权利要求：
Claims
1. A filament comprising a core material (CM) coated with a layer of shell
material (SM), wherein
the core material (CM) comprises the components a) to ¢)
a) 30 to 80% by volume, based on the total volume of the core material (CM)
of at least one inorganic powder (IP),
b) 20 to 70% by volume, based on the total volume of the core material (CM)
of at least one binder (B) comprising component b1)
b1) atleast one polymer (P)
c) 0to 20% by volume, based on the total volume of the core material (CM) of
at least one additive (A),
and the shell material(SM) comprises the components d) to f)
d) 75to 100% by volume, based on the total volume of the shell material (SM)
of at least one thermoplastic polymer (TP)
e) 0to 20% by volume, based on the total volume of the shell material (SM) of
the at least one inorganic powder (IP),
f) 0 to 25% by volume, based on the total weight of the shell material (SM) of
the at least one additive (A), wherein the thickness of the layer of shell
material is 0.05 to 0.5 mm.
2. The filament according to claim 1, wherein the binder (B)
i) comprises from 50 to 96% by weight or the at least one polymer (P), based
on the total weight of the binder, and/or
ii) the at least one polymer (P) is a polyoxymethylene (POM).
3. The filament according to any of claims 1 or 2, wherein the binder (B) in the core
material (CM) further comprises components b2) and/or b3)
b2) atleast one polyolefin (PO),
b3) at least one further polymer (FP), in case component b) is a
polyoxymethylene (POM).
4. The filament according to claim 3, wherein the binder (B) comprises 2 to 35% by
weight of component b2), based on the total weight of the binder (B), and/or from
2 to 40% by weight of component b3), based on the total weight of the binder (B).
5. The filament according to any of claims 1 to 4, wherein
i) the diameter of the filament is 1.5 to 3.5 mm, preferably 2.0 to 3.1 mm,
more preferably 2.6 to 3.0 mm, and/or
ii) the diameter of the core material is 1.5 to 3.0 mm, preferably 1.9 to
2.7 mm, more preferably 2.2 to 2.7 mm, and /or
iii) the thickness of the layer of shell material (SM) is 0.09 to 0.3 mm,
preferably 0.1 to 0.25 mm, and/or
iv) the particle size of the inorganic powder (IP) is from 0.1 to 80 ym,
preferably from 0.5 to 50 um, more preferably from 0.1 to 30 ym, and/or
v) the inorganic powder (IP) is a powder of at least one inorganic material
selected from the group consisting of a metal, a metal alloy and a ceramic
material, and/or
vi) the at least one thermoplastic polymer (TP) of the shell material (SM) is
selected from the group of polyoxymethylene (POM), polyolefins (PE) such
as polypropylene or polyethylene, polyurethanes (PU), polyamides (PA),
polyethers (PETH), polycarbonates (PC), and/or polyesters (PES) such as
polylactic acid and blends thereof.
6. The filament according to any one of claims 1 to 5, wherein the polymer (P) in
component (b1) is a polyoxymethylene (POM) copolymer which is prepared by
polymerization of
- from at least 50 mol-% of a formaldehyde source (b1a),
- from 0.01 to 20 mol-% of at least one first comonomer (b1b) of the general
formula (II)
wherein
R'to R* are each independently of one another selected from the group
consisting of H, C4-C4-alkyl and halogen-substituted C4-C4-alkyl;
RS is selected from the group consisting of a chemical bond, a (—
CR?%2aR5b-) group and a (-CR%R®%Q-) group,
wherein
R52 and R%"are each independently of one another selected from the group
consisting of H and unsubstituted or at least monosubstituted
C4-Cy-alkyl,
wherein the substituents are selected from the group consisting of F, CI, Br, OH and C;-Cs-alkyl;
n is0,1,20r3;
and
- from 0 to 20 mol-% of at least one second comonomer (b1c) selected from the group consisting of a compound of formula (lll) and a compound of formula (IV)
(lr),
(IV),
wherein
Z is selected from the group consisting of a chemical bond, an (-
O-) group and an (-O-R®-O-) group,
wherein
Re is selected from the group consisting of unsubstituted
C4-Cg-alkylene and C;-Cg-cycloalkylene.
7. The filament according to claim 3, wherein the further polymer (FP) is at least one
further polymer (FP) selected from the group consisting of a polyether, a
polyurethane, a polyepoxide, a polyamide, a vinyl aromatic polymer, a poly(vinyl
ester), a poly(vinyl ether), a poly(alkyl (meth)acrylate) and copolymers thereof.
8. A process for the preparation of a filament according to any of the claims 1 to 7,
wherein a core material (CM) is coated with a layer of a shell material (SM) by co-
extrusion of the core material (CM) with the shell material (SM).
9. A process for preparation of a three-dimensional green body, by a fused filament
fabrication process, comprising at least the steps a), b), ¢),
a) providing the filament according to any of claims 1 to 7 on a spool to a
noozle,
b) heating the filament to a temperature (Ty),
c) depositing of the heated filament obtained in step b) in a build chamber
using a layer based additive technique in order to form the three
dimensional green-body.
10. The process according to claim 9, wherein the temperature (Ty) in step b) is 140
to 240°C.
11. The process according to claim 9 or 10, whereinstep c) is followed by a step d) in
which at least a part of the binder (B) and/or at least a part of the shell material
(SM) is removed from the three-dimensional green body in order to form a three-
dimensional brown body.
12. The process according to claim 11, wherein in step d)
i) the binder (B) and/or the shell material (SM) is removed by acidic treatment
and/or
ii) the binder (B) and/or the shell material (SM) is removed at a temperature
below the melting point of the binder (B) and/or the shell material (SM).
13. The process according to any of claims 11 or 12, wherein step d) is followed by a
step e), in which the three-dimensional brown body is sintered to form a three-
dimensional sintered body.
14. A three-dimensional green-body, prepared by the process according to claim 9
or 10.
15. A three-dimensional brown-body, prepared by the process according to claim 11
or 12.
16. A three-dimensional sintered body, prepared by the process according to
claim 13.