Acrylic Hard Coat Film Adhesion to Antireflection Layer
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Solution Overview
Problem
Existing hard coat films for plastic lenses face challenges in adhesion to antireflection films, scratch resistance, and compatibility with heat-labile substrates, particularly due to long curing times and limitations in composition options for cationic curing systems.
Innovation Solution
A coating composition containing a specific ratio of acrylate components and zirconia, including polyfunctional acrylate compounds, dendritic aliphatic compounds, and acrylate compounds with isocyanuric ring structures, which form an acrylic hard coat film with enhanced adhesion and scratch resistance, suitable for application on a wide range of substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a silicone thermosetting hard coat film is used, then scratch resistance and adhesion to plastic lens are enhanced, but it cannot be applied to heat-labile substrates and requires extensive curing equipment
Solution Approach 1:
The patent changes the curing mechanism from thermal (heat-based) to photopolymerization (light-based) by using photo-curing hard coat films with initiators like 2,4,6-trimethylbenzoyl diphenyl phosphine oxide. This parameter change allows the hard coat to be applied to heat-labile substrates while maintaining scratch resistance, as the curing process occurs at room temperature through UV or visible light irradiation rather than high-temperature heating
Solution Approach 2:
The patent replaces the thermal curing mechanism (heat-based chemical reaction) with a photopolymerization mechanism (light-based chemical reaction). This substitution eliminates the need for extensive heating equipment and allows application on substrates that cannot withstand high temperatures, while still achieving the desired crosslinked network structure for scratch resistance
2Productivity
If a cationic curing system is used, then curing time is reduced compared to thermosetting, but the system requires long curing time and has limited composition options
Solution Approach 1:
The patent employs a photopolymerization system that is universally applicable to various acrylate and vinyl monomers, providing extensive composition options. The photo-initiator system can cure a wide range of monomer types (acrylates, vinyl ethers, vinyl esters) without requiring specific cationic monomer structures, thus offering both fast curing and versatile composition selection
Solution Approach 2:
The patent creates a composite coating system combining photo-initiators with various acrylate monomers and inorganic particles. This composite approach allows tuning of both curing speed and final film properties by selecting different monomer combinations and particle types, achieving both productivity and compositional versatility
3Loss of time
If a photocurable acrylic hard coat film is used, then curing time is reduced, but adhesion to inorganic antireflection film is insufficient
Solution Approach 1:
The patent introduces inorganic particles (silica, alumina, zirconia, titania) with specific surface properties into the acrylic hard coat formulation. These particles create localized regions of enhanced surface energy and chemical reactivity on the hard coat surface, improving adhesion to the inorganic antireflection film deposited subsequently, while the bulk acrylic matrix maintains fast photopolymerization curing
Solution Approach 2:
The inorganic particles act as intermediary elements between the organic acrylic hard coat and the inorganic antireflection film. These particles provide a transition zone with compatible surface properties for both materials, enhancing interfacial adhesion. The particles may also undergo surface treatment to further improve compatibility with both the organic polymer matrix and the deposited inorganic layer
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 composition achieves excellent adhesion to antireflection films while providing high scratch resistance and flexibility, maintaining adhesion even after severe weathering tests, making it suitable for various optical applications like spectacle lenses.
Implementation Method 1
the coating composition is capable of forming an acrylic hard coat film... Various photocuring hard coat films have been proposed as a hard coat film for a plastic lens
Data Source
AI summary
To provide a coating composition capable of forming an acrylic hard coat film that is excellent in adhesion to an antireflection film while having high scratch resistance, and an optical member having a hard coat film that is obtained by using the coating composition. A coating composition containing (A) an acrylate component and (B) zirconia, wherein a mass ratio (B)/(A) of (B) the zirconia to (A) the acrylate component is from 0.1 to 2.0, (A) the acrylate component contains the following components (a-1), (a-2) and (a-3), and a content ratio X of the component (a-1), a content ratio Y of the component (a-2) and a content ratio Z of the component (a-3) satisfies the following conditions (1) and (2), and an optical member having a hard coat film that is obtained by using the coating composition: (a-1): a polyfunctional acrylate compound having 3 or more acrylate groups in one molecule; (a-2): a dendritic aliphatic compound having an acrylate group at an end thereof; and (a-3): an acrylate compound having 1 or 2 acrylate groups in one molecule; or a mixture of an acrylate compound having 1 or 2 acrylate groups in one molecule and an acrylate compound other than the components (a-1) and (a-2), the condition (1): in (A) the acrylate component, X is from 40 to 60% by mass, and a total of Y and Z is from 60 to 40% by mass, and the condition (2): in the total of Y and Z, Z is 0% by mass or more and less than 100% by mass.