Decorated polymer substrate and method for obtaining the same

Abstract

The present invention relates to a polymer substrate having a decorative coating consisting of a boron-doped silicon oxide protective top layer, the boron-doped silicon oxide containing Si, O, B, H and OH groups, and having a boron content of 4 to 12 atomic %. The present invention further includes a method for depositing a boron-doped silicon oxide layer containing Si, O, B, H and OH groups and having a boron content of 4 to 12 atomic % on a polymer substrate by hollow cathode type PECVD.

Description

Technical Field

[0001] The present invention relates to a decorative coated polymer substrate comprising a boron-doped silicon oxide protective top layer. The present invention further relates to a plasma enhanced chemical vapor deposition method for depositing a decorative coating comprising a boron-doped silicon oxide protective top layer on a polymer substrate.

Background Art

[0002] Uncoated polymer substrates, such as acrylonitrile-butadiene-styrene (ABS) and, in some cases, polycarbonate (PC) mixed with ABS, often exhibit a dull appearance and thus often need to be coated to increase the amount of reflected light and improve the aesthetic appearance.

[0003] Also, such polymer substrates are frequently used in applications where they are exposed to mechanical wear, particularly scratches.

[0004] It is known to apply a lacquer layer on a polymer substrate for both mechanical protection and aesthetic purposes. However, it has been found that there is still a need to improve the protection provided by such a lacquer layer, at least with respect to scratch resistance. Furthermore, such a lacquer layer is thick, well over 1 μm thick, and requires large amounts of chemicals in a time-consuming deposition process.

[0005] Some polymer substrates have a metal layer provided to obtain the appearance of metal parts. Such coated polymer substrates are used particularly as a substitute for metal parts having a decorative function in vehicles. These metal layers need to protect against chemical attacks such as mechanical wear and oxidation.

[0006] Accordingly, there is a need in the art for a layer that improves the resistance of polymer substrates to chemical and / or mechanical degradation and improves their aesthetic appearance.

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to make available a polymer substrate that is mechanically durable, has good adhesion, is particularly excellent in wear resistance, and at the same time provides a desirable aesthetic appearance.

Means for Solving the Problems

[0008] Accordingly, the present invention relates to a polymer substrate having a coating including a boron-doped silicon oxide protective top layer, the boron-doped silicon oxide containing Si, O, B, and OH groups, and the boron content being 4 to 12 atomic %.

[0009] In a particular embodiment of the present invention, the boron-doped silicon oxide protective top layer is the only layer of the decorative coating.

[0010] In a particular embodiment of the present invention, the decorative coating consists of one or more layers between the substrate and the boron-doped silicon oxide protective top layer.

[0011] Another object of the present invention is to provide a fast and efficient method for depositing a coating including a boron-doped silicon oxide protective top layer on a polymer substrate, the boron-doped silicon oxide containing Si, O, B, and OH groups, and the boron content being 4 to 12 atomic %.

[0012] In a particular embodiment of the present invention, the process of depositing a protective boron-doped silicon oxide layer containing Si, O, B, and OH groups and having a boron content of 4 to 12 atomic % on a polymer substrate includes the following: a. Providing a polymer substrate, b. Providing a linear hollow cathode type plasma source, the source having a length and including at least a pair of hollow cathode plasma generating electrodes for depositing a protective layer on the substrate, and at least a pair of electrodes connected to an AC, DC, or DC pulse generator power supply. c. Inject a plasma-generating reactive gas containing oxygen into the electrodes of the plasma source at a flow rate of 125 to 750 sccm per linear meter of the length of the plasma source; d. Apply a power of 10 to 50 kW per linear meter of the length of the plasma source to the plasma source, and e. Inject a precursor gas at a flow rate of 500 to 2500 sccm per linear meter of the length of the plasma source, inject the precursor gas into the plasma toward at least between the electrodes of each electrode pair of the plasma source, and expose the substrate to the plasma of the plasma source to deposit a protective layer on the polymer substrate.

Brief Description of the Drawings

[0013] To more fully understand the essence of the present invention, please refer to the following details together with the accompanying drawings.

[0014]

Figs. 1 - 3

[0015]

Fig. 4

[0016]

Fig. 5

Mode for Carrying Out the Invention

[0017] The inventors have surprisingly discovered that the protective top layer of the present invention provides a polymer substrate with improved aesthetics by increasing the glossiness determined by gloss measurement, and further provides good mechanical resistance in a wear test.

[0018] The decorative coating preferably does not include an organic adhesive layer or a polymer-based coat. If present, the metal coating may be in direct contact with the substrate, or otherwise the protective top layer may be in direct contact with the substrate. Figure 1 shows a polymer substrate (10) where the protective top layer (1) is in direct contact with the substrate. Figure 2 shows a polymer substrate (10) where the metal coating (2) is in direct contact with the substrate and the protective top layer (1) is in direct contact with the metal coating (2).

[0019] The polymer substrates of the present invention can be used as decorative elements in a wide range of applications such as electrical products, electronic devices, furniture, or building components. Their enhanced durability is particularly suitable for use in vehicles such as automobiles. This latter application is particularly interesting when the substrate is polymer-based and is used as an alternative to at least metal parts that perform a decorative function.

[0020] The decorative coating on the polymer substrate may further have a metal coating between the substrate surface and the protective top layer.

[0021] This metal coating may be composed of one or more metal layers. The layer of this metal coating may have a thickness of up to 1 μm. Such a metal coating gives the polymer substrate a metallic appearance and enables it to be used as an alternative to metal parts. The protective top layer protects the metal layer from scratches and chemical attacks. Preferably, one or more metal coating layers are deposited by magnetron sputtering.

[0022] Advantageously, the metal coating is in direct contact with the polymer substrate and / or the protective top layer.

[0023] According to one embodiment of the present invention, the metal coating consists of one or more layers made of a material selected from Ag, Cu, Al, Cr, Zr, Ti, Si, NiCr alloy or NiCrW alloy.

[0024] In an advantageous embodiment of the invention, the metal coating consists of two layers. Advantageously, the first adhesion metal layer of NiCr is in direct contact with the polymer substrate and in direct contact with a second metal layer selected from Ag, Cu, Al, Cr, Zr, Ti, Si, and NiCrW alloys. The first layer can enhance the adhesion between the second layer and the substrate.

[0025] The boron-doped silicon oxide protective top layer of the present invention contains OH groups. The presence of OH groups is a characteristic that distinguishes the above coating from magnetron sputtering coatings, which do not provide the same level of protection. As far as the inventors know, it is considered that the boron-doped silicon oxide layer of the present invention has protective ability at least partially depending on the combination of OH groups and boron doping. The presence of OH groups can be determined by Fourier transform infrared spectroscopy (FTIR) for an equivalent protective top layer deposited on a silicon substrate. The presence of OH groups in the protective top layer is determined by the presence of an absorption peak at a wave number of 3000 - 3500 cm -1 corresponding to the -OH stretching vibration. Further absorption peaks corresponding to the Si-OH stretching vibration may be seen at 900 - 1000 cm-1, but these peaks may overlap with stronger peaks of the Si-O stretching vibration.

[0026] In one embodiment of the present invention, the FTIR absorption peak area ratio A OH of the -OH stretching vibration (A SiOSi ) and the Si-O-Si stretching vibration (A OH / A SiOSi is 0.25 - 0.5. The absorption peak of the -OH stretching vibration appears at a wave number of 3300 - 3500 cm -1 , and the absorption peak of the Si-O-Si stretching vibration appears at a wave number of 1080 - 1090 cm -1 .

[0027] In a SiO2-based coating deposited by sputtering, hydrogen may be present in the gas phase unintentionally. However, in a decorative coating, the FTIR absorption peak area ratio A OH / A SiOSiIt is known to be less than 0.05. Furthermore, since aluminum is added to the silicon sputtering target to enhance conductivity, the SiO2-based coating deposited by sputtering generally contains aluminum. The boron-doped silicon oxide layer of the present invention may be free of aluminum.

[0028] The boron-doped silicon oxide layer of the present invention was found to be amorphous and non-rigid when viewed, for example, with a transmission electron microscope.

[0029] The boron-doped silicon oxide layer of the present invention can consist of or consist essentially of silicon, boron, oxygen and hydrogen.

[0030] In any of the above embodiments, the boron-doped silicon oxide layer may have a boron content of 4 to 12 at% of B. Within this doping range, the refractive index remains very low, i.e., 1.4 to 1.5 at a wavelength of 633 nm. Especially when the weight content of SiO2 is at least 80%. At the same time, appropriate chemical resistance of the multilayer coating is obtained and the haze level after thermal strengthening is maintained low, especially maintained at a value of less than 0.3%.

[0031] The boron content in the boron-doped silicon oxide layer is preferably determined by X-ray photoelectron spectroscopy (XPS) or secondary ion mass spectrometry (SIMS) using an appropriate standard for quantitative evaluation.

[0032] According to one embodiment of the present invention, the boron-doped silicon oxide protective top layer may have a thickness of at least 80 nm so as to exhibit more significantly improved durability. This thickness may be employed over a wide range to adjust the optical properties of the finally coated product. Therefore, the thickness of the boron-doped silicon oxide layer may be up to 400 nm, especially up to 350 nm, more especially up to 300 nm. Such a large thickness is not suitable for magnetron sputtering deposition because of the slow deposition rate of the silicon oxide-based coating.

[0033] According to an embodiment of the present invention, the boron-doped silicon oxide layer of the present invention may have an O / Si atomic ratio of 1.9 to 2.6. It has been found that the lower the doping level of boron, the lower the O / Si atomic ratio.

[0034] According to an embodiment of the present invention, the boron-doped silicon oxide coating of the present invention may not particularly contain carbon. Excluding carbon is particularly advantageous for reducing the absorption rate of the layer and helps to reduce the number of defects that occur during the thermal strengthening of the coated product. The presence of carbon, in addition to complicating the integration of the sol-gel coating process in a multi-layer coating process, is a major drawback of the sol-gel coating.

[0035] For the purposes of the present invention, if no carbon signal exceeding the carbon signal noise is detected in either X-ray fluorescence spectroscopy or secondary ion mass spectrometry, the layer is considered to have no carbon. It should be noted that surface contamination that naturally occurs on the coating when exposed to free space, particularly carbon, is ignored in the analysis.

[0036] The boron-doped silicon oxide protective top layer according to the above embodiments, or combinations thereof, can be conveniently deposited using plasma enhanced chemical vapor deposition (PECVD), particularly a linear plasma source such as a hollow cathode plasma source. By operating under vacuum, PECVD can be easily integrated into a vacuum coating line such as a magnetron sputtering line.

[0037] In one embodiment, the present invention relates to a method for depositing a decorative coating including a boron-doped silicon oxide protective top layer on a polymer substrate. The protective top layer includes Si, O, B, and OH groups, has a boron content of 4 to 12 atomic percent, and includes the following: a. Providing a polymer substrate, b. Providing a linear hollow cathode type plasma source, the plasma source including at least a pair of hollow cathode plasma generating electrodes having a length and connected to an AC, DC, or DC pulse generator power supply for depositing the protective top layer on the substrate. c. Inject a plasma-generating reactive gas containing oxygen into the electrodes of the plasma source at a flow rate of 125 to 750 sccm per linear meter of the length of the plasma source; d. Apply power to the plasma source at a power of 10 to 50 kW per linear meter of the length of the plasma source to generate plasma, and e. Inject a precursor gas containing boron, silicon, and hydrogen at a flow rate of 500 to 2500 sccm per linear meter of the length of the plasma source, inject the precursor gas into the plasma at least between the electrodes of each electrode pair of the plasma source, and expose the substrate to the plasma of the plasma source to deposit a protective top layer on the polymer substrate.

[0038] Standard cubic centimeters per minute, i.e., "sccm", is a unit of flow rate measurement indicating cubic centimeters per minute (cm 3 / min) under standard conditions of temperature and pressure of a given fluid. In the present invention, these standard conditions are fixed at a temperature of 0 °C (273.15 K) and a pressure of 1.01 bar.

[0039] According to an embodiment of the present invention, the multi-layer coating further has one or more layers deposited by, for example, magnetron sputtering and / or PECVD. Optionally, another coating may be deposited by the same technique, for example, after the deposition of the protective top layer. Thereby, the above multi-layer coating including a boron-doped silicon oxide protective layer may be formed.

[0040] Stage b) of the process of the present invention requires a low-pressure PECVD plasma source, the pressure of which is preferably 0.13 to 66.66 Pa (0.001 to 0.5 Torr), more preferably 0.13 to 4.00 Pa, still more preferably 0.40 to 2.67 Pa. This apparatus comprises a hollow cathode type linear plasma source including at least a pair of electrodes connected to an AC or DC pulse generator, the frequency of which is usually 5 to 150 kHz, preferably 5 to 100 kHz. Alternatively, this apparatus is connected to a DC generator. The pressure is maintained by a vacuum pump.

[0041] An example of a PECVD apparatus will be described below. The PECVD source is connected to a vacuum chamber or provided within the vacuum chamber. This vacuum chamber is arranged such that it can have several PECVD apparatuses provided adjacent to each other, or can have another deposition source having a different deposition form within the same vacuum chamber or in connected separate vacuum chambers. In some applications, these other deposition sources enabling different deposition forms are flat or rotating cathodes for magnetron sputtering deposition. The deposition sources are selected and combined within a coater to provide a deposition process for a multilayer coating including the protective top layer of the present invention on a glass substrate having a size of at least 3.2×6 m 2 .

[0042] This vacuum chamber may be part of a horizontal coater or a vertical coater and may further have a transfer chamber.

[0043] The linear plasma source is particularly effective for depositing a uniform layer on a large substrate in a dynamic or continuous coating process. The linear plasma source is arranged perpendicular to the running direction of the substrate so as to extend in the length direction across the width of the substrate. The advantage of the linear plasma source is its scalability. Thus, its length can be adapted to substrates of different widths, and the applied power, gas flow rate and precursor flow rate are adapted to be proportional to the length. The width of the linear plasma source extends parallel to the moving direction of the substrate. A showerhead-type plasma source or a point plasma source is not particularly suitable for substrates larger than 1×1 m 2 because coating such large substrates requires a complex arrangement such as an array of multiple sources, etc., and it is difficult to make them uniform.

[0044] The "hollow cathode type plasma source" is to be interpreted as meaning a plasma or ion source that includes one or more electrodes configured to generate hollow cathode discharge. An example of a hollow cathode plasma source is described in US8652586, the entire of which is incorporated herein by reference. Figure 4 shows a hollow cathode type plasma source that can be used in the present invention. This plasma source has at least a pair of hollow cathode electrodes (41, 42) arranged in parallel and connected via an AC power supply (not shown). An electrical insulating material (43) is arranged around the hollow cathode electrodes. The plasma generating gas is supplied through inlets (44) and (45). The precursor gas is supplied through the precursor gas inlet (46) and is led to the plasma curtain (49) through the manifold (47) and the precursor injection slots (48) in the dark space between the electrodes. The AC power supply supplies a changing or alternating bipolar voltage to the two electrodes. The AC power supply first drives the first electrode to a negative voltage to enable plasma formation, and the second electrode is driven to a positive voltage to serve as an anode for the voltage application circuit. Thereafter, as a result, the first electrode is driven to a positive voltage and the roles of the cathode and anode are reversed. When one electrode is driven negatively, a discharge (41a, 42a) is formed in the corresponding cavity. And the other electrode forms an anode, and electrons escape from the plasma through the outlets (41b, 42b) and move to the anode side, thereby completing the electrical circuit. As shown in Figure 5, a curtain-shaped linear plasma (49) is formed in the region between the first and second electrodes above the substrate. This method of driving the hollow cathode with an AC power supply contributes to the formation of a uniform linear plasma having the length of the substrate (10), the length (L12) of the plasma source is perpendicular to the moving direction (T) of the substrate, and the width (W12) of the plasma source is parallel to the moving direction (T) of the substrate.

[0045] In a linear hollow cathode type plasma source, a uniform plasma can be generated without relying on a closed-loop electron drift. It is desired to interpret that "closed-loop electron drift" means an electron flow generated by crossed electric and magnetic fields. In many conventional plasma forming devices, the closed-loop electron drift forms a closed circulation path or a "race track" of the electron flow.

[0046] "AC power" is desired to be interpreted as power from an AC source where the voltage changes at the frequency of a sine wave, rectangular wave, pulse wave, or other waveform. The change in voltage often occurs from negative to positive, i.e., with respect to ground. In the bipolar type, the power output supplied by two leads is generally out of phase by about 180°.

[0047] An "electrode" supplies free electrons during the generation of plasma, for example, while the electrode is connected to a power source that supplies voltage. The electron emission surface of the hollow cathode is considered to be one electrode as a combination. The electrode can be made of materials well known to those skilled in the art, such as steel, stainless steel, copper, or aluminum. However, since different gases may require different electrode materials to maintain the plasma during ignition and operation, these materials must be carefully selected for each plasma enhancement process. It is also possible to improve the performance and / or durability of the electrode by coating it.

[0048] In any plasma source of the present invention, the power density of the plasma is defined as the power wasted in the plasma generated by the electrode, based on the size of the plasma. In a linear hollow cathode type plasma source, the "power density of the plasma" can be defined as the total power applied to the source divided by the overall length of the plasma source.

[0049] The "linear meter of plasma length" refers to the length of the plasma defined as the distance between the ends of the plasma generated by a pair of electrodes in a direction transverse to the moving direction of the substrate to be coated. When the plasma source has a number of electrodes more than a pair, the plasma length is defined as the sum of the distances between the ends of the plasma generated by each pair of electrodes in a direction transverse to the running direction of the substrate to be coated. As is well understood by those skilled in the art, linear hollow cathode plasma sources can be expanded and contracted so that their lengths correspond to the width of the substrates being handled. The length of the plasma source may be, for example, several meters. Therefore, it is reasonable to express the flow rate and the applied power in units that depend on the overall length of the plasma source. For example, if the length of the plasma source is doubled, the applied power and the flow rate will clearly double.

[0050] The following terms used in this specification have the following meanings. The words "a", "an", and "the" mean both singular and plural unless the contrary is clearly stated. By way of example, "a chamber" means one chamber or a plurality of chambers.

[0051] As used in this specification, "Comprise," "comprising," "comprises," and "comprised of" have the same meaning as "include," "including," "includes," or "contain," "containing," "contains," and are inclusive or open-ended terms that identify the presence of what follows the components, and do not exclude or preclude the presence of other, unrecited components, features, elements, members, or steps known in or disclosed in this field.

[0052] The recitation of numerical ranges by endpoints includes the recited endpoints and all numbers and fractions subsumed within that range.

[0053] A pair of electrodes that form a cavity where plasma discharge occurs are connected to a pipe for introducing a reactive plasma generating gas and have an opening through which an ionized gas, i.e., plasma, is discharged.

[0054] The frequency of the power supply connected to the electrodes is 5 to 150 kHz, preferably 5 to 100 kHz.

[0055] At least a pair of electrodes of the linear plasma source may have a length of 250 mm to 4000 mm and a width of 100 mm to 800 mm.

[0056] Such values have the advantage of ensuring a significantly larger amount of reactive gas than the amount of the precursor, whereby the incorporation of carbon in the layer can be controlled and / or avoided. The applied power, the flow rates of the reactive gas and the precursor are adjusted in proportion to the length of the linear plasma source.

[0057] The power supply preferably supplies power of 5 kW to 50 kW, preferably 10 to 35 kW, per linear meter of the length of the plasma source. When the power is less than 5 kW per linear meter of the plasma source, the presence of carbon is observed in the protective top layer, and when the power exceeds 50 kW per linear meter of the plasma source, arc formation may be observed, which has an adverse effect on the life of the plasma source and / or the quality of the decorative coating.

[0058] The reactive gas preferably contains oxygen or an oxygen-containing derivative, and the latter is preferably selected from the group consisting of ozone, hydrogen peroxide, water and carbon dioxide. According to an embodiment, in order to promote the chemical dissociation of the precursor and control the ion irradiation from the source, the reactive gas can preferably also contain an inert gas such as helium, nitrogen, argon, neon or krypton. If it is present, the inert gas in the reactive gas is 2% to 50% by volume, preferably 3% to 10% by volume, more preferably 4% to 7% by volume. This selection can control the coverage rate of the resulting layer.

[0059] The reactive gas is preferably O2 or an O2-Ar mixture.

[0060] In one embodiment of the present invention, the reactive gas flow rate is 2000 - 5000 sccm per linear meter of the plasma source length.

[0061] The precursor gas containing boron, silicon and hydrogen is uniformly injected into the plasma along the length of the plasma source. The precursor may be injected, for example, between a plurality of electrodes of the pair of electrodes, and / or if there are a plurality of electrode pairs, it may be injected between adjacent electrode pairs. This precursor gas is activated by this plasma. The substrate is placed near the source, and a thin layer is deposited on the substrate from the activated gas.

[0062] The precursor gas flow rate is preferably 125 - 750 sccm per linear meter of the plasma source length. Generally, when the precursor gas consists of a mixture of precursors, the precursor gas flow rate is the sum of the flow rates of the precursors in the mixture.

[0063] The distance between the substrate surface and the opening of the plasma source is preferably 2.0 - 20 cm, more preferably at least 4 - 15 cm, and the plasma is discharged out of the source through this opening.

[0064] Preferably, the ratio of the reactive gas flow rate to the precursor gas flow rate is at least 3, more preferably 3 - 50.

[0065] The precursor gas contains silicon, boron and hydrogen, and may further contain carbon and / or oxygen in particular.

[0066] The precursor gas may contain a single precursor, which means a single precursor, or a mixture of precursors, which means a mixture of different precursors with different compositions. The ratio of the precursors is adjusted so that the boron content in the boron-doped silicon oxide layer with a desired level of boron doping, in particular, is 4 - 12 at% of B.

[0067] According to one embodiment of the present invention, the precursor gas includes at least one precursor containing Si, at least one precursor containing B, and / or at least one precursor containing Si and B. Any of the precursors in the precursor gas may further contain hydrogen. Any of the precursors in the precursor gas may further contain carbon. Any of the precursors may further contain oxygen.

[0068] The temperature of the substrate during the deposition of the protective top layer is 20°C to 60°C, depending on the residence time of the substrate in the plasma and, for example, also on the displacement speed of the substrate under the plasma source.

[0069] In one embodiment of the present invention, the silicon-containing precursor does not contain boron, i.e., does not have boron, and preferably, the precursor is represented by the following formula (I), (II), (III), (IV) or (V). Y1-X-Y2 (I) Or -[Si(CH3) q (H) 2-q -X-] n - (II) Or CH2=C(R1)-Si(R2)(R3)-R4 (III) Or R5-Si(R6)(R7)-R8 (IV) Or CH2=C(R9)C(O)-O-(CH2) p -Si(R 10 )(R 11 )-R 12 (V) Here, in formula (I), X is O or NH, Y1 is -Si(Y3)(Y4)Y5, Y2 is Si(Y 3’ )(Y 4’ )Y 5’ where Y3, Y4, Y5, Y 3’ 、Y 4’ and Y 5’ are each independently H or an alkyl group having up to 10 carbon atoms; here, at most one of Y3, Y4 and Y5 is hydrogen, and Y 3’ 、Y 4’ and Y 5’At most one of them is hydrogen; and the total number of carbon atoms is at most 20. Here, formula (II) is cyclic, where n is 2 to 10, q is 0 to 2, and the total number of carbon atoms is at most 20. Here, in formula (III), R1 is H or an alkyl group, such as -CH3, where R1, R2, and R3 are each independently H, an alkyl group with up to 10 carbon atoms, or an alkoxy group -O-Z, where Z is preferably -C t H 2t+1 and t is 1 to 10. Here, in formula (IV), R5 is H or an alkyl group, such as -CH3, where R6, R7, and R8 are each independently H, an alkyl group with up to 10 carbon atoms, or an alkoxy group -O-Z, where Z is preferably -C t H 2t+1 and t is 1 to 10. Here, in formula (V), R9 is H or an alkyl group, such as -CH3, where p is 0 to 10, where R 10 , R 11 and R 12 are each independently H, an alkyl group with up to 10 carbon atoms, or an alkoxy group -O-Z, where Z is preferably -C t H 2t+1 and t is 1 to 10.

[0070] The alkyl group may be straight-chain or branched-chain, but a straight-chain group is preferred. Such an alkyl group is suitably a methyl group or an ethyl group, but methyl is preferred. It is preferred that all of Y3, Y4, Y5, Y 3’ , Y 4’ or Y 5’ are alkyl groups.

[0071] The alkoxy group may be straight-chain, branched-chain or cyclic, but a straight-chain group is preferred. Such an alkoxy group is suitably a methoxy group or an ethoxy group.

[0072] The silicon-containing precursor of formula I may have six methyl groups. Suitable silicon-containing precursors of formula I are hexamethyldisiloxane (HMDSO), hexamethyldisilazane or tetramethyldisiloxane (TMDSO).

[0073] For the silicon-containing precursor of formula II, n may be 3, or n may be 4, or n may be 5, or n may be 6. Suitable silicon-containing precursors of formula II are octamethylcyclotetrasiloxane. Suitable silicon-containing precursors of formula II are hexamethylcyclotrisilazane.

[0074] For the silicon-containing precursor of formula V, p is 2, and R 10 , R 11 and R 12 may each independently be an alkoxy group, such as methoxy. Suitable silicon-containing precursors of formula V are 3-(trimethoxysilyl)propyl methacrylate. Suitable silicon-containing precursors of formula V are 3-(trimethoxysilyl)propyl acrylate.

[0075] In one embodiment of the present invention, the boron-containing precursor does not contain silicon, which means it does not have Si, and is preferably of formula (VI): R 13 -B(R 14 )(R 15 ) (VI) where R 13 , R 14 and R 15 are each independently H, an alkyl group having up to 10 carbon atoms, or an alkoxy group -O-Z, where Z is preferably -C t H 2t+1 where t is from 1 to 10.

[0076] The alkyl group may be straight-chain or branched-chain, but a straight-chain group is preferred. Such an alkyl group is suitably a methyl group or an ethyl group, with methyl being preferred.

[0077] The alkoxy group may be linear, branched, or cyclic, but a linear group is preferred. Such alkoxy groups are suitably a methoxy group, an ethoxy group, or an isopropoxy group.

[0078] In one embodiment of the present invention, in formula (VI), R 13 , R 14 and R 15 are all ethoxy, or R 13 , R 14 and R 15 are all isopropoxy groups.

[0079] In one embodiment of the present invention, the precursor containing boron and silicon is of formula (VII): R 16 O-B(-OR 17 )(-OR 18 )(VII) Here, R16, R17, and R18 are all independent organosilyl groups, particularly trialkylsilyl groups, alkyl groups having up to 10 carbon atoms. Such trialkyl groups are suitably a trimethylsilyl, triethylsilyl, or diethyl(methyl)silyl group. Such boron and silicon precursors are suitably tris(trimethylsilyl)borate (TTMSB).

[0080] Preferably, the precursors of boron, silicon, and / or both silicon and boron are transported to the plasma source without using a carrier gas. However, in certain embodiments, an additional gas may be used as a carrier gas to introduce the precursor into the plasma chamber.

[0081] Preferably, the precursor is supplied as a liquid, then vaporized, and transported in vaporized form to the plasma source. Preferably, the vaporized precursor is transported to the plasma chamber without using a carrier gas. Alternatively, if necessary, the supply system for the liquid precursor transports the vaporized precursor to the plasma chamber using a carrier gas.

[0082] Preferably, when using a carrier gas, the carrier gas is selected from N2, He or Ar, and / or a mixture of these gases. In one preferred process, a single carrier gas is used. This is most preferably He or Ar.

[0083] Preferably, when using a carrier gas, the amount of the carrier gas is about 5% to about 1500% carrier gas based on the total flow rate of all silicon and boron precursors, preferably about 10% to about 1000% additional gas, more preferably 20% to 750%, such as 25% to 500%, such as 500, 450, 400, 350, 300, 250, 200, 175, 150, 125, 100, 90, 80, 75, 70, 60, 50, 40, 35, 30, or 25% carrier gas.

[0084] The precursor may be gaseous at room temperature and room pressure or a vaporized liquid.

[0085] The following different precursor flow rates are necessary to obtain a high dynamic deposition rate of about 20 - 500 nm.m / min. Generally, the higher the precursor flow rate, the higher the power applied to the plasma source.

[0086] In one embodiment of the present invention, the total flow rate of the silicon-containing precursor is 10 - 500 sccm (standard cubic centimeters per minute) per linear meter of plasma length, preferably 50 - 500 sccm or 50 - 400 sccm per linear meter of plasma length.

[0087] The unit <<nm.m / min>> used in this application represents the deposition rate. This unit is a combination of SI units typically used to characterize the deposition rate of a dynamic or continuous coating process, i.e., a process in which the substrate moves continuously within the deposition apparatus. The deposition rate of such a deposition apparatus is generally referred to as <<dynamic deposition rate>>, which is used to represent the deposition rate of the decorative coating apparatus itself regardless of the speed at which the substrate moves within the deposition apparatus.

[0088] In one embodiment of the present invention, the total flow rate of the boron-containing precursor is 10 to 500 sccm (standard cubic centimeters per minute) per linear meter of plasma length, preferably 50 to 500 sccm or 50 to 400 sccm per linear meter of plasma length.

[0089] In one embodiment of the present invention, the total flow rate of the precursor containing silicon and boron is 10 to 750 sccm (standard cubic centimeters per minute) per linear meter of plasma length, preferably 50 to 750 sccm or 50 to 600 sccm per linear meter of plasma length.

[0090] In some cases, stage c) may include adding an additional precursor to the substrate in order to further improve, for example, mechanical and / or chemical durability and / or to increase the refractive index of the boron-doped silicon oxide protective top layer, including certain additional oxides such as titanium oxide or zirconium oxide.

[0091] According to one embodiment of the present invention, the boron-doped silicon oxide protective top layer contains at least 80 wt% silicon dioxide SiO2.

[0092] According to one embodiment of the present invention, the boron-doped silicon oxide protective top layer contains up to 15 wt% titanium oxide, zirconium oxide, or a mixture thereof.

[0093] The present invention is defined in the appended independent claims. Preferred embodiments are defined in the dependent claims.

[0094] It should be noted that the present invention relates to all possible combinations of the features described in the claims or the above embodiments.

[0095] In one embodiment of the present invention, the decorative coating includes a metal coating between the substrate and the protective top layer. Preferably, the metal coating is deposited on the polymer substrate before depositing the protective top layer. The metal coating may include one or more metal layers.

[0096] The deposition of the metal coating is preferably carried out using a physical vapor deposition process, advantageously using a conventional magnetron sputtering process well known in the art. Representative descriptions of sputter deposition processes and apparatuses are incorporated herein by reference, for example, in US4204942A, US4948087A, US5589280A, US20110275262A1, KR20120026936A, and EP0546470A1. In other embodiments of the present invention, the deposition of one or more thin metal layers is carried out using deposition such as thermal evaporation or electron beam evaporation. The material deposited by any physical vapor deposition technique may be advantageously selected from Ag, Cu, Al, Cr, Ti or silicon, or metal alloys such as NiCr alloy or NiCrW alloy.

[0097] In one embodiment of the present invention, in order to achieve the desired level of opacity and the level of reflectivity required for a particular application, the thickness of the metal coating is advantageously 20 nm to 300 nm, and in particular, in order to achieve a metallic appearance, it is advantageously 30 nm to 150 nm, more advantageously 40 nm to 120 nm.

[0098] In a preferred embodiment of the present invention, the metal coating includes one reflective layer. The reflective layer is the top layer of the metal coating, that is, the layer located farthest from the substrate surface. Therefore, the reflective layer is visible through any subsequent layer, particularly the protective top layer, and bears a large degree of the metallic appearance imparted to the substrate by the metal coating. In an advantageous embodiment of the present invention, the reflective layer is an aluminum layer. The reflective layer may have a thickness of 10 to 25 nm and may particularly be the thickest layer in the metal coating.

[0099] In certain embodiments of the present invention, the target used in magnetron sputtering may be a circular target or a linear target, and the linear target is particularly useful for continuous coating processes. The target used may be, for example, a metal target containing a metal selected from Ag, Cu, Al, Cr, Ti, or a silicon-based target, or a metal alloy target containing, for example, a NiCr alloy or a NiCrW alloy.

[0100] In an advantageous embodiment, the metal coating includes a metal base layer in direct contact with the polymer substrate in addition to the reflective layer. The metal base layer can enhance the adhesion of the metal coating to the polymer substrate. The material of the metal base layer may be different from that of the reflective layer and may be selected from NiCr. The NiCr metal base layer may be composed of an alloy of Ni and Cr with a Ni / Cr weight ratio of 99 / 1 to 50 / 50, preferably 80 / 20. The metal base layer is preferably in direct contact with the metal reflective layer. The inventors have found that such a metal base layer further improves the mechanical and chemical resistance of the decorative coating.

[0101] In another embodiment, the decorative coating has a carbon adhesion layer between the metal coating and the polymer substrate. The carbon adhesion layer may be in direct contact with the metal coating. The carbon adhesion layer may be in direct contact with the polymer substrate. The carbon adhesion layer may have a thickness of 4 to 10 nm. Figure 3 shows a polymer substrate (10), the carbon adhesion layer (3) is in direct contact with the substrate, the metal coating (2) is in direct contact with the adhesion layer, and the protective top layer (1) is in direct contact with the metal coating (2).

[0102] Depositing a carbon adhesion layer on a polymer substrate using an additional linear hollow cathode type plasma source, which: a. Provide an additional linear hollow cathode type plasma source having at least one pair of hollow cathode plasma generating electrodes connected to an AC, DC, or DC pulse generator for depositing the carbon adhesion layer on the polymer substrate; b. Preferably, a plasma generation gas selected from N2, He, Ar, or a mixture of two or more thereof is injected into the electrodes of the additional plasma source at a flow rate of 1000 to 5000 sccm, preferably 1500 to 4500 sccm, more preferably 2000 to 4000 sccm per linear meter of the length of the additional plasma source; c. Electric power of 2 kW to 20 kW per linear meter of the length of this additional plasma source is applied to the additional plasma source; d. For example, a gaseous precursor of carbon selected from CH4, C2H4, C2H2, C3H8, C4H 10 is injected at a flow rate of 50 to 600 sccm, preferably 100 to 500 sccm, more preferably 200 to 400 sccm per linear meter of the length of the additional plasma source. This gaseous precursor is preferably injected into the plasma between at least the electrodes of each electrode pair of the additional plasma source; e. This substrate is exposed to the plasma of the additional plasma source, thereby depositing a carbon adhesion layer composed of a carbon-based layer on the active surface of the substrate.

[0103] The inventors have found that the carbon adhesion layer improves the chemical resistance of the decoration.

[0104] In one embodiment, the additional plasma source is connected to a generator that supplies an AC or pulsed DC current having a frequency of 5 to 150 kHz, or alternately 5 to 100 kHz.

[0105] In one embodiment of the present invention, the distance between the substrate surface and the outlet of the additional plasma source is 50 to 150 mm, preferably 60 to 120 mm, more preferably 80 to 100 mm.

[0106] In one embodiment of the present invention, the deposition of the carbon adhesion layer is carried out under a pressure of 0.005 to 0.050 Torr, more preferably 0.010 to 0.040 Torr, more preferably 0.020 to 0.030 Torr.

[0107] In certain embodiments of the present invention, the hybrid ratio sp3 / sp2 of the carbon adhesion layer is 0.6 to 0.8.

[0108] In an advantageous embodiment of the present invention, a barrier layer, such as silicon nitride, is directly deposited on the topmost metal layer in order to protect the metal layer from oxidation by deposition of a protective top layer. This barrier layer may be in direct contact with the protective top layer.

[0109] In certain embodiments of the present invention, magnetron sputtering deposition of the metal layer may be performed by applying a power of 1 kW to 20 kW per linear meter of the target.

[0110] In certain embodiments of the present invention, the plasma generating gas used for physical vapor deposition of the metal layer is preferably argon.

[0111] In certain embodiments of the present invention, physical vapor deposition is preferably carried out under a pressure of 0.002 Torr to 0.050 Torr, more preferably 0.003 Torr to 0.020 Torr, and even more preferably 0.004 Torr to 0.010 Torr.

[0112] In certain embodiments, deposition of the metal layer by vapor deposition is carried out using an ingot of the same material as the target for magnetron sputtering.

[0113] The metal coating mainly provides the resulting coated substrate with a decorative metallic appearance. The metallic appearance may be enhanced by the protective top layer.

[0114] In certain embodiments of the present invention, the polymer substrate may be a homogeneous sheet of polymer, but other shapes, such as three-dimensional shapes, are also possible.

[0115] In certain embodiments of the present invention, the polymer substrate may include acrylic polymers, polymethyl methacrylate (PMMA) and its copolymers, CR-39 or allyl diglycol carbonate (ADC), polycarbonate, polypropylene (PP), biaxially oriented polypropylene (BOPP), polyethylene (PE), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polystyrene, cyclic olefin copolymers (COC’s), polyethylene terephthalate glycol (PETG), and combinations of the above elements. The polymer substrate of the present invention is a type of copolymer or physical mixture of polymers made from materials having both thermoplastic and elastomeric properties, usually plastics and rubbers, and may include thermoplastic elastomers (TPEs) sometimes called thermoplastic rubbers. In particular, this polymer substrate may have styrene block copolymers, TPS (TPE-s), thermoplastic polyolefin elastomers, TPO (TPE-o), thermoplastic vulcanizates, TPV (TPE-v or TPV), thermoplastic polyurethanes, TPU (TPU), thermoplastic copolyesters, TPC (TPE-E), thermoplastic polyamides, and TPA (TPE-A).

[0116] In certain embodiments of the present invention, the polymer substrate may be a thin polymer film with a thickness of 5 μm to 300 μm, alternately 10 μm to 250 μm, alternately 20 μm to 200 μm, alternately 25 μm to 15 μm. These polymer thin films may be processed by a roll-to-roll method.

[0117] In the following examples, polymer substrates of a mixture of polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS), and polymer substrates of ABS only were used. Similar results were obtained from both substrates. These substrates have a dull appearance and the glossiness of these uncoated substrates is low. It was found that the gloss increases by depositing SiO2 on these substrates.

[0118] Examples 1 and 3 below are comparative examples, and Examples 2 and 4 are according to the present invention.

[0119] In Example 1, the SiO2 layer was deposited by magnetron sputtering from a silicon target in an Ar / O2 atmosphere. The thickness of the SiO2 layer was 130 nm.

[0120] In Example 2, a boron-doped silicon oxide (SiO2:B) layer was deposited by hollow cathode PECVD using a mixture of O2 reactive gas and TTMSB and TEB as precursor gases. The thickness of the SiO2 layer was 130 nm.

[0121] In Example 3, a metal coating consisting of a 4-nm NiCr alloy first adhesion metal layer was deposited onto a polymer substrate, and then a 17-nm-thick aluminum reflective metal layer was deposited. A Si3N4 barrier layer was deposited on this metal coating. Both metal layers were deposited by magnetron sputtering from the corresponding metal targets in an Ar atmosphere. A 9 - 10-nm Si3N4 layer was deposited by magnetron sputtering from a Si target in an Ar / N2 atmosphere. Then, a SiO2 layer similar to that in Example 1 was deposited.

[0122] In Example 4, a metal coating consisting of a 4-nm NiCr alloy first adhesion metal layer was deposited onto a polymer substrate, and then a 17-nm-thick aluminum reflective metal layer was deposited. A Si3N4 barrier layer was deposited on this metal coating. Both metal layers were deposited by magnetron sputtering from the corresponding metal targets in an Ar atmosphere. A 9 - 10-nm Si3N4 layer was deposited by magnetron sputtering from a Si target in an Ar / N2 atmosphere. Then, a SiO2:B layer similar to that in Example 2 was deposited.

[0123] In Example 5, a metal coating consisting of a 4-nm NiCr alloy first adhesion metal layer was deposited on a polymer substrate, and then a 17-nm-thick aluminum reflective metal layer was deposited. A Si3N4 barrier layer was deposited on this metal coating. Both metal layers were deposited by magnetron sputtering from the corresponding metal targets in an Ar atmosphere. A 9-10 nm Si3N4 layer was deposited by magnetron sputtering from a Si target in an Ar / N2 atmosphere. Then, a polyurethane-based lacquer layer was spray-coated on the sputter-deposited layer.

[0124] In Example 6, a metal coating consisting of a 10-nm first adhesion carbon layer was deposited on a polymer substrate by hollow cathode PECVD, and then a 17-nm-thick aluminum reflective metal layer was deposited. A Si3N4 barrier layer was deposited on the metal coating. This metal layer was deposited by magnetron sputtering from an aluminum metal target in an Ar atmosphere. A 9-10 nm Si3N4 layer was deposited by magnetron sputtering from a Si target in an Ar / N2 atmosphere. Then, a 130-nm-thick undoped SiO2 layer was deposited by hollow cathode PECVD using O2 reactive gas and TMDSO (tetramethyldisiloxane).

[0125] The clockmeter test is a dry friction test performed using a 15-mm-diameter cylindrical finger and a 9-μm, 1200-grit sandpaper pad as described in ISO 11998:1998 standard. In the present invention, 10 double strokes corresponding to 20 cycles are performed on a dried sample without adding liquid. The total weight of the polishing pad is 900 g.

[0126] Gloss measurement was performed according to ASTM standard D523-2014 at a specific angle of 60° using a certified black glass standard with a gloss of 96.0 at 60°.

[0127] The relative decrease in gloss, expressed as a percentage of the initial gloss, was determined after the clockmeter test.

[0128] In Examples 1 and 5, the gloss decreased by 30-40%. In Examples 2 and 4, the gloss decreased by 3% and 1-2% respectively. In Example 6, the gloss decreased by 3-4%.

[0129] Examples 2, 4 and 6 were subjected to a chemical durability test, namely a copper-accelerated acetic acid salt spray test (CASS) according to ISO9227-2006 standard. In Example 6, delamination of the coating already occurred after 24 hours of the test, and in Examples 2 and 4, a decrease in gloss was observed after 48 hours, but the decrease level of gloss was less than 30%. Thus, boron-doped SiO2 has extremely good resistance to chemical attack.

Claims

1. A polymer substrate having a decorative coating including a protective top layer of boron-doped silicon oxide, wherein the boron-doped silicon oxide contains Si, O, B, and H, the boron content is 4 to 12 atomic %, and it contains OH groups.

2. The protective top layer contains at least 80% by weight of SiO ２ The polymer substrate according to claim 1, characterized in that it contains

3. The polymer substrate according to any one of Claims 1 or 2, wherein the O / Si atomic ratio of the protective top layer is 1.9 to 2.

6.

4. The polymer substrate according to any one of Claims 1 to 3, wherein the protective top layer does not contain carbon.

5. The polymer substrate according to any one of Claims 1 to 4, wherein the thickness of the protective top layer is at least 80 nm and / or at most 400 nm.

6. The polymer substrate according to any one of Claims 1 to 5, wherein the protective top layer is in direct contact with the polymer substrate.

7. The polymer substrate according to any one of Claims 1 to 6, wherein the decorative coating further includes a metal coating including one or more metal layers between the substrate and the protective top layer.

8. The polymer substrate according to Claim 7, wherein the metal coating has a thickness of 20 nm to 300 nm.

9. The polymer substrate according to any one of Claims 7 or 8, wherein the metal coating includes a reflective metal layer of a metal selected from Ag, Cu, Al, Cr, Zr, Ti, Si, or a NiCrW alloy, and an optional NiCr metal base layer in direct contact with the substrate and the reflective metal layer.

10. The polymer substrate according to any one of Claims 7 to 9, wherein the decorative coating further includes a carbon adhesion layer between the substrate and the metal coating.

11. The decorative coating is Si that is in direct contact with the metal coating and the protective top layer. ３ N ４ The polymer substrate according to any one of claims 7 to 10, characterized by including a barrier layer of.

12. A method for depositing a decorative coating including a boron-doped silicon oxide protective top layer on a polymer substrate, wherein the protective top layer contains Si, O, B, and OH groups, and the boron content is 4 to 12 atomic %, a. providing a polymer substrate, b. providing a linear hollow cathode type plasma source, the plasma source including at least a pair of hollow cathode plasma generating electrodes having a length and connected to an AC, DC, or DC pulse generator power source for depositing the protective top layer on the substrate. c. Inject a plasma-generating reactive gas containing oxygen into the electrodes of the plasma source at a flow rate of 125 to 750 sccm per linear meter of the length of the plasma source; d. Apply power of 10 to 50 kW per linear meter of the length of the plasma source to the plasma source to generate plasma, and e. Inject a precursor gas containing boron, silicon, and hydrogen at a flow rate of 500 to 2500 sccm per linear meter of the length of the plasma source, inject the precursor gas into the plasma toward at least between the electrodes of each electrode pair of the plasma source, and expose the substrate to the plasma of the plasma source, thereby depositing the protective top layer on the polymer substrate, the method comprising the steps.

13. The method according to claim 12, wherein the precursor gas comprises at least one precursor containing Si, at least one precursor containing B, and / or at least one precursor containing Si and B.

14. The reactive gas is O ２ or an O ２ -Ar mixture, and the method according to any one of claims 12 or 13, characterized in that.

15. The method according to any one of claims 12 to 14, wherein the flow rate of the reactive gas is 200 to 500 sccm per linear meter of the length of the plasma source.

16. The method according to any one of claims 12 to 15, wherein the precursor gas comprises at least one precursor selected from a silicon-containing precursor, a boron-containing precursor, and / or a precursor containing silicon and boron, and the total flow rate of each precursor is 10 to 500 sccm.

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