Polyester powder compositions, methods and articles
Powder compositions and articles and methods of forming articles from powder compositions are provided. In one embodiment the powder compositions include at least one polyester polymer powder and an amount of reinforcing particles having an aspect ratio of preferably at least about 5:1. In another embodiment the ponder compositions include at least one medium-high melting temperature, aromatic and crystalline polyester polymer powder. In a preferred embodiment, the powder composition is capable of being formed, via a laser sintering process, into a three-dimensional article that exhibits one or more desirable mechanical properties in an elevated temperature environment.
1. A method comprising:
providing a powder composition; and
selectively laser sintering the powder composition to form a three-dimensional article,
wherein the powder composition comprises at least one laser-sinterable polymer powder, and at least 3 weight percent of reinforcing particles having an aspect ratio of at least 5:1and a maximum dimension of less than 300 microns, based on the total weight of the powder composition,
wherein at least a portion of the reinforcing particles are mineral particles that form at least 1 weight percent of the powder composition, based on the total weight of the powder composition, and
wherein at least some of the reinforcing particles are acicular.
2. The method of claim 1 , wherein the mineral particles form at least 3 weight percent of the powder composition, based on the total weight of the powder composition.
3. The method of claim 1 , wherein the reinforcing particles have an aspect ratio of at least 20:1.
4. The method of claim 1 , wherein the mineral particles comprise a silicate.
5. The method of claim 1 , wherein the mineral particles comprise wollastonite.
6. The method of claim 1 , wherein the reinforcing particles have a maximum dimension of greater than 10 microns.
7. The method of claim 1 , wherein the at least one laser-sinterable polymer powder comprises a polyester and a polyamide, a polyolefin, a polyetherketone, a polyurethane, a polyvinyl alcohol, a polyether, a polyvinyl acetate, a polymethacrylate, a phenolic, an ionomer, a polyacetal, an acrylonitrile-butadiene-styrene copolymer, a polyimide, a polycarbonate, or a mixture thereof.
8. The method of claim 7 , wherein the at least one laser-sinterable polymer powder comprises a polyamide.
9. The method of claim 8 , wherein the mineral particles comprise wollastonite.
10. The method of claim 1 , wherein the powder composition is laser sintered to form a test specimen, and the reinforcing particles are present in an amount sufficient to increase the heat deflection temperature in accordance with Method A of ISO 75-2:2004 of the test specimen by at least 10° C. relative to a reference test specimen produced by laser sintering the at least one polymer powder in the absence of the reinforcing particles.
11. The method of claim 1 , wherein, when the powder composition is laser sintered to form a test specimen, the test specimen has a heat deflection temperature in accordance with Method A of ISO 75-2:2004 of at least 130° C.
12. The method of claim 1 , wherein, when the powder composition is laser sintered to form a test specimen, the test specimen has a tensile strength in accordance with ISO 527 of at least 40 MPa.
13. The method of claim 1 , wherein providing the powder composition comprises
melt blending:
the reinforcing particles, and
the at least one polymer powder or pellets containing the material of the at least one polymer powder; and
forming the powder composition from the resulting blend.
14. A three-dimensional article prepared by the method of claim 1 .