User manual 3M VHB TAPE SURFACE PREPARATION TECH. BULLETIN

[. . . ] (Steps C and D) Generally, this means that the tape should experience at least 15 psi (100 kPa) in roll down or platen pressure. (Sources- page #4) · After application, the bond strength will increase as the adhesive flows onto the surface. At room temperature, approximately 50% of the ultimate strength will be achieved after 20 minutes, 90% after 24 hours and 100% after 72 hours. In some cases, bond strength can be increased and ultimate bond strength can be achieved more quickly by exposure of the bond to elevated temperatures (e. g. [. . . ] Avoid grinding a surface with coarse abrasive materials, since they may create too rough of a texture for the adhesive to adequately flow into the surface. Always clean the surface with the IPA/water solution or additional methods previously described, and be certain that all loose particles are removed prior to bonding. Exceptions to these abrading guidelines are 3MTM VHBTM Tapes 4932 and 4952, as they typically perform best on smooth glossy surfaces and abrasion may reduce the bond strength. Abrasion Adhesion Promoters Priming a surface can significantly improve initial and ultimate adhesion to many materials such as plastics and paints because of their low surface energy or the additives they may contain. A primer creates a new surface for VHB tape to adhere to and can also create a layer that may impede the migration of additives that may be present in a material. It is important for the user to determine the suitability of the VHB tape, the adhesion promoter and the application process. Rough, porous or fibered materials such as wood, particleboard, cement, etc. , have an open surface and require sealing to provide a unified surface for tape bonding. Common sealing materials would include paint, varnish or other hard surface coatings. Fast drying 3MTM Rubber and Vinyl Spray 80 can also be used to unify the surface and improve the tape bond. Glass, stone, ceramic or other siliceous materials are hydrophilic (water-loving) by nature. Normally, the hydrophilic nature makes pressure sensitive adhesive bond durability susceptible to change under high humidity or exposure to moisture. In basic terms, water vapor can undercut the tape bond and interfere with the normal adhesion forces. Silane coupling agents, added to the IPA/water cleaning solution, can help reduce the "water-loving" tendency of these surfaces and enhance the tape bond in high moisture environments. Copper, brass, and bronze are prone to oxidation even after the VHB tape is applied. To prevent a weakening of the bond, a lacquer or varnish should be applied to these surfaces. Be sure to test the tape bond to the sealer on a metal surface to verify good adhesion. Flexible PVC (vinyl) contains plasticizers that can migrate into the tape and affect adhesion. There are several VHB Tapes that are formulated to be resistant to plasticizer migration, or 3MTM Scotch-GripTM Plastic Adhesive 2262, thinned, can serve as a barrier to migration. EPDM, neoprene) can have low surface energy and may also contain plasticizers and oils. These require the use of an adhesion promoter for stable bond strength. Test for compatibility with flexible PVC and rubber materials by aging bonded samples for a week at 150°F (66°C) and check for softening of the adhesive, discoloration or reduction in bond strength. Porous Surfaces Unique Surfaces *Note: These cleaner solutions contain greater than 250 g/l of volatile organic compounds (VOC). [. . . ] · 3MTM Adhesion Promoter N-200J is available from PRC DeSoto at (317) 290-1600. · Silane Coupling Agent is available premixed in a 70:30 IPA/water solution or as a concentrate. % level of silane* adhesion promoter diluted in a 70:30 IPA/water cleaning solution has been found to be sufficient. Suggested Sources for Silane Coupling Agents: Custom-Pak Products, Inc. [. . . ]