Primer Composition with Layered UV Protection for Durable Resin Coatings
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Solution Overview
Problem
Existing coatings for organic resin substrates, such as polycarbonate, fail to provide adequate abrasion resistance, adhesion, and weather resistance, especially when exposed to outdoor conditions for extended periods, leading to issues like peeling, cracking, and clouding.
Innovation Solution
A primer composition comprising specific copolymers, ultraviolet absorbers, inorganic particles, and a silicone hardcoat layer, which includes a vinyl copolymer without alkoxysilyl groups and a glass transition point of 80°C or higher, along with a cyclic hindered amine structure and controlled solvent content, to enhance adhesion and weather resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a large amount of ultraviolet absorber is added to the undercoat layer, then UV-shielding properties are improved, but adherence to substrate and silicone hardcoat layer deteriorates and crack formation occurs
Solution Approach 1:
The patent divides the ultraviolet absorption function into two separate layers: the undercoat layer contains a copolymer with chemically attached ultraviolet absorbers for primary UV shielding, while the silicone hardcoat layer contains additional ultraviolet absorbers for secondary UV protection. This segmentation allows each layer to be optimized independently, preventing the adherence and crack resistance problems that occur when excessive ultraviolet absorbers are concentrated in a single layer.
Solution Approach 2:
The undercoat layer uses a copolymer composed of a vinyl monomer with an ultraviolet absorber chemically attached on the side chain and a copolymerizable vinyl monomer. This composite material structure ensures the ultraviolet absorber is firmly bonded to the polymer backbone, preventing migration and degradation while maintaining excellent adherence to both the substrate and the overlying silicone hardcoat layer.
2Object-affected harmful factors
If a large amount of ultraviolet absorber is added to the silicone hardcoat layer, then UV-shielding properties are improved, but abrasion resistance deteriorates
Solution Approach 1:
The patent segments the ultraviolet protection function between two layers, placing only a moderate amount of ultraviolet absorbers in the silicone hardcoat layer (0.1-10 parts by weight per 100 parts by weight of silicone resin). The primary UV shielding burden is placed on the undercoat layer, allowing the hardcoat layer to maintain its abrasion resistance while still providing UV protection.
Solution Approach 2:
Different regions of the coating system are assigned different functional qualities: the undercoat layer is optimized for UV absorption with its copolymer containing chemically attached ultraviolet absorbers, while the silicone hardcoat layer is optimized for abrasion resistance with crosslinked silicone resin, containing only sufficient ultraviolet absorbers to provide supplementary UV protection without compromising hardness.
3Illumination intensity
If conventional coating methods are used on polycarbonate resin, then transparency is maintained, but abrasion resistance and weather resistance are inferior to glass
Solution Approach 1:
The patent employs a composite coating system consisting of an undercoat layer with ultraviolet-absorbing copolymer and a silicone hardcoat layer with crosslinked silicone resin. This multi-layer composite structure provides both the transparency needed for optical applications and the enhanced abrasion and weather resistance required for long-term outdoor durability, surpassing the performance of single-layer conventional coatings.
Solution Approach 2:
The patent changes key parameters of the coating system: the undercoat layer uses a copolymer with specifically designed molecular structure containing chemically attached ultraviolet absorbers, and the hardcoat layer uses silicone resin with controlled crosslinking density. These parameter changes enable the coating to simultaneously achieve high transparency, excellent abrasion resistance, and superior weather resistance.
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 primer composition, combined with a silicone hardcoat layer, achieves excellent abrasion resistance, adhesion, and weather resistance, maintaining visible-light transmittance, suitable for long-term outdoor use in applications like vehicle windows and noise barriers.
Implementation Method 1
a primer composition containing: (A) a total of 100 parts by weight of components (A-1) and (A-2) below in a weight ratio (A-1):(A-2) of from 3:1 to 1:3 (A-1) a copolymer which includes constitutional units (a) of formula (1) below and constitutional units (b) of formula (2) below, and does not include hydroxyphenyltriazne structures, benzophenone structures and benzotriazole structures
Implementation Method 2
a primer composition containing: (D) 3 to 20 parts by weight of inorganic particles having a median diameter as measured by the dynamic light scattering method of 100 nm or less
Implementation Method 3
a copolymer which includes constitutional units (a) of formula (1) below and constitutional units (b) of formula (2) below
Implementation Method 4
a copolymer which includes constitutional units (a) of formula (1) below and constitutional units (b) of formula (2) below
Data Source
AI summary
Provided is a primer composition that contains:(A) a copolymer (A-1) which contains a constituent unit represented by the formula shown below and which does not contain a prescribed ultraviolet radiation-absorbing group(R1 denotes a hydrogen atom or the like, R2 denotes a monovalent hydrocarbon group or the like, R4 denotes a hydrogen atom or the like, R5 and R6 each denote an alkyl group or the like. X2 denotes an alkyleneoxycarbonyl group or the like, n denotes an integer between 1 and 3, and * denotes a bond to an adjacent constituent unit);a vinyl-based (co)polymer (A-2) which does not contain an alkoxysilyl, does not contain a prescribed ultraviolet radiation-absorbing group, and has a glass transition point of 80° C. or higher;an ultraviolet radiation absorber (B);a compound (C) having a cyclic hindered amine structure;inorganic particles (D) having a median diameter of 100 nm or less; anda solvent (E). The (A-1):(A-2) mass ratio is 3:1 to 1:3.