Process for Manufacturing a Polarized Poly(thio)urethane Optical Lens

Abstract

The invention relates to a process for manufacturing a polarized poly(thio)urethane-based optical article comprising the steps of disposing a polarizing film or wafer in a molding cavity of a two part mold assembly; pouring a polymerizable composition comprising at least one polyiso(thio)cyanate monomer and at least one polyol and/or polythiol; or a mixture of at least one liquid NCO and/or NCS terminated poly(thio)urethane prepolymer and at least one liquid OH and/or SH terminated poly(thio)urethane prepolymer; with the proviso that the polymerizable composition has a ratio of NH2 functionalities to the NCO or NCS functionalities of less than 0.9; polymerizing the composition under such conditions that a hard gel is obtained in less than 30 minutes; completing the polymerization; and opening the two part mold so as to recover the bubble free optical article.

Description

DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic representation of a two part mold assembly which can be used for molding polarized ophthalmic lenses according to the invention, and

FIG. 2 is a Fourier Transform Infra Red Spectrum (FTIR) of the polarizing wafer used in the example 1 at different times of the hydrolysis treatment thereof (with NaOH).

FIG. 3 is a Fourier Transform Infra Red Spectrum (FTIR) of the polarizing wafer used in example 2 showing also the peak corresponding to OH groups after NaOH hydrolysis and drying of the polarizing wafer.

Claims

1. A process for manufacturing a poly(thio)urethane-based optical article comprising the steps of: disposing a polarizing film or wafer in a molding cavity of a two part mold assembly;pouring a polymerizable composition comprising: a) at least one polyiso(thio)cyanate monomer and at least one polyol and/or polythiol; orb) a mixture of at least one liquid NCO and/or NCS terminated poly(thio)urethane prepolymer and at least one liquid OH and/or SH terminated poly(thio)urethane prepolymer;c) with the proviso that the polymerizable composition has a ratio of NH2 functionalities to the NCO or NCS functionalities of less than 0.9;polymerizing the composition under such conditions that a hard gel is obtained in less than 30 minutes,completing the polymerization,opening the two part mold and recovering the bubble free optical article.

2. The process of claim 1, wherein the polymerizable composition is free of NH2 functionalities.

3. The process of claim 1, wherein the hard gel is obtained in less than 20 minutes.

4. The process of claim 1, wherein the hard gel is obtained in less than 10 minutes.

5. The process of claim 1, wherein the polarizing film or wafer has a surface having a static contact angle with water ranging from 20° to 75°.

6. The process of claim 5, wherein the polarizing film or wafer has a surface having a static contact angle with water ranging from 25° to 35°.

7. The process of claim 1, wherein the polymerizable composition further comprises an anionic polymerization catalyst or catalyst system.

8. The process of claim 7, wherein the anionic polymerization catalyst or catalyst system comprises at least one salt selected form transition metals and ammonium salts of acids, these salts fulfilling the condition 0.5≦pKa≦14.

9. The process of claim 8, wherein the salts have formula: MmP+Yn−wherein,Mp+ is a cation selected from the group consisting of alkaline metals, alkaline earth metals, transitions metals and ammonium groups of formula NR+4 in which R is an alkyl radical,Y− is an anion such that the corresponding acid YH has a pKa fulfilling the condition 0.5≦pKa≦14,p is the valency of the cation, andn=m×p.

10. The process of claim 9, wherein the cation of the salts are selected from the group consisting of Li+, Na+, K+, Rb+, Mg2+, Ca2+, Ba2+ and Al3+.

11. The process of claim 9, wherein the NR4+ groups are those in which R is a C1-C8 alkyl radical.

12. The process of claim 9, wherein the anion Y− is selected from the group consisting of thiocyanate, carboxylate, thiocarboxylate, acetylacetonate, diketone, acetoacetic ester, malonic ester, cyanoacetic ester, ketonitrile and anion of formula RS− wherein R is a substituted or non-substituted alkyl group or phenyl group.

13. The process of claim 9, wherein the anion Y− is SCN−, acetylacetonate, acetate, thioacetate, formate or benzoate.

14. The process of claim 9, wherein the salt is KSCN.

15. The process of claim 8, wherein the catalyst system further comprises at least one electro-donor compound.

16. The process of claim 15, wherein the electro-donor compound is selected from the group consisting of acetonitrile compounds, amide compounds, sulfones, sulfoxides, trialkylphosphites, nitro compounds, ethyleneglycol ethers, crown ethers and kryptates

17. The process of claim 15, wherein the electro-donor compound is selected from 18-crown-6, 18-crown-7,15-crown-5 and 15-crown-6.

18. The process of claim 8, further comprising a solvent of the catalyst or catalyst system.

19. The process of claim 1, wherein the polymerizable composition comprises a mixture of polyisocyanate[s]monomer[s] and polythiol[s]monomer[s].

20. The process of claim 1, wherein the polymerizable composition comprises a mixture of at least two polythiourethane prepolymers, one of the prepolymer being a NCO terminated prepolymer and the other being a SH terminated prepolymer.

21. The process of claim 1, wherein the polarizing wafer is a laminated wafer consisting of a PVOH (polyvinyl alcohol) polarizing layer supported on both sides with CAB layers.

22. The process of claim 1, wherein the polarizing film or wafer is previously hydrolyzed, preferably by immersion in a NaOH or HCl aqueous solution.

23. The process of claim 22, wherein immersion is effected at a temperature ranging for room temperature to 50° C.

24. The process of claim 22, wherein the polarizing film or wafer immersion is effected in 5% NaOH aqueous solution at a temperature of about 40° C.

25. The process of claim 24, wherein immersion lasts for about 30 minutes.