Transparent Adhesive Sheet for Sensor-Safe Planar Heaters
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Solution Overview
Problem
Existing pressure sensitive adhesive compositions for planar heating elements in vehicle detection units are not suitable for cold environments, as they impair the functionality of optical and infrared sensors due to low luminous and diffuse transmittance, and do not maintain adhesive strength under temperature fluctuations.
Innovation Solution
A pressure sensitive adhesive sheet with specific luminous and diffuse transmittance properties and adhesive strength, designed to maintain sensor functionality and reliability under varying temperatures, using an acrylic-based adhesive layer that is active energy ray curable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pressure sensitive adhesive composition is used for planar heating elements, then adhesive strength is achieved, but luminous transmittance and infrared transmittance are impaired, affecting sensor functionality
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive by incorporating specific acrylic-based pressure sensitive adhesive polymers with controlled glass transition temperatures and molecular weights, achieving both high transmittance (>60% in visible and infrared regions) and adequate adhesive strength through parameter optimization
Solution Approach 2:
The patent creates a composite adhesive system combining acrylic-based pressure sensitive adhesive polymer with specific additives and modifiers, forming a multi-component composition that simultaneously provides optical transparency, infrared transmittance, and adhesive properties required for sensor application
2Ease of operation
If a pressure sensitive adhesive is used to attach the planar heating element, then ease of attachment is improved, but adhesive strength deteriorates under temperature fluctuations
Solution Approach 1:
The patent employs an acrylic-based pressure sensitive adhesive with adjustable glass transition temperature that allows the adhesive to dynamically adapt its properties across temperature ranges, maintaining flexibility at low temperatures and stability at high temperatures, thus preserving adhesive strength under temperature fluctuations while keeping application simple
Solution Approach 2:
The patent optimizes adhesive parameters including glass transition temperature (Tg between -50°C to 0°C), molecular weight (100,000 to 1,000,000), and composition ratios to ensure the adhesive maintains adequate strength across the operating temperature range of -40°C to 85°C while remaining easy to apply
3Illumination intensity
If the adhesive layer is made thinner to improve transmittance, then luminous transmittance is improved, but adhesive strength decreases
Solution Approach 1:
The patent changes the adhesive layer parameters by controlling thickness (5μm to 100μm), molecular weight, and crosslinking density to achieve optimal balance where sufficient transmittance is maintained while adequate adhesive strength is preserved through enhanced polymer chain entanglement and interfacial bonding
4Reliability
If the adhesive is optimized for cold environments, then reliability in cold conditions is improved, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes adhesive parameters for cold environment performance by setting glass transition temperature between -50°C to 0°C and controlling molecular weight and composition, achieving reliable adhesive strength from -40°C to 85°C through a relatively simple single-layer structure that can be applied using conventional pressure sensitive adhesive techniques
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 adhesive sheet ensures minimal impact on sensor functionality and maintains strong adhesion to planar heating elements, even under extreme temperature changes, enhancing durability and reliability.
Implementation Method 1
an average value of luminous transmittance of the pressure sensitive adhesive layer in a wavelength region of 380 to 780 nm is 60% or more, an average value of luminous transmittance of the pressure sensitive adhesive layer in a wavelength region of 800 to 1,000 nm is 60% or more
Implementation Method 2
an acrylic-based adhesive layer that is active energy ray curable
Data Source
AI summary
Pressure sensitive adhesive sheet (1) includes a pressure sensitive adhesive layer (11) to be attached to a planar heating element. The average value of luminous transmittance of the pressure sensitive adhesive layer (11) in a wavelength region of 380 to 780 nm is 60% or more. The average value of luminous transmittance of the pressure sensitive adhesive layer (11) in a wavelength region of 800 to 1,000 nm is 60% or more. The adhesive strength for the pressure sensitive adhesive sheet (1) is 10 N/25 mm or more when measured through: preparing a laminate configured such that a polyethylene terephthalate film having a thickness of 100 μm and a soda-lime glass plate having a thickness of 1.1 mm are bonded together via the pressure sensitive adhesive layer (11); subjecting the laminate to 200 cycles of a heat shock test in which −35° C. and 70° C. are each applied for 30 minutes in alternation; and then peeling off a laminate of the polyethylene terephthalate film and the pressure sensitive adhesive layer from the soda-lime glass plate. The pressure sensitive adhesive sheet (1) is suitable for attachment to a planar heating element.