Additive manufacturing compositions and methods
A thermosetting composition comprising a crosslinkable component such as a vinyl ester and/or an unsaturated polyester, and an initiator component, such as cumene hydroperoxide or BPO or blends of cumene hydroperoxide and methyl ethyl ketone peroxide. The composition is suitable to be used in additive manufacturing to form objects such as molds or prototypes.
1. An additive manufacturing composition comprising:
a thermosetting material comprising a cross-linkable component, wherein the cross-linkable component comprises a vinyl ester component or an unsaturated polyester component; and
an initiator of free-radical cross-linking;
wherein the composition is degassed before curing and/or during curing, and wherein, when the composition is deposited in a series of layers, the composition cures without deformation and has a peak exotherm temperature of 50° C. or less during curing as said series of deposited layers.
2. The composition of claim 1 , wherein, when the composition is curing, the composition exhibits a peak exotherm that is no more than 35° C. higher than a temperature at which the composition begins to cure.
3. The composition of claim 1 , wherein the composition cures with a rate of enthalpy change of 9 J/g-min or less.
4. The composition of claim 1 , wherein the cross-linkable component is a vinyl ester component.
5. The composition of claim 1 , wherein the initiator comprises a peroxide selected from cumene hydroperoxide, benzoyl peroxide, or blends of cumene hydroperoxide and methyl ethyl ketone peroxide.
6. The composition of claim 1 , wherein the composition cures with a linear shrinkage of 6.0% or less.
7. The composition of claim 1 , wherein the composition cures with a total contraction of 15.0% or less.
8. The composition of claim 1 , wherein the composition is essentially free of low profile agents and shrink control additives.
9. The composition of claim 1 , wherein the cross-linkable component is an unsaturated polyester component.
10. The composition of claim 9 , wherein the unsaturated polyester component is produced by a condensation reaction of an unsaturated di- or polycarboxylic acid or anhydride thereof, and a glycol and/or a polyhydric alcohol.
11. The composition of claim 10 , wherein the unsaturated di- or polycarboxylic acid is a polyfunctional acid thereof having not less than three carboxylic acid groups.
12. The composition of claim 11 , wherein the polyfunctional acid is selected from the group consisting of 1,2,4-benzenetricarboxylic acid, 1,3,5-benzene tricarboxylic acid, 1,2,4-cyclohexane tricarboxylic acid, 2,5,7-naphthalene tricarboxylic acid, 1,2,4-naphthalene tricarboxylic acid, 1,3,4-butane tricarboxylic acid, 1,2,5-hexane tricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-carboxymethylpropane, tetra(carboxymethyl)methane, 1,2,7,8-octane tetracarboxylic acid, citric acid, and mixtures thereof.
13. The composition of claim 10 , wherein the polyhydric alcohol is selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 1,3-hexanediol, neopentyl glycol, 2-methyl-1,3-pentanediol, 1,3-butylene glycol, 1,6-hexanediol, hydrogenated bisphenol A, cyclohexane dimethanol, 1,4-cyclohexanol, ethylene oxide adducts of bisphenols, propylene oxide adducts of bisphenols, sorbitol, 1,2,3,6-hexatetrol, 1,4-sorbitan, pentaerythritol, di pentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methyl-propanetriol, 2-methyl-1,2,4-butanetriol, trimethylol ethane, trimethylol propane, 1,3,5-trihydroxyethyl benzene, and mixtures thereof.
14. The composition of claim 4 , wherein the vinyl ester component is produced from a reaction between glycidyl methacrylate and a multi-functional phenol.
15. The composition of claim 4 , wherein the vinyl ester component is produced from a reaction between a polyepoxide and an unsaturated monocarboxylic acid.
16. The composition of claim 15 , wherein the polyepoxide is selected from epoxy novolacs, epoxidized fatty acids, epoxidized diolefins, epoxidized unsaturated acid esters, epoxidized unsaturated polyesters, and mixtures thereof.
17. The composition of claim 4 , wherein the vinyl ester component comprises a core shell rubber-modified vinyl ester resin.
18. The composition of claim 17 , wherein the core shell rubber-modified vinyl ester resin comprises butadiene as a core component and poly(methyl methacrylate) (PMMA) as a shell component.
19. The composition of claim 17 , wherein the core shell polymer comprises amine terminated butadiene nitrile rubber (ATBN) nanoparticles.
20. The composition of claim 17 , wherein the core shell polymer comprises particles having an average diameter of 50 to 350 nm.