Cationically curable silicone compositions based on colloidal silica and anti-mist/anti-fouling hard coatings formed therefrom

Abstract

Silicone compositions that are cationically crosslinkable into hard, anti-mist / anti-fouling coatings, e.g., onto thermoplastic substrates, contain colloidal particles of non-functionalized silica and also: at least one crosslinkable and / or polymerizable silicone monomer, oligomer and / or polymer comprising: at least one structural unit of formula (I): Z1(R0)aSiO(3−a) / 2  (I) in which: a=0, 1 or 2; the radicals R0, which may be identical or different when a >1, are each an alkyl, cycloalkyl, aryl, vinyl, or alkoxy radical, or a hydrogen atom; the radicals Z1, which may be identical or different when the number of units of formula (I) is greater than 1, are each an organic substituent comprising at least one epoxy and / or alkenyl ether and / or oxetane and / or dioxolane and / or carbonate reactive functional group; and a total number of silicon atoms per molecule at least equal to 2; and an effective amount of at least one cationic initiator; and optionally, at least one organic solvent.

Description

CROSS-REFERENCE TO PRIORITY / PCT APPLICATIONS [0001] This application claims priority under 35 U.S.C. § 119 of FR 02 / 15946, filed Dec. 16, 2002, and is a continuation of PCT / FR 2003 / 003614, filed Dec. 8, 2003 and designating the United States (published in the French language on Jul. 29, 2004 as WO 2004 / 063300 A1; the title and abstract were also published in English), each hereby expressly incorporated by reference and each assigned to the assignee hereof.BACKGROUND OF THE INVENTION [0002] 1. Technical Field of the Invention [0003] The present invention relates to compositions which can be crosslinked by the cationic route to provide hard scratch-resistant coatings. [0004] More preferably, the present invention relates to compositions which can be crosslinked by the cationic route to provide hard coatings furthermore exhibiting anti-fouling and / or anti-mist properties. [0005] 2. Description of Background and / or Related and / or Prior Art [0006] Thermoplastics, such as polycarbonate, h...

AI Technical Summary

Problems solved by technology

However, these materials also exhibit a major disadvantage, namely, their low hardness in comparison with that of glass.

Consequently, these materials are more easily subject to scratching and to detrimental changes, even in the context of normal use.

A significant disadvantage of these compositions is the time necessary for the crosslinking.

However, a disadvantage of these compositions is that of having a poorer resistance to abrasion than that of the coatings crosslinked by the thermal route.

One disadvantage of the technique described in this patent is, first, that it involves the preliminary functionalization of the colloidal silica by an alkoxysilane and, secondly, that it is necessary to remove the solvent for functionalization of the silica before carrying out the crosslinking.

The anti-mist coating obtained from the composition described in FR-A-2,749,587 has the principal disadvantage of being sensitive to inhibition by atmospheric oxygen.

However, no composition of the prior art is capable of providing a hard coating jointly exhibiting anti-mist and anti-fouling properties.

This is because the mechanisms of the anti-mist and anti-fouling properties are generally incompatible.

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