Hard Coat Laminate Crack Prevention During Curved Cutting
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Solution Overview
Problem
Conventional hard coat laminates for touch panels and transparent conductive substrates face issues with heat resistance, dimensional stability, and cracking during cutting operations, especially when curved cutting lines with small curvature radii are involved, due to insufficient adhesive strength reduction after cutting.
Innovation Solution
A method for producing a hard coat laminate with a poly(meth)acrylic imide resin layer, where a pressure-sensitive adhesive layer is temporarily bonded and then reduced in strength using heat or active energy rays after cutting, allowing for the suppression of cracks during support peeling, and utilizing router machining with a mill having a superhard alloy blade to achieve high surface hardness and smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If glass substrate is used to satisfy heat resistance and dimensional stability, then heat resistance and dimensional stability are improved, but impact resistance and fragility worsen
Solution Approach 1:
The invention uses a composite structure consisting of a transparent resin film substrate and a hard coat layer. The transparent resin film substrate provides impact resistance and flexibility, while the hard coat layer provides surface hardness and abrasion resistance. This composite structure replaces traditional glass substrates to achieve both heat resistance and improved impact resistance.
2Strength
If surface hardness is enhanced for display face plate, then surface hardness and abrasion resistance are improved, but crack generation during cutting and support peeling worsens
Solution Approach 1:
The invention changes the adhesive strength parameter of the support through thermal treatment. By heating the hard coat laminate to a specific temperature range (50°C to 150°C), the adhesive strength between the support and the hard coat layer is reduced to a controlled range (0.5 N/2.5 cm to 2.0 N/2.5 cm), preventing crack generation during support peeling while maintaining high surface hardness.
3Reliability
If adhesive strength is reduced to prevent cracks, then crack generation is suppressed, but support peeling difficulty may increase
Solution Approach 1:
The invention precisely controls the adhesive strength parameter through thermal treatment to achieve an optimal balance. By heating to specific temperature ranges and controlling the treatment time, the adhesive strength is reduced to a specific range (0.5 N/2.5 cm to 2.0 N/2.5 cm) that is low enough to prevent cracks but high enough to allow easy support peeling.
4Adaptability or versatility
If curved cutting lines with small curvature radius are used, then design flexibility is improved, but crack generation at cutting lines worsens
Solution Approach 1:
The invention changes the adhesive strength parameter of the support to prevent crack generation during cutting operations. By reducing the adhesive strength through thermal treatment before cutting, the hard coat laminate can be cut along curved lines with small curvature radii without generating cracks, improving design flexibility while maintaining cutting quality.
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 method ensures high transparency, surface hardness, bending resistance, and dimensional stability of the hard coat laminate, preventing cracks during cutting and support peeling, and enabling the use of curved cutting lines with small curvature radii without defects.
Implementation Method 1
a pressure-sensitive adhesive layer is temporarily bonded and then reduced in strength using heat or active energy rays after cutting
Implementation Method 2
utilizing router machining with a mill having a superhard alloy blade to achieve high surface hardness and smoothness
Data Source
AI summary
The present invention pertains to a process for producing an article from a layered hard coat object including a hard coat layer and a transparent-resin film layer in this order from the outermost layer side, the process comprising: a step (A) in which a pressure-sensitive adhesive layer of a support having the pressure-sensitive adhesive layer on at least one surface thereof is temporarily applied to at least one surface of the layered hard coat object to obtain a temporarily support-bearing layered hard coat object; a step (B) in which at least one processing method selected from the group consisting of router processing, water-jet processing, laser processing, and punching is applied to the temporarily support-bearing layered hard coat object to cut the temporarily support-bearing layered hard coat object into a given shape, thereby obtaining a temporarily support-bearing cut article; and a step (C) in which at least one kind of energy selected from the group consisting of heat and actinic rays is applied to the temporarily support-bearing cut article to reduce the strength of tackiness between the support and the article to 2 N/2.5 cm or less.