Optically transparent pressure sensitive adhesive

Modern display devices contain organic components that are susceptible to UV degradation, especially if they are exposed to outdoor environments or in close proximity to fluorescent black lights and/or other short wavelengths. Degradation is seen in the display as a color shift or faded appearance.

UV radiation is divided into three bands: UV C(below 280nm), UV B(280-320nm), and UV A(320-390nm). To minimize degradation, display devices need to protect all three bands. UV barriers such as the cover glass on a display block UVC emission. To minimize UVB radiation in LCD displays, a displaced device is usually sealed with UV-blocking glass paint. A large portion of the UVA range (320-390nm) passes through the front of the LCD. This UV A degradation can show fading changes, cracks, or disintegration in everyday objects when exposed to sunlight for long periods of time.

Display units usually consist of multiple layers bonded to each other and sealed to prevent degradation and escape of moisture. An optically transparent adhesive (OCA) film is used to bond the layers in a display device, including the cover glass, touchpad, and other layers, to fill the air gaps between the different layers of the display and to improve the image quality and durability of the display.

Usually, there is at least one OCA film in any LCD or LED display. Although the display device uses some type of UV barrier in the device, such as UV barrier cover glass, plastic film, and coating; Very little work has been done on the manufacture of optically transparent adhesives (OCAs) with UV blocking. An OCA layer of solution polymerization including a UV-blocking adhesive layer is disclosed in US 2013/0321991; However, the program has a number of shortcomings.

The OCA layer of the solution polymerization shrinks during UV curing, thus unsticking the substrate. In addition, an uneven layer of adhesive is produced where the edges of the adhesive are thinner than the center. Ink compositions and methods relating to UV blocking inks for transparent substrates are disclosed in US 2003/0109599. Although ink compositions prevent UV transmission, they do not have the adhesive properties to bond the substrate together.

In the power domain, there is still A need for optically transparent adhesive films for display electronic devices that have high optical transparency in the visible range while blocking the transmission of a significant percentage of harmful UV A, B, and C radiation for extended periods of time.