In flexographic printing, screen printing inks, and metal/plastic finishing industries, low-surface-energy or highly dense substrates like polyester films (PET), aluminum foil, and galvanized alloy steel sheets have long been notoriously difficult for achieving reliable ink and paint adhesion. Because these substrates lack active polar surface groups, cured inks often fail tape tests and peel off easily.

Tianjin Ruikel Chemical Co., Ltd. developed RT-3227 Adhesion Promoter, engineered specifically to dramatically boost the bonding strength of inks and coatings on PET plastic and metal surfaces. It delivers exceptional interlayer and substrate adhesion while offering core advantages such as high-temperature yellowing resistance and zero impairment to weatherability.

1. RT-3227 Core Specifications & Physical Properties

RT-3227 is a partially phosphate-esterified polyester adhesion promoter supplied as a pale yellow powder or granules with exceptionally high solid content.

Technical Specifications Table

2. Why Are PET and Metal Substrates So Hard to Bond?

• Low Surface Energy of PET Films: Lacking active polar groups, standard resins and inks struggle to wet the surface, resulting in weak intermolecular forces.

• Dense and Smooth Metal Surfaces: Substrates like aluminum foil, tinplate, and galvanized alloy steel make it extremely difficult for inks or coatings to form effective microscopic "anchoring" grips.

• Chemical Anchoring Mechanism of RT-3227: The phosphate ester groups in its molecular structure form robust chemical bonds and physical adsorption with active sites on metal surfaces (such as aluminum, iron, and zinc) as well as polar plastic surfaces, building an unbreakable "molecular bridge" between the substrate and the coating film.

3. Key Performance Advantages

1. Dramatic Adhesion Enhancement on PET & Metals: Specifically targeted for PET films, aluminum foil, printed tinplate, coil coatings, and various galvanized alloy steel sheets, significantly improving cross-hatch tape test and peel strength results.

2. High-Temperature & Weathering Resistance: Does not discolor or yellow during high-temperature baking and curing, and maintains the long-term weatherability of the coating film.

3. Excellent Resin Compatibility: Shows great compatibility with mainstream polyurethane (PU), chlorinated polypropylene (CPP), and various industrial resin systems, with zero adverse impact on storage stability.

4. Versatile Application Scopes: Ideal not only for gravure and screen printing inks but also for modifying matt varnishes, improving adhesion to PET films without compromising post-curing performance.

4. Recommended Applications & Dosage

A. Primary Application Fields

• Packaging & Printing Inks: Gravure and screen printing inks requiring superior adhesion to PET films and aluminum foil.

• Metal & Plastic Coatings: Printed tinplate coatings, can coatings, coil coatings, and composite coating systems contacting metal/PET.

• Matt Varnish Modification: Added to polyurethane (PU) matt varnishes to enhance bonding strength on PET films.

B. Usage Method & Recommended Dosage

• Recommended Dosage: Typically added at 0.5% - 2.0%$  of total formulation weight; up to 3.0% for demanding substrates. For gravure printing inks based on polyurethane or chlorinated polypropylene, a concentration of 0.2% - 0.8% is recommended.

• Precautions:

• Conduct preliminary laboratory trials to determine optimal dosage and compatibility before bulk use.

• While usable in polyurethane systems (may cause slight cloudiness, which does not affect performance), it is not recommended for alcohol-based polyurethanes or inks containing high levels of alcohol-based solvents. Minimize mixing with alcohol-based solvents during use, and keep alcohol concentrations low in the formula.

5. Summary & Sample Requests

If you frequently encounter peeling, flaking, or substandard adhesion when printing on PET or coating metal substrates, Ruike Chemical's RT-3227 Adhesion Promoter provides an economical and highly efficient solution.

To download Technical Data Sheets (TDS), Safety Data Sheets (SDS), or request free laboratory evaluation samples, visit our technical portal at www.rk-chem.com.

• Visit www.rk-chem.com to explore selection guides for RT-3227 and other coating/ink additives.

• Contact our technical application team today for tailored formulation advice and to request a free laboratory test sample!