In the field of smartphones, automotive displays and optical sensors, optically clear adhesive for glass/metal is the core material for achieving seamless bonding and visual integrity. This type of adhesive must have ultra-high light transmittance (>95%), environmental aging resistance and low-stress bonding properties to meet the stringent requirements of precision optical devices and metal substrates. This article will deeply analyze its technical challenges and innovative solutions, and focus on the breakthrough application of U-Sunny's T-7333 polyurethane acrylate resin in the field of transparent bonding.
1. Core performance requirements of optically transparent adhesive
The bonding of heterogeneous materials between glass and metal poses multiple challenges to adhesives:
Optical performance: The transmittance needs to match that of glass (>95%), and there should be no yellowing or haze after curing;
Interface stress control: The thermal expansion coefficient needs to be close to that of the substrate to avoid delamination or cracking caused by temperature difference;
Durability: Resistant to ultraviolet rays, humidity, heat and chemical corrosion (such as sweat and detergents) to ensure long-term reliability.
Studies have shown that traditional epoxy resins have a high risk of yellowing, while acrylic adhesives achieve a balance between rapid prototyping and optical performance through UV curing technology, becoming the mainstream choice.
2. Technological breakthroughs of U-Sunny T-7333 resin
In response to the demand for high light transmittance and durability, U-Sunny's T-7333 resin sets an industry benchmark through three major innovations:
Ultra-transparent and non-yellowing: The film transmittance reaches 98% (ASTM D1003 standard), and the yellowing index ΔY<1.5 after 1000 hours of UV aging test, which is suitable for AMOLED screen packaging;
Low shrinkage stress (<0.3%): The polyurethane acrylate system reduces curing shrinkage, and there is no Newton ring or rainbow pattern when bonding Corning Gorilla Glass;
Weather resistance upgrade: Withstands -50℃~150℃ temperature difference cycle, and the moisture and heat resistance (85℃/85%RH) has passed 3000 hours of testing.
Experimental data shows that the initial bonding strength of T-7333 reaches 20N/25mm, and the strength retention rate after cold and hot shock is >90%, which is far superior to silicone and epoxy resin.
3. Application cases of transparent bonding in multiple fields
Consumer electronics:
Used for metal-glass bonding in the hinge area of folding screen mobile phones, no delamination after bending 100,000 times;
As encapsulation adhesive for optical waveguide modules of AR glasses, the refractive index matching accuracy reaches ±0.002.
Automotive industry:
Bond HUD (head-up display) glass and aluminum alloy frame to withstand high temperature vibration in the engine compartment;
Used for encapsulation of vehicle-mounted camera lens group, passed IP6K9K waterproof and dustproof certification.
Optical devices:
As UV-cured coating for optical filters to reduce light path scattering loss;
Adapted to medical endoscope body bonding, passed ISO 10993 biocompatibility test.
4. Industry Trends and Technological Innovation
With the popularity of flexible electronics and micro-optical devices, U-Sunny continues to optimize T-7333 resin:
Ultra-thin coating process: supports 1~5μm ultra-thin adhesive layer coating, adapted to Micro LED mass transfer technology;
Environmental upgrade: develop bio-based monomer formula, biocarbon content increased to 35%, reducing carbon footprint;
Intelligent detection: integrated AI visual system to monitor adhesive layer bubbles and thickness uniformity in real time.
The technological evolution of optically clear adhesive for glass/metal is pushing the boundaries of the display and optical industries. U-Sunny T-7333 resin has become the preferred solution in the field of glass/metal bonding due to its ultra-high light transmittance, ultra-low stress and extreme environmental tolerance. If you need an optical performance test report or customized formula, please contact our technical team.