Application and Technical Analysis of Near Infrared Transparent Polymer Materials such as PC, PMMA, ABS

[Ⅰ] Definition of Infrared-Transparent Polymer Materials

Infrared-transparent polymer materials – Raw material pellets – 25Kg/bag

NIR-transparent polymer material pellets and profiles

Transmittance spectrum of FLIERMOUSE NIR PMMA M95 series (specific grade)

【I】Core Definitions and Classification of Near Infrared Transparent Plastic Materials

Definition

  • Functional Characteristics: Transmittance >90% in specific infrared bands (NIR/MIR/FIR) while blocking visible/UV light (e.g., NIR materials block 99% UV). Predominantly black in appearance.
  • Classification Criteria:Band Wavelength RangeTypical Materials Applications Near-Infrared 780~1650 nm PC, PMMA, ABS, PET Consumer electronics, Automotive, Security Mid-Infrared 2000~5000 nm COP Medical devices (experimental) Far-Infrared 7000~14000 nm PTFE Military, Aerospace Ultra-Long Wave 1 mm~100 m Electromagnetic wave materialsCommunications, Radar

【II】Near-Infrared (NIR) Transparent Plastics: Comparative Selection Guide

MaterialTypical GradeAdvantagesDisadvantagesKey Applications
NIR PCC92 SeriesHigh impact resistance (drop-proof), HDT 137°CLow surface hardness, scratch-prone, transmittance <94%LiDAR windows, security camera filters
NIR PMMAM95 SeriesHighest transmittance (94%), weather resistanceBrittle, low thermal stability (HDT ≈90°C)Optical lenses, medical endoscopes
NIR ABSA90 SeriesLow density (1.04–1.06 g/cm³), easy processingInferior thermal/chemical resistance vs. PC/PMMALarge appliance housings, robot navigation modules
NIR PETChemical resistance, low costCrystallinity-induced uneven transmittanceSensor windows, optical packaging

【III】Developments in Mid- and Far-Infrared Materials

Mid-Infrared (2000–5000 nm)

  • COP (Cyclo Olefin Polymer): Low birefringence, cryogenic resistance (-100°C), used in missile IR windows and astronaut visors.

Far-Infrared (7000–14000 nm)

  • PTFE (Polytetrafluoroethylene): Stable broadband transmittance, challenging processing (sintering required).

【IV】Key R&D and Testing Technologies

Core Technical Pathways

  1. Molecular Structure Modulation:
    • Side-chain modification: Adjust ester group ratios in PC to reduce C-H bond IR absorption peaks.
    • Additive formulation: Nano-ZnSe (enhances MIR transmittance) or SiO₂ (improves abrasion resistance).
  2. Band Customization:
    • Case study: Suppress 1400–1500 nm water absorption peaks to align with 1550 nm LiDAR wavelengths.
  3. Performance Balancing:
    • Incorporate benzotriazole UV absorbers while maintaining >90% IR transmittance.

Testing Equipment List

Test ItemEquipmentKey Parameters
IR TransmittanceFTIR SpectrometerWavelength resolution ≤4 cm⁻¹
Mechanical PropertiesUniversal Tensile Tester, Izod Impact TesterTensile speed: 5 mm/min
Thermal StabilityHeat Deflection Temperature (HDT) TesterLoad: 1.82 MPa
FlammabilityUL-94 Combustion TesterVertical burn rating (V0/V1/V2)

【V】Core Application Scenarios and Case Studies

Autonomous Driving & Automotive Industry

  • ADAS LiDAR Window:
    • Material: NIR PMMA M95-1073J (94% transmittance, 105°C heat resistance).
    • Validation: Passes 85°C/85% RH dual-85 test, SAE J400 gravel impact resistance.

Security & Surveillance

  • Covert IR Illumination Filter:
    • Material: Black NIR PC C92-1073 (>99% visible light blocking, 93% transmittance @850 nm).

Medical Sterilization Devices

  • Endoscope Sleeve:
    • Material: COC (γ-ray sterilization resistance, >90% transmittance @3–5 μm).

【VI】Injection Molding Full-Process Specifications

Mold Design Requirements

ParameterSpecificationImpact
Optical precision (Rt)<0.5 μmLight path deviation
Surface roughness (Ra)<0.01 μmReduces diffuse reflection (>5%)
Mold lifespan>380,000 cyclesPrevents optical surface wear

Injection Machine & Screw Selection

MaterialScrew TypeL/D RatioCompression RatioMachine Type
NIR PC C92Gradual compression (40–50% zone)15–202–3Electric precision press
NIR PMMA M95Gradual compression (≥50% zone)15–202–3Electric precision press
NIR ABS A90Gradual compression (20–30% zone)15–202–3Electric precision press

Process Parameters

MaterialDrying ConditionsMold TemperatureMelt TemperatureCritical Notes
NIR PC C92120°C, 3–6h80–120°C (heated)260–300°CAvoid multi-stage injection (prevents molecular orientation imbalance)
NIR PMMA M9580–95°C, 3–4h50–65°C200–240°CPacking pressure ≤80% (prevents stress cracking)
NIR ABS A9090°C, 2–4hAmbient cooling180–220°CMold temp >40°C causes shrinkage fluctuation

【VII】Future Trends and Challenges

  1. Metamaterial Structures: Biomimetic moth-eye nanostructures (period <1 μm) for broadband transmittance enhancement (+5–8%).
  2. Hybrid Materials: PC/PMMA blends (with compatibilizers) balancing hardness and transmittance.
  3. Eco-Friendly Upgrades: Halogen-free flame-retardant NIR ABS (UL94 V0 certification).

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