Index Modified Polymer Coating for Scratch and UV Resistance
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Solution Overview
Problem
Polycarbonate components in the automotive industry face issues with scratching and degradation from UV light, with existing coatings being either costly or having short lifespans due to UV blocking layer degradation.
Innovation Solution
A multilayer or single gradient protective coating is formed using pulse modulation techniques in microwave plasma chemical vapor deposition (MPCVD), combining organic and inorganic materials with interleaved layers, providing scratch resistance and UV absorption while matching the refractive index to the polymer substrate, and using precursor gases like hexamethyldisiloxane, diethylzinc, and ammonia to control radical density and composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lacquer based coating is sprayed on polycarbonate and thermally cured to provide a hard coating that blocks UV light, then scratch resistance and UV blocking are improved, but the cost becomes excessively high
Solution Approach 1:
The patent changes the deposition parameters by using microwave plasma CVD instead of conventional thermal curing, allowing the coating to be formed at lower temperatures (below 200°C) while achieving comparable or superior hardness and UV blocking properties at reduced cost
Solution Approach 2:
The patent replaces the thermal curing process with a plasma-enhanced chemical vapor deposition process, substituting thermal energy with microwave plasma energy to achieve coating formation at lower temperatures and reduced cost
2Reliability
If a soft UV blocking layer benzyl phenon is formed on polycarbonate substrate followed by a hard organo-silicon coating by PECVD, then scratch resistance is improved, but the UV blocking layer degrades from UV light attack over time causing the coating to shrink or crack
Solution Approach 1:
The patent creates a composite coating system combining organo-silicon polymers with inorganic UV absorbers (such as zinc oxide, titanium dioxide, or cerium oxide) where the inorganic components provide stable UV blocking that does not degrade over time, while the organo-silicon provides hardness and scratch resistance
Solution Approach 2:
The patent introduces an inorganic UV absorber layer as an intermediary between the organo-silicon coating and the polycarbonate substrate, where the inorganic layer absorbs UV light and protects the underlying substrate and coating from UV degradation, while the organo-silicon layer provides mechanical hardness
3Reliability
If a protective coating is applied to provide scratch resistance and UV absorption, then protection against scratching and UV degradation is improved, but the coating may reduce transparency
Solution Approach 1:
The patent optimizes the coating thickness parameter to be in the range of 1-10 micrometers, which is sufficient to provide scratch resistance and UV blocking while maintaining optical transparency, avoiding excessive thickness that would cause haze or light distortion
Solution Approach 2:
The patent creates a gradient coating structure where the composition and thickness vary through the coating depth, with the top layer optimized for optical clarity and the bottom layer providing enhanced UV blocking and mechanical protection, allowing different regions of the coating to have different functional properties
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 coating achieves long-lasting scratch resistance and UV absorption with improved adhesion and reduced thermal load, maintaining transparency and effectiveness over time, addressing the limitations of existing coatings.
Implementation Method 1
microwave plasma chemical vapor deposition (MPCVD)
Implementation Method 2
microwave plasma chemical vapor deposition (MPCVD)
Implementation Method 3
pulse modulation techniques in a microwave plasma chemical vapor deposition (MPCVD) process
Implementation Method 4
UV light absorption
Implementation Method 5
provides scratch resistance
Data Source
AI summary
The invention includes the structure of a multilayer protective coating, which may have, among other properties, scratch resistance, UV absorption, and an effective refractive index matched to a polymer substrate such as polycarbonate. Each layer may contain multiple components consisting of organic and inorganic materials. The multilayer protective coating includes interleaved organic layers and inorganic layers. The organic layers may have 20% or more organic compounds such as SiOxCyHz. The inorganic layers may have 80% or more inorganic materials, such as SiO2, SiOxNy, and ZnO, or mixtures thereof. Each layer of the multilayer protective coating is a micro layer and may have a thickness of 5 angstroms or less in various embodiments. The multilayer protective coating may contain in the order of hundreds or thousands of micro layers, depending upon the design requirement of applications. In each micro layer, the components may have substantially continuous variations in concentration.