1 Cross webs A to D, each made of the same fibers and having the same basis weight as in the example, were immersed in the following formulation solution. Compounded liquid A 828 type epoxy resin (ADEKA RESIN
EP4100: Manufactured by Asahi Denka Co., Ltd.) 100 parts Acid anhydride (Adeka Hardna EH700: Manufactured by Asahi Denka Co., Ltd.) 85 parts Haxylol However, the blending ratio of A and B indicates the solid ratio. Keeping the ratio of A and B constant, add xylol and concentrate
20% (solid content). After soaking, mix the mixture with 50 parts per 100 parts of fiber.
parts (weight ratio of solid content), and introduced into a dryer to perform drying and heat treatment to form base nonwoven fabrics A to D, respectively. Comparative Example 2 Cross webs A to D, each made of the same fibers and having the same basis weight as in the example, were used and lightly needle punched to form a nonwoven fabric. Each of the base nonwoven fabrics (width 1 m x length 50 m) obtained in the above Examples and Comparative Examples 1 and 2 was wrapped around the carrier of a dyeing machine, and the scouring agent was circulated and washed with water, followed by 10 g of stannous chloride and hydrochloric acid. Circulate an aqueous solution containing 20 ml of palladium chloride and 20 ml of palladium chloride/hydrochloric acid after washing with water.
Catalysis was carried out by circulating an aqueous solution containing ml/ml. After washing with water, an electroless nickel plating solution containing 18 g of nickel sulfate, 10 g of sodium citrate, 50 ml of hydrated hydrazine, and 100 ml of 25% aqueous ammonia was heated to 80° C. and circulated. After 1 hour, circulation was stopped, and washing and drying were performed. As shown in the drawings, the nickel-plated nonwoven fabric electrode of the present invention formed in this way has a portion 2 where the organic fibers 1 such as nylon or polypropylene that form the nonwoven fabric electrode intersect and contact each other, and the surface of the fibers extending from the portion. 3 is adhered and coated with an epoxy resin 4, and nickel 5 is firmly adhered to the surface of the fiber coated with the epoxy resin 4 by electroless plating to form a continuous coating. In addition, the results of measuring the characteristic values of the nickel-plated nonwoven fabric electrodes obtained in the above Examples and Comparative Examples were
Shown in the table.

【table】

[Table] As is clear from Table 2, Examples A~ are excellent in both plating adhesion and tensile strength of the nonwoven fabric.
Regarding D, the porosity and volume resistance were measured. Although the porosity was calculated based on the heat required to impregnate the active material with 1.5 mm, the porosity is actually higher than that. The measurement results are shown in Table 3.

〔Effect of the invention〕

The nickel-plated nonwoven fabric electrode of the present invention has the above-described structure, which eliminates the need for firing treatment in a reducing gas atmosphere, saves labor in the production process, and improves porosity, conductivity, tensile strength, and plating adhesion. A novel electrode material that has both excellent properties and continuity, which has not been seen before, was obtained.

[Brief explanation of drawings]

The drawing is an enlarged sectional view of a main part of a nickel-plated nonwoven fabric electrode showing an example of the embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Organic fiber, 2... Cross contact part, 3... Fiber surface, 4... Epoxy resin, 5... Nickel coating.

Claims (1)

[Claims] 1. A nickel coating is formed by electroless plating on the surface of a base nonwoven fabric formed by integrally adhering and coating an organic fiber aggregate using an epoxy resin as a binder. Nickel-plated nonwoven fabric electrode. 2.Claim 1, wherein the curing agent for the epoxy resin is an aliphatic amine, a cycloaliphatic amine, or an aromatic amine.
Nickel-plated nonwoven fabric electrode as described. 3 After forming a nonwoven fabric by bonding and covering the fibers together with epoxy resin using a binder application method such as impregnation, coating, or spraying, the organic fiber aggregate is subjected to scouring and catalyst activation treatment, and then A method for producing a nickel-plated nonwoven fabric electrode, comprising forming a nickel film on the surface of an epoxy resin covering the fiber surface of the nonwoven fabric by an electroless plating method.