Silicone vs Acrylic Adhesive- A Comparison

8 June 2011- Silicon and acrylic adhesives are those rubber adhesives that are widely used in Polyimide tapes. In fact, the polyimide tapes have two layers- the polyimide film and the adhesive that is applied to that film. Although silicon adhesives are mostly used for the sealant layer, many applications require the tape to have acrylic adhesive. Why is this so can be only understood by comparing both the types of adhesives- the silicon and the acrylic adhesives.

Silicon Adhesives- The Characteristics

Silicone offers better elongation at break. It is applied for electrical insulation of electrical equipment. As it offers the highest heat resistance among film adhesive tapes, it is also widely used for high temperature insulation. Some of the characteristics of silicon adhesives are listed below for better understanding.

• Silicone is highly flexibile at sub-ambient temperature.
• It can give consistent performance over wide ranges of temperature.
• It has very good aging and UV resistance.
• It can withstand high temperature.
• Silicone also shows a good resistance to polar solvent.

Acrylic Adhesives- The Characteristics

Acrylic Adhesive TapesThere are two types of acrylic adhesives water-based and solvent-based. Water-based acrylic adhesives dry slowly as compared to solvent based adhesives. However, usually solvent-based acrylic adhesives show better resistance to other solvents, chemicals and water. Some of the characteristics of acrylic adhesives are as follows.

• Acrylic adhesives have a reasonable adhesion to a wide range of substrates.
• It has a good aging, transmittance and UV resistance that are suitable for fiber optic applications.
• It also shows a reasonable temperature resistance but not as good as silicone adhesives.
• It has a lower tack meaning it sticks less when dry.

Acrylic vs Silicone Adhesives

Now when we know the characteristics of both - silicone and acrylic adhesives, we can move on to compare both the types of adhesives.

Silicone adhesives can withstand higher temperature range as compared to acrylic adhesives. Acrylics have the property of being more brittle and as such they can crack at extremely low temperatures too. If we take the general view, acrylic adhesive have better adhesion at mid-range temperatures which means a temperature range that falls within 0°C to 100°C. On the other hand, silicone adhesives have higher adhesion at lower temperatures that is under 0°C as well as at higher temperatures that is above 100°C.

As such, it seems that silicone adhesives are more standard and preferred for most of the applications. However, some situations where silicone can not be used, one has to depend on acrylic adhesives. As far as the point of lower tack in pure acrylics is concerned, it has an alternative too for better performance. Modified acrylic or rubber adhesives can be used for a better tack. Pure acrylic adhesives are commonly used on tapes which are used for bonding, sealing or surface protection.

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