Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1981-12-28
1983-11-29
Phynes, Lucille M.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
524422, 524425, 524542, 525398, C08K 904
Patent
active
044181620
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method for the surface treatment of polyacetal resins. More particularly, the invention relates to a surface treatment method which is preferably adopted as the pre-treatment of polyacetal resins to be carried out prior to plating.
TECHNICAL BACKGROUND
Polyacetal resins have excellent thermal, mechanical and chemical properties. At the present time, however, since they are relatively expensive, they are mainly used as engineering resins for the manufacture of functional parts.
Looking to the future from the point of view of the raw materials for resins, it is expected that polyacetal resins formed by using methanol as the starting material will become one of the cheapest resins.
Therefore, it is expected that polyacetal resins will be applied even in those fields where ABS resins and the like are now applied, such as, for example, the manufacture of shaped articles decorated by plating and coating. In this field, however, the surface inactivity which is a merit of a polyacetal resin in the conventional uses becomes a defect. Therefore, the surface treatment of polyacetal resins is an important technical problem. By the term "surface treatment" is meant treatment which renders the surface hydrophilic so that plating or coating becomes possible.
It is said that polyacetal resins can be surface activated by etching with a chromic acid mixture, phosphoric acid, sulfonic acid or the like. However, although the surface is roughened by carrying out the etching according to such a conventional method, complete activation is impossible.
DISCLOSURE OF THE INVENTION
We carried out research on the relationship between changes of the surface by etching of a shaped article of a polyacetal resin and the kinds of treating agents. It was found that when a polyacetal resin is treated with a liquid mixture of hydrochloric acid and sulfuric acid good activation can be attained although use of each acid singly does not result in good activation, even with a thin depth of etching of less than several .mu.m .
A polyacetal resin shaped article etched according to the method of the present invention can be plated by the same steps as those adopted for the plating of ABS resins. The plated article obtained has a high adhesion comparable to that of a plated ABS resin article and a heat resistance superior to that of a plated ABS resin article. Furthermore, the treated article can be surface-decorated and bonded, for example by coating, vacuum deposition or sputtering.
We have also carried out research on the composition of the polyacetal resin to be treated, and have found that a polyacetal resin containing calcium carbonate is especially preferred. By the use of this polyacetal resin, the effects of the present invention can be further enhanced.
More specifically, in accordance with the present invention, there is provided a method for the surface treatment of polyacetal resins, which comprises treating a shaped article of a polyacetal resin, preferably a polyacetal resin containing calcium carbonate, with an acidic solution containing chloride ions and sulfuric acid ions.
The treatment method of the present invention will now be described in detail.
In one embodiment of the present invention, a shaped article is prepared from a polyacetal resin according to a customary procedure, and the treatment of the present invention then carried out, preferably after annealing and degreasing. The treatment is ordinarily accomplished by dipping a shaped article of a polyacetal resin for a predetermined time in an acid solution of sulfuric acid containing chloride ions. For example, in the case of a liquid mixture of 1 part by volume of concentrated hydrochloric acid, 1 part by volume of concentrated sulfuric acid and 2 parts by volume of water (about 8.6% by weight of HCl plus about 35.3% by weight of H.sub.2 SO.sub.4), the treatment is accomplished within 5 to 30 minutes at 25.degree. C. The article treated according to the invention is subjected to neutralization and washing with wat
REFERENCES:
patent: 3248271 (1966-04-01), Rielly et al.
patent: 3255060 (1966-06-01), Neumann et al.
patent: 3763084 (1973-10-01), Grudus et al.
Ikenaga Yukio
Kasuga Takuzo
Yamawaki Masami
Phynes Lucille M.
Polyplastics Co. Ltd.
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