JPS6358177B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conductive resin composition with excellent moldability that provides molded articles with excellent plating adhesion and which can be directly electroplated. In recent years, synthetic resin products, which are lightweight, economical, and have excellent moldability, are being used instead of metal products, so the surface of these products has been coated with metal to give them light resistance, durability, etc. Among these, metal plating is one of the most important processing methods. However, until now, metal plating methods have mainly been
It is applied to thermoplastic resins such as ABS resin and polypropylene, but since the heat resistance of thermoplastic resins is insufficient, thermosetting resins with good heat resistance are used in fields where heat resistance is required. There is a demand for the development of metal plated products. As a method for providing metal-plated products made of phenolic resin in response to such demands, there is an electroless plating method as disclosed in, for example, Japanese Patent Publication No. 15733/1983. This method involves degreasing, alkaline treatment, chemical etching, sensitizing, activating, and electroless plating (electroless copper plating) on a phenolic resin molded product, and then electroplating (copper-nickel-chromium three-layer).
This method performs metal coating. However, this method has the disadvantage that it requires a variety of complicated pretreatment steps before electroplating, and water washing must be performed in conjunction with these steps.In addition, the mixed solution used for etching is The problem was that playback required a considerable amount of effort. Therefore, in order to eliminate the complicated pretreatment process mentioned above,
A method has been proposed in which carbon black is added to a thermosetting resin such as phenol resin, which is a nonconductor, to make the resin conductive, and then linear electroplating is performed. However, although this method produces a plating film, the adhesion of the plating film to the thermosetting resin base is almost non-existent, and it has not been possible to obtain a product that can be put to practical use. The present inventors have conducted various studies to overcome the drawbacks of conventional metal plating methods for thermosetting resins, especially electroplating methods. We have found that by electroplating directly on the molded product after molding a phenolic resin crude product containing a compound, it is possible to form a plating film with excellent adhesion to the thermosetting resin base. The present invention was completed based on this knowledge. That is, the present invention relates to (A) carbon black 10~
40wt% (B) Sulfur 0.1-3wt% (C) General formula (In the formula, _R1 to _R4 are aliphatic hydrocarbon residues having 1 to 13 carbon atoms, and may be the same or different from each other, and x represents an integer of 1 to 4. Sulfide compounds 0.1~
Provided is a conductive resin composition characterized in that the remainder is a thermosetting resin containing 3 wt% and (D) a phenolic resin and a base material, and has an electrical resistivity of 500 Ω-cm or less at room temperature. It is something to do. As the carbon black of the component (A) in the conductive resin composition of the present invention, commercially available carbon blacks can be used, and there are no particular limitations. Examples include acetylene black made by the acetylene method, furnace black made by the furnace method, thermal black made by the natural gas thermal method, lamp black, and conductive carbon. Among them, conductive carbon is particularly preferable in terms of the balance between conductivity and fluidity, and an example thereof is Ketchen Black manufactured by Lion Akzo. Further, if necessary, carbon such as acetylene black, oil furnace black, graphite, etc. can be used in combination with the buttchain black. The carbon black content should be 10-40wt%. If the amount of carbon is greater than 40 wt%, the composition will be too hard and have poor rheological properties at injection molding temperatures. 10wt carbon
If it is less than %, the electrical resistivity becomes too high and a good plating operation cannot be performed. The component (B) sulfur used in the composition of the present invention may be in any modified form as long as it is a simple substance. Powdered products are convenient to use. The amount of sulfur used is usually 0.1-3wt%, preferably
It is in the range of 0.5-1.0wt%. If the sulfur content is less than 0.1wt%, the adhesion of plating will decrease. Furthermore, when the sulfur content exceeds 3 wt%, the adhesion similarly decreases. Next, in the composition of the present invention, the use of the thiuram sulfide compound (C) represented by the general formula () is essential for imparting adhesion to the plating. Examples of this compound (C) include tetramethylthiuram monosulfide, tetramethylthiuram monosulfide, dimethyldiethylthiuram monosulfide, tetraheptylthiuram monosulfide, tetramethylthiuram disulfide, and tetraethylthiuram monosulfide. Thiuram disulfide, dimethyldiethylthiuram disulfide, tetraheptylthiuram disulfide, tetramethylthiuram trisulfide, tetraethylthiuram trisulfide, tetramethylthiuram tetrasulfide, tetraethylthiuram tetrasulfide, etc. I can do it. These can be used alone or in combination of two or more. In addition, in combination with these compounds, 2-mercaptobenzothiazole, dibenzothiazyl sulfide, N
Compounds such as -cyclohexyl 2-benzothiazyl sulfanamide can also be used. In the present invention, the amount of the thiuram sulfide compound used is usually 0.1 to 3.0 wt%, preferably 0.5 to 3.0 wt%.
It is in the range of 1.0wt%. The phenolic resin used in the present invention may be either a novolac type or a resol type, or a combination thereof. A suitable base material is added to this phenolic resin, and organic and inorganic fillers such as wood flour and glass fiber are used alone or in combination. There is no particular limit to the amount of base material, but generally it is about 100 parts by weight of phenolic resin.
It is used in a range of 50 to 200 parts by weight. The conductive resin composition of the present invention includes the above (A), (B),
It is made by kneading each component (C) and (D) in the above ratio, but it is effective to add a small amount of zinc oxide as an optional component. It is of course possible to use conventional additives such as stabilizers against oxygen, deterioration inhibitors, fillers, lubricants, etc., depending on the requirements. The kneading may be carried out by any method commonly used in the industry, but roll kneading is particularly suitable. The kneading temperature is preferably as low as possible in order to avoid thermal decomposition of the polymer. The conductive resin composition of the present invention can be molded by applying a conventional molding method for thermosetting resins. For example, compression molding, transfer molding, or injection molding methods can be applied, and molding can be performed at a resin temperature in the range of 130 to 250°C. Although it is possible to plate the molded product obtained from the resin composition of the present invention immediately after molding, it is usually preferable to plating the molded product after leaving it to ripen for 2 to 4 days after molding. After cleaning with a weak alkaline detergent and rinsing with water, the wood is first washed with a Watts bath at low voltage. Perform plating for 3 minutes at 1volt and 3 minutes at 1.5volt. The plating film thus formed on the molded article of the composition of the present invention has extremely excellent adhesion. Subsequently, the film is plated at 4 to 5 A/dm ² for 5 to 10 minutes until the film thickness reaches 3 μm (nickel strike plating). From then on, normal electroplating conditions can be applied as is. For example, plating such as nickel strike plating (3 μm) + copper plating (10 μm) + nickel plating (10 μm) + chrome plating (0.1 μm) can be performed. Application examples of plastic plating of articles using the resin composition of the present invention include knobs, bottle caps, wheel caps, automobile lamp housings, grills, trims, nameplates, etc. Especially for knobs, multi-piece molding is possible. The conductive resin composition of the present invention has excellent moldability, and if this molded product is used, the complicated pretreatment process that is carried out in the conventional plating process is not necessary, or a simple degreasing and cleaning process is sufficient. So electroplating can be applied directly. The adhesion and durability of the plating film to the resin surface are excellent, and a good plating product can be obtained. Next, the present invention will be explained in more detail based on examples. Example As a phenolic resin, for 100 parts by weight of novolak resin (brand #2000) manufactured by Mitsui Toatsu Chemical Co., Ltd.
12 parts by weight of hexamine (curing agent), 100 parts by weight of wood flour,
Using 75.6 parts by weight of a mixture of 1 part by weight of stearic acid (mold release agent), 15 parts by weight of Ketsutien Black manufactured by Lion Akzo, and 0.7 parts by weight of sulfur.
Part by weight, tetramethylthiuram disulfide 0.7
parts by weight were added, and further 3 parts by weight of zinc oxide were added and mixed using a ribbon mixer. The mixture thus obtained was thoroughly kneaded with a heated roll, and then ground into powder (particle size: about 500 μm) using a pulverizer to obtain a molding material composition. A disc (diameter 150 mm x thickness 3
mm) was nickel-plated using a Watt bath and the plating was evaluated. This evaluation was performed by measuring the electrical resistivity (Ω-cm) of the molded product and the plating adhesion strength (Kg/cm) of the plated product using the following method. The results are shown in the table below. Electrical resistivity: Attach the electrodes of a tester to the surface of the molded product at 1 cm intervals and measure the resistance between them. Plating adhesion strength: Make a 1cm wide incision in the plating layer, attach one end to a spring gauge, and
Peel off in a 90° direction and read the indicated value at that time. Comparative Example A molding material composition was prepared in the same manner as in the example except that sulfur and tetramethylthiuram disulfide were not added at all, and a disk obtained by molding in the same manner as in the example was subjected to the same test. The results are shown in the table below. 【table】

Claims (1)

[Claims] 1 (A) Carbon black 10-40wt% (B) Sulfur 0.1-3wt% (C) General formula (In the formula, R ₁ to _{R 4} are aliphatic hydrocarbon residues having 1 to 13 carbon atoms, and may be the same or different from each other, and x represents an integer of 1 to 4.) The balance consists of a thiuram sulfide compound 0.1 to 3 wt% and (D) a thermosetting resin containing a phenol resin and a base material, and the electrical resistivity at room temperature is 500.
A conductive resin composition characterized by having a conductive resin composition of Ω-cm or less. 2 Conductive carbon 13 as carbon black
The conductive resin composition according to claim 1, characterized in that it contains 16 wt%. 3. The conductive resin composition according to claim 1, which contains 0.1 to 3 wt% of tetramethylthiuram disulfide as the thiuram sulfide compound.