Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1986-10-10
1988-08-23
Short, Patricia
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
523500, 523514, 523516, 523527, 524 39, 524399, 524431, 524437, 524513, 524539, C08L 6706
Patent
active
047661631
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention provides polyester thermosetting resin compositions and products obtained from formulations containing such compositions, in which the polyester is chemically modified by reaction with organosilicone thermosetting compounds, in particular, organosilicone thermosetting elastomers.
More particularly, the invention provides polyester thermosetting resin "dough" moulding compositions wherein a "dough" comprising the chemically modified polyester thermosetting resin composition, catalyst, fillers and additives can be formed to shape in hot dies under high pressure, although in other embodiments the chemically modified polyester may include thermosetting resin compositions which are suitable for extruding, pultruding and hand lay-up processes and injection, compression and transfer moulding by appropriate changes therein.
In the past it has been suggested to add silicone prepolymers to certain thermoplastic materials and reference may be made to the publication "Plastics Technology", August 1985, pp 57-61. This publication describes the interpenetrating polymer networks which develop when a silicone prepolymer is admixed with a thermoplastic resin.
No prior art is known which describes the cross-linking by free radical or siloxane hydride to unsaturated bond reactions of heat-curable thermosetting organo-silicone compounds, in particular, organo-silicone thermosetting elastomer materials, into unsaturated polyester resins to form heat-curable cross-linked polyester thermosetting resins. By "thermosetting" is meant a polymeric composition capable of being cured or cross-linked so that it cannot be re-melted without destroying its chemical nature. Thermosets are characterized by the presence of extensive primary covalent bonds between molecules, in distinction to the weak secondary intermolecular forces characteristic of the re-meltable thermoplastic polymers.
SUMMARY OF THE INVENTION
In accordance with the present invention, there are provided new polyester thermosetting resins which can be used in moulding, extruding and pultruding processes, wherein an organo-silicone thermosetting compound, in particular, an organo-silicone thermosetting elastomer compound, is reacted with an unsaturated polyester resin, optionally with additives, leading to a new type of cross-linked polyester silicone polymer having many improved properties in the final product.
Thus, in contrast to the prior art, in which only interpenetrating networks were considered, which do not involve primary chemical bonds between cross-linked networks of a particular type (ie polymer A cross-links with polymer A and polymer B cross-links with polymer B, but not polymer A with polymer B; polymers A and B cross-link to form an intertwining and inextricable mixture), the present invention provides new polyester/organo-silicone thermosetting resins, in particular, organo-silicone thermosetting elastomer resin compositions in which the organo-silicone component actually cross-links by primary chemical bonds with the polyester resin, forming a solid polyester/silicone chemically cross-linked network.
Formulations comprising a polyester thermosetting resin, in particular, an organo-silicone thermosetting elastomer compound, catalyst (generally tertiary butyl perbenzoate), cellulose acetate butyrate or other appropriate low-profile or low-shrinkage additives, with fillers such as alumina trihydrate and fibre material, as well as mould release agents such as zinc stearate in appropriate proportions, can be cured together under heat and pressure to give products which are superior in quality to that formed in the absence of the silicone elastomer. Variations in the formulation lead to a variety of desirable properties and material that can be injection moulded, transfer moulded, compression moulded, extruded or pultruded.
Thus, the heat-cured thermoset polyester resin/thermoset organo-silicone compound, with or without the benefit of a low-profile or low-shrinkage additive and/or fillers, provides a complex interp
REFERENCES:
patent: 2937230 (1960-05-01), Rogers
patent: 3919438 (1975-11-01), Urkevich
patent: 4097446 (1978-06-01), Abolins
patent: 4178412 (1979-12-01), Sage
Lubin, Handbook of Composites, pp. 19-37, Van Nostrand Reinhold Co., N.Y., 1982.
Bridges Corporation Pty Ltd
Short Patricia
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