Exceptionally Strong, Durable, Flexible & Adaptable VHB Tapes
VHB Tapes are exceptionally strong bonding tapes, and provide an excellent alternative to mechanical fasteners, screws, rivets, and welds. They work through the bonding tape permanently attaching one substrate to another substrate, and distributes the stress load across the joint. After the materials are joined, the tape creates an exceptional weld.
Action Adhesives VHB Tapes are used in applications such as the following:
- Sign & Display
- Sealed Wood
11 Great Reasons to Choose VHB Tapes From Action Adhesives:
- Spreads Stress across the length of the joints
- Quick and easy to apply and exceptionally clean
- Reduces noise and vibration
- Prevent corrosion by separating different types of materials
- Allow the use of thinner, lighter weight materials
- Clean appearance- They display no unsightly rivets or spot welds
- Vibrant Resistance- The acrylic foam in the tapes distributes the stress over the whole area
- Strength- They displace traditional fasteners such as liquid adhesives, rivets, spot welds and various other fasteners
- Can Cut Easily- They can be cut precisely easily, and are excellent in aiding assembly.
- Exceptionally efficient at absorbing shock
- Resists moisture, UV Light, and temperature cycles
Foamed acrylic tapes are formulated from acrylic copolymers and monomers to produce a self adhesive viscoelastic foam, which is a high density, closed cell foam, cured by using U.V. light. There are no solvents used in the manufacturing process.
The foam is produced by coating on a ‘knife over roller’ coating head. The syrup is then coated onto a high grade polyester process liner. Two process liners are used in the manufacturing, with the gap between the bottom and the top liner determining the thickness of the foam.
The tape is available in thicknesses between 0.25mm (10mil) and 3mm (120mil). Tolerance on the thickness of the foam is ± 50 micron.
VHB acrylic foams are available in White, Grey and Clear grades. The white and grey grades have glass microspheres as a filler that gives exceptional cohesive strength to the foam. The clear grade does not contain microspheres.
The density of the white and grey grades is approximately 800kg/m3 (1348 lb/yd3), and the clear is 1000kg/m3 (1686 lb/yd3).
Standard liners are 135 micron red polyethylene and 120 gsm white PE coated paper.
Application Performance is dependent upon:
- Tape thickness
- Chemical constitution
- Viscoelastic properties (flow characteristics)
- Cell structure
- Foam density
- Ensure that the surfaces to be bonded are completely clean and free from dust and grease
- The surfaces to be bonded should be dry and free from any loose particles
- The best cleaning medium is a solvent such as Isopropyl Alcohol applied with a clean cloth or tissue
- To obtain the optimum bond sufficient pressure should be applied to the surface area to be bonded. To ensure good adhesive ‘wet out’ typical pressure should be 15psi (100kpa)
- The adhesive is pressure sensitive and best results are achieved with maximum surface contact under pressure.
- 50% of the optimum bond strength will be achieved after 20 minutes. 90% after 24 hours and 100% is achieved after 72 hours
- Avoid significant load bearing to the bond directly after application
- Recommended application temperature is +20˚C to +36˚C
- Minimum application temperature should not be below +10˚C
- Certain surfaces will require priming or sealing – such as porous surfaces like plaster and concrete, also absorbent surfaces such as wood and fabric
- Metals with oxidised surfaces such as aluminium, copper and brass may need priming. Low energy surfaces such as polypropylene plastics containing aggressive plasticisers may also need treatment.
VHB bonds to a wide variety of surfaces.
The viscoelastic properties of VHB allows the adhesive to flow into the microscopic surface of materials. The adhesive bond is very strong when there is good ‘wet out’, maximum adhesive contact under pressure with the substrates to be bonded.
Abrading the surface to be bonded actually improves the strength of the bond. This creates a rough surface for a greater area for the adhesive to key into.
The elastic characteristics of the foam give it very good internal cohesive strength to support loads in both static and dynamic shear. It also gives the foam very good peel adhesion strength
The tape is soft and very flexible which means it has great conformability.
The foam also has very good elasticity due to the high internal cohesive strength of the foam.
The tape will radius well, (go around curves).
THICKNESS OF TAPE TO BE USED
THE THICKNESS OF TAPE SELECTED SHOULD DEPEND ON THE FOLLOWING FACTORS:
- The rigidity of the substrates to be bonded.
- The irregular nature of the two surfaces.
- The amount of pressure to be applied to ensure good adhesive ‘wet out’.
- The mismatch of the two surfaces must be less than half the tape thickness to ensure good surface contact under pressure.
- To ensure good adhesive ‘wet out’ a test piece of the substrate that has an uneven surface should be bonded to a clear acrylic under pressure to see what the contact area is.
- Semi-flexible materials such as some PVC materials with a memory need thicker tape to distribute the stress resulting from the material’s memory.
- Choosing the correct thickness of tape will ensure that the ultimate bond will be achieved.
HOW MUCH TAPE TO USE IN AN APPLICATION?
This depends on a number of factors:
- What are the substrates to be bonded?
- What is the load bearing, is it static or dynamic?
- Is the material subjected to exposure to extremes of weather etc.?
- Is there constant force or spasmodic forces affecting the bond?
As a general rule 645mm2 (1 in2) of tape should be used to hold 1kg (2.2 lbs) in a static situation. This will vary from application to application.
There is a safety factor built into this equation. All users should test the tape in their own application thoroughly.
VHB foamed acrylic tape will hold substantial loads, but a safety factor is important in critical structural application
- Different materials have different expansion and contraction coefficients
- Very often different materials are bonded together, glass to aluminium; PVC to steel; copper to abs; all materials react differently to high and low temperatures
- Foamed acrylic tapes can withstand expansion and contraction movements. In shear and tensile situations, up to three times the thickness of the tape
- Once VHB has been bonded in situation and the optimum bond strength has built up (after 72 hours), it can withstand extremes of temperature, and some grades are very resistant to thermal shock, which comes with a very rapid rise or fall in temperature. VHB4025C and VHB4025G are particularly good at resisting these situations
- Tape bonding is flexible and this avoids metal fatigue that will result from expansion and contraction where mechanical fixings such as screws and rivets are used
FREQUENTLY ASKED QUESTIONS
Q. TEMPERATURE RANGE?
- Normal ambient generally no problem
- -40°C (-40°F) to 93°C (200°F) is not a problem (Concern for shock force at low temperatures)
- Generally successful through low temp ovens (up to about 149°C / 300°F) short term minutes / hours
- Some tapes can handle higher temperature
Q. DURABILITY – HOW LONG WILL IT LAST?
Answer: Acrylic is a very durable chemical material
- Accelerated ageing information demonstrates good performance under harsh conditions. (Florida / Arizona testing, about 100% bond strength after 2 years)
Q. HOW MUCH TAPE SHOULD YOU USE?
- Rule of thumb = 1 in² (645mm²) OF TAPE PER 1kg (2.2 lbs) to be supported
- Customer evaluation required
- Customer generally do not know the magnitude of forces – can calculate tape usage if forces known
- Usage based on other applications / common sense
- Customer evaluation required
Q. RESISTANCE TO WATER / HUMIDITY / SOLVENTS?
EXCELLENT WATER / HUMIDITY RESISTANCE
- Foam softens with water – maintains strong bond
- Normal outdoor conditions – OK
- Submersed extended periods – CONCEIVABLY
EXCELLENT SOLVENT RESISTANCE
- Solvents swell adhesives – DO NOT DISSOLVE
- Different solvents swell adhesives in variable time spans
- Solvent submersion – NOT RECOMMENDED
- Solvent splashing, occasional contact – SHOULD BE OKAY
Q. HOW DO YOU REMOVE TAPE?
- Natural cleaner
- MEK or adhesive remover (Auto parts)
- Messy, time consuming, solvent hazard
CUT OFF USING SOAP AS LUBRICANT
- May need to solvent soak residue to clean surfaces
- High temperature above 316°C (600°F) (Hot air gun)
- Cold temperature below -22°C (-8°F), shock off – (dry ice, CO² fire extinguisher)
MOST COMMON PROBLEMS
WRONG TAPE FOR SURFACE
Watch especially for low surface energy plastics and potentially difficult to adhere to paint surfaces
Optimum application temperature is 21°C (70°F) to 38°C (100°F) temperature must be minimum for most PSA’s. At colder temperatures, immediate bond strength is lower and bond build is slower.
High performance adhesives (VHB), are severely affected affected by surface contamination.
Clean all surfaces with 50:50 mix of isopropyl alcohol and water (works on most surfaces, non hazardous).
Oily surfaces clean with heptane or suitable solvent. Best to follow with IPA – water
Surface abrasion can provide improved bond strength to many surfaces, can speed up bond build.
TAPE TOO THIN
Thin tapes cannot make adequate surface contact with rigid materials.
Semi-flexible materials with memory need thicker tape to distribute stress.
TESTED BEFORE BOND BUILDS
Typically full bond is not reached until 72 hours. (50% at 20 minutes, 90% at 24 hours)
Abrasion speeds bond build
Cold temperature delays bond build
Our technical team will be more than happy to answer any question you may have regarding VHB Tapes.