Powder compositions and methods of manufacturing articles therefrom

1. A powder composition, comprising:

a laser-sinterable powder including at least 20 weight percent of a polyamide polymer component;

wherein the polyamide polymer component includes one or more branched polyamide polymers in an amount that comprises at least 5 weight percent of the laser-sinterable powder, wherein the branched polyamide comprises a star polymer having a single branching unit and at least 3 oligomer or polymer arms covalently attached to the branching unit, wherein the single branching unit is formed from a polycarboxylic acid, wherein at least one of the oligomer or polymer arms comprises a reaction product of reactants including a C11-C20 amino acid, a C11-C20 lactam, or a mixture thereof, and wherein the powder composition has a melt enthalpy of less than 100 J/g and a sintering window of less than 40° C.

2. The powder composition of claim 1 , wherein the oligomer or polymer arms are attached to the branching unit via amide linkages.

3. The powder composition of claim 1 , wherein the polycarboxylic acid is chosen from benzene-pentacarboxylic acid; mellitic acid; 1,3,5,7-naphthalene-tetracarboxylic acid; 2,4,6-pyridine-tricarboxylic acid; pyromellitic acid; trimellitic acid; trimesic acid; 3,5,3′,5′-biphenyltetracarboxylic acid; 3,5,3′,5′-bipyridyltetracarboxylic acid; 3,5,3′,5′-benzophenonetetracarboxylic acid; 1,3,6,8-acridinetetracarboxylic acid; 1,2,4,5-benzenetetracarboxylic acid; and anhydrides, amides, or esters thereof; or a mixture thereof.

4. The powder composition of claim 1 , wherein the polycarboxylic acid comprises trimesic acid.

5. The powder composition of claim 1 , wherein at least one of the oligomer or polymer arms comprises a reaction product of reactants including a C2-C20 amino acid, a C4-C20 lactam, or a mixture thereof.

6. The powder composition of claim 1 , wherein the branched polyamide includes a nylon-11 branch unit, a nylon-12 branch unit, or a combination thereof.

7. The powder composition of claim 1 , wherein the branched polyamide includes polyamide branch units formed from laurolactam, aminoundecanoic acid, or a mixture thereof.

8. The powder composition of claim 1 , wherein the polyamide polymer component includes at least 3 carboxylic end groups per amine end group.

9. The powder composition of claim 1 , wherein the laser-sinterable powder comprises a ground powder.

10. The powder composition of claim 9 , wherein a test specimen exhibits an elongation at break of at least 3% when the powder composition is laser-sintered to form the test specimen.

11. The powder composition of claim 1 , wherein the branched polyamide is a reaction product of one or more AB compound and one or more B n compound, wherein:

A and B are functional groups capable of reacting with one another;

n denotes the number of B functional groups present in the B n compound, and wherein n is 3 or more;

B is a carboxylic group; the AB compound is a cyclic amide, an amino acid, or a combination thereof and

the stoichiometry of the mole equivalents of Bn compound to mole equivalents of AB compound ranges from 0.0001:1 to 0.03:1.

12. The powder composition of claim 1 , wherein the powder composition has a melt enthalpy of 60 J/g to 70 J/g.

13. The powder composition of claim 1 , wherein the branched polyamide includes a nylon-12 branch unit.

14. The powder composition of claim 1 , wherein a volume-average particle diameter of the powder composition is between 5 and 100 microns.

15. The powder composition of claim 1 , wherein at least one of the oligomer or polymer arms comprises a reaction product of reactants including a C11-C20 lactam.

16. A method comprising;

providing a polyamide polymer component that includes one or more branched polyamide polymers and is a reaction product of:

a first compound having at least three carboxylic groups; and

a second compound comprising a C11-C20 lactam, a C2-C20 amino acid, or a combination thereof;

forming a laser-sinterable powder that comprises at least 20 weight percent of the polyamide polymer component, wherein the one or more branched polyamide polymers of the polyamide component comprise at least 5 weight percent of the laser-sinterable powder, and wherein the laser-sinterable powder has a melt enthalpy of less than 100 J/g and a sintering window of less than 40° C.

17. The method of claim 16 , further comprising grinding the polyamide polymer component to form the laser-sinterable powder.

18. The method of claim 17 , further comprising melt blending the polyamide polymer component with one or more other materials prior to grinding.

19. A method, comprising:

providing a layer of a sinterable powder composition that comprises:

at least 20 weight percent of a polyamide polymer component,

wherein the polyamide polymer component includes one or more branched polyamide polymers in an amount that comprises at least 5 weight percent of the sinterable powder, and wherein the branched polyamide comprises a star polymer having a single branching unit and at least 3 oligomer or polymer arms covalently attached to the branching unit, wherein the single branching unit is formed from a polycarboxylic acid and at least one of the oligomer or polymer arms comprises a reaction product of reactants including a C11-C20 amino acid, a C11-C20 lactam, or a mixture thereof;

selectively melting at least a portion of the powder layer; and

forming a three-dimensional article by applying one or more additional layers to a preceding layer,

wherein the sinterable powder composition has a melt enthalpy of less than 100 J/g and a sintering window of less than 40° C.

20. The method of claim 19 , further comprising:

using residual powder composition from forming the three-dimensional article in a selective sintering process to produce a second three-dimensional article that does not exhibit orange peel.

21. A three-dimensional article comprising:

a plurality of sintered layers including a polymer matrix;

wherein one or more branched polyamide star polymers comprise at least 5 weight percent of the polymer matrix,

wherein at least one of the star polymers comprises a single branching unit and at least 3 oligomer or polymer arms covalently attached to the branching unit;

wherein the single branching unit is formed from a polycarboxylic acid;

wherein the branched polyamide includes:

a nylon-11 branch unit, a nylon-12 branch unit, or a combination thereof, or

polyamide branch units formed from laurolactam, aminoundecanoic acid, or a mixture thereof; and

wherein the polymer matrix has a melt enthalpy of less than 100 J/g and a sintering window of less than 40° C.

22. A powder composition, comprising:

a laser-sinterable powder that includes at least 40 weight percent of one or more branched polyamide star polymers having a number of average molecular weight of at least 8,000, wherein the one or more branched polyamides include a single branching unit that is attached, via amide linkages, to at least three branch units,

wherein the single branching unit is formed from a polycarboxylic acid,

wherein the branched polyamide includes:

a nylon-11 branch unit, a nylon-12 branch unit, or a combination thereof, or

polyamide branch units formed from laurolactam, aminoundecanoic acid, or a mixture thereof; and

wherein the powder composition has a melt enthalpy of less than 100 J/g and a sintering window of less than 40° C.