Hot melt adhesives are the most popular, and widely used types of industrial adhesives currently available in today’s market. Hot melt adhesives are polymer based, and are thermoplastic in nature, meaning they are solid at room temperature. These adhesives do not utilize water, or solvents in order to acquire their adhesive properties, which allows them a very fast set time, a long shelf life, and functionality in a wide range of temperatures.

Hot melt adhesives service a wide range of industries for various applications, including the paper and packaging, woodworking, graphic arts, assembly, and automotive industries. Today we’ll be taking a look at the EVA family of hot melt adhesives; how they are made, and in what industries they are currently in use for.

Ethylene-Vinyl Acetate Hot Melt Adhesives

There are two main types of industrial hot melt adhesives: ethylene vinyl acetate (EVA) and polyolefin, or metallocene. EVA is a copolymer adhesive, most commonly used in the paper, packaging, and assembly industries, as they bond to a variety of cellulosic materials and have a wide range of formulation. The composition of the adhesive will directly influence its properties. Because they can be specifically formulated for various applications, there are several kinds available on the market.

Formulation and Composition

Ethylene promotes adhesion to non-polar substrates such as polyethylene, and provides mechanical strength, block resistance, and paraffin solubility. Vinyl acetate, on the other hand, promotes adhesion to polar substrates such as paper, and provides flexibility, adhesion, and better low-temperature performance. How the adhesive is formulated will directly influence its properties.

For example, a higher ratio of ethylene in the formulation will provide the specific EVA adhesive with increased strength and resistance, while a greater amount of vinyl acetate will provide stronger adhesion to paper products and improve the flexibility of the adhesive. Formulations that contain higher amounts of vinyl acetate can also operate in lower temperatures, have improved wettability (industry term) to substrates, and has a longer open time and slower set time.

Properties of EVA

Although EVA adhesives vary in properties depending on their specific formulations, in general, they bond to the broadest range of substrates, function in one of the widest temperature range for hot melt adhesives, and, on top of everything else, are the most affordable. EVA hot melt adhesives generally require an application, or melting temperature of 350 degrees F, and have a wide viscosity range of between 900-3,000 cPs.

For the most part, EVA adhesives have a relatively fast set speed. However, it is important to remember that if you are using a formulation with a higher ratio of vinyl-acetate, the set time will be somewhat longer. EVA adhesives can function in temperatures as low as -40 degrees F and as high as 160 degrees F, again depending on the formulation.

Industries and Applications

Because of their versatility, dependability, and durability, EVA hot melt adhesives are used in a wide range of industries, for a variety of applications. These industries include the paper, woodworking, assembly, and automotive industries, to name a few. Perhaps the industry most frequently utilizing EVA hot melt adhesives, however, is the packaging industry.

EVA adhesives are specifically formulated to adhere to waxes, paper, paper stock, and various aqueous coatings. For this reason, they are ideal for use in the packaging industry, which deals with a variety of products and industrial applications.  These products include, but are not limited to paper/card stock boxes, package labeling, carton sealing, assembly, and paper conversion.

Bulk Hot Melt Adhesives

Remember, because EVA hot melt adhesives are specifically formulated for your particular industry or application, there is no one EVA adhesive that is formulated for a wide range of bonding applications. Factors that will affect the end formulation of the specific adhesive include what substrates need to be bonded, the required application techniques, including speed of application and set time, and also the environment in which the adhesive is being used.