US4990587A
Expired / Lapsed
US
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Method of preparing toughened epoxy polymers
Assignee: UK Secretary of State for Defence
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Filing: 1988-06-22
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Granted: 1991-02-05
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Expires: 2008-06-22
Abstract
Abstract Toughened epoxy resins are prepared by curing a mixture of epoxy resin, a liquid carboxyl-terminated elastomer, and, as curing agent, a non-aromatic heterocyclic amine or a salt thereof. Cure is in two stages, the first stage at a temperature of at least 135° C. for less than two hours to provide a partly cured formulation comprising phase-separated rubbery particles in an epoxy resin matrix, and a second stage of completing the cure.
Inventors
- 👤 Steven J. Shaw
- 👤 David A. Tod
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 20:51
CPC Classifications
C; C08; C08G; C08G59/00; C08G59/18; C08G59/40; C08G59/50; C08G59/5093; C08G59/5046; C08G59/5053; C08G59/506; C08L; C08L63/00
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
134 words
A method of preparing a toughened epoxy polymer from an epoxy resin formulation, said formulation comprising a mixture of 100 parts by weight of an epoxy resin, from 12.5 to 25 parts by weight of a liquid carboxyl-terminated elastomer and from 0.5 to 15 parts by weight of curing agent, said curing agent being selected from non-aromatic heterocyclic amines and salts thereof having selectivity for a carboxy-epoxide reaction, characterised in that the method comprises curing the formulation in two stages, the first stage comprising curing the formulation at a temperature of at lest 135° C. for less than 2 hours to provide a partly cured formulation comprising phase-separated rubbery particles in an epoxy resin matrix, and the second stage comprising curing the formulation for a further period until the epoxy resin matrix is cured.
Claim 2
Independent Claim
134 words
A method of preparing a toughened epoxy polymer from an epoxy resin formulation, said formulation comprising a mixture of 100 parts by weight of an epoxy resin, from 12.5 to 25 parts by weight of a liquid carboxyl-terminated elastomer and from 0.5 to 15 parts by weight of curing agent, said curing agent being selected from non-aromatic heterocyclic amines and salts thereof having selectivity for a carboxy-epoxide reaction, characterised in that the method comprises curing the formulation in two stages, the first stage comprising curing the formulation at a temperature of at lest 135° C. for less than 2 hours to provide a partly cured formulation comprising phase-separated rubbery particles in an epoxy resin matrix, and the second stage comprising curing the formulation for a further period until the epoxy resin matrix is cured.
Claim 3
Dependent Claim
30 words
A method according to claim 1 characterised in that the first stage comprises curing the formulation at a temperature of 135° C. to 200° C. for 0.5 to 1.5 hours.
Claim 4
Dependent Claim
26 words
A method according to claim 1 characterised in that the epoxy resin formulations contains from 12.5 to 20 parts by weight of the liquid carboxyl-terminated elastomer.
Claim 5
Dependent Claim
25 words
A method according to claim 1 characterised in that the epoxy resin formulation contains from 2 to 10 parts by weight of the curing agent.
Claim 6
Dependent Claim
19 words
A method according to claim 1 characterised in that the liquid carboxy-terminated elastomer is a carboxyl-terminated butadiene-acrylonitrile liquid elastomer.
Claim 7
Dependent Claim
14 words
A method according to claim 1 characterised in that the curing agent comprises piperidine.
Claim 8
Dependent Claim
28 words
A method according to claim 1 characterised in that the first stage comprises curing the epoxy resin formulation at a temperature of from 140° C. to 190° C.
Claim 9
Dependent Claim
28 words
A method according to claim 7 characterised in that the first stage comprises curing the epoxy resin formulation at a temperature of from 145° C. to 180° C.
Claim 10
Dependent Claim
28 words
A method according to claim 1 characterised in that the second stage comprises curing the epoxy resin formulation at a temperature of from 80° C. to 200° C.
Claim 11
Dependent Claim
48 words
A method according to claim 9 characterised in that the second stage comprises curing the epoxy resin formulation at a temperature of at least 135° C. for a period of time such that the total cure time of the first and second stages is less than 10 hours.
Claim 12
Dependent Claim
22 words
A method according to claim 10 characterised in that the curing temperature employed in the first and second stages are the same.
Claim 13
Dependent Claim
12 words
A toughened epoxy polymer prepared by the method according to claim 1.
Claim 14
Dependent Claim
83 words
A toughened epoxy polymer, prepared from an epoxy resin formulation comprising a mixture of 100 parts by weight of an epoxy resin, from 12.5 to 25 parts by weight of a liquid carboxy-terminated elastomer and from 0.5 to 12 parts by weight of a curing agent, said curing agent being selected from non-aromatic heterocyclic amines and salts thereof having selectivity for a carboxy-epoxide reaction, which polymer has a fracture energy at 20° C. of from about 4.32 to about 13.82 kJm -2 .
Claim 15
Dependent Claim
83 words
A toughened epoxy polymer, prepared from an epoxy resin formulation comprising a mixture of 100 parts by weight of an epoxy resin, from 12.5 to 25 parts by weight of a liquid carboxy-terminated elastomer and from 0.5 to 12 parts by weight of a curing agent, said curing agent being selected from non-aromatic heterocyclic amines and salts thereof having selectivity for a carboxy-epoxide reaction, which polymer has a fracture energy at 20° C. of from about 4.32 to about 13.82 kJm -2 .
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-02-04 | 1994-08-06 | 1995-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-02-04 | 1998-08-06 | 1999-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-02-04 | 2002-08-06 | 2003-02-05 | $7700.00 | Window Closed / Lapsed |