In the manufacturing of screen protectors—especially tempered glass protectors—AB adhesive plays a crucial role in bonding the protector securely to the screen while maintaining optical transparency. It consists of two primary layers:
A-Side Adhesive: Applied to the back of the glass or PET film. It typically has low initial tack strength (<100g/cm²), enabling "bubble-free self-adhesion" and allowing repositioning during installation.
B-Side Adhesive: The adhesive layer that directly bonds to the device's screen surface.
Why AB glue is important in Screen Protectors
Securely Bonding the Screen and Protector
The primary function of AB adhesive is to firmly attach the screen protector to a display surface (such as a smartphone, tablet, or laptop screen). It must provide strong adhesion to prevent detachment during daily use while maintaining high optical clarity to ensure the display remains vibrant and sharp.
Filling Microscopic Gaps
Even with precise application, small air gaps or surface irregularities can occur between the screen and the protector. High-quality AB adhesive has excellent fluidity and gap-filling properties, which help eliminate trapped air, reduce "rainbow effects," and improve overall visual performance.
Enhancing Durability and Impact Resistance
Once cured, AB adhesive forms a resilient and durable bond, improving the screen protector’s scratch resistance and shock absorption. This reduces the risk of screen fractures by distributing and absorbing impact forces.
Ensuring Compatibility with Curved Screens
Modern smartphones often feature curved-edge displays, requiring an adhesive that is both flexible and strong enough to conform to the screen's shape without lifting or peeling over time. A high-quality AB adhesive ensures seamless adhesion to curved surfaces while maintaining its structural integrity.
How to tell Good AB glue from bad ones？
High Optical Transparency
A premium AB adhesive must have an exceptionally high optical clarity (typically >90% transparency) to ensure no visual distortion. It should remain crystal-clear after curing, without fogging, yellowing, or affecting color accuracy.
Optimal Adhesion Strength
The adhesive should have a balanced adhesion level—strong enough to keep the protector securely in place, yet not excessively tacky to avoid leaving residue or damaging the screen upon removal. Ideally, the adhesion strength should fall within the range of 1-2 N/mm², depending on the application.
Superior Weather Resistance
Screen protectors are often exposed to UV rays, heat, and humidity, so the adhesive must be highly resistant to oxidation and UV degradation. A well-engineered AB adhesive should not yellow, become brittle, or lose adhesion over time.
Low Shrinkage Rate
During curing, adhesives tend to contract. A high-quality AB adhesive should have a shrinkage rate below 1%, minimizing internal stress and preventing warping, peeling, or delamination after installation.
Environmental and Safety Compliance
The best AB adhesives meet strict environmental and safety regulations such as RoHS compliance, ensuring they are non-toxic and odor-free. This is critical for both factory workers and end users, preventing health hazards from harmful chemicals.
