In our everyday lives, we are always surrounded by adhesive joints, and we are often unaware that the vast majority of items we use every day are only feasible thanks to adhesives. In the household, the spectrum ranges from flooring and furniture to electronics and even hygiene articles.
Adhesives have become an indispensable part of our lives and have replaced conventional mechanical connections such as plug-in, screwed and welded joints.
An almost unlimited choice of adhesives
As diverse as the possible applications of adhesives are, the specific requirements of the various processes are equally varied. It is self-explanatory that the packaging industry, medical engineering, and the electronics sector require different adhesive properties for their respective products. Therefore, there cannot be a universal super adhesive because the respective demands of the different industries and application areas are too diverse and often contradictory.
Depending on the product, debondable, non-debondable or conditionally debondable joints are preferred. Within the same sector, different manufacturing and adhesive application processes necessitate the use of certain types of adhesives with specific properties.
Durability and resistance
Manufacturers in all sectors of industry are constantly on the lookout for suitable adhesives that meet the highest demands. For example, in surface finishing as well as in the production of composite materials, the furniture industry relies on durable and resistant adhesive bonds to produce high-quality products.
In particular, products that are installed in wet rooms, such as bathrooms or kitchens, are often exposed to extreme temperature fluctuations and humidity.
Manufacturers of windows, as well as entrance and patio doors, see their products permanently exposed to seasonal weather conditions, which confronts them with the seemingly insoluble challenge of avoiding premature ageing and damage through the highest product quality.
The solution is advanced adhesive technology
Thanks to its broad adhesion spectrum, i.e., the ability to process a wide range of different materials, one type of adhesive comes closest to being a universal superglue. It is used, among others, in the automotive industry, in window production as well as in the textile sector but also in bookbinding and shipbuilding and many other processes. We are talking about reactive polyurethane hot melt adhesives (HMPUR), which have become the industry standard in recent decades.
These are one-component and solvent-free adhesives that are melted before processing and then applied in liquid form. On cooling, they already develop a very high initial strength, which, among other advantages, enables a continuous, linear production process without the use of static presses.
What is the difference from other hot-melt adhesives?
In addition to reactive PUR adhesives, vinyl- or polyolefin-based adhesives, which also belong to the family of hot melt adhesives, are used as alternatives. PUR adhesives, however, are distinguished by a decisive feature that is responsible for the excellent adhesive properties. While EVA and PO adhesives can be re-melted by subsequent application of temperature, PUR hot-melt adhesives offer irreversible bonding. This is because, in addition to the physical bonding, a chemical reaction takes place with water, which is available once as atmospheric moisture as well as in the processed materials. This creates a tightly cross-linked elastomer that has excellent water and temperature resistance for a long-lasting and resilient bond.
A technology in continuous development
PUR hot melt adhesives have established themselves as the best choice for permanent bonding in a wide variety of applications and can be used in almost unlimited combinations of materials. A major advantage is that in the final product they are completely emission-free and do not release any formaldehyde or other harmful substances. In addition, this adhesive technology has undergone significant further development in recent years. As a result, adhesives with a monomeric isocyanate content of less than 0.1% are available today. These so-called “micro-emission adhesives” are therefore not subject to the labelling requirements of the Hazardous Substances Ordinance. Likewise, materials from bio-based sources are increasingly being used for production in order to permanently reduce the use of fossil raw materials and enable the entire supply chain to improve its carbon footprint.
How do I find the right PUR hot melt adhesive?
This technology involves professional industrial adhesives that are not usually available for private use in DIY stores.
Reactive PUR hotmelt adhesives are developed, produced and distributed by specialised companies.. . It is important to note that within this adhesive segment, individualised solutions are offered for the respective production needs. It is therefore advisable to seek expert advice in advance and to test the adhesive extensively.
TAKA is a leading company specialising in reactive PUR hotmelt adhesives, which offers free consultations as well as employee training on process optimisation and quality improvement.
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