JPS6232271B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing partially light-transparent polycarbonate moldings.

Conventionally, there are various methods for plating plastic products, but among them, there are some methods that allow light to pass through a part of a plated plastic molded product, i.e., the part that is not plated. A method of causing the presence of polypropylene is also known, and examples have been disclosed in which this method is applied to transparent or opaque fabrics such as acrylonitrile butadiene styrene resin (ABS resin) and polypropylene resin. (Special request 1977-
47469) However, all of the above resins have a heat distortion temperature of 87 to 115°C and an impact strength (unit: isot-notch) of about 9 to 13 kg cm/cm, and generally have low heat resistance and mechanical resistance. It had various drawbacks such as poor physical properties. However, these conventional methods cannot be applied to resins with excellent thermal and mechanical properties that are essential for electrical products and parts, so there is a strong demand for the development of methods that can be applied to such resins. Ta.

The present invention was made in view of such circumstances, and
First, as a resin to be applied to molded products, heat distortion temperature
135℃, impact strength (Izotsu/Notchi) 90Kg・
A polycarbonate resin is selected which has much superior properties in terms of cm/cm as compared to the above-mentioned resins. In addition to the above characteristics, this resin has good light stability and weather resistance, and has many other excellent properties such as a light transmittance of 93% or more. , and is said to be extremely suitable for the same parts.

However, because this resin is inherently highly resistant to chemicals, it is extremely difficult to apply plating to the surface, and masking agents are required to leave some unplated areas. There are many technical obstacles due to the lack of suitable materials, and it is virtually impossible to manufacture molded products with partially light-transmitting parts using this resin using the various methods disclosed so far. It was hot.

The present invention solves these problems and provides a method of manufacturing a molded article made of polycarbonate resin that partially transmits light, which was considered impossible in the past.

Many attempts were made in the process of completing the present invention, and first, various coating agents were investigated for creating partially non-plated portions of polycarbonate resin. In principle, the coating agent is preferably transparent, has excellent chemical resistance, and has good water repellency and coating properties. For this reason, first of all, in the case of resins other than polycarbonate resin, the currently used vinyl chloride, vinyl fluoride,
Targeting synthetic resins such as vinyl acetate and polypropylene, and wax-based coating agents, each of these is printed or applied on both the front and back sides of a polycarbonate molded product, such as a plate with an appropriate thickness. A sample was obtained by drying at ℃ for 1 hour, and after being immersed in an organic solvent solution or a chemical corrosive solution consisting of sulfuric acid, potassium dichromate, etc. for pretreatment, electroless nickel or copper plating was applied. However, as a result, either the above-mentioned coating liquids dissolve in the organic solvent or chemical corrosive liquid, or the coated surface of the coating agent becomes roughened and becomes hydrophilic, and the coated surface after electroless plating. The desired effect could not be obtained, as metal precipitation was observed on the surface.

Based on the above knowledge, the present invention has been made based on various studies, and it has been discovered that it is extremely advantageous to use a silicone-based polymer agent as a coating agent, and that it can achieve a remarkable effect compared to the above-mentioned coating agents. This has led to the completion of the present invention.

Silicone polymer agents are inherently oxidation resistant,
It was expected to be promising because it has excellent chemical resistance, water repellency, etc., and is transparent, but it is necessary to adjust the viscosity when printing or coating on polycarbonate, and it completely cures on the resin so that it does not fall off easily. There were many questions as to whether this was possible. However, experimental results show that even among silicone-based polymer agents, for example, silicone oil-based and silicone grease-based agents still form a coating film below 135°C, the upper limit of the heat deformation temperature of the polycarbonate to be coated. Since it does not fully cure and only begins to cure at temperatures above 150°C, it is unsuitable for applications where complete dry curing is desired as the object to be coated becomes softened and deformed. On the other hand, if the curing is insufficient, the coated surface will not be cured during the next immersion process in an organic solvent or chemical corrosive solution, resulting in dissolution and peeling, especially when the target is printing thin lines or small letters. It was inconvenient.

On the other hand, in the case of silicone varnish-based polymer compounds, extremely favorable results were obtained in similar tests. That is, when a product printed or coated in the same manner as above was dried at 80 DEG to 100 DEG C. for 1 hour, a coating film of about 10 to 100 .mu.m was obtained. This film will not be attacked by organic solvents or chemical corrosive liquids in the next step, and the coated surface will be smooth and highly water repellent.
In the subsequent electroless nickel or copper plating and electroplating processes, there is no metal precipitation, and when light is projected onto the molded product, the light passes through the coating surface well, making thin lines and small letters especially clear. It was found that the invention was clearly visible, and thus the intended purpose of the invention was fully achieved.

As described above, the silicone varnish according to the present invention can be completely cured by heating and drying even at a relatively low temperature, and has excellent chemical resistance and water repellency characteristic of silicone resins. Among commercially available products, preferred for application to the present invention are those manufactured by Shin-Etsu Chemical Co., Ltd.
KR255, KR114, etc. related to manufacturing, this one is 30
It is dried and solidified in 30 minutes at ℃.

Further, in the pretreatment of the molded article according to the present invention, diphenylformamide or the like is preferably used as the organic solvent liquid.

Next, in the electroless nickel or copper plating applied to the present invention, the surface of a non-conductive polycarbonate resin is immersed in a catalyst solution containing palladium chloride to deposit and adhere metal palladium nuclei to the surface. It was then immersed in a solution containing nickel sulfate as the main component and a reducing agent added thereto, or a solution containing copper sulfate as the main component and adding a reducing agent to a thickness of 0.5 μm.
A precipitated film of metallic nickel or metallic copper can be obtained.

In addition, in electrolytic plating, the above-mentioned electroless plated material is immersed in a solution such as copper sulfate and electrolyzed to form a film of metallic copper on the top surface of the electroless plating, and then a film of nickel sulfate, etc. is applied to this top surface. Bright nickel plating is performed by immersion in a solution and electrolyzed, and furthermore, decorative chrome plating, etc., is performed using a general method.

The present invention will be described in more detail below with reference to Examples.

Example 1 On the surface of a 2 mm thick plate-shaped transparent polycarbonate molded product, a light yellow transparent water-repellent material with a specific gravity of 0.9 to 1.0, a viscosity (P) of 1 to 3 at 25°C, and a non-volatile content of 50% or more was applied. A coating agent made by adding 1% by weight or less of antifoaming silicone oil as a surface active agent to an insulating silicone varnish (for example, Shin-Etsu Silicone KR255 or 114) is applied, and lines with widths of 0.2 mm and 0.5 mm are formed into 200 to 250 meshes. After printing using a screen and also printing the above coating agent on the back side of the molded product in a symmetrical area with the coated surface on the front side, it was heated at 80° to 100°C for 1
Drying was performed for a period of time to form a coating film. Then,
For pretreatment, the molded product was immersed in a diphenylform-based organic solvent (e.g., Evara Eugilite's Enilex PE-200) based on the Evala Eugilite Co., Ltd. Enilex-PC process, and washed with water, and then subjected to the method described above. Electroless nickel or copper plating was performed based on this, and then electroplating was performed on copper and nickel, but no metal was deposited on the surfaces that had been previously printed with the coating agent, which was the intended purpose. An excellent partially transparent polycarbonate molding was obtained.

Example 2 Letters with a width of 0.2 mm and a size of 3 to 4 mm were placed on the top surface of a push button for a cassette radio, which was a light-transmitting polycarbonate molded product colored red and having a wall thickness of 3 mm and a width of 0.2 mm.Example 1 Screen printing was performed according to the process described in Example 1, and the coating agent was also brushed on the symmetrical part of the back side in the same manner. After drying at 80° to 100°C for 1 hour, pretreatment was performed according to Example 1, and electroless nickel or copper was applied. Plating and electroplating were performed. Similar to Example 1, the results were very good.

As mentioned above, in the partially light-transmitting polycarbonate molded product according to this manufacturing method, the resin itself is conventionally widely used in this type of molded product.
It is much superior to ABS resin, polypropylene resin, etc. in terms of heat deformability, impact resistance strength, and translucency. It does not form any plating and its light transmittance is extremely good, so it has a more beautiful appearance for decorative plates, nameplates, etc. for electrical equipment, lighting equipment, automobile parts, mechanical parts, etc. Also, meter board, scale board,
It can be used in a wide range of fields because it provides much clearer display than conventional products of the same type for display boards and other items where functionality is important.

Claims (1)

[Claims] 1 Through both sides of a polycarbonate resin molded product that is colorless or colored, transparent, and has light transmittance,
A silicone varnish-based polymer compound that is transparent to light without being affected by organic solvents or chemical etchants for plating is partially printed or applied to the molded product, and then dried. Electroless nickel or copper plating is applied to the material immersed in a solvent or chemical corrosive solution, followed by electroplating, and finally, the printed or coated area of the silicone varnish-based polymer is left behind to form a light-opaque material. A method for manufacturing a polycarbonate molded article that is partially transparent to light and is characterized by being plated.