Chemical Resistance Chemical Resistance: Excellent solvent resistance, Chemical Resistance: Resistance to plasticizer migration Application Type Bond 1 Part or 2 Part 1-Part Material Form Tape Substrate Acrylic paint, Ceramic, Glass, Metal, A wide variety of plastics, Polycarbonate, Polyester paint, Polyurethane paint, PVC, Enameled Steel, Nickel Coated ABS, Plasticized Vinyl, Galvanized Steel, Epoxy, Galvanized Steel, PBT, Foam, ABS, Stainless steel, Nickel Coated ABS, Painted Metals Industry Ideal for use in many interior bonding applications, Ideal for use in many exterior bonding applications, Rivets Manufacturer 3M Chemistry Acrylic Cure Method Pressure sensitive Application Temperature (°F) 70 to 100 Color Gray High Temperature Resistance (°C) 110, 75, 90, High, Outstanding durability Low Temperature Resistance (°C) -35, Outstanding durability Volume Resistivity (O) 2.1e14 (ohm-cm) Density (g/cm³) 0.720 Key Specifications UL746C Listings - File MH 17478
Technical Data for 3M 4956
- Chemical Resistance : Relative Solvent Resistance - Excellent solvent resistance
- Chemical Resistance : Plasticizer Resistance - Resistance to plasticizer migration
- Adhesive - Bond
1 Part or 2 Part
- Metal - Stainless steel, Painted Metals
- Steel - Enameled Steel
- Nickel - Nickel Coated ABS
- Galvanized - Galvanized Steel
- Plastic - A wide variety of plastics
- Acrylic (PMMA) - Acrylic paint
- Polyurethane - Polyurethane paint
- Polyvinyl chloride (PVC) - PVC
- Vinyl - Plasticized Vinyl
- ABS - Nickel Coated ABS
- Polyester - Polyester paint
- Polybutylene Terephthalate (PBT) - PBT
- Galvanized Steel
- Other - Paint, High and medium surface energy substrates
- Rivet - Rivets
- Interior - Ideal for use in many interior bonding applications
- Industrial - Other permanent fasteners, Foils, Spot Welds
- Industrial Exterior - Ideal for use in many exterior bonding applications
- Pressure Sensitive (min) - Pressure sensitive
- UL (Underwriters Laboratory), ULC (Underwriters Laboratories of Canada), NFPA (National Fire Protection Association) - UL746C Listings - File MH 17478
Application Temperature (°F) 70 to 100
General Bond Strength (psi) Good Peel Strength (piw) High Shear Strength (psi) High Tensile Strength (psi) High
High Temperature Resistance (°C) 110, 75, 90, High, Outstanding durability Low Temperature Resistance (°C) -35, Outstanding durability Moisture/Humidity Resistance Excellent
Dissipation Factor 0.02450, 0.37400 Test Method Dielectric Strength (V/mil) 360 Test Method Dielectric Constant 2.29, 1.99 Test Method Thermal Conductivity (W/m°K) 0.08 Surface Resistivity (O) 2.7e14 (ohm/sq) Test Method Volume Resistivity (O) 2.1e14 (ohm-cm) Test Method
Flexibility Conformability Modulus (psi) 3e5 (Pa) Test Method
Coefficient of Thermal Expansion (CTE) 180e-6 (m/m/°C) Density (g/cm³) 0.720
Shelf Life Details All 3M™ VHB™ Tapes have a shelf life of 24 months from date of shipment when stored at 40°F to 100°F (4°C to 38°C) and 0-95% relative humidity. The optimum storage conditions are 72°F (22°C) and 50% relative humidity. Performance of tapes is not projected to change even after shelf life expires, however, 3M does suggest that 3M™ VHB™ Tapes are used prior to the shelf life date whenever possible. Shelf Life Temperature (°F) 40 to 100 Shelf Life Type From date of shipment Shelf Life (mon) 24
Best Practices for 3M 4956
Most substrates are best prepared by cleaning with a 50:50 mixture of isopropyl alcohol (IPA*) and water prior to applying 3M™ VHB™ Tapes.
Exceptions to the general procedure that may require additional surface preparation include: Heavy Oils: A degreaser or solvent-based cleaner may be required to remove heavy oil or grease from a surface and should be followed by cleaning with IPA/water.
Abrasion: Abrading a surface, followed by cleaning with IPA/water, can remove heavy dirt or oxidation and can increase surface area to improve adhesion.
Adhesion Promoters: Priming a surface can significantly improve initial and ultimate adhesion to many materials such as plastics and paints.
Porous surfaces: Most porous and fibered materials such as wood, particleboard, concrete, etc. need to be sealed to provide a unified surface.
Unique Materials: Special surface preparation may be needed for glass and glass-like materials, copper and copper containing metals, and plastics or rubber that contain components that migrate (e.g. plasticizers).
Refer to 3M Technical Bulletin “Surface Preparation for 3M™ VHB™ Tape Applications” for additional details and suggestions. (70-0704-8701-5)
*Note: These cleaner solutions contain greater than 250 g/l of volatile organic compounds (VOC). Please consult your local Air Quality Regulations to be sure the cleaner is compliant. When using solvents, be sure to follow the manufacturer’s precautions and directions for use when handling such materials.
Bond strength is dependent upon the amount of adhesive-to-surface contact developed. Firm application pressure develops better adhesive contact and helps improve bond strength. Typically, good surface contact can be attained by applying enough pressure to insure that the tape experiences approximately 15 psi (100 kPa) pressure. Either roller or platen pressure can be used. Note that rigid surfaces may require 2 or 3 times that much pressure to make the tape experience 15 psi.
Ideal application temperature range is 70°F to 100°F (21°C to 38°C). Pressure sensitive adhesives use viscous flow to achieve substrate contact area. Minimum suggested application temperatures:60°F (15°C): 3M™ VHB™ Tapes 4941, 4945 families.
Note: Initial tape application to surfaces at temperatures below these suggested minimums is not recommended because the adhesive becomes too firm to adhere readily. However, once properly applied, low temperature holding is generally satisfactory.
After application, the bond strength will increase as the adhesive flows onto the surface (also referred to as “wet out”). At room temperature approximately 50% of ultimate bond strength will be achieved after 20 minutes, 90% after 24 hours and 100% after 72 hours. This flow is faster at higher temperatures and slower at lower temperatures. Ultimate bond strength can be achieved more quickly (and in some cases bond strength can be increased) by exposure of the bond to elevated temperatures (e.g. 150°F [66°C] for 1 hour). This can provide better adhesive wetout onto the substrates. Abrasion of the surfaces or the use of primers/ adhesion promoters can also have the effect of increasing bond strength and achieving ultimate bond strength more quickly.
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Dielectric Constant Test Methods
|Dielectric Constant||Test Method|
|2.29||At 1 kHz, ASTM D150|
|1.99||At 1MHz, ASTM D150|
Dielectric Strength Test Methods
|Dielectric Strength||Test Method|
|360 V/mil||ASTM D140|
Dissipation Factor Test Methods
|Dissipation Factor||Test Method|
|0.02450||At 1 kHz, ASTM D150|
|0.37400||At 1MHz, ASTM D150|
Surface Resistivity Test Methods
|Surface Resistivity||Test Method|
|2.7e14 (ohm/sq)||ASTM D257|
Volume Resistivity Test Methods
|Volume Resistivity||Test Method|
|2.1e14 (ohm-cm)||ASTM D257|
Modulus Test Methods
|3e5 (Pa)||25°C||Shear Modulus, 1 Hz|