Acrylic Resin vs. Epoxy Resin
Acrylic resin is a type of thermoplastic that can be repeatedly heated and shaped. It combines acrylic polymers with dry powders, a thin liquid, methyl methacrylate monomers, and a hardener. It’s different from epoxy resin because it can be reshaped with heat for further manipulation. Acrylic resin is strong, durable, and resistant to UV damage. This makes it ideal for a variety of applications, including outdoor use.
Epoxy resin is a thermosetting material used to create hard, durable castings, coatings, and adhesive products. It comes in a liquid form that cures quickly and adheres to different substrate materials like glass, wood, stone, concrete, and metal. The liquid epoxy is combined with a chemical hardener which cures it into hardened plastic. Once the mixture is set, it cannot be remolded or reshaped. Epoxy resins are very strong and resistant to chemicals, electrical damage, and heat. This makes them ideal for use in high-stress environments and applications requiring strength and durability.
The formulas
An epoxy is formed by blending epoxy resin with some type of amine. After this combination cures for a moderate amount of time (>6 hours at 75° F), it forms long cross-linked polymer chains, known for strength, durability, and water resistance.
Epoxies are sensitive to the mix ratio (typically, 1:1 or 3:1) between the resin and hardener, so must be blended well to achieve full performance. It’s worth noting that low temperatures increase viscosity and reduce molecular mobility, which hampers the cross-linking (curing) of most epoxies.
Vinyl ester — a type of hybrid adhesive — is formed by free- radical polymerization, made by the esterification of an epoxy resin with acrylic or methacrylic acids. This process happens rapidly (<1 hour at 75° F) due to curing via a chain reaction that can occur at both low and elevated temperatures. Vinyl esters and hybrid urethane- methacrylates are less sensitive to the mix ratio (typically, 10:1) between the resin and catalyst. But they’re usually affected by the presence of moisture during cure, and much more so than their epoxy counterparts.
In many cases, an epoxy or a hybrid will meet your specification requirement, so it’s important to know the key differentiating factors between these two primary classes of adhesives.
Temperature and bond strength
The temperature at an installation site is often an important and relevant factor when deciding what type of adhesive to select.
Epoxies become harder to dispense at lower temperatures and cure very slowly as temperatures approach the 40° F mark. At extremely high temperatures, epoxies are easy enough to dispense, but they begin to lose some of their performance properties, which may be far from ideal for certain applications.
When temperatures are either very high or low, a vinyl ester, acrylic, or hybrid can offer an alternative.
Applications that carry critical safety considerations tend to specify products based on their bond strength, and not every solution will meet these stringent requirements. Typically, epoxies outperform their acrylic and vinyl ester counterparts in this arena.
Some hybrid adhesives also carry high bond strength numbers but are unlikely to compete with epoxies at the highest end of the bond strength chart. Therefore, when bond strength requirements are paramount, an epoxy is typically going to win the specification. This said, acrylic adhesives and hybrid formulations carry other beneficial characteristics that could make them ideal for your project, particularly when factors other than bond strength are important.
Applications
Acrylic resin is a versatile material that is used in a variety of applications, including:
Brake lights: Acrylic resin is durable and resistant to fading, making it an ideal material for brake lights.
Phone screens: The material is also applied to phone screens because it’s lightweight and shatter-resistant.
Dentures: Acrylic also can mimic the appearance of natural teeth and is often used for dentures.
The strength and durability of epoxy make it ideal for industrial and commercial use, while its aesthetic properties make it popular for arts and crafts projects. Some of the most common uses for epoxy resin include:
Adhesives: Epoxy is well-suited for adhesives because it forms a strong bond and is resistant to high temperatures and chemicals. It is commonly used to adhere metal, glass, and plastic components together.
Industrial tools: Tools made with epoxy resin are incredibly durable and can withstand heavy use.
Electrical components: Epoxy resin is an insulator, making it ideal for electrical applications.
Repair and maintenance: Frequently used in repair and maintenance applications because it can effectively fill in cracks and gaps.
Artwork: Epoxy resin can be used to create beautiful artwork. It can be cast into shapes or molded into three-dimensional designs. It can also be used as a protective coating for paintings or photographs.
