Transparent plastic optical components and abrasion resistant polymer substrates and methods for making the same

Abstract

A polymer-based component formed from a synthetic thermoplastic or thermoset resin substrate, such as polymethyl methacrylate, which is resistant to warping and distortion from moisture. A composite multi-layer surface-hardening coating is formed on at least the anterior surface of the resin substrate. The component can include a composite multi-layer reflective coating to form a mirror. A protective back-coat layer is deposited on a posterior surface of the mirror. A multi-layer weather-resistant coating may optionally be applied to the anterior surface of the polymer-based mirror in order to increase the weatherability and durability of the mirror. The various layers coating the synthetic resin substrate have their moisture permeabilities selected so that substantially equal amounts of moisture permeate through to both the anterior and posterior side of the synthetic resin substrate. A sol-gel coating can be used to deposit the multi-layers in a single step by providing gradient zones of zirconia / silica while enabling a hydrophobic or a hydrophilic exterior surface.

Description

RELATED APPLICATIONS [0001] This application is a continuation-in-part of U.S. patent application Ser. No. 10 / 177,614, filed on Jun. 24, 2002, now issued as U.S. Pat. No. 6,601,960, which is a continuation-in-part of U.S. patent application Ser. No. 09 / 916,777, filed Jul. 27, 2001, now issued as U.S. Pat. No. 6,409,354, which is a conversion of U.S. Provisional Patent Application Ser. No. 60 / 227,194, filed Aug. 23, 2000.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates generally to coated plastic substrates such as polymer-based optical components including window panes and mirrors, and specifically to lightweight and durable synthetic resin optical components resistant to abrasion and warpage and methods for the manufacture thereof. [0004] 2. Description of Related Art [0005] Coated plastic substrates and optical components are commonly used in various applications. The use of lightweight plastic substrates are frequently desirable bu...

AI Technical Summary

Benefits of technology

[0013] A reflective layer of a composition substantially resistant to moisture is deposited on the posterior side of the resin element. The reflective layer comprises a series of materials sequentially deposited onto the posterior surface of the treated resin substrate. A reflective layer formed from the following layers exhibits the desired reflectance, moisture permeability, and durability for the polymer-based mirror of the present invention: 500 to 1200 angstroms of SiO, preferably 750 angstroms; 700 to 1500 angstroms of aluminum, preferably 1200 angstroms; 500 to 1200 angstroms of SiO, preferably 750 angstroms; 600 to 1400 angstroms of Zv(iPv)2, preferably 725 angstroms; and 300 to 1200 angstroms of SiO2, preferably 550 angstroms. The reflective layer of the invention is preferably formed on the synthetic resin substrate via a vacuum deposition technique. A protective back-coat layer is then deposited over the reflective layer to encase the outer surface of the reflective film layer. When the surface-hardening layer is also applied to the posterior surface of the resin substrate, the back-coat layer can also encase the surface-hardening layer as well as the reflective layer. A weather-resistant coating is further applied to the anterior surface of the polymer-based mirror in order to increase the weatherability and durability of the mirror.

[0014] Overall, the polymer-based mirror of the present invention has a multilaminate configuration including sequentially deposited layers of organic and inorganic materials. The polymer-based mirror of the present invention exhibits superior moisture resistance as compared to conventional aluminum, chromium, and rhodium coated mirrors. The present invention further provides a mirror that is easily and economically produced.

[0015] Another embodiment of the present invention provides an improved resin substrate component such as a mirror or window for the automotive industry or any application of a resin substrate component with superior abrasion resistant properties that can be made in an economical manner. A gradient coating of a zirconia / silica colloid particles can be provided directly on a synthetic resin substrate by a sol gel method of coating the substrate and permitting a controlled orientation and migration of the zirconia / silica colloid particles within a polysiloxane carrier before curing. As a result, the resin substrate is provided with layers or gradient zones having varying amounts of zirconia / silica colloid particles. In one embodiment, the exterior surface of the final product will have a high concentration of zirconia / silica particles to provide an abrasion resistant and moisture stable product that can accommodate thermal expansion cycles during normal use. The present invention further includes the method of making such a product.

Problems solved by technology

The use of lightweight plastic substrates are frequently desirable but have presented problems for long-term use.

The main problem associated with synthetic resin mirrors is their significantly limited operational service life resulting from warpage or distortion of the mirrors due to the hygroscopic properties of thermoplastics or thermoset resins.

Over time, the moisture so absorbed corrodes the reflective layer.

Furthermore, the moisture permeability of the various coatings applied to both sides of the synthetic resin substrate often lead to different amounts of moisture being absorbed by the opposing surfaces of the synthetic resin substrate, thus resulting in uneven expansion and contraction on both sides of the substrate.

These conditions all interact to produce distortion to the image produced by the reflective layer of the plastic mirror and a related loss of optical clarity.

Although organosilicon polymers are the best available material for this purpose, these polymers are not totally impermeable to water.

Thus, although partially effective, these polymers do not provide a complete remedy to all of those issues related to the use of a thermoplastic or thermoset resin substrate material in connection with a mirror apparatus.

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