Thermoset foams, and method for manufacturing same from reducing sugars and amines
A process for manufacturing a solid thermoset foam includes the following successive stages: (a) providing an expandable and thermosetting composition including a first reactant chosen from reducing sugars and a second reactant chosen from primary amines, primary amine acid addition salts, secondary amines, secondary amine acid addition salts, and ammonium salts of formula R n− (NH 4 + ) n where n is an integer at least equal to 1 and R n− represents the residue of an organic or inorganic acid; (b) introducing the expandable and thermosetting composition into a mold or applying the expandable composition to a support so as to form a film having a thickness at least equal to 1 mm; and (c) heating the expandable and thermosetting composition to a temperature at least equal to 140° C. to react the first reactant with the second reactant and to form, by polymerization and chemical foaming, a block of solid thermoset foam.
1. A process for manufacturing a solid thermoset foam, comprising the following successive stages:
(a) making available an expandable and thermosetting composition containing:
a first reactant chosen from reducing sugars,
a second reactant chosen from primary amines, primary amine acid addition salts, secondary amines, secondary amine acid addition salts, and ammonium salts of formula R n− (NH 4 + ) n where n is an integer at least equal to 1 and R n− represents a residue of an organic or inorganic acid,
the expandable and thermosetting composition containing less than 50% by weight of water,
(b) introducing the expandable and thermosetting composition into a mold or applying the expandable and thermosetting composition on a support so as to form a film having a thickness at least equal to 1 mm,
(c) heating the expandable and thermosetting composition to a temperature at least equal to 140° C., so as to react the first reactant with the second reactant and to form, by polymerization and chemical foaming, a block of solid thermoset foam.
2. The process as claimed in claim 1 , wherein an amount of the expandable and thermosetting composition is such that the volume of the resulting block of solid thermoset foam is at least equal to 500 cm 3 .
3. The process as claimed in claim 1 , wherein the thickness of the film is at least equal to 2 mm.
4. The process as claimed in claim 1 , wherein the block of solid thermoset foam is a slab.
5. The process as claimed in claim 1 , wherein the expandable and thermosetting composition contains at most 35% by weight of water.
6. The process as claimed in claim 1 , wherein the first and second reactants represent, in total, at least 70% of the dry weight of the expandable and thermosetting composition.
7. The process as claimed in claim 1 , wherein the first reactant is chosen from glucose and starch hydrolysates.
8. The process as claimed in claim 1 , wherein the expandable and thermosetting composition additionally contains one or more surface-active agents.
9. The process as claimed in claim 1 , wherein the expandable and thermosetting composition additionally contains up to 20% by weight, with respect to a total dry weight of the expandable and thermosetting composition, of one or more inorganic or organic fillers.
10. The process as claimed in claim 1 , wherein the first reactant represents from 30 to 95% by weight and that the second reactant represents from 5 to 70% by weight of the total weight of the first and second reactants.
11. The process as claimed in claim 1 , wherein an amount of the expandable and thermosetting composition is such that the volume of the resulting block of solid thermoset foam is at least equal to 0.01 m 3 .
12. The process as claimed in claim 1 , wherein the thickness of the film is at least equal to 10 mm.
13. The process as claimed in claim 1 , wherein the expandable and thermosetting composition contains at most 5% by weight of water.
14. The process as claimed in claim 1 , wherein the first and second reactants represent, in total, at least 90% of the dry weight of the expandable and thermosetting composition.
15. The process as claimed in claim 7 , wherein the starch hydrolysates have a dextrose equivalent (DE) of greater than 20.