40 times more durable! Latest anti-reflection film technology

Unparalleled durability with the AR Film HD-Series

In July 2020, Dexerials developed the AR Film HD-Series, an anti-reflection film with an anti-smudge layer on the top surface, formed by a vacuum deposition method. HD-series AR Films that reveal a 40-fold increase in abrasion resistance compared to conventional products. Below will describe the background behind its development.

Dexerials’ anti-reflection films exhibit low reflectivity (glare) when applied to displays such as laptops and in-vehicle displays.  Sputtering technology is used to form a metal oxide layer on the surface with nano-level precision. Its surface has an anti-smudge layer made of fluorine resin to make it easy to wipe off fingerprints and other stains.

One important function required of the anti-smudge layer is that it must withstand physical force such as wiping or rubbing. The displays of smartphones, touchscreen laptops, and tablets are frequently touched or rubbed with fingers or stylus pens. Each time this happens, the anti-reflection film on the surface is subjected to frictional force, which may cause small, invisible scratches. As those scratches accumulate, the anti-smudge layer may deteriorate, making it easier to leave fingerprints on the surface, or the anti-reflection film may peel off, resulting in poor visibility.

Furthermore, in order to make laptops lighter and thinner, there has recently been an increase in products that substitute the cover glass with anti-reflection film. Customer demands for even more durable in-vehicle displays have also increased. Therefore, it has become necessary to further improve the durability of the anti-smudge layer of anti-reflection films.

Issues in using the “wet” process to form the anti-smudge layer

Standard Dexerials’ anti-reflection film uses a method known as the “wet” method to form the anti-smudge layer on the topmost surface. The following is a diagram of this method.

The anti-smudge layer of anti-reflection film is made of fluorine resin. In the “wet” method, a solution containing an anti-smudge agent is applied to the surface of the substrate on which the anti-reflection layer is formed. The solvent is evaporated by the heater to then form the anti-smudge layer. The anti-smudge agent exhibits high abrasion resistance because the reactive groups of silicon on the surface of the anti-reflection layer and the fluorine resin polymers that make up the anti-smudge agent are bound by ‘siloxane bonds’, which are strong chemical bonds similar to the molecular structure of glass and quartz. However, this method comes with a problem. The reactive groups of the anti-smudge agent do not face the silicon side of the anti-reflection layer, which inevitably means there are areas where they do not bond properly.

Advantage of the vacuum deposition method

In contrast, in the newly developed technology by Dexerials, the anti-smudge layer is created on top of the anti-reflection layer through a method called vacuum deposition. The following is a diagram of the method.

The material used for the anti-smudge layer in the vacuum deposition method is the same fluorine resin used in the “wet” method, but instead of applying it directly, it is evaporated by heating it to a high temperature and deposited on the surface. The process is performed in a vacuum chamber to prevent surface contamination. This method allows the reactive groups to be oriented toward the anti-reflection layer and be uniformly aligned, resulting in a denser and stronger bond than in the “wet” method.

This newly developed anti-reflection film with an anti-smudge layer maintains the same excellent optical characteristics as the standard product, such as 0.5% or less reflectance and over 95% transmittance. It also has 40 times higher abrasion resistance than the standard product.

Excellent performance demonstrated in abrasion resistance tests

Below is a graph showing the results of abrasion resistance tests conducted on the AR Film HD-Series manufactured using the vacuum deposition method and the standard product manufactured using the “wet” method. The tests were performed by repeatedly rubbing the surfaces with a non-woven fabric wiper and observing the contact angle of water droplets on the surfaces.

For the standard product, the water contact angle became less than 100° after 500 abrasion cycles, and dropped to less than 90° after 2000 cycles. This means that the water on the surface of the product spreads, making it more susceptible to stains. In contrast, the product made using the vacuum deposition method achieved an initial water contact angle of 120° and maintained a contact angle of 110° even after 20,000 abrasion cycles, indicating that it easily repels water and has high anti-smudge performance.

Dexerials commercialized the newly developed AR Film HD-Series in the spring of 2021. Now that remote work has become common due to COVID-19, there is an increasing demand for touchscreen laptops and tablets. Dexerials’ AR Film HD-Series is a direct response to this trend. Dexerials’ is committed to continue development of products that respond to changes in the world.