Pressure Sensitive Tape: What to Know
What is a Pressure Sensitive Adhesive (PSA)?
Pressure sensitive adhesive (PSA, self adhesive, self stick adhesive) is an adhesive tape that is permanently tacky and adhere spontaneously to a surface with only light pressure. Pressure Sensitive Adhesives do not require solvent, water, or heat to activate the adhesive. Rather, they are bonded by the initial force of application. PSA will adhere to a variety of diverse materials such as paper, glass, wood, plastic or metal, when applied to clean and dry surfaces with no more than finger or hand pressure. A PSA has a balance between adhesion and cohesion forces.
Advantages of Pressure Sensitive Adhesives:
- Thinner and lighter materials
- Bonds various substrates
- Inherently tacky
- Tailorable to the application
- Can serve a variety of temperature ranges
- Eliminates the need for surface refinishing
- Eliminatesthe need for mechanical fasteners
- Safe and easy to install or apply.
- Cost effective to apply
Three types of Pressure Sensitive Adhesives:
Rubber - Rubber adhesives are based on natural or synthetic rubbers. Rubber adhesives are the most cost effective with quick stick characteristics. Rubber adhesives are not recommended for high temperature applications.
Acrylic - Acrylic adhesives are formulated with acrylic polymers. They generally possess resistance to environmental factors giving them better long-term aging. Acrylic adhesives tend to develop a stronger bond than rubber adhesives and can withstand higher temperatures.
Silicone: Silicone adhesives are formulated with silicone polymers and thus are the only adhesive that will bond well with silicone substrates. These adhesives are generally higher priced and possess a very low initial tack.
Four ways pressure sensitive tapescan be constructed:
Single Coated: A pressure sensitive tape consisting of a carrier with adhesive coated only on one side. Common examples of single coated tapes include electrical tapes, masking tapes, carton sealing tapes, and medical tapes.
Transfer Tape: An unsupported pressure sensitive tape. Transfer tapes generally consist of an adhesive and a coated release liner. Common examples of transfer tapes includeenvelope sealing, graphic attachment, and splicing tapes.
Double Coated Tape: A pressuresensitive tape consisting of a carrier with adhesive coated on both sides. Typically, a liner is necessary to unwind the roll. Common examples of double coated tapes include mounting, medical and membrane switch tapes.
Self-Wound Roll - A roll of pressure sensitive tape in which each layer of tape is directly on top of the last one. The roll contains no liner. Common examples of self-wound tapes include carton sealing, duct tapes and masking tapes.
Proper Application of A Pressure Sensitive Adhesive Tape
As the name indicates, pressure sensitive tapes need pressure to ensure bonding.
Surface Preparation -The surface to which the tape is applied should be clean, dry,and free of oils or grease. To properly clean the surface, a lintless cloth should be used. Suitable solvents for use include benzenes, alcohols, esters, and ketones. Ensure that the substrate is able to withstand the solvent prior to application.
- Recommended bonding pressure is 14.5 29 psi =^ 10 20 N/cm.
- The pressure is needed to ensure that the tape comes in close contact to the surface so that the physical forces between the adhesive and the surface can build up.
- The tape should be applied at moderate temperatures between 59 F and 95 F.
Surface Energy/Tension -To ensure the best possible adhesion, it is optimal that the surface onto which the tape is applied has a higher surface energy or polarity than the tapes adhesive system.
NOTE: There are some substrates that are generally easier to bond to than others. These are the materials with higher surface tension/energy. It is important to know that coatings on the surfaces or fillers in the substrates might influence the adhesion characteristics. A painted aluminum or plasticized PVC (polyvinyl chloride) might display completely different bonding characteristics as compared to pure, unaltered materials.
To increase the surface tension of substrates with low-surface energy, consider using a primer or adhesion promoter. Corona or flame treatments can also be applied. It is critical that adhesive systems and primers are cooperative in nature. Testing is, of course, always critical to ensure the desired result.
Pressure sensitive tapes need to be stored under defined conditions.Extreme high temperatures can lead to degradation of the adhesive or backing materials. Extreme low temperatures might influence the bonding characteristics.
The recommended storage conditions are:
- 68 - 72 F / 20 - 22 C
- 50% relative humidity
- Rolls store flat in their original packaging, away from direct sources of UV (i.e., lights, sun).
Questions to Ask About The Application