Liquid, optically clear adhesives (LOCA) provide superior optical enhancement and anti-glare properties in the manufacture of liquid crystal displays. The design of LOCA adhesives must take into account long-term exposure to environmental conditions such as light, temperature, humidity, and mechanical shock. Resin Designs chemists have devised a family of products for both screen face adhesion and edge sealing that have been fully tested to assure clarity and adhesion are maintained over time.
Let’s take a deeper look at the way chemists test for various exposure conditions.
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Reliability Testing Using Q-SUN Xenon Arc Testers
Light, temperature, and moisture can significantly affect the physical and visual properties of adhesives, leading to yellowing, discoloration, delamination, and loss of adhesion. Test chambers can use thermal shock, humidity-controlled, and xenon arc lamps to understand the effect of these exposures on adhesives’ stability. However, the synergistic effect of these exposures is more damaging than individual factors alone.
This is a job for Q-SUN xenon arc testing, which allows studying the cumulative effect of sunlight exposure, humidity, high temperature, and thermal shock. Xenon arc weathering tests using Q-SUN testers select specific wavelength spectra controlled temperature and humidity conditions based on product specifications and their intended use.
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Radiation exposure:
Q-SUN xenon arc testers can replicate the full sunlight spectrum including ultraviolet, visible, and infra-red. There is also the feasibility of using optical filters to narrow down exposure wavelengths based on adhesive chemistry and field application.
Full-spectrum of Q-SUN xenon arc lamp with daylight filter
Heat Exposure:
Q-SUN test chambers allow for controlled temperature conditions in the chamber. The effect of sunlight exposure is more aggravated by heat. In real-time applications, displays get heated when being in use for a longer time. Displays in Marine, while being hot, may simultaneously be exposed to sunlight and humid conditions. With Q-SUN test chambers, these exposure conditions can be replicated while also having leverage to control the temperature. The advantage of controlled temperature conditions allows for selecting conditions based on adhesive chemistry and display design.
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Humidity exposure:
To replicate natural moisture conditions, humidity is created by water spray or controlled relative humidity conditions. The combination of humidity and temperature allows the creation of thermal shock conditions since humidity tries to cool down the material (which is at high temperature). The combination of water spray and light can effectively simulate exposure conditions for displays used in agricultural equipment.
Conclusion
Long-term retention of properties, most importantly clarity and light transmission, is critical to the design and manufacture of LCD display assembly adhesives. Resin Designs scientists have extensive experience as well as the latest in testing equipment and methods to measure these properties and simulate extended aging. This experience and technical acumen can provide peace of mind and assurance for OEMs regarding expected warranty conditions.
Chase Corporation, Westwood, Ma. Founded in 1946 is a leading manufacturer of industrial products for high-reliability applications with a global customer base operating in diverse market sectors. Our Resin Designs specializes in the design and manufacture of specialty polymers for adhesion protection of assemblies in industries such as automotive, white goods, aerospace, electronics, and more. Our outstanding manufacturing and technical support groups can provide your organization with a reliable global supply, unmatched quality, and superior technical support.
Please contact us today to discuss your application.
