With the continuous development of the global economy, industries such as packaging, hygiene and medical supplies, daily consumer goods, footwear materials, electronics, automotive manufacturing, woodworking, cosmetics, construction materials, furniture, handicrafts, and stone processing have experienced rapid growth.

    In line with this trend, hot melt adhesives have become an indispensable bonding solution across numerous industries. In China, the hot melt adhesive industry has been developing for over 30 years. Some hot melt adhesive technologies were first introduced domestically in the mid-1980s, initially serving applications such as bookbinding and sanitary napkin manufacturing. At that time, production scales were relatively small, and industry growth was slow.

    By 1993, national hot melt adhesive output was only around 10,000 tons. However, with the continuous advancement of economic reform and opening-up policies, along with improvements in manufacturing capabilities, production technology, and industrial scale, the hot melt adhesive industry has since entered a phase of rapid and sustained development.

    Despite this progress, many users still face challenges when selecting the appropriate hot melt adhesive for their specific applications. Understanding the key performance parameters that affect hot melt adhesive quality is essential for making the right choice.

    Below, Poseidon Material Technology’s technical experts—drawing on many years of industry experience—provide a detailed explanation of the critical parameters that influence hot melt adhesive performance. We hope this information will serve as a valuable reference and help you select the most suitable adhesive for your application.

Key Parameters of Hot Melt Adhesives

    Hot melt adhesive performance is determined by several critical parameters. These factors directly influence processing behavior, bonding quality, and end-use reliability.

1. Viscosity

    Viscosity determines the adhesive’s fluidity and flow behavior during application. It affects:

• Penetration into substrates
• Spraying and coating performance
• Application temperature requirements
• Stringing behavior
• Glue output and pumpability

    Proper viscosity ensures smooth processing and stable bonding.

2. Softening Point

    The softening point is the temperature at which the adhesive transitions into a fluid state. It directly influences both high- and low-temperature resistance of the bonded system.
    Different raw materials (EVA, PO, PA, PUR, etc.) result in different softening points, making this parameter crucial for selecting the right adhesive for specific operating environments.

3. Open Time

    Open time refers to the period during which the adhesive remains tacky after application. It affects:

• Processing speed
• Substrate wetting and penetration
• Final bonding strength

    An appropriate open time improves production efficiency and bond reliability.

4. Setting (Curing) Speed

    Curing speed determines how quickly the adhesive develops handling strength. It influences:

• Production line speed
• Operational suitability
• Bond strength development

    Fast setting supports high-speed automation, while slower setting allows better penetration and alignment.

5. Adhesion (Affinity)

    Adhesion reflects the adhesive’s ability to bond to specific substrates. Good affinity ensures strong and durable bonding between the adhesive and the material surface.

6. Cohesion

    Cohesion refers to the internal strength of the adhesive itself. It affects:

• Resistance to adhesive transfer
• Peel strength
• Shear strength

    High cohesion prevents adhesive failure under stress.

7. Thermal Adhesion

    Thermal adhesion describes the bonding performance during reheating or thermal cycling. It directly impacts bond stability in applications exposed to repeated temperature changes.

8. Temperature Resistance

    Temperature resistance defines the range within which the bonded system maintains performance.

      High-temperature resistance: Prevents softening or bond failure at elevated temperatures

      Low-temperature resistance: Prevents brittleness and debonding in cold environments

    For example, an adhesive rated for –10°C to 120°C will lose adhesion if operating conditions exceed this range.

9. Equipment Compatibility and Process Conditions

    Application equipment, operating temperature, coating method, and process parameters significantly affect adhesive performance. Proper matching of adhesive formulation with equipment and process technology is essential for optimal results.