Coating treatment process, application of treatment liquid and electronic equipment

Abstract

The invention relates to the technical field of metal surface machining, in particular to a coating treatment process, application of treatment liquid and electronic equipment. The coating treatment process comprises the following steps: enabling an electrophoretic coating of a target workpiece to be in contact with a treating fluid comprising a silane coupling agent and lithium silicate water glass; and heating the target workpiece, so that the silane coupling agent is respectively crosslinked and cured with the electrophoresis coating and the lithium silicate, and a target layer is formed on the surface of the electrophoresis coating.

Description

Technical Field

[0001] This application relates to the technical field of metal surface processing, and particularly to a coating treatment process, the application of a treatment liquid, and an electronic device. Background Art

[0002] With the improvement of the quality requirements for 3C products, the product housing needs to meet requirements such as high brightness and multiple colors. Currently, electrophoresis is mostly used to coat the product housing to form an appearance layer, but the obtained coating has poor resistance. Summary of the Invention

[0003] In view of this, the technical problem to be solved by this application is to provide a coating treatment process, the application of a treatment liquid, and an electronic device.

[0004] This application provides a coating treatment process, including:

[0005] Bringing the electrophoretic coating of the target workpiece into contact with a treatment liquid including a silane coupling agent and lithium silicate water glass,

[0006] Heating the target workpiece to cause the silane coupling agent to crosslink and cure with the electrophoretic coating and lithium silicate respectively, and form a target layer on the surface of the electrophoretic coating.

[0007] This application provides an application of the treatment liquid after curing as a protective layer for the electrophoretic coating. The protective layer is provided on the outer surface of the electrophoretic coating as the appearance coating of the workpiece, realizing the improvement of the weather resistance of the electrophoretic coating, and the appearance coating meets the light transmission condition;

[0008] The treatment liquid includes:

[0009] Silane coupling agent 10 - 20 g / L;

[0010] Lithium silicate water glass 15 - 25 g / L.

[0011] This application provides an electronic device, which includes:

[0012] A housing having an electrophoretic topcoat layer;

[0013] A protective layer is provided on the outer surface of the electrophoretic topcoat layer, and the protective layer serves as the appearance layer of the housing;

[0014] The protective layer includes a crosslinked silane coupling agent and lithium silicate, and the silane coupling agent crosslinks with the electrophoretic topcoat layer. Brief Description of the Drawings

[0015] Figure 1 It is a flowchart of the coating treatment process provided by this application. Detailed Description of the Embodiments

[0016] It should be noted that, without conflict, the embodiments in the present application and the technical features in the embodiments can be combined with each other. The detailed description in the specific implementation manners should be understood as an explanatory illustration of the purpose of the present application and should not be regarded as an improper limitation of the present application.

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will further describe the specific technical solutions of the present application in detail with reference to the accompanying drawings in the embodiments of the present application. The following embodiments are used to illustrate the present application but are not used to limit the scope of the present application.

[0018] In the embodiments of the present application, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present application, unless otherwise specified, the meaning of "a plurality" is two or more.

[0019] In addition, in the embodiments of the present application, orientation terms such as "upper", "lower", "left", and "right" are defined relative to the orientation in which the components in the drawings are schematically placed. It should be understood that these directional terms are relative concepts, which are used for relative description and clarification, and they may change correspondingly according to the change in the orientation in which the components in the drawings are placed.

[0020] In the embodiments of the present application, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral body; it can be directly connected or indirectly connected through an intermediate medium.

[0021] In the embodiments of the present application, the terms "include", "comprise", or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device including a series of elements not only includes those elements but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article, or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article, or device including such element.

[0022] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner.

[0023] At present, the hardness and wear resistance of the transparent electrophoretic coating formed by the conventional process are weak, and the protection of active metal substrates has limitations.

[0024] To further improve the hardness and wear resistance of the electrophoretic paint, this application provides a coating treatment process, including:

[0025] Contact the electrophoretic coating of the target workpiece with a treatment solution including a silane coupling agent and lithium silicate water glass;

[0026] Heat the target workpiece to cause the silane coupling agent to crosslink and cure with the electrophoretic coating and lithium silicate respectively, and form a target layer on the surface of the electrophoretic coating.

[0027] By adding an organosilicon-inorganic silicon protective coating on the surface of the electrophoretic topcoat in this application, the resistance of the overall coating is improved, and a workpiece with high transparency, high brightness, high hardness and high wear resistance is obtained.

[0028] In some embodiments of this application, the electrophoretic coating can be an epoxy electrophoretic coating and / or an acrylic electrophoretic coating, etc.

[0029] A large number of R-Si-OH groups are generated by the hydrolysis of the silane coupling agent and dispersed in the solution. During the heating and curing process, R-Si-OH reacts with the remaining -OH, -COOH and other groups on the surface of the electrophoretic coating to form ether bonds, thereby generating crosslinking and curing, and forming a dense protective layer on the surface of the electrophoretic coating.

[0030] Lithium silicate water glass is also added to the treatment solution to form an organosilicon-inorganic silicon mixed solution with the silane coupling agent, and the two can form Si-O-Si bonds during the heating and curing process, further improving the hardness and toughness of the protective layer.

[0031] In some embodiments of this application, the silane coupling agent can be KH-560 silane coupling agent.

[0032] In some embodiments of this application, the content of the silane coupling agent can be 10-20 g / L.

[0033] In some embodiments of this application, the content of the silane coupling agent can be 10, 12, 15, 18 or 20 g / L, or a range value with any of the above values as the upper or lower limit.

[0034] In some embodiments of this application, the content of the lithium silicate water glass can be 15-25 g / L.

[0035] In some embodiments of this application, the content of the lithium silicate water glass can be 15, 20 or 25 g / L, or a range value with any of the above values as the upper or lower limit.

[0036] In some embodiments of the present application, the mass ratio of the silane coupling agent to the lithium silicate water glass may be 1:(1-1.5).

[0037] The protective layer formed by the silane coupling agent and the lithium silicate water glass in the above ratio has the best hardness and toughness, and can effectively avoid the problem that the electrophoretic coating is prone to peeling as the appearance layer in the traditional process. When the dosage of the lithium silicate water glass is lower than the above range, the hardness of the formed protective layer is insufficient and the wear resistance is poor. When the dosage of the lithium silicate water glass is higher than the above range, the formed protective layer is too brittle and lacks toughness, and neither can meet the use requirements.

[0038] In some embodiments of the present application, the treatment liquid may further include polyethylene glycol.

[0039] A large number of -OH groups are contained in the structure of the polyethylene glycol. During the heating and curing process, the R-OH groups can not only react with the remaining -OH, -COOH and other groups on the surface of the electrophoretic coating to form ether bonds, but also a large number of Si-O-Si and Si-O-R bonds are formed between the R-OH groups in the structure of the polyethylene glycol and the Si-OH groups in the structure of the silane coupling agent, thereby generating crosslinking curing and further improving the toughness of the protective layer.

[0040] The solvent of the treatment liquid provided by the present application can be water.

[0041] The addition of polyethylene glycol increases the film-forming property of the aqueous system, makes the treatment liquid easier to form a film on the surface of the workpiece, easier to adhere to the surface of the electrophoretic layer, and at the same time improves the density of the film layer.

[0042] In some embodiments of the present application, the polyethylene glycol may be polyethylene glycol 400.

[0043] In some embodiments of the present application, the content of the polyethylene glycol may be 50-70 g / L.

[0044] In some embodiments of the present application, the content of the polyethylene glycol may be 50, 60 or 70 g / L, or a range value with any of the above values as the upper or lower limit.

[0045] In some embodiments of the present application, the electrophoretic coating may be an acrylic electrophoretic coating. For the acrylic electrophoretic coating in the present application, acrylic resin may be further added to the treatment liquid.

[0046] The acrylic resin can undergo a crosslinking reaction with the remaining -OH, -COOH and other groups on the surface of the acrylic electrophoretic coating, which can further improve the bonding force between the protective layer and the electrophoretic coating and increase the toughness of the protective layer.

[0047] In some embodiments of the present application, the content of the acrylic resin may be 5 to 10 g / L.

[0048] In some embodiments of the present application, the content of the acrylic resin may be 5, 7, 9, or 10 g / L, or a range value with any of the above values as the upper or lower limit.

[0049] In some embodiments of the present application, the treatment liquid may further include nano-silica to improve the hardness and wear resistance of the target layer.

[0050] In some embodiments of the present application, the mass content of the nano-silica in the treatment liquid may be controlled within 0.3% to 0.5%. Within this content range, the nano-silica can not only improve the wear resistance but also have no significant impact on the light transmittance, meeting the light transmission conditions of the protective layer.

[0051] In some embodiments of the present application, the mass content of the nano-silica in the treatment liquid may be 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%, or a range value with any of the above values as the upper or lower limit.

[0052] In some embodiments of the present application, the treatment liquid may further include nano-zinc oxide, which can effectively absorb ultraviolet light to improve the UV resistance of the target layer.

[0053] In some embodiments of the present application, the mass content of the nano-zinc oxide in the treatment liquid may be controlled within 0.1% to 0.3%. Within this content range, the nano-silica can not only improve the UV resistance but also have no significant impact on the light transmittance, meeting the light transmission conditions of the protective layer.

[0054] In some embodiments of the present application, the mass content of the nano-zinc oxide in the treatment liquid may be 0.1%, 0.2%, or 0.3%, or a range value with any of the above values as the upper or lower limit.

[0055] Through the interaction between the above substances, a nano-protective coating is formed on the surface of the acrylic electrophoretic coating. This film layer not only has good compatibility and adhesion with the acrylic coating but also further improves the wear resistance, hardness, and UV resistance of the cathodic electrophoretic paint coating on the surface of the magnesium alloy by forming an organic-inorganic silicon nano-film layer filled with nano-inorganic materials, comprehensively improving the weather resistance of the electrophoretic coating and meeting the higher requirements of product quality.

[0056] In some embodiments of the present application, the target layer serves as the appearance layer of the target workpiece, which is used to improve the weather resistance of the electrophoretic coating and meet the light transmission conditions, endowing the workpiece with the characteristics of high brightness, high transparency, high hardness, and high wear resistance.

[0057] The so-called meeting the light transmission condition means that the light transmittance is greater than 0%. In some embodiments, the light transmittance can be greater than 92%. In other embodiments, the light transmittance can be 92% - 93%.

[0058] In this application, the appearance layer refers to the outermost layer of the product housing coating that is in direct contact with consumers.

[0059] In some embodiments of this application, the temperature for heating the target workpiece can be 130 - 150°C. Under this temperature condition, the silane coupling agent can crosslink and cure with the electrophoretic coating and lithium silicate respectively, forming a dense protective layer on the surface of the electrophoretic coating. If the temperature is lower than this range, the crosslinking reaction cannot occur sufficiently, affecting the density, wear resistance, and hardness of the protective layer. If the heating temperature is higher than the above range, the lithium silicate hardens relatively quickly, forming a film layer with relatively concentrated stress, which is prone to cracking and the bonding force with the substrate decreases.

[0060] In some embodiments of this application, the heating time for the target workpiece can be 10 - 20 min. If the heating time is too short, the crosslinking reaction is not complete enough, affecting the curing degree of the protective layer. If the heating time is too long, it is easy to cause the underlying substrate to continue to oxidize, easily resulting in a decrease in the bonding force between the micro-arc oxidation layer of the workpiece and the substrate, thus causing the failure of the overall workpiece.

[0061] In some embodiments of this application, the coating treatment process can include:

[0062] Performing cathodic electrophoretic treatment and curing on the surface of the target workpiece to form an electrophoretic coating on the workpiece surface;

[0063] Bringing the above electrophoretic coating into contact with a treatment solution including a silane coupling agent and lithium silicate water glass;

[0064] Heating the target workpiece to crosslink and cure the silane coupling agent with the electrophoretic coating and lithium silicate respectively, forming a target layer on the surface of the electrophoretic coating.

[0065] In some embodiments of this application, the target workpiece is a magnesium alloy workpiece.

[0066] Magnesium alloy materials have a wide range of applications in many fields such as automobiles, electronic communications, aerospace, and national defense due to their advantages of low density, high strength, good thermal conductivity, and easy processing and forming. Especially as 3C products, such as the casings of laptops, a bright appearance effect can be obtained. However, the corrosion resistance of magnesium alloys is poor, and surface treatment must be carried out during actual application. As the casing of a laptop, in order to obtain a bright and highly transparent appearance effect, electrophoretic coating technology is generally used to form an electrophoretic coating on the outermost layer. Although it can improve the aesthetics and corrosion resistance of the magnesium alloy casing, the hardness and wear resistance of the electrophoretic coating are insufficient. In easily worn positions, such as the sides, or the positions on the A and C casings of the laptop that are often touched by hands, it is easy to cause the peeling of the electrophoretic coating, affecting the aesthetics of the product.

[0067] In this application, an organosilicon-inorganic silicon protective coating is added on the surface of the electrophoretic topcoat. This protective coating has high wear resistance and hardness, avoids the problem of coating peeling, and greatly improves the service life of the product.

[0068] In some embodiments of this application, the cathodic electrophoretic treatment can be cathodic acrylic electrophoretic treatment.

[0069] In some embodiments of this application, the target workpiece surface is subjected to cathodic electrophoretic treatment and cured, and the electrophoretic coating formed on the workpiece surface is the topcoat layer.

[0070] In some embodiments of this application, before the electrophoretic treatment, it may further include:

[0071] Performing pretreatment on the workpiece.

[0072] This application does not limit the process and steps of the pretreatment, and it can be any pretreatment well-known to those skilled in the art before the appearance layer electrophoretic treatment of the workpiece.

[0073] In some embodiments of this application, the pretreatment may include one or more of CNC high gloss, polishing, degreasing, dewaxing, etc.

[0074] This application does not limit the specific operation of the above CNC high gloss. The surface of the die-cast part can be finely processed by a CNC numerical control machine at high speed to achieve the high gloss effect.

[0075] This application does not limit the specific operation of the above polishing. A polishing wheel can be used to polish the surface of the die-cast part to form a high gloss metal surface. A polishing paste can be used during the polishing process, and the polishing paste includes but is not limited to at least one of petrolatum, paraffin wax, stearic acid, etc.

[0076] This application does not limit the specific operation of the above degreasing, and it can be the degreasing treatment of the metal surface well-known in the art.

[0077] This application does not limit the specific operation of the above wax removal. The surface after polishing can be subjected to wax removal treatment using a wax remover.

[0078] This application does not limit the sequence of degreasing and wax removal. Degreasing can be carried out first and then wax removal, or wax removal can be carried out first and then degreasing.

[0079] In some embodiments of this application, before the cathodic electrophoresis treatment of the surface of the target workpiece, it may further include: setting a primer.

[0080] The above-mentioned primer includes, but is not limited to, one or more of a transparent conversion film, a polymer film, a primer applied by spraying or electrophoretic coating, etc.

[0081] The setting of the above-mentioned primer can be freely adjusted according to the performance requirements of the product, and this application does not limit it.

[0082] This application does not limit the position where the coating treatment process is implemented.

[0083] In some embodiments of this application, the coating treatment process can be used for workpieces, such as the casings of 3C products such as laptop computers, including but not limited to positions such as the easily worn sides of the product casing and the product logo surface, and a casing with a high-brightness side appearance or a casing with a high-brightness logo can be obtained.

[0084] In some embodiments of this application, the coating treatment process can also be used for the overall painting of the workpiece casing.

[0085] In some embodiments of this application, the casing is a magnesium alloy casing.

[0086] This application does not limit the way the electrophoretic coating contacts the treatment liquid, which can be dipping, spraying and other methods well-known to those skilled in the art. Those skilled in the art can select according to the position where the coating treatment is carried out.

[0087] Exemplarily, when the position of the coating treatment is the side of the workpiece casing or the product logo surface, etc., the treatment liquid can be sprayed onto the position to be treated by spraying.

[0088] Exemplarily, when the position of the coating treatment is the overall painting of the workpiece casing, the dipping method can be adopted to make the treatment liquid fully contact the workpiece casing.

[0089] This application provides the application of the treatment liquid after curing as a protective layer for the electrophoretic coating. The protective layer is arranged on the outer surface of the electrophoretic coating as the appearance coating of the workpiece, realizing the improvement of the weather resistance of the electrophoretic coating, and the appearance coating meets the light transmission conditions;

[0090] The treatment liquid includes:

[0091] Silane coupling agent: 10 - 20 g / L;

[0092] Lithium silicate water glass: 15 - 25 g / L.

[0093] In some embodiments of the present application, the treatment liquid includes:

[0094] Silane coupling agent: 10 - 20 g / L;

[0095] Polyethylene glycol: 50 - 70 g / L;

[0096] Lithium silicate water glass: 15 - 25 g / L.

[0097] In some embodiments of the present application, the treatment liquid includes:

[0098]

[0099] In some embodiments of the present application, the treatment liquid further includes:

[0100] Nanosilica: 0.3 wt% - 0.5 wt%.

[0101] In some embodiments of the present application, the treatment liquid further includes:

[0102] Nanozinc oxide: 0.1 wt% - 0.3 wt%.

[0103] In some embodiments of the present application, the silane coupling agent can be KH - 560 silane coupling agent.

[0104] In some embodiments of the present application, the polyethylene glycol can be polyethylene glycol 400.

[0105] In some embodiments of the present application, the mass ratio of the silane coupling agent to the lithium silicate water glass can be 1:(1 - 1.5).

[0106] The present application provides an electronic device, and the electronic device includes:

[0107] A housing, the housing having an electrophoretic topcoat layer;

[0108] A protective layer is provided on the outer surface of the electrophoretic topcoat layer, and the protective layer serves as the appearance layer of the housing;

[0109] The protective layer includes a crosslinked silane coupling agent and lithium silicate, and the silane coupling agent is crosslinked with the electrophoretic topcoat layer.

[0110] In some embodiments of the present application, the housing is a magnesium alloy housing.

[0111] In some embodiments of the present application, the housing is a magnesium alloy housing and includes a first surface having a metallic mirror effect.

[0112] Optionally, the magnesium alloy housing includes a first surface and a second surface, the first surface intersects with the second surface, the first surface has a first appearance effect; the second surface has a second appearance effect different from the first appearance effect, and the first appearance effect is a metallic mirror effect.

[0113] Optionally, there is a third surface at the junction of the first surface and the second surface, the size of the third surface is smaller than that of the first surface and the second surface, and the third surface has the first appearance effect or the second appearance effect.

[0114] Optionally, both the first surface and the second surface are flat surfaces.

[0115] The above coating treatment process provided by the present application realizes a high-brightness and high-transparency effect on the surface of the magnesium alloy. Due to the high-hardness and high-wear-resistant characteristics of the outermost protective layer, the high-brightness and high-transparency coating on the surface of the magnesium alloy is more wear-resistant and not easy to peel off. The prepared electronic device can be applied to more complex working conditions, such as the casings of handheld devices, the casings of biomedical products, the casings of consumer electronic products, etc. It not only gives play to the advantages of the magnesium alloy being light in weight and high in strength, but also solves the disadvantage of the poor corrosion resistance of the magnesium alloy, expanding the application field of the magnesium alloy material.

[0116] The present application also provides an electronic device including the above electronic equipment.

[0117] To further illustrate the present application, it will be described in detail below in conjunction with embodiments. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present application, rather than limiting the claims of the application.

[0118] There are no special restrictions on the sources of all raw materials of the present application, and they can be purchased on the market or prepared according to the conventional methods well-known to those skilled in the art.

[0119] In the following examples and comparative examples, the workpieces used are magnesium alloy workpieces.

[0120] The pretreatment includes successively: CNC high gloss, polishing, dewaxing, and degreasing.

[0121] Example 1

[0122] Composition of the treatment liquid:

[0123]

[0124]

[0125] The treatment process is asFigure 1 As shown, after the pretreatment of the magnesium alloy workpiece by CNC high-gloss, polishing, dewaxing, and degreasing, cathodic acrylic electrophoresis treatment is carried out and baked and cured. Then, the workpiece is cooled and immersed in the above treatment liquid. After taking out and draining, it is heated and cured to form a nano-protective coating, and this nano-protective coating is the appearance layer of the product.

[0126] Among them, the temperature for baking and curing the electrophoretic paint is 25 °C; the time is 60 s;

[0127] The temperature for heating and curing to form the nano-protective coating is 130 °C, and the time is 15 min.

[0128] Example 2

[0129] Composition of the treatment liquid:

[0130]

[0131] The treatment process is as Figure 1 As shown, after the pretreatment of the magnesium alloy workpiece by CNC high-gloss, polishing, dewaxing, and degreasing, cathodic acrylic electrophoresis treatment is carried out and baked and cured. Then, the workpiece is cooled and immersed in the above treatment liquid. After taking out and draining, it is heated and cured to form a nano-protective coating.

[0132] Among them, the temperature for baking and curing the electrophoretic paint is 25 °C; the time is 90 s;

[0133] The temperature for heating and curing to form the nano-protective coating is 150 °C, and the time is 10 min.

[0134] Example 3

[0135] Composition of the treatment liquid:

[0136]

[0137]

[0138] The treatment process is as Figure 1 As shown, after the pretreatment of the magnesium alloy workpiece by CNC high-gloss, polishing, dewaxing, and degreasing, cathodic acrylic electrophoresis treatment is carried out and baked and cured. Then, the workpiece is cooled and immersed in the above treatment liquid. After taking out and draining, it is heated and cured to form a nano-protective coating.

[0139] Among them, the temperature for baking and curing the electrophoretic paint is 25 °C; the time is 60 s;

[0140] The temperature for heating and curing to form the nano-protective coating is 130 °C, and the time is 15 min.

[0141] Example 4

[0142] Composition of the treatment liquid:

[0143]

[0144] The processing flow is as follows Figure 1 shown. After the pretreatment of CNC high gloss, polishing, dewaxing, and degreasing of the magnesium alloy workpiece, cathodic acrylic electrophoresis treatment and baking and curing are carried out. Then, the workpiece is cooled and immersed in the above treatment liquid. After taking out and draining, heating and curing are carried out to form a nano protective coating.

[0145] Among them, the temperature for baking and curing the electrophoretic paint is 25°C; the time is 60 s;

[0146] The temperature for heating and curing to form the nano protective coating is 130°C, and the time is 15 min.

[0147] Comparative Example 1

[0148] Composition of the treatment liquid:

[0149]

[0150] The processing flow is as follows Figure 1 shown. After the pretreatment of CNC high gloss, polishing, dewaxing, and degreasing of the magnesium alloy workpiece, cathodic acrylic electrophoresis treatment and baking and curing are carried out. Then, the workpiece is cooled and immersed in the above treatment liquid. After taking out and draining, heating and curing are carried out to form a nano protective coating.

[0151] Among them, the temperature for baking and curing the electrophoretic paint is 25°C; the time is 60 s;

[0152] The temperature for heating and curing to form the nano protective coating is 130°C, and the time is 15 min.

[0153] Comparative Example 2

[0154] Composition of the treatment liquid:

[0155]

[0156] The processing flow is as follows Figure 1 shown. After the pretreatment of CNC high gloss, polishing, dewaxing, and degreasing of the magnesium alloy workpiece, cathodic acrylic electrophoresis treatment and baking and curing are carried out. Then, the workpiece is cooled and immersed in the above treatment liquid. After taking out and draining, heating and curing are carried out to form a nano protective coating.

[0157] Among them, the temperature for baking and curing the electrophoretic paint is 25°C; the time is 60 s;

[0158] The temperature for heating and curing to form the nano protective coating is 130°C, and the time is 15 min.

[0159] Comparative Example 3

[0160] Composition of the treatment liquid:

[0161]

[0162] The processing flow is as follows Figure 1 After the pretreatment of CNC high gloss, polishing, dewaxing and degreasing of the magnesium alloy workpiece, cathodic acrylic electrophoresis treatment is carried out and baked and cured. Then, after the workpiece is cooled, it is immersed in the above treatment liquid, taken out and drained, and then heated and cured to form a nano protection coating.

[0163] Among them, the temperature for baking and curing the electrophoretic paint is 25 °C; the time is 60 s;

[0164] The temperature for heating and curing to form a nano protection coating is 130 °C, and the time is 15 min.

[0165] Comparative Example 4

[0166] Composition of the treatment liquid:

[0167]

[0168] Processing flow: The difference from Example 1 is that after being immersed in the treatment liquid, it is not heated and cured, but directly air-dried.

[0169] After the pretreatment of CNC high gloss, polishing, dewaxing and degreasing of the magnesium alloy workpiece, cathodic acrylic electrophoresis treatment is carried out and baked and cured. Then, after the workpiece is cooled, it is immersed in the above treatment liquid, taken out and drained, and then directly air-dried or dried at low temperature.

[0170] Among them, the temperature for baking and curing the electrophoretic paint is 25 °C; the time is 60 s.

[0171] The results show that the bonding force between the film layer formed on the surface of the workpiece without heating and curing and the electrophoretic coating is very weak and it is easy to peel off.

[0172] Comparative Example 5

[0173] Composition of the treatment liquid:

[0174]

[0175]

[0176] The processing flow is as follows Figure 1 After the pretreatment of CNC high gloss, polishing, dewaxing and degreasing of the magnesium alloy workpiece, cathodic acrylic electrophoresis treatment is carried out and baked and cured. Then, after the workpiece is cooled, it is immersed in the above treatment liquid, taken out and drained, and then heated and cured to form a nano protection coating.

[0177] Among them, the temperature for baking and curing the electrophoretic paint is 25 °C; the time is 60 s;

[0178] The temperature for heat curing to form the nano protective coating is 120 °C, and the time is 15 min.

[0179] The wear resistance, hardness and anti-UV performance of the magnesium alloy workpieces prepared in Examples 1 to 4, Comparative Examples 1 to 3, and Comparative Example 5 were tested, and the results are shown in Table 1.

[0180] Table 1

[0181]

[0182] Among them, the adhesion test was carried out according to the standard of GB / T 9286-2021 "Cross-Cut Test for Paints and Varnishes";

[0183] The hardness test was carried out according to the standard of GB / T 6739-2022 "Determination of Film Hardness by Pencil Method for Paints and Varnishes";

[0184] The test of RCA (tape wear resistance) was carried out according to ASTM F2357-04, that is, the standard of "Standard Test Method for Determining the Abrasion Resistance of Inks and Coatings on Membrane Switches Using the Norman Tool “RCA” Abrader";

[0185] The test of non-discoloration under UV irradiation was carried out according to the ASTM D4587 Paint and Related Coatings UV Condensation Exposures Test standard;

[0186] Although the overall hardness of the coating film formed in Comparative Example 3 was improved, the coating film was brittle and easy to break. The cross-cut test showed that the film layer peeled off fragmentarily.

[0187] Examples 1 to 4, Comparative Examples 1 to 2, 4 to 5 were tested by the cross-cut test, and no cracks or fragmentary peeling occurred in the film layer.

[0188] The description of the above examples is only used to help understand the method and its core idea of this application. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of this application, several improvements and modifications can still be made to this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A coating treatment process, comprising: contacting the electrophoretic coating of the target workpiece with a treatment solution including a silane coupling agent and lithium silicate water glass; The target workpiece is heated to allow the silane coupling agent to crosslink and solidify with the electrophoretic coating and the lithium silicate, respectively, to form a target layer on the surface of the electrophoretic coating.

2. The treatment process according to claim 1, characterized in that: The heating temperature is 130-150°C; The heating time is 10 to 20 minutes.

3. The treatment process according to claim 1, characterized in that: The mass ratio of the silane coupling agent to the lithium silicate water glass is 1:(1-1.5).

4. The treatment process according to claim 1, characterized in that: The electrophoretic coating is an epoxy electrophoretic coating and / or an acrylic electrophoretic coating.

5. The treatment process according to claim 1, characterized in that: The treatment solution also includes polyethylene glycol to improve the toughness of the target layer; And / or, the treatment solution further comprises acrylic resin to improve the toughness of the target layer.

6. The treatment process according to claim 1, characterized in that: The treatment liquid also includes nano-silicon dioxide to improve the wear resistance of the target layer.

7. The treatment process according to claim 1, characterized in that: The treatment solution also includes nano zinc oxide to improve the UV resistance of the target layer.

8. An application of a treatment liquid as a protective layer of an electrophoretic coating after solidification, wherein the protective layer is arranged on the outer surface of the electrophoretic coating as an appearance coating of a workpiece, thereby improving the weather resistance of the electrophoretic coating, and the appearance coating meets the light transmission condition; The treatment liquid comprises: Silane coupling agent 10-20 g / L; Lithium silicate water glass 15~25g / L.

9. The use according to claim 8, characterized in that: The treatment liquid comprises:

10. An electronic device, comprising: A housing having an electrophoretic topcoat layer; The outer surface of the electrophoretic topcoat layer is provided with a protective layer, and the protective layer serves as the appearance layer of the shell; The protective layer includes a silane coupling agent and lithium silicate which are cross-linked with each other, and the silane coupling agent is cross-linked with the electrophoretic topcoat layer.

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