Лако-красочные материалы — производство

Because of the relatively higher resin costs, process improvement evaluations are replacing unit or batch cost considerations. Many of the new coatings and adhesives provide down­stream benefits, which, when factored into the overall cost of manufacturing, equal or reduce cost as compared to traditional coating technologies.

For example, a highly filled epoxy resin, for potting wires into a board connector, represents about one or two cents of the total component cost. The cost associated with mixing, heat curing, handling, and cooling hot pats adds about five cents to the assembly process cost. Finally, cost associated with downstream quality control and rejected parts adds, conservatively, another two or three cents.

Alternatively, the newest generation of structural adhesives adds up to four-six cents material cost per component. The material’s high efficiency and quality, however, lower assembly and quality costs. A company saves as much as 30-50% in overall component manufacturing cost and achieves a dramatic reduction in rejects.

Similarly, a 70% solvent-based or water-based conformal coating solution might cost as little as half of a solvent-free curing alternative. The energy expense to remove water, however, is high. The economic and environmental penalties to remove solvents are even greater. New OSHA and EPA regulations are expected to further restrict solvent usage. The seemingly prime disadvantage of infrared and UV alternatives are further offset when one considers that up to 70% of the lower-priced coatings can be lost to evapora­tion.

The automotive industry leads the way in harsh environmental use of consumer electronics. Electronics represents over 10% of current costs to car makers. Much of the costs is for sensing and controlling components.

Because conventional UV resins cure only when exposed to UV light, resin underneath components will not cure and is unacceptable for automotive use. The aerobic UV coatings have a unique secondary heat curing ability (as low as 85°C), which makes them attractive. Simply raising the temperature of the boards for 5 min allows the uncured resin to ‘‘shadow cure.’’

One major automobile manufacturer was concerned about the use of urethane coatings with regard to solvent safety and emissions regulations. The cost and size of the complex coating supply and solvent evaporation equipment were other issues. Also, a 2 hr oven time limited the type of board it could coat and presented a severe handicap to short-run production and just-in-time delivery systems.

The company now sprays an aerobic coating onto the board. Because there are no solvents, boards move immediately beneath a high-intensity UV light for just 5 s. Short-run production is no longer a problem.

As we have suggested, aerobic adhesive technology has proven remarkably well suited to cures effected by UV light. Aerobic acrylics cured by UV light have the potential for vastly broadening the market for acrylic adhesives.

As previously discussed, UV potting compounds used to be limited by their inabil­ity to cure through more than several mils. For larger gaps (most potting projects), slower curing epoxies have been the sole option for many manufacturers. Now, however, fast curing UV aerobic acrylic adhesives can pot depths of several inches in areas accessible to UV light.