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Site Admin
Joined: 24 Jan 2006
Posts: 151
Location: Montreal
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Application Techniques
For successful application Transfert Tapes it is important to have clean and dry surfaces, to provide adequate pressure to make contact with the substrates, and to insure application temperature is sufficient to build adhesion. Transfert Tapes will build adhesion with time. Adhesion promoters can be used to increase adhesion, to speed bond build or to improve durability on select materials.
Clean
Most substrates are best prepared by cleaning with a 50:50 mixture of isopropyl alcohol (IPA)* and water prior to applying Transfert 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).
* 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.
Pressure
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.
Temperature
Ideal application temperature range is 70ºF to 100ºF (21ºC to 38ºC). Pressure sensitive adhesives use viscous flow to achieve substrate contact area. Minimum suggested application temperatures:
50ºF (10ºC): 4950, 5952, 4910, 4952, 4611, 4622 tape families
60ºF (15ºC): 4941, 4945 tape families
32ºF (0ºC): 4951 tape 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. To obtain good performance with all 3M™ VHB™ Tapes it is important to ensure that the surfaces are dry and free of condensed moisture.
Time
After application, the bond strength will increase as the adhesive flows onto the surface. 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. 150ºF (66ºC) for 1 hour). This can provide better adhesive wet out 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.
Adhesion Promoters
Adhesion promoters or primers are used to:
Increase adhesion to otherwise difficult to bond surfaces
Develop a faster, stronger bond
Seal non-unified surfaces such as wood or concrete
Increase bond durability and stability to substrates such as glass and copper
Provide a barrier from migrating materials such as those found in rubber or plasticized vinyl
Consult the 3M™ VHB™ Tapes Technical Bulletin "Surface Preparation for 3M™ VHB™ Tape Applications" for a suggestion of possible adhesion promoters or primers for each situation.
Note: It is important for the user to determine the suitability of the 3M™ VHB™ Tapes, primer and application process and compliance with local Air Quality Regulations.
Removal
The 3M™ VHB™ Tapes are intended for permanent applications. However, there are a variety of removal techniques that can be considered for breaking a bond and cleaning the adhesive residue from the substrate surfaces.
Because the 3M™ VHB™ Tapes stay soft and resilient the foam can be cut with a variety of tools, from a textured piano wire to a 3M SMART Tool. Because the 3M™ VHB™ Tapes are sticky all the way through use of a lubricant, such as soap, will make the job easier.
With small bonds the strength of the tape can be overpowered by prying or twisting. Removing at slower rates or at higher temperatures is generally easier.
The residue can be removed by abrasion such as with a 3M™ Stripe Off Wheel, can be softened with a variety of solvents, or can be baked off with high temperature. |
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