Key points in the use of edge banding strips

Edge banding hot melt adhesive is a type of adhesive specifically used for edge banding of artificial boards. It is a solvent-free thermoplastic adhesive. When the hot melt adhesive is heated to a certain temperature, it transforms from a solid state to a molten state. After being applied to the surface of the artificial board substrate or edge banding material, it cools and turns back to a solid state, bonding the edge banding material and the substrate together.

1、Binders of Edge Banding Hot Melt Adhesives

(1) EVA (Ethylene-Vinyl Acetate Copolymer Resin) binder hot melt adhesives. This type of hot melt adhesive can be divided into two categories: filled and unfilled. Using EVA as the binder is a common production technology for edge banding hot melt adhesives, and its main limitation is poor heat resistance. The ambient temperature for using panel furniture edge-banded with EVA hot melt adhesives should not exceed 120°C.

(2) Polyamide binder hot melt adhesives. This type of hot melt adhesive has excellent heat resistance and the characteristic of rapid curing, with the main drawback being its high price.

(3) HMPU (Polyurethane) binder hot melt adhesives. They are a type of hot melt adhesive with excellent performance and guarantee high-quality board edge banding. They are expensive and require special application methods.

2、Viscosity of Edge Banding Hot Melt Adhesives

The viscosity of edge banding hot melt adhesives cannot directly reflect the quality of the adhesive's performance. Generally, the higher the viscosity of the edge banding hot melt adhesive, the better its initial bonding strength, but the poorer its coating performance. Low-viscosity hot melt adhesives require a smaller amount of application and have better wetting properties. Some low-viscosity hot melt adhesives with fast curing speeds may also have high initial bonding strength. For low-quality particleboards, it is necessary to select hot melt adhesives with higher viscosity. This is because high-viscosity hot melt adhesives have poor fluidity and, during application, are less likely to seep into the pores at the edges of particleboards compared to low-viscosity ones, ensuring that the hot melt adhesive can be fully applied to the board edges.

3、Density of Edge Banding Hot Melt Adhesives

The density of edge banding hot melt adhesives generally ranges from 0.95 to 1.6 g/cm³, and its density depends on the amount of filler (the more filler, the higher the density). Since a certain coating area is required for board edge banding, the adhesive amount per unit length of unfilled hot melt adhesives (with lower density) is less than that of filled ones. Moreover, because unfilled hot melt adhesives have better bonding performance, it is possible that a smaller amount of unfilled hot melt adhesive is needed to achieve the same edge banding effect as filled ones. To reduce the adhesive application amount, the edge banding machine must be equipped with a good gluing system.

4、Softening Point and Application Temperature of Edge Banding Hot Melt Adhesives

The softening point is an indicator of the heat resistance of edge banding hot melt adhesives. The higher the softening point, the less likely the adhesive is to melt. Additionally, the softening point is an important factor in measuring the temperature resistance of panel furniture. In Europe, there is a set of testing methods for the heat resistance of edge-banded boards, and standards for the heat resistance of panel furniture have been established. Countries such as France, Germany, and Italy no longer mass-produce edge banding hot melt adhesives with low softening points, but domestic manufacturers (including Taiwanese manufacturers) still produce and supply them to the domestic market. This is because domestic furniture manufacturers and consumers currently do not pay sufficient attention to the heat resistance of panel furniture, especially kitchen furniture. The softening point of EVA hot melt adhesives generally ranges from 90°C to 135°C.

The application temperature of hot melt adhesives refers to the temperature of the adhesive on the gluing roller of the edge banding machine. Only at this temperature can the hot melt adhesive achieve optimal bonding strength. The temperature displayed on some edge banding machines may have a significant deviation from the actual temperature, so it is necessary to regularly calibrate the machine's temperature. If the temperature of the edge banding machine is too high, the adhesive will carbonize and smoke; if it is too low, the bonding strength will decrease.

5、Open Time of Edge Banding Hot Melt Adhesives and Feeding Speed of Edge Banding Machines

The open time of edge banding hot melt adhesives refers to the period from the start of adhesive application by the edge banding machine to the moment when the edge band is pressed onto the substrate. The open time varies depending on the type of adhesive. The feeding speed of the edge banding machine is closely related to the open time, and both are crucial when selecting and using hot melt adhesives. Edge banding machines with fast feeding speeds must use hot melt adhesives with short open times; conversely, those with slow feeding speeds should use adhesives with long open times.

For most manual edge banding machines, due to manual operation by workers, the hot melt adhesive used is required to have a sufficiently long open time to facilitate edge banding of curved components. Hot melt adhesive is generally applied to the edge banding strip. To ensure the edge banding quality, domestic manual edge banding machines also adopt the method of double-sided gluing. The temperature of the glue tank of a manual edge banding machine is generally controlled below 180°C (the German BRANDT manual edge banding machine can be heated to above 200°C), so hot melt adhesives with a working temperature below 180°C should be used. If edge banding thin PVC edge strips with a thickness of less than 0.2mm on a manual edge banding machine, the working temperature of the hot melt adhesive used must be around 120°C.