PUR(Moisture-Reactive)Hot Melt Adhesive

LETBOND® PUR Moisture-Reactive Hot Melt Adhesive Series

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Description

The LETBOND® PUP Moisture-Reactive Hot Melt Adhesive series consists of single-component polyurethane (PU) adhesives specifically engineered for 3C product assembly. After application, the material undergoes a cross-linking reaction with moisture from the air and the substrate. Once fully cured, it forms a robust structure that offers superior adhesion, weather resistance, and sealing performance compared to non-reactive alternatives. All products are solvent-free, 100% solid content formulas, combining environmental friendliness with high industrial stability.

Features

  • Single-Component / Solvent-Free / 100% Solids: Safe to use and prevents bubble formation during application.
  • Low Viscosity / Low-Temperature Operation: Can be processed at 90–110°C, making it suitable for precision assembly and micro-nozzle dispensing.
  • High Adhesion: Exhibits excellent bonding to plastics (PC, ABS, PMMA, PA, PP, etc.), metals (stainless steel, aluminum), and glass.
  • Rapid Reaction: Features fast moisture cross-linking; certain models react at approximately twice the speed of standard PUR adhesives.
  • Superior Durability: Once cured, the adhesive provides outstanding waterproof, dustproof, and anti-aging properties.
  • Reworkability: Specific models (e.g., 29258L, 29266B, 29266C) support thermal disassembly and rework within 6 to 24 hours.
  • Extended Versatility: Beyond electronic assembly, it meets diverse requirements for waterproofing, dustproofing, gap filling, and light shielding.

Applications

  • 3C Electronics Assembly: Internal bonding of plastic, metal, and glass components for smartphones and computers.
  • Waterproof and Dustproof Requirements: Ideal for products requiring high-performance seals, such as lens modules and black-frame bonding (29258B).
  • High Weather-Resistance Components: Electronic devices that must operate long-term in environments with varying temperature and humidity.
  • Precision Dispensing: Low-viscosity types (e.g., 29256, 29258L, 29266 series) are optimized for ultra-fine glue path designs.
  • Reworkable Needs: For assemblies requiring disassembly, models 29258L, 29266B, and 29266C allow for component recovery or reuse.
  • Alternative to Traditional Gaskets: Specific models like 29290B (peelable hot melt) can replace O-rings, packing, and gaskets for gap filling while offering eco-friendly disassembly advantages.

Selection Specifications

Model Color Viscosity
(cps / °C ) 		Curing Time
(at 25℃, 65%RH)		 Operating Temp. (°C)
Heating holder / Nozzle
29256
Pale Yellow Solid
3,800 – 25,000 (90–120°C)
Open: 1–2 min / Tack-free: 4 min
Full Cure: 72h
90~110 / 100~120
29258B
Black Paste
2,800 – 9,900 (100–120°C)
Open: 4 min / Tack-free: 20 min
100–110 / 100–115
29258L
Pale Yellow Solid
1,240 – 7,380 (90–120°C)
Open: 4 min / Tack-free: 15 min
Reworkable
90–110 / 100–120
29258
Milky White Paste
3,400 – 24,000 (90–120°C)
Open: 4 min / Tack-free: 1–2 min
Full Cure: 24-72h
Working Temp: -30 to +160°C
90–110 / 90–110
29266B
Black Solid
2,200 – 11,000 (90–120°C)
Open: 4 min / Fast reaction / Reworkable
90–110 / 100–120
29266C
Pale Yellow Solid
2,000 – 13,300 (90–120°C)
Open: 8 min / Reworkable within 24h
90–110 / 100–120
29290B
Black Solid
12,000 – 160,000 (180–200°C)
Peelable / Waterproof & Dustproof / Non-PUR type
180–190 / 180–190

Notes:

  • The values above are for reference only; actual values are based on the Certificate of Analysis (COA) of the shipped batch.