Thermoplastic polymer powder for selective laser sintering (SLS)

Abstract

The present invention relates to a thermoplastic polymer powder and to the use thereof as material for selective laser sintering (SLS). The polymer powder contains a partially crystalline polymer, an amorphous polymer and a compatibilizing agent, and optionally additional additives and/or auxiliary substances, wherein the partially crystalline polymer, the amorphous polymer and the compatibilizing agent are in the form of a polymer blend. The invention also relates to a method for producing the thermoplastic polymer powder and to a method of selective laser sintering (SLS).

Claims

1. A thermoplastic polymer powder P comprising (A) from 10 to 89.9% by weight, based on the entire polymer powder P, of at least one semicrystalline polymer A; (B) from 10 to 89.9% by weight, based on the entire polymer powder P, of at least one amorphous polymer B, where the amorphous polymer B is at least one polymer selected from the group consisting of styrene-butadiene block copolymers, acrylonitrile-butadiene-styrene copolymers, styrene-acrylonitrile copolymers, α(alpha)-methylstyrene-acrylonitrile copolymers, acrylate-styrene-acrylonitrile copolymers, methyl methacrylate-acrylonitrile-butadiene-styrene copolymers, methyl methacrylate-butadiene-styrene copolymers, styrene-methyl methacrylate copolymers, amorphous polystyrene, and impact-modified polystyrene; (C) from 0.1 to 15% by weight, based on the entire polymer powder P, of at least one compatibilizer C, selected from the group consisting of styrene-acrylonitrile-maleic anhydride terpolymers, styrene-N-phenylmaleimide-maleic anhydride terpolymers, and methylmethacrylate-maleic anhydride copolymers; (D) optionally from 0 to 5% by weight, based on the entire polymer powder P, of at least one additive and/or auxiliary; where the sum of the % s by weight of components A, B, C, and optionally D is 100% by weight; where the semicrystalline polymer A, the amorphous polymer B, and the compatibilizer C are present in the form of a polymer blend; and where the D.sub.50 median particle diameter of the thermoplastic powder P is in the range from 5 to 200 μm.

2. The thermoplastic polymer powder P of claim 1, wherein the semicrystalline polymer A is at least one polymer selected from the group consisting of polyamides, polyetherketones, polylactides, polybutyleneterephthalate, polyethylene, polypropylene, and syndiotactic polystryene.

3. The thermoplastic polymer powder P of claim 1, wherein the semicrystalline polymer A is at least one polyamide selected from the group consisting of PA6 (polycaprolactam); PA6,6 (polyhexamethyleneadipamide); PA4,6 (polytetramethyleneadipamide); PA5,10 (polypentamethyleneadipamide); PA6,10 (polyhexamethylenesebacamide); PA7 (polyeneantholactam); PA11 (polyundecanolactam); and PA12 (polylaurolactam).

4. The thermoplastic polymer powder P of claim 1, wherein the amorphous polymer B is at least one styrene polymer or styrene copolymer which has a volume melt flow index in the range from 2 to 60 cm.sup.3/10 min, measured in accordance with ISO 1133, at 220° C. and with a load of 10 kg.

5. The thermoplastic polymer powder P of claim 1, wherein the D.sub.90 particle diameter of the polymer powder P is less than 200 μm.

6. The thermoplastic polymer powder P of claim 1, comprising (A) from 30 to 66% by weight, based on the entire polymer powder P, of at least one polyamide selected from the group consisting of polycaprolactam PA6; polyhexamethyleneadipamide PA6,6; polyundecanolactam PA11; and polylaurolactam PA12, as semicrystalline polymer A; (B) from 30 to 66% by weight, based on the entire polymer powder P, of at least one polymer selected from the group consisting of styrene-butadiene block copolymers, acrylonitrile-butadiene-styrene copolymers, styrene-acrylonitrile copolymers, α(alpha)-methylstyrene-acrylonitrile copolymers, acrylate-styrene-acrylonitrile copolymers, methyl methacrylate-acrylonitrile-butadiene-styrene copolymers, methyl methacrylate-butadiene-styrene copolymers, styrene-methyl methacrylate copolymers, amorphous polystyrene, and impact-modified polystyrene, as amorphous polymer B; (C) from 4 to 10% by weight, based on the entire polymer powder P, of a styrene-acrylonitrile-maleic anhydride terpolymer with maleic anhydride content in the range from 0.4 to 3% by weight, based on the entire terpolymer, as compatibilizer C; (D1) from 0.1 to 3% by weight, based on the entire polymer powder P, of at least one silicon dioxide nanoparticle powder or silicone additive as powder-flow aid; and (D2) optionally from 0 to 3% by weight, based on the entire polymer powder P, of at least one further additive and/or auxiliary as further component D.

7. A process for the production of a thermoplastic polymer powder P of claim 1, comprising the following steps: i) provision of a solid mixture comprising components A, B, C, and optionally D; ii) mechanical comminution of the solid mixture, whereupon a thermoplastic polymer powder P is obtained which has a D.sub.50 median particle diameter in the range from 5 to 200 μm.

8. The process of claim 7, wherein step i) comprises the mixing of components A, B, and C in the liquid state at a temperature in the range from 200 to 250° C.

9. The process of claim 7, wherein the mechanical comminution of the solid mixture in step ii) is achieved by grinding, micronizing, freeze-grinding, or jet-milling.

10. A process for the production of a three-dimensional component by selective laser sintering comprising the steps of: x) provision of a powder layer consisting of the thermoplastic polymer powder P of claim 1 in a construction chamber; xi) localized melting by a directed beam of electromagnetic radiation, followed by solidification of the thermoplastic polymer powder P in a defined region; where the steps x) and xi) are repeated so that a three-dimensional component is obtained layer-by-layer via bonding of the regions of the molten and resolidified polymer.

11. The process of claim 10, wherein the thickness of the powder layer is in the range from 100 to 200 μm.

12. The process of claim 10, wherein the process involves the production of a transparent or translucent component.

Description

EXAMPLES

(1) 1.1 Components Used

(2) The following semicrystalline polymers A1 to A4 were used as component A: A1 PA12 (Vestosint® 1111, Evonik, Germany) A2 PA6 (Ultramid® B3, BASF SE, Ludwigshafen), A3 PLA (Ingeo 2500HP, NatureWorks) and A4 Syndiotactic polystyrene (XAREC, Idemitsu, Japan)

(3) Component B1 used is Terluran® (INEOS Styrolution, Frankfurt), a free-flowing, impact-resistant acrylonitrile-butadiene-styrene polymer (ABS) with a melt volume flow rate (220° C./10 kg load, ISO 1133) of about 35 cm.sup.3/10 min.

(4) Component B2 used is Luran® (INEOS Styrolution, Frankfurt), a free-flowing, impact-resistant styrene-acrylonitrile copolymer (SAN) with a melt volume flow rate (220° C./10 kg load, ISO 1133) of about 7 cm.sup.3/10 min.

(5) Component B3 used is an impact-resistant amorphous polystyrene (HIPS) (INEOS Styrolution, Frankfurt) with a melt volume flow rate (220° C./10 kg load, ISO 1133) of about 4 cm.sup.3/10 min.

(6) Component C used is an acrylonitrile-maleic anhydride terpolymer (SAN MA) with a proportion of 2.1% by weight of maleic anhydride (INEOS Styrolution).

(7) Semicrystalline component A, amorphous component B and the compatibilizer C are mixed in a twin-screw extruder at a melt temperature of from 240° C. to 260° C. The resultant compounded material is pelletized after cooling and solidification of the melt.

(8) The resultant solid polymer mixtures are micronized by conventional processes, for example by grinding, cryogenic grinding, jet-milling or other known processes. They are tested for suitability for selective laser sintering.

(9) Table 1 below collates the polymer mixtures.

(10) TABLE-US-00001 TABLE 1 Polymer powder compositions Test A1 A2 A3 A4 B1 B2 B3 C P1 35 60 5 P2 35 60 5 P3 35 60 5 P4 35 60 5 P5 47.5 47.5 5 P6 47.5 47.5 P7 47.5 47.5 5 P8 47.5 47.5 P9 47.5 47.5 5 P10 47.5 47.5 5 P11 47.5 47.5 5 P12 60 35 5 P13 60 35 5 P14 60 35 5 P15 60 35 5 V1 37.5 67.5 0 V2 50 50 0 V3 67.5 37.5 0

(11) The compositions V1 to V3 are comparative examples (without addition of the compatibilizer C).

(12) Various selective laser sintering processes were carried out with these compositions.