Primer Coating for TAC Film Adhesion on Polyurethane Lenses
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Solution Overview
Problem
Existing primer coatings for ophthalmic lenses, particularly for polyurethane and poly(thio)urethane lenses, fail to provide adequate adhesion for triacetyl cellulose (TAC) films or laminates, leading to inconsistent bonding and high haze levels, which are critical issues for manufacturing high-index and ultra-high-index lenses with polarizing functions.
Innovation Solution
A primer coating composition comprising acrylic polymers, urethane acrylate oligomers, reactive components such as 2-hydroxyethylmethacrylate, and initiators is applied to improve adhesion between TAC films or laminates and polyurethane lenses, ensuring strong bonding and low haze levels, even with reactive two-component polyurethane adhesives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a primer coating is applied to improve adhesion between TAC film and lens, then adhesion is improved, but the coating process complexity increases
Solution Approach 1:
The primer coating is applied to the TAC film surface before lens casting to pre-establish adhesion bonds. This preliminary action ensures that when the lens is formed and the adhesive is applied, the bonding interface is already prepared for strong adhesion, resolving the contradiction by performing the adhesion-enhancing action in advance rather than during the complex coating process
Solution Approach 2:
The primer coating acts as an intermediary layer between the TAC film and the lens material. This intermediate layer facilitates adhesion by providing chemical or physical bonding sites that bridge the TAC film and the lens polymer, improving adhesion without requiring direct contact between the TAC film and lens material
2Strength
If reactive adhesive is used to bond TAC laminate to lens, then bonding strength is improved, but adhesion consistency deteriorates
Solution Approach 1:
The primer coating is applied before the reactive adhesive to pre-prepare the bonding surface. This preliminary action creates consistent bonding sites that ensure uniform adhesion performance, so that when the reactive adhesive is applied, the results are consistent and reliable rather than variable
Solution Approach 2:
The primer coating modifies the surface parameters of the TAC film by changing its chemical composition or surface energy. This parameter change creates a more consistent and predictable bonding interface that ensures reliable adhesion performance with reactive adhesives
3Reliability
If TAC laminate is embedded in lens to provide polarizing function, then functional performance is improved, but manufacturing precision deteriorates
Solution Approach 1:
The primer coating is applied to the TAC laminate before embedding in the lens. This preliminary action prepares the bonding surface in advance, which simplifies the embedding process and improves manufacturing precision by reducing the complexity of aligning and bonding the TAC laminate to the lens during casting
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The primer coating composition achieves excellent adhesion and a commercially acceptable haze level, enabling the successful manufacturing of TAC-on-TOP lenses with polarizing functions on poly(thio)urethane lenses, enhancing the durability and optical quality of ophthalmic lenses.
Implementation Method 1
at least one UV initiator or at least one thermal initiator
Data Source
AI summary
A primer coating composition for bonding a functional laminate to a lens during cast-polymerization, including an acrylic polymer; a urethane acrylate oligomer; a reactive component capable of reacting with a lens-casting monomer for casting the cast-polymerized lens, a UV initiator or a thermal initiator, and a solvent. A method for cast-polymerizing a lens, including applying the primer coating composition to at least one external surface of a functional laminate; cutting and forming the functional laminate, placing the shaped functional laminate to which the primer coating is applied and a monomer for casting a lens in a casting cell so that the monomer contacts the primed surface of the functional laminate, and cast-polymerizing the monomer in the casting cell. An ophthalmic lens, including a cast-polymerized lens including at least one polymer, a functional laminate, and a primer coating obtained by curing the primer coating composition and deposited on at least one external surface of the functional laminate.