Methacrylic Acid Ester Polymer for Optical Media
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Solution Overview
Problem
Current methacrylic acid ester polymers with reactive double bonds at the terminus suffer from low hardness, brittleness, and yellowing, making them unsuitable for high-temperature and high-humidity environments, and they are challenging to produce efficiently without coloring issues.
Innovation Solution
A methacrylic acid ester polymer with an acid value of no higher than 50 mg KOH/g, transition metal content of no more than 1 ppm, and at least 80% by mole of terminal double-bond structure, produced using a suspension polymerization method with a cobalt complex as a chain transfer agent, is developed. This polymer is combined with a radical-polymerizable compound and a photopolymerization initiator to form an active energy ray-curable resin composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a low molecular weight methacrylic acid ester polymer is used to reduce viscosity and warping, then the viscosity and warping are improved, but the hardness of the cured product declines and it becomes brittle
Solution Approach 1:
The patent changes the molecular weight parameter of the methacrylic acid ester polymer to a specific range (3000-30000) to optimize the balance between viscosity, warping, and hardness. This parameter optimization allows the cured product to achieve low warping while maintaining high hardness and avoiding brittleness.
2Productivity
If conventional polymerization methods are used to produce methacrylic acid ester polymer, then the polymer can be obtained, but it exhibits yellowing and high transition metal content
Solution Approach 1:
The patent extracts and removes transition metals from the polymerization system by using a non-metallic chain transfer agent (carbon tetrachloride or 1,1,1-trichloroethane) instead of conventional metallic catalysts. This eliminates the source of yellowing and coloring while maintaining production efficiency through the CCTP method.
3Shape
If urethane acrylate is used in the active energy ray-curable resin composition, then warping is reduced, but the hardness becomes comparatively soft
Solution Approach 1:
The patent creates a composite resin composition by combining methacrylic acid ester polymer (for hardness) with urethane acrylate (for low warping). This composite formulation achieves a synergistic effect where the cured product exhibits both low warping and high hardness, overcoming the limitations of using urethane acrylate alone.
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 resulting resin composition exhibits low warping, high hardness, and resistance to corrosion and yellowing, making it suitable for optical recording media and protective coatings, while maintaining low viscosity and high transparency.
Implementation Method 1
various methods have been proposed as production methods thereof. For example, Patent Documents 1 to 3 disclose methods for producing methacrylic acid ester polymers having reactive double bonds at the terminus by way of the Catalytic Chain Transfer Polymerization (CCTP) method, using a specific transition metal chelate complex.
Implementation Method 2
active energy ray-curable resin composition, and an optical recording medium using this active energy ray-curable resin composition
Data Source
AI summary
A cured product that is reduced in warping and has high hardness can be obtained from an active energy ray-curable resin composition which uses a methacrylic acid ester polymer that has an acid value of 50 mg KOH/g or less and a transition metal content of 1 ppm or less, while containing 80% by mole or more of a polymer that has a double bond-terminated structure represented by formula (1). (In formula (1), R represents an alkyl group, a cycloalkyl group or an aryl group.)