Build materials for additive manufacturing applications
AssigneeEastman Chemical Company
InventorsJames Thomas Goetz, Andrew Thomas Detwiler
Life of this patent
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Abstract
A build material for additive manufacturing applications is disclosed. The build material includes a build composition in powder form, The build composition includes a semi-crystalline polymer having a glass transition temperature of at least 70° C. and an onset melting temperature of at least 125° C., as measured by DSC, and that exhibits an amorphous return. A semi-crystalline polymer useful in additive manufacturing applications and a method for making the semi-crystalline polymer article are also described.
Claims20
A build material for additive manufacturing comprising a build composition in powder form, said build composition comprising a semi-crystalline polymer having a glass transition temperature (Tg) of at least 70° C., an onset melting temperature of at least 125° C., a Tm of at least 170° C., and a dHf of at least 21 J/g, all measured using differential scanning calorimeter (DSC) with a heating rate of 20° C./min, wherein the semi-crystalline polymer is a crystallized amorphous polymer that exhibits an amorphous return determined by subjecting the crystallized amorphous polymer to a DSC heat-cool-heat cycle performed at a heating and cooling rate of 20° C./min and plotting a DSC heat-cool-heat thermogram having a DSC first heat curve, a DSC cooling curve, and a DSC second heat curve, wherein the first heat curve shows a crystalline melting endotherm, the cooling curve does not show recrystallization upon cooling below the Tg, and the second heat curve is amorphous, wherein the crystalline melting endotherm is determined by a DSC curve showing a heat of fusion (dHf) of 2 J/g or more and amorphous is determined by a DSC curve showing a heat of fusion (dHf) of less than 2 J/g,
- wherein the Tg is measured via DSC according to ASTM E1356-08 (2014) and wherein the Tm is the highest temperature of an endothermic peak apex on the DSC first heat curve.
A semi-crystalline polymer useful in additive manufacturing, said polymer having a glass transition temperature of at least 70° C., an onset melting temperature of at least 125° C., a Tm or at least 170° C., and a dHf of at least 21 J/g, all measured using differential scanning calorimeter (DSC) with a heating rate of 20° C./min, wherein the semi-crystalline polymer is a crystallized amorphous polymer that exhibits an amorphous return determined by subjecting the crystallized amorphous polymer to a DSC heat-cool-heat cycle performed at a heating and cooling rate of 20° C./min and plotting a DSC heat-cool-heat thermogram having a DSC first heat curve, a DSC cooling curve, and a DSC second heat curve, wherein the first heat curve shows a crystalline melting endotherm, the cooling curve does not show recrystallization upon cooling below the Tg, and the second heat curve is amorphous, wherein the crystalline melting endotherm is determined by a DSC curve showing a heat of fusion (dHf) of 2 J/g or more and amorphous is determined by a DSC curve showing a heat of fusion (dHf) of less than 2 J/g,
- wherein the Tg is measured via DSC according to ASTM E1356-08 (2014) and wherein the Tm is the highest temperature of an endothermic peak apex on the DSC first heat curve.
A method for making an additive manufacturing polymer, said method comprising the steps of:
- (a) providing a bulk of amorphous polymer pellets;
- (b) solvent annealing said bulk of amorphous polymer pellets under conditions to provide a partially solvent annealed bulk of polymer pellets, wherein said pellets have a glass transition temperature (Tg) of at least 70° C. and a melting temperature (Tm) of at least 170° C., and have an amorphous center and a semi-crystalline shell sufficient to prevent the pellets from sticking in a thermal annealing process;
- and
- (c) thermally annealing said partially solvent annealed bulk of polymer pellets under conditions to provide a crystallized amorphous polymer in the form of a thermally annealed bulk of polymer pellets, wherein said pellets have a semi-crystalline center and a semi-crystalline shell;
- and
- wherein said thermally annealed polymer has a dHf of at least 21 J/g, measured using differential scanning calorimeter (DSC) with a heating rate of 20° C./min, and exhibits an amorphous return determined by subjecting the crystallized amorphous polymer to a DSC heat-cool-heat cycle performed at a heating and cooling rate of 20° C./min and plotting a DSC heat-cool-heat thermogram having a DSC first heat curve, a DSC cooling curve, and a DSC second heat curve, wherein the first heat curve shows a crystalline melting endotherm, the cooling curve does not show recrystallization upon cooling below the Tg, and the second heat curve is amorphous, wherein the crystalline melting endotherm is determined by a DSC curve showing a heat of fusion (dHf) of 2 J/g or more and amorphous is determined by a DSC curve showing a heat of fusion (dHf) of less than 2 J/g,
- wherein the Tg is measured via DSC according to ASTM E1356-08 (2014) and wherein the Tm is the highest temperature of an endothermic peak apex on the DSC first heat curve.
Dependencies are inferred from the claim text.