Wood Furniture Building elements
Professional article

Dispersions at work – versatile and trusted wood adhesives

Since their development in the 1950s, dispersion glues have become the ideal partner for the wood and furniture industry as well as for woodworking shops. And while today there are also alternative solutions, like PUR hot melts, available for several fields of application, the tried-and-trusted and often specialised “all-rounders” continue to impress due to easy processing, outstanding bonding results and very high cost-effectiveness. Jowat, the adhesives specialist from Detmold, supplies a comprehensive range of PVAc dispersions and foil bonding adhesives for virtually any application in the wood and furniture sector as well as for ship interiors.

“From floors to ceiling panels and from interior finish to furniture. We have the right dispersion at the ready for almost any application, no matter what durability class under EN 204/205 is needed or what the requirements are regarding heat resistance, viscosity, assembly time or pressing time,” says Maik Johanntoberens, Product Manager at Jowat SE. Jowat regularly carries out market assessments for the enterprise’s product developers to ensure that the product range stays up to date and meets the needs of the market. Jowat’s dispersion development lab for the wood and furniture division impresses due to a highly efficient batch formulation process, their own measurement chambers to ensure emissions are low in the early development stages already, as well as extended manufacturing levels, including their own polymerisation unit for manufacturing base dispersions. All dispersions are not equal, as a look at the different fields of application reveals.
Dispersions for floors
Whether laminates, engineered wood, design floors or solid wood – long durability is a key requirement for the adhesives used in the manufacture of flooring materials.
Modern reactive dispersion adhesives are particularly suited for the manufacture of flooring materials like engineered wood or laminates. Due to small application amounts, short pressing times, a flexible bondline and a wide variety of possible application methods, dispersions provide a solution for many different production processes. The dispersions are available in a broad range of viscosities for the most diverse application methods and surface properties. Depending on the use and requirements for the floor, the portfolio provides adhesives from D3 dispersions according to EN 204/205 for interior applications with short-term water exposure or high humidity to D4 dispersions for interior applications with very high requirements regarding moisture resistance.
For the highly popular design and vinyl floors, Jowat supplies powerful dispersion-based foil adhesives. Floors have a big emission potential due to large surface they cover. Therefore, making sure that emissions from the adhesives are as low as possible is a key objective. The latest vinyl acetate copolymer dispersions from the Jowacoll® series are free of plasticisers and solvents and still provide high adhesion to the substrates to be joined. For Jowat, emission limits are much more than just another requirement for a standard or quality seal. The adhesives manufacturer sees them as an opportunity to play an active role in facilitating a healthy indoor environment.
Solutions for building elements
Adhesives used in window scantlings and doors (fire doors, sound-proof doors, apartment doors, front doors) usually have to meet highest requirements due to the special functions and structures of the end product and to the conditions to which it will be exposed during use. A comprehensive portfolio of powerful D4 dispersions and EPI dispersions helps processors meet the different requirements.
Manufacturers of window scantlings and door frames have to adhere to strict regulations, for instance by the ift Rosenheim (“Institut für Fenstertechnik”), that also apply to the adhesives used. Laminated window scantlings and door frames are mostly manufactured with PVAc glues that meet the requirements for durability class D4 according to EN 204. If those bonded products are intended for exterior use, they must be protected by an adequate surface coating. Moisture-resistant bonds require special reactive one- and two-component D4 dispersions. That latest generation of reactive dispersions provide substantial advantages compared to other technologies like the UF resins widely used in the past. They have a very low formaldehyde content, therefore meeting the requirements for a “pollutant-free” indoor environment, can be applied in significantly lower amounts, and provide a more flexible bondline. In addition, they facilitate a gluing at room temperature and the pressing of joined parts in hot presses can be done at considerably lower temperatures, therefore reducing energy consumption.
For interior doors, manufacturers generally use special PVAC dispersions based on formulations that have been optimised for the lamination of decor papers and films as well as thermoplastic foils and which meet the requirements for durability class D3.
Two-component EPI (emulsion polymer isocyanate) adhesives have been tried and tested in applications that require durability class D4, in particular joints that are exposed to direct weathering, bended laminates and modified wood. Compared to reactive dispersions, EPI adhesives provide a much higher solids content and are characterised by fast curing and high resistance to heat and moisture.
Diversity in furniture production
In the furniture industry, manufacturers primarily use classic wood and assembly glues as well as lacquer glues. PVAc dispersion adhesives are mainly used for assembly operations. The special formulations used for this purpose facilitate very short pressing times. Lacquer glues today are expected to join not only highly resistant surfaces coated with UV lacquers or SH lacquers, but also different metal surfaces, synthetic resin like melamin, and even glass. Two adhesives from Jowat’s Jowacoll® series meet the entire range of requirements for lacquer glues. This makes adhesive handling significantly more convenient, especially for smaller woodworking shops.
In the modern industrial production of furniture and wood-based materials, carrier boards are coated with different surfaces. Due to digital technology, the variety in designs is virtually unlimited. To ensure superior results, manufacturers use dispersions developed specially for flat laminating applications. The adhesive portfolio ranges from veneer glues to foil adhesives with optimum viscosity, and from dispersions with a high solids content to dispersions with very high green strength.
Specialised adhesives are also used for dowelling. Due to reduced stringing, the PVAc dispersions can be applied by nozzle on fully automated production lines and join hardwood as well as softwood species and wood-based materials. The product range includes low-viscosity, process-optimised adhesives for a horizontal application by automatic dowelling machines, as well as paste-like adhesive formulations for vertical upside-down processing on assembly lines.
Fire protection in ceiling panels and in shipbuilding
Laminating adhesives used in ceiling elements, for instance cement-bound ceiling panels used for sound insulation, also have to meet strict fire safety requirements. The PVAc surface glues used in those applications have been optimised to meet the requirements for fire safety and therefore support the flame-retarding properties of the composite elements.
In shipbuilding, even stricter regulations apply. Especially with regard to fire safety and durability. For those applications, Jowat supplies high-performance adhesives with “low flame-spread” characteristics that are marked with the IMO “wheelmark” of the International Maritime Organization (IMO).
Service makes the package complete
When it comes to dispersion glues and their optimum use in different applications, Jowat is a supplier with a hands-on approach and many decades of experience. The adhesives specialist from Detmold has the right solution up its sleeve for even special requirements like in shipbuilding or in high-frequency bonding. The commitment to a perfect gluing solution, however, goes far beyond offering a range of products, as Maik Johanntoberens explains: “Only by coupling our powerful, optimally adapted dispersions with a comprehensive service and close contact with the processor can we live up to our high quality standard in adhesive applications over the long run.”

The article is published in the magazine "HK 6/2019" in German language. You can download the original article down below.