Decorative coating in addition to a hard base coat

Abstract

The present disclosure relates to a method for preparing a coated plastic article, the method comprising: a. providing a plastic substrate having at least a first and a second surface; b. depositing a decorative coating comprising a layer of a metal or a metal alloy on the plastic substrate using physical vapor deposition; and c. applying a protective coating to at least the first surface of the plastic article, wherein there is no plasma pretreatment of the plastic substrate prior to deposition of the decorative coating. Furthermore, the present disclosure relates to a coated plastic article comprising: a plastic substrate having a first and a second surface, a decorative coating comprising a layer of a metal or a metal alloy deposited directly on the plastic substrate and a protective coating applied to the first surface of the plastic article, wherein the residual stress of the decorative coating is tensile and the coated plastic article passes the SAE J2527 accelerated UV test.

Description

[0001] Cross-reference of related applications

[0002] This application claims priority to Australian Provisional Patent Application No. 2021900071, filed on January 14, 2021, which is incorporated herein by reference in its entirety for all purposes. Technical Field

[0003] This invention relates to decoratively coated plastic substrates, which provide plastic articles. The plastic articles of this invention possess sufficient elasticity and abrasion-resistant properties for use in automotive applications, such as for providing interior trim and components. In particular, this invention relates to an improved method for preparing plastic articles and plastic articles prepared by such method. Background of the Invention

[0005] As more technologies are integrated into automobiles, the demand for materials used is increasing. With arrays of sensors and display elements increasingly integrated into vehicles, there is a growing need for materials that are aesthetically pleasing or mimic the appearance of traditional materials but offer improved versatility and compatibility with the components underneath.

[0006] The result is an increased use of both external and internal plastic components. Plastic components possess many attractive properties, including fracture resistance, low cost, light weight, moldability and formability, and, in some applications, transparency. However, such plastic components do not necessarily meet the visual and abrasion requirements of automotive applications. By coating a plastic substrate, components can be provided that meet the desired visual aesthetics while also improving the abrasion resistance of the underlying plastic substrate.

[0007] A range of techniques for applying thin-film coatings to plastic substrates have been developed. These techniques, such as physical vapor deposition, aim to provide thin-film coatings to the first or second surface of a plastic substrate. However, the coefficient of thermal expansion of the deposited film (especially metal and metal alloy films) is often an order of magnitude different from that of the plastic substrate, making the film on the plastic substrate susceptible to damage and cracking during use. This is particularly problematic in applications such as vehicles where internal and external components are exposed to harsh conditions, high UV light, and relatively high temperatures. Therefore, to prevent film damage, it is important to regulate the stress at the interface between the deposited decorative film coating and the substrate and to promote strong adhesion between the plastic substrate and the deposited film coating.

[0008] To achieve strong adhesion, plastic substrates (e.g., polycarbonate) are often pretreated to improve surface properties such as roughness (see, for example, S Pelagade et al. 2010 J. Phys.; Conf. Ser. 208; 012107). An important pretreatment is plasma pretreatment (see Pelagade et al. 2010 – ibid.; Seidel C et al. 1999 Appl. Surface Sci. 150, pp. 19–33; Hofrichter A et al. 2002, J. Vacuum Sci. & Tech. A 20, pp. 245–250; Hegemann D et al. 2003, Nucl. Instrum. & Meth. B., 208, pp. 281–286; Boldyryeva H et al. 2004, Nucl. Instrum. & Meth. B., 219–220, pp. 953–958; and Kitova S et al. 2005, J. Optoelectronics and Advanced Materials, 7, pp. 2607–2612). Plasma pretreatment has a range of effects on plastic substrates, including modified surface roughness, modified surface polymer groups, and increased surface energy (and wettability). Thus, plasma pretreatment offers many advantages, improving the adhesion between the plastic substrate and the subsequently deposited film, and is a fundamental and routine step in depositing the film onto the plastic substrate.

[0009] The generation of plasma also produces ultraviolet (UV) radiation. Exposure of the plastic substrate to UV radiation causes degradation of the outermost exposed surface of the plastic substrate. This degradation can subsequently cause cohesive failure at the substrate-coating interface, especially when the coated plastic article is exposed to additional UV light during use. This failure is due to the fact that the deposited coating is inevitably thin and therefore allows light to pass through. This means that UV exposure during use can penetrate the decorative coating and interact with the underlying substrate. This UV radiation exposure of the substrate can lead to damage—or further damage in the event of prior UV exposure—particularly at the upper surface of the substrate that interacts with the decorative coating, thereby causing cohesive failure.

[0010] To prevent UV radiation damage to plastic substrates, it is essential to apply a protective base coating to the substrate prior to plasma pretreatment. This protective base coating reduces UV light transmission during plasma pretreatment and also acts as an intermediate layer to regulate stress between the substrate and the applied film coating. However, the use of a protective base coating adds significant time and cost to the manufacturing process. Furthermore, the base coating fills in and smooths variations and textures in the substrate. While this is necessary in some cases, it is problematic in others because it prevents the formation of visual textures in plastic articles. Therefore, there is a need for a lower-cost and more efficient method for preparing plastic articles with decorative coatings that can pass durability tests for applications such as automotive. Invention Overview

[0012] This invention provides a method for preparing decoratively coated plastic articles, whereby the plastic substrate does not require a protective coating before the deposition of the decorative coating, while still maintaining sufficient durability for automotive applications. Therefore, this invention provides an improved method for preparing plastic articles. In some embodiments, this invention also allows for the inclusion of subtle visual textures in the substrate.

[0013] In particular, the present invention provides a method for preparing a coated plastic article, the method comprising: (a) providing a plastic substrate having at least first and second surfaces; (b) depositing a decorative coating comprising a metal or metal alloy layer on the plastic substrate using physical vapor deposition; and (c) applying a protective coating to the first surface of the plastic article, wherein there is no plasma pretreatment of the plastic substrate prior to the deposition of the decorative coating. In some preferred embodiments, the decorative coating is deposited on at least the first surface of the plastic substrate, and the protective coating is applied directly to the decorative coating.

[0014] The use of plasma pretreatment is standard practice in the industry to promote adequate adhesion between the deposited coating and the plastic substrate. However, as discussed in this paper, the UV radiation generated during this process can damage the plastic substrate and therefore necessitates the earlier application of a protective base coating, which also modulates the stress at the interface between the substrate and the deposited coating.

[0015] However, in some embodiments of the invention, the decorative coating is deposited directly onto the plastic substrate without the need for a protective coating (e.g., Momentive PHC587B or AS4700F) first applied to the plastic substrate. In these embodiments, the metal or metal alloy layer is in direct contact with the plastic substrate and thus acts as both a visual layer (providing a metallic appearance) and a protective layer for the substrate. Furthermore, the deposited metal or metal alloy layer promotes adhesion of subsequent layers in the decorative coating. The metal or metal alloy layer absorbs and reflects most light, including UV light, thus protecting the underlying substrate from subsequent exposure to UV light that may occur during use or when additional layers of the decorative coating are deposited. Additionally, in some preferred embodiments, the metal or metal alloy layer acts as the primary stress-controlling layer of the decorative coating and is in contact with the substrate. In some embodiments, additional layers may be deposited at the interface with the substrate, between the metal and metal alloy layers. These layers may provide additional optical properties (e.g., blocking light transmission or adjusting the color of the decorative layer) or control the overall residual stress of the decorative coating.

[0016] Since the decorative coating is in direct contact with the plastic substrate (in some embodiments), and because no plasma pretreatment is performed to enhance adhesion, maximizing the adhesion between the decorative coating and the plastic substrate is crucial. This can be achieved by controlling the residual stress of the decorative coating. Therefore, in some embodiments, the decorative coating is deposited under conditions that result in tensile residual film stress.

[0017] Residual stress within the film can be measured and is typically reported as pressure (e.g., MPa). It can also be reported as displacement, representing the amount of deformation of the underlying substrate after coating application. Displacement is determined by the stress within the coating, the coating thickness, and the properties of the underlying substrate. Therefore, a thicker coating with a lower stress distribution (e.g., measured in MPa) can exert the same stress displacement on the substrate as a thinner coating with a higher stress distribution. Thus, in some preferred embodiments, the residual stress of the decorative coating is measured as stress displacement. In some embodiments, a glass slide is used as the substrate to measure stress displacement. In some embodiments, the thickness of the glass slide is approximately 150 μm.

[0018] In some embodiments, the decorative coating is deposited under conditions that result in a residual film stress displacement of less than or equal to -50 μm during deposition. In some other embodiments, the decorative coating is deposited under conditions that result in a residual film stress displacement of less than or equal to -240 μm during deposition. In some still embodiments, the decorative coating is deposited under conditions that result in a residual film stress displacement of less than -765 μm during deposition.

[0019] The decorative coating of the present invention includes a protective coating that, upon use, forms the foremost coating of the prepared plastic article. Therefore, the protective coating is exposed to the elements. In embodiments of the invention in which the decorative coating is provided to a first surface of the substrate, the protective coating is deposited directly on the decorative coating and protects the underlying coating. In some alternative embodiments, the decorative coating is provided on a second surface of the plastic substrate, and the protective coating is provided to the first surface, thereby protecting the underlying plastic substrate. However, in some embodiments, the decorative coating is applied to both a first and a second side of the plastic article, thereby covering the opposing surfaces of the decorative coating and the plastic substrate. In some embodiments, the protective coating encapsulates the decoratively coated plastic substrate.

[0020] In some embodiments, the protective coating is a hard coating. In some embodiments, the protective coating is a UV-blocking coating. In some embodiments, the protective coating is Momentive PHC587B or AS4700F.

[0021] Decorative coatings comprising a metal or metal alloy layer may also include additional layers that can adjust the properties of the decorative coating. In such embodiments, the decorative coating may comprise a “stack” of layers of different materials. For example, the additional layers may adjust the total residual stress of the decorative coating, alter the visual appearance of the decorative coating, or promote adhesion of the decorative coating to subsequent treatments or layers such as the aforementioned protective coating. Therefore, in some embodiments, the decorative coating also includes an adhesion control layer (also referred to herein as an adhesion promoting layer). In some embodiments, the decorative coating also includes an optical modification layer.

[0022] In some embodiments, the optical modification layer and / or adhesion-promoting layer is the outermost layer of the decorative coating. Thus, in some embodiments, this layer interacts directly with the provided protective coating and is the first visible layer. Therefore, it is advantageous to have a transparent optical modification layer and / or adhesion-promoting layer for some embodiments. In some embodiments, the optical modification layer and / or adhesion-promoting layer are the same layer.

[0023] In some embodiments, the optical modification layer and / or the adhesion promoting layer comprises silicon. In some embodiments, silicon is deposited in the presence of oxygen. In some embodiments, the deposited optical modification layer and / or adhesion promoting layer is silicon dioxide.

[0024] In some embodiments, the metal or metal alloy of the decorative coating includes chromium (Cr), aluminum (Al), titanium (Ti), nickel (Ni), molybdenum (Mo), zirconium (Zr), tungsten (W), silicon (Si), niobium (Nb), tantalum (Ta), vanadium (V), cobalt (Co), manganese (Mn), silver (Ag), zinc (Zn), indium (In), germanium (Ge), tin (Sn), and mixtures thereof; and their oxides, nitrides, borides, fluorides, or carbides, and mixtures thereof. In some embodiments, the metal or metal alloy is selected from chromium (Cr), zirconium (Zr), aluminum (Al), titanium (Ti), germanium (Ge), indium (In), copper (Cu), cobalt (Co), and / or molybdenum (Mo). Other metals or metal alloys are also suitable. In one embodiment, any mixture of the aforementioned metals or metal alloys may be used.

[0025] In some embodiments of the invention, the metal or metal alloy layer comprises chromium. In some embodiments, the metal or metal alloy layer comprises zirconium. In some embodiments, the metal layer is composed of chromium. In some embodiments, the metal layer is a mixture of chromium and zirconium. In some embodiments, the atomic ratio of chromium to zirconium is 197:3.

[0026] It is desirable to allow selective light to pass through the coated plastic article. Therefore, in some embodiments, the method further includes providing a mask to the plastic substrate to provide a portion of controlled light transmission. The mask can be provided on a second surface or on a first surface of the substrate beneath the decorative coating. The mask may comprise a translucent coating (PVD, ink, or varnish), an adhesive mask film, a film-embedded molding, or a two-component injection molding. Thus, this can provide visual symbols within the prepared plastic article that can be illuminated by backlighting.

[0027] The advantage of not using a protective coating on the interface surface between the plastic substrate and the decorative coating is that the fine undulations and textures in the substrate are not smoothed out during the application of the protective coating. Therefore, the plastic substrate can be textured before the decorative coating is applied, resulting in a textured decorative coating. This texture is thus visible in the final plastic article. This allows for a wider range of designs to be integrated into the plastic article. Therefore, in some embodiments, the plastic substrate provided prior to the deposition of the decorative coating contains a visible texture. In some embodiments, the method further includes providing a visible texture to the plastic substrate. In some embodiments, the plastic substrate is provided with or contains two or more visually distinct textures.

[0028] Compared to other substrates such as glass or metal, the use of plastic substrates further enhances design freedom. A particular advantage of plastics is their moldability and molding properties. Therefore, in some embodiments, the plastic substrate is injection molded, has been injection molded, or is formed from a plastic capable of being injection molded. One such suitable plastic is polycarbonate. Therefore, in some embodiments, the plastic substrate is polycarbonate.

[0029] Importantly, this invention provides for the preparation of sufficiently resilient plastic articles for use in automotive applications. Particularly important is the ability to withstand damage and delamination due to UV light exposure. Therefore, in some embodiments, the methods described herein can produce articles that pass the SAE J2527 accelerated UV test.

[0030] This disclosure also provides a coated plastic article comprising: a plastic substrate having first and second surfaces, a decorative coating comprising a metal or metal alloy layer deposited directly on the plastic substrate, and a protective coating applied to the first surface of the plastic article, wherein the residual stress of the decorative coating is tensile, and the coated plastic article passes an accelerated UV test according to SAE J2527.

[0031] In some embodiments of plastic articles, the residual film stress displacement of the decorative coating is less than or equal to -50 μm, or less than or equal to -240 μm, or less than or equal to -765 μm.

[0032] In some embodiments, the protective coating on the coated plastic article is a hard coating and / or an ultraviolet blocking (absorbing or reflecting) coating. In some embodiments, the protective coating is Momentive PHC587B or AS4700F.

[0033] In some embodiments, the coated plastic article includes a visible texture on the plastic substrate. In some embodiments, the coated plastic article includes a variety of different visible textures.

[0034] In some embodiments of coated plastic articles, the metal or metal alloy layer is in direct contact with the plastic substrate.

[0035] In some embodiments of the coated plastic article, a protective coating is provided on the surface of the article having a decorative coating. In some embodiments, a protective coating is provided on the opposing surfaces of the surface having the decorative coating and the plastic substrate. In some embodiments, the protective coating covers only the surface of the article opposite the decorative coating. In a later embodiment, the decorative coating is a second surface coating, and thus the protective coating protects the first surface of the substrate and the decorative coating is visible through the substrate.

[0036] In some embodiments of the coated plastic article, the metal or metal alloy layer comprises chromium. In some embodiments, the metal or metal alloy layer comprises chromium (Cr), aluminum (Al), titanium (Ti), nickel (Ni), molybdenum (Mo), zirconium (Zr), tungsten (W), silicon (Si), niobium (Nb), tantalum (Ta), vanadium (V), cobalt (Co), manganese (Mn), silver (Ag), zinc (Zn), indium (In), germanium (Ge), tin (Sn), and mixtures thereof; and their oxides, nitrides, borides, fluorides, or carbides, and mixtures thereof. In some embodiments, the metal or metal alloy layer comprises zirconium (Zr), aluminum (Al), titanium (Ti), germanium (Ge), indium (In), copper (Cu), cobalt (Co), and / or molybdenum (Mo). In some embodiments, the metal alloy is chromium and zirconium.

[0037] In some embodiments of the coated plastic article, the decorative coating further comprises an adhesion control layer and / or an optical modification layer. It should be understood that the adhesion control layer and the optical modification layer may be the same material or the same layer. In some embodiments, the optical modification layer and / or the adhesion promoting layer is transparent. In some embodiments, the optical modification layer and / or the adhesion promoting layer comprises silicon. In some embodiments, the optical modification layer and / or the adhesion promoting layer comprises silicon dioxide.

[0038] In some embodiments, the plastic article is provided with a mask to allow a portion of controlled light to pass through. In some embodiments, this portion of controlled light passing through forms a symbol.

[0039] In some embodiments of the plastic article, the plastic substrate has been injection molded or formed from a plastic capable of being injection molded. In some embodiments, the plastic substrate is polycarbonate.

[0040] Systems comprising plastic articles prepared as described herein or by methods herein are also provided, as well as lighting systems for backlighting at least a portion of the plastic articles. Such systems are particularly envisioned for use with embodiments of the invention having a portion of controlled light transmission.

[0041] Brief description of the attached diagram

[0042] This document discusses embodiments of the invention with reference to the accompanying drawings, which are not to scale and are intended only to help explain the invention. Furthermore, the examples provided herein are not intended to limit the scope of the invention as described, but rather to disclose specific embodiments of the invention.

[0043] Figure 1 UV damage to polycarbonate is shown, as evidenced by yellowing due to exposure to plasma pretreatment.

[0044] Figure 2This demonstrates the interaction between voltage and airflow in influencing the tensile stress of the deposited chromium and zirconium alloy films.

[0045] Figure 3 An embodiment of the present invention is described, comprising a substrate, a single layer of chromium and zirconium, and a protective coating.

[0046] Figure 4 The embodiments of the present invention are described, which include a substrate, a monolayer of chromium and zirconium, a silicon dioxide layer, and a protective coating.

[0047] Figure 5 The present invention describes an embodiment comprising a substrate, a decorative coating stack comprising two chromium and zirconium alloy layers alternating with two silicon dioxide layers, and an outer protective coating.

[0048] Figure 6 An embodiment of the invention with a back-lit symbol is described. The plastic article comprises a substrate having a second surface mask and a first surface decorative coating and an outer protective coating comprising a single layer of chromium and zirconium.

[0049] Figure 7 This section describes an illustrative method for determining the stress displacement (µm) of a decorative coating.

[0050] Detailed description

[0051] Throughout this specification, reference will be made to layers relating to the plastic substrate and layers related to each other. Therefore, the following terminology will be used to define the spatial relationships between the coating and the substrate, and the spatial relationships between the layers included in the coating.

[0052] "First side" should be understood as the side of the substrate, coating, or specific layer that faces the external environment during use. In the specific case of a vehicle, this would be the visible surface.

[0053] "Second side" should be understood as the side opposite to the first side. In the context of use, this is the side facing inwards and away from the external environment. Typically, the second side is not visible when using plastic products.

[0054] "First surface" should be understood as the surface on the first side of the substrate, coating, or specified layer.

[0055] "Second surface" should be understood as referring to the surface on the second side of the substrate, coating, or specified layer.

[0056] This invention provides a method for preparing coated plastic articles, and also provides coated plastic articles. Specifically, a method is provided comprising: (a) providing a plastic substrate having first and second surfaces; (b) depositing a decorative coating comprising a metal or metal alloy layer onto the plastic substrate using physical vapor deposition; and (c) applying a protective coating to the first surface of the plastic article, wherein there is no plasma pretreatment of the plastic substrate prior to the deposition of the decorative coating. The decorative coating may be applied to at least the first surface of the substrate or at least the second surface of the plastic substrate. However, it is preferred that the decorative coating is a coating on the first surface. According to the invention, one or more metal or metal alloy layers may be applied.

[0057] While the coated plastic articles according to the invention can be used in any application, one envisioned application is for automotive uses, particularly for automotive interiors where design freedom and visual finish are important. As those skilled in the art will understand, automotive interiors are frequently exposed to high temperatures (>50 degrees Celsius) and UV light. Thus, these interior components need to be sufficiently durable to withstand such conditions.

[0058] Such temperatures and exposure to UV light can be problematic for plastic products, especially those coated with thin metal or metal alloy coatings. Typically, metal or metal alloy coatings have a coefficient of thermal expansion an order of magnitude smaller than that of the plastic substrate. Therefore, in the absence of sufficient adhesion between the plastic substrate and the decorative coating, the coating can fail, leading to cracking and delamination. Consequently, exposure of the plastic substrate to UV light, especially before the deposition of the metal or metal alloy layer, can result in poor coating performance.

[0059] UV radiation degrades plastics typically used for automotive purposes, such as polycarbonate. When exposed to UV light, the first surface of the plastic substrate degrades, and this can lead to cohesive breakdown between the substrate and the applied coating, especially when the coated article is further exposed to UV radiation (see U. Schulz et al., Applied Optics, Vol. 47, No. 13, pp. C83-C87, 2007; C. Lee et al., Thin Solid Films, Vol. 295, pp. 122-124, 1997; and E. Liston et al., Journal of Adhesion Science Technology, Vol. 7, pp. 1091-1127, 1993).

[0060] As a standard, physical vapor deposition (PVD) methods pretreat plastic substrates with a plasma beam to improve some surface properties. However, the use of plasma pretreatment also exposes the plastic substrate to UV light. When using transparent polycarbonate, this leads to yellowing of the polycarbonate (see A. Rivaton, Polymer Degradation and Stability, Vol. 49, pp. 163-179, 1995; A. Rivaton et al., Polymer Photochemistry, Vol. 3, pp. 463-481, 1983; A. Rivaton et al., Polymer Degradation and Stability, Vol. 75, pp. 17-33, 2002; and A. Rivaton et al., European Polymer Journal, Vol. 38, pp. 1349-1363, 2002). This... Figure 1 The data shows that the yellowing intensity (YID) increases with each plasma pretreatment cycle. Typically, 12 cycles of plasma pretreatment are used before coating the plastic substrate.

[0061] To prevent damage from UV radiation, a protective coating is applied to the plastic substrate prior to plasma pretreatment. This blocks UV radiation generated during plasma treatment, thus taking advantage of the benefits of plasma pretreatment without UV degradation. However, this coating and pretreatment significantly increase the time and cost of the coating method. The present invention abandons plasma pretreatment, thereby eliminating the need to apply a protective coating to the plastic substrate before coating, while still meeting the durability requirements for use in automotive applications, particularly for automotive interiors.

[0062] The substrate used in this invention can be any suitable substrate intended for use in plastic articles. However, the preferred plastic substrate is a synthetic polymer, such as: acrylonitrile-ethylene-styrene (AES), acrylonitrile-butadiene-styrene (ABS), acrylonitrile-styrene-acrylate (ASA), polyamide (PA), polybutylene terephthalate (PBT), polycarbonate (PC), polyethylene (PE), polyethylene terephthalate (PET), poly(methyl methacrylate) (PMMA), polyoxymethylene (POM), polypropylene (PP), polyurethane (PU), polyvinyl chloride (PVC), high-flow AES, acrylonitrile-(ethylene-propylene-diene)-styrene (AEPDS), a blend of thermoplastics, or a PC-ABS blend of thermoplastics. In some embodiments, the substrate is polycarbonate.

[0063] Ideally, the substrate is formed in its desired shape prior to the deposition of the decorative film. In some embodiments, a substrate formed in the desired shape is provided. In other embodiments, the method of the present invention includes shaping or molding the substrate. For example, the substrate may be injection molded prior to the application of the decorative coating.

[0064] Decorative coatings comprising layers of metal or metal alloys can be applied to a plastic substrate using any suitable physical vapor deposition (PVD) method. For example, one or more layers of the decorative coating can be deposited via thermal evaporation, electron beam evaporation (with or without ion beam assistance), sputtering deposition, pulsed laser deposition, cathodic arc deposition, or electrohydrodynamic deposition. Sputtering deposition is a preferred method.

[0065] The composition of the metal or metal alloy layer will be selected by a technician based on the desired physical and visual properties of the coating. Different metals or metal alloys have different stress distributions, and the technician can determine these and adjust the residual stress of the coating (and any respective layers) to fall within the stress displacement range of the present invention. In some embodiments, the metal or metal alloy includes one or more of the following: chromium (Cr), zirconium (Zr), aluminum (Al), titanium (Ti), germanium (Ge), indium (In), copper (Cu), cobalt (Co), or molybdenum (Mo). In some embodiments, the metal or metal alloy comprises one or more of the above.

[0066] However, in some embodiments, the metal or metal alloy coating comprises chromium or an alloy of chromium. In some embodiments, the metal alloy includes zirconium. In some embodiments, the metal alloy contains zirconium. In some embodiments, the metal is chromium. In some embodiments, the metal alloy is chromium and zirconium. In some embodiments, the metal alloy contains chromium and zirconium. In some embodiments, the concentration of zirconium in the alloy is 10% or less atomic percentage (atomic %), 7.5 atomic % or less, 5 atomic % or less, 4 atomic % or less, 3 atomic % or less, 2 atomic % or less, or about 1.5 atomic %.

[0067] The deposited metal or metal alloy layer plays several important roles. Primarily, it acts as a visual layer (optionally along with other layers in a decorative coating), providing the desired aesthetic, such as that of chrome or stainless steel. Additionally, when deposited on the first surface of a plastic substrate, it acts as a light-absorbing layer, thereby reducing the substrate's exposure to UV light during use. Finally, it comes into direct contact with the plastic substrate, thus forming a stress-controlling layer. This differs from typical PVD-deposited decorative coatings, which utilize an intermediate layer between the substrate and the metal or metal alloy layer to control the stress difference between them.

[0068] The properties of the deposited decorative coating are critical in ensuring suitable adhesion to the plastic substrate. A significant factor is the residual stress of the decorative coating. As shown in the examples, decorative coatings containing chromium and zirconium, exhibiting compressive residual stress, failed the UV resistance test (according to SAE J2527). Therefore, in some preferred embodiments, the decorative coating is deposited under conditions that result in a tensile residual film stress displacement. Preferably, the decorative coating is deposited under conditions that result in a residual film stress displacement of the deposited decorative coating that is less than or equal to -50 μm, less than or equal to -240 μm, or less than or equal to -765 μm.

[0069] "Residual stress" refers to stress that is not caused by a directly applied load or is a result of differences in thermal expansion between the coating and its substrate or between different layers within the coating. Methods for evaluating the residual stress and stress displacement of a deposited decorative coating are known in the art, such as those described in the embodiments included herein.

[0070] Decorative coatings may include layers other than metallic or metal alloy layers. These additional layers can be used to adjust residual stress in the decorative coating, modify its visual properties, or alter other properties, such as improving external adhesion.

[0071] In some embodiments, the decorative coating may comprise a series of stacked layers. For example, publication WO 2015 / 131223 (entirely incorporated herein) discloses a coating comprising multiple layers of absorbing and transmitting layers. Chromium and zirconium alloy layers alternating with silica layers are particularly disclosed. Different visual effects can be produced by varying the thickness and number of layers. Therefore, in some embodiments of the invention, the decorative coating comprises additional layers such as optical modification layers or adhesion control layers. In some embodiments, both functions are provided by the same layer. In other embodiments, these two functions are provided by different layers.

[0072] As used herein, an optical modification layer is a layer that may be included in addition to a metal or metal alloy layer, altering the overall visual appearance of the decorative coating. This layer may be transparent or translucent (or have a degree of transparency / opaqueness). However, in some embodiments, the optical modification layer is transparent.

[0073] As used herein, an adhesion-modifying layer refers to a layer that improves adhesion to a decorative coating. This may include a layer at the interface between a substrate and a metal or metal alloy layer (which is not a protective coating) or a layer on the outermost surface of the decorative coating (which promotes improved adhesion to the decorative coating). In this latter embodiment, it is desirable that the adhesion-promoting layer be transparent.

[0074] Particularly preferred optical modification layers and adhesion promoting layers comprise silicon. Silica is formed when deposited in the presence of oxygen. Therefore, in preferred embodiments, one (or more) optical modification layers and / or one (or more) adhesion promoting layers comprise silicon dioxide. Indeed, silicon dioxide can perform the functions of both an optical modification layer and an adhesion promoting layer. In some embodiments, the decorative coating comprises multiple layers of silicon dioxide and may also comprise multiple layers of metal or metal alloys such as chromium / zirconium.

[0075] Adding additional layers can alter the total residual stress of the decorative coating. Silica, for example, is inherently compressible when deposited, and therefore including silica in the decorative layer shifts the total residual stress toward compression. Because it is important to maintain the total residual stress of the decorative layer in a tensile state, the thickness of any deposited silica layer or the number of deposited silica layers needs to be matched to prevent the total residual stress from becoming compressive.

[0076] Furthermore, the deposition parameters of the metal layer can be adjusted to change the tensile stress once the metal or metal alloy layer is deposited. Of particular importance are the power used during layer deposition and the gas flow during deposition. Figure 2 The study shows that increasing the gas flow (e.g., argon flow) while maintaining the target power during deposition increases the residual tensile stress in the deposited coating (even if it is more tensile, thus making the stress displacement more negative). Furthermore, increasing the target power while maintaining the gas flow also increases the residual tensile stress in the deposited coating.

[0077] Deposition parameters can also alter the optics of the final deposited coating, and this can be determined by technicians and adjusted for their desired applications and aesthetics.

[0078] After applying a decorative coating to a plastic substrate, a protective coating is applied. This protective coating may be applied to only one surface of the plastic article (e.g., by spraying) or to both surfaces of the plastic article (e.g., by dip coating). Preferably, the protective coating is applied to the first surface of the plastic article. Thus, in an embodiment where the decorative coating is the first surface coating, the protective coating is applied to the decorative coating.

[0079] In some embodiments, the coating protects against aging and specifically absorbs or reflects UV light. In some embodiments, the protective coating is a hard coating. In this respect, a coating that is claimed to be a "hard coating" is a coating that is harder and more rigid than the substrate, thereby improving the substrate's abrasion resistance. Such an abrasion-resistant hard coating is a coating that reduces damage due to impact and scratching. Abrasion resistance can be measured by tests such as ASTM F735 "Standard Test Method for Abrasion Resistance of Transparent Plastics and Coatings Using the Oscillating Sand Method", ASTM D4060 "Standard Test Method for Abrasion Resistance of Organic Coatings", by Taber Abrader, or by using the well-known Steel Wool Test.

[0080] Furthermore, some plastic substrates can be damaged by certain solvents; for example, polycarbonate is damaged by acetone. A requirement for many products suitable for the decorative coatings of this invention is that they are "chemically resistant," meaning they can withstand exposure to common solvents such as diesel, petroleum, battery acids, brake fluid, antifreeze, acetone, ethanol, automatic transmission fluid, hydraulic fluid, and ammonia-based window cleaners. In this regard, it will be understood that hard coatings ideally provide products carrying the decorative coatings of this invention with such chemical resistance.

[0081] The hard coating is preferably formed of one or more abrasion-resistant layers and may include a primer layer of a preferred material that bonds well to the decorative layer and forms for subsequent abrasion-resistant layers. The primer layer may be provided by any suitable material and may be, for example, an organic resin such as an acrylic polymer, a copolymer of acrylic monomers and methacryloxysilane, or a copolymer of methacrylic monomers and acrylic monomers having benzotriazole or benzophenone groups. These organic resins may be used alone or in combination of two or more.

[0082] The wear-resistant layer is preferably formed from one or more materials selected from the following: organosilicon, acrylics, urethanes, melamine, or amorphous SiO2. x C y H zMost preferably, the wear-resistant layer is an organosilicone layer due to its excellent wear resistance and compatibility with physical vapor deposition films. For example, the wear-resistant layer comprising an organosilicone polymer can be formed by methods such as dip coating to form a compound layer selected from the following compounds and then curing the layer: trialkoxysilanes or triacyloxysilanes, such as methyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxyethoxysilane, methyltriacetoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxyethoxysilane, vinyltrimethoxyethoxysilane, etc. Phenylacetoxysilane, phenyltrimethoxysilane, phenyltriacetoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, γ-chloropropyltripropoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-(β-glycidoxyethoxy)propyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane Methoxysilanes, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, β-cyanoethyltriethoxysilane, etc.; and dialkoxysilanes or diacyloxysilanes such as dimethyldimethoxysilane, phenylmethyldimethoxysilane, dimethyldiethoxysilane, phenylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, etc. Oleoxypropylphenyl dimethoxysilane, γ-glycidoxypropylphenyl diethoxysilane, γ-chloropropylmethyl dimethoxysilane, γ-chloropropylmethyl diethoxysilane, dimethyldiacetoxysilane, γ-methacryloyloxypropylmethyl dimethoxysilane, γ-methacryloyloxypropylmethyl diethoxysilane, γ-mercaptopropylmethyl dimethoxysilane, γ-mercaptopropylmethyl diethoxysilane, γ-aminopropylmethyl dimethoxysilane, γ-aminopropylmethyl diethoxysilane, methylvinyldimethoxysilane, methylvinyldiethoxysilane, etc.

[0083] Commercially available hard coatings include Momentive hard coatings such as UVHC3000, UVHC5000, PHC587B / C, PHCXH100P, and AS4700F. Each of these coatings has different abrasion resistance, weather resistance, and deposition parameters. Therefore, those skilled in the art will be able to select the appropriate coating for the intended purpose of the plastic article. In some preferred embodiments, the hard coating is Momentive PHC587B or AS4700F. In the most preferred embodiment, the hard coating is Momentive PHC587B.

[0084] The abrasion-resistant layer can be applied to plastic articles by dip coating in a liquid followed by solvent evaporation, or by plasma-enhanced chemical vapor deposition (PECVD) via a suitable monomer. Alternative deposition techniques such as flow coating and spraying are also suitable. To improve the abrasion resistance of the hard coating, a subsequent coating can be added, preferably within 48 hours, to avoid premature contamination and aging of the coating.

[0085] Applying a protective coating can affect the stress of the decorative coating. Therefore, in some embodiments, the residual stress of the decorative coating is the residual stress prior to any further treatment of the decorative coating, and particularly prior to the application of the protective coating. Furthermore, those skilled in the art will understand that the application of the protective coating can be altered, thereby affecting any additional stress applied to the coated plastic article as a result of the protective coating. As is known in the art, the protective coating itself can have residual stress when cured, and this can be altered during the application of the protective coating. Some examples of parameters that can be adjusted during the application of the protective coating include the method of application (e.g., dip coating or spray coating), whether the coating is applied to one or both sides, the thickness of the applied coating, the use of a primer prior to the application of the coating, the curing temperature of the protective coating, and the cooling rate of the coating (depending on the properties of the applied coating). Each of these factors can be altered based on what is known in the art, and the results can be evaluated based on known methods for evaluating residual stress, including the methods illustrated herein.

[0086] When applied over a decorative coating, a protective coating can alter the appearance of the coating. In some embodiments, the protective coating comprises a matting additive applied to the coated plastic article. In this regard, a matting effect is known to be achieved due to the diffusion effect produced by the small (typically ~5 μm) particles of the matting additive. A "satin" appearance can also be achieved by altering the protective coating by adding a matting additive. This is characterized by a significant diffuse reflection component (e.g., diffuse reflection between ~10% and 30%).

[0087] Plastic articles prepared by the methods of this invention may include additional visual features to improve their aesthetics or functionality. In some embodiments, the plastic substrate includes a visible texture. Thus, when a decorative coating is applied, the visible texture appears in the coating. Applying a protective coating to a plastic substrate typically smooths the surface of the plastic substrate and often hides the texture in the substrate. In some cases, this is desirable. However, subtle visual textures are often desired, and such subtle visual textures cannot be achieved when a protective coating is applied to the substrate before depositing the protective coating. However, this invention alleviates this. Therefore, in some embodiments, the plastic substrate has or is provided with a visual texture. In some embodiments, the plastic substrate has or is provided with two visually distinct textures.

[0088] As used herein, "visible texture" refers to a texture that is visible to the naked eye after the deposition of a decorative coating and can be distinguished from a coated plastic substrate with a smooth surface. In some embodiments, the visible texture has a median average toughness (Ra) curve of at least 0.5 μm. In some embodiments, the visible texture has a median average Ra of at least 0.7 μm. In some embodiments, the visible texture has a median average Ra of at least 0.9 μm. In some embodiments, the visible texture has a median average Ra of at least 1 μm. In some embodiments, the visible texture has a median average Ra of at least 1.2 μm. In some embodiments, the visible texture has a median average Ra of at most 2 μm. In some embodiments, the visible texture has a median average Ra of at most 1.8 μm. In some embodiments, the visible texture has a median average Ra of at most 1.6 μm. In some embodiments, the visible texture has a median average Ra of at most 1.5 μm. In some embodiments, the visible texture has a median average Ra of at most 1.4 μm. In some embodiments, the visible texture has a median mean roughness profile (Ra) of 0.5 to 2 μm. In some embodiments, the visible texture has a median mean roughness profile of 0.7 to 1.8 μm. In some embodiments, the visible texture has a median mean roughness profile of 1 to 1.5 μm. In some embodiments, the visible texture has a median mean roughness profile of approximately 1.2 μm.

[0089] As noted above, the present invention aims to allow the preparation of plastic articles with a decorative coating having sufficient elasticity for use in automotive applications. Therefore, in some embodiments, plastic articles (which can be formed by the method of the present invention) that pass one or more of the following tests are provided:

[0090] Cross-hatching adhesion: ISO 2409, using a single-blade cutting tool and 3M Scotch 8981 tape. Adhesion level ≤1.

[0091] Abrasion - Steel Wool: A 30cm long skeleton of grade 0 steel wool was folded into a 40mm x 40mm square pad and fitted into a Sutherland Ink Rub tester. A force of 1.9kg was applied to the sample surface for 75 cycles.

[0092] Abrasion-scratch test: A 30cm long skeleton of grade 0000 steel wool was folded into a 40mm x 40mm square pad and fitted into a Sutherland Ink Rub tester. A force of 0.9kg was applied to the sample surface for 10 cycles.

[0093] Chemical resistance: A 300×300mm cotton cloth is soaked in 50mL of each reagent. The soaked reagent is applied to the coated surface and stored at laboratory ambient temperature for 48 hours, after which the reagent is removed and the coated surface is wiped with a coarse cotton cloth for 10 cycles. In some embodiments, the reagent is selected from one or more of the following: brake fluid, coolant, engine oil, isopropanol, automatic transmission fluid, Armor All. TM Hydraulic oil, Coca-Cola TM Window cleaner, Spray'n'wipe TM Acid sweat, alkaline sweat, tar remover, chrome polish, chrome cleaner, Mortein TM Paint solvent oil, engine cleaner, car wash detergent, 33% US detergent, 100% EU detergent.

[0094] Water immersion: Immerse the sample in water at 40°C for 320 hours.

[0095] Short-term heat: Expose the sample to 110°C for 7 hours.

[0096] Thermal cycling: The sample was exposed to the following 10 cycles: 75°C ± 2°C for 4 hours, transitioned to 38°C ± 2°C and 95% ± 5% relative humidity for 16 hours, followed by -30°C ± 2°C for 4 hours.

[0097] Thermal shock: Expose the sample to 200 cycles of -40°C to 85°C, 1 hour / cycle.

[0098] Salt spray: Expose the sample to salt spray for 480 hours in accordance with ASTM B 117.

[0099] High-temperature aging: The sample was exposed to 80°C for 500 hours.

[0100] Low temperature aging: The sample was exposed to -40°C for 240 hours.

[0101] Humidity aging: Expose the sample to 40°C / 95%RH for 500 hours.

[0102] UV resistance: Xenon arc exposure at 1250 kJ / m², according to SAE J2527. Adhesion level ≤1.

[0103] Turn to the remaining attached figures, in Figure 3 The present invention describes a coated plastic article 1 prepared by the method of the present invention. The coated plastic article 1 comprises a plastic substrate 2 having first and second surfaces. The first surface is provided with a metal alloy layer 3 comprising chromium and zirconium, which is directly deposited on the substrate 2 via physical vapor deposition. A protective coating 4 of Momentive PHC587B is provided to at least the outermost surface (which, in this illustrated embodiment, is the first surface of the article).

[0104] exist Figure 4 This section describes another embodiment of a coated plastic article 1 prepared by the method of the present invention. The article has a decorative coating comprising a metal alloy layer 3 of chromium and zirconium and an additional layer 5 of silicon dioxide. These two layered decorative coatings are then coated with a protective coating 4.

[0105] Figure 5 Further embodiments of the coated plastic article 1 prepared by the method of the present invention are provided. This embodiment includes a decorative layer comprising multiple stacks of chromium and zirconium alloy layers 3 and 6 alternating with silicon dioxide layers 5 and 7. These four decorative coatings are then coated with a protective coating 4.

[0106] exist Figure 6 Further embodiments of the coated plastic article 1 prepared by the method of the present invention are provided. This plastic article is related to... Figure 3 The same as that provided in the previous section, however, the second side of the plastic article 1 is provided with a mask 8 to reduce light transmittance. In the area where the mask 8 is not provided, the plastic article 1 is visible through the translucent metal alloy layer 3 from the backlight 9 on the second side. This allows for the provision of backlighting symbols that are substantially invisible in the absence of backlighting. Example

[0107] The following examples provide specific embodiments of the invention disclosed herein and are not intended to limit the claimed invention.

[0108] Brushed metallic finish on stainless steel

[0109] The following methods are used to prepare various plastic products with a brushed stainless steel appearance and a glossy protective coating.

[0110] Substrate preparation

[0111] The polycarbonate substrate is injection molded using a patterned injection molding tool and stored in a manner that avoids substrate contamination until the coating is applied.

[0112] Before coating, the substrate is thoroughly purged with ionized compressed air to remove any particles that have settled on the surface and to eliminate static electricity. The substrate is then loaded into the PVD coating barrel and purged a second time immediately before entering the vacuum coating chamber.

[0113] Deposition of decorative coatings

[0114] Three separate coating schemes were performed to allow for the evaluation of the utility and elasticity of the coated plastic articles. The three schemes are as follows:

[0115] Sample 1: Plasma pretreated polycarbonate substrate: silicon dioxide (SiO2) layer: chromium / zirconium layer (CrZr): silicon dioxide (SiO2) layer.

[0116] Sample 2: Plasma-free pretreated polycarbonate substrate: silica layer (SiO2): chromium / zirconium (CrZr) layer: silica layer (SiO2).

[0117] Sample 3: Plasma-free pretreated polycarbonate substrate: chromium / zirconium layer (CrZr): silicon dioxide layer (SiO2).

[0118] The parameters of PVD deposition and the properties of the deposited coating are described in Table 1 below.

[0119] Table 1 - PVD Coating Parameters and Properties

[0120]

[0121] ^Pretreatment = glow discharge electrode (stainless steel); CrZr target = chromium / zirconium (98.5 / 1.5 atomic%); SiO2 target = dual rotatable silicon target (99.90% purity).

[0122] Protective coating

[0123] A coating of Momentive PHC587B is applied to the plastic article. This outer protective coating covers and protects the decorative coating by improving its UV resistance and abrasion resistance. Therefore, the protective coating acts as a hard coating and also as a UV-resistant coating.

[0124] The outer coating was applied using an automated dip-coating apparatus as described below and according to the parameters set forth in Table 2. The coated substrate was left to stand for 10 minutes to allow the solvent to evaporate until the surface was substantially non-sticky. Subsequently, the coated substrate was cured in a curing oven at 130°C for 71 minutes to provide a protective, hard-coated surface.

[0125] Specifically, the following parameters are used to apply the protective coating:

[0126] Table 2 - Protective Coating Deposition Parameters

[0127] Material Momentive PHC-587B Deposition methods Dip coating and cure at 130°C Thickness (μm) 7-9um

[0128] Satin metallic finish

[0129] The following methods are used to prepare various plastic products with a satin metallic appearance.

[0130] Substrate preparation

[0131] The polycarbonate substrate is injection molded into the desired shape and stored in a manner that avoids substrate contamination until the coating is applied.

[0132] Before coating, the substrate is thoroughly purged with ionized compressed air to remove any particles that have settled on the surface and to eliminate static electricity. The substrate is then loaded into the PVD coating cylinder and immediately purged with a second layer before entering the vacuum coating chamber.

[0133] Deposition of decorative coatings

[0134] Four separate coating schemes were implemented to allow for the evaluation of the effectiveness and elasticity of the coated plastic substrates. The four schemes are as follows:

[0135] Samples 4 to 6: Plasma-free pretreated polycarbonate substrate: chromium / zirconium layer (CrZr): silicon dioxide (SiO2) layer.

[0136] Sample 7: Plasma-free pretreated polycarbonate substrate: Chromium / Zirconium (CrZr) layer: Silica layer (SiO2): Chromium / Zirconium (CrZr) layer: Silica layer (SiO2).

[0137] The parameters of PVD deposition and the properties of the deposited coating are described in Table 3 below.

[0138] Table 3 - PVD Coating Parameters and Properties

[0139]

[0140]

[0141] ^Pretreatment = glow discharge electrode (stainless steel); CrZr target = chromium / zirconium (98.5 / 1.5 atomic%); SiO2 target = dual rotatable silicon target (99.90% purity).

[0142] Protective Surface Coating - Satin Finish

[0143] To provide a satin metallic finish and a protective decorative coating, Momentive PHC587B is applied to the outer surface of the decorative coating. This protective coating differs from the coatings used in Examples 1 to 3 in two ways. First, Momentive PHC587B includes additives that cause visible light diffusion, thereby producing a satin finish. Second, instead of dip coating, the protective coating is applied by automated spraying in a dedicated thin-film spray bath. This results in the coating being applied only to the first side of the plastic substrate, not the second uncoated side (i.e., the coating is applied only to the decorative coating side).

[0144] The coated substrate was left to stand for 10 minutes to allow the solvent to evaporate until the surface was essentially non-sticky. Subsequently, the coated substrate was cured in a curing oven at 130°C for 71 minutes to provide a protective hard-coated surface.

[0145] Specifically, the following parameters (as illustrated in Table 4) are used to provide a satin-finish decorative coating:

[0146] Table 4 - Satin Hard Coating Deposition Parameters

[0147] Material Momentive PHC-587B + Tospearl 2000B (at 3.5% wt / wt) Deposition methods Spray and cure at 130°C Thickness (μm) 8-16um

[0148] result

[0149] Measuring tensile stress

[0150] Film stress was measured by depositing a PVD film on a thin glass (150 μm) microscope coverslip and evaluating the residual stress of the coating using a Sigma Physik SIG-500SP apparatus. This apparatus provides measurements of stress displacement (μm) and stress (MPa).

[0151] The device uses two parallel laser beams nominally spaced 20 mm apart. Sensors are placed to detect the distance between the two beams reflected from the glass slide, thereby allowing the determination of the slide's curvature. Measurements are taken before and after the physical vapor deposition of the decorative coating onto the slide, and comparison of the two measurements allows for the calculation of stress displacement (μm). Essentially, a film with a compressive residual stress distribution will result in a convex curvature of the coated glass slide (i.e., the edges of the slide will bend away from the film-coated side), while a film with tensile residual stress will have a concave profile (the edges of the slide will bend away from the film-coated side). This displacement can be converted into MPa by taking into account the thickness of the glass slide and the film.

[0152] Figure 7 A schematic diagram showing the measurement results of the stress displacement of the decorative coating of the disclosed sample. Figure 7A describes an incident light beam 10, which is split into two beams and guided to a glass substrate 11 via a semi-transparent mirror 12. A portion of the beam is reflected from the glass substrate 11 onto the sensor 13. The distance (X) between the two beams on the untreated substrate is measured. b =X 之前 ). Figure 7 B illustrates the deformation of the glass slide 11 caused by the deposition of a coating 14 with residual tensile stress. As can be seen, the glass slide forms a concave curvature, with the edges of the slide bending towards the decorative coating 14. This curvature causes the light beam reflected from the coated substrate to converge at the sensor 13, which is measured as the second distance (X). a1 (X) a =X 之后 ).

[0153] Figure 7 C illustrates the deformation of the glass slide 11 caused by the deposition of a coating 14 with compressive residual stress. In contrast to a coating with tensile residual stress, the slide forms a convex curvature in which the edges of the slide bend away from the coating 14. This causes the light beam reflected from the coated substrate to diverge at the sensor 13, which is measured as a second distance (X). a2 ).

[0154] Then, the stress displacement of the deposited film is calculated using the following formula: Stress displacement (μm) = X a -X b

[0155] As is obvious, a coating with tensile residual stress will provide a negative stress displacement (i.e., X) in μm. a1 <X b Coatings with compressive residual stress will provide positive measurement results (i.e., X). a2 >X b ).

[0156] In this context, the strain amplitude at the substrate-film interface is important in promoting adhesion between the substrate and the film. This strain amplitude is best measured and compared by recording the amount of deformation (stress displacement (μm)) of the glass slide. Stress displacement measurements include the coating thickness relative to the stress reported in MPa. Therefore, a thick coating with low residual stress (as measured in MPa) will exert the same stress displacement on the substrate as a thinner coating with relatively high residual stress (as measured in MPa). As a result, measurements of residual stress in MPa are appropriate when the coating thickness is the same but do not allow for direct comparison when the coating thickness varies. Therefore, film stress is reported herein as stress displacement (μm) and all measurements are performed before the addition of a protective coating.

[0157] In addition, the reflectance and transmittance of the coated plastic products were evaluated using a HunterLab Ultrascan Pro spectrophotometer.

[0158] The results of the evaluation of residual stress and visual assessment are provided in Table 5 below.

[0159] Table 5 - Residual stress, light reflectance, and light transmittance of coated plastic samples

[0160]

[0161] # The reflected and transmitted L values ​​were evaluated using a HunterLab Ultrascan Pro spectrophotometer via (CIEL*a*b*). * .

[0162] To evaluate whether the samples prepared as described above would be robust enough for use in automotive applications, a series of durability tests were conducted.

[0163] The tests and results are summarized in Table 6 below.

[0164] Table 6 - Durability Tests of Coated Samples

[0165]

[0166]

[0167] The following provides a description of each of the tests conducted in Table 6:

[0168] Cross-hatching adhesion: Use a single-blade cutting tool and 3M Scotch 8981 tape for ISO 2409. Adhesion level ≤ 1.

[0169] Abrasion - Steel Wool: A 30cm long skeleton of grade 0 steel wool was folded into a 40mm x 40mm square pad and fitted into a Sutherland Ink Rub tester. A force of 1.9kg was applied to the sample surface for 75 cycles.

[0170] Abrasion-scratch test: A 30cm long skeleton of grade 0000 steel wool was folded into a 40mm x 40mm square pad and fitted into a Sutherland Ink Rub tester. A force of 0.9kg was applied to the sample surface for 10 cycles.

[0171] Chemical resistance: A 300×300mm cotton cloth is soaked in 50mL of each reagent. The soaked cloth is then applied to the coated surface and stored at laboratory ambient temperature for 48 hours (unless otherwise specified). After this, the reagent should be removed from the coated surface, and the surface should be wiped with a coarse cotton cloth for 10 cycles. Reagents used include: brake fluid, coolant, engine oil, isopropanol, automatic transmission fluid, and Armor All. TM Hydraulic oil, Coca-Cola TM Window cleaner, Spray'n'wipe TM Acidic sweat, alkaline sweat, tar remover, chrome polish, chrome cleaner, Mortein TM Paint solvent oil, engine cleaner, car wash detergent, 33% US detergent, 100% EU detergent.

[0172] Water immersion: Immerse the sample in water for 320 hours and maintain at 40°C.

[0173] Short-term heat: Expose the sample to 110°C for 7 hours.

[0174] Thermal cycling: The sample was exposed to the following 10 cycles: 75°±2°C for 4 hours, followed by 38°±2°C and 95%±5% relative humidity for 16 hours, followed by -30°±2°C for 4 hours.

[0175] Thermal shock: Expose the sample to 200 cycles of -40°C to 85°C, 1 hour / cycle.

[0176] Salt spray: Expose the sample to salt spray for 480 hours in accordance with ASTM B 117.

[0177] High-temperature aging: The sample was exposed to 80°C for 500 hours.

[0178] Low temperature aging: The sample was exposed to -40°C for 240 hours.

[0179] Humidity aging: The sample was exposed to 40°C and 95% relative humidity for 500 hours.

[0180] UV resistance: Provide the sample with 1250 kJ / m² xenon arc exposure according to SAE J2527. Adhesion level ≤ 1.

[0181] As can be seen from Table 5, all samples passed every durability test except for UV resistance (according to SAE J2527). When exposed to UV radiation, four of the seven samples passed and three failed. Notably, all three failed samples had decorative coatings with residual stress displacement in compression. Therefore, it can be concluded that, based on these results, the residual film stress displacement of decorative coatings needs to be tensile for plastic articles suitable for automotive applications, such as automotive interiors.

[0182] It should be understood that various modifications, additions and / or substitutions may be made to the foregoing description without departing from the scope of the invention as defined in the appended provisional claims.

[0183] This invention can also be broadly defined as comprising any or all combinations of parts, elements, and features individually or collectively pointed out or indicated in the specification of this application. In the foregoing description, when references are made to an integer or component having its known equivalents, these integers are combined as if described separately.

[0184] When any or all of the terms “comprising,” “including,” “contains,” or “comprises” are used in this specification (including the provisional claims), they shall be construed as specifying the presence of the said feature, unit, step, or component, but without excluding the presence of one or more other features, units, steps, or components, or groups thereof.

[0185] Future patent applications may be filed in any competent jurisdiction based on this application or by claiming priority to this application. It should be understood that the following provisional claims are provided by way of example only and are not intended to limit the scope of protection that may be claimed in any such future application. At a later date, features may be added to or omitted from the provisional claims to further define or redefine one or more inventions.

Claims

1. A method for preparing a coated plastic article, the method comprising: a. Provide a plastic substrate having at least first and second surfaces; b. A decorative coating containing a metallic layer is deposited on the first surface of the plastic substrate using physical vapor deposition; and c. Apply a protective coating to at least a first surface of the plastic article. There was no plasma pretreatment of the plastic substrate prior to the deposition of the decorative coating. The decorative coating metal layer is deposited directly on the plastic substrate, the decorative coating is deposited under conditions that cause tensile residual film stress in the decorative coating, and the residual film stress displacement of the decorative coating is less than or equal to -50 µm.

2. The method of claim 1, wherein the decorative coating is deposited under conditions that result in a residual film stress displacement of the decorative coating being less than or equal to -240 µm.

3. The method of claim 1, wherein the decorative coating is deposited under conditions that result in a residual film stress displacement of the decorative coating being less than or equal to -765 µm.

4. The method of claim 1, wherein the protective coating is a hard coating.

5. The method of claim 1, wherein the protective coating is an ultraviolet blocking coating.

6. The method of claim 1, wherein the protective coating is applied to the decorative coating.

7. The method of claim 1, wherein the protective coating is applied to the opposing surfaces of the decorative coating and the plastic substrate.

8. The method of claim 1, wherein the decorative coating comprises an adhesion-promoting layer.

9. The method of claim 1, wherein the decorative coating comprises an optically modified layer.

10. The method of claim 8, wherein the adhesion-promoting layer is transparent.

11. The method of claim 9, wherein the optically modified layer is transparent.

12. The method of claim 8, wherein the adhesion-promoting layer comprises silicon.

13. The method of claim 9, wherein the optically modified layer comprises silicon.

14. The method of claim 12, wherein the adhesion-promoting layer is deposited in the presence of oxygen.

15. The method of claim 13, wherein the optically modified layer is deposited in the presence of oxygen.

16. The method of claim 8, wherein the deposited adhesion-promoting layer is silicon dioxide.

17. The method of claim 9, wherein the deposited optical modification layer is silicon dioxide.

18. The method of claim 1, wherein the metal layer comprises chromium (Cr), aluminum (Al), titanium (Ti), nickel (Ni), molybdenum (Mo), zirconium (Zr), tungsten (W), silicon (Si), niobium (Nb), tantalum (Ta), vanadium (V), cobalt (Co), manganese (Mn), silver (Ag), zinc (Zn), indium (In), germanium (Ge), tin (Sn), and mixtures thereof; and oxides, nitrides, borides, fluorides, or carbides thereof, and mixtures thereof.

19. The method of claim 1, wherein the metal layer comprises chromium (Cr).

20. The method of claim 1, wherein the metal layer comprises zirconium (Zr), aluminum (Al), titanium (Ti), germanium (Ge), indium (In), copper (Cu), cobalt (Co), or molybdenum (Mo).

21. The method of claim 1, wherein the metal is a mixture of chromium and zirconium.

22. The method of claim 1, wherein the plastic substrate provided prior to the deposition of the decorative coating comprises a visible texture.

23. The method of claim 1, further comprising providing a visible texture to the plastic substrate.

24. The method of claim 1, further comprising providing the plastic substrate with two visually distinct textures.

25. The method of claim 1, wherein the plastic substrate has been injection molded or formed from a plastic capable of being injection molded.

26. The method of claim 1, wherein the plastic substrate is polycarbonate.

27. A coated plastic article prepared by any one of claims 1 to 26.

28. The coated plastic article of claim 27, wherein the coated plastic article passes the SAE J2527 accelerated UV test.

29. The coated plastic article according to claim 27 or 28, comprising: a plastic substrate having first and second surfaces, a decorative coating comprising a metal layer deposited directly on the plastic substrate, and a protective coating applied to the first surface of the plastic article, wherein the residual film stress displacement of the decorative coating is tensile and less than or equal to -50 µm, and the coated plastic article passes the SAE J2527 accelerated UV test.

30. The coated plastic article of claim 29, wherein the residual stress of the deposited decorative coating is measured by residual stress displacement.

31. The coated plastic article according to claim 29, wherein the residual film stress displacement of the decorative coating is less than or equal to -240 µm.

32. The coated plastic article of claim 29, wherein the residual film stress displacement of the decorative coating is less than or equal to -765 µm.

33. The coated plastic article according to claim 29, wherein the protective coating is a hard coating.

34. The coated plastic article according to claim 29, wherein the protective coating is an ultraviolet blocking coating.

35. The coated plastic article of claim 29, wherein the coated plastic article includes a texture visible on the plastic substrate.

36. The coated plastic article of claim 29, wherein the protective coating is provided only on a first surface of the plastic article.

37. The coated plastic article of claim 29, wherein the protective coating is provided only on the surface of the plastic article having the decorative coating.

38. The coated plastic article of claim 29, wherein the protective coating is provided on both the surface of the plastic article having the decorative coating and the opposite surface of the plastic article.

39. The coated plastic article according to claim 29, wherein the metal layer comprises chromium (Cr), aluminum (Al), titanium (Ti), nickel (Ni), molybdenum (Mo), zirconium (Zr), tungsten (W), silicon (Si), niobium (Nb), tantalum (Ta), vanadium (V), cobalt (Co), manganese (Mn), silver (Ag), zinc (Zn), indium (In), germanium (Ge), tin (Sn), and mixtures thereof; and oxides, nitrides, borides, fluorides, or carbides thereof, and mixtures thereof.

40. The coated plastic article of claim 29, wherein the metal layer comprises chromium (Cr).

41. The coated plastic article according to claim 29, wherein the metal layer comprises zirconium (Zr), aluminum (Al), titanium (Ti), germanium (Ge), indium (In), copper (Cu), cobalt (Co), or molybdenum (Mo).

42. The coated plastic article according to claim 29, wherein the metal is a mixture of chromium and zirconium.

43. The coated plastic article of claim 29, wherein the decorative coating further comprises an adhesion-promoting layer.

44. The coated plastic article of claim 29, wherein the decorative coating further comprises an optically modified layer.

45. The coated plastic article of claim 43, wherein the adhesion-promoting layer is transparent.

46. ​​The coated plastic article according to claim 44, wherein the optical modification layer is transparent.

47. The coated plastic article of claim 43, wherein the adhesion-promoting layer comprises silicon.

48. The coated plastic article of claim 44, wherein the optical modification layer comprises silicon.

49. The coated plastic article according to claim 43, wherein the deposited adhesion-promoting layer is silicon dioxide.

50. The coated plastic article according to claim 44, wherein the deposited optical modification layer is silicon dioxide.

51. The coated plastic article of claim 29, wherein the plastic article includes a mask to provide a portion for controlled light transmission.

52. The coated plastic article of claim 51, wherein the portion through which controlled light passes forms a symbol.

53. The coated plastic article of claim 29, wherein the plastic substrate has been injection molded or formed from a plastic capable of being injection molded.

54. The coated plastic article according to claim 29, wherein the plastic substrate is polycarbonate.

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