Polyamide-based polymer powder, use thereof in a molding method, and molded articles made from said polymer powder
Disclosed herein is a polymer powder containing a polyamide of AB type, produced by polymerizing at least one lactam having from 10 to 12 carbon atoms in a monomer unit or by polycondensing at least one corresponding ω-aminocarboxylic acid having from 10 to 12 carbon atoms in a monomer unit, and a polyamide of AABB type, produced by polycondensing at least one diamine and at least one dicarboxylic acid having respectively from 10 to 14 carbon atoms in monomer units. The polyamide of the AB type and the polyamide of the AABB type are prepared separately and then coprecipitated to form the polymer powder, and the polymer powder is a physical mixture of the polyamide of the AB type and the polyamide of the AABB type. Also disclosed herein is a method for producing the polymer powder.
1. A polymer powder, comprising:
a polyamide of AB type, produced by polymerizing at least one lactam having from 10 to 12 carbon atoms in a monomer unit or by polycondensing at least one corresponding ω-aminocarboxylic acid having from 10 to 12 carbon atoms in a monomer unit; and
a polyamide of AABB type, produced by polycondensing at least one diamine and at least one dicarboxylic acid having respectively from 10 to 14 carbon atoms in monomer units,
wherein:
the polyamide of the AB type and the polyamide of the AABB type are prepared separately and then coprecipitated to form the polymer powder;
the polymer powder is a physical mixture of the polyamide of the AB type and the polyamide of the AABB type; and the polymer powder has a melting point of 186° C. or higher.
2. The polymer powder of claim 1 , comprising at least nylon-11 or nylon-12 and at least one homopolyamide based on PA1010, PA1012, PA1212 or PA1013.
3. The polymer powder of claim 1 , comprising the polyamide of the AB type and the polyamide of the AABB type in a ratio by mass, AB:AABB, of from 98:2 to 2:98.
4. The polymer powder of claim 1 , wherein a relative solution viscosity of the polymer powder is from 1.4 to 2.1, measured in a 0.5% by weight solution in m-cresol in accordance with ISO 307.
5. The polymer powder of claim 1 , wherein an average particle size of the polymer powder is from 10 to 250 μm.
6. The polymer powder of claim 1 , further comprising an auxiliary, a filler, or both.
7. The polymer powder of claim 1 , wherein the polyamide of the AB type is produced by polymerizing at least one lactam having from 10 to 12 carbon atoms in a monomer unit.
8. The polymer powder of claim 1 , wherein the polyamide of the AB type is produced by polycondensing at least one ω-aminocarboxylic acid having from 10 to 12 carbon atoms in a monomer unit.
9. The polymer powder of claim 1 , comprising the polyamide of the AB type and the polyamide of the AABB type in a ratio by mass, AB:AABB, of from 50:50 to 95:5.
10. The polymer powder of claim 1 , comprising the polyamide of the AB type and the polyamide of the AABB type in a ratio by mass, AB:AABB, of from 85:15 to 95:5.
11. The polymer powder of claim 1 , which exhibits an enthalpy of fusion of from 117 to 137 J/g.
12. A molding obtained from the polymer powder of claim 1 by a direct progressive construction process.
13. The molding of claim 12 , wherein the molding is produced by a layer-by-layer process in which regions of a respective powder layer are melted selectively by introducing electromagnetic energy, and the selectivity is achieved by: applying at least one susceptor, at least one inhibitor, or at least one absorber to the respective powder layer; applying at least on mask to the respective powder layer; or focusing a laser beam on the regions of the respective powder layer.
14. A process for producing the polymer powder of claim 1 , the process comprising: codissolving the polyamide of the AB type and the polyamide of the AABB type by heating in an alcohol having from 1 to 3 carbon atoms; lowering the temperature in one or more stages to a temperature at which a copolyamide precipitates; isolating the copolyamide from the solvent and drying the copolyamide; and optionally mixing an auxiliary, a filler, or both, into the powder.
15. The process of claim 14 , comprising: codissolving the polyamide of the AB type and the polyamide of the AABB type under an autogenous pressure at a temperature of from 130° C. to 180° C. and then
lowering the temperature in one or more stages to from 90° C. to 128° C.
16. The process of claim 14 , wherein, after the codissolving, the temperature is maintained at from 110° C. to 128° C. for 10 minutes to 3 hours and then the temperature is lowered in one or more further stages to from 90° C. to 118° C.
17. A process for producing moldings by a layer-by-layer process, the process comprising performing a selective melting of regions of a respective polymer powder layer by introducing electromagnetic energy, wherein the respective polymer powder layer comprises the polymer powder of claim 1 .
18. The process of claim 17 , wherein the selective melting is achieved by: applying at least one susceptor, at least one inhibitor, or at least one absorber to the respective polymer powder layer; applying at least one mask to the respective polymer powder layer; or on the regions of the respective polymer powder layer.