Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Patent
1997-06-23
1998-06-02
Mosley, Terressa
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
528193, 528194, 528271, 528272, C08G 6400
Patent
active
057601593
DESCRIPTION:
BRIEF SUMMARY
SPECIFICATION
The present invention relates to reflectors comprising unworked pieces of synthetic material on whose surface portion intended for the reflection of rays, a metal layer is applied. Prior art (cf. Duroplaste, Kunststoff-Handbuch, Vol. 10, Hanser-Verlag, 2nd Edition, 1988, Pages 318-319) provides producing unworked pieces, i.e. reflectors not treated by vapor deposition, through injection molding or transfer molding of BMC molding compounds. BMC molding compounds are plastic compounds comprising unsaturated polyester resins, dissolved in styrene, curing agents, additives and reinforcement fibers.
However, the unworked pieces obtained do not have sufficient surface quality. The surfaces have peak-to-valley heights of 0.2 to 0.5 .mu.m. They are therefore improved through additional lacquer/varnish treatment before the metal layer is applied. This treatment yields peak-to-valley heights of <0.1 .mu.m.
Since the lacquer/varnish treatment of the unworked pieces represents an undesirable process step, an attempt is made to produce unworked pieces for reflectors with improved surface quality which can be treated directly by vapor deposition.
EP-A 0 634 605 discloses the production of reflectors with high surface quality by injection molding of an epoxy resin molding compound which comprises as the preferred filler a quartz-kaolin mixture and wollastonite. Apart from the fact that due to the hard filler materials this molding compound leads to increased mold and machine wear, our investigations have shown that such molding compounds show a shrinkage of approximately 0.7 to 1% during the curing. In addition, a surface peak-to-valley height of only 0.1 .mu.m is attained.
It is therefore the task of the invention to describe a reflector in which the application of the metal coating on the unworked synthetic material piece (vapor deposition) can take place without the intermediate surface improvement in which the unworked piece during the curing experiences a markedly decreased shrinkage and a surface peak-to-valley height of less than 0.1 .mu.m is obtained.
The solution of the task is accomplished through a reflector according to claims 1 to 3, through a process for its production according to claim 4 as well as through a molding compound according to claims 6 to 8.
It was found that the fibers of the BMC molding compound are one of the primary reasons for the poor surface quality of the products produced from it. But, on the other hand, the fibers are considered by experts in the field to be necessary in order to lend sufficient strength to the formed bodies (unworked pieces) produced from unsaturated polyesters. This applies all the more since it is apparent that the fillers used must be fine-particled and for that reason have only a minor reinforcing effect for that reason.
It was surprisingly found that it is also possible to achieve strengths with fiber-free molding compounds based on unsaturated polyesters which are sufficient for the dimensional stability of reflectors. These molding compounds are free of styrene. These are pourable polyester molding compounds comprising polyester resins, curing accelerators as well as fillers and additives. It has been found that after shaping and curing such molding compounds show an extremely small degree of shrinkage of approximately 0.3 to 0.6% and a high surface quality with peak-to-valley heights <0.1, in particular .ltoreq.0.06 .mu.m if the fraction of filler materials is at least 50 percent by weight, the filler materials have a mean grain size of less than 10 .mu.m and if the molding compound comprises additionally a thermoplastic material. These molding compounds are formed in a manner known per se through injection molding or transfer molding processes and unworked pieces having mean peak-to-valley heights of less than 0.1 .mu.m, even of 0.06 .mu.m and less are obtained. The application of a metal coating on the surface which is to be reflecting, is carried out in a manner known per se such as is also used in vapor deposition within the scope of
REFERENCES:
patent: 4318962 (1982-03-01), Boucher
patent: 5143964 (1992-09-01), Behar et al.
patent: 5260368 (1993-11-01), Benkhoucha et al.
Glagla Roland
Lepore Santo
Monticelli Maurizio Manilo
Parramon Jose Poch
Schmidt Dirk
Bakelite AG
Magneti Marelli S.p.A.
Mosley Terressa
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