High refractive index polysiloxanes and their preparation
View Patent ↗A polysiloxane having a refractive index of about 1.56 measured at light wavelength 633 nm, characterized in that the polysiloxane includes siloxane T units of the formula where A represents an alkylene group having 1 to 4 carbon atoms: n=0 or 1; m is at least 1; and Ar is an aryl group substituted by at least one iodine, bromine or chlorine atom, or is a polynuclear aromatic group. The invention includes chlorosilanes having the formula (Ar) m-(A)nSiCl3, useful in forming high refractive index polysiloxanes.
1. A polysiloxane having a refractive index of at least 1.581 measured at light wavelength 633 nm, which polysiloxane includes siloxane T units of the formula:
where A represents an alkylene group having 1 to 4 carbon atoms; n=0 or 1; m is at least 1; and Ar is a polynuclear aromatic group substituted by at least one iodine, bromine or chlorine atom,
wherein at least 20% of the siloxane units of the resin are of formula (I), and
wherein at least 5% of the siloxane units of the resin are SiO4/2 units, provided said polysiloxane is substantially free of M and D units.
2. A polysiloxane according to claim 1 in which at least 10% of the siloxane units of the resin are SiO4/2 units.
3. A polysiloxane according to claim 1 in which the polysiloxane also contains curable groups selected from the group consisting of alkenyl groups, Si—H groups, epoxyalkyl groups, aminoalkyl groups, and Si—OH groups.
4. A process for producing a high refractive index article comprising forming a high refractive index polysiloxane as claimed in claim 1 into an article and curing the article.
5. A polysiloxane according to claim 1 in which n is 1, A has more than 1 carbon atom, m is at least 2.
6. A polysiloxane according to claim 1 in which n is 0 for at least 50% of the siloxane units of formula (I) and n is 1 for up to 50% of the siloxane units of formula (I) in the resin.
7. A process for forming a high refractive index layer on a substrate comprising coating the substrate with a high refractive index polysiloxane and curing the coating, the high refractive index polysiloxane having a refractive index of at least 1.58 1 measured at light wavelength 633 nm, and which high refractive index polysiloxane includes siloxane T units of the formula:
where A represents an alkylene group having 1 to 4 carbon atoms; n=0 or 1; m is at least 1; and Ar is selected from the group consisting of (i) an aryl group substituted by at least one halogen selected from the group consisting of iodine, bromine and chlorine atom, and (ii) a polynuclear aromatic group,
wherein at least 20% of the siloxane units of the resin are of formula (I), and
wherein at least 5% of the siloxane units of the resin are SiO4/2 units,
provided the polysiloxane is substantially free from M and D units.
8. A process according to claim 7 in which Ar is an optionally substituted naphthyl, anthracenyl, phenanthrenyl or pyrenyl group.
9. A process according to claim 7 in which Ar is a polynuclear aromatic group substituted by at least one iodine, bromine or chlorine atom.
10. A process according to claim 7 in which Ar is a phenyl group substituted by at least one iodine atom.
11. A process according to claim 7 in which Ar is an optionally substituted polynuclear group having non-fused aromatic rings.
12. A process according to claim 7 in which at least 10% of the siloxane units of the resin are SiO04/2 units.
13. A process according to claim 7 in which the polysiloxane also contains curable groups selected from the group consisting of alkenyl groups, Si—H groups, epoxyalkyl groups, aminoalkyl groups, and Si—OH groups.
14. A process according to claim 7 in which n is 1, A has more than 1 carbon atom, m is at least 2.
15. A process according to claim 7 in which n is 0 for at least 50% of the siloxane units of formula (I) and n is 1 for up to 50% of the siloxane units of formula (I) in the resin.
16. A polysiloxane having a refractive index of at least 1.581 measured at light wavelength 633 nm, which polysiloxane includes siloxane T units of the formula:
where A represents an alkylene group having 1 to 4 carbon atoms; n=0 or 1; m is at least 1; and Ar is a phenyl group substituted by at least one iodine atom,
wherein at least 20% of the siloxane units of the resin are of formula (I), and
wherein at least 5% of the siloxane units of the resin are SiO4/2 units,
provided said polysiloxane is substantially free of M and D units.
17. A polysiloxane according to claim 16 in which at least 10% of the siloxane units of the resin are SiO4/2 units.
18. A polysiloxane according to claim 16 in which the polysiloxane also contains curable groups selected from the group consisting of alkenyl groups, Si—H groups, epoxyalkyl groups, aminoalkyl groups, and Si—OH groups.
19. A polysiloxane according to claim 16 in which n is 1, A has more than 1 carbon atom, m is at least 2.
20. A polysiloxane according to claim 16 in which n is 0 for at least 50% of the siloxane units of formula (I) and n is 1 for up to 50% of the siloxane units of formula (I) in the resin.
21. A process for producing a high refractive index article comprising forming a high refractive index polysiloxane as claimed in claim 16 into an article and curing the article.
22. A substrate including a coating formed thereon from a cured high refractive index polysiloxane, said high refractive index polysiloxane having a refractive index of at least 1.581 measured at light wavelength 633 nm, and which high refractive index polysiloxane includes siloxane T units of the formula:
where A represents an alkylene group having 1 to 4 carbon atoms; n=0 or 1; m is at least 1; and Ar is selected from the group consisting of (i) an aryl group substituted by at least one halogen selected from the group consisting of iodine, bromine and chlorine atom, and (ii) a polynuclear aromatic group,
wherein at least 20% of the siloxane units of the resin are of formula (I), and
wherein at least 5% of the siloxane units of the resin are SiO4/2 units,
provided said polysiloxane is substantially free of M and D units.
23. A substrate including a coating formed thereon according to claim 22 in which at least 10% of the siloxane units of the resin are SiO4/2 units.
24. A substrate including a coating formed thereon according to claim 22 in which Ar is an optionally substituted naphthyl, anthracenyl, phenanthrenyl or pyrenyl group.
25. A substrate including a coating formed thereon according to claim 22 in which Ar is a polynuclear aromatic group substituted by at least one iodine, bromine or chlorine atom.
26. A substrate including a coating formed thereon according to claim 22 in which Ar is a phenyl group substituted by at least one iodine atom.
27. A substrate including a coating formed thereon according to claim 22 in which the polysiloxane also contains curable groups selected from the group consisting of alkenyl groups, Si—H groups, epoxyalkyl groups, aminoalkyl groups, and Si—OH groups.
28. A substrate including a coating formed thereon according to claim 22 in which Ar is an optionally substituted polynuclear group having non-fused aromatic rings.
29. A substrate including a coating formed thereon according to claim 22 in which n is 1, A has more than 1 carbon atom, m is at least 2.
30. A substrate including a coating formed thereon according to claim 22 in which n is 0 for at least 50% of the siloxane units of formula (I) and n is 1 for up to 50% of the siloxane units of formula (I) in the resin.