Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reexamination Certificate
1992-09-09
2001-05-29
Clardy, S. Mark (Department: 1616)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C428S036300, C428S036400, C428S036900, C428S036910
Reexamination Certificate
active
06238757
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to laminate or composite plastics, which are finding increasing use in many fields in industry. By combining two or more plastics, it is often possible to positively affect or eliminate disadvantageous characteristics of one plastic by combining it with another plastic. Composite plastics also include combinations in which, for example, an inner layer of a certain plastic is combined with an often fiber-reinforced outer layer of unsaturated polyester or epoxy resins.
BACKGROUND OF THE INVENTION
A disadvantage of unsaturated polyester resins, hereinafter called UP, which have many industrially desirable properties, is the considerable shrinkage of these plastics upon curing, however; it may amount to up to 60 to 10% and may still be considerable even when fiber fillings, in particular glass fibers, are added. If shrinkage of the UP resins in cross-linking is to be avoided, it is necessary as a rule to use fillers, yet they are often undesirable for other reasons or can cause difficulties in industrial processing. Epoxy resins, hereinafter called EP, have the same disadvantages.
Laminate plastics for tubes, for instance, have therefore so far required a relatively complicated production process, since as a rule the inner layer is embodied as a so-called liner, which must be mounted on a mandrel and then provided with the jacket layer wound on its outside. In cross-linking of the jacket layer, which was previously typically done thermally, shrinkage occurs, however, which can in turn lead to hairline cracks in the liner. The production of such tubes therefore requires not only a great deal of experience, but is also time-consuming and expensive, and this makes itself felt in the relatively high prices for the finished products. Instead of the usual thermal cross-linking of the outer layer, cold curing of such synthetic resins is already known, but that has the disadvantage in turn that the UP resin, provided with hardeners and accelerators, allows only very brief processing times of the starting mixture. EP resins can also be processed by cold curing; however, the curing time is longer than with UP resins.
There is accordingly a need for practically shrinkage-free laminate plastics of thermal plastics for the inner and reaction resins for the outer layer that can be produced in a relatively economical process.
SUMMARY OF THE INVENTION
Surprisingly, it has now been found that composite plastics, preferably in the form of tubes, can be produced in it simple manner with an inner layer of thermal plastics and an outer layer of typically fiber-reinforced reaction resin, if the curing of the reaction resin is performed as light curing at approximately 20 to 60°.
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Plastverarbeiter, 34 Jahrgang, 1983, Nr. 1, pp. 31-36.
W. Nicolaus et al, “Neue Verarbeitungstechniken durch lichthartende Einkomponentensysteme*”, PLASTverarbeiter 34, Jahrgang 1983 Nr. 1.
Clardy S. Mark
Pillsbury Madison & Sutro LLP
Shelborne Kathryne E.
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