UV-Resistant Acrylic Coating on Resin Substrates
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Solution Overview
Problem
Transparent resin substrates, such as polycarbonate, face challenges with weather resistance due to ultraviolet light-induced discoloration, and existing coating solutions require high amounts of ultraviolet light absorbers, leading to increased costs and reduced moldability, with insufficient compatibility between the absorbers and the resin.
Innovation Solution
A resin substrate with a coating layer comprising an acrylic polymer and an ultraviolet light absorbing component, where the acrylic polymer has specific properties like acid value, glass transition point, and molecular weight, and the ultraviolet light absorber has absorption coefficients in the 350-380 nm range, providing improved weather resistance without compromising transparency and fracture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large amount of ultraviolet light absorber is added to the coating layer, then weather resistance is improved, but cost increases and moldability deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the coating layer by specifying precise compositions: acrylic polymer with acid value 1-50 mg KOH/g, glass transition point 60-150°C, and molecular weight 90,000-1,000,000. The ultraviolet light absorber concentration is optimized to 0.1-10 mass%, and the absorption coefficient is controlled at 3.5-100 g/(mg·cm) in the 350-380 nm range. These parameter optimizations achieve sufficient weather resistance while minimizing absorber用量, thereby maintaining moldability and reducing cost.
2Reliability
If a large amount of ultraviolet light absorber is added to the coating layer, then weather resistance is improved, but cost increases
Solution Approach 1:
The patent optimizes the concentration parameter of ultraviolet light absorber to 0.1-10 mass% in the coating layer, which is significantly lower than conventional formulations. This optimized concentration, combined with the high absorption coefficient material selection (3.5-100 g/(mg·cm)), achieves sufficient UV protection while minimizing the quantity of expensive absorber material required, thereby reducing overall coating cost.
3Reliability
If conventional ultraviolet light absorber is used in the coating layer, then weather resistance is partially improved, but the absorber bleeds out from the surface over time due to insufficient compatibility
Solution Approach 1:
The patent uses acrylic polymer as an intermediary matrix material that ensures compatibility with ultraviolet light absorbers. The polymer's controlled properties (acid value 1-50 mg KOH/g, glass transition point 60-150°C, molecular weight 90,000-1,000,000) create an stable environment that prevents absorber migration and bleeding, while still allowing the absorber to function effectively for UV protection.
4Ease of manufacture
If the coating layer uses ultraviolet light absorber with insufficient absorption coefficient, then cost and moldability are maintained, but weather resistance is insufficient
Solution Approach 1:
The patent establishes a minimum absorption coefficient parameter of 3.5 g/(mg·cm) in the 350-380 nm wavelength range for the ultraviolet light absorber material. This parameter threshold ensures that sufficient UV protection is achieved with minimal absorber concentration (0.1-10 mass%), thereby maintaining both weather resistance and moldability. The coating layer thickness is also optimized at 1-100 μm to work synergistically with the high-absorption-coefficient material.
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 solution effectively maintains the resin substrate's transparency and fracture resistance over a long period while offering enhanced weather resistance, reducing the need for high ultraviolet light absorber concentrations and improving compatibility, thus addressing the limitations of existing technologies.
Implementation Method 1
a coating layer containing (1) an acrylic polymer comprising at least one member selected from an alkyl acrylate and an alkyl methacrylate as main monomer units, and (2) an ultraviolet light absorbing component comprising at least one member selected from a polymer having ultraviolet light absorbing groups and an ultraviolet light absorber
Data Source
AI summary
To provide a resin substrate provided with a coating layer having excellent weather resistance and thereby capable of maintaining properties of the resin such as transparency and fracture resistance over a long period of time.A resin substrate provided with a coating layer, which comprises a substrate made of a resin containing an aromatic ring and a coating layer containing an acrylic polymer having an acid value of at most 1 mg KOH/g, a glass transition point of from 60° C. to 150° C. and a mass average molecular weight of from 90,000 to 1,000,000, and an ultraviolet light absorbing component selected from a polymer having ultraviolet light absorbing groups and an ultraviolet light absorber, having an average of absorption coefficients of from 3.5 g/(mg·cm) to 100 g/(mg·cm) to light in a wavelength region of from 350 nm to 380 nm, formed on at least one surface of the substrate.