Adhesion primer for laminate in cast lenses

Abstract

Embodiments of the disclosure relate to a primer composition for increasing the adhesion of a polarizing film laminate to a cast-polymerized lens. The primer includes an acrylic polymer, polyurethane acrylate oligomer, a solvent, a UV curing agent, and a monomer which promotes adhesion to a cast-polymerized lens.

Claims

1. An ophthalmic lens comprising: a cast-polymerized lens comprising at least one polymer formed from allyl diglycol carbonate, a functional laminate comprising a thermoplastic film layer attached to both sides of a functional layer wherein the functional laminate is a triacetyl cellulose (TAC)-polyvinyl alcohol (PVA)-TAC laminate, a primer coating deposited onto both external surfaces of the functional laminate, wherein said primer coating comprises: 33.3% of a base primer comprising: 10-23% of an acrylic resin, 10-23% of a UV-curable urethane acrylate oligomer, 65-66% of methyl isobutyl ketone, and 1-2% of a photoinitiator; 64.7% of an additional solvent chosen from ethyl acetate, cyclopentanone, and cyclohexanone; and 2.0% of allyl diglycol carbonate.

2. The ophthalmic lens of claim 1, wherein the acrylic resin has a molecular weight ranging from about 10,000 to about 100,000 g/mol.

3. The ophthalmic lens of claim 1, wherein the urethane acrylate oligomer comprises an ethylenically unsaturated monomer having a degree of unsaturation of 1 or more.

4. The ophthalmic lens of claim 3, wherein the urethane acrylate oligomer comprises an ethylenically unsaturated monomer having a degree of unsaturation of 2.

5. The ophthalmic lens of claim 1, wherein the functional laminate is a polarizing laminate.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 is a side view of a polarizing laminate.

(2) FIG. 2 is a side view of a polarizing laminate that has an adhesion-promoting primer applied.

(3) FIG. 3 is a side view of a cast polarizing lens.

DETAILED DESCRIPTION

(4) Various features and advantageous details are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. It should be understood, however, that the detailed description and the specific examples, while indicating embodiments, are given by way of illustration only, and not by way of limitation. Various substitutions, modifications, additions, and/or rearrangements will be apparent to those of ordinary skill in the art from this disclosure.

(5) In the following description, numerous specific details are provided to provide a thorough understanding of the disclosed embodiments. One of ordinary skill in the relevant art will recognize, however, that the invention may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

(6) In FIG. 1, a polarizing laminate (100) can be made by the lamination of a support or protective layers (110) onto a PVA polarizing film (120). The support layers (110) can be the same material or different materials. The support or protective layer (110) may be TAC. In FIG. 2, a primer (130) may be applied onto a TAC polar laminate (100) by flow coating, spin coating, gravure coating, or other means known to those of skill in the art.

(7) The primer is comprised of three main ingredients, a base primer supplied by Onbitt, a monomer and an additional solvent. The base primer components include about 10-23% of an acrylic resin, about 10-23% of a UV curable urethane acrylate oligomer, about 65-66% methyl isobutyl ketone (MIBK) solvent and about 1-2% of a photoinitiator. The monomer is CR39 and the additional solvent is ethyl acetate.

(8) In some aspects, the primer coating (130) may be dried from about 15 seconds to about 2 minutes at a temperature ranging from about 60° C. to about 80° C. Other drying conditions known to those of skill in the art may be employed to remove the solvent.

(9) The primer (130) is cured, for example, by using heat or a UV light source depending upon the initiator being used. Cure conditions can also be developed using existing installed commercial systems.

(10) In FIG. 3, the cured primed TAC polarizing laminate (200) was cast in CR39 (140). A semi-finished single vision (SFSV) lens (300) was aggressively surfaced (SET test, described below) then examined for delamination of the polarizing element within the lens.

Delamination Aggressive Surfacing and Edging Test (Set)

(11) In the experiments described below, the surfacing and edging test is employed to induce stress potentially leading to delamination in various lens samples.

(12) The surfacing and edging test is applicable to all ophthalmic lenses with embedded or surface mounted film. Lenses may be coated or uncoated, and may or may not include at least one of a hard coat, an antireflective component, a finishing vacuum coating, and a top coat. The observed failure rates provide an indication of the risk of failures during lens processing.

(13) Lenses are generated with a power offset. The lenses are then fined with increased pressure to exert mechanical forces on lens edges, resulting in high stress at the interfaces, potentially weakening the adhesion. Polishing is performed in a typical manner known to one skilled in the art. Edging is performed with the most aggressive setting on a typical edger.

(14) The test results outlined below were performed on polarized CR39 single vision lenses. The lenses were processed to +0.50 power with target thickness 2.8 mm. Lenses were blocked with metal alloy at an offset 0.1 diopter between the generator and the fining back curve. The fining pressure was raised to the safe maximum limits of the equipment (25 PSI, Gerber-Coburn). Polishing was performed according to standard operating procedures. Edging was performed on a fast-cycle edger which is selected to be especially aggressive (Triumph edger).

(15) Inspection

(16) A visual inspection for any anomalies resulting from any of the preceding steps is performed for each lens. Lenses are visually inspected for delamination. Any delamination is interpreted as a lens failure.

(17) Base Primer

(18) In developing a primer for improved adhesion of a TAC polar laminate to a cast CR39 lens, a base primer supplied by Onbitt was used as a starting point/control. The base primer components include about 10-23% of an acrylic resin which is chosen from Elvacite 2550 (methacrylate copolymer), Elvacite 2669 (acrylic copolymer) and Elvacite 2776 (acrylic resin) having a molecular weight range of 10,000 to 100,000 g/mol, about 10-23% of a UV-curable urethane acrylate oligomer (Nippon Gohsei UV-3000B), about 65-66% MIBK solvent, and about 1-2% of a photoinitiator (Irgacure 184).

(19) The base primer was applied onto a TAC polarizing laminate, dried, UV cured then cast in CR39 to make a lens. The base primer did not provide adequate SET adhesion for manufacturing polarizing CR39 ophthalmic lenses. One drawback of the base primer is its softness. When applied onto TAC or TAC laminate then dried and UV cured, the base primer failed cross-hatch adhesion tests. The base primer was then diluted in MIBK solvent to approximately 10% w/w. The diluted base primer was applied onto TAC at about 1 μm. The diluted base primer now provided satisfactory cross-hatch adhesion results, but failed SET adhesion tests in cast CR39. When a protective liner was applied onto a primed TAC polarizing laminate then removed, the TAC exhibited glossy regions (TAC) and hazy regions (primer). This was a result of the protective liner removing the primer from the TAC polarizing laminate.

(20) In additional tests, the base primer was applied onto Island Pyrochemical Industries (IPI) TAC polarizing laminate (polyurethane laminating adhesive) at a thickness of about 0.5-1.0 μm and cured in CR39. The base primer on the IPI polarizing laminate failed SET adhesion testing. The base primer was applied onto a LOFO TAC polarizing laminate with better SET results, however, the primer did not perform consistently. The base primer is used as a control.

Example 1

(21) A new primer formulation was developed by improving upon the Onbitt base primer. Some base primer was weighed out into a container. Ethyl acetate solvent and CR39 monomer (reactive monomer) were added and the resulting mixture was mixed thoroughly

(22) The primer may be applied onto a TAC polar laminate by flow coating, spin coating, gravure coating, or other means known to those of skill in the art. In some aspects, the primer coating may be dried from about 15 seconds to about 2 minutes at a temperature ranging from about 60° C. to about 80° C. Other drying conditions known to those of skill in the art may be employed to remove the solvent. After drying, the primer is cured, for example, by using a UV light source. One exemplary, non-limiting UV light source is a Fusion H+ bulb. Power, energy, and exposure time may be selected to optimize curing. Typical, non-limiting curing conditions include about 7 feet/min (UVA ˜1500 mJ/cm2, ˜1200 mW/cm2) to about 21 feet/min (500 mJ/cm2, 1100 mW/cm2).

(23) The primed TAC polarizing laminate was cast in CR39. The semi-finished single vision (SFSV) lens was aggressively surfaced (SET test described above) then examined for delamination of the polarizing element within the lens.

Example 2

(24) Example 2 included the same base primer and monomer as Example 1. Cyclopentanone was used as the solvent.

Example 3

(25) Example 3 included the same base primer and monomer as Example 1. Cyclohexanone was used as the solvent.

Comparative Example 1

(26) Comparative Example 1 is a dilution of the base primer using ethyl acetate. No reactive monomer was added.

Comparative Example 2

(27) Comparative Example 1 is a dilution of the base primer using MIBK solvent. No reactive monomer was added.

Comparative Example 3

(28) Comparative Example 3 included the same base primer and monomer as Example 1. MIBK was used as the solvent.

Results

(29) As shown in Table 1, SET adhesion was obtained when the base primer was diluted with ethyl acetate (Ex. 1), cyclopentanone (Ex. 2) or cyclohexanone (Ex. 3) in combination with the addition of allyl diglycol carbonate. Poor SET adhesion was observed with neat base primer, or with the base primer diluted only with ethyl acetate (Comp. Ex. 1) or MIBK (Comp. Ex. 2). Poor SET adhesion was also observed with base primer diluted with MIBK in combination with CR39 monomer (allyl diglycol carbonate, Comp. Ex. 3).

(30) TABLE-US-00001 TABLE 1 Primer Formulations SET Adhesion Base Comp. Comp. Comp. Component Ex. 1 Ex. 2 Ex. 3 Primer Ex. 1 Ex. 2 Ex. 3 Base primer 33.3% 33.3% 33.3% 100% 33.3% 33.3% 33.3% Ethyl Acetate 64.7% 66.7% MIBK 66.7% 64.7% Cyclopentanone 64.7% Cyclohexanone 64.7% CR39 monomer 2.0% 2.0% 2.0% 2.0% SET Adhesion excellent good good poor poor poor poor

(31) Table 2 includes examples of other laminates using various types of TAC. These were primed using the formula of Example 1, cast in CR39, then surfaced and edged as per SET. In all instances, the inventive primer passed SET adhesion. The primer disclosed herein perform successfully on laminates made from a variety TAC types.

(32) TABLE-US-00002 TABLE 2 Utility - SET Adhesion Observed For or a Variety of TAC Laminates SET TAC Laminate Adhe- Laminate TAC Type Haze Thickness sion LOFO 915 Non-UV/LH <0.5%  200 μm Pass LOFO 80 μm P905 .sup. <1% 200 μm Pass LOFO 190 μm P916190 NonUV-LH <0.4% 400 μm Pass IPI 190 μm 11SG190UV400-LH <0.5%  400 μm Pass IPI 180 μm 11SG180UV400 < 10% <0.5% 400 μm Pass SNT IPI 190 μm 190 non-UV .sup. <1% 400 μm Pass IPI 80 μm 11SG80UV380-LH <0.4% 200 μm Pass IPI 80 μm 11SG80UV-LH <0.5%  200 μm Pass IPI 80 μm 11SG80S-LH non-UV <0.4% 200 μm Pass

(33) The presently disclosed primer formulations, provide improved adhesion on TAC laminates, and are contemplated as a general TAC laminate adhesion-enhancing primer. The claims are not to be interpreted as including means-plus- or step-plus-function limitations, unless such a limitation is explicitly recited in a given claim using the phrase(s) “means for” or “step for,” respectively.