Catalysts are used to improve abrasion resistance of coatings
General strategies of increasing crosslink density by use of higher-functionality oligomers and/or larger amounts of crosslinking agents have been used to improve abrasion resistance. To get the higher crosslink density, catalysts are sometimes added to the paint formulation as additives in small quantities.
Catalysts are additives that will increase the rate of a -chemical reaction but are not consumed or changed in the reaction process. Catalysts have widely varying compositions that depend on the nature of the reaction being catalyzed. Many of the crosslinking reactions used to form durable films are accelerated by the use of catalysts. For example, melamine crosslinked systems, polyurethanes and epoxies make use of catalysts.
Acid catalysts (and blocked acid catalysts) are used to accelerate the reaction between the crosslinking resin and the primary resin. Good crosslinking is desirable so that the final cured film will show improved properties. By increasing the molecular weight of the crosslinked product, improvements are gained in scratch and mar resistance, corrosion resistance and film hardness. Typical acid catalysts used in coatings are: dinonyl naphthalene disulfonic acid (DNNDSA), dinonyl naphthalene sulfonic acid (DNNSA), dodecyl benzene sulfonic acid (DDBSA), para-toluene sulfonic acid (PTSA) and alkyl acid phosphate (AAP).
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