Method of producing the plated molded articles by...

Details Method of producing the plated molded articles by... Method of producing the plated molded articles by...

2000-02-22

2001-10-09

Cameron, Erma (Department: 1762)

Coating processes

With pretreatment of the base

Preapplied reactant or reaction promoter or hardener

C427S348000, C427S443100

Reexamination Certificate

active

06299942

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for producing an electrolessly plated molded article in which electroless plating is applied to a molded article of a thermoplastic resin composition made of a thermoplastic resin having a high hardness and an inorganic filler, and a polyarylene sulfide resin composition for the electrolessly plated molded article. More specifically, it relates to a process for producing an electrolessly plated molded article which dispenses with chemical etching treatment upon polishing the surface of the hard molded article by a specific blast method, and a polyarylene sulfide resin composition which can preferably be used in this process.
2. Description of the Related Art
The plating of plastics has been applied to engineering plastics such as nylons, polyacetals, modified PPE, polycarbonates, modified PPE
ylon and ABS/polycarbonate since it was developed concerning an ABS resin. The plating process, namely, an electroless plating process comprises steps of degreasing, etching, neutralization, catalyst coating, activation and electroless plating. Of these, especially the etching is an important step for roughening a surface of a molded article and securing a plate adhesion by an anchoring effect.
However, in the etching step and the neutralization step, a mixed acid of chromic acid and sulfuric acid is used as an etching agent in an ABS resin, and chemicals of strong acid and strong alkali are used in other resins. Accordingly, the measures taken to the safe environmental equipment and the quality control in the steps have been serious problems. For example, in case of a thermoplastic resin having a high hardness and a strong chemical resistance, such as a polyarylene sulfide, the usual etching is difficult, and an etching treatment in which glass fibers as the filler are raised on the surface through blast polishing and then eluted with hydrofluoric acid has been required.
Accordingly, a simple method that replaces the ordinary chemical etching treatment has been in demand.
The invention aims to provide a process for producing an electrolessly plated molded article in which electroless plating with a great adhesion strength can be applied to a molded article of a thermoplastic resin composition made of a thermoplastic resin having a high hardness and an inorganic filler without conducting chemical etching treatment, and a polyarylene sulfide resin composition for the electrolessly plated molded article.
SUMMARY OF THE INVENTION
The present inventors have assiduously conducted investigations to solve the problems, and have consequently found that in a molded article obtained by mixing a polyarylene sulfide with an inorganic filler, molding the mixture and polishing the molded article with granulated alumina, catalyst coating smoothly proceeds without conducting etching treatment, which results in providing an electrolessly plated molded article having a strong adhesion strength. This finding has led to the completion of the invention. The summary of the invention is as follows.
(1) A process for producing an electrolessly plated molded article, which comprises molding a resin composition made of
(A) 100 parts by weight of a thermoplastic resin having the following properties (a1) and (a2)
(a1) an Izod impact strength of 35 J/m or less, and
(a2) a surface hardness of R115 or more in terms of a Rockwell surface hardness, and
(B) 100 parts by weight or more of an inorganic filler, then treating the surface of the molded article with blast to make a surface roughness Rmax 15 &mgr;m or more, and thereafter conducting catalyst coating, activation treatment and electroless plating.
(2) The process for producing the electrolessly plated molded article as recited in (1), wherein the treatment with blast is conducted by treatment with air blast using an abrasive having a sharp granular shape.
(3) A process for producing an electrolessly plated molded article, which comprises molding a resin composition made of
(A) 100 parts by weight of a thermoplastic resin having the following properties (a1) and (a2)
(a1) an Izod impact strength of 35 J/m or less, and
(a2) a surface hardness of R115 or more in terms of a Rockwell surface hardness, and
(B) 100 parts by weight or more of an inorganic filler, then treating the surface of the molded article with air blast using an abrasive having a sharp granular shape, and thereafter conducting catalyst coating, activation treatment and electroless plating.
(4) The process for producing the electrolessly plated molded article as recited in (2) or (3), wherein the abrasive having the sharp granular shape is granulated alumina.
(5) The process for producing the electrolessly plated molded article as recited in any one of (1) to (4), wherein the thermoplastic resin is a polyarylene sulfide or a syndiotactic polystyrene.
(6) The process for producing the electrolessly plated molded article as recited in any one of (1) to (5), wherein at least a part of the inorganic filler is a whisker.
(7) The process for producing the electrolessly plated molded article as recited in (6), wherein the whisker is one type or a combination of two or more types selected from a zinc oxide whisker, an aluminum borate whisker and a calcium silicate whisker.
(8) A polyarylene sulfide resin composition for an electrolessly plated molded article which composition is made of
(A′) 20 to 50% by weight of a polyarylene sulfide having a melt viscosity of 100 Pa·sec or less,
(B′) 5 to 50% by weight of a zinc oxide whisker,
(C′) 0 to 75% by weight of a ground inorganic filler, and
(D′) 0 to 50% by weight of a fiber reinforcement.
(9) The polyarylene sulfide resin composition for the electrolessly plated molded article as recited in (8), wherein the ground inorganic filler is one type or a combination of two or more types selected from aluminum nitride, magnesium oxide, alumina and graphite.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The preferred embodiments of the invention are described below.
Thermoplastic resin having a high hardness
The thermoplastic resin used in the invention has a high hardness, and its properties are as follows.
(a1) an Izod impact strength of 35 J/m or less, preferably 7 to 30 J/m, and
(a2) a surface hardness of R115 or more, preferably R120 to R128 in terms of a Rockwell surface hardness.
With respect to the Izod impact strength, a notched strength at room temperature is measured according to ASTM D 256, using an injection-molded piece having a size of 64×12.7×3.2 mm. Further, the Rockwell surface hardness is measured at room temperature (23° C., 50%±5% RH) according to ASTM D785, using an injection-molded piece having a size of 80×80×7 mm with an R scale [as an indenter, a steel ball having a diameter of 12.7±0.0025 is used, the indenter is put on a surface of a test piece under a test load of 60 kg (provided a standard load is 10 kg), and a return distortion amount of the test piece including the indenter is measured].
The thermoplastic resin used in the invention is such a hard resin. When the Izod impact strength exceeds 3.5 J/m or the surface hardness is less than R115 in terms of the Rockwell surface hardness, the uneven shape of the surface on the molded article by which to exhibit the anchoring effect is hardly provided.
Further, the resin of the invention is a thermoplastic resin, namely a resin having such qualities that it is softened by heating to become plastic and is hardened again by cooling. It is contrasted with a thermosetting resin. Specific examples thereof include linear polymers formed by an addition polymerization reaction, such as polyethylene, polystyrene and polyvinyl chloride, and polycondensates of difunctional monomers, such as polyesters and nylons. Of these, specific examples of the thermoplastic resin having the properties (a1) and (a2) include a polyarylene sulfide, a syndiotactic polystyrene, nylon 66, nylon 6, polyethylene terephthalate, polybutylene terephthalate, an acryli

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