How Hot Melt Adhesives Are Made?

Hot-melt adhesives (also known as hot glues) are generally 100% solid formulations based on thermoplastic polymers (no water or solvents are involved). Hot melts are solidify at ambient temperature and are ‘activated’ in the melt stage beyond their softening point, which is usually between 80 and 120 degrees. 

Hot melt is the name given to any polymer-based glue that is applied in a molten state. The application of the adhesive is usually by which works through either trigger action (i.e. EVA hot melt adhesives upon heating, PUR hot melt adhesives are moisture-cured) or finger pressure (Pressure-sensitive hot melts at ambient temperature).

How do hot-melts work?

Once melted (in a hot melt tank), the adhesive can then be applied onto a substrate in its liquified or molten state. The hot melt wets the substrate, penetrating the surface (and any cavities), and then it solidifies, ensuring cohesion. This setting/ cooling process takes very little time. Glues that cool and remain tacky are known as pressure sensitive adhesives (PSA) – these we will cover in depth another time.

How Hot Melt Adhesives Are Made?

Hot melt adhesives are thermoplastic materials that are typically composed of various polymers, resins, and additives. The manufacturing process involves several key steps:

1. Raw Material Selection

• Polymers: Commonly used polymers include ethylene-vinyl acetate (EVA), polyolefin (PO), and polyurethane (PUR).

• Resins: These enhance the adhesive properties and can include tackifiers and waxes.

• Additives: Fillers, stabilizers, and colorants can be added to modify performance characteristics.

2. Mixing & Heating

The selected raw materials are precisely measured and mixed together. The mixed materials are then heated to a specific temperature (i.e. 150 degrees) to achieve a molten state. This process allows the components to fully blend and achieve the desired viscosity.

3. Extrusion & Cooling

The molten adhesive is then extruded through a die, depending on the desired form (e.g., pellets, sheets, or blocks). Once shaped, the hot melt adhesive is cooled rapidly to solidify.

Flowchart illustrating our production process

In summary, how hot melt adhesives are made involves careful selection of materials, precise mixing and heating, shaping, cooling, and rigorous quality control to produce a reliable adhesive product.

At Free Bird Adhesives, we take pride in our decades of expertise in producing hot melt adhesives, providing solutions to customers across various industries worldwide.

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Published by TIANJIN SHENG-WANG ELECTRONIC CHEMICAL PLANT