Use of moulding compounds based on blends of san-copolymers and polyamide for 3D printing

1. A method of producing a three-dimensional object by 3D printing, comprising the steps of:

providing a thermoplastic molding composition consisting of a mixture of the components A to E:

A: 35 to 60 wt % of at least one impact-modified polymer A, consisting of the components a and b:

a: 30 to 95 wt % of at least one styrene-acrylonitrile copolymer a having an average molar mass Mw of 150 000 to 350 000 g/mol, obtained by polymerization of:

a1: 18 to 35 wt % of acrylonitrile (AN), and

a2: 82 to 65 wt % of styrene (S); and

b: 5 to 70 wt % of at least one graft copolymer b as impact modifier, with

b1: 45 to 85 wt % of a graft base b1, obtained by polymerization of:

 b11: 80 to 100 wt % of 1,3-butadiene, and

 b12: 0 to 20 wt % of styrene; and

b2: 15 to 55 wt % of a graft b2, obtained by polymerization of:

 b21: 70 to 90 wt % of styrene; and

 b22: 10 to 30 wt % of acrylonitrile;

B: 33 to 58 wt % of at least one polyamide B selected from the following: polyamide 6 (polycaprolactam), polyamide 6,6 (polyhexamethyleneadipamide), polyamide 4,6 (polytetramethyleneadipamide), polyamide 5,10 (polypentamethyleneadipamide), polyamide 6,10 (polyhexamethylenesebacamide), polyamide 7 (polyenantholactam), polyamide 11 (polyundecanolactam), and polyamide 12 (polydodecanolactam);

C: 1 to 10 wt % of at least one compatibilizer C based on a styrene-acrylonitrile-maleic anhydride terpolymer obtained by polymerization of:

C1: 72 to 84.5 wt % of styrene;

C2: 15 to 27.5 wt % of acrylonitrile; and

C3: 0.5 to 5 wt % of maleic anhydride;

D: 0.01 to 5 wt % of one or more auxiliaries selected from the following: stabilizers, oxidation retarders, agents against thermal decomposition and decomposition by ultraviolet light, lubricants and mold release agents, processing assistants, and plasticizers; and

E: 0 to 30 wt % of one or more further additives E;

where the sum of the components A, B, C, D, and, if present, E makes 100 wt %;

fluidizing the thermoplastic molding composition;

extruding the thermoplastic molding composition;

applying a plurality of layers of the thermoplastic molding composition to a base or to a preceding layer of the thermoplastic molding composition; and

consolidating the thermoplastic molding composition to produce the three-dimensional object.

2. A method of claim 1 , wherein the viscosity (measured to ISO 11443:2014) of the molding composition at shear rates of 1 to 10 1/s and at temperatures of 250° C. is not more than 1×10 5 Pa*s and the melt volume rate (MVR, measured to ISO 1133-1:2011 at 240° C. and 10 kg load) of the molding composition is more than 15 ml/10 min.

3. A method of claim 1 , wherein component B is polyamide 6.

4. A method of claim 1 , wherein the thermoplastic molding composition consists of:

35 to 50 wt % of component A,

40 to 58 wt % of component B,

1 to 10 wt % of component C,

0.01 to 5 wt % of component D, and

0 to 20 wt % of component E.

5. A method of claim 1 , wherein the thermoplastic molding composition consists of:

35 to 50 wt % of component A,

45 to 58 wt % of component B,

1 to 10 wt % of component C,

0.01 to 5 wt % of component D, and

0 to 10 wt % of component E.

6. A method of claim 1 , wherein the thermoplastic molding composition consists of:

40 to 50 wt % of component A,

45 to 55 wt % of component B,

2 to 6 wt % of component C,

0.05 to 3 wt % of component D, and

0 to 10 wt % of component E.

7. A method of claim 1 , wherein in the impact-modified polymer A, the fraction of component a is 30 to 60 wt % and the fraction of the graft copolymer b used as impact modifier is 70 to 40 wt %.

8. A method of claim 1 , wherein at least one graft copolymer b is used with:

50 to 80 wt % of a graft base b1 obtained by polymerization of:

b11: 100 wt % of butadiene; and

20 to 50 wt % of a graft b2 obtained by polymerization of:

b21: 70 to 90 wt % of styrene, and

b22: 10 to 30 wt % of acrylonitrile.

9. A method of claim 1 , wherein the particle size (d 50 ) of the graft copolymer b is at least 80 nm and at most 1 μm.

10. A method of claim 1 , wherein the three-dimensional object are bridges.

11. A method of claim 7 , wherein in the impact-modified polymer A, the fraction of component a is 40 to 60 wt %, and the fraction of the graft copolymer b used as impact modifier is 60 to 40 wt %.

12. A method of claim 8 , wherein the at least one graft copolymer b is used with:

50 to 80 wt % of a graft base b1 obtained by polymerization of:

b11: 100 wt % of butadiene; and

20 to 50 wt % of a graft b2 obtained by polymerization of:

b21: 72.5 to 85 wt % of styrene, and

b22: 15 to 27.5 wt % of acrylonitrile.

13. A method of claim 9 , wherein the particle size (d 50 ) of the graft copolymer b is 100 nm to 600 nm.