Aromatic Polycarbonate Composition for Stable IR Sensor Filtering
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Solution Overview
Problem
Existing polycarbonate resins used in infrared sensing systems for autonomous driving lack thermal stability and photostability, particularly when exposed to sunlight, and do not effectively cut noise from visible to near-infrared wavelengths, which is crucial for advanced sensing accuracy.
Innovation Solution
An aromatic polycarbonate resin composition containing specific colorants and thermal stabilizers, with defined weight ratios and absorption maxima, achieving low light transmittance and stability in molded articles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polycarbonate resins with high fluidity (viscosity average molecular weight of 24,000 or less) are used to achieve easy molding at high temperature, then ease of manufacture is improved, but thermal stability of absorption properties deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the resin by incorporating specific stabilizer packages (phosphite compounds, hindered phenols, sulfur compounds) in controlled amounts to maintain thermal stability while using lower molecular weight polycarbonate for ease of molding
Solution Approach 2:
The patent creates a composite resin system combining polycarbonate base resin with multiple stabilizer components (phosphite, phenol, sulfur compounds) and colorants to achieve both processability and thermal stability of optical properties
2Ease of manufacture
If molding temperature is increased to 300-340°C to achieve high fluidity for thin section molding, then ease of manufacture is improved, but thermal stability of absorption properties deteriorates
Solution Approach 1:
The patent applies stabilizers beforehand to the resin system before molding to prevent thermal degradation during the high-temperature molding process, ensuring absorption properties remain stable despite the harsh processing conditions
Solution Approach 2:
The patent modifies the chemical environment of the resin by adding specific stabilizer compounds that raise the effective processing temperature window, allowing high-temperature molding without compromising the thermal stability of the colorants
3Measurement precision
If wavelength-selective colorants are added to achieve noise cutting from visible to near-infrared, then measurement precision is improved, but photostability of absorption properties deteriorates
Solution Approach 1:
The patent introduces UV absorbers and hindered phenols as intermediary substances that absorb harmful UV radiation and free radicals, protecting the wavelength-selective colorants from photodegradation while maintaining their optical filtering function
Solution Approach 2:
The patent creates a composite colorant system combining wavelength-selective pigments with photostabilizers (UV absorbers, hindered phenols) to achieve both noise filtering capability and long-term photostability in the automotive environment
4Ease of operation
If resin thickness is reduced to 1-3 mm to achieve compact sensor integration, then ease of operation is improved, but thermal stability of absorption properties deteriorates
Solution Approach 1:
The patent changes the resin composition parameters to include stabilizers that maintain absorption property stability independent of thickness, allowing thin-section molding while preserving thermal stability of optical 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 resin composition ensures thermal stability, moisture resistance, and photostability, providing wavelength-selective absorption properties suitable for infrared sensors, enhancing sensing accuracy and durability in automotive environments.
Implementation Method 1
a colorant having an absorption maximum at 870 nm or more and less than 1,000 nm
Implementation Method 2
a phosphorus-based thermal stabilizer and/or a phenol-based thermal stabilizer
Implementation Method 3
excellent in thermal stability and moisture and heat resistance
Implementation Method 4
excellent in thermal stability and moisture and heat resistance
Implementation Method 5
allows for transmission in the wavelength range used for sensing and cuts transmission in a lower wavelength range
Data Source
AI summary
The invention provides an aromatic polycarbonate resin composition that is excellent in thermal stability and moisture and heat resistance, and makes a molded article that has wavelength-selective absorption properties and is further excellent in the thermal stability and photostability of absorption properties, and also a molded article thereof.The invention is a resin composition including, per (A) 100 parts by weight of an aromatic polycarbonate resin (component A), (B) 0.03 to 1.2 parts by weight of a colorant having an absorption maximum at less than 650 nm (component B), (C) 0.001 to 0.3 parts by weight of a colorant having an absorption maximum at 650 nm or more and less than 870 nm (component C), (D) 0.001 to 0.3 parts by weight of a colorant having an absorption maximum at 870 nm or more and less than 1,000 nm (component D), and (E) 0.003 to 0.5 parts by weight of a phosphorus-based thermal stabilizer and/or a phenol-based thermal stabilizer (component E), the resin composition being configured such that an average value of through-thickness light transmittance of a 3-mm-thick molded article thereof at 400 nm to 870 nm is 1.5% or less.