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Primer and adhesion promoter systems

TRAPYLEN® and TRAPUR® are primer and adhesion promoter systems for coating, bonding, printing and laminating polyolefinic plastics.

Depending on the application, TRAPYLEN® and TRAPUR® are ready-to-use products or adhesion-enhancing additives.

Painting of molded plastic parts

Refinement of foils

Applications:

Veredelung von Folien

Adhesive additives for printing inks

The base polymers for our products are mainly

  • Chlorinated polyolefins (CPO)
  • Chlorine-free modified polyolefins (APO)
  • Polyurethane (PU)

Our products are available as

  • Solid resins
  • Polymer solutions in organic solvents
  • Aqueous dispersions
  • UV-crosslinkable liquids

The use of adhesion promoters

Primers are generally used when substrates that are difficult to coat are to be bonded, painted or coated in some other way. It is also incorrectly referred to as a primer, but this is not the case when painting plastic. The effectiveness of the adhesion promoter is defined by its adhesive strength, i.e. the measure of the resistance of a coating to mechanical separation from the substrate. There are several standardized DIN and ISO norms for testing adhesion promoters. By increasing the adhesion strength, paints are given improved resistance to chemicals and other environmental influences, for example. Primers are used in many applications nowadays; so-called functionalized silanes or other organometallic compounds (titanates or zirconates) are often used in glass coating. The coating of plastics, especially polyolefins, is a particular challenge for an adhesion promoter. Polypropylene [PP] or polyethylene [PE] are used in automotive engineering, e.g. for vehicle bumpers.

Polypropylene or polyethylene are used in automotive engineering, e.g. for vehicle bumpers. For design reasons, the bumper is often painted in the color of the vehicle. As a pre-treatment, this molded part is coated with a modified polypropylene (e.g. chlorinated polypropylene or acrylate-modified polyolefin) as a primer (sometimes also plastic adhesive). Chlorinated polypropylene (CPO) in particular has been used in a variety of applications over the last forty years, such as in the Film coating or as Additives for the printing ink industry. This results in a variety of delivery forms of chlorinated polyolefins, e.g. a solid resin can be dissolved directly in a printing ink.

Alternative processes to an adhesion promoter would be corona pre-treatment, plasma pre-treatment or flame treatment. Corona pre-treatment is also used for film coating in particular to ensure that the coating to be applied wets the substrate optimally.
The disadvantage of this pre-treatment is that the surface tension of the excited surface decreases over time. The use of flame treatment is extremely difficult or often not possible at all, especially when using flammable solvent-based paints or varnishes, due to the open flame.

 

Our product recommendations and technical advice are based on careful research and are given to the best of our knowledge, but are non-binding. They do not release the user from carrying out his own tests to determine the suitability of our products for the respective applications.

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