Polyamide powder for selective sintering methods
A polyamide powder for selective absorbing sintering, SAS, or selective inhibition sintering, SIS. The polyamide powder has a solution viscosity to ISO 307 of 1.8 to 2 and a rise in the solution viscosity of 0% to 25% when it is subjected to a temperature 20° C. below its melting temperature under air for 20 hours.
1. A polyamide powder for selective absorbing sintering, SAS, or selective inhibition sintering, SIS, wherein the polyamide has a solution viscosity to ISO 307 of 1.8 to 2, a rise in the solution viscosity of 5% to 25%, when subjected to a temperature 20° C. below its melting temperature under air for 20 hours, and an excess of carboxylic acid end groups over amine end groups of 20 to 60 mmol/kg,
wherein a surface energy of the polyamide, determined by a contact angle measurement by a capillary rise height method by use of the Washburn equation and the evaluation method according to Owens, Wendt, Rabel and Kaelble, is not more than 35 mN/m and
a BET surface area of the polyamide powder, measured to DIN ISO 9277, is from 10 m 2 /g to 30 m 2 /g.
2. The polyamide powder according to claim 1 , wherein the polyamide has a rise in solution viscosity of 5 to 15% when subjected to a temperature 20° C. below its melting temperature under air for 20 hours.
3. The polyamide powder according to claim 1 , wherein the excess is achieved by dicarboxylic acids.
4. The polyamide powder according claim 1 , wherein the powder has open mesopores and the cumulative pore volume distribution of the mesopores, measured to DIN 66134, is at least 0.01 cm 3 /g.
5. The polyamide powder according to claim 1 , wherein the polyamide powder absorbs liquid in a volume of 1,000 pl/g to 30,000 pl/g.
6. The polyamide powder according to claim 1 , wherein a weight-average particle diameter d 50 of the polyamide powder, measured by laser diffraction, is not more than 100 μm.
7. The polyamide powder according to claim 1 , wherein a weight-average particle diameter d 50 of the polyamide powder, measured by laser diffraction, is from 10 μm to 80 μm.
8. The polyamide powder according to claim 1 , wherein a bulk density of the polyamide powder, measured to DIN 53466, is between 300 g/l and 600 g/l.
9. The polyamide powder according to claim 1 , wherein a surface energy of the polyamide, determined by a contact angle measurement by a capillary rise height method by use of the Washburn equation and the evaluation method according to Owens, Wendt, Rabel and Kaelble, is from 25 mN/m to 32 mN/m.
10. The polyamide powder according to claim 1 , wherein the polyamide powder is obtained by a precipitation process.
11. Shaped bodies which are obtained at least partly from the polyamide powder according to claim 1 .
12. The polyamide powder according to claim 10 , wherein a suspension obtained by precipitation is left at a temperature of 2-4 K above the precipitation temperature for 10 to 180 min, after precipitation.