Benefits
Maximum Gap Filling
The 2.3 mm acrylic foam core easily compensates for uneven surfaces and manufacturing tolerances.
Permanent Structural Bonding
Replaces mechanical fasteners and liquid adhesives while providing a clean, seamless appearance.
Excellent Conformability
The viscoelastic foam distributes stress evenly and accommodates differential thermal expansion.
Outstanding Outdoor Durability
Maintains long-term performance under UV exposure, moisture, humidity, and temperature cycling.
Waterproof Sealing
Closed-cell acrylic foam forms an effective barrier against water, dust, and contaminants.
Simplified Manufacturing
Pressure-sensitive bonding requires no drilling, welding, or curing, reducing production time and labor costs.
Technical Specifications
| Property | Specification |
|---|---|
| Product Name | 3M™ VHB™ 4991 |
| Tape Type | Double-Sided Acrylic Foam Tape |
| Foam Color | Gray |
| Adhesive Type | Multi-Purpose Acrylic |
| Foam Type | Conformable Closed-Cell Acrylic Foam |
| Thickness | 2.3 mm (90 mil) |
| Liner | Red Polyethylene (PE) Film |
| Long-Term Temperature Resistance | 93°C (200°F) |
| Short-Term Temperature Resistance | 149°C (300°F) |
| Indoor / Outdoor | Yes |
| UV Resistance | Excellent |
| Moisture Resistance | Excellent |
| Chemical Resistance | Excellent |
| Shelf Life | 24 Months |
| Converting Services | Slitting, Rewinding, Laminating, Die-Cutting, Kiss-Cutting |
Applications
Typical applications include:
- Metal panel bonding
- Panel stiffener attachment
- Truck and trailer body assembly
- Architectural curtain wall systems
- Building façade panels
- Signage and display fabrication
- Appliance manufacturing
- Electronic equipment assembly
- Glass-to-metal bonding
- Composite panel bonding
- HVAC equipment
- Industrial enclosures
- Transportation equipment
- General structural bonding
Compatible Materials
| Excellent Compatibility | Good Compatibility | Testing Recommended |
|---|---|---|
| Aluminum | Painted Metals | Polypropylene (PP) |
| Stainless Steel | ABS | Polyethylene (PE) |
| Galvanized Steel | Acrylic (PMMA) | PTFE |
| Glass | Polycarbonate (PC) | Silicone Rubber |
| Composite Materials | Sealed Wood | Untreated Low Surface Energy Plastics |
Note: 3M™ VHB™ 4991 is optimized for bonding high- and medium-surface-energy materials. Adhesion testing is recommended for low-surface-energy plastics before production.
Industries
- Construction
- Transportation
- Automotive
- Electronics
- Appliance Manufacturing
- Signage & Displays
- Metal Fabrication
- Renewable Energy
- HVAC
- General Industrial Manufacturing
Why Choose 3M™ VHB™ 4991?
3M™ VHB™ 4991 provides the greatest thickness within the 4941 Family, making it ideal for applications requiring excellent gap-filling, vibration damping, and structural strength. Its multi-purpose acrylic adhesive bonds reliably to metals, glass, composites, and engineering plastics while providing long-term weather resistance and sealing performance.
Key advantages include:
- Extra-thick 2.3 mm acrylic foam
- Superior gap-filling capability
- Permanent structural bonding
- Excellent UV and weather resistance
- Waterproof sealing
- High peel and shear strength
- Excellent vibration damping
- Compatible with precision die-cutting
- No curing required
- OEM converting services available
Installation Guide
- Clean bonding surfaces with a 50:50 mixture of isopropyl alcohol (IPA) and water.
- Ensure surfaces are dry and free from grease, oil, or dust.
- Apply the tape with firm, even pressure.
- Avoid repositioning after initial contact.
- Approximately 50% bond strength develops after 20 minutes, 90% after 24 hours, and 100% after 72 hours at room temperature.
- Test adhesion before mass production, especially on difficult substrates.
Storage
Store the tape in its original packaging.
Recommended storage conditions:
- Temperature: 16°C–27°C (60°F–80°F)
- Relative Humidity: 40%–60%
- Store in a cool, dry environment.
- Keep away from direct sunlight.
- Store rolls horizontally whenever possible.
- Follow FIFO (First-In, First-Out) inventory management.
- Shelf life: 24 months.
Frequently Asked Questions (FAQ)
What is 3M™ VHB™ 4991 used for?
It is used for structural bonding in construction, transportation, appliance manufacturing, signage, electronics, and industrial assembly where thick foam and gap filling are required.
How thick is 3M™ VHB™ 4991?
The nominal thickness is 2.3 mm (90 mil).
What materials can it bond?
It bonds aluminum, stainless steel, galvanized steel, glass, acrylic, polycarbonate, ABS, composites, painted metals, and sealed wood.
Can 4991 replace rivets and screws?
Yes. It is engineered to replace many mechanical fasteners while reducing weight, improving aesthetics, and simplifying assembly.
Is it suitable for outdoor use?
Yes. It provides outstanding resistance to UV radiation, moisture, weathering, and temperature cycling.
What is the difference between 4991 and 4941?
- 4991: 2.3 mm (90 mil) thickness, designed for maximum gap filling and uneven surfaces.
- 4941: 1.1 mm (45 mil) thickness, suitable for general structural bonding with thinner bond lines.
Both products belong to the 3M™ VHB™ 4941 Family and use the same multi-purpose acrylic adhesive.
Can 4991 be die-cut?
Yes. The PE liner provides excellent dimensional stability for die-cutting, kiss-cutting, and automated converting. Guangdong Yousan also offers custom converting services.
Downloads
Available upon request:
- 3M™ VHB™ 4991 Technical Data Sheet (TDS)
- Safety Data Sheet (SDS)
- Product Brochure
- Application Guide
- Die-Cutting Capability Guide
Please contact our sales team if you require the latest technical documentation.
