Composite mold for manufacturing a microstructured thermoset article, manufacturing method and method for obtaining the mold

Patent metadata

Field	Value
Publication number	US-12539680-B2
Application number	US-202218563150-A
Country	US
Kind code	B2
Filing date	May 25, 2022
Priority date	May 26, 2021
Publication date	Feb 3, 2026
Grant date	Feb 3, 2026

Abstract

A composite mold for manufacturing a thermoset optical article which is usable as an ophthalmic lens substrate and which comprises a microstructured main surface, to a method for manufacturing such a thermoset optical article, and to a method for obtaining the composite mold. The composite mold ( 1 ) comprises:·—a mineral first outer mold part ( 2 ) having a first inner surface ( 2 a ), and·—an organic molding film ( 4 ) detachably bonded to the first inner surface ( 2 a ) and having a microstructured pattern configured to directly form said microstructured main surface after casting the thermosetting material ( 6 ) in contact with the organic molding film ( 4 ). The organic molding film ( 4 ) is hydrophobic at least on said microstructured pattern, and has a thickness of between 10 nm and 500 1-1 m.

First claim

The invention claimed is:

1 . A composite mold for manufacturing a thermoset optical article which is usable as an ophthalmic lens substrate and which comprises a microstructured main surface, by casting a thermosetting material into a molding cavity, the composite mold comprising:
a mineral first outer mold part having a first inner surface; and an organic molding film detachably bonded to the first inner surface and having a microstructured pattern configured to directly form said microstructured main surface after casting the thermosetting material in contact with the organic molding film, wherein the organic molding film is hydrophobic at least on said microstructured pattern, and has a thickness of between 10 nm and 100 μm.

2 . The composite mold according to claim 1 , wherein the organic molding film:
exhibits a water contact angle greater than 100° at least on said microstructured pattern; and/or has a thickness of between 1 μm and 100 μm.

3 . The composite mold according to claim 1 , wherein the organic molding film is based on at least one polymer selected from elastomers, thermoplastic polymers and thermoset polymers, and wherein the organic molding film is of monolayer or multilayer type, being hydrophobic on said microstructured pattern and optionally also through the thickness of said organic molding film.

4 . The composite mold according to claim 3 , wherein the organic molding film is based on at least one crosslinked elastomer.

5 . The composite mold according to claim 4 , wherein the at least one crosslinked elastomer is selected from silicone rubbers, including two-part polydimethylsiloxanes (PDMS), and from polyurethane rubbers, including two-part liquid urethane rubbers.

6 . The composite mold according to claim 3 , wherein the organic molding film is based on at least one thermoset polymer.

7 . The composite mold according to claim 6 , wherein the at least one thermoset polymer is selected from thiol-ene thermosets, including one-part liquid photopolymer adhesives, and from thermoset polyurethanes.

8 . The composite mold according to claim 3 , wherein the organic molding film is based on at least one thermoplastic polymer.

9 . The composite mold according to claim 8 , wherein the at least one thermoplastic polymer is selected from fluorinated polymers, including terpolymers of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride, and from thermoplastic polyurethanes (TPU).

10 . The composite mold according to claim 3 , wherein the organic molding film has a Young modulus measured according to ASTM D882-12 of between 100 MPa and 4000 MPa.

11 . The composite mold according to claim 1 , wherein the mineral first outer mold part has said first inner surface which comprises a microstructure onto which a first face of the organic molding film is detachably bonded without an adhesive therebetween, the organic molding film conforming to the microstructure on the first face and having an opposite second face forming said microstructured pattern; and
wherein the composite mold further comprises a mineral second outer mold part which has a second inner surface opposite to the first inner surface, the molding cavity being defined between the organic molding film and the second inner surface.

12 . The composite mold according to claim 11 , wherein the first inner surface of the mineral first outer mold part has said first inner surface which is concave, and wherein the thickness of the organic molding film ranges from 1/10 to 1/100 of the average amplitude of said microstructure of the mineral first outer mold part.

13 . A method for manufacturing a thermoset optical article which is usable as an ophthalmic lens substrate and which comprises a microstructured main surface for example configured to control myopia, wherein the method comprises:
a) casting a thermosetting material into a molding cavity of a composite mold according to claim 1 , so that the thermosetting material contacts the organic molding film and a second inner surface of a mineral second outer mold part which is opposite to the first inner surface, without contacting said first inner surface; b) curing the thermosetting material cast in the molding cavity; and c) demolding the molded thermoset material obtained in step b), comprising releasing the molded thermoset material from the organic molding film, so that the microstructured pattern of the organic molding film directly forms the microstructured main surface of the obtained thermoset optical article.

14 . The method according to claim 13 , wherein the organic molding film resists attack during casting step a) from the thermosetting material, which is selected from:
cycloolefin copolymers including ethylene/norbornene or ethylene/cyclopentadiene copolymers; homopolymers and copolymers of allyl carbonates of linear or branched aliphatic or aromatic polyols, including homopolymers of diethylene glycol bis(allyl carbonate), homopolymers and copolymers of (meth)acrylic acid and esters thereof, which are optionally derived from bisphenol A; homopolymers and copolymers of thio(meth)acrylic acid and esters thereof; homopolymers and copolymers of allyl esters which are optionally derived from bisphenol A or phthalic acids, and allyl aromatics including styrene; copolymers of urethane and thiourethane; homopolymers and copolymers of epoxy; and homopolymers and copolymers of sulfide, disulfide and episulfide.

15 . A method for obtaining a composite mold according to claim 1 , wherein the method comprises:
A) Providing a polymer composition which is either hydrophobic or coated with a hydrophobic surface layer and which is capable of forming the organic molding film to be detachably bonded to the mineral first outer mold part, the polymer composition being able to resist attack from the thermosetting material to be cast; B) Applying the polymer composition on the inner surface of the mineral first outer mold part, to form a precursor layer for the organic molding film; and C) Treating the applied precursor layer to form the organic molding film, which has said thickness of between 10 nm and 100 μm and a surface tension able to release therefrom the cast and cured thermoset optical article.

16 . The method according to claim 15 , wherein said inner face of the mineral first outer mold part is formed of mineral glass and comprises a microstructure onto which the organic molding film is conformingly bonded in steps B) and C), to form said microstructured pattern.

17 . The method according to claim 16 , wherein the polymer composition consists of a solution comprising a solvent and at least one polymer selected from elastomers, thermoplastic polymers and thermoset polymers, and wherein step B) comprises coating the solution on the inner surface of the mineral first outer mold part.

18 . The method according to claim 17 , wherein step C) comprises:
crosslinking the precursor layer in case the at least one polymer is selected from elastomers and thermoset polymers; or evaporating the solvent, in case the at least one polymer is selected from thermoplastic polymers and is spin-coated in step B).

19 . The method according to claim 16 , wherein, in case the polymer composition is devoid of a solvent and when the at least one polymer is selected from thermoplastic polymers, steps B) and C) comprise micro-thermoforming the polymer composition using pressure and/or vacuum by compression against the microstructure of said inner face of the mineral first outer

Assignees

• Essilor Int

Inventors

• Fromentin Pierre
• Shan Haifeng

Classifications

• B29L2011/0016

  Lenses · CPC title

• B29K2101/10

  Thermosetting resins · CPC title

• B29D11/00865

  Applying coatings; tinting; colouring (printing, marking or copying processes B41M; identification in general G09F3/00; producing decorative effects in general B44C; positioning or marking of lenses B24B13/0055) · CPC title

• B29D11/00548

  with surfaces formed by films · CPC title

• B29D11/00519

  Reusable moulds · CPC title