Acrylate resin

Acrylate resins are a large family of plastics built on acrylic acid. What they share is a reactive carbon-carbon double bond at the end of each molecule. Give it a nudge with UV light, heat or a chemical starter, and those double bonds open and link into chains or networks within seconds.

To make them, acrylic acid is usually first combined with alcohols to make esters, such as butyl acrylate, or attached to larger molecules to make oligomers with several reactive ends. The choice of building blocks decides whether the result is soft and sticky or hard and glassy. UV-curing grades get a photoinitiator. Some are polymerized at the factory, like adhesives; others are sold as liquids and harden only once in place.

Because they cure fast and clear, they turn up all over a TV:

• the binder in color photoresist that hardens into the color filter's windows;
• the tiny prisms on a prism sheet and the bead coating on a diffuser sheet;
• the adhesive that sticks each polarizer to the glass;
• the light-patternable part of solder mask on circuit boards.

A close relative, methyl methacrylate, makes acrylic (PMMA), the clear plastic sold as Plexiglas.