Pressure-sensitive adhesive compositions (PSA) have been known for a long time

Pressure-sensitive adhesive compositions (PSA) have been known for a long time. PSA is an adhesive composition that allows lasting adhesion to the substrate even at relatively weak applied pressures and can be separated from the substrate again substantially without residue after use.

Psas are permanently viscous at room temperature and therefore have a sufficiently low viscosity and high viscosity that they wet the surfaces of the corresponding bonded substrates even at low applied pressures. The adhesiveness and separability of adhesives are derived from their adhesive properties and cohesive properties. A variety of compounds are suitable bases for PSA. Tape equipped with PSA (called pressure-sensitive tape) is currently used in a variety of industrial and household applications. Pressure-sensitive tape usually consists of a carrier membrane equipped with PSA on one or both sides.

There are also pressure-sensitive tapes that consist only of PSA layers and have no carrier film; these are called transfer tapes. Pressure-sensitive tape compositions can vary greatly and are guided by the specific requirements of different applications. The carrier usually consists of a plastic film such as polypropylene, polyethylene, polyester, or paper, woven fabrics, or nonwoven. Self-adhesive or pressure-sensitive adhesive compositions usually consist of acrylate copolymers, silicone (organosilicon), natural rubber, synthetic rubber, styrene block copolymers, or polyurethane. PSA may be modified by mixing a viscosifier resin, a plasticizer, a crosslinker, or a filler to formulate properties suitable for the application. For example, use fillers to improve PSA cohesion. In this case, the combination of filler/filler interactions and filler/polymer interactions often results in the desired reinforcement of the polymer matrix. Fillers are also mixed to increase the weight and/or bulk of the paper, plastics, as well as adhesives and coatings, and other products. Fillers often improve the technical availability of products and have an impact on their quality (e.g., strength, hardness, etc.).

Natural, inorganic, and organic fillers such as calcium carbonate, kaolin, talc, dolomite, etc. are manufactured mechanically. In the case of rubber and synthetic elastomers, suitable fillers may also be used to improve quality, such as hardness, strength, elasticity, and elongation. Widely used fillers are carbonate, particularly calcium carbonate, as well as silicates (calcite, clay, mica), siliceous soil, calcium and barium sulfate, aluminum hydroxide, fiberglass and glass spheres, and carbon black. Inorganic and organic fillers can also be distinguished according to their density. For example, inorganic fillers such as chalk, titanium dioxide, calcium sulfate, and barium sulfate are often used in plastics and adhesives to increase the density of compounds because they themselves have a higher density than the polymer.

The base weight is higher at the same thickness. There are also fillers that reduce the total density of the complex. These include hollow microspheres, which are very large, lightweight fillers. The ball is filled with air, nitrogen, or carbon dioxide; The shell of the ball consists of glass or, in the case of some products, thermoplastic. Especially in the case of automotive applications, plastic is increasingly used instead of metal. These plastics often have low surface energy, which makes bonding with these substrates more difficult. Moreover, adhesive bonding should be as stable as possible against aging and heat. Products used to date are mainly based on acrylates (stable to aging, but not well adhered to surfaces with low surface energy (called LSE surfaces), SBC synthetic rubber (well adhered to LSE surfaces, but not heat resistant), or natural rubber (well adhered to LSE surfaces, but not stable to aging). LSE surfaces specifically include PVA, polystyrene, PE, PP, EVA, or Teflon. However, programs that combine all good qualities are still lacking.