Bi-layer adhesive for lens lamination

a technology of bilayer adhesive and lens, applied in the direction of lens, film/foil adhesive, polarizing element, etc., can solve the problems of low adhesion, polarized film and plastic lens adhesion has been a long-standing problem, and the technique previously disclosed has a number of drawbacks, so as to improve the mechanical and optical properties of laminated functional optical elements.

Inactive Publication Date: 2011-10-06
ESSILOR INT CIE GEN DOPTIQUE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0007]It is therefore an object of the present invention to improve both the mechanical and optical properties of laminated functionalized optical elements.
[0011]The latex adhesive layer comprises a material selected from the group consisting of an acrylic latex, a (meth)acrylic latex, a polyurethane latex, a core / shell latex, and combinations thereof. The latex layer comprises a dry, solid layer of between 0.5 microns and 10 microns thick with a uniform thickness throughout to provide optical quality. In a preferred embodiment the latex layer is between 1.0 microns and 5.0 microns thick with a uniform thickness varying by less than 0.5 microns throughout to provide optical quality.
[0012]The hot melt adhesive layer includes one or more of a UV curable HMA, a UV curable monomer. a thermal curable HMA, and a thermal curable monomer, a polymer HMA, a thermoplastic polymer HMA, and a colloid. In a preferred embodiment, the HMA is a heat-activatable polyurethane adhesive. The HMA layer comprises a dry, solid layer between 1.0 microns and 20 microns with a uniform thickness throughout to provide optical quality. In a preferred embodiment the HMA layer is between 1.5 microns and 10 microns with a uniform thickness varying by less than 0.5 microns throughout to provide optical quality.
[0017]Another aspect of the invention includes a method for manufacturing a functionalized optical element comprising the following steps. An optical base element and a functionalized layered structure that includes at least one functional layer is provided. A layer of latex adhesive is firstly coated onto one surface of said functionalized layered structure. A layer of hot-melt adhesive is secondly coated onto the dried latex adhesive layer to form a uniformly thin bi-layer adhesive lamina of optical quality. The functionalized layered structure is hot pressed against the optical base element with the second HMA coating layer in contact with a surface of the optical base element to form a functionalized optical element with high adhesive strength.

Problems solved by technology

Adhesion between polarized films and plastic lenses has been a long standing problem within the industry.
However, the techniques previously disclosed have a number of drawbacks, mainly due to low adhesion or low mechanical performance.
Attempts to cure these defects have marginally improved adhesion strength with a loss of optical quality.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

examples 1 & 2

[0044]Adhesion comparison test on TAC / PVA / TAC film between a urethane latex based on W-234 from Baxenden and HMA-U42: TAC film was corona treated firstly, then the films were spin coated with either the urethane latex solution or U42 in the spin conditions of 450-500 rpm for 3-5 seconds and 1000-1500 rpm for 8-10 seconds and then dried at 60 degrees C. for 10-30 min. After drying and cooling, the adhesion behavior on TAC film was measured by classic crosshatch tape method as shown in the following Table 1. The result showed that Latex has better adhesion score than HMA on a TAC film.

TABLE 1Adhesive test on TAC polarized filmCrosshatch TapeEx.AdhesivesFilmTreatmentCoatingadhesion scoreEx. 1LatexTACCoronaSpin and dry0Ex. 2HMA / U42TACCoronaSpin and dry5* Crosshatch tape score 0 means perfect adhesion between Latex and TAC film and 5 means adhesion failure between U42 and TAC.

example 3

[0045]A TAC polarized film (TAC / PVA / TAC) from Onbitt company was first thermoformed to a curve close to the front side of a polycarbonate lens. The convex side of the TAC film is subjected to a corona discharge using Tantec equipment. A urethane latex adhesive based on W-234 from Baxenden is spin coated onto the treated film surface, and set to dry for 30 minutes at 60 degrees C. Next, an HMA solution of Dispercoll® U 42 is spin coated on top of the dried latex layer, and set to dry for 10 minutes at 60 degrees C. The dried bi-adhesive layer was then set against a polycarbonate lens, utilizing an accumulator device having a lens support and an inflatable silicon membrane. The pressure was slowly increased to 30 psi to achieve full contact across the entire surfaces of the film and lens. The accumulator set-up was place in an oven at 80 degrees C. for 30 minutes.

[0046]After lamination the polarized optical element exhibited very strong adhesion between the film and the lens. No delam...

example 4

[0048]Example 3 was repeated except the lamination step was conducted by using a small hot press device with a pressure of 26 psi and heating at 90 degrees C. for 5 minutes. The resulting functionalized optical element had the same good adhesion between the functionalized layered structure and the optical base element. In the peel test a force of 20N was recorded to peel the film at 2.54 mm / min.

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Abstract

A method for laminating a film on to an optical article and a bi-layer adhesive for use in the method. The bi-layer adhesive includes a latex adhesive layer or a specific silane adhesive and an HMA layer sequentially disposed on the film and dried to form a solid layer of uniform thinness throughout to provide optical quality. Various types of films may be employed to provide an optical function. Following optional pre-treatment steps, the adhesives are coated on to the film. An optical hot press technique is used to deliver heat and pressure over a short period of time to form a functionally-enhanced optical article with high adhesive strength.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The invention relates to a method for laminating a functionalized layered structure to an optical base element with a bi-layer adhesive and the resulting functionalized optical element.[0003]2. The Prior Art[0004]Various films and coatings are combined with optical elements to enhance their performance. Adhesion between polarized films and plastic lenses has been a long standing problem within the industry. The selection of one adhesive always represents a compromise between ease of use, mechanical integrity and optical quality.[0005]One approach is detailed in WO2006 / 082105 which employs a latex glue in a film transfer process. In EP 1868798 an HMA glue for a film transfer process is described. In WO2002 / 096521 a polarized film is laminated with a pressure sensitive adhesive. In a mechanical approach described in US2007 / 0195262, a complex support is used to warp the film during lamination to improve adhesion.[0006]Howe...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G02B1/08B32B7/12B32B3/00G02B1/10B32B37/02B32B37/06B32B37/12B32B38/10B32B37/14
CPCB29D11/0073Y10T428/2896Y10T428/2878Y10T428/28Y10T428/265Y10T156/1002Y10T428/31551C09J119/02C09J175/04G02B1/041G02B5/3041
Inventor GLACET, ARNAUDJIANG, PEIQIKEEGAN, BRUCE
Owner ESSILOR INT CIE GEN DOPTIQUE
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