Stock material or miscellaneous articles – Composite – Of metal
Reexamination Certificate
1999-08-30
2001-07-17
Thibodeau, Paul (Department: 1773)
Stock material or miscellaneous articles
Composite
Of metal
C428S409000, C205S168000
Reexamination Certificate
active
06261697
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a plated molded article containing a styrenic polymer having a syndiotactic configuration as the major component thereof and a process for producing the article. More particularly, the present invention relates to a plated molded article advantageously used for electric and electronic parts, such as printed boards, MID (molded interconnected devices), and electromagnetic wave shields, and high precision parts used in home electric appliances, and a process for producing the article.
BACKGROUND ART
Styrenic polymers having a syndiotactic configuration (occasionally referred to as SPS hereinafter) have excellent heat stability, electric properties, and dimensional stability against moisture absorption and used for various types of high precision parts as engineering plastics. Furthermore, it has been desired that metal plated articles of SPS are developed and widely used in new fields in which plated articles of conventional acrylonitrile-butadiene-styrene copolymers (ABS) cannot be used.
Generally for plating plastic molded articles, roughness is formed on the surface of the articles by using an oxidizing agent such as chromic acid (etching), and a metal is tightly attached to the resultant surface by taking advantage of the rough structure (an anchor). In ABS which is widely used as a plastic material with plating, the butadiene part is dissolved in oxidizing agents to form the anchor because butadiene (B) is easily soluble in oxidizing agents. Therefore, the plating of ABS is easily performed.
In contrast, plating of SPS has been difficult because SPS is excellent in chemical resistance and does not have any part corresponding to that of butadiene (B) in ABS.
Generally when ABS is plated, the surface of an article is treated for formation of roughness, and after a catalyst for chemical plating is provided to the resultant surface by a combination of catalyzing and acceleration or a combination of sensitizing and activation, the surface is chemically plated, and the chemically plated surface is then electrically plated.
However, when the process described above is applied to a molded article containing SPS, problems arise in that skipped plating frequently takes place in the chemical plating, and in that a plating film having a sufficient adhesive strength cannot be obtained. Because of these reasons, no molded article having a plating film of metallic appearance has heretofore been obtained from a molded article containing SPS.
On the other hand, the plating property of plastics which do not contain any part easily soluble in an oxidizing agent, such as engineering plastics such as polycarbonates (PC) and modified polyphenylene ethers (Noryl) and general-purpose plastics such as polypropylene (PP), can be improved by blending a substance easily soluble in an oxidizing agent (Japanese Patent Application Laid-Open No. Showa 53(1978)-88876, Japanese Patent Application Laid-Open No. Showa 53(1978)-140348, Japanese Patent Application Laid-Open No. Showa 63(1988)-215760, and Japanese Patent Application Laid-Open No. Heisei 2(1990)59178).
However, the basic physical properties of SPS, such as melting point, glass transition temperature, and rate of crystallization, the surface condition of molded articles containing SPS, and the conditions suitable for obtaining molded articles containing SPS are entirely different from those of other engineering plastics, such as PC and Noryl and general-purpose plastics, such as PP or those of molded articles containing such plastics. Therefore, it has been difficult to obtain a plated molded article having a sufficient adhesive strength of the plated film by simple application of conventional technologies.
Under the above circumstances, the present inventors undertook extensive studies to solve the above problems and to obtain a plated molded article containing SPS which has a high adhesive strength of the plating film and can be produced with stability in an industrial process.
DISCLOSURE OF THE INVENTION
As the result of the above studies, the present inventors discovered that a good anchor cannot be obtained even under severe conditions when SPS alone is used as the material, and accordingly the problems cannot be solved. The present inventors studied further and enabled exhibiting a good adhesive strength of a plating film for the first time by blending a substance soluble in an oxidizing agent with SPS.
The present inventors also discovered that the easiness of etching SPS (the easiness of dissolving SPS into an oxidizing agent) is different in crystalline parts and in amorphous parts of SPS, and the crystalline parts are dissolved into an oxidizing agent with more difficulty than the amorphous parts. This discovery lead to another discovery that, by increasing the crystallinity, particularly by increasing the crystallinity in the parts close to the surface, the difficulty of dissolving SPS into an oxidizing agent can be more sharply contrasted with the easiness of dissolving the component soluble in an oxidizing agent, and it is possible that a still better anchor is formed.
The present inventors also discovered that the shape of the anchor has a great effect on the adhesive strength of plating film when SPS is used. This discovery lead to another discovery that, because the shape of the anchor is determined by the shape of the domain of the substance soluble in an oxidizing agent, the above problem can be solved by controlling the shape of the domain of the substance soluble in an oxidizing agent within a specific range.
The present inventors also discovered that the property for plating can be improved by mixing a specific amount of particulate elastomer having a specific particle diameter when SPS is used.
The present inventors also discovered that the property for plating can be improved by mixing a specific amount of inorganic compounds soluble in an oxidizing agent which have a specific particle diameter when SPS is used.
The present inventors also discovered that the property for plating can be improved by suppressing the content of water in the molded article to a specific value or less when SPS is used.
The present inventors also discovered that because SPS has an extremely low polarity, it is difficult that a catalyst for the chemical plating is attached to the surface in the catalyzing and acceleration or in the sensitizing and activation after the surface is treated with the etching, and this difficulty causes frequent occurrence of skipped plating and frequent exhibition of poor adhesive strength of the plating film. In relation to the above problem, the present inventors discovered that the skipped plating can be prevented and a plated molded article containing SPS with a high adhesive strength of the plating film can efficiently be obtained when a molded article formed with a specific resin composition containing SPS is treated by the processes of forming roughness on the surface (the etching treatment), providing polarity to the surface, and plating the surface, successively. The present invention has been completed on the basis of the above discoveries.
Accordingly, the present invention has:
(1) An object to provide a plated molded article which comprises a molded article formed with a resin composition comprising (A) 20 to 99% by weight of a styrenic polymer having a syndiotactic configuration and (B) 80 to 1% by weight of at least one selected from the group consisting of (a) rubbery elastomers soluble in an oxidizing agent, (b) thermoplastic resins soluble in an oxidizing agent, and (c) inorganic compounds soluble in an oxidizing agent, and has been plated;
(2) Another object to provide a plated molded article which comprises a molded article formed with a resin composition comprising (A) 20 to 99% by weight of a styrenic polymer having a syndiotactic configuration, (B) 80 to 1% by weight of at least one selected from the group consisting of (a) rubbery elastomers soluble in an oxidizing agent, (b) thermoplastic resins soluble in an oxidizing agent, and (c) inorganic com
Okada Akihiko
Otsuki Yusuke
Idemitsu Petrochemical Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tarazano D Lawrence
Thibodeau Paul
LandOfFree
Plated molded article and process for producing a plated... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Plated molded article and process for producing a plated..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Plated molded article and process for producing a plated... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2463969