Experts in Silicone Gasket Solutions
Experts in Silicone Gasket Solutions

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Silicone Rubber and Pressure Sensitive Adhesives – Silicone Adhesive, Acrylic Adhesive or Combination Adhesive (3M 9731) – Which is Best?

Updated on 9/25/2020

3M Adhesive Silicone SpongeWith so many pressure sensitive adhesive (PSA) offerings on the market today, it can be tough to figure out which adhesive is best for a particular application. Since it is not feasible to stock every adhesive, Stockwell Elastomerics has hand picked 20+ adhesive offerings with a well represented cross section of products available from major tape manufacturers. Most pressure sensitive adhesives offered by Stockwell Elastomerics can be applied to any silicone sponge, solid silicone and silicone foam as well as other gasketing products such as fluorosilicone, Poron urethane foam, neoprene, etc.

Silicone adhesives are most often specified when working with silicone rubber products or high temperature applications. Contrary to some ingrained industry thinking, acrylic adhesive can be applied to silicone products. Stockwell Elastomerics has several proprietary systems for preparing silicone sheet materials so they will readily accept acrylic adhesives. These systems have been used by Stockwell Elastomerics for over 30 years.

Acrylic Adhesive on Silicone Rubber

Stockwell Elastomerics has proprietary technologies that enable acrylic pressure sensitive adhesive to be applied to silicone. Acrylic adhesives are available in a wide range of thicknesses and adhesion properties (greater than 200 oz/in on stainless steel). Also, a new family of acrylic adhesives (the 3M 300LSE product line) has been designed to address adhesion challenges such as bonding to powder coats and low surface energy plastics. Acrylic adhesives have a reduced operating temperature range than silicone PSAs, with typical operating temperatures of -40°C (-40°F) to 149°C (300°F). There are some grades that can withstand short term exposure of 204°C (400°F). Acrylic adhesives tend to provide better performance than silicone adhesives (for temperatures under 400°F) and a longer shelf life, with the added benefit of being significantly lower cost.

• Wide range of options (thickness, strength, etc.)
• Lower cost
• High ultimate bond strength
• Longer shelf life

• Material preparation required (silicone rubber)
• Not recommended for less than -40°F or more than +300°F continuous

Example Products: 
3M 9485
Adchem 256M
3M 467

When working with silicone rubber and pressure sensitive adhesives it is important to understand the adhesive requirements. If the application requires very low or high temperature performance, silicone adhesive should be specified. If the temperature range of a silicone PSA is not required, significant cost savings as well as bonding performance can be gained by specifying an acrylic PSA.

Silicone Adhesive on Silicone Rubber

An advantage of silicone pressure sensitive adhesive is they can be bonded directly onto smooth silicone rubber foam and solid without any surface preparation. Also, silicone PSAs have a broad operating temperature -73°C to 260°F (-100°F to +500°F). The typical bond strength (to stainless steel) is 30 to 60 oz/in, which is relatively low when compared to acrylics that have typical values of 70 – 150+ oz/in. The cost for silicone PSAs can be 3 to 5 times the cost of acrylics.

• Broad operating temperature range
• No material preparation (on smooth silicone rubber)

• Moderate to low ultimate strength
• Higher cost
• The shelf life is limited – some manufacturers have 90 to 180 days

Example Products:
• 3M 9122 (transfer)
DP-1001 (double coated)

Combination Adhesive on Silicone Rubber

Combination adhesives are always double coated (or film supported). This means there is a support layer, typically PET, that is adhesive coated on both sides. The support layer is nearly invisible but unlike transfer adhesives they have X Y dimensional stability. With the combination adhesives the support layer is coated on one side with silicone and the opposite side with acrylic. These adhesives were designed for laminating to silicone rubber. The silicone PSA side bonds to silicone rubber, the end user exposes the acrylic side when the release liner is removed. The combination adhesives do not have the same operating temperature as silicone PSAs due to the PET layer and acrylic adhesive side which reduce the overall temperature range.

• No material preparation (smooth silicone rubber)

• Moderate to low ultimate bond strength
• Higher cost

Example Products:
3M 9731 (double coated)
• NT1060 (double coated)

For more information on silicone, combination, and acrylic adhesives use on silicone rubber material, and to request sample swatches, please call Stockwell Elastomerics at 215-335-3005 or complete a contact form for assistance.

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