Polyamide-based polymer powder, use thereof in a molding method, and molded articles made from said polymer powder

Abstract

The invention relates to a polymer powder for use in a layer-by-layer method in which areas of each powder layer are selectively fused by introducing electromagnetic energy. Said polymer powder contains: at least one AB-type polyamide produced by polymerizing lactams comprising 10 to 12 carbon atoms in the monomer unit or polycondensing the corresponding ω-amino carboxylic acids comprising 10 to 12 carbon atoms in the monomer unit and at least one AABB-type polyamide produced by polycondensing diamines and dicarboxylic acids, each of which comprises 10 to 14 carbon atoms in the monomer units, the AB-type polyamide containing up to 20 mole % of the AABB comonomer units and the AABB-type polyamide containing up to 20 mole % of the AB monomer units. The invention also relates to a method for producing such a powder, a layer-by-layer method for producing a molded article from such a powder in which areas of each layer are selectively fused by introducing electromagnetic energy, the selectivity being obtained using masks or by applying inhibitors, absorbers or susceptors or focusing the applied energy, and molded articles produced in said manner.

1 . A polymer powder, comprising:
 a polyamide of the 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 the AABB type, produced by polycondensing at least one diamine and at least one dicarboxylic acid having respectively from 10 to 14 carbon atoms in a monomer units,   wherein:   the polyamide of the AB type optionally comprises up to 20 mol % of AABB comonomer units; and   the polyamide of the AABB type optionally comprises up to 20 mol % of AB monomer units.   
     
     
         2 . The polymer powder of  claim 1 , wherein the powder is obtained by coprecipitation of at least one polyamide of the AB type and of at least one polyamide of the AABB type. 
     
     
         3 . 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. 
     
     
         4 . The polymer powder of  claim 1 , wherein the polyamide of the AB type optionally comprises up to 10 mol % of the AABB comonomer units and the polyamide of the AABB type optionally comprises up to 10 mol % of the AB monomer units. 
     
     
         5 . 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 of from 98:2 to 2:98. 
     
     
         6 . The polymer powder of  claim 1 , wherein a relative solution viscosity of the powder is from 1.4 to 2.1, measured in a 0.5% by weight solution in m-cresol in accordance with ISO 307. 
     
     
         7 . The polymer powder of  claim 1 , wherein an average particle size of the powder is from 10 to 250 μm. 
     
     
         8 . The polymer powder of  claim 1 , further comprising a auxiliary, a filler, or both. 
     
     
         9 . 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, drying the copolyamide, or both isolating and drying, to form a powder; and   optionally mixing an auxiliary, a filler, or both, into the powder.   
     
     
         10 . The process of  claim 9 , 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.   
     
     
         11 . The process of  claim 9 , 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. 
     
     
         12 . A process for producing moldings by a layer-by-layer process, the process comprising selectively melting regions of a respective polymer powder layer by introducing electromagnetic energy, wherein the respective polymer powder layer comprises the polymer powder of  claim 1 . 
     
     
         13 . The process of  claim 12 , wherein selective melting is achieved by applying susceptors, inhibitors, or absorbers, or by masks, or by focusing a laser beam. 
     
     
         14 . A molding obtained from the polymer powder of  claim 1  by a direct progressive construction process. 
     
     
         15 . The molding of  claim 14 , 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 susceptors, inhibitors, or absorbers, or by masks, or by focusing a laser beam. 
     
     
         16 . The polymer powder of  claim 1 , comprising a polyamide of the AB type, produced by polymerizing at least one lactam having from 10 to 12 carbon atoms in a monomer unit. 
     
     
         17 . The polymer powder of  claim 1 , comprising a polyamide of the AB type, produced by polycondensing at least one ω-aminocarboxylic acid having from 10 to 12 carbon atoms in a monomer unit. 
     
     
         18 . The polymer powder of  claim 1 , wherein the polyamide of the AB type comprises up to 20 mol % of AABB comonomer units. 
     
     
         19 . The polymer powder of  claim 1 , wherein the polyamide of the AABB type comprises up to 20 mol % of AB monomer units. 
     
     
         20 . The polymer powder of  claim 2 , wherein the polyamide of the AB type optionally comprises up to 10 mol % of the AABB comonomer units and the polyamide of the AABB type optionally comprises up to 10 mol % of the AB monomer units.