Photocurable Resin Composition for Head Lamp Lens Transparency
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Solution Overview
Problem
Conventional photocurable resin compositions used for head lamp lenses exhibit clouding and loss of transparency when exposed to LED light, requiring a cured film with improved smoothness, adhesion, abrasion resistance, scratch resistance, crack resistance, and weather resistance.
Innovation Solution
A photocurable resin composition comprising urethane (meth)acrylate, bifunctional and hexafunctional (meth)acrylate monomers, a photopolymerization initiator, and a leveling agent, with specific content ratios and the inclusion of an ultraviolet absorber and photostabilizer, to form a cured film that maintains transparency and resistance under LED irradiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional photocurable resin compositions are used for head lamp lenses, then the cured film provides basic protective properties, but the cured film turns white and cloudy upon LED irradiation, losing transparency
Solution Approach 1:
The patent changes the chemical composition parameters of the photocurable resin by specifying precise ratios of urethane (meth)acrylate (45-75 mass%), (meth)acrylate monomer (20-45 mass%), and bifunctional (meth)acrylate monomer (35% or more of the (meth)acrylate monomer content). These parameter changes optimize the cured film's resistance to LED-induced clouding while maintaining transparency.
Solution Approach 2:
The patent creates a composite photocurable resin system combining multiple components: urethane (meth)acrylate (A), (meth)acrylate monomer (B) including both bifunctional (b1) and hexafunctional (b2) types, photopolymerization initiator (C), and leveling agent (D). This composite material approach synergistically improves transparency and LED resistance beyond what single components can achieve.
2Reliability
If the cured film is designed to resist LED irradiation, then transparency is maintained, but other properties such as smoothness, adhesion, and mechanical resistance may be compromised
Solution Approach 1:
The patent optimizes multiple compositional parameters simultaneously: urethane (meth)acrylate content (45-75 mass%), (meth)acrylate monomer content (20-45 mass%), and the ratio of bifunctional monomer within the (meth)acrylate monomer (35% or more). This multi-parameter optimization ensures that transparency, adhesion, and mechanical strength are all improved together rather than traded off against each other.
Solution Approach 2:
The composite resin system incorporates hexafunctional (meth)acrylate monomer (b2) at 5 mass% or more of the (meth)acrylate monomer content to enhance crosslinking density and mechanical properties, while bifunctional (meth)acrylate monomer (b1) ensures adequate flow and adhesion. This composite approach achieves both optical and mechanical performance simultaneously.
3Reliability
If the photocurable resin composition includes multiple monomers and additives for improved performance, then the cured film achieves excellent resistance properties, but the composition complexity increases
Solution Approach 1:
The patent establishes specific quantitative ranges for each component to simplify the formulation process: urethane (meth)acrylate (45-75 mass%), (meth)acrylate monomer (20-45 mass%), with bifunctional monomer comprising 35% or more of the (meth)acrylate monomer. These parameter specifications provide clear formulation guidelines that reduce complexity despite the multi-component system.
Solution Approach 2:
The urethane (meth)acrylate (A) serves multiple functions: it acts as the primary resin matrix, provides adhesion to the polycarbonate substrate, contributes to mechanical strength, and ensures proper curing under UV irradiation. This multi-functionality reduces the need for separate additives for each property, simplifying the overall composition.
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 forms a cured film with excellent smoothness, adhesion, transparency, and resistance to abrasion, scratches, cracks, and weathering, preventing clouding even under LED exposure, thus enhancing the durability and appearance of molded articles like head lamp lenses.
Implementation Method 1
a photopolymerization initiator (C)
Implementation Method 2
the inclusion of an ultraviolet absorber and photostabilizer
Implementation Method 3
the inclusion of an ultraviolet absorber and photostabilizer
Data Source
AI summary
An object of the present invention is to provide a photocurable resin composition capable of forming a cured film having an excellent smoothness, adhesion, transparency, abrasion resistance, scratch resistance, crack resistance and weather resistance. [Solution to problem] The photocurable resin composition according to the present invention is a photocurable resin composition including a urethane (meth)acrylate (A), a (meth)acrylate monomer (B), a photopolymerization initiator (C) and a leveling agent (D); wherein the (meth)acrylate monomer (B) includes at least a bifunctional (meth)acrylate monomer (b1) and a hexafunctional (meth)acrylate monomer (b2); wherein the content of the urethane (meth)acrylate (A) is 45% by mass or more and 75% by mass or less with respect to the solid content of the photocurable resin composition; wherein the content of the (meth)acrylate monomer (B) is 20% by mass or more and 45% by mass or less with respect to the solid content of the photocurable resin composition; and wherein the content of the bifunctional (meth)acrylate monomer (b1) is 35°10 by mass or more with respect to the content of the (meth)acrylate monomer (B).