PU sealant (polyurethane sealant) used for sealing solar panels (photovoltaic modules) is currently one of the mainstream high-performance sealing materials in the photovoltaic industry, especially widely used in frameless double glass modules, frame sealing, junction box bonding and other scenarios. Compared to traditional silicone, it has unique advantages in weather resistance, UV resistance, mechanical strength, and deformation resistance.
1、 Core characteristics (photovoltaic specific grade)
Excellent weather resistance and UV resistance
Long term outdoor UV resistance (about 30 times higher than ordinary silicone)
High and low temperature resistance: -40 ℃~120 ℃, long-term stability, no brittle cracking, no flow
Moisture and heat resistance: passed the aging test at 85 ℃/85% RH for 1000 hours
Cold and hot shock resistance: -40 ℃ ↔ Stable performance after 200 cycles at 90 ℃
Mechanics and Sealing Performance
Low water vapor transmission rate: effectively blocks moisture intrusion, protects battery cells and circuits
High elasticity+high strength: with thermal expansion and contraction of components, resistant to fatigue and cracking
Strong adhesion to aluminum frame, glass, TPE/PET backboard, PC junction box, no need for primer
Electrical and Safety
Excellent electrical insulation and flame retardancy (often up to UL 94 V-0)
Low odor, solvent-free, neutral, non corrosive to copper, aluminum, and PC
2、 Main application scenarios
Aluminum frame sealing for photovoltaic modules (most commonly used)
Waterproof, dustproof, and insulation sealing of frames and glass/backboards
Borderless double glass component edge sealing
Double sided glass without aluminum frame, PU adhesive for structure+integrated sealing
Adhesive and sealing of junction box
Strong bonding between junction box and backplate/glass+waterproof insulation
BIPV (Building Integrated Photovoltaics) Sealing
Weather resistant, temperature resistant, UV resistant, suitable for exposed building environments
3、 Type: Single component vs two-component
Single component PU (moisture cured)
Advantages: Ready to use, simple construction (glue gun glue), room temperature moisture curing
Disadvantages: Slow curing (surface drying takes 1-3 hours, complete curing takes 1-3 days)
Suitable for: on-site installation, small batch production, maintenance and adhesive repair
Representative: Silane modified PU (MS adhesive) (low odor, environmentally friendly, stronger weather resistance)
Two-component PU
Advantages: Fast curing (initial curing within 30 minutes to 1 hour, basic curing within 1 to 2 hours), high strength, no glue overflow
Disadvantages: Requires AB glue mixing, specialized equipment, slightly higher cost
Suitable for: component factory production lines, large-scale high-speed production
