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1. What is a Double Sided Tape ?
Double sided industrial tapes can generally be split into THICK or THIN bonding systems.
Thick bonding systems normally consist of a foam carrier sandwiched between two layers of either a rubber or acrylic adhesive. They are normally greater than 0.25mm in thickness. A foam carrier ensures greater conformability i.e the ability of the product to bond to irregular or textured surfaces. The thickness of the product required largely depends on this degree of irregularity or 'mismatch' between the two substrate surfaces. This is discussed in more detail below.
Thick bonding systems can also be categorised by their bonding strengths. 'Very High Bond' or 'Ultra High Bond' products have a 100% pure acrylic core resulting in exceptionally high cohesive strengths and may be used in the most demanding of external applications.
Standard foam core product variants would typically only be used for internal applications.
Thin Bonding systems may either have:
- a filmic core or carrier made of Polyester, PVC or Polypropylene coated each side with adhesive.
- a tissue carrier impregnated with adhesive both sides.
- no carrier as in the case of 'adhesive transfer' tapes which consist of pure adhesive extruded onto a silicone liner.
Both thick and thin bonding tapes may use either Acrylic or Rubber adhesive systems.
Acrylic Adhesives have the following advantages over rubber systems:
- over time they exhibit a much greater bond strength and therefore can be used for more demanding, permanent bonding applications
- they are stable to UV light exposure, with significantly better ageing characteristics
- they can perform at extremes of temperature
- exhibit significantly more resistance to chemicals
Rubber adhesives offer the following advantages
- initial tacks are typically better than acrylics with the bond being stronger only upon initial application
- generally less expensive than their acrylic counterparts, therefore more suitable for less demanding applications
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2. What are plasticisers and how can they affect adhesive performance ?
Plasticisers are ingredients chemically added to plastic materials to make them more flexible and stretchy. Problems however can occur when trying to bond these products to other substrates using adhesive. Over a period of time (weeks/months) the plasticiser molecules migrate and are absorbed into the adhesive.
The result is that the adhesive itself becomes flexible and stretchy and looses its adhesion. Bond failure can readily occur.
A number of our products are designed specifically for bonding plastics containing plasticisers. They have a chemical composition containing a high resistance to plasticiser migration.
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3. Why is a Tape called 'Pressure Sensitive'
The term pressure sensitive refers to a characteristic of the type of adhesive used, requiring a moderate amount of pressure to create the bond. |
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4. What type of tape is required for my application ?
A number of factors need to be taken into account when correctly specifying either a double or a single sided adhesive tape.
For Example
- What type of surfaces are to be bonded and if plastic which type ?
- Are the surfaces coated or treated ?
- Are the surfaces rough or smooth ?
- Is gap filling required, if so what is the gap size ?
- Will the joint be subject to any load ?
- Is the item to used indoors or outdoors ?
- If indoors will it be near a window ?
- Will any temperature be involved ?
- Will there be any contact with either moisture, chemicals or solvents ?
- In the main menu we have included a section entitled 'Your Adhesive Requirements' . This allow the completion of an on-line checklist of factors associated with your application. The form is then automatically sent to one of our Technical Managers, who will contact you and advise a selection of suitable products.
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5. What thickness of tape is required?
Choose a thickness of tape which is equivalent to double the amount of surface unevenness.
For example if the surface variation between the two substrates is 0.5mm then the tape should be at least 1.0 mm in thickness. |
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6. How should the substrate surfaces be prepared?
The following summarises the procedure. We stock all application products, primers and cleaning solutions.
1. To obtain best results the surfaces should cleaned with an isopropyl alcohol/water mixture or heptane using applicator pads - assume all surfaces are contaminated even if they look clean.
2. Wipe dry.
3. Apply tape. Avoid finger contact with the adhesive surface.
4. Apply pressure to tape using hand roller.
5. Remove liner and exert pressure on the bond area using the hand roller.
It should be noted that some substrates may need to be 'primed' or 'sealed' prior to bonding
- most porous(e.g concrete) or fibred materials (e.g wood) will require sealing to provide a unified surface.
- some materials (e.g copper,brass,plasicized vinyl) may require priming or coating to prevent interaction between the adhesive and the substrate.
- bonding to glass in a high humidity environment also require the use of an appropriate primer |
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7. What is the ideal application temperature?
The ideal application temperature range is room temperature at or around 21 degrees C. We do however have a range of high bond double sided tape products designed for low application temperature bonding down to 0 degrees centigrade.
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8. What product coverage is required when bonding a double sided tape ?
For outdoor and critical Interior applications use 60 square centimetres of tape per kilogramme of suspended product.
For non-critical Interior applications use 25 square centimetres of tape per kilogramme of suspended product.
For a typical standard foam tape used for non-critical interior applications use 100 square centimetres per 1 kilogramme of weight
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9. How Quickly will full bond strength result with an acrylic adhesive?
After the application, the bond strength will increase as the adhesive migrates into the surface of the substrate.
- at room temperature approximately 50 % of the ultimate strength will be achieved after 20 minutes.
- 90 % after 24 hours
- 100 % after 72 hours
In some cases bond strength can be increased more quickly by exposure of the bond to higher temperatures ie 70 degrees C for 1 hour
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10. How should joints be designed to facilitate the use of Double Sided Tapes ?
Tensile
Forces perpendicular to the joint plane. Stress is equal over the entire bonded area. All the adhesive contributes to the bonded area.
Shear
Forces parallel to the joint plane. As with tensile, stress is uniform over the entire bonded area.
Cleavage
Forces concentrated at the edge of the adhesive joint. Not all of the adhesive in the joint is contributing to the strength at one time.
Peel
Forces confined to the edge of the bond. Usually at least one surface is flexible. Even less adhesive contributes to bond strength than in 'Cleavage'
Therefore should try to maximise:
TENSILE or PEEL forces
Minimise or eliminate CLEAVAGE and PEEL forces |
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11. What surfaces are easy or difficult to bond to?
Examples of easy to bond ( or high surface energy materials) include:
- Metal
- Paper
- Cardboard
- Sealed Wood
- Acrylic Paint
- Acrylic Glass
- Unplasticised PVC
- A.B.S Plastic
Difficult to Bond to Surfaces (low surface energy surfaces) Include:
- Polyethylene
- Polypropylene
- Nylon
- Powder Coated metals
- Special Coated or Treated Papers
Not recommended Surfaces
- Silicone Rubber
- Teflon
Surfaces Requiring Caution
- Injection Moulded Plastics
- Plasticised Vinyl
- Rubber Mixtures
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