Polyurethane Adhesives

Polyurethane systems are materials that facilitate our lives today by being used in many fields and are present in our living spaces. Adhesive family polyurethane-based products are actively used in many sectors from automotive to construction, from footwear to furniture. Polyurethane adhesives are compounds that adhere carefully to different materials and possess strength and durability properties that give them strong resistance to both water and solvents once permanently hardened.

Polyurethane-based products have the following advantages over general adhesives;

• Flexibility advantage despite rigid structure, • Good adhesion resistance on different structures, • Fast cure time, • Ability to react at low temperatures, • Good chemical and oil resistance. For good adhesion, there are multiple parameters. The materials to be bonded and the adhesives must have certain properties. • Surfaces must be clean, • Physical or chemical treatment must be applied to the surfaces to be bonded, • The adhesive to be used must have suitable physical and chemical properties, • Application conditions must be suitable (parameters such as temperature and humidity). In the bonding process, the interaction between the surface and the adhesive and the strength resulting from the molecular structure of the adhesive are important. We can explain this chemically as follows. The effect resulting from a substance's surface layer showing properties similar to a flexible layer is called "surface tension." We can say that a contact angle is formed at the point where the adhesive substance comes into contact with the surface. If there is a large contact angle, it indicates the scarcity of liquid-solid attractive forces, and if there is a small contact angle, it indicates that these forces are large. Based on this data, as the angle increases, we can say that it becomes difficult for the adhesive to wet the surface, meaning adhesion may be weak.

In the bonding process, if an adhesive is used, we frequently hear the terms adhesion and cohesion. Adhesion is explained as the sum of forces that enable two surfaces to be bonded.

On a microscopic scale, the two surfaces to be bonded approach each other to a certain distance, and within this distance range, adhesive molecules are observed to enable bonding on all surfaces. Cohesion, on the other hand, is the attractive force between molecules of the same type. For example, the attractive forces between adhesive or water molecules are referred to as cohesion. The resistance of bonded materials to external influences and their resistance to deformation depend on the magnitude of cohesive forces. In light of this information, Kobe Polyurethane's adhesive group, which shapes its work according to customer needs, provides different advantages. Rubber binder with low usage properties provides advantages in usage quantity and mold opening time for use in hot or cold molds, while in-place cast rubber binder provides ease of application in addition to the excellent adhesion strength it provides. Panel group adhesives provide one-component and two-component products for different applications in batch or continuous production. These product groups suitable for all types of surfaces provide the advantage of homogeneous distribution and consumption. For bonding shredded sponges, these are one-component systems with low viscosity and high adhesion strength with excellent surface adhesion properties. Due to its low viscosity characteristics, it also allows spray application. Filter adhesives offer fast or slow cure alternatives and provide high resistance to chemicals and heat. These solvent-free products are used in filter applications such as automotive, heavy equipment, electric vacuum cleaners, and compressors, as well as in bonding plastic products.

In addition to the product groups mentioned;

• Marine adhesives, • Automotive adhesives, • Furniture group adhesives, • Construction group adhesives, • Industrial adhesives with quick solutions When contacting Kobe Polyurethane for more information, suitable systems will be provided according to application specifications. Gülhan Sarıgöl R&D Engineer Kobe Polyurethane References • I.R. Clemitson, Castable Polyurethane Elastomer • M. Lonescu, Chemistry and Technology of Polyols for Polyurethanes • M. Szycher, Szycher's Handbook of Polyurethanes • U. Eichert, Journal of Coated Fabrics, vol. 24, July, 1994, • Advances in Polyurethane Technology, Eds., J.M. Buist and H.A. Gudgeon, Maclaren and Sons, London, UK,1968. • www.adhesiveandglue.com