Polyethersulfone (PES), a high-performance engineering thermoplastic, has long been used alone and in combination with other polymers — as the base for paint and coatings owing to its high thermal stability, chemical resistance, and surface hardness, plus superior adhesion to a variety of substrates, including glass, iron, stainless steel, aluminum, and aluminum alloys. To support the paint and coatings industry, Sumitomo Chemical Advanced Technologies LLC (here) has introduced three new PES grades to meet the needs of formulators.
SumikaExcel 4100P is the standard coating grade and 4100MP is the same material but is offered ground to a micron-powder, which enhances solubility and dispersion. A third grade, SumikaExcel 5003PS has been chemically modified to possess a large number of hydroxyl (-OH) end groups — on average 0.6-1.4 per 100 repeating polymer units — which, in turn, can be used to create cross-linked structures that further increase the material’s already-good chemical resistance, surface hardness, and adhesion to metals. That makes it ideal for use for paint and coatings requiring higher performance in more aggressive environments. For organic solventbased paints and coatings, typically formulators will select either the standard 4100P grade or — where a harder coating is needed — the functionalized 5003PS grade. For water-based paints and coatings, the 4100MP micron-powder grade is typically used owing to its finer particle size (available ground to powders with average particle sizes as fine as 15 µm) for easier mixing and dispersion in water-based solvents.
PES is an amber-transparent, amorphous engineering thermoplastic known for its high mechanical properties, including high strength and impact resistance, low creep even at elevated temperatures and loads. Additionally, it offers excellent thermal stability, including long-term heat aging and performance at elevated temperatures1 , low warpage (owing to the complete absence of crystallization), high dimensional stability, and low coefficient of linear thermal expansion (CLTE) over a broad temperature range. The polymer also provides superior stress-crack and good and broad chemical resistance2 , particularly for an amorphous thermoplastic.
Other properties of PES that are beneficial in the paint and coatings market include the material’s stability even after long periods of use in air at temperatures up to 250°C and under conditions of repeated heating/cooling cycles (from 0°C to 250°C to 0°C again); its excellent hydrolysis resistance under humid conditions or in water; its superior film-forming properties, which provide excellent adhesion as well as protection to substrate materials; its high and inherent flame retardance without need for flame-retardant additives; and its excellent transparency that does not change the appearance of the base material. Additionally, the material meets all U.S. Food & Drug Administration (FDA) requirements for food-contact applications and does not support microbial growth.
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