Application of Polyethylene Wax in Hot Melt Adhesive Systems
Hot melt adhesives mainly consist of polymers and their compounds, which should have appropriate melt viscosity, melting temperature, curing time, hardness, and good adhesion to substrates to provide excellent peel, shear, and tensile strength. Depending on the application scenario, properties such as breathability, lightness, porosity, and wash resistance may also be required. Selecting the right adhesive based on different application scenarios helps meet desired requirements, enhance coating flexibility, and reduce costs.
Hot melt adhesives can be divided into two categories based on their base resins and formulations: thermoplastic polymer-based systems and reactive hot melt adhesive systems. Thermoplastic polymer systems soften or cure solely in response to temperature changes, including ethylene-vinyl acetate (EVA), polyamide (PA), polyethylene (PE), polyvinyl chloride (PVC), and polyester-based compounds. They are sensitive to steam and water, and their application range is limited due to low softening points.
Reactive hot melt adhesives undergo complete cross-linking through reaction with moisture after being applied to substrates. Once cross-linked, heating does not soften the adhesive. They are highly durable, offering excellent boiling resistance and weather resistance, but are relatively expensive.
|
Hot Melt Adhesive |
Characteristics |
Application Scenarios |
Price Range |
|
Low-Density Polyethylene（LDPE） |
Low cost, inertness. |
Used in fusible interlinings and automotive carpets |
Low |
|
High-Density Polyethylene（HDPE） |
Low cost, inertness, higher heat resistance than LDPE |
Used in carpets, fusible interlinings, and garment adhesive interlinings |
Low |
|
Ethylene-Vinyl Acetate（EVA） |
Good tack and adhesion, relatively low cost |
Used for bonding footwear, leather, and paper, with good flexibility |
Low |
|
Polyamide and Copolymer |
Wide range of properties and melting points, better heat resistance than polyethylene and EVA, but higher price, some reactive types available |
Used in garments and applications requiring solvent resistance (e.g., dry cleaning） |
Medium to High |
|
Polyester and Copolymer |
Wide performance range, high temperature resistance, good durability, high cost, some reactive types available |
Used in automotive interior parts and special applications with high requirements for heat and chemical resistance |
High |
|
Polyurethane |
Good adhesion to many substrates, good durability, good flexibility and toughness, expensive, reactive |
Used in automotive interiors, laminates for protective clothing, shoemaking, and reactive hot-melt polyurethane in structural applications |
High |
Then, what role does polyethylene wax play in hot melt adhesive systems?
Polyethylene wax acts as a viscosity modifier in hot melt adhesive systems, with the following main functions:
First, it adjusts melt viscosity. Different application processes require different melt viscosities, and the melt viscosity of hot melt adhesives can be adjusted by varying the amount of wax used to adapt to different glue application methods.
Second, it regulates curing time. The use of hot melt adhesives must align with the time requirements of the application process; otherwise, even highly viscous adhesives cannot fully exert their performance.
Additionally, the use of wax can optimize the applicability of hot melt adhesives, such as addressing stringing issues, meeting flowability and wetting requirements, and preventing caking during storage and surface stickiness.
Polyethylene wax can also be used as a dispersant in hot melt adhesives.
