US 5,516,819 AGranted

Polymer compositions

AssigneeThe University of Manchester Institute of Science and Technology

InventorsStephen F. Bush, James M. Methven, David R. Blackburn

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Abstract

A method of producing a thickened organic polymeric composition useful for molding and capable of resisting post-molding shrinkage after being crosslinked comprising a cross-linkable base resin dissolved in an unsaturated monomer, and an additive resin selected from saturated polyesters and saturated amide waxes, the additive resin being crystalline at ambient temperatures and having a melting point (T.sub.m) below a temperature (T.sub.c) at which the base resin cross-linking reaction proceeds at a significant rate. The base resin and additive resin have only a partial degree of compatibility. When cooled from a temperature between T.sub.m and T.sub.c to temperature between T.sub.m and ambient the composition thickens, whereas, when it is heated to a temperature below T.sub.c, it reverts to a flowable composition.

Claims23

Dependent claims

A method of producing a thickened moulding composition comprising a cross-linkable base resin dissolved in an unsaturated monomer which method comprises the steps of:

(1) forming a mixture of the cross-linkable base resin and the unsaturated monomer,
(2) heating an additive resin to a temperature (Tm) above its melting point to fuse the additive resin,
(3) heating the mixture of the cross-linkable base resin and the unsaturated monomer to a temperature above the melting point (Tm) of the additive resin, to form a hot solution of the base resin in the unsaturated monomer,
(4) blending the fused additive resin with the hot solution of the base resin in the unsaturated monomer at a temperature (Tb) above the melting point (Tm) of the additive resin but below the cross-linking temperature (Tc) of the base resin to form a hot blend comprising the base resin, the unsaturated monomer and the additive resin, and
(5) cooling the hot blend from the temperature (Tb) to a temperature below the melting point (Tm) of the additive resin to thicken the moulding composition;
which said additive resin
(a) is a saturated said additive resin,
(b) is an additive resin which by itself is crystalline at ambient temperature and
(c) has a melting point (Tm) below the cross-linking temperature (Tc) of the base resin, which said additive resin is, when in the hot blend,
(d) in liquid form within the hot blend,
(e) distributed throughout the hot blend, and
(f) at a temperature above the melting point (Tm) of the additive resin, which said additive has
(g) only a partial degree of compatibility with the base resin to be such that on cooling the hot blend from the temperature (Tb) to a temperature below the melting point (Tm) of the additive resin in step (5), the said additive resin forms microcrystalline domains distributed throughout the moulding composition, and
which said additive resin
(h) thereby thickens the moulding composition at ambient temperature, but
(i) is molten at moulding temperatures to provide resistance to moulding shrinkage.

13 more elements

A method of producing a moulded article from a thickened moulding composition comprising a cross-linkable base resin dissolved in an unsaturated monomer which method comprises the steps of:

(1) forming a mixture of the cross-linkable base resin and the unsaturated monomer,
(2) heating an additive resin to a temperature (Tm) above its melting point to fuse the additive resin,
(3) heating the mixture of the cross-linkable base resin and the unsaturated monomer to a temperature above the melting point (Tm) of the additive resin, to form a hot solution of the base resin in the unsaturated monomer,
(4) blending the fused additive resin with the hot solution of the base resin in the unsaturated monomer at a temperature (Tb) above the melting point (Tm) of the additive resin but below the cross-linking temperature (Tc) of the base resin to form a hot blend comprising the base resin, the unsaturated monomer and the additive resin,
(5) cooling the hot blend from the temperature (Tb) to a temperature below the melting point (Tm) of the additive resin to thicken the composition,
(6) introducing the thickened moulding composition into a mould,
(7) heating the composition to a temperature above Tm but below Tc so as to break down the thickened composition into a composition able to flow within the mould,
(8) further heating the flowable composition to a temperature above Tc to cross-link the base resin, and
(9) allowing the composition containing the crosslinked base resin to cool;
which said additive resin
(a) is a saturated said additive resin,
(b) is an additive resin which by itself is crystalline at ambient temperature and
(c) has a melting point (Tm) below the cross-linking temperature (Tc) of the base resin,
which said additive resin is, when in the hot blend,
(d) in liquid form within the hot blend,
(e) distributed throughout the hot blend, and
(f) at a temperature above the melting point (Tm) of the additive resin,
which said additive has
(g) only a partial degree of compatibility with the base resin to be such that on cooling the hot blend from the temperature (Tb) to a temperature below the melting point (Tm) of the additive resin in step (4), the said additive resin forms microcrystalline domains distributed throughout the moulding composition, thereby thickening the said composition,
which said additive resin
(h) thereby thickens the moulding composition at ambient temperature, but
(i) is molten at moulding temperatures to provide resistance to moulding shrinkage.

19 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/295,610Filed 25 Aug 1994 · continuation in part
Priority: GB 01148/8823 Dec 1988
Granted: 14 May 1996
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

C08L 67/06
Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain ; Compositions of derivatives of such polymers:…
C08G 18/4879
Polyethers containing cyclic groups: containing aromatic groups
C08J 3/005
Processes of treating or compounding macromolecular substances: processes for mixing polymers
C08L 75/16
Polyurethanes having carbon-to-carbon unsaturated bonds: having terminal carbon-to-carbon unsaturated bonds