Pad transfer printing method for making colored contact lenses

Patent metadata

Field	Value
Publication number	US-11840035-B2
Application number	US-202318165653-A
Country	US
Kind code	B2
Filing date	Feb 7, 2023
Priority date	May 28, 2019
Publication date	Dec 12, 2023
Grant date	Dec 12, 2023

Abstract

The invention relates to a pad printing instrument comprising an ink supply system capable of control the temperature, viscosity and colorant concentration of an ink in an ink cup. Such controls are achieved by continuously adding and mixing a cold ink having a composition identical to the ink in the ink cup but having a lower temperature. The continuous addition of a small amount of a cold ink into the ink cup could compensate heat generated by the friction between the ink cup and a cliché and could minimize the evaporation of a diluent in the ink and change in the concentration of colorants in the ink and ink viscosity. The invention also relates to use of a pad printing instrument comprising an ink supply system of the invention for producing colored hydrogel or silicone hydrogel contact lenses.

First claim

What is claimed is:

1. A method for producing colored contact lenses, comprising the steps of:
(1) printing a colored image with an ink on a surface of a preformed contact lens by using a pad printing instrument that comprises a silicone pad, a printing plate having a flat surface with an image pattern engraved thereon, and an ink supply system, wherein the ink supply system comprises (a) an ink cup containing the ink having a first temperature of from about 20° C. to about 30° C., (b) an ink container containing the ink having a second temperature being at least about 3° C. lower than the first temperature and in flow communication with the ink cup, (c) a thermostat for maintaining the ink in the ink container at the second temperature, (d) a first flow conduit, and (e) a second flow conduit, wherein the ink cup comprises (i) a cylindrical hollow structure defining an ink reservoir for holding the ink and defining an outer edge, wherein the outer edge having a scraping element thereon for engaging the printing plate, (ii) an ink cup inlet, (iii) an ink cup outlet, and (iv) a stirrer for continuously mixing the ink in the ink cup, wherein the first flow conduit extends between the ink container and the ink cup inlet for providing a flow of the ink having the second temperature from the ink container to the ink cup and for maintaining the temperature of the ink in the ink cup at the first temperature, wherein the second flow conduit extends between the ink container and the ink cup outlet for providing a flow of the ink having the first temperature from the ink cup to the ink container; and
(2) curing the colored image thermally or actinically on the surface of the preformed contact lens to form a colored contact lens with the cured colored image attached thereon.

2. The method of claim 1 , further comprising a step of applying a clear coating at least on the surface with the colored image thereon of the colored contact lens to cover completely the colored image.

3. A method for producing colored contact lenses, comprising the steps of:
(1) obtaining a mold which comprises a female mold half having first molding surface and a male mold half having a second molding surface, wherein the male and female mold halves are configured to receive each other such that a lens-forming cavity is formed between the first and second molding surfaces when the mold is closed;
(2) forming, on the first or second molding surface, a colored transferrable polymeric film, wherein the colored transferrable polymeric film is formed by:
(a) applying a layer of a first polymerizable composition onto the first or second molding surface, wherein the first polymerizable composition is free of any pigment particle,
(b) at least partially curing the layer of the first polymerizable composition to form a first polymeric film on the first or second molding surface,
(c) printing a colored image with at least one ink on the first polymeric film on the first or second molding surface by using a pad printing instrument that comprises a silicone pad, a printing plate having a flat surface with an image pattern engraved thereon, and an ink supply system, wherein the ink supply system comprises (i) an ink cup containing the ink having a first temperature of from about 20° C. to about 30° C., (ii) an ink container containing the ink having a second temperature being at least about 3° C. lower than the first temperature and in flow communication with the ink cup, (iii) a thermostat for maintaining the ink in the ink container at the second temperature, (iv) a first flow conduit, and (v) a second flow conduit, wherein the ink cup comprises a) a cylindrical hollow structure defining an ink reservoir for holding the ink and defining an outer edge, wherein the outer edge having a scraping element thereon for engaging the printing plate, b) an ink cup inlet, c) an ink cup outlet, and d) a stirrer for continuously mixing the ink in the ink cup, wherein the first flow conduit extends between the ink container and the ink cup inlet for providing a flow of the ink having the second temperature from the ink container to the ink cup and for maintaining the temperature of the ink in the ink cup at the first temperature, wherein the second flow conduit extends between the ink container and the ink cup outlet for providing a flow of the ink having the first temperature from the ink cup to the ink container,
(d) curing the colored images on the first polymeric film on the first or second molding surface, and
(e) optionally applying a layer of a second polymerizable composition on top of the first polymeric film to completely cover the cured colored image on the first polymeric film, wherein the second polymerizable composition is free of any pigment particle and then is curing at least partially to form the second polymeric film which completely covers the cured colored image;

(3) dispensing a lens-forming composition into the lens-forming cavity of the mold; and
(4) curing the lens-forming composition within the lens-forming cavity to form the colored contact lens, whereby the colored transferrable polymeric film detaches from the first or second molding surface and becomes integral with the body of the colored contact lens.

4. The method of claim 3 , wherein the colored transferable polymeric firm comprises the first and second polymeric films and the cured colored image encapsulated between the first and second polymeric film.

5. The method of claim 4 , wherein the layers of the first and second polymerizable composition and the colored image are cured actinically by use of a UV/visible radiation, wherein the first and second polymerizable composition and the ink comprise a photoinitiator.

6. The method of claim 5 , wherein the lens-forming composition is cured thermally.

7. The method of claim 6 , wherein the first and second polymerizable compositions and the ink independent of one another comprise an actinically-crosslinkable binder polymer.

8. The method of claim 7 , wherein the ink comprises an organic solvent and at least one vinylic monomer.

9. The method of claim 8 , wherein the colored contact lens is a colored non-silicone hydrogel contact lens.

10. The method of claim 8 , wherein the colored contact lens is a colored silicone hydrogel contact lens.

Assignees

• Alcon Inc

Inventors

• Breitkopf Richard Charles
• Yin Changhong
• Zhang Steve Yun

Classifications

• B29D11/00903 Primary

  on the surface · CPC title

• C08L83/04

  Polysiloxanes · CPC title

• G02B1/043

  Contact lenses · CPC title

• B41F17/001 Primary

  Pad printing apparatus or machines · CPC title

• G02C7/046

  Contact lenses having an iris pattern · CPC title