Producing soft contact lenses

• US 4,347,198 A
• Filed: 09/25/1980
• Issued: 08/31/1982
• Est. Priority Date: 09/12/1977
• Status: Expired due to Term

• Current Assignee: Toray Industries Incorporated
• Original Assignee: Toray Industries Incorporated
• Inventors: Kenjo, Hideki, Ohkada, Shinzo
• Primary Examiner(s): Lowe, James B.
• Application Number:
  US06/190,820
• Time in Patent Office: 705 Days
• Field of Search: 264/1.1, 264/2.2, 264/2.3, 264/2.6, 425/808
• US Class Current: 264/2.3
• 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: G02B 1/043 Contact lenses
• CPC Class Codes: Y10S 425/808 Lens mold

Abstract

A soft contact lens is provided by: pouring an excess amount of an original solution for producing a soft contact lens into a concave mold; placing a convex mold on said concave mold and overflowing the excess of said original solution to thereby uniformly fill said original solution in a space between said concave mold and said convex mold; gelling said original solution between the two molds to form therebetween a lens having a tensile strength of at least about 0.1 kgf/cm² ; immersing said lens and said two molds in a liquid to peel said lens from said molds; and extracting the thus-peeled lens via an extraction treatment with water. The "original solution" contains:

a component A selected from the group consisting of monomers and hydrophillic polymers wherein the monomers yield hydrophillic component when polymerized;

a compound B selected from the group consisting of monomers and hydrophobic polymers wherein the monomers yield hydrophobic component when polymerized; and

a solvent C

the weight ratio of A:B being from about 85:15 to about 55:45 and solvent C being about 5 to 95% by weight.

Claims

1. A process for producing a soft contact lens comprising:

pouring an excess amount of an original solution for producing a soft contact lens into a concave mold which is placed in a vessel,

said original solution comprising a component (A) selected from the group consisting of hydrophilic polymers and monomers which yield a hydrophilic component when polymerized, a component (B) selected from the group consisting of hydrophobic polymers and monomers which yield a hydrophobic component when polymerized, and a solvent (C),

the weight ratio of (A);

(B) being from about 85;

15 to about 55;

45 and solvent (C) being about 50 to 95% by weight of the total original solution;

placing a convex mold on said concave mold and overflowing the excess of said original solution, the vapor pressure of the lowest boiling component in said original solution inside said vessel being at least about 20% of the saturated partial pressure exhibited by said original solution;

gelling said original solution between the two molds to form therebetween a lens having a tensile strength of at least about 0.1 kgf/cm² ;

immersing said lens and said two molds in a liquid to peel said lens from said molds; and

extracting the thus-peeled lens by an extraction treatment with water.

2. A process of claim 1, wherein said original solution has a coefficient of gellation contraction at the same temperature and the same pressure of less than about 5% by volume.

3. A process of claim 2, wherein said original solution contains N-vinyl lactam and a lower alkyl ester of acrylic acid or methacrylic acid.

4. A process of claim 2, wherein said original solution contains a polymer of a lower alkyl ester of methacrylic acid having an ethylenic double bond in the side chain and N-vinyl lactam.

5. A process of claim 1 wherein said concave mold and said convex mold are made of glass.

6. A process of claim 5, wherein peeling of said lens from said molds is carried out in dimethyl sulfoxide containing water.

7. A process of claim 1, wherein said convex mold has a non-interference surface.

8. The process for producing a soft contact lens of claim 1, wherein the gelling is performed by heating said original solution between said two molds while squeezing the two molds with an outer force of about 10-100 kgf/cm².

9. The process of claim 1, wherein the solvent (C) is about 70 to 80% by weight of the total original solution.

10. A process for producing a soft contact lens comprising:

pouring an excess amount of an original solution for producing a soft contact lens into a concave glass mold which is placed in a vessel,

said original solution comprising a component (A) selected from the group consisting of hydrophilic polymers and monomers which yield a hydrophilic component when polymerized, a component (B) selected from the group consisting of hydrophobic polymers and monomers which yield a hydrophobic component when polymerized, and a solvent (C),

the weight ratio of (A);

(B) being from about 85;

15 to about 55;

45 and solvent (C) being about 50 to 95% by weight of the total original solution;

placing a convex mold onto said concave glass mold and overflowing the excess of said original solution, the vapor pressure of the lowest boiling component in said original solution inside said vessel being at least about 20% of the saturated partial pressure exhibited by said original solution;

gelling by heating said original solution between said two molds to form a lens having a tensile strength of at least about 0.1 kgf/cm² in said two molds;

immersing said lens and said molds in a liquid to peel said lens from said molds; and

extracting the thus-peeled lens by an extraction treatment with water.

11. The process of claim 10, wherein the solvent (C) is about 70 to 80% by weight of the total original solution.