Organo Polysiloxane Hard Coating for Resin Substrate Bending
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Solution Overview
Problem
Transparent resin plates, such as polycarbonate, face challenges with abrasion resistance, weather resistance, and mechanical stress when used as window materials in vehicles and building applications, particularly when bent or subjected to thermal stress, leading to cracking and delamination of the hard coating layer.
Innovation Solution
A hard coating composition comprising organo polysiloxanes with specific silicon-containing bond units, produced through hydrolytic condensation reactions, is applied to the resin substrate to enhance abrasion resistance, weather resistance, and cracking resistance, allowing the coated resin to maintain transparency and mechanical integrity even in bent states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silicone type hard coating layer is formed on a transparent resin plate to improve abrasion resistance and weather resistance, then the coating layer provides protective properties, but the coating layer is sensitive to thermal stress and bending stress, causing cracks to form after cooling a formed product to ordinary temperature
Solution Approach 1:
The patent applies parameter changes by controlling the molecular weight distribution of the organopolysiloxane, specifically maintaining a weight average molecular weight of 2,000-10,000 and a polydispersity index of 1.05-2.0. This optimization of molecular parameters enables the coating layer to achieve both high abrasion resistance and sufficient flexibility to withstand thermal and bending stresses without cracking.
Solution Approach 2:
The patent uses composite materials by formulating a hard coating composition that combines organopolysiloxane with specific molecular weight characteristics with other coating components. This composite approach creates a coating layer that integrates the hardness and weather resistance of silicone with improved mechanical flexibility to prevent cracking under stress.
2Reliability
If the hard coating layer is applied to enhance weather resistance, then the coating provides durability against environmental factors, but the coating layer lacks resistance against forcible bending at ordinary temperature, leading to delamination and deterioration of mechanical strength
Solution Approach 1:
The patent achieves the balance between weather resistance and bending flexibility by precisely controlling the molecular weight parameters of the organopolysiloxane. The weight average molecular weight of 2,000-10,000 and polydispersity index of 1.05-2.0 create a molecular structure that is sufficiently crosslinked for weather resistance yet flexible enough to accommodate cold forming and bent state applications without delamination.
3Ease of operation
If a resin substrate is forcibly bent at ordinary temperature by cold forming, then the resin can be shaped for various applications, but the hard coating layer cracks or the resin substrate forms gathering of fine cracks (crazing), reducing transparency and mechanical strength
Solution Approach 1:
The patent resolves the contradiction between cold formability and maintaining transparency without crazing by optimizing the molecular weight parameters of the organopolysiloxane. The controlled weight average molecular weight (2,000-10,000) and polydispersity index (1.05-2.0) create a coating layer with appropriate viscoelastic properties that can flex during cold forming without cracking, thereby maintaining transparency and preventing crazing in the resin substrate.
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 hard coating composition significantly improves the resin substrate's resistance to abrasion, weathering, and mechanical stress, preventing cracking and delamination, while maintaining transparency and durability, even when the resin is forcibly bent or exposed to thermal stress.
Implementation Method 1
an organo polysiloxane having silicon-containing bond units represented by the following formulae T1 to T3, produced by subjecting a hydrolyzable silane compound to a hydrolytic condensation reaction
Data Source
Figure 1
AI summary
To provide an organo polysiloxane which is capable of improving the abrasion resistance and weather resistance of a hard coating layer obtained by using a silicone-type hard coating composition; a hard coating composition which is capable of forming, on a resin substrate surface, a hard coating layer excellent in the abrasion resistance and weather resistance; a resin substrate having a hard coating layer excellent in the abrasion resistance and weather resistance; and a resin substrate having a hard coating layer which can be used in a bent state. A hard coating composition comprising two types of an organo polysiloxane (a) composed mainly of T units as silicone-containing bond units and the same (b), i.e. (a) is an organo polysiloxane having 3 types of T units in a specific ratio, and (b) is an organo polysiloxane having a weight average molecular weight from 1/10 to 1/1.5 time that of (a). Such an organo polysiloxane (a). Further, a resin substrate having a hard coating layer made of a cured product of such a composition.