JPS623173B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for plating polyester resin injection molded products. More specifically, it relates to a plating method in which the plating properties are improved by simply modifying the surface properties of the resin molded article without impairing the physical or chemical properties of the aromatic polyester resin. It is something. Thermoplastic polyester resins, such as polyethylene terephthalate (hereinafter simply referred to as PET resin) and polybutylene terephthalate (hereinafter simply referred to as PET resin)
PBT resin (PBT resin) has excellent mechanical properties, heat resistance, and chemical resistance, and is used as an engineering plastic in various electrical and mechanical parts. Metal-plated molded products are expected to be applied to new fields that require heat resistance and mechanical strength that cannot be used with conventional ABS resin or polypropylene resin-plated products. Generally, the methods of plastic plating include (1) pretreatment;
The process consists of (2) chemical etching, (3) sensitizing, (4) activating, (5) chemical plating, and (6) electroplating, and various methods are used depending on the type of plastic. There is. for example
For ABS resin, the purpose of the pretreatment process (1) is to remove oils and fats from the surface of the molded product, and the subsequent chemical etching process (2) roughens the surface using an oxidizing acidic solution such as chromic acid-sulfuric acid. Proceed, below (3),
Through steps (4) and (5), a finished plated product with excellent adhesion can be obtained. On the other hand, polyester resins such as polyethylene terephthalate and polybutylene terephthalate are relatively stable against acidic liquids, and even when treated with the above-mentioned chromic acid-sulfuric acid mixture, surface roughening is insufficient. Even after the subsequent plating step, sufficient adhesion strength cannot be obtained. On the other hand, when an alkaline solution is used as the etching solution, surface roughening progresses. This is thought to be because the surface of the polyester resin is hydrolyzed by the alkali and a portion of it is dissolved in the etching solution. However, although this treatment improves the adhesion to the plating metal film to some extent, it is not completely satisfactory, and there has been a desire in the industry for a method for improving the plating property. In order to improve the difficulties in the plating method for such polyester resin injection molded products, the present inventors
As a result of intensive research on improving the physical and chemical properties of polyester resin and on etching conditions, we have discovered that by mixing fillers with polyester resin, properties that are extremely suitable for plating are developed, and the surface can be easily roughened. The present invention was also achieved by discovering that injection molded articles made of the composition have good plating properties when treated with an alkaline solution. That is, the present invention provides a method for plating a thermoplastic polyester resin injection molded article, in which the injection molding is performed using a polyester resin composition in which the polyester resin contains 5 to 100 parts by weight of a filler per 100 parts by weight of the polyester resin. This is a method for plating polyester resin injection molded products, which is characterized in that the product is brought into contact with an alkaline solution and then plated. The thermoplastic polyester resin referred to in the present invention is
Terephthalic acid, naphthalene-2 and 6 as acid components
- Dibasic acids such as dicarboxylic acids and isophthalic acids or their ester derivatives are used, and as the glycol component, glycols having 2 to 6 carbon atoms, such as ethylene glycol, propylene glycol, butylene glycol, are mainly used, but other neopentyl Polyesters polymerized using glycol may also be used. Particularly preferred polyesters include aromatic polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, and polybutylene-2,6-naphthalate. It may also be a mixture or copolymer of these polyesters. Typical fillers used in the present invention include fibrous reinforcing fillers such as asbestos fibers and carbon fibers, glass beads, gypsum, mica, clay, silica, calcium silicate, talc, antimony trioxide, and Examples include granular or plate-like fillers for general plastics such as titanium. It is also possible to use two or more of these fillers in combination. The amount of these fillers added is preferably 5 to 100 parts by weight per 100 parts by weight of the polyester resin component. 5
If it is less than 1 part by weight, the adhesion between the polyester resin and the plating coating will be insufficient, and if it exceeds 100 parts by weight, manufacturing and molding will be difficult and the appearance of the finished plated product will be considerably inferior. Various methods can be considered for blending the above-mentioned filler into the polyester resin, but if the filler is not sufficiently dispersed into the polyester molded product, the surface appearance of the finished plated product obtained will be poor, so as long as possible before molding. It is desirable to knead it uniformly. The most common kneading method is to melt-knead the polyester and the filler using an extruder at a temperature higher than the melting temperature of the polyester resin. In addition to the fillers mentioned above, different types of polymers, colorants, lubricants, foaming agents, flame retardants, stabilizers, etc. may be added in amounts that do not impair the plating property improvement effect for the purpose of improving other properties of the polyester resin. good. It is possible to adopt a relatively wide range of alkali treatment conditions for surface roughening (etching) these filler-containing polyesters; Considering the characteristics of , it is desirable that the following equation holds. 15000≧C・2(T-20/10)・t≧20 [However, C, t and T in the formula are as follows. C: equivalent concentration of alkaline aqueous solution (standard) t: treatment time (minutes) T: treatment temperature (°C)] After treatment with alkaline aqueous solution under the above conditions, sensitizing and activating, which are widely used for plastics, are performed. The plating operation is completed through processes such as plating, chemical plating, and electric plating. Note that C, t, and T in the above formula are not particularly limited, but preferably, C is 0.1 to 10N, and t is 1 to 10N.
40 minutes, T is 20-80°C. When an injection molded article made of the composition of the present invention is treated with an alkaline solution, the polyester resin on the surface of the outermost layer of the injection molded article is dissolved by the alkali, but if the filler is resistant to the alkaline solution, the polyester resin It is presumed that only the components are selectively dissolved, and as a result, the filler remains in the form of convex portions on the surface of the injection molded product, resulting in surface roughening. On the other hand, if the filler is easily dissolved in the alkaline solution, it is assumed that the filler is eluted and the surface of the injection molded product is roughened in the form of recesses. It is presumed that an injection molded article made of a composition to which a filler has been added in this way has a surface condition that allows good adhesion to metal in the subsequent plating step. It is also assumed that surface roughening is affected by the filler, especially its shape and size, and if large convexes or concave areas are formed, the appearance (gloss and surface smoothness) of the molded product after plating will deteriorate. It is assumed that it will come. Therefore,
It is desirable to avoid fillers with extremely large particle sizes (eg, 100 μm or more). The present invention will be specifically explained below with reference to Examples. Of the measurement items used in this example, bending strength, impact strength, and heat distortion temperature were measured individually.
It was conducted according to ASTM D-790, D-256 and D-648. Intrinsic viscosity of polyester resin [η]
was measured at 35°C using orthochlorophenol solvent. Furthermore, "parts" are "parts by weight." Example 1 100 parts of polyethylene terephthalate with [η] = 1.02, which had been dried with hot air at 120°C for 5 hours, was mixed with 25 parts of the various fillers shown in Table 1 in a tumbler, and then mixed in a vent type 65 mmφ extruder. The mixture was melted and mixed at a cylinder temperature of 270 to 280°C, and the threads coming out of the die were cooled and cut to obtain pellets for molding. This pellet was used in a 5-ounce injection molding machine at a cylinder temperature of 280℃ and an injection pressure of 1000Kg/cm ² .
Test molded products were injection molded at a mold temperature of 140°C and a molding cycle of 45 seconds. The bending breaking strength and heat deformation temperature of the injection molded products obtained are shown in Table 1. After washing and degreasing this injection molded product with a neutral detergent, it was immersed in a 5N aqueous sodium hydroxide solution at 50°C for 20 minutes, thoroughly washed under running water, and electroplated with copper according to the conventional method shown below. was applied. (1) Sensitizing The surface roughened molded product is treated with stannous chloride 20
10 c.c. of hydrochloric acid (38% aqueous solution) and 1000 c.c. of water at 25°C for 3 to 5 minutes (2) Washing with water Immerse in running water for 1 to 2 minutes. (3) Activating palladium chloride 0.5g, hydrochloric acid (38% aqueous solution)
5 c.c. and water 1000 c.c. for 2 to 5 minutes at 25°C. (4) Rinse with running water for 1 to 2 minutes. (5) Chemical Nickel Metsuki Soak for 10 minutes at 40-50℃ in a solution with a pH of 8-9 consisting of nickel sulfate 20g/, sodium hypophosphite 15g/, ammonium sulfate 50g/, and sodium citrate 20g/ (6) Water Washing 1 to 2 minutes in running water (7) Electrolytic copper plating Copper sulfate 220g/, sulfuric acid 50g/, brightener [UBAC#1 (Ebara Eudylite Co., Ltd. product) 5g/
3A/3A at a temperature of 25-30℃ in an aqueous solution consisting of
A current was passed for 30 to 60 minutes at a current density of dm ² to form a plating film with a thickness of about 40 μm on the resin molded product. Table 1 shows the adhesion strength between the resin layer and the copper film of the molded product obtained through the above treatment steps. The adhesion strength represents the strength when a 1 cm wide adhesion surface is peeled off in a 90° direction at a peeling speed of 5 cm/min.

【table】

[Table] From Table 1, it is observed that when polyester resin contains a filler, the adhesion strength is greatly improved;
It is clear that those containing no material have low adhesion strength and are practically unusable. Example 2 Polybutylene terephthalate 100 with [η] = 1.13
Titanium oxide [Titan Kogyo Co., Ltd. brand: KA30 particle size average 0.3 μm] was added to the mixture in the amount shown in Table 2, and the mixture was melt-mixed in a twin-screw extruder to obtain injection molded pellets. . Using this pellet, test pieces for plating (thickness ² mm x width 100 mm x length
100mm) was molded. Using this test piece, it was subjected to an etching process and a plating process in the same manner as in Example 1, and the adhesion strength with metal was measured and the appearance was observed. The results obtained are shown in Table 2.

[Table] As shown in Table 2, if the amount of titanium oxide added is less than 5 parts, the etching effect will be insufficient, so the adhesion strength will not reach the practical range, and the appearance will be poor due to unevenness. . If the amount of filler added is more than 100 parts, the adhesion strength will be relatively good, but the moldability of the resin will be poor, making it difficult to obtain a homogeneous molding material, and the appearance after plating will also lack homogeneity. This is not desirable. Example 3 100 parts of polyethylene terephthalate resin with intrinsic viscosity [η] = 0.75, 30 parts of glass fiber and 10 parts of talc powder (diameter approximately 2μ) were added, and extrusion mixing and injection molding were performed in the same manner as in Example 1. A molded article for testing was obtained. After etching with various alkaline aqueous solutions using this test piece, the same operations as in Example 1 were carried out to obtain a plated finished product. Although the finished plating product contained glass fiber, its specularity was somewhat poor, but other properties were generally good, so the adhesion strength was measured and the appearance was observed. The results obtained are shown in Table 3.

【table】

[Table] From Table 3, the effect of alkaline aqueous solution treatment on the polyester resin composition is clear.

Claims (1)

[Claims] 1. In a method of plating a thermoplastic polyester resin injection molded product, asbestos fibers, carbon fibers, glass beads, calcium carbonate, gypsum, etc. in an amount ratio of 5 to 100 parts by weight per 100 parts by weight of the polyester resin are added to the polyester resin. One or two selected from mica, clay, silica, calcium silicate, talc, antimony trioxide, and titanium oxide
1. A method for plating a polyester resin injection molded product, which comprises contact-treating an injection molded product made of a polyester resin composition containing one or more fillers with an alkaline solution, and then plating including an electroplating step.