Contact lenses with improved wearing comfort

1. A contact lens which is obtained by crosslinking in a mold an aqueous formulation comprising a crosslinkable polyvinyl alcohol prepolymer, a first non-reactive polyvinyl alcohol having a lower molecular weight M n of from 25000 to 50000, and a second non-reactive polyvinyl alcohol having a higher molecular weight M n of from above 50000 to 100000, wherein the crosslinkable polyvinyl alcohol prepolymer comprises a polyvinylacetate backbone and photocrosslinkable or thermally crosslinkable groups, wherein the first and second non-reactive polyvinyl alcohols are devoid of polymerizable groups, wherein the difference in number-average molecular weight between the first and second non-reactive polyvinyl alcohols is at least 10000, wherein the first and second non-reactive polyvinyl alcohols are present in the aqueous formulation in an amount of from 0.25 to 3% by weight, based on the entire weight of the aqueous formulation, wherein the weight proportion of the lower molecular weight M n non-reactive polyvinyl alcohol and higher molecular weight M n non-reactive polyvinyl alcohol in the aqueous formulation is from 1:1 to 5:1, wherein the contact lens is characterized by having an improved end-of-day wearing comfort relative to contact lenses manufactured according to an identical process without the addition of the amount of the first and second non-reactive polyvinyl alcohols in the aqueous formulation for making the contact lenses.

2. The contact lens according to claim 1 , wherein the crosslinkable polyvinyl alcohol prepolymer is a derivative of a polyvinyl alcohol having an average molecular weight M n of at least 10000, wherein, based on the number of hydroxy groups of the polyvinyl alcohol, from approximately 0.5 to approximately 80% of units of the crosslinkable polyvinyl alcohol prepolymer is represented by formula (1)

wherein R is C 1 -C 8 -alkylene, R 1 is hydrogen or C 1 -C 7 -alkyl and R 2 is an ethylenically unsaturated, electron-attracting, copolymerizable radical having up to 25 carbon atoms.

3. The contact lens of claim 2 , which is a hydrogel contact lens.

4. The contact lens of claim 3 , wherein R 2 is a radical of formula (2)

—CO—NH—(R 4 —NH—CO—O) q —R 5 —O—CO—R 3   (2),

wherein q is zero or one and R 4 and R 5 are each independently C 2 -C 8 -alkylene, C 8 -C 12 -arylene, a saturated divalent C 6 -C 10 -cycloaliphatic group, C 7 -C 14 -arylenealkylene or C 7 -C 14 -alkylenearylene or C 13 -C 16 -arylenealkylenearylene, and R 3 is C 2 -C 8 -alkenyl.

5. The contact lens of claim 4 , wherein the weight proportion of the lower molecular weight M n non-reactive polyvinyl alcohol and the higher molecular weight M n non-reactive polyvinyl alcohol in the aqueous formulation is from 1:1 to 4:1.

6. The contact lens of claim 5 , wherein the crosslinkable polyvinyl alcohol prepolymer has a number average molecular weight M n of from 12000 to 25000.

7. The contact lens of claim 6 , wherein the aqueous formulation comprises in addition a polyethylene-polypropylene block copolymer.

8. The contact lens of claim 4 , wherein the crosslinkable polyvinyl alcohol prepolymer has a number average molecular weight M n of from 12000 to 25000, wherein the first non-reactive polyvinyl alcohol has a lower average molecular weight M n of from 30000 to 50000, wherein the second non-reactive polyvinyl alcohol has a higher average molecular weight M n of from above 50000 to 100000.

9. The contact lens of claim 3 , wherein R is C 1 -C 4 -alkylene, R 1 is hydrogen or C 1 -C 4 -alkyl, and R 2 is a radical R 3 -CO—, in which R 3 is C 2 -C 4 -alkenyl.

10. The contact lens of claim 9 , wherein the weight proportion of the lower molecular weight M n non-reactive polyvinyl alcohol and the higher molecular weight M n non-reactive polyvinyl alcohol in the aqueous formulation is from 1:1 to 4:1.

11. The contact lens of claim 9 , wherein the crosslinkable polyvinyl alcohol prepolymer has a number average molecular weight M n of from 12000 to 25000, wherein the first non-reactive polyvinyl alcohol has a lower average molecular weight M n of from 30000 to 50000, wherein the second non-reactive polyvinyl alcohol has a higher average molecular weight M n of from above 50000 to 100000.

12. The contact lens of claim 3 , wherein the weight proportion of the lower molecular weight M n non-reactive polyvinyl alcohol and the higher molecular weight M n non-reactive polyvinyl alcohol in the aqueous formulation is from 1:1 to 4:1.

13. The contact lens of claim 12 , wherein the crosslinkable polyvinyl alcohol prepolymer has a number average molecular weight M n of from 12000 to 25000.

14. The contact lens of claim 3 , wherein the aqueous formulation comprises in addition a polyethylene-polypropylene block copolymer.

15. The contact lens of claim 3 , wherein the crosslinkable polyvinyl alcohol prepolymer has a number average molecular weight M n of from 12000 to 25000, wherein the first non-reactive polyvinyl alcohol has a lower average molecular weight M n of from 30000 to 50000 and wherein the second non-reactive polyvinyl alcohol has a higher average molecular weight M n of from above 50000 to 100000.

16. The contact lens of claim 15 , wherein the weight proportion of the lower molecular weight M n non-reactive polyvinyl alcohol and the higher molecular weight M n non-reactive polyvinyl alcohol in the aqueous formulation is from 1:1 to 4:1.

17. The contact lens of claim 16 , wherein the aqueous formulation of the crosslinkable polyvinyl alcohol prepolymer comprises in addition a polyethylene-polypropylene block copolymer.