Claims
- 1. A foamed polymeric material comprising a polyester produced by a process which comprises:
- a. forming a mixture of a cyclic diacid anhydride, a poly-terminal epoxide and a mono-terminal epoxide, the ratio of total epoxy groups to cyclic diacid anhydride groups being from 1:1 to 2:1 and the epoxy-equivalent mole ratio of polyepoxide to monoepoxide being from 0.01 to 1.0, and adding to said mixture a catalytically effective quaternary salt in an amount that is from 0.0001 to 0.2 mole per mole of anhydride, and from 0.5 to 5% by weight of a blowing agent that decomposes or volatilizes under the reaction conditions of steps b, c and d.
- b. initiating a non-self-sustaining exothermic reaction between the epoxide and anhydride components of the mixture,
- c. raising the temperature of the mixture to a point at which the exothermic reaction becomes self-sustaining, and
- d. controlling the reaction conditions during the self-sustaining exothermic reaction such that the temperature of the reaction mixture is not substantially reduced until after the rate of evolution of heat by the reaction has begun to decrease;
- the time spent in stages b and c combined being less than 600 seconds.
- 2. A polymeric material according to claim 1 in which the time spent in stages b and c combined is less than 200 seconds and the time in stage c between initiation of the self-sustaining exothermic reaction and the attainment of the maximum temperature reached is less than 600 seconds.
- 3. A polymeric material according to claim 1 in which the cyclic diacid anhydride is maleic anhydride, phthalic anhydride or a mixture of maleic and phthalic anhydrides.
- 4. A polymeric material according to claim 1 in which the mono-terminal epoxide is selected from the group consisting of styrene oxide, .alpha.-methyl styrene oxide and halo-styrene oxides.
- 5. A polymeric material according to claim 1 in which the poly-terminal epoxide is one having the formula: ##STR7## where R is a hydrocarbyl radical comprising at least two aromatic nuclei.
- 6. A polymeric material according to claim 1 in which the poly-terminal epoxide is the reaction product of one mole bisphenol A with two moles of epichlorohydrin.
- 7. A polymeric material according to claim 1 in which the polyester is formed in the presence of from 0.01 to 0.001 mole of a tetra(C.sub.1 -C.sub.4)alkyl ammonium bromide or a tetra(C.sub.1 -C.sub.4)alkyl ammonium hydroxide per mole of anhydride.
- 8. A foamed polymeric material according to claim 1 wherein the blowing agent is azobisformamide.
- 9. A foamed polymeric material according to claim 1 wherein the blowing agent is water.
- 10. A foamed polymeric material according to claim 1 wherein the blowing agent is provided by partial decomposition of maleic anhydride.
Parent Case Info
This is a division of co-pending application Serial No. 646,215 filed Jan. 2, 1976.
US Referenced Citations (8)
Divisions (1)
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Number |
Date |
Country |
Parent |
646215 |
Jan 1976 |
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