Highly transparent silicone mixtures that can be cross-linked by light

1. A transparent silicone mixture crosslinkable under the influence of light, comprising

(A) at least one organosiloxane resin comprising units of the formulae I, II, III and IV

R 3 SiO 1/2   (I),

R 2 SiO 2/2   (II),

RSiO 3/2   (III),

SiO 4/2   (IV),

in which

R are saturated hydrocarbyl radicals optionally substituted by halogens, and having 1-40 carbon atoms, —OH, or a C 1-10 alkenyl radical

with the proviso that

at least 20 mol % of the units are selected from units of the general formulae III and IV,

at least 2 of the R radicals are alkenyl radicals having 1-10 carbon atoms and

at most 2% by weight of the R radicals are —OH radicals,

(B) at least one polyorganosiloxane containing at least two alkenyl groups per molecule and having a chain length of the longest chain of 200 to 10,000 siloxy units, in an amount of from 10 to 90 parts by weight per 100 parts of organosiloxane resin (A),

(C) at least one organosilicon compound containing at least two SiH functions per molecule and

(D) as one catalyst, MeCp(PtMe 3 ) activatable by light from 200 to 500 nm.

2. The silicone mixture of claim 1 , in which at least one organosiloxane resin (A) is an MQ silicone resin containing at least 80 mol % of units of the formulae I and IV.

3. The silicone mixture of claim 1 , in which at least one polyorganosiloxane (B) corresponds to the average formula V

R x 1 R y 2 SiO (4-x-y)/2   (V)

in which

R 1 is a monovalent, optionally halogen- or cyano-substituted C 1 -C 10 hydrocarbyl radical optionally bonded to silicon via an organic divalent group and containing aliphatic carbon-carbon multiple bonds,

R 2 is a monovalent, optionally halogen- or cyano-substituted, SiC-bonded C 1 -C 10 hydrocarbyl radical free of aliphatic carbon-carbon multiple bonds,

x is a non-negative number such that at least two R 1 radicals are present in each molecule, and

y is a non-negative number such that (x+y) is in the range from 1.9 to 2.2.

4. The silicone mixture of claim 2 , in which at least one polyorganosiloxane (B) corresponds to the average formula V

R 1 x R 2 y SiO (4-x-y)/2   (V)

in which

R 1 is a monovalent, optionally halogen- or cyano-substituted C 1 -C 10 hydrocarbyl radical optionally bonded to silicon via an organic divalent group and containing aliphatic carbon-carbon multiple bonds,

R 2 is a monovalent, optionally halogen- or cyano-substituted, SiC-bonded C 1 -C 10 hydrocarbyl radical free of aliphatic carbon-carbon multiple bonds,

x is a non-negative number such that at least two R 1 radicals are present in each molecule, and

y is a non-negative number such that (x+y) is in the range from 1.9 to 2.2.

5. The silicone mixture of claim 1 , in which at least one organosilicon compound (C) has a composition of the average formula VII

H a R 3 b SiO (4-a-b)/2   (VII)

in which

R 3 is a monovalent, optionally halogen- or cyano-substituted, SiC-bonded C 1 -C 18 hydrocarbyl radical free of aliphatic carbon-carbon multiple bonds and

a and b are non-negative integers,

with the proviso that 0.5<(a+b)<3.0 and 0<a<2, and that at least two silicon-bonded hydrogen atoms are present per molecule.

6. The silicone mixture of claim 2 , in which at least one organosilicon compound (C) has a composition of the average formula VII

H a R 3 b SiO (4-a-b)/2   (VII)

in which

R 3 is a monovalent, optionally halogen- or cyano-substituted, SiC-bonded C 1 -C 18 hydrocarbyl radical free of aliphatic carbon-carbon multiple bonds and

a and b are non-negative integers,

with the proviso that 0.5<(a+b)<3.0 and 0<a<2, and that at least two silicon-bonded hydrogen atoms are present per molecule.

7. The silicone mixture of claim 3 , in which at least one organosilicon compound (C) has a composition of the average formula VII

H a R 3 b SiO (4-a-b)/2   (VII)

in which

R 3 is a monovalent, optionally halogen- or cyano-substituted, SiC-bonded C 1 -C 18 hydrocarbyl radical free of aliphatic carbon-carbon multiple bonds and

a and b are non-negative integers,

with the proviso that 0.5<(a+b)<3.0 and 0<a<2, and that at least two silicon-bonded hydrogen atoms are present per molecule.

8. The silicone mixture of claim 4 , in which at least one organosilicon compound (C) has a composition of the average formula VII

H a R 3 b SiO (4-a-b)/2   (VII)

in which

R 3 is a monovalent, optionally halogen- or cyano-substituted, SiC-bonded C 1 -C 18 hydrocarbyl radical free of aliphatic carbon-carbon multiple bonds and

a and b are non-negative integers,

with the proviso that 0.5<(a+b)<3.0 and 0<a<2, and that at least two silicon-bonded hydrogen atoms are present per molecule.

9. A process for producing a silicone fiber, comprising continuously extruding a silicone mixture of claim 1 through a die onto a conveyor belt and vulcanizing with a UV light source having a wavelength of 200-500 nm.

10. A process for producing a silicone fiber, comprising continuously extruding a silicone mixture of claim 2 through a die onto a conveyor belt and vulcanizing with a UV light source having a wavelength of 200-500 nm.

11. A process for producing a silicone fiber, comprising continuously extruding a silicone mixture of claim 3 through a die onto a conveyor belt and vulcanizing with a UV light source having a wavelength of 200-500 nm.

12. A process for producing a silicone fiber, comprising continuously extruding a silicone mixture of claim 4 through a die onto a conveyor belt and vulcanizing with a UV light source having a wavelength of 200-500 nm.

13. A process for producing a silicone fiber, comprising continuously extruding a silicone mixture of claim 5 through a die onto a conveyor belt and vulcanizing with a UV light source having a wavelength of 200-500 nm.

14. A process for producing a silicone fiber, comprising continuously extruding a silicone mixture of claim 6 through a die onto a conveyor belt and vulcanizing with a UV light source having a wavelength of 200-500 nm.

15. A process for producing a silicone fiber, comprising continuously extruding a silicone mixture of claim 7 through a die onto a conveyor belt and vulcanizing with a UV light source having a wavelength of 200-500 nm.

16. A process for producing a silicone fiber, comprising continuously extruding a silicone mixture of claim 8 through a die onto a conveyor belt and vulcanizing with a UV light source having a wavelength of 200-500 nm.

17. The transparent silicone mixture of claim 1 , wherein B is present in an amount of from 25 to 80 parts per 100 parts A.

18. The transparent silicone composition of claim 1 , which has a viscosity of ≧1000 Pa·s measured at 25° C.

19. A transparent silicone mixture crosslinkable under the influence of light, comprising

(A) at least one organosiloxane resin comprising units of the formulae I, II, III and IV

R 3 SiO 1/2   (I),

R 2 SiO 2/2   (II),

RSiO 3/2   (III),

SiO 4/2   (IV),

in which

R are saturated hydrocarbyl radicals optionally substituted by halogens, and having 1-40 carbon atoms, —OH, or a C 1-10 alkenyl radical with the proviso that at least 20 mol % of the units are selected from units of the general formulae III and IV,

at least 2 of the R radicals are alkenyl radicals having 1-10 carbon atoms and

at most 2% by weight of the R radicals are —OH radicals,

(B) at least one polyorganosiloxane containing at least two alkenyl groups per molecule and having a chain length of the longest chain of 200 to 10,000 siloxy units,

(C) at least one organosilicon compound containing at least two SiH functions per molecule and

(D) as one catalyst, MeCp(PtMe 3 ) activatable by light from 200 to 500 nm,

wherein the transparent silicone composition has a viscosity of ≧1000 Pa·s measured at 25° C.