Introduction

PUR Reactive polyurethane Hot Melt Adhesive Hot Melt Glue for  Electrical Applicance

For bonding glass to ABS appliance panels, PUR hot-melt reactive adhesives strike an excellent balance between process efficiency (immediate positioning/short handling) and long-term reliability (resistance to temperature, humidity, and differential expansion). By ensuring the appropriate open time and adhesive thickness, proper surface activation and primer application, a closed adhesive path, and controlled lamination, a stable mass production window can be established.

Application Process

• Melting: Use a dedicated PUR hot melt applicator/tank. These are designed to melt the adhesive at a controlled temperature (typically 100°C - 130°C / 212°F - 266°F; always follow the manufacturer's datasheet) while preventing moisture ingress. 
• Application: The molten adhesive is applied to one surface (usually the ABS part, as it's less sensitive to thermal shock than glass). Common methods are bead application, spraying, or slot coating.
• Assembly: The two parts are joined immediately (within the open time, usually 30-120 seconds).
• Fixturing: The adhesive cools and gains initial handling strength (set time) within seconds to minutes.
• Curing: This is the crucial reactive phase. The adhesive cures by reacting with atmospheric moisture. It develops its final ultimate strength over 24 to 72 hours (depending on relative humidity, temperature, and bond line thickness). A warm, humid environment accelerates curing.

Advantages of PUR

• High Final Strength: Look for high tensile shear strength values on both glass and ABS.
• Good Flexibility & Elongation at Break: This allows the bond to absorb stress without cracking.
• Heat Resistance: Must exceed the appliance's internal operating temperature. > 90°C / 194°F is a common minimum; many grades offer > 120°C / 248°F.
• Low Volatile Content: Important for electrical applications to prevent fogging on nearby glass or lenses and protect sensitive components.
• Thermal Cycling Performance: The datasheet should show good results after thermal cycling tests (e.g., -40°C to +85°C).
• Color: Available in clear, white, or black to match aesthetic requirements.

Application Scenarios (Electrical Appliance)

1. Appliance panels/display windows (glass and ABS front shell/frame),
2. touch panel decorative covers,
3. and window and frame bonding for refrigerators/washing machines/air purifiers.

Common problems may occur and how to avoid them.

• Edge cracks in glass → Use thicker adhesive layer and rounded corners.
• Delamination under humidity → Improve surface treatment and adhesion area.
• Glue overflow → Optimize dispensing volume and design masking areas.
• Bubbles/voids → Preheat substrates, apply even pressure, allow air escape.

FAQ

Q: What is PUR hot melt adhesive?

A: PUR (Reactive Polyurethane) hot melt adhesive is a moisture-curing adhesive that provides both quick handling strength after cooling and long-term durability through chemical crosslinking.

Q: How should PUR adhesives be stored and handled?

A: Store sealed, in a dry and cool place, away from moisture.

Q: Environmental and safety considerations?

A: Solvent-free with very low VOC emissions. Complied with oeko-tex certificate. 

Q: What's the shelf life of PUR hot melt adhesive?

A: usually 6–12 months.