Carbon Nanotube-Based Curable Coating Composition Providing Antistatic Abrasion-Resistant Coated Articles

Abstract

The present invention relates to a curable composition, providing, upon curing, an abrasion-resistant, transparent, antistatic coating, comprising carbon nanotubes and a binder comprising at least one epoxysilane compound, preferably an epoxyalkoxysilane, and optionally fillers such as nanoparticles of non electrically conductive oxides and / or additional binder components such as tetraethoxysilane. The invention further relates to optical articles comprising a substrate, and, starting from the substrate, an abrasion- and / or scratch-resistant coating, and an antistatic coating formed by depositing directly onto said abrasion- and / or scratch-resistant coating the above referred curable composition. The obtained optical articles exhibit antistatic properties, high optical transparency with about 91-92% of transmittance, low haze and improved abrasion resistance.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to curable compositions for preparing transparent antistatic abrasion-resistant coatings, articles exhibiting antistatic and abrasion-resistance properties coated therewith, in particular optical and ophthalmic lenses for eyeglasses, and a process to prepare such articles.[0003]2. Description of Related Art[0004]It is well known that optical articles, which are essentially composed of insulating materials, have a tendency to get charged with static electricity, especially when they are cleaned in dry conditions by rubbing their surface with a cloth or synthetic piece, for example a polyester piece (triboelectricity). The charges which are present at the surface of said optical articles create an electrostatic field capable of attracting and fixing, as long as the charge remains on optical articles, objects lying in the vicinity thereof (a few centimeters) that have a very little weight, gen...

AI Technical Summary

Benefits of technology

[0019]An object of the invention is to provide novel curable coating compositions capable of imparting antistatic and abrasion resistance properties to an article, especially a transparent and low haze article, and overcoming the problems and disadvantages associated with current CNT-based compositions.

[0020]Another object of the invention is to provide electrically conductive coatings providing antistatic properties, having low haze and excellent scratch and / or abrasion resistance at the same time.

Problems solved by technology

It is well known that optical articles, which are essentially composed of insulating materials, have a tendency to get charged with static electricity, especially when they are cleaned in dry conditions by rubbing their surface with a cloth or synthetic piece, for example a polyester piece (triboelectricity).

ITO is the industry standard antistatic agent to provide optically transparent electrically conductive thin coatings, but the performance of ITO suffers when it is applied to plastics.

These coatings are fragile and are readily damaged during bending or other stress inducing conditions.

Conductive polymers represent the most investigated alternative to ITO coatings, but they still cannot match the optical and electrical performances of ITO and sometimes suffer from thermal and environmental stability problems in specific applications.

However, they are still in their infancy and raise a lot of challenges, such as low loading percentage in polymer systems.

However, it is difficult to make such CNT-based film with good quality on curved surfaces, which limits its application in ophthalmic lens industry.

Although the films having a layer of CNT exhibit light transmittance of about 90-92% at the wavelength of 550 nm and small changes in sheet resistance after having been subjected to an abrasive treatment, the CNT layer show potential high haze after a spray process, due to the absence of binders or surfactants in the CNT dispersion, which is not investigated.

The above-mentioned electrically conductive or antistatic coatings have shown very promising performances, but still have limitations with the process, their transparency, or haze values, which prevent them from some specific applications, especially in ophthalmic lens application.

In addition, no antistatic coating has been reported to increase abrasion resistance.

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