Vehicle plastic part surface hardening coating and preparation method thereof

Abstract

According to the method, organic silicon with a short saturated carbon chain and organic silicon with an epoxy group, an unsaturated carbon-carbon bond or an amino group serve as monomers and serve as raw materials, plasma excitation is carried out, and the surface hardening coating of the automobile plastic part can be obtained by adjusting the plasma discharge power, the duty ratio and the bias voltage. The coating with excellent hardness and adhesive force is prepared and obtained.

Description

Technical Field

[0001] The present invention belongs to the field of surface hardening of plastic part substrates for automotive applications, and particularly relates to a surface hardening coating for automotive plastic parts and a preparation method thereof. Background Art

[0002] With the continuous development of automotive technology, higher requirements have been put forward for the safety, lightweight and appearance of vehicles. Plastic products also have more and more applications in automobiles due to their excellent optical properties, aging resistance and easy molding characteristics, such as door panels, instrument panels, bumpers, exhaust manifolds, lamp housings, interior parts, etc. However, most plastic products have low hardness and are easily scratched during production and application. Therefore, it is very necessary to perform some hardening protection treatments on the plastic substrate surface.

[0003] Currently, hardening the plastic surface through a photocuring process is an effective method. CN111218020A discloses a preparation method of a hardening material. Polyurethane acrylate resin oligomers and polymers with different functionalities are added to an ester solvent, and after stirring and reacting, a UV initiator is added, and stirring is continued to obtain a hardening coating. This coating not only requires the use of organic solvents, but also has appearance problems such as leveling when processed onto the substrate by spraying or curtain coating.

[0004] Plasma enhanced chemical vapor deposition (PECVD) is a new technology that can react at low temperatures through plasma excitation. Depositing a hardening film layer on the surface of plastics by PECVD not only has uniform and efficient deposition, but also has a dense structure, is solvent-free and environmentally friendly, and has broad application prospects. Summary of the Invention

[0005] The specific implementation mode of the present invention uses silicone as a raw material to form a coating with excellent hardness and adhesion on the surface of automotive plastic parts through a plasma process. The specific scheme is as follows:

[0006] A surface hardening coating for automotive plastic parts, wherein the coating is formed by depositing plasma of at least one of the structures shown in formula (1), formula (2) or formula (3) and a silicone monomer of the structure shown in formula (4) on the surface of an automotive plastic part substrate,

[0007]

[0008] In formula (1), R1 is a hydrogen atom, an alkyl group with 1 - 4 carbon atoms, an alkoxy group with 1 - 4 carbon atoms or an acyloxy group with 1 - 4 carbon atoms, R2 is an alkyl group with 1 - 4 carbon atoms, an alkoxy group with 1 - 4 carbon atoms or an alkanoyloxy group with 1 - 4 carbon atoms, and n is an integer from 3 to 10;

[0009] In formula (2), R3, R4 and R5 are each independently selected from a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkanoyloxy group having 1 to 4 carbon atoms, and R6 is an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkanoyloxy group having 1 to 4 carbon atoms;

[0010] In formula (3), R7, R8 and R9 are each independently selected from a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkanoyloxy group having 1 to 4 carbon atoms, and R 10 is an alkyl group having 1 to 4 carbon atoms or an acyl group having 1 to 4 carbon atoms, and m is an integer from 2 to 100;

[0011] In formula (4), R 11 , R 12 and R 13 are each independently selected from a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and R 14 is an organic group having a carbon-carbon double bond, a carbon-carbon triple bond, an epoxy group, or an amino group, and L is a linking moiety;

[0012] The hardness of the coating is tested to be above 1.5 GPa using a KLA nanoindenter, and the adhesion of the coating is tested to be above 3B according to the ASTM D3359 standard.

[0013] Optionally, the hardness of the coating is tested to be above 2.8 GPa using a KLA nanoindenter, and the adhesion of the coating is tested to be above 5B according to the ASTM D3359 standard.

[0014] Optionally, R1 is methyl or ethyl, and R2 is methyl or ethyl.

[0015] Optionally, the organosilicon having the structure shown in formula (1) is at least one of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, decamethylcyclopentasiloxane, or dodecamethylcyclohexasiloxane.

[0016] Optionally, the organosilicon having the structure shown in formula (2) is dimethylsiloxane, tetraethoxysilane, tetramethoxysilane, tetrabutyl orthosilicate, tetramethyl orthosilicate, tetraethyl orthosilicate, tetraisopropyl orthosilicate, methyltripropoxysilane, triethoxysilane, methyltriethoxysilane, dimethoxydimethylsilane, di-tert-butoxydimethoxysilane

[0017] Optionally, the organosilicon having the structure shown in formula (3) is at least one of 1,1,3,3-tetramethyl-1,3-disiloxane, bis(trimethylsiloxy)methylsilane, decamethyltetrasiloxane, octamethyltrisiloxane, hexamethyldisiloxane, tetramethyldisiloxane, hexaethyldisiloxane, 3H,5H-octamethyltetrasiloxane.

[0018] Optionally, the silicone having the structure shown in formula (4) has the structure shown in formula (5) below,

[0019]

[0020] In formula (5), R 15 is an alkylene group of C1-C4, and R 16 is a group of formula (6), (7), (8), (9), vinyl or amino group,

[0021]

[0022]

[0023] In formula (9), R 17 , R 18 and R 19 are each independently selected from a hydrogen atom or an alkyl group of C1-C4.

[0024] Optionally, the R 17 and R 18 are hydrogen atoms, and the R 19 is a hydrogen atom or a methyl group.

[0025] Optionally, the silicone having the structure shown in formula (4) is at least one of 3-(methacryloyloxy)propyltrimethoxysilane, γ-methacryloyloxypropyltriisopropoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, γ-methacryloyloxypropyltris(trimethylsiloxy)silane, 3-methacryloyloxypropyltriethoxysilane, 3-(methacryloyloxy)propylmethyldiethoxysilane, 3-(acryloyloxy)propyltrimethoxysilane, 3-(acryloyloxy)methyldimethoxysilane, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane, γ-glycidyletheroxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltriethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, 3-(2,3-epoxypropoxy)propylmethyldiethoxysilane, allyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris(2-methoxyethoxy)-silane, vinyltriisopropoxysilane, methylvinyldimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, diethylenetriaminepropyltrimethoxysil, 3-aminopropylmethyldimethoxysilane.

[0026] Optionally, the thickness of the coating is 1500 - 3500 nm.

[0027] Optionally, the vehicle plastic part is a door panel, dashboard, bumper, exhaust manifold, lamp housing or interior part.

[0028] A method for preparing a surface hardening coating for a vehicle plastic part as described above, comprising the following steps:

[0029] Provide a vehicle plastic part substrate, and place the vehicle plastic part substrate in a plasma deposition chamber provided with a bias voltage;

[0030] Introduce the vapor of at least one of the structures shown in formula (1), formula (2) or formula (3) and the organosilicon monomer of the structure shown in formula (4) into the reaction chamber, introduce at least one of oxygen or inert gas, maintain the pressure of the reaction chamber not greater than 100 mT, turn on the pulsed plasma discharge and the bias voltage, and deposit the coating by adjusting the power, duty cycle and bias voltage of the pulsed plasma discharge.

[0031] Optionally, the power of the pulsed plasma discharge is 200 W to 1000 W, the duty cycle is 5 to 50%, and the bias voltage is 200 V to 1000 V.

[0032] Optionally, the power of the pulsed plasma discharge is 400 W to 700 W, the duty cycle is 30 to 40%, and the bias voltage is 450 V to 600 V.

[0033] A vehicle plastic part having at least a part of its surface with the surface hardening coating for a vehicle plastic part as described above.

[0034] In the specific embodiment of the present invention, the surface hardening coating for a vehicle plastic part, the coating is formed by depositing plasma of organosilicon with short saturated carbon chains and organosilicon with epoxy groups, unsaturated carbon-carbon bonds or amino groups on the surface of a vehicle plastic part substrate. During the preparation process, by adjusting the power, duty cycle and bias voltage of the plasma discharge, the coating with excellent hardness and adhesion can be obtained. Specific Embodiment

[0035] The specific embodiment of the present invention provides a surface hardening coating for a vehicle plastic part. The coating is formed by depositing plasma of at least one of the structures shown in the following formula (1), formula (2) or formula (3) and the organosilicon monomer of the structure shown in the following formula (4) on the surface of a vehicle plastic part substrate.

[0036]

[0037] In formula (1), R1 is a hydrogen atom, an alkyl group with 1 to 4 carbon atoms, an alkoxy group with 1 to 4 carbon atoms or an alkanoyloxy group with 1 to 4 carbon atoms, R2 is an alkyl group with 1 to 4 carbon atoms, an alkoxy group with 1 to 4 carbon atoms or an alkanoyloxy group with 1 to 4 carbon atoms, and n is an integer from 3 to 10;

[0038] In formula (2), R3, R4 and R5 are each independently selected from a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkanoyloxy group having 1 to 4 carbon atoms, and R6 is an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkanoyloxy group having 1 to 4 carbon atoms;

[0039] In formula (3), R7, R8 and R9 are each independently selected from a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkanoyloxy group having 1 to 4 carbon atoms, and R 10 is an alkyl group having 1 to 4 carbon atoms or an acyl group having 1 to 4 carbon atoms, and m is an integer from 2 to 100. In some specific embodiments, m is an integer from 2 to 10;

[0040] In formula (4), R 11 , R 12 and R 13 are each independently selected from a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and R 14 is an organic group having a carbon-carbon double bond, a carbon-carbon triple bond, an epoxy group, or an amino group, and L is a connecting moiety;

[0041] The hardness of the coating is tested to be above 1.5 GPa using a KLA nanoindenter, and the adhesion of the coating is tested to be above 3B according to the ASTM D3359 standard.

[0042] For the surface hardening coating of the automotive plastic part in the specific embodiments of the present invention, in some specific embodiments, the hardness of the coating is tested to be above 2.0 GPa using a KLA nanoindenter, further above 2.8 GPa, and the adhesion of the coating is tested to be above 4B according to the ASTM D3359 standard, further above 5B.

[0043] For the surface hardening coating of the automotive plastic part in the specific embodiments of the present invention, in some specific embodiments, the alkyl group having 1 to 4 carbon atoms is, for example, methyl, ethyl, propyl or butyl, the alkoxy group having 1 to 4 carbon atoms is, for example, methoxy, ethoxy, propoxy or butoxy, and the alkanoyloxy group having 1 to 4 carbon atoms is, for example, formyloxy, acetyloxy, propionyloxy or butyryloxy.

[0044] For the surface hardening coating of the automotive plastic part in the specific embodiments of the present invention, in some specific embodiments, the alkyl group having 1 to 4 carbon atoms is methyl, isopropyl or isobutyl, the alkoxy group having 1 to 4 carbon atoms is methoxy, isopropoxy or isobutoxy, and the alkanoyloxy group having 1 to 4 carbon atoms is formyloxy, isopropylcarbonyloxy, or isobutylcarbonyloxy.

[0045] The surface hardening coating for vehicle plastic parts in the specific embodiments of the present invention. In some specific embodiments, the silicone having the structure shown in formula (1) is at least one of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, decamethylcyclopentasiloxane, or dodecamethylcyclohexasiloxane.

[0046] The surface hardening coating for vehicle plastic parts in the specific embodiments of the present invention. In some specific embodiments, the silicone having the structure shown in formula (2) is dimethylsiloxane, tetraethoxysilane, tetramethoxysilane, tetrabutyl orthosilicate, tetramethyl orthosilicate, tetraethyl orthosilicate, tetraisopropyl orthosilicate, methyltripropoxysilane, triethoxysilane, methyltriethoxysilane, dimethoxydimethylsilane, or di-tert-butoxydimethoxysilane.

[0047] The surface hardening coating for vehicle plastic parts in the specific embodiments of the present invention. In some specific embodiments, the silicone having the structure shown in formula (3) is at least one of 1,1,3,3-tetramethyl-1,3-disiloxane, bis(trimethylsilyloxy)methylsilane, decamethyltetrasiloxane, octamethyltrisiloxane, hexamethyldisiloxane, tetramethyldisiloxane, hexaethyldisiloxane, or 3H,5H-octamethyltetrasiloxane.

[0048] The surface hardening coating for vehicle plastic parts in the specific embodiments of the present invention. In some specific embodiments, the silicone having the structure shown in formula (4) has the structure shown in formula (5).

[0049]

[0050] In formula (5), R 15 is an alkylene group of C1-C4, and R 16 is a group of formula (6), (7), (8), (9), vinyl, or amino group.

[0051]

[0052] In formula (9), R 17 , R 18 and R 19 are each independently selected from a hydrogen atom or an alkyl group of C1-C4.

[0053] The surface hardening coating for vehicle plastic parts in the specific embodiments of the present invention. In some specific embodiments, R 17 and R 18 are hydrogen atoms, and R 19 is a hydrogen atom or a methyl group.

[0054] The surface hardening coating for vehicle plastic parts in the specific embodiments of the present invention. In some specific embodiments, the silicone with the structure shown in formula (4) is at least one of 3-(methacryloyloxy)propyltrimethoxysilane, γ-methacryloyloxypropyltriisopropoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, γ-methacryloyloxypropyltris(trimethylsiloxy)silane, 3-methacryloyloxypropyltriethoxysilane, 3-(methacryloyloxy)propylmethyldiethoxysilane, 3-(acryloyloxy)propyltrimethoxysilane, 3-(acryloyloxy)methyldimethoxysilane, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane, γ-glycidoxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltriethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, 3-(2,3-epoxypropoxy)propylmethyldiethoxysilane, allyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris(2-methoxyethoxy)-silane, vinyltriisopropoxysilane, methylvinyldimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, diethylenetriaminepropyltrimethoxysil, 3-aminopropylmethyldimethoxysilane.

[0055] The surface hardening coating for vehicle plastic parts in the specific embodiments of the present invention. In some specific embodiments, the mass ratio of the silicone with the structures shown in formula (1), formula (2) and formula (3) to the silicone with the structure shown in formula (4) is 1:10 to 10:1. In some specific embodiments, the mass ratio of the silicone with the structures shown in formula (1), formula (2) and formula (3) to the silicone with the structure shown in formula (4) is 1:5 to 5:1. Specifically, for example, it can be 1:5, 2:5, 3:5, 4:5, 1:1, 5:4, 5:3, 5:2 or 5:1, etc.

[0056] The surface hardening coating for vehicle plastic parts in the specific embodiments of the present invention. In some specific embodiments, the thickness of the coating is 1500 - 3500 nm. Specifically, for example, it can be 1500 nm, 1600 nm, 1700 nm, 1800 nm, 1900 nm, 2000 nm, 2100 nm, 2200 nm, 2300 nm, 2400 nm, 2500 nm, 2600 nm, 2700 nm, 2800 nm, 2900 nm, 3000 nm, 3100 nm, 3200 nm, 3300 nm, 3400 nm or 3500 nm, etc.

[0057] The surface hardening coating for vehicle plastic parts in the specific embodiments of the present invention. In some specific embodiments, the vehicle plastic parts are door panels, instrument panels, bumpers, exhaust manifolds, lamp housings or interior parts, etc.

[0058] The specific embodiments of the present invention also provide a preparation method for the surface hardening coating of the vehicle plastic parts as described above, including the following steps:

[0059] Provide a substrate of vehicle plastic parts, and place the substrate of vehicle plastic parts in a plasma deposition chamber provided with a bias voltage;

[0060] Introduce the vapor of at least one of the structures shown in formula (1), formula (2) or formula (3) and the organosilicon monomer of the structure shown in formula (4) into the reaction chamber, introduce at least one of oxygen or inert gas, maintain the pressure of the reaction chamber not greater than 100 mT, turn on the pulsed plasma discharge and the bias voltage, and deposit the coating by adjusting the power, duty cycle and bias voltage of the pulsed plasma discharge.

[0061] In the preparation method of the surface hardening coating for vehicle plastic parts of the present invention, by using organosilicon with short saturated carbon chains in the structures shown in formula (1), formula (2) or formula (3) and organosilicon with epoxy groups, unsaturated carbon-carbon bonds or amino groups in the structure shown in formula (4) as raw materials, introducing at least one of oxygen or inert gas, especially when introducing oxygen, turning on the pulsed plasma discharge and the bias voltage, and by adjusting the power, duty cycle and bias voltage of the pulsed plasma discharge, a coating with a hardness above 1.5 GPa, further above 2.0 GPa, and even further above 2.8 GPa, and an adhesion above 3B, further above 4B, and even further above 5B can be deposited.

[0062] In the preparation method of the surface hardening coating for vehicle plastic parts of the present invention, in some specific embodiments, the power of the pulsed plasma discharge is 200 W - 1000 W, the duty cycle is 5 - 50%, and the bias voltage is 200 V - 1000 V. In some specific embodiments, the power of the pulsed plasma discharge is 400 W - 700 W, specifically, for example, it can be 400 W, 500 W, 600 W or 700 W, etc., the duty cycle is 30 - 40%, specifically, for example, it can be 30%, 35% or 40%, etc., and the bias voltage is 450 V - 600 V, specifically, for example, it can be 450 V, 500 V, 550 V or 600 V, etc.

[0063] The preparation method of the surface hardening coating for vehicle plastic parts of the present invention. In some specific embodiments, the organosilicon monomers with the structures shown in formula (1) and formula (2) are mixed and introduced into the reaction chamber at a flow rate of 5 - 3000 μl / min, further preferably 50 - 500 μl / min. Specific examples can be 50 μl / min, 100 μl / min, 150 μl / min, 200 μl / min, 250 μl / min, 300 μl / min, 350 μl / min, 400 μl / min, 450 μl / min or 500 μl / min, etc.

[0064] The preparation method of the surface hardening coating for vehicle plastic parts of the present invention. In some specific embodiments, the flow rate of the introduced oxygen is 50 - 500 sccm. Specific examples can be 50 sccm, 100 sccm, 150 sccm, 200 sccm, 250 sccm, 300 sccm, 350 sccm, 400 sccm, 450 sccm or 500 sccm, etc. In some specific embodiments, the flow rate of the inert gas is 0 - 500 sccm. Specific examples can be 50 sccm, 100 sccm, 150 sccm, 200 sccm, 250 sccm, 300 sccm, 350 sccm, 400 sccm, 450 sccm or 500 sccm, etc.

[0065] The preparation method of the surface hardening coating for vehicle plastic parts of the present invention. In some specific embodiments, only oxygen is introduced and no other inert gas is introduced, which is beneficial to further improve the hardness of the coating. In some specific embodiments, only the inert gas is introduced. In some specific embodiments, both oxygen and the inert gas are introduced simultaneously.

[0066] The preparation method of the surface hardening coating for vehicle plastic parts of the present invention. In some specific embodiments, the inert gas is nitrogen, argon, helium, etc.

[0067] The preparation method of the surface hardening coating for vehicle plastic parts of the present invention. In some specific embodiments, the temperature in the reaction chamber is controlled at 20°C - 80°C. Specific examples can be 20°C, 30°C, 40°C, 50°C, 60°C, 70°C or 80°C, etc. The gasification temperature of the monomer is 50°C - 180°C. Specific examples can be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C or 180°C, etc., and the gasification occurs under vacuum conditions.

[0068] The preparation method of the surface hardening coating for vehicle plastic parts in the specific embodiments of the invention. In some specific embodiments, the pulse plasma discharge time is 1000s to 36000s, and specifically, for example, it can be 1000s, 2000s, 3000s, 4000s, 5000s, 6000s, 7000s, 8000s, 9000s, 10000s, 15000s, 20000s, 25000s, 30000s, 36000s, and so on.

[0069] The preparation method of the surface hardening coating for vehicle plastic parts in the specific embodiments of the invention. In some specific embodiments, to further improve the bonding force of the silicone-based hydrophobic film layer, in some specific embodiments, the substrate is pretreated with continuous plasma before coating. The specific pretreatment methods are, for example, evacuating to 10 to 200 mTorr and introducing a mixed gas of one or several of the gases nitrogen, argon, helium, or oxygen, and then starting the plasma discharge to pretreat the substrate, or using methods such as heat, oxygen, or high-energy radiation, and so on.

[0070] The preparation method of the surface hardening coating for vehicle plastic parts in the specific embodiments of the invention. In some specific embodiments, the plasma discharge method can be various existing discharge methods. Specifically, for example, electrodeless discharge (such as radio frequency inductively coupled plasma (ICP), microwave discharge), single-electrode discharge (such as corona discharge, plasma jet formed by monopole discharge), double-electrode discharge (such as dielectric barrier discharge, bare electrode radio frequency glow discharge), and multi-electrode discharge (such as discharge using a floating electrode as the third electrode).

[0071] The specific embodiments of the invention also provide a vehicle plastic part, at least part of the surface of which has the above-mentioned surface hardening coating for vehicle plastic parts. In some specific embodiments, the above-mentioned surface hardening coating for vehicle plastic parts is deposited on part or all of the surface of the vehicle plastic part.

[0072] The following further illustrates the present invention through specific examples.

[0073] Example

[0074] Description of the test method

[0075] Coating thickness test: Coating on a silicon wafer and detecting with the American Filmetrics F20-UV - thin film thickness measuring instrument.

[0076] Transmittance test: Measuring with the American Perkin-Elmer-Lambda 950 type ultraviolet-visible spectrophotometer.

[0077] Color difference value test: It will be measured using a Konica Minolta spectrophotometer.

[0078] Hardness test:

[0079] It will be measured using a KLA nanoindentation instrument.

[0080] Adhesion test:

[0081] It will be tested according to the ASTM D3359 standard.

[0082] Example 1

[0083] After cleaning and drying the transparent PC (polycarbonate) plastic part and the black PC plastic part, place them on the bracket in the reaction chamber of the plasma coating equipment. Pump the background vacuum to 20 mT, introduce 200 sccm of argon gas. When the pressure stabilizes at 55 mT, turn on the chamber discharge, set the ICP power to 600 w, the duty cycle to 10%, the bias voltage to 300 V, and the treatment time to 10 min to clean and activate the substrate.

[0084] Mix octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane evenly according to a mass ratio of 10:1. Set two upper and lower feed ports with flow rates of 160 μl / min respectively. Introduce 65 sccm of oxygen and 50 sccm of argon gas, maintain the vacuum degree at 50 mT, turn on the discharge, set the ICP power to 700 W, load the bias voltage of 450 V, the duty cycle to 30%, and the coating time to 90 min to form a hardening coating.

[0085] After the coating is completed, the chamber returns to atmospheric pressure, take out the sample piece, and test the coating thickness, transmittance, hardness, and adhesion and list them in Table 1 below.

[0086] Example 2

[0087] After cleaning and drying the transparent PC (polycarbonate) plastic part and the black PC plastic part, place them on the bracket in the reaction chamber of the plasma coating equipment. Pump the background vacuum to 20 mT, introduce 200 sccm of argon gas. When the pressure stabilizes at 55 mT, turn on the chamber discharge, set the ICP power to 600 w, the duty cycle to 10%, the bias voltage to 300 V, and the treatment time to 10 min to clean and activate the substrate.

[0088] Mix octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane evenly according to a mass ratio of 10:1. Set two upper and lower feed ports with flow rates of 160 μl / min respectively. Introduce 65 sccm of oxygen and 50 sccm of argon gas, maintain the vacuum degree at 50 mT, turn on the discharge, set the ICP power to 400 W, load the bias voltage of 450 V, the duty cycle to 30%, and the coating time to 90 min to form a hardening coating.

[0089] After the coating is completed, the chamber is restored to atmospheric pressure, and the sample pieces are taken out for testing the coating thickness, transmittance, hardness, and adhesion, which are listed in Table 1 below.

[0090] Example 3

[0091] After cleaning and drying the transparent PC (polycarbonate) plastic parts and black PC plastic parts, place them on the bracket in the reaction chamber of the plasma coating equipment. Pump the background vacuum to 20 mT, introduce 200 sccm of argon gas. When the pressure stabilizes at 55 mT, turn on the chamber discharge, set the ICP power to 600 w, the duty cycle to 10%, the bias voltage to 300 V, and the treatment time to 10 min to clean and activate the substrate.

[0092] Mix octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane evenly according to the mass ratio of 10:1. Set the upper and lower feeding ports, with flow rates of 160 μl / min respectively. Introduce 65 sccm of oxygen and 50 sccm of argon gas, maintain the vacuum degree at 50 mT, turn on the discharge, set the ICP power to 200 W, apply the bias voltage of 450 V, the duty cycle to 30%, and the coating time to 90 min to form a hardening coating.

[0093] After the coating is completed, the chamber is restored to atmospheric pressure, and the sample pieces are taken out for testing the coating thickness, transmittance, hardness, and adhesion, which are listed in Table 1 below.

[0094] Example 4

[0095] After cleaning and drying the transparent PC (polycarbonate) plastic parts and black PC plastic parts, place them on the bracket in the reaction chamber of the plasma coating equipment. Pump the background vacuum to 20 mT, introduce 200 sccm of argon gas. When the pressure stabilizes at 55 mT, turn on the chamber discharge, set the ICP power to 600 w, the duty cycle to 10%, the bias voltage to 300 V, and the treatment time to 10 min to clean and activate the substrate.

[0096] Mix octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane evenly according to the mass ratio of 10:1. Set the upper and lower feeding ports, with flow rates of 160 μl / min respectively. Introduce 65 sccm of oxygen and 50 sccm of argon gas, maintain the vacuum degree at 50 mT, turn on the discharge, set the ICP power to 400 W, apply the bias voltage of 600 V, the duty cycle to 30%, and the coating time to 90 min to form a hardening coating.

[0097] After the coating is completed, the chamber is restored to atmospheric pressure, and the sample pieces are taken out for testing the thickness, transmittance, hardness, and adhesion of the coating, which are listed in Table 1 below.

[0098] Example 5

[0099] After cleaning and drying the transparent PC (polycarbonate) plastic parts and black PC plastic parts, place them on the bracket in the reaction chamber of the plasma coating equipment. Pump the background vacuum to 20 mT, introduce 200 sccm of argon gas. When the pressure stabilizes at 55 mT, turn on the chamber discharge, set the ICP power to 600 w, the duty cycle to 10%, the bias voltage to 300 V, and the treatment time to 10 min to clean and activate the substrate.

[0100] Mix octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane evenly according to the mass ratio of 10:1. Set two upper and lower feeding ports with flow rates of 160 μl / min respectively. Introduce 65 sccm of oxygen and 50 sccm of argon gas, maintain the vacuum degree at 50 mT, turn on the discharge, set the ICP power to 400 W, load the bias voltage of 200 V, the duty cycle to 30%, and the coating time to 90 min to form a hardening coating.

[0101] After the coating is completed, the chamber is restored to atmospheric pressure, and the sample pieces are taken out for testing the coating thickness, transmittance, hardness and adhesion and listed in Table 1 below.

[0102] Example 6

[0103] After cleaning and drying the transparent PC (polycarbonate) plastic parts and black PC plastic parts, place them on the bracket in the reaction chamber of the plasma coating equipment. Pump the background vacuum to 20 mT, introduce 200 sccm of argon gas. When the pressure stabilizes at 55 mT, turn on the chamber discharge, set the ICP power to 600 w, the duty cycle to 10%, the bias voltage to 300 V, and the treatment time to 10 min to clean and activate the substrate.

[0104] Mix octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane evenly according to the mass ratio of 10:1. Set two upper and lower feeding ports with flow rates of 160 μl / min respectively. Introduce 115 sccm of argon gas, maintain the vacuum degree at 50 mT, turn on the discharge, set the ICP power to 400 W, load the bias voltage of 450 V, the duty cycle to 30%, and the coating time to 90 min to form a hardening coating.

[0105] After the coating is completed, the chamber is restored to atmospheric pressure, and the sample pieces are taken out for testing the coating thickness, transmittance, hardness and adhesion and listed in Table 1 below.

[0106] Example 7

[0107] After cleaning and drying the transparent PC (polycarbonate) plastic parts and black PC plastic parts, place them on the bracket in the reaction chamber of the plasma coating equipment. Pump the background vacuum to 20 mT, introduce 200 sccm of argon gas. When the pressure stabilizes at 55 mT, turn on the chamber discharge, set the ICP power to 600 w, the duty cycle to 10%, the bias voltage to 300 V, and the treatment time to 10 min to clean and activate the substrate.

[0108] Octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane were mixed evenly at a mass ratio of 10:1. Two feeding ports were set up, with flow rates of 160 μl / min respectively. Oxygen was introduced at 115 sccm, the vacuum was maintained at 50 mT, the discharge was started, the ICP power was set at 400 W, the bias voltage was loaded at 450 V, the duty cycle was 30%, and the coating time was 90 min to form a hardening coating.

[0109] After the coating was completed, the chamber was restored to atmospheric pressure, and the sample pieces were taken out for testing of coating thickness, transmittance, hardness and adhesion, which are listed in Table 1 below.

[0110] Example 8

[0111] The transparent PC (polycarbonate) plastic parts and black PC plastic parts were cleaned and dried and then placed on the brackets in the reaction chamber of the plasma coating equipment. The background vacuum was pumped to 20 mT, and 200 sccm of argon was introduced. When the pressure was stabilized at 55 mT, the chamber discharge was started, the ICP power was set at 600 w, the duty cycle was 10%, the bias voltage was 300 V, and the treatment time was 10 min to clean and activate the substrate.

[0112] Octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane were mixed evenly at a mass ratio of 10:1. Two feeding ports were set up, with flow rates of 160 μl / min respectively. Oxygen was introduced at 65 sccm and argon at 50 sccm. The vacuum was maintained at 50 mT, the discharge was started, the ICP power was set at 400 W, the bias voltage was loaded at 450 V, the duty cycle was 10%, and the coating time was 90 min to form a hardening coating.

[0113] After the coating was completed, the chamber was restored to atmospheric pressure, and the sample pieces were taken out for testing of coating thickness, transmittance, hardness and adhesion, which are listed in Table 1 below.

[0114] Example 9

[0115] The transparent PC (polycarbonate) plastic parts and black PC plastic parts were cleaned and dried and then placed on the brackets in the reaction chamber of the plasma coating equipment. The background vacuum was pumped to 20 mT, and 200 sccm of argon was introduced. When the pressure was stabilized at 55 mT, the chamber discharge was started, the ICP power was set at 600 w, the duty cycle was 10%, the bias voltage was 300 V, and the treatment time was 10 min to clean and activate the substrate.

[0116] Mix tetraethyl orthosilicate and 3-aminopropyltrimethoxysilane evenly at a mass ratio of 5:1. Set two upper and lower feeding ports with flow rates of 160 μl / min respectively. Introduce 65 sccm of oxygen and 50 sccm of argon, maintain a vacuum degree of 50 mT, turn on the discharge, set the ICP power to 400 W, apply a bias voltage of 450 V, a duty cycle of 30%, and a coating time of 90 min to form a hardening coating.

[0117] After the coating is completed, the chamber is restored to normal pressure, and the sample pieces are taken out for testing the coating thickness, transmittance, hardness, and adhesion, which are listed in Table 1 below.

[0118] Example 10

[0119] Clean and dry the transparent PC (polycarbonate) plastic parts and black PC plastic parts, then place them on the bracket in the reaction chamber of the plasma coating equipment. Pump the background vacuum to 20 mT, introduce 200 sccm of argon. When the pressure stabilizes at 55 mT, turn on the chamber discharge, set the ICP power to 600 w, a duty cycle of 10%, a bias voltage of 300 V, and a treatment time of 10 min to clean and activate the substrate.

[0120] Mix octamethyltrisiloxane and 3-(2,3-epoxypropoxy)propyltrimethoxysilane evenly at a mass ratio of 1:1. Set two upper and lower feeding ports with flow rates of 160 μl / min respectively. Introduce 65 sccm of oxygen and 50 sccm of argon, maintain a vacuum degree of 50 mT, turn on the discharge, set the ICP power to 400 W, apply a bias voltage of 450 V, a duty cycle of 30%, and a coating time of 90 min to form a hardening coating.

[0121] After the coating is completed, the chamber is restored to normal pressure, and the sample pieces are taken out for testing the coating thickness, transmittance, hardness, and adhesion, which are listed in Table 1 below.

[0122] Example 11

[0123] Clean and dry the transparent PC (polycarbonate) plastic parts and black PC plastic parts, then place them on the bracket in the reaction chamber of the plasma coating equipment. Pump the background vacuum to 20 mT, introduce 200 sccm of argon. When the pressure stabilizes at 55 mT, turn on the chamber discharge, set the ICP power to 600 w, a duty cycle of 10%, a bias voltage of 300 V, and a treatment time of 10 min to clean and activate the substrate.

[0124] Octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane were mixed evenly at a mass ratio of 10:1. Two feeding ports, upper and lower, were set, with flow rates of 160 μl / min respectively. Oxygen was introduced at 65 sccm and argon at 50 sccm. The vacuum degree was maintained at 50 mT. Discharge was initiated, setting the ICP power at 1000 W, applying a bias voltage of 450 V, with a duty cycle of 30%, and a coating time of 90 min to form a hardening coating.

[0125] After the coating was completed, the chamber was restored to atmospheric pressure, and the sample pieces were taken out for testing of coating thickness, transmittance, hardness, and adhesion, which are listed in Table 1 below.

[0126] Example 12

[0127] The transparent PC (polycarbonate) plastic parts and black PC plastic parts were cleaned and dried and then placed on the brackets in the reaction chamber of the plasma coating equipment. The background vacuum was pumped down to 20 mT, and 200 sccm of argon was introduced. When the pressure stabilized at 55 mT, the chamber discharge was initiated, setting the ICP power at 600 w, the duty cycle at 10%, the bias voltage at 300 V, and the treatment time at 10 min to clean and activate the substrate.

[0128] Octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane were mixed evenly at a mass ratio of 10:1. Two feeding ports, upper and lower, were set, with flow rates of 160 μl / min respectively. Oxygen was introduced at 65 sccm and argon at 50 sccm. The vacuum degree was maintained at 50 mT. Discharge was initiated, setting the ICP power at 400 W, applying a bias voltage of 450 V, with a duty cycle of 40%, and a coating time of 90 min to form a hardening coating.

[0129] After the coating was completed, the chamber was restored to atmospheric pressure, and the sample pieces were taken out for testing of coating thickness, transmittance, hardness, and adhesion, which are listed in Table 1 below.

[0130] Comparative Example 1

[0131] Blank samples of transparent PC plastic parts and black PC plastic parts without coating were subjected to transmittance testing, which are listed in Table 1 below.

[0132] Comparative Example 2

[0133] The transparent PC (polycarbonate) plastic parts and black PC plastic parts were cleaned and dried and then placed on the brackets in the reaction chamber of the plasma coating equipment. Octamethylcyclotetrasiloxane was set with two feeding ports, upper and lower, with flow rates of 160 μl / min respectively. Oxygen was introduced at 65 sccm and argon at 50 sccm. The vacuum degree was maintained at 50 mT. Discharge was initiated, setting the ICP power at 700 W, applying a bias voltage of 450 V, with a duty cycle of 30%, and a coating time of 90 min to form a hardening coating.

[0134] After the coating is completed, the chamber is restored to atmospheric pressure, and the sample pieces are taken out for testing the coating thickness, transmittance, hardness, and adhesion, which are listed in Table 1 below.

[0135] Comparative Example 3

[0136] After cleaning and drying the transparent PC (polycarbonate) plastic parts and black PC plastic parts, place them on the bracket in the reaction chamber of the plasma coating equipment. Pump the background vacuum to 20 mT, introduce 200 sccm of argon gas. When the pressure stabilizes at 55 mT, turn on the chamber discharge, set the ICP power to 600 w, the duty cycle to 10%, the bias voltage to 300 V, and the processing time to 10 min to clean and activate the substrate.

[0137] Mix octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane evenly according to the mass ratio of 10:1. Set the upper and lower feeding ports with flow rates of 160 μl / min respectively. Introduce 65 sccm of oxygen and 50 sccm of argon gas. Maintain the vacuum degree at 50 mT. Turn on the discharge, set the ICP power to 400 W, do not apply the bias voltage, and the duty cycle to 30%. The coating time is 90 min to form a hardening coating.

[0138] After the coating is completed, the chamber is restored to atmospheric pressure, and the sample pieces are taken out for testing the coating thickness, transmittance, hardness, and adhesion, which are listed in Table 1 below.

[0139] Comparative Example 4

[0140] After cleaning and drying the transparent PC (polycarbonate) plastic parts and black PC plastic parts, place them on the bracket in the reaction chamber of the plasma coating equipment. Pump the background vacuum to 20 mT, introduce 200 sccm of argon gas. When the pressure stabilizes at 55 mT, turn on the chamber discharge, set the ICP power to 600 w, the duty cycle to 10%, the bias voltage to 300 V, and the processing time to 10 min to clean and activate the substrate.

[0141] For octamethylcyclotetrasiloxane, set the upper and lower feeding ports with flow rates of 160 μl / min respectively. Introduce 65 sccm of oxygen and 50 sccm of argon gas. Maintain the vacuum degree at 50 mT. Turn on the discharge, set the ICP power to 400 W, apply the bias voltage of 450 V, and the duty cycle to 30%. The coating time is 90 min to form a hardening coating.

[0142] After the coating is completed, the chamber is restored to atmospheric pressure, and the sample pieces are taken out for testing the coating thickness, transmittance, hardness, and adhesion, which are listed in Table 1 below.

[0143] Comparative Example 5

[0144] After cleaning and drying the transparent PC (polycarbonate) plastic part and the black PC plastic part, place them on the bracket in the reaction chamber of the plasma coating equipment. Pump the background vacuum to 20 mT, introduce 200 sccm of argon gas. When the pressure stabilizes at 55 mT, turn on the chamber discharge, set the ICP power to 600 W, the duty cycle to 10%, the bias voltage to 300 V, and the treatment time to 10 min to clean and activate the substrate.

[0145] Set up two upper and lower feed ports, the flow rate of γ-methacryloxypropyltrimethoxysilane is 160 μl / min, introduce 65 sccm of oxygen and 50 sccm of argon gas, maintain the vacuum degree at 50 mT, turn on the discharge, set the ICP power to 400 W, load the bias voltage of 450 V, the duty cycle to 30%, and the coating time to 90 min to form a hardening coating.

[0146] After the coating is completed, the chamber is restored to normal pressure, and the sample pieces are taken out for testing the coating thickness, transmittance, hardness and adhesion, which are listed in Table 1 below.

[0147] Table 1 Test results of Examples 1-12 and Comparative Examples 1-5

[0148]

[0149] According to the results in Table 1 above, using organosilicon with short saturated carbon chains and organosilicon with epoxy groups, unsaturated carbon-carbon bonds or amino groups as monomers as raw materials, and plasma excitation, the coating with excellent hardness, color difference and adhesion can be prepared by adjusting the power, duty cycle and bias voltage of plasma discharge. Among them, in Comparative Example 4, when only octamethylcyclotetrasiloxane was used, although it had good hardness, the adhesion was relatively poor. In Comparative Example 5, when only γ-methacryloxypropyltrimethoxysilane was used, although it had good adhesion, the hardness was relatively poor and the color difference became larger. In Comparative Example 3, although octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane were used simultaneously, due to the lack of loading of the bias voltage, both the hardness and adhesion were not good, and the color difference was very large. However, as in Example 4, the bias voltage should not be too large, otherwise the adhesion will decrease. According to Examples 3 and 11, if the power is too low, less than 200 W, both the adhesion and hardness will become poor and the color difference will become larger. If the power is too high, exceeding 1000 W, the color difference will become larger.

[0150] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A surface hardening coating for vehicle plastic parts, characterized in that, The coating is formed by depositing plasma of at least one of the structures shown by the following formula (1), formula (2) or formula (3) and a silicone monomer of the structure shown by the following formula (4) on the surface of a vehicle plastic part substrate. In formula (1), R1 is a hydrogen atom, an alkyl group with 1 - 4 carbon atoms, an alkoxy group with 1 - 4 carbon atoms or an alkanoyloxy group with 1 - 4 carbon atoms; R2 is an alkyl group with 1 - 4 carbon atoms, an alkoxy group with 1 - 4 carbon atoms or an alkanoyloxy group with 1 - 4 carbon atoms; n is an integer from 3 to 10. In formula (2), R3, R4 and R5 are each independently selected from a hydrogen atom, an alkyl group with 1 - 4 carbon atoms, an alkoxy group with 1 - 4 carbon atoms or an alkanoyloxy group with 1 - 4 carbon atoms; R6 is an alkyl group with 1 - 4 carbon atoms, an alkoxy group with 1 - 4 carbon atoms or an alkanoyloxy group with 1 - 4 carbon atoms. In formula (3), R7, R8 and R9 are each independently selected from a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or an alkanoyloxy group having 1 to 4 carbon atoms, and R 10 is an alkyl group having 1 to 4 carbon atoms or an acyl group having 1 to 4 carbon atoms, and m is an integer from 2 to 100; In formula (4), R 11 , R 12 and R 13 are each independently selected from a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, R 14 is an organic group having a carbon-carbon double bond, a carbon-carbon triple bond, an epoxy group, or an amino group, and L is a linking moiety; The hardness of the coating is tested by a KLA nanoindentation instrument to be above 1.5 GPa, and the adhesion of the coating is tested according to the ASTM D3359 standard to be above 3B.

2. The coating according to claim 1, wherein, The hardness of the coating is tested by a KLA nanoindentation instrument to be above 2.8 GPa, and the adhesion of the coating is tested according to the ASTM D3359 standard to be above 5B.

3. The coating according to claim 1, characterized in that, The R1 is methyl or ethyl, and the R2 is methyl or ethyl.

4. The coating according to claim 1, wherein The silicone of the structure shown by formula (1) is at least one of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, 1,3,5,7 - tetramethylcyclotetrasiloxane, decamethylcyclopentasiloxane or dodecamethylcyclohexasiloxane.

5. The coating according to claim 1, characterized in that, The silicone of the structure shown by formula (2) is dimethylsiloxane, tetraethoxysilane, tetramethoxysilane, tetrabutyl orthosilicate, tetramethyl orthosilicate, tetraethyl orthosilicate, tetra - isopropyl orthosilicate, methyltripropoxysilane, triethoxysilane, methyltriethoxysilane, dimethoxydimethylsilane, di - tert - butoxydimethoxysilane.

6. The coating according to claim 1, wherein The silicone of the structure shown by formula (3) is at least one of 1,1,3,3 - tetramethyl - 1,3 - disiloxane, bis(trimethylsilyloxy)methylsilane, decamethyltetrasiloxane, octamethyltrisiloxane, hexamethyldisiloxane, tetramethyldisiloxane, hexaethyldisiloxane, 3H,5H - octamethyltetrasiloxane.

7. The coating according to claim 1, wherein The silicone of the structure shown by formula (4) has the structure shown by the following formula (5). In formula (5), R 15 is an alkylene group having 1 to 4 carbon atoms, R 16 is a group of formula (6), (7), (8), (9), vinyl or amino, In formula (9), R 17 , R 18 and R 19 are each independently selected from a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

8. The coating according to claim 7, wherein The R 17 and R 18 are hydrogen atoms, and the R 19 is a hydrogen atom or a methyl group.

9. The coating according to claim 1, wherein The silicone with the structure shown in formula (4) is at least one of 3-(methacryloyloxy)propyltrimethoxysilane, γ-methacryloyloxypropyltriisopropoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, γ-methacryloyloxypropyltris(trimethylsiloxy)silane, 3-methacryloyloxypropyltriethoxysilane, 3-(methacryloyloxy)propylmethyldiethoxysilane, 3-(acryloyloxy)propyltrimethoxysilane, 3-(acryloyloxy)methyldimethoxysilane, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane, γ-glycidyletheroxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltriethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, 3-(2,3-epoxypropoxy)propylmethyldiethoxysilane, allyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris(2-methoxyethoxy)-silane, vinyltriisopropoxysilane, methylvinyldimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, diethylenetriaminepropyltrimethoxysil, 3-aminopropylmethyldimethoxysilane.

10. The coating according to claim 1, characterized in that, The thickness of the coating is 1500 - 3500 nm.

11. The coating according to claim 1, characterized in that, The automotive plastic part is a door panel, dashboard, bumper, exhaust manifold, lamp housing or interior part.

12. A method for preparing a surface hardening coating for a vehicle plastic part as described in any one of claims 1-11, characterized in that, It includes the following steps: Provide a substrate of an automotive plastic part, and place the substrate of the automotive plastic part in a plasma deposition chamber provided with a bias voltage; Introduce the vapor of at least one of the structures shown in formula (1), formula (2) or formula (3) and the silicone monomer with the structure shown in formula (4) into the reaction chamber, introduce at least one of oxygen or inert gas, maintain the pressure in the reaction chamber not greater than 100 mT, turn on the pulsed plasma discharge and the bias voltage, and deposit the coating by adjusting the power, duty cycle of the pulsed plasma discharge and the bias voltage.

13. According to the preparation method of claim 12, characterized in that, The power of the pulsed plasma discharge is 200 W - 1000 W, the duty cycle is 5 - 50%, and the bias voltage is 200 V - 1000 V.

14. The preparation method according to claim 13, characterized in that, The power of the pulsed plasma discharge is 400 W - 700 W, the duty cycle is 30 - 40%, and the bias voltage is 450 V - 600 V.

15. An automotive plastic part with at least a part of its surface having the surface hardening coating for automotive plastic parts described in any one of claims 1 - 11.

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