DOWSIL 739 PLASTIC ADHESIVE
Harmonization Code : 3506.91.90.99 | Prepared glues and other prepared adhesives, not elsewhere specified or included; products suitable for use as glues or adhesives, put up for retail sale as glues or adhesives, not exceeding a net weight of 1 kg ; Adhesives based on polymers of headings 3901 to 3913 or on rubber; Other ; Other
Main features
- One-Part Adhesive System
- Flame-Resistant Cured Adhesive
- Non-Flowing Application Control
Product Description
DOWSIL™ 739 Plastic Adhesive is a one-part, non-flowing general-purpose adhesive designed to provide good flame resistance. Available in white, gray, and black, it cures at room temperature without the need for mixing or curing ovens. With high elongation for added stress relief, it can deliver added reliability resulting from lower cured stress in electronic assemblies.
Product Key Features
- One-Part Room Temperature Cure - requires no mixing or ovens for curing[cite: 1501, 1502]. Faster in-line processing can be achieved with optional heat acceleration.
- Flame Resistance - achieves a UL 94 V-1 flammability rating, making it an excellent option for uses requiring added flame resistance.
- Non-Flowing Rheology - maintains its shape upon dispensing, making it ideal for targeted manual or automated needle dispensing.
- Physical Properties - features an extrusion rate of 157 g/min, a specific gravity of 1.4 (cured), and a tack-free time of 75 minutes at 25°C.
- Stress Relief - provides high elongation for added stress relief, contributing to overall component reliability by lowering cured stress.
Applications
This adhesive is suitable for general-purpose bonding and sealing tasks, particularly where flame resistance and stress relief are prioritized.
- Display Assemblies: Suitable for the wedge bonding of CRTs.
- Power Modules: Ideal for the parts fixing of power supply modules.
- General Sealing: Effectively utilized for general sealing applications across various electronic assemblies.
TDS, SDS & Technical Documents
Technical Specifications
General Properties
ColorColor
Gray, black, whiteSpecific GravitySpecific Gravity
1.34Physical Properties
Tack-Free TimeTack-Free Time
75 minutesAdditional Information
One-Part Non-Flowing General Purpose Adhesive
DOWSIL™ 739 Plastic Adhesive
DOWSIL™ 739 Plastic Adhesive is a premium, one-part, general-purpose silicone adhesive sealant available in white, gray, and black. Formulated as a non-flowing thixotropic paste, this ready-to-use moisture-cure system requires no material pre-mixing and cures cleanly at room temperature when exposed to atmospheric moisture. It is engineered with high elongation to deliver added strain relief, and carries a recognized UL 94 V-1 flammability rating for applications requiring superior flame resistance. It establishes durable unprimed adhesion across common structural substrates to improve overall inline manufacturing cycle reliability.
One-part moisture cure 75 min tack-free time No mixing required UL 94 V-1 Flammability
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Typical engineering values only. Performance profiles are developed at ambient conditions without requiring oven cross-linking.
DOWSIL™ 739 Plastic Adhesive
Key Features
- One-part general purpose RTV system optimizes process tracking by eliminating multi-part mixing tasks.
- Thixotropic non-flowing paste rheology provides excellent vertical bead placement without slumping.
- Cures to a tough, elastic rubber with high elongation properties for optimal joint stress relief.
- Underwriters Laboratories (UL) 94 V-1 flammability recognition supports added flame resistance specs.
- Establishes excellent unprimed primerless adhesion to a broad matrix of reactive plastics and metals.
- Stable chemistry safeguards physical and electrical insulation values continuously from -45°C to 200°C.
Processing Summary
Ease of Dispensing: Supplied ready-to-use for automated or manual needle dispense systems, exhibiting a reliable baseline extrusion rate profile of 157 g/minute.
Skin-Over & Tack Windows: Surface working time tracks up to an hour under ambient room parameters before a skin layer sets. Achieves a full tack-free surface in 75 minutes at 25°C.
Cure Depth Tracking: Cross-linking moves from the outer exposed surface inward at roughly 0.25 inches (6.35 mm) per seven days, attaining >90% mechanics within 24 to 72 hours.
Cure Acceleration: Ambient moisture cures eliminate oven operation costs. High-volume cycle throughput can be further boosted using mild heat below 60°C (140°F).
Handling and Application Guidance
Process Notes
Storage and Shelf Life
- Store stock inside original packaging with covers tightly attached below label temperature limits.
- Take strict precautions to block environmental air moisture contact from reaching raw compound.
- Minimize head air space inside packages; purge partially filled drums or pails with dry air or nitrogen.
- Manage warehouse logistics tracking using the explicit "Use Before" date marked on the product label.
Surface Preparation
- Clean and dry joint faces completely, clearing dust, grease, process fluids, and surface scaling.
- Degrease boundaries using Dow OS fluids, naphtha, mineral spirits, or methyl ethyl ketone (MEK).
- Do not clean using acetone or isopropyl alcohol (IPA) alone, as they fail to remove oils well.
- Incorporate fine surface mechanical abrasion whenever possible to maximize clean contact bonding area.
Cure Environment Factors
- Vulcanization requires adequate environmental access to humidity, working ideally between 30% and 80% RH.
- Do not apply paste inside highly confined or fully enclosed layout zones restricted from open air.
- Screen highly plasticized substrates; mobile components can migrate and act as active release agents.
- Before handling or packaging equipped parts, verify a sufficient room temperature rest is scheduled.
Typical Properties
Engineering Data for DOWSIL™ 739
Physical & Cured Mechanical Performance Properties
| Physical Property Parameter | Typical Engineering Value | Condition / Testing Standard Basis |
|---|---|---|
| Appearance / Available Colors | Non-slump paste / White, gray, black | - |
| Extrusion Rate | 157 g/minute | - |
| Tack-Free Time at 25°C | 75 minutes | - |
| Specific Gravity (Cured) | 1.4 | - |
| Agency Flammability Listing | UL 94 V-1 | - |
Adhesion Qualification Performance: Primerless structural hold develops aggressively across reactive metals, ceramics, glass, and selection plastic laminates. To confirm complete line integrity and clean boundary interface pairing, executing lap shear evaluations to verify a 100 percent cohesive failure result is highly recommended.
Applications
Where DOWSIL™ 739 Fits
Power Supply Modules
Perfectly configured across automated printed circuit board sub-assemblies to fix components and reinforce active heavy power blocks.
- Executes rapid, unprimed structural parts fixing.
- Enhances component mechanical reliability and safety.
- Bypasses curing oven capital costs on the assembly line.
Wedge Bonding of CRT
Acts as a durable, highly elastomeric anchor compound specifically optimized for structural deflection wedge component joints.
- High elongation absorbs relative mechanical vibration.
- Lower cured stress increases line reliability.
- Gray, white, and black colors match variant design needs.
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General Sealing Assemblies
Delivers dependable fluid-tight protection for complex industrial enclosure paths, protecting sensitive board groups from harsh climates.
- Non-sag thixotropic paste tracks neatly into grooves.
- Survives splash or intermittent solvent line exposure.
- Protects assemblies against weathering and thermal expansion cycles.
Package & Support
Standard Packaging & Technical Help
Standard Packaging
- Typically packaged in 100 ml syringes, 330 ml cartridges, 1 kg tubs, and pails (18-25 kg).
- Supplied in nominal 0.45, 3.6, 18, and 200 kg (1, 8, 40, and 440 lb) containers net weight.
- Special bladder pack or alternative tube configurations can be evaluated for specific volume scales.
- Ready-to-use design requires no multi-part meter-mix equipment or automated purging cycles.
Technical Help Capabilities
- Assisting engineers with inline process design to bypass curing ovens and cut factory energy footprint costs.
- Evaluating complex substrate configurations to optimize unprimed adhesion metrics over engineering plastic models.
- Configuring automated needle gauge parameters matching specified 157 g/min extrusion rates.
- Advising on texturing or secondary primer treatments when joining specialized non-reactive surfaces.
Technical Guidance
Tips and Troubleshooting
| Issue | Recommended Action |
|---|---|
| Premature surface skinning or bead tearing during secondary adjustments |
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| Incomplete structural cross-linking down through joint core zones |
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| Adhesion tracking breakdown or low lap shear force values over difficult substrates |
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Next Steps
Ready to Qualify DOWSIL™ 739?
Tell us about your performance, design, and manufacturing challenges. Share your specific substrate pairings, joint geometry designs, takt time constraints, and environment parameters. Our global technical support team is prepared to put our silicon-based material expertise and process knowledge to work for your production floor.
