Applications & Uses of Pressure-sensitive Adhesives

The versatility of pressure sensitive adhesives is so enormous that complete tabulation of all their uses is virtually impossible. Future applications appear to only be limited by the innovative spirit of the adhesive manufacturers, tape converters, and end-users.

There are a number of inherent advantages of PSAs for the end-user over other adhesives and fastening methods. These classical and well-known advantages have propelled the use of PSAs into almost every industry. Some of these inherent advantages include:

The ability to employ lighter, thinner materials
The ability to bond dissimilar materials with few concerns about incompatibility
Shortened assembly times and improvements in productivity (for the end-user no cure cycle or necessity to remove solvent)
Minimal issues of health, safety, and disposal
Elimination of visible mechanical fasteners
The ability to adhere to difficult surfaces such as human skin
Uniform thickness throughout the product
Elimination of the need to bond both substrates together at the same time and location

Product polarization will likely significantly impact the adhesive tape industry in the future. Polarization refers to a split between increasingly low priced products for commodity use and products with high degrees of value added and specialization. Specialty tapes, created for specific industries or applications, have and will continue to see strong growth of approximately two to three times the industry as a whole.

These higher valued products will be used in increasing sophisticated applications. The future specialty tape market will exhibit three primary mandates: demand for new functions, demand for enhancement of existing functions, and demand for multifunctionality. Of these, the demand for multiple functions appears to be most important.

Factors to Consider while Using PSA

Following are the application factors that need to be considered when using pressure sensitive adhesives:

Price target
How the product is applied
Expected usage (volume)
Condition of substrates
The function that the adhesive must provide
Exposure to UV light, solvents, and other degrading environments

Materials to be jointed
Texture of substrates
The temperature at application and during use
Migratory components of the substrate
Product life expectancy

Application factors for Pressure Sensitive Adhesives²

Interesting Application in Focus

New applications are driving the labels market more than they do for the tape market due to the many important functions that a label provides other than joining. These novel applications include:

Transparent labels with the "no-label" look
Adhesive tack at low temperature for frozen food application
Removable labels
Scratch-off and aromatic labels, and
Embossable-image tapes for lettering guns

The best example of this is the "smart label", which is capable of integrating bar coding, anti-shoplifting, and logistics features. These labels include tamper resistant elements involving inks, substrates, holograms, coatings, and even adhesives.

Another interesting application for pressure sensitive adhesives is delayed action adhesives (DAA). These adhesives are not pressure sensitive as they come from the label converter. Just prior to final label application the label is momentarily heated and the label becomes pressure sensitive and tacky to the touch. Tackiness is achieved because the DAA coating consists of a discrete mixture of at least two different solid plasticizers held to the label with a binder vehicle. When the label is heated, the plasticizer forms a eutectic melt, which has a melting point lower than their individual plasticizer melting points.

Get inspired: Get PSA formulation strategies for tapes & labels »

The pressure sensitive adhesives (tapes) can be made to be permeable or impermeable to a number of gases and moisture vapor. Permeable tapes also allow the assembly of medical devices and test strips for determining pregnancy or diabetes. Several applications are in the medical market with PSAs that incorporate active ingredients such a nicotine, vitamins, and medications. The adhesive tapes stick to the skin and allow the medications to diffuse at a known rate without interacting with the drug.

Permeable tapes allow the assembly of medical devices and test strips for determining diabetes

In electronic products a significant trend is to manufacture smaller, more powerful, and more portable products. Double sided foam backed tapes are increasingly being used as an alternative to fastening with conventionally chemically reactive soft glues. In particular the microelectronics industry uses a large number of PSA layers for the construction of components. Electronics designers need materials that are rugged, durable, and lightweight. Advances in tapes enable them to bond, seal, and absorb shock. They are easy to apply, lightweight, and can be die cut to fit the smallest and most unusual shapes. As a result, they are being used for flexible circuit bonding, EMI/RFI shielding, protective masking, electrical insulation, and general component assembly.

Double sided foam backed tapes for electric circuits

Temperature resistance has always been an issue when selecting pressure sensitive tapes for certain applications. Conventional PSAs are thermoplastic in nature and susceptible to creep at moderate temperatures. To solve these issues, tape manufacturers and end-users are increasingly going to UV cured, high performance PSAs.

Acrylics, modified polyurethanes, silicones, and SBS/SIS rubber can be UV crosslinked. Manufacturers can also achieve better heat and creep resistance by adding to the formulation materials that allow for crosslinking after application. Hot melt applied, moisture curing polyurethane hot melts are excellent examples of such innovation. These materials not only provide the heat resistance of a thermosetting adhesive, but they can also be applied at temperatures that are much lower than conventional hot melt temperatures.

Applications of Pressure-sensitive Adhesives

Factors to Consider while Using PSA

Interesting Application in Focus

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