Primer and adhesion promoter systems
TRAPYLEN® and TRAPUR® are primer and adhesion promoter systems for painting, bonding, printing, and laminating polyolefin plastics.
Depending on the application, TRAPYLEN® and TRAPUR® are either ready-to-use products or adhesion promoter additives.
Applications:
Applications:
Applications:
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
- Water-based dispersions
- UV-crosslinkable liquids
The use of adhesion promoters
Polypropylene or polyethylene are used in automotive manufacturing, for example, for the vehicle’s bumper. For design reasons, the bumper is often painted to match the color of the vehicle. As a pretreatment, this molded part is coated with a modified polypropylene (e.g., chlorinated polypropylene or acrylate-modified polyolefin) as a primer (sometimes also referred to as a plastic adhesive). Chlorinated polypropylenes (CPO), in particular, have been used in a wide range of applications over the past forty years, such as in film coating or as additives for the printing ink industry. This has resulted in a wide variety of forms in which chlorinated polyolefins are supplied; for example, 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.
FAQ: The Use of Adhesion Promoters
Adhesion promoters, also known as primers, help ensure the long-term adhesion of paints, adhesives, printing inks, or other coatings to substrates that are difficult to coat.
What is an adhesion promoter, or primer?
A adhesion promoter is a pretreatment that improves the bond between the substrate and the subsequent coating. It is primarily used when plastics, films, glass, or other surfaces that are difficult to coat are to be painted, bonded, printed on, or laminated.
Is a primer the same thing as a base coat?
Not necessarily. When it comes to painting plastics, “adhesion promoter” or “primer” is usually the more precise term. While a primer can serve various functions, the primary purpose of an adhesion promoter is to improve adhesion between the substrate and the coating.
How is the effectiveness of a adhesion promoter assessed?
Adhesion strength is crucial. It describes a coating’s resistance to mechanical separation from the substrate. Standardized test methods based on DIN and ISO standards are available for this purpose. Good adhesion can also improve the resistance of the entire coating system to chemicals and environmental influences.
Which materials are particularly challenging?
Polyolefin plastics such as polypropylene (PP) and polyethylene (PE) are particularly challenging. PP/EPDM blends and GMT are also among the substrates that are difficult to paint. They are found, among other things, in automotive components such as bumpers.
How are plastic bumpers prepared for painting?
Before painting, the molded part can be treated with a primer based on a modified polypropylene, such as chlorinated polypropylene (CPO) or an acrylate-modified polyolefin. This improves the adhesion of the subsequent coat of paint.
What types of chemical systems are used in adhesion promoters?
TRAMACO offers primer and adhesion promoter systems based on chlorinated polyolefins (CPO), chlorine-free modified polyolefins (APO), and polyurethanes (PU). Depending on the application, both chlorinated and chlorine-free solutions are available.
In what forms are adhesion promoters available?
Adhesion promoters are available as solid resins, polymer solutions in organic solvents, aqueous dispersions, or UV-curable liquids. The appropriate form depends on the substrate, coating system, and application process.
How are primers applied to plastic molded parts?
For molded parts, a polymer primer can be applied directly from the solution. Alternatively, it can be formulated with binders and pigments to create a pigmented primer. TRAMACO offers both solvent-based and water-based standard products for this purpose.
What role do adhesive brokers play in film finishing?
For TPO membranes, ready-to-use primers are used to enable or improve subsequent painting. According to TRAMACO, the typical solid resin application rate for a membrane primer ranges from 0.5 to 5 g/m².
How do adhesion additives support printing inks?
For solvent-based printing inks used on PP and other polyolefins, adhesion additives can be incorporated directly into the ink. They enhance adhesion to the plastic. Adhesion-enhancing additive systems are also available for UV-curable printing inks.
What alternatives are there to a bail bondsman?
Possible alternatives include corona pretreatment, plasma pretreatment, and flame treatment. In film coating, corona pretreatment improves, in particular, the wetting of the substrate by the coating being applied.
What are the limitations of COVID-19 and flame treatment pretreatments?
Surface activation achieved through corona or plasma treatment may diminish over time. Flame treatment is often difficult or impractical for flammable, solvent-based paints and varnishes due to the open flame.
Does a product recommendation replace your own evaluation?
No. The suitability of a primer depends, among other things, on the substrate, pretreatment, coating or adhesive system, application method, and operating conditions. Therefore, the application should always be tested under the specific process conditions of the user.