RAUKANTEX pure edging is applied to the cut edge of the board using hot-melt adhesives.
To ensure the joint holds and looks neat, there are four key factors to consider:
• good adhesive coverage of the edge and panel
• stable processing temperature
• sufficient contact pressure
• the right adhesive for the material and process

RAUKANTEX edging is applied using so-called hot-melt adhesives – usually EVA or PUR. Both systems have their strengths, depending on the application.

EVA adhesives are based on thermoplastic raw materials and cure as they cool. They are easy to work with and can be reactivated by heat. However, under high temperatures – for example, in the kitchen – this can cause the adhesive joint to come apart again.

Once applied, PUR adhesives react chemically with moisture in the air and cure permanently. This results in particularly strong bonds that are highly resistant to heat, moisture and chemical influences. It cannot be reactivated at a later date, which ensures that the joint remains stable in the long term.

Regardless of the adhesive system chosen, the following applies: to ensure a secure, high-quality bond, it is essential to ensure good wetting of the materials, the correct temperature control, sufficient contact pressure and clean surfaces.

Practical tip: When using EVA adhesives, it is advisable to clean the glue pot and the machine whenever there is a change in colour (e.g. from light to dark) to prevent any visual defects.

EVA hot-melt adhesives are typically used at processing temperatures of 180–210 °C and are considered to be tolerant of machine downtime. PUR hot-melt adhesives are applied at lower temperatures of around 100–150 °C and require controlled cleaning of the adhesive systems.

When using PUR adhesives, the REACH restriction on diisocyanates must also be observed within the European Union. For PUR adhesives containing ≥ 0.1% by weight of monomeric diisocyanate, mandatory isocyanate training has been required for industrial and commercial users since 24 August 2023. This training requirement does not apply when using monomer-reduced PUR adhesives with a residual monomer content of less than 0.1% by weight.

In the case of EVA hot-melt adhesives, a distinction is made between filled and unfilled variants, which differ in both their processing characteristics and the appearance of the bond.

'Filled EVA adhesives contain mineral fillers that stabilise the flow properties and ensure smoother application.' This helps to reduce thread tension, particularly at lower feed rates, and ensures a uniform application.

Unfilled EVA adhesives are made from pure resins and allow for a very fine application of the adhesive. The result is particularly narrow joints, whilst using less material. However, this requires appropriately coordinated processes, in particular higher feed rates and precise machine settings.

The RAUBOND range offers suitable solutions for both requirements – tailored to the specific application and process environment.

Hot-melt adhesives are applied in various container formats, depending on the type of machine and application system. The most common method involves using granules, which are melted in a glue pot. Alternatively, depending on the machine and adhesive system, cartridges or, in the case of PUR adhesives, block adhesive may also be used.

The choice of container shape has a direct impact on handling during operation, the effort required for cleaning, and process reliability during processing.

The feed rate directly affects the open time of the adhesive and the wetting of the substrates.
The faster the feed rate, the quicker the adhesive needs to set.

In addition to the set target temperature in the glue pot, the actual temperature at the application point is particularly important.
Important: The sheet material should be at room temperature before use. Cold boards cool the adhesive too quickly and reduce its adhesion.

Common causes include:
• adhesive temperature too low
• insufficient pressure at the first pressure roller
• soiled surfaces