Radiation-curable composition containing mercapto-functional polyorganosiloxanes for additive-manufacturing technology

1. A radiation-curable silicone composition for additive-manufacturing technology comprising

mercapto-functional polyorganosiloxane(s) as Component A,

organosiloxane(s) with at least two aliphatic unsaturated carbon-carbon moieties as Component B,

photo-initiator(s) as Component C for initiating a curing reaction between Component A and Component B,

dye(s) as Component D dissolved in mercapto-functional polyorganosiloxane(s) as Component E, the mercapto-functional polyorganosiloxane(s) having a fraction of (mercaptoalkyl)methylsiloxane units of at least 50 mol %,

wherein Component D is dissolved in Component E before Component D is combined with the other components of the radiation-curable silicone composition.

2. The radiation-curable silicone composition according to claim 1 , wherein the dye is characterized by the following features alone or in combination:

solubility: at least 0.5 wt. % at 50° C. in polyethylene glycol with an Mn of 400 g/mol;

having a light absorption maximum in the range of 460 to 600 nm;

comprising a perylene moiety;

color: red, orange or yellow;

amount: being present in an amount of 0.001 to 1 wt. % with respect to the weight of the whole radiation-curable composition.

3. The radiation-curable silicone composition according to claim 1 , wherein the mercapto-functional polyorganosiloxane according to Component A is characterized by the following features alone or in combination:

fraction of (mercaptoalkyl)methylsiloxane units: 7-100 mol-%;

being characterized by the following formula:

[(CH 3 ) 2 RSiO 1/2 ] w [(CH 3 ) 3 SiO 1/2 ] x [(CH 3 ) 2 SiO] y [R(CH 3 )SiO] z ,

with w being 0 to 0.1, x being 0 to 0.1 and w+x being 0.01 to 0.1; y being 0 to 0.93, z being 0.07 to 0.99, wherein each R is independently selected from a mercapto C 1-10 hydrocarbyl group;

molecular weight (Mn): 500 to 20,000 g/mol;

viscosity: 10 to 1,000 mPa*s at 23° C.;

amount: being present in the composition of 0.5 to 50 wt. % with respect to the weight of the whole radiation-curable composition.

4. The radiation-curable silicone composition according to claim 1 , the organosiloxane(s) with at least two aliphatic unsaturated carbon-carbon moieties being characterized by the following features alone or in combination:

structure:

wherein R independently represent a non-substituted or substituted, monovalent hydrocarbon group with 1 to about 6 C atoms and wherein n is in the range of 3 to 10,000

viscosity: 1 to 90,000 mPa*s at 23° C.;

amount: being present in an amount of 10 to 98 wt. % with respect to the weight of the whole radiation-curable composition.

5. The radiation-curable silicone composition according to claim 1 , the organosiloxane(s) with at least two aliphatic unsaturated carbon-carbon moieties comprising a QM resin containing vinyl groups, which is further characterized by the following features alone or in combination:

concentration of unsaturated moieties: at least 0.15 mmol/g;

viscosity: 500 to 90,000 mPa*s at 23° C.;

amount: being present in an amount of 10 to 98 wt. % with respect to the weight of the whole radiation-curable composition.

6. The radiation-curable silicone composition according to claim 1 comprising two kinds of organosiloxane(s) with at least two aliphatic unsaturated carbon-carbon moieties,

a first organosilane with at least two aliphatic unsaturated carbon-carbon moieties being characterized by the following features alone or in combination;

structure:

wherein R independently represent a non-substituted or substituted, monovalent hydrocarbon group with 1 to about 6 C atoms and wherein n is in the range of 3 to 10,000

viscosity: 1 to 90,000 mPa*s at 23° C.;

amount: being present in an amount of 10 to 98 wt. % with respect to the weight of the whole radiation-curable composition, and

a second organosilane with at least two aliphatic unsaturated carbon-carbon moieties comprising a QM resin containing vinyl groups, which is further characterized by the following features alone or in combination:

concentration of unsaturated moieties: at least 0.15 mmol/g;

viscosity: 500 to 90,000 mPa*s at 23° C.;

amount: being present in an amount of 10 to 98 wt. % with respect to the weight of the whole radiation-curable composition.

7. The radiation-curable silicone composition according to claim 1 not containing a surfactant for dissolving the dye(s).

8. The radiation-curable silicone composition for use in an additive-manufacturing technology in particular according to claim 1 comprising

mercapto-functional polyorganosiloxane(s) as Component A

being present in an amount of 0.5 to 50 wt. %, and

having a fraction of (mercaptoalkyl)methylsiloxane units of 7 to 100 mol-%;

organosiloxane(s) with at least two aliphatic unsaturated carbon-carbon moieties as Component B,

being present in an amount of 10 to 98 wt. %, and

having a viscosity of 1 to 90,000 mPa*s,

photo-initiator(s) as Component C,

being present in an amount of 0.01 to 5 wt. %, and

having a light absorption band in the range of 300 to 450 nm,

dye(s) as Component D dissolved in mercapto-functional polyorganosiloxane(s) as Component E, the mercapto-functional polyorganosiloxane(s) having a fraction of (mercaptoalkyl)methylsiloxane units of at least 50 mol %,

the dye(s) being present in an amount of 0.001 to 1 wt. %,

having a light absorption maximum in the range of 460 to 600 nm, and

having a solubility of less than 1 g in 100 g water at 23° C.,

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

9. A process of producing the radiation-curable composition as described in claim 1 , the process comprising the steps of

providing a solution of dye(s) according to Component D as described in claim 1 a composition comprising mercapto-functional polyorgano-siloxane(s) having a fraction of (mercaptoalkyl)methylsiloxane units of at least 50 mol % according to Component E,

combining the solution containing the dye(s) dissolved in the mercapto-functional polyorganosiloxane(s) with

mercapto-functional polyorganosiloxane(s) according to Component A, organosiloxane(s) with at least two aliphatic unsaturated carbon-carbon moieties according to Component B,

photo-initiator(s) according to Component C for initiating a curing reaction between Component A and Component B,

optionally filler(s), stabilizer(s) and additive(s).

10. A process of producing a cured 3-dimensional article, the process comprising the step of processing the curable composition as described in claim 1 by applying an additive-manufacturing technique comprising a radiation curing step.

11. The process according to the claim 10 , wherein the radiation curing step is carried out within a wave length range of 350 to 420 nm.

12. A cured 3-dimensional article obtained or obtainable by radiation curing the radiation-curable composition of claim 1 .

13. The cured 3-dimensional article as described in claim 12 being characterized by the following features alone or in combination:

being rubber-elastic;

having a Shore hardness A of 30 to 90 according to DIN/EN 53505 (2000 August);

having a tensile strength of 0.5 to 50 MPa according to DIN/EN 53504 (2017 March);

having an elongation at break of 10 to 1,000% according to DIN/EN 53504 (2017 March).

14. The cured 3-dim article as described in claim 12 having the shape of a protection mask, inhaler mask, night guard, mouth guard, respirator, hearing protection, fitting, orthodontic or dental appliances, or part thereof or for use as shock absorber or seal.

15. A kit of parts comprising

the radiation-curable silicone composition as described in claim 1 ; and

additive-manufacturing equipment.