What is Ethylhexyl Acrylate used for in polymers? 2-Ethylhexyl Acrylate (2-EHA ) is a highly versatile building block that readily copolymerizes with a wide variety of other acrylic and vinyl monomers to tailor specific high molecular weight copolymer properties for a diverse range of non-rigid applications. 

For over 45 years, Gantrade has served customers worldwide, including those who specialize in the production of paint and coatings, adhesives and sealants, printing inks, and super-absorbent polymers. These companies know us as a leader in delivering high-quality products like 2-EHA consistently, with technical advice they can count on to make the right decisions that optimize their products.

As a higher alkyl acrylate comonomer, 2 Exylhexyl Acrylate uses a range of factors to impart a glass transition temperature that is well below room temperature (homopolymer Tg is – 65°C), flexibility, elasticity, and hydrophobic qualities. Unique features the compound contributes to copolymer compositions include low-temperature flexibility, water resistance, good weathering characteristics, and UV (sunlight) resistance. 

Primary applications that take advantage of these characteristics include multiple adhesives, especially pressure-sensitive adhesives (PSA), paint & coatings, caulks & sealants, textile & paper finishes, and printing inks.

Applications of 2-Ethylhexyl Acrylate (2-EHA)

Because 2-EHA contributes to clarity, toughness, and light, weather, and chemical resistance, manufacturers can use acrylic copolymers containing 2-EHA in interior, exterior, basecoat, and topcoat paint & coating formulations, as well as other related products.

New areas of technical advancements for 2-Ethylhexyl Acrylate uses exist in the homopolymer, poly(2-ethylhexyl acrylate), as a plasticizer material for surface coatings, film, sheeting, and pressure-sensitive adhesives and tapes. As a plasticizer incorporated into PSAs, it results in an increase in peel strength and tack. 

At the same time, it improves removability, making it great in areas that may need to be regularly recoated. 2-EHA is used in superabsorbent copolymers to produce fast-swelling, highly-porous hydrogels for diapers and hygiene products.

Growth in paints & coatings, adhesives & sealants, printing inks, and superabsorbent polymers are driving the global 2 Ethylhexyl Acrylate uses market.

Attributes of 2-EHA as a comonomer include:

• A low Tg -65°C and low-temperature flexibility
• Facilitates design of softness and tackiness in copolymers
• Excellent copolymerization characteristics
• Entanglement of the C8 side chain facilitates macromolecular entanglement (Me)
• Improves water resistance and weathering
• Suitable for external applications.
• A low order of toxicity
• Availability and commodity economics

The performance profile of 2-Ethyhexyl Acrylate uses has led to a strong growth rate in commercial applications, including 2-EHA homopolymers and copolymers that comply with numerous sections of the Code of the Federal Register (21CFR) for adhesives, coatings, and indirect food additives.

The Versatility of 2-EHA

In a world where supply chain shortages have become commonplace, we have maintained strong supplies of 2-EHA to meet a wide variety of needs for customers representing multiple manufacturing sectors. 

2-Ethylhexyl Acrylate uses include being a key monomer in a wide range of copolymer compositions. Free-radical polymerization techniques afford high monomer conversions and very high macromolecule molecular weights (>200,000). The ease of handling and co-polymerization of 2-EHA allow for use in emulsion, solvent, suspension, and bulk polymerization uses.

The molecular formula of 2-EHA, as shown below, illustrates the long-chain branched structure of this unique monomer.

As we describe below, the long C8 chain structure contributes to side-chain entanglement, leading to an increase in cohesive strength as 2-EHA content is increased

Acrylate esters in general, which include 2-EHA, BA, MMA and GAA, represent a versatile family of building blocks for thousands of copolymer compositions. Copolymerization can lead to well-designed properties required in a broad range of end-use applications. 

Styrene monomers and short-chain acrylic monomers such as methyl methacrylate produce harder, more brittle polymers, with high cohesion and strength characteristics. Long-chain monomers such as 2-EHA and BA enable soft, flexible, tacky polymers with lower strength characteristics, increasing adhesion, elasticity, and flexibility.

By managing the comonomer ratios and the glass transition temperatures, the chemist can balance hardness and softness, tackiness and block resistance, adhesive and cohesive properties, low-temperature flexibility, strength, durability, and other key properties to facilitate end-use goals. 

Functional monomers such as diacetone acrylamide, (meth)acrylic acid, glycidyl acrylates, and maleic anhydride can be incorporated as crosslinking agents and/or as cure accelerators. 

Monomers including acrylonitrile and (meth)acrylamide can improve solvent and oil resistance. To learn more about these use cases, see our article on the technology of DAAM and ADH crosslinking in acrylic polymers.

Pressure Sensitive Adhesives (PSAs) based on 2-EHA

Chemists facilitate the rational design of PSAs by the availability of monomers such as 2 Ethylhexyl Acrylate that uses unique properties in adhesive copolymer compositions. 

The challenge in designing PSAs is to balance properties like adhesion and cohesion, tack, shear, and peel strength, high and low temperature performance, hardness and softness, and removability and permanence. 

An understanding of the copolymer contributions of 2-EHA and other complimentary monomers can assist in the engineering of copolymer compositions to meet performance profiles required for various end-uses.

In one study, the effect of 2-EHA monomer content on the peel strength and shear strength of an acrylic emulsion PSA prepared from 2-EHA, BA, 2-HEA, and GAA was determined. Peel and shear strength increased with increasing 2-Ethylhexyl Acrylate uses and quantities. 

However, the loop tack decreased as the 2 Ethylhexyl Acrylate uses and quantities increased. The 2-EHA content had a strong effect on the flow of the adhesive and substrate-wetting characteristics. The shear strength increase was ascribed to chain entanglement of the 2-ethylhexyl side chain, an interesting feature of the long-chain in the 2-EHA acrylate monomer.

In another study, investigators looked at the effect of varying the n‐butyl acrylate/2-EthylhexylAcrylate uses ratio in the monomer feed on copolymer PSA characteristics. These compositions also contained a low constant level of acrylic acid. The results showed that increasing the amount of 2-EHA reduced the glass‐transition temperature and decreased the gel content of the copolymer, up to 50% 2-EHA; thereafter, gel content increased. 

They observed a synergistic effect leading to increased shear resistance at 25 wt.% 2-EHA without a significant trade‐off in the peel and tack properties. The investigators attributed this behavior to the cooperative entanglement of the 2-EHA units in the free copolymer chains and with the microgel particles.

Cooperation between various levels of 2-EthylHexyl Acrylate uses in the copolymer structure simultaneously changes the crosslink molecular weight (Mc) of the microgels and the entanglement molecular weight (Me) of the free chains in the network morphology. 

The adhesive performance of the PSAs correlated with their Mc/Me values as the 2-EHA proportion was varied. Other observations included an increase in tack strength and a decrease in peel strength with increased 2-EHA levels. Increasing 2-EHA in the feed reduced the polymerizations rates vs. butyl acrylate.

Paint and Coating Applications of 2-EHA

Gantrade serves a large number of customers in the paint and coatings industry worldwide, and these clients know that a strong, dependable supply of 2-EHA is important to meet a variety of product applications. When used in paint and coating formulations, 2-EHA copolymers exhibit good water resistance, low-temperature flexibility, durability, and good weathering and sunlight resistance.

Acrylic-based coatings can be classified into all-acrylic formulations in which the building blocks are exclusively acrylic and methacrylic ester types; styrene-acrylic formulations which also contain styrene; and vinyl-acrylic formulations which also contain vinyl acetate monomer (VAM).

The various monomers used in the copolymers can differ widely in glass transition temperature (Tg); copolymer hydrophobic-hydrophilic balance; hardness and flexibility; and weathering and sunlight resistance. Even with a fixed Tg, copolymers with different monomer combinations vary significantly in the properties of the final paint and coatings. The most common paint formulations are copolymers of BA and 2-EHA with MMA or BA and 2-EHA with VAM.

Acrylic copolymer formulations often contain four or more different monomers. The glass transition temperature of a random copolymer can be estimated by using the weight fraction of the different monomers and their Tg values for the homopolymer. This method assumes that the repeat unit of the copolymer can be divided into weighted additive contributions to the Tg that are independent of their neighbors. Reference Tg values for several key monomers are shown below:

For a discussion on estimating the Tg of random copolymers please see this article: https://www.highbeam.com/doc/1G1-17351275.html. Please contact us for additional details.

In the important area of weatherability and sunlight resistance, BA copolymers exhibit the greatest photostability, while styrene and VAM lower the photostability. 2-Ethylhexyl Acrylate uses are slightly more photosensitive than BA but are also much superior to styrene and VAM. 2-EHA copolymers are hydrophobic and show the least amount of dirt pick-up in exterior coatings or staining with hydrophilic substances.

Other Application Areas

We can apply the formulating principles delineated above to the other major application areas for copolymers in 2 Ethylhexyl Acrylate uses in the co-monomer compositions. Additional end-uses for 2-EHA copolymers include printing inks, non-woven fabrics, textile and paper coatings, leather finishing, caulks and sealants, and additives in products such as lubricant oils and fuels.

Gantrade’s Sales Specifications for 2-EHA are shown below:

2-EHA is available from Gantrade Corporation in rail tank cars and road tank trucks. When storing 2-EHA, it should be kept at temperatures below ~ 25 °C (<80 °F). When used with MEHQ inhibitor, the product must be stored in an air atmosphere since the presence of oxygen is required with this stabilizer.

Conclusion

As you can see, 2-EHA is one of the major base monomers used in the manufacture of copolymers for adhesives & sealants, paint & coatings, printing inks, superabsorbent polymers, and a myriad of other application areas. Among the 2 Ethylhexyl Acrylate uses is its action as a unique building block for copolymers, contributing low-temperature flexibility, performance, hydrophobicity, water resistance, good weathering characteristics, and UV (sunlight) resistance.

If you're looking not just for a supplier, but for a partner you can trust for cost-effective supply and timely advice, contact Gantrade Corporation today. Our team has developed deep expertise over our more than four decades in the industry, providing high-quality industrial chemicals and chemical products to manufacturers, contractors, and other interested parties. That high level of expertise helps you make smarter decisions for your business. We look forward to speaking with you.

Safety Update

A recent study with 2-Ethylhexanoic acid (2-EHA) did not indicate any adverse effects regarding reproduction at the highest dose tested. As a result, ECHA has finalized the Community Rolling Action Plan (CoRAP) evaluation, and 2-EHA is no longer under consideration for additional classification. The product is considered safe with risk mitigation measures in place.