Methods and apparatus for producing contact lenses

Patent metadata

Field	Value
Publication number	US-12508787-B2
Application number	US-202418641470-A
Country	US
Kind code	B2
Filing date	Apr 22, 2024
Priority date	Apr 28, 2023
Publication date	Dec 30, 2025
Grant date	Dec 30, 2025

Abstract

The present invention concerns methods and an apparatus for producing contact lenses, such as silicone hydrogel contact lenses, and further relates to methods and an apparatus for producing silicone hydrogel contact lens mold assemblies, methods and apparatus for producing silicone hydrogel contact lenses using such mold assemblies, and silicone hydrogel contact lenses and lens member bodies produced using such methods and apparatus.

First claim

The invention claimed is:

1 . A method of producing a silicone hydrogel contact lens mold assembly, the method comprising;
placing one of a male mold member and a female mold member on the other of a male mold member and a female mold member to form a contact lens mold assembly comprising a contact lens shaped cavity defined between the male mold member and the female mold member, said cavity containing a polymerizable silicone hydrogel contact lens precursor composition; and coupling the male mold member and the female mold member together by inserting one or more heated elongate elements into the male and female mold members thereby causing a portion of the male and/or female mold members to become melted or softened, and then withdrawing said one or more heated elongate elements from the male and female mold members, wherein said melted or softened material then cools to form a weld between the male and female mold members; and wherein throughout a first time period beginning when the first of said one or more heated elongate elements is inserted into the male and female mold members and continuing until at least 3 seconds after the last of said one or more heated elongate elements is withdrawn from the male and female mold members, the male and female mold members are pressed together by applying a force in the range of from 20 N to 100 N to the male and female mold members.

2 . The method of producing a silicone hydrogel contact lens mold assembly according to claim 1 , wherein said male mold member and said female mold member comprise polypropylene, and optionally, wherein said polypropylene has a Melt Flow Rate of 19 dg/min at 230° C. and 2.16 kg.

3 . The method of producing a silicone hydrogel contact lens mold assembly according to claim 2 , wherein said polypropylene has a tensile modulus of 1800 MPa (measured at 1 mm/min) and/or a flexural modulus of 1900 MPa (measured at 1%/minute).

4 . The method of producing a silicone hydrogel contact lens mold assembly according to claim 1 , wherein said first time period continues until at least 5 seconds after the last of said one or more heated elongate elements is withdrawn from the male and female mold members.

5 . The method of producing a silicone hydrogel contact lens mold assembly according to claim 1 , wherein said first time period continues for from 3 to 7 seconds after the last of said one or more heated elongate elements is withdrawn from the male and female mold members.

6 . The method of producing a silicone hydrogel contact lens mold assembly according to claim 1 , wherein the female and male mold members are pressed together by applying a force in the range of from 50 N to 80 N throughout said first time period.

7 . The method of producing a silicone hydrogel contact lens mold assembly according to claim 1 , wherein said step of placing one of a male mold member and a female mold member on the other of a male mold member and a female mold member comprises dropping one mold member onto the other mold member, and optionally wherein the male mold member is dropped onto the female mold member.

8 . The method of producing a silicone hydrogel contact lens mold assembly according to claim 7 , wherein the mold member is dropped from a height of from 0.5 mm to 5 mm.

9 . The method of producing a silicone hydrogel contact lens mold assembly according to claim 1 , wherein a second time period of at least 3 seconds elapses between placing the male mold member on the female mold member and the male and female mold members being pressed together.

10 . The method of producing a silicone hydrogel contact lens mold assembly according to claim 1 , wherein the male mold member and female mold member form an interference fit when pressed together.

11 . The method of producing a silicone hydrogel contact lens mold assembly according to claim 1 , wherein the lens shaped cavity defined between the male mold member and the female mold member has a thickness of at least 10 μm when measured at a distance of 50 μm from the peripheral edge of the cavity.

12 . The method of producing a silicone hydrogel contact lens mold assembly according to claim 1 , wherein the one or more heated elongate elements pass through the male and female mold members.

13 . The method of producing a silicone hydrogel contact lens mold assembly according to claim 1 , wherein the volume of lens precursor composition in the cavity is from 40 μl to 60 μl.

14 . A method of making a silicone hydrogel contact lens member, comprising:
forming a silicone hydrogel contact lens mold assembly according to the method of claim 1 ; and optionally, exposing the mold assembly to radiation to polymerize the polymerizable silicone hydrogel contact lens precursor composition to produce a contact lens body; separating the male mold member from the female mold member, leaving the contact lens body in contact with the male and/or female mold member; removing the contact lens body from said male and/or female mold member; and/or extracting extractable materials from the contact lens body and/or hydrating the contact lens body to form a silicon hydrogel contact lens member.

15 . A system for the production of a silicone hydrogel contact lens mold assembly, the mold assembly comprising a contact lens shaped cavity defined between a male mold member and a female mold member, the system comprising:
a clamp arranged to compress the mold assembly; one or more elongate elements, said one or more elongate elements being mounted for movement relative to the clamp to pass a tip of each elongate element through the male and female mold members while they are being compressed by the clamp, and a control system configured to control operation of the clamp and the one or more elongate elements such that throughout a first time period beginning when the first of said one or more elongate elements is inserted into the male and female mold members and continuing until at least 3 seconds after the last of said one or more elongate elements are withdrawn from the male and female mold members, the clamp exerts a force in the range of from 20 N to 100 N on the male and female mold members.

16 . The system according to claim 15 , further comprising a support configured to retain a first mold member in a substantially fixed location, said first mold member being one of the male mold member and the female mold member, and a second mold member being the other of the male mold member and female mold member; and
the clamp comprises a clamp foot arranged to compress the first and second mold members between the clamp foot and the support when the first mold member is retained in the support and the second mold member is placed on the first mold member to define the lens shaped cavity therebetween; and the control system is configured to control operation of the clamp such that throughout the first time period the clamp foot exerts a force in the range of from 20 N to 100 N on the second mold member.

17 . The system according to claim 15 , further comprising one or more sensors configured to detect the position of the elongate heated elements and/or one or more sensors configured to determine the force exerted on the male and female mold members by the clamp, and wherein the control system is configured to control operation of the clamp and/or elongate heated elements in dependence on a signal received from said one or more sensors.

18 . The system according to claim 16 , further comprising a second support retaining one of the male or female mold member in

Assignees

• Coopervision Int Ltd

Inventors

• Oag Robert
• Evans Edward James Harley
• Frith Robin

Classifications

• B29D11/0048 Primary

  Moulds for lenses (moulds for plastic articles in general B29C33/00) · CPC title

• B29D11/00173

  Conveying moulds · CPC title

• B29D11/00038

  Production of contact lenses · CPC title

• B29C66/949

  characterised by specific time values or ranges · CPC title

• B29C66/9241

  by controlling or regulating the pressure, the force or the mechanical power · CPC title