What are EVA hot melt adhesives and how do they work?

In addition, most EVA hot melt adhesives do not undergo any chemical reactions, such as cross-linking or carrier removal, such as solvent evaporation. This means that; 100％  The formula is viscous and does not require obtaining the correct component ratios in the formula or during application. In addition, no additional processes such as mixing are required before or during use.

All EVA hot melt adhesives work by “wetting” the surface of the substrate that is bonded together, which is easy to achieve when the hot melt adhesive is applied in its liquid form. However, depending on the substrate temperature, hot melt adhesive may cool rapidly, which can sometimes make bonding with the second substrate difficult.

Hot melt adhesives have two main subcategories: pressure-sensitive adhesives (PSA) and non pressure-sensitive adhesives (non PSA). The difference lies in; PSA  Hot melt adhesive maintains its stickiness even after cooling to room temperature, while it does not adhere properly; PSA  When using hot melt adhesive, it is necessary to complete the connection of the substrate when the hot melt adhesive is very hot, in order to allow the adhesive to wet the two substrates and ensure good adhesion is completed.

Use  PSA  When heated, the substrate can bond, but depending on the adhesive and substrate used, this may occur at room temperature because the adhesive still has stickiness.

Characteristics of EVA Hot Melt Adhesive

The following characteristics need to be considered:; Applicable

Period stability

This is the time for the adhesive to stabilize at high temperatures. When using hot melt adhesive, it is important to ensure that the adhesive does not quickly decompose or break down at high temperatures.

Opening hours

This is the appropriate bonding time after applying the adhesive. This depends on the application temperature, as typically the higher the application temperature, the longer the opening time.

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This is related to the surface viscosity, which can be referred to as thermal viscosity, or; PSA  Hot melt adhesive – room temperature viscosity. Room temperature viscosity is usually measured using a rolling ball test; –  Although there are various other tests, including cyclic viscosity testing.

Softening point

This is the temperature at which EVA hot melt softens; However, it will lose its cohesive strength at lower temperatures, especially under strain. Usually, rings and balls are used to measure the softening point.

Melt viscosity

This is the viscosity of hot melt adhesive at high temperatures. It is necessary to specify the temperature for measuring viscosity, as this will decrease with increasing temperature. This can be measured using a rotary spindle viscometer and a heating chamber or cone plate rheometer.

Hot melt adhesive is a widely used, low-cost, and easy to apply adhesive that can be used in various industries. Compared to many other adhesives, they are safer in the environment and pose less harm to operators, making them a great alternative. However, in order to fully utilize hot melt adhesive in each use, it is necessary to use the correct application parameters and adhesive.