Method for removing lens forming material deposited on a lens forming surface

Patent metadata

Field	Value
Publication number	US-11759980-B2
Application number	US-202017083559-A
Country	US
Kind code	B2
Filing date	Oct 29, 2020
Priority date	Oct 31, 2019
Publication date	Sep 19, 2023
Grant date	Sep 19, 2023

Abstract

A method of removing a lens forming material deposited on a lens forming surface ( 1 ) of a reusable glass mold for forming ophthalmic lenses, in particular contact lenses or intraocular lenses, comprises the steps of providing a plasma ( 2 ), exposing the lens forming surface ( 1 ) of the reusable glass mold to the plasma ( 2 ) for removing the lens forming material deposited on the lens forming surface ( 1 ). The plasma ( 2 ) is generated under atmospheric pressure and potential-free, or is generated under reduced pressure.

First claim

The invention claimed is:

1. Method of removing lens forming material deposited on a lens forming surface ( 1 ) of a reusable glass mold for forming contact lenses, the method comprising the steps of:
a) removing a lens from the reusable glass mold,
b) providing a plasma ( 2 ),
c) exposing the lens forming surface ( 1 ) of the reusable glass mold with the lens forming material deposited thereon after step a) to the plasma ( 2 ) for removing the lens forming material deposited on the lens forming surface ( 1 ), and
d) aspirating an off-gas generated by exposing the deposited lens forming material to be removed to the plasma ( 2 ), wherein lens forming material is a silicone hydrogel,
wherein the plasma ( 2 ) is generated under atmospheric pressure and potential-free,
wherein the generating the plasma ( 2 ) under atmospheric pressure comprising generating the plasma ( 2 ) with a plasma jet ( 4 ) using air as a process gas, and wherein the plasma is generated with the aid of a plasma torch ( 6 ) comprising the plasma jet ( 4 ), a tubular plasma jacket ( 7 ) and an aspirator connection ( 8 ), the plasma jacket ( 7 ) surrounding the space between the plasma jet ( 4 ) and the lens forming surface ( 1 ) of the mold, and wherein the method further comprises applying vacuum to the aspirator connection ( 8 ), thereby allowing aspiration of the off-gas.

2. Method according to claim 1 , wherein the lens forming surface ( 1 ) exposed to the plasma ( 2 ) is provided with an annular mask ( 3 ) made from chromium, the annular mask being arranged to surround the lens forming surface.

3. Method according to claim 1 , wherein the plasma ( 2 ) is generated with a plasma generator at an output power of in the range of 150 W to 500 W, and wherein the air is injected into the plasma jet at an input pressure in the range of 5 bars to 8 bars.

4. Method according to claim 3 , wherein during injection into the plasma jet the air has a flow rate in the range of 10001/h to 2000 l/h.

5. Method according to claim 1 , wherein the plasma jet ( 4 ) has an outlet orifice ( 5 ) at the tip of the plasma jet ( 4 ), and wherein exposing the lens forming surface ( 1 ) to the plasma ( 2 ) comprises arranging an apex of the lens forming surface ( 1 ) at a distance in the range of 3 mm to 7 mm from the outlet orifice ( 5 ) of the tip of the plasma jet ( 4 ).

Assignees

• Alcon Inc

Inventors

• Kastl Stefan
• Paulekuhn Steffen
• Pirl Stephan
• Cocora Gabriela

Classifications

• B29D11/00038 Primary

  Production of contact lenses · CPC title

• B29C33/72 Primary

  Cleaning {(extruder parts B29C48/27; in general B08B7/00)} · CPC title

• B29D11/00519

  Reusable moulds · CPC title

• B29D11/00125

  Auxiliary operations, e.g. removing oxygen from the mould, conveying moulds from a storage to the production line in an inert atmosphere · CPC title

• B29C2033/725

  cleaning by plasma treatment · CPC title