What is the glass transition temperature of pressure sensitive adhesive?

The glass transition temperature (Tg) of pressure-sensitive adhesives typically ranges from -70°C to -20°C, depending on their chemical composition and formulation.
1. Definition and Significance of Glass Transition Temperature
The glass transition temperature (Tg) is the temperature at which a polymer material transitions from a glassy state (hard and brittle) to a highly elastic state (soft and tough). For pressure-sensitive adhesives, Tg is a key indicator of their viscoelastic properties and performance:

A Tg that is too low: The molecular chain is too flexible, which may result in increased initial tack and peel strength, but decreased holding strength (long-term adhesion) and even adhesive residue.

A Tg that is too high: The molecular chain becomes more rigid and less flexible, resulting in weakened adhesion to the adherend, lower initial tack and peel strength, but potentially increased holding strength.
2. Pressure-Sensitive Adhesive Glass Transition Temperature Range
Depending on the chemical composition and formulation, the Tg of pressure-sensitive adhesives typically falls within the following range:

Acrylic pressure-sensitive adhesives:
Common Tg range: -50°C to -30°C. Typical monomers: Butyl acrylate (Tg ≈ -55°C), 2-ethylhexyl acrylate (Tg ≈ -70°C).
Formula Adjustment: The Tg can be adjusted by copolymerizing different monomers (e.g., soft and hard monomers). For example, adding methyl methacrylate (Tg ≈ 105°C) can improve cohesion.
Silicone Pressure-Sensitive Adhesives:
Tg Range: Extremely low, down to -120°C.
Features: Maintains adhesion over an extremely wide temperature range (-65°C to 300°C), suitable for low-energy surfaces (e.g., polytetrafluoroethylene).
Specially Formulated Pressure-Sensitive Adhesives:
High-Temperature-Resistant: By introducing high-Tg monomers or crosslinkers, the Tg in the high-temperature range can be raised to 105°C or even higher (e.g., ABC Super Elastic Water-Based Pressure-Sensitive Adhesive).
Dual-Temperature Transition Temperature Systems: Certain pressure-sensitive adhesives utilize block copolymerization or phase separation to create two Tg regions, achieving both high- and low-temperature performance. 3. High-Temperature Protective Film Adhesive KL-26PPAB
KL-26PPAB is a two-component, addition-type liquid silicone rubber adhesive that cures quickly upon heating. After curing, it exhibits excellent adhesion to PET substrates and improves the surface release strength of the silicone rubber.
The adhesive exhibits good flowability before curing; after curing, it exhibits excellent electrical insulation and high transparency, along with excellent surface release strength.
It is suitable for PET silicone protective film products, including mobile phone screen protectors.