The benefits of reactive PUR hotmelts in surface lamination

Surface lamination is a process used in various industry sectors to bond plastic films, decor papers, HPL, CPL, etc., to the surfaces of different materials.

Furniture manufacturers and furniture suppliers typically laminate MDF and chipboard panels as well as lightweight panels (sandwich elements) made from plastic and aluminium. Sandwich elements are often laminated to make pieces of furniture, car parts, and in ship and boat building.

Decor papers are made of plastics, natural fibres, and varnished systems, and available in all kinds of designs, with and without embossments, and in different qualities. There is a huge choice of laminated boards available for furniture elements and flooring.
The adhesive joins the decor and the carrier material, and therefore plays a key role in the quality of the surface lamination. Kitchen and bathroom fittings, for instance, are constantly exposed to heat and moisture, but expected to have a long service life. Floors also have to withstand mechanical wear and tear over many years. The choice of adhesive impacts both the quality and durability of the lamination. Reactive polyurethane adhesives have revolutionized surface lamination and opened up a multitude of new opportunities.

EVA and PVAc adhesives have a high water content, so the carrier material has to be absorbent in some way. This limits their scope of use to a certain degree. Wood-based materials are generally very absorbent, while plastics and metals are not. Reactive PUR adhesives do not contain any water and have excellent bonding properties to several materials, such as wood-based and mineral materials and plastics.

Water-based adhesives can cause irreversible swelling of the decor surface, which is particularly undesirable for high-gloss decors – any unevenness impacts the super-smooth mirror effects. This will not happen when using PUR adhesives. Once the glue has hardened, the adhesive layer will not distort in any way.

EVA and PVAc glues have only limited resistance to strong temperature fluctuations and moisture, so the glue joints will begin to deteriorate over time. Reactive PUR hotmelts, however, react chemically to form a tightly cross-linked elastomer or duromer, which creates an immensely strong and durable bond. Reactive PUR hotmelts currently generate the best and most long-lasting adhesive bonds possible.

Streamlined manufacturing processes are key to the industry. Laminating machines that use PVAc or EVA adhesives have relatively long cycle times, or need complex process technology to keep cycle times short. The laminated materials can only move on to the next processing stage once all the moisture has evaporated from the glue joint and/or the glue has formed its film.

This is where the benefits of reactive PUR hotmelts shine through. Short cycle times and direct further processing of the laminated material contribute to efficient processes. The high initial strength of a PUR adhesive and easy application with heated rollers and slot nozzles also speed up the manufacturing process. These methods require customizable PUR hotmelts. Depending on the material combination and process technology, the formulation of the adhesive can be adjusted to production specifications such as the application temperature, melting viscosity, open time, and the initial and final strength.

KLEIBERIT has a long tradition of intensive research and development. We are committed to producing more sustainable products and we have invested considerable research into reactive PUR adhesives containing plant-based and sustainable raw materials that are not suitable for food production. Users can therefore expect the same level of quality in surface lamination – i.e. excellent bonding performance and coordinated production processes – as our conventional reactive PUR hotmelts provide. With the right know-how, it is possible to reduce the level of petroleum-based raw materials used.