Coloured curable composition for additive manufacturing processes, 3-dim composite article and use thereof

1. A coloured curable composition for use in an additive manufacturing process, the composition comprising:

a curable resin composition comprising radiation curable components,

a photo initiator,

a dye composition comprising a dye D1 and a dye D2,

dye D1 having a light absorption maximum within a wave length range from 400 to 530 nm,

dye D2 showing a light absorption maximum within a wave length range from 540 to 650 nm.

2. The coloured curable composition of claim 1 , wherein either dye D1 or dye D2 or dye D1 and dye D2 have an additional light absorption within a wave length range from 300 to 400 nm with an intensity being at least 20% compared to the intensity of the light absorption of the respective dye(s) within a wave length range from 400 to 650 nm.

3. The curable composition of claim 1 , being characterized by one or more of the following features:

viscosity: less than 200 mPa*s at 23° C.;

light absorption in the range from 400 to 650 nm: more than 90% for a path length of 5 mm;

light transmission: less than 25% for a path length of 1 mm;

colour impression: deeply coloured for a path length of 1 mm or more;

pH value if the curable composition is brought in contact with wet pH sensitive paper: 6-8;

optionally combustible within a temperature range from 600 to 900° C. without residues.

4. The curable composition of claim 1 , the photo initiator being characterized by one or more of the following features:

showing a light absorption band within a wave length range from 300 to 450 nm;

solubility in curable composition: at least 2 g/l at 23° C.

5. The curable composition of claim 1 , dye D1 being characterized by one or more of the following features:

molecular weight: from 50 to 1,000 g/mol;

solubility in the curable composition: at least 0.1 g/l at 23° C.;

comprising an anthraquinone moiety, azo moiety, naphthoquinolinedione moiety, isoquinoline moiety or xanthenone moiety.

6. The curable composition of claim 1 , dye D2 being characterized by one or more of the following features:

molecular weight: from 50 to 1,000 g/mol;

light absorption within a wave length range from 300 to 400 nm with an intensity being at least 20% compared to the intensity of the light absorption within a wave length range from 540 to 650 nm;

solubility in the curable composition: at least 0.05 g/l at 23° C.;

comprising an anthraquinone moiety, azo moiety, phenoxazine moiety, or triphenylmethane moiety.

7. The curable composition of claim 1 , the radiation curable component(s) comprising a backbone and reactive groups being attached to the backbone, the radiation curable component(s) being characterized by one or more of the following features (chemical):

bearing one or more (meth)acrylate moieties as reactive groups;

bearing aromatic, aliphatic, or aromatic-aliphatic moieties in the backbone;

optionally bearing one or more urethane moieties in the backbone;

optionally bearing one or more hydroxyl groups in the backbone.

8. The curable composition of claim 1 , the ratio of dye D1 to dye D2 in the curable composition being from 0.1:1 to 3:1 with respect to weight.

9. The curable composition of claim 1 comprising one or more of the following component(s):

high boiling additive(s), preferably having a boiling point above 100° C. in an amount from 1 to 20 wt. % with respect to the weight of the whole composition;

stabilizer(s), preferably in an amount from 0.001 to 1 wt. % with respect to the weight of the whole composition.

10. The curable composition of claim 1 , not comprising one or more of the following component(s):

filler(s) in an amount of more than 1 wt. %;

inorganic pigment(s) in an amount of more than 1 wt. %;

component(s) comprising elements other than C, H, O, N, S, P, Hal in an amount of more than 1 wt. %;

wt. % with respect to the weight of the whole composition.

11. The curable composition of claim 1 , comprising:

radiation curable component(s) from 50 to 98 wt. %,

photo initiator from 0.5 to 10 wt. %,

dye D1 from 0.01 to 1 wt. %,

dye D2 from 0.01 to 1 wt. %,

high boiling additive from 0 to 20 wt. %,

wt. % with respect to the weight of the whole composition.

12. The curable composition of claim 1 , comprising:

radiation curable components comprising a (meth)acrylate moiety and being present in an amount from 50 to 96 wt. %,

photo initiator comprising a phosphine oxide moiety and being present in an amount from 0.5 to 10 wt. %,

dye D1 comprising an anthraquinone moiety and being present in an amount from 0.01 to 1 wt. %,

dye D2 comprising an anthraquinone moiety and being present in an amount from 0.01 to 1 wt. %,

high boiling additive having a molecular weight from 100 to 500 g/mol and being present in an amount from 1 to 15 wt. %,

the curable composition not comprising

filler(s) in an amount of more than 1 wt. %,

inorganic pigment(s) in an amount of more than 1 wt. %,

component(s) comprising elements other than C, H, O, N, S, P, Hal in an amount of more than 1 wt. %,

wt. % with respect to the weight of the whole composition.

13. A process of producing a 3-dim article, the process comprising the step of processing the curable composition of claim 1 , by an additive manufacturing technique.

14. A 3-dim composite article obtained or obtainable of claim 1 , the article being characterized by one or more of the following features:

light transmission: less than 20% for a path length of 1 mm;

colour impression: black at a layer thickness of 2 mm or more;

hue h°: below 30 determined for a path length of 5 mm in transmission mode according to the CIELCh colour system;

chroma C*: less than 20 determined for a path length of 5 mm in transmission mode according to the CIELCh colour system;

combustible within a temperature range of 800 to 950° C. without residues.

15. A process of producing a 3-dim cast article, the process comprising:

processing the curable composition of claim 1 , in an additive manufacturing process to obtain a 3-dim composite article,

embedding the 3-dim composite article in an investment material,

replacing the material of the 3-dim composite article by a casting material to obtain a 3-dim cast article embedded in the investment material,

removing the investment material from the 3-dim cast article.

16. The composition of claim 1 , wherein dye D1 is present in an amount from 0.04 to 0.1 wt. % and dye D2 is present in an amount from 0.02 to 0.1 wt. %, each wt. % with respect to the weight of the whole composition.