Automotive plastic part surface hardening coating and preparation method therefor

Abstract

An automotive plastic part surface hardening coating and a preparation method therefor. The coating can be prepared by means of plasma excitation from organic silicon having a short saturated carbon chain and an organic silicon monomer having an epoxy group, an unsaturated carbon-carbon bond or an amino group as raw materials. The coating having excellent hardness and adhesion can be prepared by adjusting the power, the duty ratio and the bias voltage of plasma discharge.

Description

A surface hardening coating for automotive plastic parts and preparation method thereof

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 28, 2023, with application number 202311856113.7 and invention name “A hardening coating on the surface of automotive plastic parts and its preparation method”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention belongs to the field of surface hardening of plastic substrates used in the automotive field, and particularly relates to a surface hardening coating for automotive plastic parts and a preparation method thereof. Background Art

[0003] The continuous advancement of automotive technology is driving higher demands on vehicle safety, lightweighting, and appearance. Plastics, due to their excellent optical properties, aging resistance, and ease of molding, are increasingly being used in automotive applications such as door panels, instrument panels, bumpers, exhaust manifolds, lampshades, and interior trim. However, most plastic products have a low hardness and are easily scratched during production and use. Therefore, protective treatments to harden the plastic substrate surface are essential.

[0004] Currently, photocuring is an effective method for hardening plastic surfaces. CN111218020A discloses a method for preparing a hardened material. Polyurethane acrylic resin oligomers and polymers of varying functionality are added to an ester solvent, stirred for reaction, and then a UV initiator is added. Continued stirring produces a hardened coating. This coating not only requires the use of organic solvents but also suffers from surface issues such as leveling when applied to substrates by spray or flow coating.

[0005] Plasma-enhanced chemical vapor deposition (PECVD) is a new technology that uses plasma excitation to generate reactions at low temperatures. Using PECVD to deposit hardening films on plastic surfaces not only achieves uniform and efficient deposition, but also creates a dense structure. It requires no solvents and is environmentally friendly, offering broad application prospects.

[0006] Summary of the Invention

[0007] The specific embodiment of the present invention uses silicone as raw material and forms a coating with excellent hardness and adhesion on the surface of automotive plastic parts through a plasma process. The specific scheme is as follows:

[0008] A hardening coating on the surface of a plastic part for an automobile is formed by depositing a plasma of at least one of the structures represented by the following formula (1), formula (2), or formula (3) and an organosilicon monomer represented by the following formula (4) on the surface of a substrate of the plastic part for an automobile.

[0009] In formula (1), R1 is a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group or a C1-C4 acyloxy group, R2 is a C1-C4 alkyl group, a C1-C4 alkoxy group or a C1-C4 alkanoyloxy group, and n is an integer from 3 to 10;

[0010] In formula (2), R3, R4 and R5 are independently selected from hydrogen atom, C1-C4 alkyl, C1-C4 alkoxy or C1-C4 alkanoyloxy, and R6 is C1-C4 alkyl, C1-C4 alkoxy or C1-C4 alkanoyloxy;

[0011] In formula (3), R7, R8 and R9 are independently selected from hydrogen atom, C1-C4 alkyl, C1-C4 alkoxy or C1-C4 alkanoyloxy, R 10 is a C1-C4 alkyl group or a C1-C4 acyl group, and m is an integer from 2 to 100;

[0012] In formula (4), R 11 、R 12 and R 13 are independently selected from hydrogen atom, C1-C4 alkyl or C1-C4 alkoxy, 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 part;

[0013] The hardness of the coating is above 1.5 GPa when tested by a KLA nanoindenter, and the adhesion of the coating is above 3B when tested according to ASTM D3359 standard.

[0014] Optionally, the hardness of the coating is greater than 2.8 GPa when tested using a KLA nanoindenter, and the adhesion of the coating is greater than 5B when tested according to ASTM D3359 standard.

[0015] Optionally, R1 is methyl or ethyl, and R2 is methyl or ethyl.

[0016] Optionally, the organosilicon with the structure represented by formula (1) is at least one of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, decamethylcyclopentasiloxane or dodecamethylcyclohexasiloxane.

[0017] Optionally, the organosilicon of the structure shown in formula (2) is dimethylsiloxane, tetraethoxysilane, tetramethoxysilane, tetrabutyl silicate, tetramethyl orthosilicate, tetraethyl orthosilicate, tetraisopropyl orthosilicate, methyltripropoxysilane, triethoxysilane, methyltriethoxysilane, dimethoxydimethylsilane, di-tert-butoxydimethoxysilane,

[0018] Optionally, the organosilicon with the structure represented by formula (3) is at least one of 1,1,3,3-tetramethyl-1,3-disiloxane, bistrimethylsiloxymethylsilane, decamethyltetrasiloxane, octamethyltrisiloxane, hexamethyldisiloxane, tetramethyldisiloxane, hexaethyldisiloxane, and 3H,5H-octamethyltetrasiloxane.

[0019] Optionally, the organic silicon having the structure shown in formula (4) has the structure shown in formula (5) below,

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

[0021] In formula (9), R 17 、R 18 and R 19 Each is independently selected from a hydrogen atom or a C1-C4 alkyl group.

[0022] Optionally, the R 17 and R 18 is a hydrogen atom, the R 19 is a hydrogen atom or a methyl group.

[0023] Optionally, the organic silicon of the structure shown in formula (4) is 3-(methacryloyloxy)propyltrimethoxysilane, γ-methacryloyloxypropyltriisopropoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, γ-methacryloyloxypropyltri(trimethylsiloxy)silane, 3-methacryloyloxypropyltriethoxysilane, 3-(methacryloyloxy)propylmethyldiethoxysilane, 3-(acryloyloxy)propyltrimethoxysilane, 3-(acryloyloxy)methyldimethoxysilane, 3-(2,3-epoxypropyloxy)propyltrimethoxysilane, 3-(2,3-epoxypropyloxy)propylmethyldimethoxysilane. At least one of alkyl, γ-glycidyloxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltriethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, 3-(2,3-epoxypropyloxy)propylmethyldiethoxysilane, allyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri-(2-methoxyethoxy)-silane, vinyltriisopropoxysilane, methylvinyldimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, diethylenetriaminopropyltrimethoxysilane, and 3-aminopropylmethyldimethoxysilane.

[0024] Optionally, the coating has a thickness of 1500 to 3500 nm.

[0025] Optionally, the automotive plastic part is a door panel, an instrument panel, a bumper, an exhaust manifold, a lampshade or an interior trim part.

[0026] A method for preparing the surface hardening coating of a vehicle plastic part as described above comprises the following steps:

[0027] Providing a vehicle plastic substrate, and placing the vehicle plastic substrate in a plasma deposition chamber provided with a bias voltage;

[0028] The vapor of at least one of the structures represented by formula (1), formula (2) or formula (3) and the organic silicon monomer represented by formula (4) is introduced into a reaction chamber, and at least one of oxygen or inert gas is introduced, the pressure of the reaction chamber is maintained at no more than 100 mT, pulse plasma discharge and bias voltage are started, and the coating is deposited by adjusting the power, duty cycle and bias voltage of the pulse plasma discharge.

[0029] Optionally, the power of the pulse plasma discharge is 200W to 1000W, the duty cycle is 5 to 50%, and the bias voltage is 200V to 1000V.

[0030] Optionally, the power of the pulse plasma discharge is 400W to 700W, the duty cycle is 30% to 40%, and the bias voltage is 450V to 600V.

[0031] A vehicle plastic part, at least part of whose surface is provided with the above-mentioned surface hardening coating.

[0032] The hardening coating on the surface of automotive plastic parts according to a specific embodiment of the present invention is formed by plasma deposition on the surface of the automotive plastic part substrate using short saturated carbon chain silicone and silicone with epoxy groups, unsaturated carbon-carbon bonds or amino groups as monomers. During the preparation process, the coating can be made to have excellent hardness and adhesion by adjusting the power, duty cycle and bias voltage of the plasma discharge. DETAILED DESCRIPTION

[0033] A specific embodiment of the present invention provides a hardening coating on the surface of a plastic part for automobiles, wherein the coating is formed by plasma deposition of at least one of the structures represented by the following formula (1), formula (2), or formula (3) and an organosilicon monomer represented by the following formula (4) on the surface of a substrate of the plastic part for automobiles.

[0034] In formula (1), R1 is a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group or a C1-C4 alkanoyloxy group, R2 is a C1-C4 alkyl group, a C1-C4 alkoxy group or a C1-C4 alkanoyloxy group, and n is an integer from 3 to 10;

[0035] In formula (2), R3, R4 and R5 are independently selected from hydrogen atom, C1-C4 alkyl, C1-C4 alkoxy or C1-C4 alkanoyloxy, and R6 is C1-C4 alkyl, C1-C4 alkoxy or C1-C4 alkanoyloxy;

[0036] In formula (3), R7, R8 and R9 are independently selected from hydrogen atom, C1-C4 alkyl, C1-C4 alkoxy or C1-C4 alkanoyloxy, R 10 is a C1-C4 alkyl group or a C1-C4 acyl group, m is an integer from 2 to 100, and in some specific embodiments, m is an integer from 2 to 10;

[0037] In formula (4), R 11 、R 12 and R 13 are independently selected from hydrogen atom, C1-C4 alkyl or C1-C4 alkoxy, 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 part;

[0038] The hardness of the coating is above 1.5 GPa when tested by a KLA nanoindenter, and the adhesion of the coating is above 3B when tested according to ASTM D3359 standard.

[0039] In some specific embodiments of the present invention, the surface hardening coating of automotive plastic parts has a hardness of more than 2.0 GPa, and further more than 2.8 GPa, as tested by a KLA nanoindenter, and an adhesion of more than 4B, and further more than 5B, as tested according to the ASTM D3359 standard.

[0040] In some specific embodiments of the surface hardening coating for automotive plastic parts of the present invention, the C1-C4 alkyl group may be, for example, a methyl group, an ethyl group, a propyl group or a butyl group; the C1-C4 alkoxy group may be, for example, a methoxy group, an ethoxy group, a propoxy group or a butoxy group; and the C1-C4 alkanoyloxy group may be, for example, a formyloxy group, an acetoxy group, a propionyloxy group or a butyryloxy group.

[0041] In the specific embodiments of the present invention, the surface hardening coating for automotive plastic parts, in some specific embodiments, the C1-C4 alkyl group is methyl, isopropyl or isobutyl, the C1-C4 alkoxy group is methoxy, isopropoxy or isobutoxy, and the C1-C4 alkanoyloxy group is formyloxy, isopropyloxy or isobutyloxy.

[0042] In the specific embodiments of the present invention, the surface hardening coating of automotive plastic parts, in some specific embodiments, the organosilicon with the structure represented by formula (1) is at least one of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, 1,3,5,7,-tetramethylcyclotetrasiloxane, decamethylcyclopentasiloxane or dodecamethylcyclohexasiloxane.

[0043] In some embodiments of the present invention, the surface hardening coating of the automotive plastic parts is selected from dimethylsiloxane, tetraethoxysilane, tetramethoxysilane, tetrabutyl silicate, tetramethyl orthosilicate, tetraethyl orthosilicate, tetraisopropyl orthosilicate, methyltripropoxysilane, triethoxysilane, methyltriethoxysilane, dimethoxydimethylsilane, di-tert-butoxydimethoxysilane, and the like.

[0044] In the specific embodiments of the present invention, the surface hardening coating of automotive plastic parts, in some specific embodiments, the organosilicon with the structure represented by formula (3) is at least one of 1,1,3,3-tetramethyl-1,3-disiloxane, bistrimethylsiloxymethylsilane, decamethyltetrasiloxane, octamethyltrisiloxane, hexamethyldisiloxane, tetramethyldisiloxane, hexaethyldisiloxane, and 3H,5H-octamethyltetrasiloxane.

[0045] In some embodiments of the present invention, the surface hardening coating for automotive plastic parts has a structure represented by the following formula (5):

[0046] In formula (5), R 15 is a C1-C4 alkylene group, R 16 is a group of the following formula (6), (7), (8), or (9), a vinyl group, or an amino group,

[0047] In formula (9), R 17 、R 18 and R 19 Each is independently selected from a hydrogen atom or a C1-C4 alkyl group.

[0048] In some embodiments of the present invention, the surface hardening coating of the automotive plastic part is 17 and R 18 is a hydrogen atom, the R 19 is a hydrogen atom or a methyl group.

[0049] In the specific embodiment of the present invention, the surface hardening coating of the automotive plastic parts, in some specific embodiments, the organic silicon of the structure shown in formula (4) is 3-(methacryloyloxy)propyltrimethoxysilane, γ-methacryloyloxypropyltriisopropoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, γ-methacryloyloxypropyltri(trimethylsiloxy)silane, 3-methacryloyloxypropyltriethoxysilane, 3-(methacryloyloxy)propylmethyldiethoxysilane, 3-(acryloyloxy)propyltrimethoxysilane, 3-(acryloyloxy)methyldimethoxysilane, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-(2,3 -glycidoxy)propylmethyldimethoxysilane, γ-glycidoxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltriethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, 3-(2,3-epoxypropyloxy)propylmethyldiethoxysilane, allyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri-(2-methoxyethoxy)-silane, vinyltriisopropoxysilane, methylvinyldimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, diethylenetriaminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane.

[0050] In the specific embodiments of the present invention, the surface hardening coating of the plastic parts for vehicle use, in some specific embodiments, the mass ratio of the organosilicon with the structures represented by formula (1), formula (2) and formula (3) to the organosilicon with the structure represented by formula (4) is 1:10 to 10:1. In some specific embodiments, the mass ratio of the organosilicon with the structures represented by formula (1), formula (2) and formula (3) to the organosilicon with the structure represented by 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.

[0051] In some embodiments of the present invention, the surface hardening coating for automotive plastic parts has a thickness of 1500 to 3500 nm, and 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.

[0052] In some embodiments of the present invention, the surface hardening coating of the automotive plastic part is a door panel, an instrument panel, a bumper, an exhaust manifold, a lampshade or an interior trim part.

[0053] A specific embodiment of the present invention further provides a method for preparing the above-mentioned surface hardening coating of a plastic part for a vehicle, comprising the following steps:

[0054] Providing a vehicle plastic substrate, and placing the vehicle plastic substrate in a plasma deposition chamber provided with a bias voltage;

[0055] The vapor of at least one of the structures represented by formula (1), formula (2) or formula (3) and the organic silicon monomer represented by formula (4) is introduced into a reaction chamber, and at least one of oxygen or inert gas is introduced, the pressure of the reaction chamber is maintained at no more than 100 mT, pulse plasma discharge and bias voltage are started, and the coating is deposited by adjusting the power, duty cycle and bias voltage of the pulse plasma discharge.

[0056] The method for preparing a surface hardening coating for automotive plastic parts of the present invention comprises the following steps: using a short saturated carbon chain organosilicon in a structure represented by formula (1), formula (2) or formula (3) and an organosilicon having an epoxy group, an unsaturated carbon-carbon bond or an amino group in a structure represented by formula (4) as raw materials, introducing at least one of oxygen or an inert gas, particularly when oxygen is introduced, starting pulse plasma discharge and bias voltage, and adjusting the power, duty cycle and bias voltage of the pulse plasma discharge to deposit and form a coating having a hardness of 1.5 GPa or more, further 2.0 GPa or more, further 2.8 GPa or more, and an adhesion of 3B or more, further 4B or more, and further 5B or more.

[0057] In the method for preparing a surface hardening coating on automotive plastic parts of the present invention, in some specific embodiments, the power of the pulsed plasma discharge is 200W to 1000W, the duty cycle is 5 to 50%, and the bias voltage is 200V to 1000V. In some specific embodiments, the power of the pulsed plasma discharge is 400W to 700W, specifically for example, 400W, 500W, 600W or 700W, etc., the duty cycle is 30 to 40%, specifically for example, 30%, 35% or 40%, etc., and the bias voltage is 450V to 600V, specifically for example, 450V, 500V, 550V or 600V, etc.

[0058] In the method for preparing a surface hardening coating for automotive plastic parts of the present invention, in some specific embodiments, the organic silicon monomers having the structures represented by formula (1) and formula (2) are mixed and introduced into a reaction chamber at a flow rate of 5 to 3000 ul / min, further 50 to 500 μl / min, specifically 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.

[0059] In the method for preparing a surface hardening coating on a plastic part for a vehicle of the present invention, in some specific embodiments, the amount of oxygen introduced is 50 to 500 sccm, and specific examples include 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 amount of inert gas introduced is 0 to 500 sccm, and specific examples include 50 sccm, 100 sccm, 150 sccm, 200 sccm, 250 sccm, 300 sccm, 350 sccm, 400 sccm, 450 sccm or 500 sccm, etc.

[0060] In some embodiments of the method for preparing a hardening coating on the surface of a plastic part for a vehicle of the present invention, only oxygen is introduced without introducing other inert gases, which is beneficial for further improving the hardness of the coating. In some embodiments, only inert gases are introduced. In some embodiments, oxygen and inert gases are introduced simultaneously.

[0061] In some specific embodiments of the method for preparing the surface hardening coating of a plastic part for a vehicle of the present invention, the inert gas is nitrogen, argon, helium, or the like.

[0062] In the method for preparing a hardening coating on the surface of a plastic part for a vehicle of the present invention, in some specific embodiments, the temperature in the reaction chamber is controlled at 20°C to 80°C, specifically, for example, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, or 80°C; the monomer vaporization temperature is 50°C to 180°C, specifically, for example, 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, and vaporization occurs under vacuum conditions.

[0063] In the method for preparing a surface hardening coating for automotive plastic parts according to a specific embodiment of the invention, in some specific embodiments, the pulse plasma discharge time is 1000s to 36000s, for example, it can be 1000s, 2000s, 3000s, 4000s, 5000s, 6000s, 7000s, 8000s, 9000s, 10000s, 15000s, 20000s, 25000s, 30000s, 36000s, etc.

[0064] In the method for preparing a surface hardening coating for automotive plastic parts according to a specific embodiment of the present invention, in some specific embodiments, in order to further improve the bonding strength of the silicone hydrophobic film layer, in some specific embodiments, the substrate is pretreated with continuous plasma before coating. The specific pretreatment method is, for example, evacuating to 10-200 mTorr and introducing one or more mixed gases of nitrogen, argon, helium or oxygen, starting plasma discharge to pretreat the substrate, or using heat, oxygen or high-energy radiation, etc.

[0065] In the method for preparing a hardening coating on the surface of automotive plastic parts according to a specific embodiment of the present invention, in some specific embodiments, the plasma discharge mode can be various existing discharge modes, for example, electrodeless discharge (such as radio frequency inductively coupled discharge (ICP), microwave discharge), single-electrode discharge (such as corona discharge, plasma jet formed by monopole discharge), dual-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).

[0066] A specific embodiment of the present invention further provides a vehicle plastic part, at least part of the surface of which has the above-mentioned vehicle plastic part surface hardening coating. In some specific embodiments, the above-mentioned vehicle plastic part surface hardening coating is deposited on part or all of the surface of the vehicle plastic part.

[0067] The present invention is further described below with reference to specific examples.

[0068] Example

[0069] Test method description

[0070] Coating thickness test: The coating was applied to the silicon wafer and tested using the American Filmetrics F20-UV-film thickness gauge.

[0071] Transmittance test: The measurement was performed using a US Perkin-Elmer-Lambda 950 UV-visible spectrophotometer.

[0072] Color difference test: Konicaminolta spectrophotometer will be used for measurement.

[0073] Hardness test:

[0074] The measurements were performed using a KLA nanoindenter.

[0075] Adhesion test:

[0076] Tested using ASTM D3359.

[0077] Example 1

[0078] After cleaning and drying, transparent PC (polycarbonate) plastic parts and black PC plastic parts are placed on the bracket of the reaction chamber of the plasma coating equipment. The back vacuum is pumped to 20mT, and 200sccm of argon gas is introduced. When the pressure stabilizes at 55mT, the chamber discharge is turned on, and the ICP power is set to 600w, the duty cycle is 10%, the bias voltage is 300V, and the processing time is 10min to clean and activate the substrate.

[0079] Octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane were mixed evenly in a mass ratio of 10:1, and two upper and lower feed ports were set with flow rates of 160 μl / min respectively. 65 sccm of oxygen and 50 sccm of argon were introduced, and the vacuum degree was maintained at 50 mT. The discharge was turned on and the ICP power was set to 700 W. The bias voltage was loaded to 450 V, the duty cycle was 30%, and the coating time was 90 min to form a hardened coating.

[0080] After the coating was completed, the chamber was restored to normal pressure, and the samples were taken out for coating thickness, transmittance, hardness and adhesion tests, which are listed in Table 1 below.

[0081] Example 2

[0082] After cleaning and drying, transparent PC (polycarbonate) plastic parts and black PC plastic parts are placed on the bracket of the reaction chamber of the plasma coating equipment. The back vacuum is pumped to 20mT, and 200sccm of argon gas is introduced. When the pressure stabilizes at 55mT, the chamber discharge is turned on, and the ICP power is set to 600w, the duty cycle is 10%, the bias voltage is 300V, and the processing time is 10min to clean and activate the substrate.

[0083] Octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane were mixed evenly in a mass ratio of 10:1, and two upper and lower feed ports were set with flow rates of 160 μl / min respectively. 65 sccm of oxygen and 50 sccm of argon were introduced, and the vacuum degree was maintained at 50 mT. The discharge was turned on and the ICP power was set to 400 W. The bias voltage was loaded to 450 V, the duty cycle was 30%, and the coating time was 90 min to form a hardened coating.

[0084] After the coating was completed, the chamber was restored to normal pressure, and the samples were taken out for coating thickness, transmittance, hardness and adhesion tests, which are listed in Table 1 below.

[0085] Example 3

[0086] After cleaning and drying, transparent PC (polycarbonate) plastic parts and black PC plastic parts are placed on the bracket of the reaction chamber of the plasma coating equipment. The back vacuum is pumped to 20mT, and 200sccm of argon gas is introduced. When the pressure stabilizes at 55mT, the chamber discharge is turned on, and the ICP power is set to 600w, the duty cycle is 10%, the bias voltage is 300V, and the processing time is 10min to clean and activate the substrate.

[0087] Octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane were mixed evenly in a mass ratio of 10:1, and two upper and lower feed ports were set with flow rates of 160 μl / min respectively. 65 sccm of oxygen and 50 sccm of argon were introduced, and the vacuum degree was maintained at 50 mT. The discharge was turned on and the ICP power was set to 200 W. The bias voltage was loaded to 450 V, the duty cycle was 30%, and the coating time was 90 min to form a hardened coating.

[0088] After the coating was completed, the chamber was restored to normal pressure, and the samples were taken out for coating thickness, transmittance, hardness and adhesion tests, which are listed in Table 1 below.

[0089] Example 4

[0090] After cleaning and drying, transparent PC (polycarbonate) plastic parts and black PC plastic parts are placed on the bracket of the reaction chamber of the plasma coating equipment. The back vacuum is pumped to 20mT, and 200sccm of argon gas is introduced. When the pressure stabilizes at 55mT, the chamber discharge is turned on, and the ICP power is set to 600w, the duty cycle is 10%, the bias voltage is 300V, and the processing time is 10min to clean and activate the substrate.

[0091] Octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane were mixed evenly in a mass ratio of 10:1, and two upper and lower feed ports were set with flow rates of 160 μl / min respectively. 65 sccm of oxygen and 50 sccm of argon were introduced, and the vacuum degree was maintained at 50 mT. The discharge was turned on and the ICP power was set to 400 W. The bias voltage was loaded to 600 V, the duty cycle was 30%, and the coating time was 90 min to form a hardened coating.

[0092] After coating, the chamber was restored to normal pressure, and the samples were taken out for testing. The thickness, transmittance, hardness and adhesion of the coatings are listed in Table 1 below.

[0093] Example 5

[0094] After cleaning and drying, transparent PC (polycarbonate) plastic parts and black PC plastic parts are placed on the bracket of the reaction chamber of the plasma coating equipment. The back vacuum is pumped to 20mT, and 200sccm of argon gas is introduced. When the pressure stabilizes at 55mT, the chamber discharge is turned on, and the ICP power is set to 600w, the duty cycle is 10%, the bias voltage is 300V, and the processing time is 10min to clean and activate the substrate.

[0095] Octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane were mixed evenly in a mass ratio of 10:1, and two upper and lower feed ports were set with flow rates of 160 μl / min respectively. 65 sccm of oxygen and 50 sccm of argon were introduced, and the vacuum degree was maintained at 50 mT. The discharge was turned on and the ICP power was set to 400 W. The bias voltage was loaded at 200 V, the duty cycle was 30%, and the coating time was 90 min to form a hardened coating.

[0096] After the coating was completed, the chamber was restored to normal pressure, and the samples were taken out for coating thickness, transmittance, hardness and adhesion tests, which are listed in Table 1 below.

[0097] Example 6

[0098] After cleaning and drying, transparent PC (polycarbonate) plastic parts and black PC plastic parts are placed on the bracket of the reaction chamber of the plasma coating equipment. The back vacuum is pumped to 20mT, and 200sccm of argon gas is introduced. When the pressure stabilizes at 55mT, the chamber discharge is turned on, and the ICP power is set to 600w, the duty cycle is 10%, the bias voltage is 300V, and the processing time is 10min to clean and activate the substrate.

[0099] Octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane were mixed evenly in a mass ratio of 10:1, and two upper and lower feed ports were set with flow rates of 160 μl / min respectively. Argon was introduced at 115 sccm, and the vacuum was maintained at 50 mT. The discharge was turned on and the ICP power was set to 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 hardened coating.

[0100] After the coating was completed, the chamber was restored to normal pressure, and the samples were taken out for coating thickness, transmittance, hardness and adhesion tests, which are listed in Table 1 below.

[0101] Example 7

[0102] After cleaning and drying, transparent PC (polycarbonate) plastic parts and black PC plastic parts are placed on the bracket of the reaction chamber of the plasma coating equipment. The back vacuum is pumped to 20mT, and 200sccm of argon gas is introduced. When the pressure stabilizes at 55mT, the chamber discharge is turned on, and the ICP power is set to 600w, the duty cycle is 10%, the bias voltage is 300V, and the processing time is 10min to clean and activate the substrate.

[0103] Octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane were mixed evenly in a mass ratio of 10:1, and two upper and lower feed ports were set with flow rates of 160 μl / min respectively. 115 sccm of oxygen was introduced, and the vacuum degree was maintained at 50 mT. The discharge was turned on and the ICP power was set to 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 hardened coating.

[0104] After the coating was completed, the chamber was restored to normal pressure, and the samples were taken out for coating thickness, transmittance, hardness and adhesion tests, which are listed in Table 1 below.

[0105] Example 8

[0106] After cleaning and drying, transparent PC (polycarbonate) plastic parts and black PC plastic parts are placed on the bracket of the reaction chamber of the plasma coating equipment. The back vacuum is pumped to 20mT, and 200sccm of argon gas is introduced. When the pressure stabilizes at 55mT, the chamber discharge is turned on, and the ICP power is set to 600w, the duty cycle is 10%, the bias voltage is 300V, and the processing time is 10min to clean and activate the substrate.

[0107] Octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane were mixed evenly in a mass ratio of 10:1, and two upper and lower feed ports were set with flow rates of 160 μl / min respectively. 65 sccm of oxygen and 50 sccm of argon were introduced, and the vacuum degree was maintained at 50 mT. The discharge was turned on and the ICP power was set to 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 hardened coating.

[0108] After the coating was completed, the chamber was restored to normal pressure, and the samples were taken out for coating thickness, transmittance, hardness and adhesion tests, which are listed in Table 1 below.

[0109] Example 9

[0110] After cleaning and drying, transparent PC (polycarbonate) plastic parts and black PC plastic parts are placed on the bracket of the reaction chamber of the plasma coating equipment. The back vacuum is pumped to 20mT, and 200sccm of argon gas is introduced. When the pressure stabilizes at 55mT, the chamber discharge is turned on, and the ICP power is set to 600w, the duty cycle is 10%, the bias voltage is 300V, and the processing time is 10min to clean and activate the substrate.

[0111] Tetraethyl orthosilicate and 3-aminopropyltrimethoxysilane were mixed evenly in a mass ratio of 5:1, and two upper and lower feed ports were set with flow rates of 160 μl / min respectively. 65 sccm of oxygen and 50 sccm of argon were introduced, and the vacuum degree was maintained at 50 mT. The discharge was turned on and the ICP power was set to 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 hardened coating.

[0112] After the coating was completed, the chamber was restored to normal pressure, and the samples were taken out for coating thickness, transmittance, hardness and adhesion tests, which are listed in Table 1 below.

[0113] Example 10

[0114] After cleaning and drying, transparent PC (polycarbonate) plastic parts and black PC plastic parts are placed on the bracket of the reaction chamber of the plasma coating equipment. The back vacuum is pumped to 20mT, and 200sccm of argon gas is introduced. When the pressure stabilizes at 55mT, the chamber discharge is turned on, and the ICP power is set to 600w, the duty cycle is 10%, the bias voltage is 300V, and the processing time is 10min to clean and activate the substrate.

[0115] Octamethyltrisiloxane and 3-(2,3-epoxypropyloxy)propyltrimethoxysilane were mixed uniformly in a mass ratio of 1:1, and two upper and lower feed ports were set with flow rates of 160 μl / min respectively. 65 sccm of oxygen and 50 sccm of argon were introduced, and the vacuum degree was maintained at 50 mT. The discharge was turned on and the ICP power was set to 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 hardened coating.

[0116] After the coating was completed, the chamber was restored to normal pressure, and the samples were taken out for coating thickness, transmittance, hardness and adhesion tests, which are listed in Table 1 below.

[0117] Example 11

[0118] After cleaning and drying, transparent PC (polycarbonate) plastic parts and black PC plastic parts are placed on the bracket of the reaction chamber of the plasma coating equipment. The back vacuum is pumped to 20mT, and 200sccm of argon gas is introduced. When the pressure stabilizes at 55mT, the chamber discharge is turned on, and the ICP power is set to 600w, the duty cycle is 10%, the bias voltage is 300V, and the processing time is 10min to clean and activate the substrate.

[0119] Octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane were mixed evenly in a mass ratio of 10:1, and two upper and lower feed ports were set with flow rates of 160 μl / min respectively. 65 sccm of oxygen and 50 sccm of argon were introduced, and the vacuum degree was maintained at 50 mT. The discharge was turned on and the ICP power was set to 1000 W. The bias voltage was loaded to 450 V, the duty cycle was 30%, and the coating time was 90 min to form a hardened coating.

[0120] After the coating was completed, the chamber was restored to normal pressure, and the samples were taken out for coating thickness, transmittance, hardness and adhesion tests, which are listed in Table 1 below.

[0121] Example 12

[0122] After cleaning and drying, transparent PC (polycarbonate) plastic parts and black PC plastic parts are placed on the bracket of the reaction chamber of the plasma coating equipment. The back vacuum is pumped to 20mT, and 200sccm of argon gas is introduced. When the pressure stabilizes at 55mT, the chamber discharge is turned on, and the ICP power is set to 600w, the duty cycle is 10%, the bias voltage is 300V, and the processing time is 10min to clean and activate the substrate.

[0123] Octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane were mixed evenly in a mass ratio of 10:1, and two upper and lower feed ports were set with flow rates of 160 μl / min respectively. 65 sccm of oxygen and 50 sccm of argon were introduced, and the vacuum degree was maintained at 50 mT. The discharge was turned on and the ICP power was set to 400 W. The bias voltage was loaded at 450 V, the duty cycle was 40%, and the coating time was 90 min to form a hardened coating.

[0124] After the coating was completed, the chamber was restored to normal pressure, and the samples were taken out for coating thickness, transmittance, hardness and adhesion tests, which are listed in Table 1 below.

[0125] Comparative Example 1

[0126] Transparent PC plastic parts and black PC plastic parts without coating blank samples were tested for transmittance and are listed in Table 1 below.

[0127] Comparative Example 2

[0128] After cleaning and drying, transparent and black PC (polycarbonate) plastic parts were placed on a support in the reaction chamber of a plasma coating machine. Octamethylcyclotetrasiloxane was introduced through two inlets, one at the top and one at the bottom, at a flow rate of 160 μl / min, with 65 sccm of oxygen and 50 sccm of argon flowing through. A vacuum of 50 mT was maintained. The discharge was initiated, with an ICP power of 700 W, a bias voltage of 450 V, a duty cycle of 30%, and a coating time of 90 minutes to form a hardened coating.

[0129] After the coating was completed, the chamber was restored to normal pressure, and the samples were taken out for coating thickness, transmittance, hardness and adhesion tests, which are listed in Table 1 below.

[0130] Comparative Example 3

[0131] After cleaning and drying, transparent PC (polycarbonate) plastic parts and black PC plastic parts are placed on the bracket of the reaction chamber of the plasma coating equipment. The back vacuum is pumped to 20mT, and 200sccm of argon gas is introduced. When the pressure stabilizes at 55mT, the chamber discharge is turned on, and the ICP power is set to 600w, the duty cycle is 10%, the bias voltage is 300V, and the processing time is 10min to clean and activate the substrate.

[0132] Octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane were mixed evenly in a mass ratio of 10:1, and two upper and lower feed ports were set with flow rates of 160 μl / min respectively. 65 sccm of oxygen and 50 sccm of argon were introduced, and the vacuum degree was maintained at 50 mT. The discharge was turned on and the ICP power was set to 400 W. No bias voltage was loaded, the duty cycle was 30%, and the coating time was 90 min to form a hardened coating.

[0133] After the coating was completed, the chamber was restored to normal pressure, and the samples were taken out for coating thickness, transmittance, hardness and adhesion tests, which are listed in Table 1 below.

[0134] Comparative Example 4

[0135] After cleaning and drying, transparent PC (polycarbonate) plastic parts and black PC plastic parts are placed on the bracket of the reaction chamber of the plasma coating equipment. The back vacuum is pumped to 20mT, and 200sccm of argon gas is introduced. When the pressure stabilizes at 55mT, the chamber discharge is turned on, and the ICP power is set to 600w, the duty cycle is 10%, the bias voltage is 300V, and the processing time is 10min to clean and activate the substrate.

[0136] Octamethylcyclotetrasiloxane was prepared by setting two upper and lower feed ports with flow rates of 160 μl / min, introducing 65 sccm of oxygen and 50 sccm of argon, maintaining a vacuum degree of 50 mT, starting discharge and setting the ICP power to 400 W, loading the bias voltage to 450 V, the duty cycle to 30%, and coating time to 90 min to form a hardened coating.

[0137] After the coating was completed, the chamber was restored to normal pressure, and the samples were taken out for coating thickness, transmittance, hardness and adhesion tests, which are listed in Table 1 below.

[0138] Comparative Example 5

[0139] After cleaning and drying, transparent PC (polycarbonate) plastic parts and black PC plastic parts are placed on the bracket of the reaction chamber of the plasma coating equipment. The back vacuum is pumped to 20mT, and 200sccm of argon gas is introduced. When the pressure stabilizes at 55mT, the chamber discharge is turned on, and the ICP power is set to 600w, the duty cycle is 10%, the bias voltage is 300V, and the processing time is 10min to clean and activate the substrate.

[0140] Two upper and lower feed ports were set, the flow rate of γ-methacryloxypropyltrimethoxysilane was 160 μl / min, 65 sccm of oxygen and 50 sccm of argon were introduced, the vacuum degree was maintained at 50 mT, the discharge was turned on and the ICP power was set to 400 W, the bias voltage was loaded to 450 V, the duty cycle was 30%, and the coating time was 90 min to form a hardened coating.

[0141] After the coating was completed, the chamber was restored to normal pressure, and the samples were taken out for coating thickness, transmittance, hardness and adhesion tests, which are listed in Table 1 below.

[0142] Table 1 Test results of Examples 1-12 and Comparative Examples 1-5

[0143] According to the results in Table 1 above, by using short saturated carbon chain organosilicon and organosilicon with epoxy group, unsaturated carbon-carbon bond or amino group as monomers as raw materials, plasma excitation, and adjusting the power, duty cycle and bias voltage of plasma discharge, the coating with excellent hardness, color difference and adhesion is prepared. Among them, in Comparative Example 4, when only octamethylcyclotetrasiloxane is used, although the hardness is good, the adhesion is relatively poor. In Comparative Example 5, only γ-methacryloxypropyltrimethoxysilane is used, although the hardness is good, the adhesion is relatively poor. The adhesion is good, but the hardness is relatively poor and the color difference becomes larger. In Comparative Example 3, although octamethylcyclotetrasiloxane and γ-methacryloxypropyltrimethoxysilane are used at the same time, the hardness and adhesion are not very good, and the color difference is large because no bias voltage is loaded. However, as in Example 4, the bias voltage should not be too large, as excessive bias voltage will lead to reduced adhesion. According to Examples 3 and 11, if the power is too low, below 200W, the adhesion and hardness will deteriorate and the color difference will become larger. If the power is too high, exceeding 1000W, the color difference will become larger.

[0144] 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 scope of protection of the present invention should be based on 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 represented by the following formula (1), formula (2), or formula (3) and a silicone monomer of the structure represented 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 of 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, 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; The hardness of the coating is tested with a KLA nanoindenter 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 with a KLA nanoindenter 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 said R1 is methyl or ethyl, and the said R2 is methyl or ethyl.

4. The coating according to claim 1, wherein, The organosilicon with the structure shown in 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 organosilicon with the structure shown in 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 organosilicon with 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, 3H,5H - octamethyltetrasiloxane.

7. The coating according to claim 1, wherein The silicone having the structure shown in the formula (4) has the structure shown in 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 the following formulas (6), (7), (8), (9), vinyl or amino group, 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, characterized in that, 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, wherein 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, instrument panel, bumper, exhaust manifold, lamp housing or interior trim.

12. A method for preparing a surface hardening coating for a vehicle plastic part according to 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 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 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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