Method of Treating a Lens Forming Surface of at Least One Mold Half of a Mold for Molding Ophthalmic Lenses

• US 20130147072A1
• Filed: 11/26/2012
• Published: 06/13/2013
• Est. Priority Date: 11/29/2011
• Status: Active Grant

• Current Assignee: Alcon Incorporated
• Original Assignee: Novartis Ag
• Inventors: Bothe, Harald, Matsuzawa, Yasuo
• Granted Patent: US 9,358,735 B2
• Time in Patent Office: Days
• US Class Current: 264/1.36
• CPC Class Codes: B29C 2033/725 cleaning by plasma treatment
• CPC Class Codes: B29C 33/72 Cleaning extruder parts B29C48/27; in general B08B7/00
• CPC Class Codes: B29D 11/00009 Production of simple or compound lenses
• CPC Class Codes: B29D 11/00038 Production of contact lenses
• CPC Class Codes: B29D 11/00125 Auxiliary operations, e.g. removing oxygen from the mould, conveying moulds from a storage to the production line in an inert atmosphere
• CPC Class Codes: B29D 11/0048 Moulds for lenses moulds for plastic articles in general B29C33/00

Abstract

A method of treating of a lens forming surface (2) of at least one mold half (1) of a mold for molding an ophthalmic lens, in particular of the lens forming surface of a glass mold half for molding a contact lens, especially a soft contact lens, includes the steps of:

• • providing a plasma (10) under atmospheric pressure, and
  • exposing the lens forming surface (2) to the plasma (10) under atmospheric pressure thereby hydrophilizing the lens forming surface (2) without depositing any material on the lens forming surface (2).

Claims

1. Method of treating of a lens forming surface (2) of at least one mold half (1) of a mold for molding an ophthalmic lens, in particular of the lens forming surface of a glass mold half for molding a contact lens, especially a soft contact lens, the method including the steps of:

providing a plasma (10) under atmospheric pressure, and

exposing the lens forming surface (2) to the plasma (10) under atmospheric pressure thereby hydrophilizing the lens forming surface (2) without depositing any material on the lens forming surface (2).

2. Method according to claim 1, wherein the mold comprises a male mold half and a female mold half, and wherein the lens forming surfaces of both the male mold half and the female mold half are exposed to the plasma.

3. Method according to claim 2, wherein the lens forming surfaces of the male mold half and of the female mold half are exposed to the plasma for different periods of time.

4. Method according to claim 1, wherein the mold comprises a male mold half and a female mold half, and wherein the lens forming surface of only one of the male and female mold halves is exposed to the plasma.

5. Method according to claim 4, wherein the lens forming surface of only the female mold half is exposed to the plasma.

6. Method according to any one of the preceding claims, wherein the plasma is a plasma of a gas selected from the group consisting of argon, helium, nitrogen, oxygen, tetrafluoroethane, air, or a mixture of argon and oxygen, argon and nitrogen, argon and air, argon and tetrafluoroethane, helium and oxygen, helium and nitrogen, helium and air, helium and tetrafluoroethane, nitrogen and oxygen.

7. Method according to any one of the preceding claims, wherein the plasma is a plasma of argon or a plasma of a mixture of argon and oxygen.

8. Method according to any one of the preceding claims, wherein the lens forming surface is exposed to the plasma such that the water contact angle of the treated lens forming surface is smaller than 40°

, preferably smaller than 20°

, and more preferably smaller than 10°

.

9. Method according to any one of the preceding claims, wherein the lens forming surface is exposed to the plasma for a time period not exceeding 20 seconds, preferably for a time period in the range of 5 to 20 seconds, and more preferably for a time period in the range of 10 to 20 seconds.

10. Method according to any one of the preceding claims, wherein the plasma (10) is generated with the aid of a plasma torch comprising a plasma gun (6) and a tubular plasma concentrator (4), the plasma concentrator (4) sealingly surrounding the space between the plasma gun (6) and the lens forming surface (2) of the mold or mold half.

11. Method according to claim 9, wherein the mold half exposed to plasma is a male mold half (1) which is provided with an annular mask (3) made from metal, the annular mask (3) being arranged to surround the lens forming surface (2) of the male mold half (1), and wherein the annular mask (3) is shielded from exposure to the plasma by the plasma concentrator (4, 5).

12. Method of molding an ophthalmic lens, in particular a contact lens, especially a soft contact lens, the method comprising the steps of providing a mold comprising a male mold half and a female mold half, each of the male and female mold halves having a lens forming surface, introducing a lens forming material into the male mold half or the female mold half, assembling the male and female mold halves, exposing the lens forming material arranged between the lens forming surfaces of the male and female mold halves to polymerizing and/or crosslinking energy to form the ophthalmic lens, disassembling the male and female mold halves to open the mold, and removing the ophthalmic lens from the male mold half or from the female mold half,

wherein the lens forming surface of either both the male and female mold halves or of only one of the male and female mold halves is treated by a method according to any one of the preceding claims prior to introducing the lens forming material into the male mold half or the female mold half.

13. Method according to claim 11, wherein the mold halves are reusable and are reused to mold a plurality of ophthalmic lenses, and wherein the lens forming surface(s) of one of the mold halves or of both mold halves is exposed to the plasma again after molding a predetermined number of ophthalmic lenses.

14. Method according to claim 11, wherein the mold halves are reusable mold halves which are reused to mold a plurality of ophthalmic lenses, and wherein the lens forming surface(s) of one of the mold halves or of both mold halves is exposed to the plasma prior to molding of each ophthalmic lens.

15. Method according to any one of claims 12 to 14, wherein said ophthalmic lens is a silicon hydrogel ophthalmic lens, in particular a silicon hydrogel soft contact lens.