US-12617165-B2 - Method for printing a thermoplastic film on an optical mold

US12617165B2US 12617165 B2US12617165 B2US 12617165B2US-12617165-B2

Abstract

The present disclosure relates to a method of printing a thermoplastic film on an optical mold comprising adjusting a temperature of the optical mold to a first temperature, printing a first layer of the thermoplastic film on the optical mold once the temperature of the optical mold has reached the first temperature, applying a vacuum to the optical mold to hold the thermoplastic film on the optical mold, adjusting the temperature of the optical mold to a second temperature, printing a second layer of the thermoplastic film on the first layer of the thermoplastic film once the temperature of the optical mold has reached the second temperature, adjusting the temperature of the optical mold to a third temperature, annealing the first layer and the second layer once the temperature of the optical mold has reached the third temperature, and removing the vacuum from the optical mold permitting removal of the thermoplastic film including the annealed first layer and the annealed second layer from the optical mold.

Inventors

Haifeng Shan
Hao-Wen Chiu
Aref Jallouli

Assignees

ESSILOR INTERNATIONAL

Dates

Publication Date: 20260505
Application Date: 20210927
Priority Date: 20200928

Claims (12)

1 . A method of printing a thermoplastic film on an optical mold, comprising: adjusting, by temperature control circuitry, a temperature of the optical mold to a first temperature; printing a first layer of the thermoplastic film on the optical mold once the temperature of the optical mold has reached the first temperature; applying, right after printing of the first layer, a vacuum to the optical mold to hold the thermoplastic film on the optical mold and deform the thermoplastic film to conform to a curvature or microstructures of a surface of the optical mold; adjusting, by the temperature control circuitry, the temperature of the optical mold to a second temperature; printing a second layer of the thermoplastic film on the first layer of the thermoplastic film once the temperature of the optical mold has reached the second temperature; adjusting, by the temperature control circuitry, the temperature of the optical mold to a third temperature; annealing the first layer and the second layer once the temperature of the optical mold has reached the third temperature; and removing the vacuum from the optical mold permitting removal of the thermoplastic film including the annealed first layer and the annealed second layer from the optical mold.
2 . The method according to claim 1 , wherein the first temperature is between 10° C. lower than a glass transition temperature of the thermoplastic film and 30° C. higher than the glass transition temperature of the thermoplastic material of the first layer.
3 . The method according to claim 1 , wherein the first layer of the thermoplastic film is a thermoplastic skin layer including a plurality of thermoplastic layers, and wherein a thickness of the first layer of the thermoplastic film is between 10 and 500 microns.
4 . The method according to claim 1 , wherein the second temperature is equal to or greater than the glass transition temperature of the thermoplastic material of the second layer.
5 . The method according to claim 1 , wherein the third temperature is between the glass transition temperature and 60° C. lower than the glass transition temperature of the thermoplastic material of the second layer.
6 . The method according to claim 1 , wherein the temperature control circuitry controls one or more electric heating elements and/or a microfluidic channel circulating with a temperature regulating fluid to regulate the temperature of the optical mold.
7 . The method according to claim 1 , wherein the printing the first layer or printing the second layer includes printing using a single thermoplastic or at least two different thermoplastics to form 2D or 3D structures and/or functions.
8 . The method according to claim 7 , wherein at least one of the at least two different thermoplastics has a higher mechanical strength than another one of the at least two different thermoplastics and/or at least one of the at least two different thermoplastics has a higher glass transition temperature than another one of the at least two different thermoplastics.
9 . The method according to claim 7 , wherein the at least two different thermoplastics form a homogenous or heterogeneous structures and/or functions.
10 . The method according to claim 7 , wherein the at least two different thermoplastics form a heterogeneous structure and/or function, wherein a difference of refractive index (RI) between different thermoplastics is less than 0.01 and/or wherein AE between different thermoplastics is less than 1, where ΔE=√{square root over ((ΔL) 2 +(Δa*) 2 +(Δb*) 2 )}, as defined by CIE76 formula.
11 . The method according to claim 7 , wherein the at least two different thermoplastics are modifiable with light filters or dyes or additives or fillers.
12 . The method according to claim 11 , wherein: the light filters include one from a group consisting of UV cut, blue cut filter, and NIR cut filter; the dyes include one from a group consisting of color balancing dyes, color enhancement dyes, photochromic dye, and dichroic dyes; the additives include one from a group consisting of plasticizer, heat stabilizer, light stabilizer, flow improver, and mold release; and the fillers include one from a group consisting of particles, fibers, and nano tubes.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a national phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2021/076472 filed 27 Sep. 2021, which claims priority to European Patent Application No. 20306110.6 filed 28 Sep. 2020. The entire contents of each the above-referenced disclosures is specifically incorporated by reference herein without disclaimer. BACKGROUND Field of the Disclosure The present disclosure relates to method for printing a thermoplastic film on an optical mold. Description of the Related Art Ophthalmic lens products are regularly comprised of a lens and a film, and the film is typically laminated on an optical surface of the lens. The film can be a thin and flat wafer. The thin and flat wafer comprising thermoplastic films can be printed by an additive manufacturing three-dimensional (3D) printer for ophthalmic lens applications. However, when printing the thin and flat wafer, some issues may exist due to limited force and heat during the printing processes, e.g., voids between thermoplastic filament strands and layers, poor adhesion between thermoplastic filament strands and between layers, film warpage, and rough surfaces, etc. The foregoing “Background” description is for the purpose of generally presenting the context of the disclosure. Work of the inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present disclosure. Aspects of the invention may address some of the above-described shortcomings in the art, particularly using solutions set forth in the claims. SUMMARY The present disclosure relates to a method of printing a thermoplastic film on an optical mold. The present disclosure further relates to a method of printing a thermoplastic film on an optical mold, comprising adjusting, by temperature control circuitry, a temperature of the optical mold to a first temperature, printing a first layer of the thermoplastic film on the optical mold once the temperature of the optical mold has reached the first temperature, applying a vacuum to the optical mold to hold the thermoplastic film on the optical mold, adjusting, by the temperature control circuitry, the temperature of the optical mold to a second temperature, printing a second layer of the thermoplastic film on the first layer of the thermoplastic film once the temperature of the optical mold has reached the second temperature, adjusting, by the temperature control circuitry, the temperature of the optical mold to a third temperature, annealing the first layer and the second layer once the temperature of the optical mold has reached the third temperature, and removing the vacuum from the optical mold permitting removal of the thermoplastic film including the annealed first layer and the annealed second layer from the optical mold, wherein the first temperature may be between 10° C. lower than a glass transition temperature of the thermoplastic film and 30° C. higher than the glass transition temperature, the first layer of the thermoplastic film may be a thermoplastic skin layer including a plurality of thermoplastic layers, a thickness of the first layer of the thermoplastic film may be between 10 and 500 microns, the second temperature may be equal or greater than the glass transition temperature, the third temperature may be between the glass transition temperature and 60° C. lower than the glass transition temperature, the temperature control circuitry may control one or more electric heating elements and/or a microfluidic channel circulating with a temperature regulating fluid to regulate the temperature of the optical mold, the printing the first layer or printing the second layer includes printing using a single thermoplastic or at least two different thermoplastics to form 2D or 3D structures and/or functions, at least one of the at least two different thermoplastics may have a higher mechanical strength than another one of the at least two different thermoplastics and/or at least one of the at least two different thermoplastics may have a higher glass transition temperature than another one of the at least two different thermoplastics, the at least two different thermoplastics form a homogenous or heterogeneous structures and/or functions, the at least two different thermoplastics may form a heterogeneous structures and/or function, wherein AF between different thermoplastics may be less than 1, where Δ⁢E=(Δ⁢L)2+(Δ⁢a*)2+(Δ⁢b*)2, as defined by CIE76 formula, the at least two different thermoplastics are modifiable with light filters or dyes or additives or fillers, wherein the light filters may include one from a group consisting of UV absorber, blue cut filter, and NIR cut filter, wherein the dyes may include one from a group consisting of color balancing dyes, color enhancement dyes, pho