Common Chemistry of PSA Tapes

According to the Pressure Sensitive Tape Council, three characteristics define a Pressure Sensitive Adhesive (PSA): 

  1. Permanent tack
  2. Adhesion with light pressure
  3. No liquid-to-solid phase change

Unlike liquid adhesives, the chemistry in a tape is provided fully cured so there is no additional curing that takes place to form a bond. The bond is created by using mechanical interlocking and electrostatic interactions at the interface.

These characteristics give PSAs unique performance capabilities that can provide freedom when designing a product and increase production efficiency. Benefits may include:

Other benefits may include:

  • Instant handling strength after applying pressure
  • Easy application
  • Consistent bond thickness
  • Versatility, in various thickness options with and without carriers and functional foam cores
  • Precise application with preformed (converted) shapes
  • Preassembly possibilities throughout the value chain
  • Capability to bond with dissimilar materials without damaging surfaces
  • Ability to act as a metal-to-metal barrier for reduced galvanic corrosion

Pressure sensitive adhesives come in many formats and chemistries for various industrial bonding applications. Although specialty PSAs are available for specific applications, we will focus on providing a high-level overview of the three most common chemistries.

Acrylic Adhesive Tape

  • image of vhb tape used for signage applications

    Development of acrylics for pressure sensitive adhesives began because of the tendency of natural rubber to yellow and degrade when exposed to UV. Acrylic chemistry also tends to have higher internal strength than rubber chemistry.

    Acrylic tapes are the workhorse of industrial bonding. The ever-evolving capabilities of acrylic chemistry allow formulations to provide high or low temperature performance, adhesion to High, Medium, and Low Surface Energy (HSE, MSE, LSE) materials, or even unique properties such as flame retardancy. Acrylic tapes are provided in various thicknesses with and without carriers and functional foam cores. Functional foam cores of acrylic foam tapes offer specific performance benefits including strength and dynamic stress absorption. Acrylic tapes are found in nearly every industry.

  • Primary Advantages

    • Ability to bond to the widest range of materials
    • Widest variety of mechanical performance capability
    • Good resistance to aging and environmental conditions
    • Functional acrylic foam cores available for dynamic stress and vibration absorption

    Primary Disadvantages

    • Not as high temperature resistance as silicone, although very high temperature acrylics are available
    • Longer time to full strength than rubber, although handling strength is typically immediate after pressure and final strength is typically higher

Unlike “acrylics” used for liquid adhesives, the acrylic chemistry in a tape is provided fully cured so there is no additional curing that takes place to form a bond. The bond is created by using mechanical interlocking and electrostatic interactions at the interface.

Silicone Adhesive Tape

  • image of silicone adhesive tape

    Silicone-containing polymers can be used to create tape release liners due to their incredibly low surface energy but are also used to formulate the very adhesive itself.

    Silicone tapes are best known for their ability to bond to silicone and to tolerate a very wide range of temperatures – from -40 °F (-40 °C) to over 500 °F (260 °C).

  • Primary Advantages

    • Ability to bond to silicone materials
    • High temperature resistance
    • Relatively resistant to mold and fungi

    Primary Disadvantages

    • Relatively low strength
    • Low bond strength on non-silicone materials, although double coated tapes are available with silicone on one side and acrylic on the other to allow bonding silicone to non-silicone

Because silicone is “inorganic”, meaning that the backbone of the chemistry is non-carbon, it is inherently hypoallergenic and relatively resistant to molds and fungi.

Rubber Adhesive Tape

  • image of 3m filament tape for bundling metal rods

    Rubber was the first material used to make pressure sensitive adhesives. Over the decades, rubber PSA technology has advanced to include both natural and synthetic rubber resins and a wide variety of tackifiers used to tune the adhesive for specific performance.

    Rubber adhesives build the bond faster than other chemistries; they can bond to most surfaces including LSE and are relatively low cost. They are a versatile option for many applications, however their final bond strength is lower than acrylic PSAs and they are more vulnerable to the effects of aging (sunlight and oxidation).

  • Primary Advantages

    • Fast initial bond (high tack)
    • Adhesion to low surface energy substrates
    • Relatively low-cost solutions

    Primary Disadvantages

    • Lower ultimate strength compared to acrylic PSAs
    • Lower resistance to environmental conditions (e.g. UV, temperature)

Natural rubber (poly cis-isoprene) is mechanically worked to provide lower molecular weight polymers that can be readily dissolved or dispersed in a solvent. Synthetic polymers (such as styrene-isoprene block copolymers) may also be used. Tackifiers such as pinene (from pine sap, among other sources) are added to give the adhesive additional tackiness allowing it to be used as a PSA.

As with other adhesives, the chemistries and construction for tapes grow every day. New adhesives, new carriers and new manufacturing processes mean that new industrial tapes will continue to be developed.

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