Cellulose esters have been used for decades to enhance aesthetics and improve productivity in automotive OEM applications. They enable:
- Flow and leveling, which improve gloss and smoothness
- Improved color consistency
- Metallic flake alignment, which increases brightness
- Reduced drying time, which means increased throughput and productivity
- Excellent redissolve resistance
Cellulose esters provide the ideal rheology to ensure that coating material flows evenly to provide a uniform finish and defect-free coating. Using Eastman cellulose esters greatly reduces sagging, pitting, picture framing, orange peeling, fish-eyeing, floating, flooding, crawling, and telegraphing—all problems that plague an OEM.
Eastman cellulose esters have been used for many years in coatings for various plastic materials. Cellulose esters may be used in the barrier coat to protect the plastic from attack by strong solvents in subsequent coating layers. CABs are frequently used for aluminum flake orientation. Butyrate/acrylic compositions give good results when used on ABS, acrylic, or cellulose plastics. The clear systems yield very hard, brilliant films; the pigmented systems are bright and show exceptionally good gloss retention.
CAB 551-0.01 is a good starting point for solventborne base coats. It provides robust metallic flake orientation that ensures consistent color in a wide application (temperature/humidity) window. Uniform flake orientation also results in uniform appearance of the composite coating. It is nonyellowing and has very good UV durability. This complements the excellent weathering of the composite coating system. CAB 551-0.01 can be blended with CAB 381.20 to provide good solvent strike in from the clear coat, which ensures a superior wet look and distinctiveness of image of the overall coating.
Eastman CAB-321-0.1 is recommended for automotive OEM base coats to produce excellent metallic flake alignment. Low butyryl content makes it a good choice for the base coat because it is less soluble in the solvents used to carry the topcoats and is therefore less likely to be redissolved when the topcoat is applied.
CAB-381-0.5 is a cellulose ester with medium butyryl content used in automotive base coats for metallic flake control. It was designed for use where low application viscosities at relatively high solids levels are needed. Use where lower viscosity for higher-solids formulations and increased toughness with excellent surface hardness is desired.
Eastman Solus™ 2100 and Eastman Solus™ 2300 performance additives were designed for high-solids solventborne systems to help formulators reach new heights of performance and productivity in VOC-compliant automotive OEM coatings. Unlike conventional cellulose esters, a Solus product can be formulated at 60% solids with a low level of solvent. Consequently, higher spray solids can be achieved with Solus. This gives you virtually the same benefits as conventional cellulose esters—metallic flake orientation, faster drying, consistency in color and appearance—but at higher spray solids that enable 2K VOC-compliant and high-solids paint systems to be produced. It should also be noted that Solus products can be blended with conventional cellulose esters to produce optimum performance at the desired solids.