A light-moisture dual-cure epoxy polysilazane coating, and methods of making and using the same

Abstract

The application provides a light-moisture dual-curing epoxy polysilazane coating and a preparation method and use method thereof, and belongs to the technical field of coatings. The coating comprises the following raw materials in parts by weight: alicyclic epoxy resin 10.0-35.0 parts, polysilazane modified epoxy resin 10.0-25.0 parts, dispersing wetting agent 0.3-1.0 parts, defoaming agent 0.1-0.5 parts, filler 5.0-20.0 parts, photoinitiator 1.0-5.0 parts, leveling agent 0.1-0.5 parts, rheological agent 0.1-0.8 parts and organic solvent 6.0-15.0 parts. The light-moisture dual-curing epoxy polysilazane coating provided by the application is a single-component coating that can be applied in a non-ideal coating environment, and has excellent comprehensive performance of corrosion resistance, weather resistance, temperature resistance and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of coatings, and particularly relates to a light-humidity dual-curing epoxy polysilazane coating and a preparation method and use method thereof. BACKGROUND

[0002] Aliphatic epoxy resin has excellent UV resistance, temperature resistance and corrosion resistance, can be rapidly photocured, greatly shortens the on-site coating time, and has very obvious advantages in coating performance and coating construction as a single-component coating. However, the hardness of aliphatic epoxy resin is relatively low, and in the prior art, an epoxy corrosion-resistant material is generally used as a primer, and polyurethane or fluorocarbon is used as a topcoat for a multi-coating scheme. This not only consumes time and effort, but also is difficult to operate in a non-ideal coating environment and pollutes the environment. SUMMARY

[0003] The application provides a light-humidity dual-curing epoxy polysilazane coating and a preparation method and use method thereof. The light-humidity dual-curing epoxy polysilazane coating provided by the application is a single-component coating that can be operated in a non-ideal coating environment, and has excellent comprehensive performance such as corrosion resistance, weather resistance and temperature resistance.

[0004] The application provides a light-humidity dual-curing epoxy polysilazane coating, which comprises the following raw materials in parts by weight: 10.0-35.0 parts of aliphatic epoxy resin, 10.0-25.0 parts of polysilazane modified epoxy resin, 0.3-1.0 parts of dispersing wetting agent, 0.1-0.5 parts of defoaming agent, 5.0-20.0 parts of filler, 1.0-5.0 parts of photoinitiator, 0.1-0.5 parts of leveling agent, 0.1-0.8 parts of rheological agent and 6.0-15.0 parts of organic solvent.

[0005] Preferably, 2.0-15.0 parts of pigment and 2.0-5.0 parts of anti-rust pigment are further included.

[0006] Preferably, the polysilazane modified epoxy resin is obtained by mixing epoxy resin, solvent and polysilazane and performing reflux reaction.

[0007] Preferably, the epoxy resin is bisphenol A type epoxy resin, bisphenol F type epoxy resin or aliphatic epoxy resin.

[0008] Preferably, the mass ratio of the epoxy resin, solvent and polysilazane is (15-30):(20-40):(30-55).

[0009] Preferably, the reflux reaction is performed at a temperature of 175-185 DEG C for 5.5-6.5 h under N2 protection.

[0010] Preferably, the dispersing wetting agent is a polyhexamethylene adipate polyol-polyethylene imine block copolymer type dispersant, an acrylic ester high polymer type dispersant, or a polyurethane or polyester type high polymer dispersant.

[0011] Preferably, the photoinitiator is a diazonium salt, a triaryl sulfonium salt, an alkyl sulfonium salt, an iron arene salt, a sulfonyloxy ketone, or a triaryl silyl ether.

[0012] The present application provides a preparation method of the light-humidity dual-curing epoxy polysilazane coating as described in any one of the above, comprising the following steps:

[0013] 1) mixing an alicyclic epoxy resin and an organic solvent uniformly, then adding a dispersing wetting agent and a defoaming agent to obtain a first mixture;

[0014] 2) adding pigments, fillers, and anti-rust pigments to the first mixture, stirring uniformly, then performing grinding to obtain a grinding slurry;

[0015] 3) conveying the grinding slurry to a paint mixing kettle with nitrogen protection, adding a photoinitiator, a polysilazane modified epoxy resin, a leveling agent, and a rheological agent, stirring uniformly, then filtering and packaging under N2 protection to obtain the light-humidity dual-curing epoxy polysilazane coating.

[0016] The present application provides a use method of the light-humidity dual-curing epoxy polysilazane coating as described in any one of the above, comprising the following steps:

[0017] A. treating a workpiece surface to Sa2.5 or St3, and coating the coating on the workpiece surface;

[0018] B. at normal temperature, waiting for 5-10 min for the coating to naturally level, performing light irradiation for 2-5 min in a 365 nm ultraviolet curing device, and the hardness reaching HB-H.

[0019] Compared with the prior art, the present application has the following advantages and positive effects:

[0020] The light-humidity dual-curing epoxy polysilazane coating provided by the present application uses the UV light curing effect of the alicyclic epoxy resin to shape the coating in the early stage, so that the coating of the coated workpiece has a certain crosslinking degree, thereby being able to quickly dry and the coating hardness reaching the requirements for transportation and packaging and temporary corrosion after light curing for 2-5 min. The coating can be deeply crosslinked and cured by using the curing reaction between the polysilazane modified epoxy resin and the moisture in the air in the later stage, so as to improve the performance of the coating, reach a high crosslinking degree and hardness, and have good corrosion resistance. At the same time, since the epoxy resin and the polysilazane can perform a thermal curing reaction under high temperature conditions, the coating can finally realize a triple curing reaction in the case of high temperature corrosion, and has excellent temperature resistance. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work belong to the scope of protection of the present application.

[0022] The present application provides a light-moisture dual-curing epoxy polysilazane coating, comprising the following raw materials by weight: alicyclic epoxy resin 10.0-35.0 parts, polysilazane modified epoxy resin 10.0-25.0 parts, dispersing wetting agent 0.3-1.0 parts, defoaming agent 0.1-0.5 parts, filler 5.0-20.0 parts, photoinitiator 1.0-5.0 parts, leveling agent 0.1-0.5 parts, rheological agent 0.1-0.8 parts, and organic solvent 6.0-15.0 parts.

[0023] The light-moisture dual-curing epoxy polysilazane coating provided by the present application comprises alicyclic epoxy resin, which comprises 10.0-35.0 parts by weight. In the present application, the alicyclic epoxy resin is the basic component of the coating, which can achieve rapid curing. The specific principle is that under ultraviolet radiation, triarylsulfonium salt generates cation and aryl cation, and then generates strong protonic acid; then the strong protonic acid reacts with the epoxy group to form a hypooxonium ion, and the oxonium ion continues to attack the epoxy group to form a cationic growth chain, completing the conversion of the coating film from liquid phase to solid phase, and finally completing the curing.

[0024] The light-humidity dual-curing epoxy polysilazane coating provided by the present application comprises a polysilazane modified epoxy resin, which comprises 10.0-25.0 parts by weight. In the present application, the polysilazane modified epoxy resin is preferably obtained by mixing an epoxy resin, a solvent and polysilazane and then performing a reflux reaction. In the present application, the epoxy resin is preferably a bisphenol A type epoxy resin, a bisphenol F type epoxy resin or an alicyclic epoxy resin, more preferably a bisphenol A type epoxy resin, and more preferably E06 (epoxy value about 0.06), E12 (epoxy value about 0.12), E20 (epoxy value about 0.20), E44 (epoxy value about 0.44), E51 (epoxy value about 0.51), DER332 (epoxy value about 0.58). In the present application, the solvent is preferably propylene glycol methyl ether acetate. In the present application, the mass ratio of the epoxy resin, the solvent and the polysilazane is preferably (15-30):(20-40):(30-55). In the present application, the reflux reaction is preferably performed at a temperature of 175-185℃ for 5.5-6.5h under N2 protection. After the reflux reaction, a vacuum pump and an electric heater are preferably turned on for distillation until no liquid is extracted, so as to obtain a colorless or light yellow transparent viscous liquid. The viscosity thereof is 8000-12000cps (25℃). It should be noted that the polysilazane modified epoxy resin obtained in the present application is prone to water reaction in the air, and therefore it cannot be exposed to the air during preparation and packaging, transportation and storage.

[0025] In the present application, the polysilazane modified epoxy resin is used to generate a stable prepolymer with Si-O-C and Si-N-C in the main chain and active -CH=CH2 and -H groups in the side chain through ring-opening reaction of the polar Si-N bond and epoxy group. When air or H2O in the medium penetrates into the coating, it will react with the Si-N bond in the main chain to achieve the effect of moisture curing. If the side chain groups undergo addition reaction under heating conditions, the crosslinking density of the coating will significantly increase, providing high barrier shielding property. In addition, the introduction of Si-O bond increases the temperature resistance of the polymer. In the present application, the epoxy part of the polysilazane modified epoxy resin also participates in the photocuring reaction. The present application combines the photocuring aliphatic epoxy and the polysilazane modified epoxy resin, and uses the dual effects of photocuring and moisture curing in the same coating to obtain a high-performance anticorrosion temperature-resistant weather-resistant coating with the advantages of both. The one-coat coating scheme replaces the multi-coat scheme of the commonly used epoxy anticorrosion primer, polyurethane or fluorocarbon topcoat, while shortening the coating time and saving energy and reducing emissions. It has great significance for completing on-site rapid repair and improving the quality of anticorrosion engineering. The polysilazane modified epoxy resin is not only a simple synthesis of coating raw materials, but also causes significant changes in coating curing method and coating process. As a temperature-resistant coating using polysilazane modified epoxy resin and aliphatic epoxy resin as film-forming material, from coating to final use, it becomes part of the anticorrosion workpiece through photocuring, moisture curing. If used in a high-temperature environment, it can also undergo passive heat curing at high temperature to further complete the crosslinking reaction of the coating and fully utilize the excellent temperature resistance of the resin, so that the coating can play a better protective role in harsh high-temperature conditions.

[0026] The light-humidity dual-curing epoxy polysilazane coating provided by the present application comprises a dispersing wetting agent, which comprises 0.3-1.0 parts by weight. In the present application, the dispersing wetting agent is preferably a polyhexamethylene adipate polyol-polyethyleneimine block copolymer dispersant, an acrylate polymer dispersant, or a polyurethane or polyester high molecular dispersant. In the present application, the dispersing wetting agent can wet and disperse fine particle pigments and fillers in the base material and keep the particles in a dispersed state.

[0027] The light-humidity dual-curing epoxy polysilazane coating provided by the present application comprises a defoaming agent, which comprises 0.1-0.5 parts by weight. In the present application, the defoaming agent is preferably mineral oil, amide, polyether, polydimethylsiloxane, or polyether modified silicone oil. In the present application, the defoaming agent mainly eliminates air bubbles generated during coating production and mechanical bubbles generated during coating construction.

[0028] The light-moisture dual curing epoxy polysilazane coating provided by the present application comprises fillers, 5.0-20.0 parts by weight. In the present application, the fillers preferably comprise one or more of mica powder, silicon powder, talc powder, barium sulfate, wollastonite and feldspar powder.

[0029] The light-moisture dual curing epoxy polysilazane coating provided by the present application comprises a photoinitiator, 1.0-5.0 parts by weight. In the present application, the photoinitiator is preferably diazonium salt, triaryl sulfonium salt, alkyl sulfonium salt, iron arene salt, sulfonyloxy ketone or triaryl siloxy ether. In the present application, the photoinitiator is activated by light to make the molecule into an excited state, and the molecule undergoes a series of decomposition reactions, finally producing a super strong protonic acid, which initiates the polymerization of the epoxy compound as a cationic polymerization active species.

[0030] The light-moisture dual curing epoxy polysilazane coating provided by the present application comprises a leveling agent, 0.1-0.5 parts by weight. In the present application, the leveling agent is preferably polydimethylsiloxane, polyether polyester modified organosiloxane, alkyl modified organosiloxane, acrylate leveling agent. In the present application, the leveling agent can promote the formation of a flat, smooth and uniform coating film during the drying and film forming process of the coating. It can effectively reduce the surface tension of the finishing liquid and improve its leveling property and uniformity.

[0031] The light-moisture dual curing epoxy polysilazane coating provided by the present application comprises a rheological agent, 0.1-0.8 parts by weight. In the present application, the rheological agent is preferably hydrogenated castor oil, polyethylene wax, polyamide wax, organic bentonite. In the present application, the rheological agent can prevent the precipitation of pigments and fillers during the storage of the coating, avoid the splashing and sagging of the coating during the coating process, and improve the leveling performance of the coating film.

[0032] The light-moisture dual curing epoxy polysilazane coating provided by the present application comprises an organic solvent, 6.0-15.0 parts by weight. In the present application, the solvent is preferably aromatic, ester or ketone solvent, more preferably xylene, butyl acetate, methyl isobutyl ketone, propylene glycol methyl ether acetate, cyclohexanone, DBE, methyl ethyl ketone, acetone.

[0033] The light-moisture dual curing epoxy polysilazane coating provided by the present application comprises pigments, 2.0-15.0 parts by weight. In the present application, the pigments are preferably azo-free pigments, more preferably one or more of titanium dioxide, red iron oxide, black iron oxide, yellow iron oxide, cobalt black and carbon black.

[0034] The light-humidity dual-curing epoxy polysilazane paint provided by the present application comprises an anti-rust pigment, and the amount of the anti-rust pigment is 2.0-5.0 parts by weight. In the present application, the anti-rust pigment preferably comprises one or more of zinc phosphate, aluminum tripolyphosphate, calcium phosphite and ion exchange type anti-rust pigment.

[0035] The present application provides a preparation method of the light-humidity dual-curing epoxy polysilazane paint described in any one of the above, comprising the following steps:

[0036] 1) uniformly mixing an alicyclic epoxy resin and an organic solvent, and then adding a dispersing wetting agent and a defoaming agent to obtain a first mixture;

[0037] 2) adding pigments, fillers and anti-rust pigments to the first mixture, uniformly stirring, and then performing grinding to obtain a grinding slurry;

[0038] 3) conveying the grinding slurry to a paint mixing kettle with nitrogen protection, adding a photoinitiator, a polysilazane modified epoxy resin, a leveling agent and a rheological agent, uniformly stirring, and then filtering and packaging under N2 protection to obtain the light-humidity dual-curing epoxy polysilazane paint.

[0039] In the present application, the stirring speed in step 2) is preferably 800-1200 rpm. In the present application, the fineness of the grinding slurry is preferably ≤30 μm.

[0040] The present application provides a use method of the light-humidity dual-curing epoxy polysilazane paint described in any one of the above, comprising the following steps:

[0041] A. treating the surface of a workpiece to Sa2.5 or St3, and coating the paint on the surface of the workpiece;

[0042] B. at room temperature, naturally leveling the coating for 5-10 min, and performing light irradiation for 2-5 min in a 365 nm ultraviolet curing device, so that the hardness reaches HB-H.

[0043] In the present application, the coating is performed under the conditions that the air humidity is ≥70%, the temperature is 0-40°C, and the temperature is higher than the dew point temperature by 3°C or more. In the present application, the coating mode preferably comprises airless spraying, air spraying, brushing, rolling, dipping and showering.

[0044] In order to further illustrate the present application, the technical solutions provided by the present application are described in detail below in combination with examples, but they should not be understood as limiting the protection scope of the present application.

[0045] Example 1

[0046] A 1# polysilazane modified epoxy resin is prepared, wherein the amounts and sources of the components are shown in Table 1.

[0047] Table 1

[0048]

[0049] Into a nitrogen filled reaction vessel, 1 (bisphenol A epoxy resin E44) was added, followed by 3 (methyl isobutyl ketone (MIBK)) and 4 (xylene), and after thorough stirring, 2 (polysilazane) was added to the reaction vessel and stirred thoroughly (operating environment humidity < 50%). After warming to 180°C, reflux was started. After 5 hours of reflux, the solution was observed for clarity and transparency, and after 15 minutes when the solution became completely clear and transparent, the vacuum pump and heating were turned on for distillation until no liquid was drawn out, resulting in a colorless or light yellow transparent viscous liquid with a viscosity of 8000-12000 cps (25°C). After cooling to room temperature, the resulting polysilazane modified epoxy resin was filtered and packaged, and because it is prone to air moisture reaction, it cannot be exposed to air during preparation and packaging, transportation and storage.

[0050] Preparation of light-moisture dual-cured polysilazane modified epoxy coating, wherein the amount and source of each component are shown in Table 2:

[0051] Table 2

[0052]

[0053]

[0054] Into a reaction vessel, an alicyclic epoxy resin was added, followed by organic solvents MIBK, xylene and PMA, and after mixing well, a dispersing wetting agent and a defoaming agent were added and stirred well. Pigments, fillers and anti-rust pigments were added, and after high-speed stirring at 1200 rpm, the mixture was transferred to a sand mill and ground to a fineness of < 30 μm. The ground slurry was transferred to a paint mixing kettle under nitrogen protection, and a photoinitiator, a polysilazane modified epoxy resin, a leveling agent and a rheological agent were added and stirred well, and the viscosity was 60-80 s (T-4 cup, 25°C). The mixture was filtered and packaged under N2 protection.

[0055] Construction operation process:

[0056] Diluent / cleaning agent: xylene / MIBK = 2:1

[0057] Air humidity: > 70%

[0058] Temperature: 0-40°C, and more than 3°C above the dew point temperature.

[0059] 1. After the workpiece surface is treated to Sa2.5 or St3 according to the requirements of ISO 8501, the coating is sprayed on the surface of the workpiece.

[0060] 2. At room temperature, after the coating is naturally leveled for 5 min, send it into a 365 nm ultraviolet light curing device (power 2 kW, control light intensity 35 mW / cm 2 ), light exposure time 5 min, hardness ≥ HB.

[0061] 3. After light exposure, it can be directly packaged offline.

[0062] Example 2

[0063] Prepare 2# polysilazane modified epoxy resin, wherein the amount and source of each component are shown in Table 3.

[0064] Table 3

[0065]

[0066] The specific preparation method is the same as that of Example 1, and polysilazane modified epoxy resin is obtained.

[0067] Prepare light-moisture dual-cured polysilazane modified epoxy coating, wherein the amount and source of each component are shown in Table 4:

[0068] Table 4

[0069]

[0070] The specific preparation process and coating process of the light-moisture dual-cured polysilazane modified epoxy coating are the same as those of Example 1.

[0071] Example 3

[0072] Prepare 3# polysilazane modified epoxy resin, wherein the amount and source of each component are shown in Table 5.

[0073] Table 5

[0074]

[0075] The specific preparation method is the same as that of Example 1, and polysilazane modified epoxy resin is obtained.

[0076] Prepare light-moisture dual-cured polysilazane modified epoxy coating, wherein the amount and source of each component are shown in Table 4:

[0077] Table 6

[0078]

[0079]

[0080] The specific preparation process and coating process of the light-moisture dual-cured polysilazane modified epoxy coating are the same as those of Example 1.

[0081] Example 4

[0082] The polysilazane-modified epoxy resin is the 1# polysilazane-modified epoxy resin prepared in Example 1.

[0083] Preparation of the light-moisture dual-curing polysilazane-modified epoxy coating, wherein the amount and source of each component are shown in Table 7:

[0084] Table 7

[0085]

[0086]

[0087] The specific preparation process and coating process of the light-moisture dual-curing polysilazane-modified epoxy coating are the same as those in Example 1.

[0088] Example 5

[0089] The polysilazane-modified epoxy resin is the 1# polysilazane-modified epoxy resin prepared in Example 1.

[0090] Preparation of the light-moisture dual-curing polysilazane-modified epoxy coating, wherein the amount and source of each component are shown in Table 8:

[0091] Table 8

[0092]

[0093] The specific preparation process and coating process of the light-moisture dual-curing polysilazane-modified epoxy coating are the same as those in Example 1.

[0094] Example 6

[0095] The difference from Example 1 is that the light curing time after coating is 10 min during construction operation. The specific process is as follows:

[0096] Construction operation process:

[0097] Diluent / cleaning agent: xylene / MIBK = 2:1

[0098] Air humidity: ≥70%

[0099] Temperature: 0-40℃, and higher than the dew point temperature by more than 3℃.

[0100] 1. After the workpiece surface is treated to Sa2.5 or St3 according to the requirements of ISO 8501, the coating is sprayed on the surface of the workpiece.

[0101] 2. After the coating is naturally leveled for 5 min at room temperature, it is sent into a 365 nm ultraviolet curing device (power 2kW, control light intensity 35mW / cm 2 ), light irradiation time 10 min, hardness ≥F.

[0102] 3. After the completion of the light irradiation, the test panel can be directly packed and sent out.

[0103] Example 7

[0104] The difference from Example 1 is that after the completion of the light irradiation, the test panel is placed in an oven at 200°C for 24 hours and then taken out for testing the coating performance. The main purpose is to observe the change of the coating performance when the coating is used in a high-temperature environment (200-250°C).

[0105] Example 8

[0106] The difference from Example 1 is that after the completion of the light irradiation, the test panel is placed in a constant temperature and humidity chamber at 25°C and humidity ≤30% for 30 days (the test panels of other examples are placed in a constant temperature and humidity chamber at 25°C and humidity 70% for 30 days) and then the coating performance is tested. The main purpose is to observe the influence of the late humidification on the coating after the coating is cured in a long-term dry environment (humidity 30%).

[0107] Comparative Example 1

[0108] The difference from Example 1 is that the photoinitiator is different, and bis (4-dodecyl phenyl) hexafluoroantimony iodine onium salt (PAG31102) is used instead of triaryl hexafluoroantimony sulfonium salt (UVI6976) in Example 1.

[0109] Comparative Example 2

[0110] The difference from Example 1 is that the amount of the epoxy resin used in the preparation of the polysilazane-modified epoxy resin is different, as shown in Table 9.

[0111] Table 9

[0112]

[0113] Comparative Example 3

[0114] The difference from Example 1 is that in the preparation of the light-humidity dual-curing polysilazane-modified epoxy coating, the light-curing main resin cycloaliphatic epoxy resin is replaced by bisphenol A epoxy resin E51, as shown in Table 10.

[0115] Table 10

[0116]

[0117] Comparative Example 4

[0118] The difference from Example 1 is that only cycloaliphatic epoxy resin is used as the main film-forming material in this example, and the amount and source of each component are shown in Table 11.

[0119] Table 11

[0120]

[0121]

[0122] Comparative Example 5

[0123] The difference from Example 1 is that the entire 1# polysilazane modified epoxy resin is used to prepare the coating, as shown in Table 12.

[0124] Table 12

[0125]

[0126] Performance Test

[0127] The performance of the coatings prepared from Examples 1-8 and Comparative Examples 1-5 was determined, and the specific results are shown in Table 13:

[0128] Table 13 Performance of Coating Test

[0129]

[0130] *1: The sample is the same as Example 1, and the light curing time is extended from 5 min to 10 min;

[0131] *2: The sample is the same as Example 1, and after normal wet curing, it is placed at 200°C for 24 h;

[0132] *3: The sample is the same as Example 1, and after light curing, it is placed in an environment of 25°C and 25% relative humidity for 30 days.

[0133] (normal wet curing conditions: 25°C, 70% relative humidity, 30 days)

[0134] The determination method of each index is as follows:

[0135] 1. Glass transition temperature (Tg), the present application uses differential scanning calorimetry (DSC) to test the power difference (heat flow rate) and temperature relationship of the sample and the reference, and then obtains the glass transition temperature of the material, and the actual measurement is carried out according to GB / T19466.2-2004 / ISO 11357-2:1999 "Plastics-Differential Scanning Calorimetry (DSC)-Part 2: Determination of the Glass Transition Temperature".

[0136] 2. Coating hardness

[0137] It is divided into initial strength (after light irradiation) and late strength (30 days @ R.H 70%, 25°C)

[0138] The curing of the coating after light irradiation is basically a photocuring reaction, and the resin is not deeply crosslinked, and the hardness is not high. According to the actual situation, the hardness of the coating is ≥HB, and the workpiece coated or repaired can be packaged, transported or installed.

[0139] In the later use process, with the deepening of the moisture curing reaction of the resin, the crosslinking degree of the reaction increases, and the hardness of the coating increases. According to the summary of experimental data, under the condition of relative humidity R.H 70% and air temperature 25℃, after 30 days, the hardness of the coating increases to a certain degree and basically stabilizes, so 30 days@R.H 70%, 25℃ is selected as the test condition of the final hardness data of the coating.

[0140] The hardness of the coating is determined according to the national standard GB / T 6739-2006 "Pencil Test Method for Coating Film Hardness", but a Mitsubishi pencil is used as the hardness test pencil.

[0141] 3. Cathodic disbonding resistance

[0142] Test according to SY / T 0315-2005 (petroleum industry standard). The peeling diameter is ≤8mm.

[0143] 4. Flexibility

[0144] Determined according to GB / T 1731-2020 "Determination of Flexibility of Paint Film and Putty Film".

[0145] 5. Adhesion

[0146] Determined according to GB T 5210-2006 "Pull-off Method for Adhesion of Color Paint and Varnish".

[0147] 6. Impact resistance

[0148] Determined according to GB / T 1732-2020 "Determination of Impact Resistance of Paint Film".

[0149] 7. UV irradiation resistance

[0150] Determined according to GB / T 1865-2009 "Artificial Weathering and Artificial Radiation Exposure (Filtered Xenon Arc Radiation) for Color Paint and Varnish".

[0151] 8. Neutral salt spray resistance

[0152] Determined according to GB / T 1771-2007 "Determination of Neutral Salt Spray Resistance of Color Paint and Varnish", with a film thickness of 80±10μm.

[0153] 9. Temperature resistance

[0154] The present application relates to the temperature resistance of paint, which is measured by the adhesion of paint in practical use environment as a typical index, and the test condition is as follows:

[0155] The paint film thickness is 120±10 μm, and the paint is baked at 220℃ for 240h, and the adhesion is tested according to GB-T 5210-2006 "Color paint and varnish pull-off method adhesion test".

[0156] It can be seen from Table 13 that:

[0157] 1. Glass transition temperature Tg

[0158] The glass transition temperature of paint mainly depends on the degree of cross-linking reaction of photocuring and moisture curing, so the type of resin, curing conditions (photocuring time, intensity, moisture curing time and humidity, etc.) are important factors affecting the glass transition temperature. The molecular weight of E20 is large, the molecular chain is long and soft, so the Tg of Example 3 is relatively low; and Example 8 is cured in a low humidity environment, and the moisture curing cross-linking is poor, so the Tg is significantly lower than that of other samples; the Tg of Comparative Example 1 is also relatively low because the photocuring reaction promoting effect of the photoinitiator is poor; Example 7 has a higher Tg because of the additional post-heating baking, so the cross-linking reaction is more complete. Comparative Example 5 has the highest Tg because it contains the most polysilazane. In general, the glass transition temperature of the coating layer of the examples of the present application is relatively high, and the temperature resistance is good.

[0159] 2. Coating hardness

[0160] The initial coating hardness is ≥HB except that the hardness of Comparative Example 1 is B, because the initial hardness is mainly determined by the degree of photocuring reaction, and Comparative Example 1 uses PAG31102 iodonium salt as a photoinitiator, and the rest uses sulfonium salt photoinitiator. In the paint of the present application, the photocuring reaction promoting effect of iodonium salt photoinitiator is inferior to that of sulfonium salt. The hardness of Example 6 will also be higher because the photocuring time is doubled. Comparative Example 5 has the highest hardness of 4H because it contains the most polysilazane.

[0161] 3. Cathodic disbonding resistance

[0162] The cathodic disbonding resistance of Examples 1-7 is qualified (the disbonding diameter is ≤8mm), and the cathodic disbonding resistance of Example 8 is not good enough because the moisture curing effect is not ideal. The cathodic disbonding resistance of Comparative Example 1 is not good because the photocuring effect is not good, and the cathodic disbonding resistance of Comparative Examples 2-5 may be reduced because the resin variety changes after double curing of the coating layer.

[0163] 4. Flexibility

[0164] Examples 1-6 have good flexibility, among which Example 5 uses TTA26 cycloaliphatic epoxy resin with greater flexibility of molecular chain, so it has the best softness. Examples 2 and 8 using E51, DER332 and other epoxy resins with higher epoxy value have poorer flexibility. Example 7 has poor flexibility because of its high hardness.

[0165] Example 8 has poor wet curing crosslinking reaction, which affects its flexibility.

[0166] 5. Adhesion (pull-off method)

[0167] Overall, the adhesion of Examples 1-8 is relatively high, even if the wet curing reaction of Example 8 is not complete, it reaches 11.5 MPa, which can meet the requirements of most application environments. Comparative Example 1 has poor photocuring reaction, so its adhesion is relatively low.

[0168] 6. Impact resistance

[0169] The results of impact resistance are basically similar to the flexibility. Examples 1, 3, 4, 5, and 6 all have impact resistance of 50 kg·cm, while Example 2 contains E51, which has slightly greater brittleness, so its impact resistance is slightly poorer. Comparative Example 5 contains a large amount of polysilazane, so it has high hardness but poor impact resistance.

[0170] 7. Artificial weathering resistance

[0171] Examples 1-8 and Comparative Examples 1 and 4 have good artificial weathering resistance. The bisphenol A epoxy resin has poor weather resistance, but since the content of the cycloaliphatic epoxy resin in the coating is much higher, the overall weather resistance of the coating is excellent. Comparative Example 2 is slightly worse because the content of E44 resin is increased, which affects the weather resistance of the coating. Comparative Example 3 has high content of bisphenol A epoxy resin, so its weather resistance is very poor. Comparative Example 4 using pure cycloaliphatic epoxy resin has the best weather resistance.

[0172] 8. Salt spray resistance

[0173] Comparative Example 1 has poor photocuring, and Example 8 has poor wet curing, so their salt spray resistance is also relatively poor. The other cases have good salt spray resistance.

[0174] 9. Temperature resistance

[0175] The temperature resistance performance in the application takes the adhesion after baking at 200 DEG C for 240h in the actual application environment as a typical index to make a simple judgment. The paint film of Comparative Examples 3 and 5 cracks, indicating that the temperature resistance performance is poor. It may be because the crosslinking degree is too high, the paint film is too brittle, and the internal stress is high. The adhesion of other cases is improved, indicating that the temperature resistance performance is good. The introduction of polysilazane plays an important role in improving the temperature resistance performance, but the proportion is very important. Too high proportion will also cause the paint film to be too hard and brittle, and even crack.

[0176] The above only describes the preferred embodiments of the application, and it should be pointed out that for ordinary skilled persons in the art, several improvements and refinements can be made without departing from the principles of the application, and these improvements and refinements should also be considered within the protection scope of the application.

Claims

1. A light-moisture dual-cure epoxy polysilazane coating, characterized by, The raw materials include the following weight parts: alicyclic epoxy resin 10.0-35.0 parts, polysilazane modified epoxy resin 10.0-25.0 parts, dispersion wetting agent 0.3-1.0 parts, defoaming agent 0.1-0.5 parts, filler 5.0-20.0 parts, photoinitiator 1.0-5.0 parts, leveling agent 0.1-0.5 parts, rheological agent 0.1-0.8 parts and organic solvent 6.0-15.0 parts; The polysilazane modified epoxy resin is obtained by mixing the epoxy resin, solvent and polysilazane and performing reflux reaction; The mass ratio of the epoxy resin, solvent and polysilazane is (15-30):(20-40):(30-55); the epoxy resin is bisphenol A type epoxy resin, bisphenol F type epoxy resin or alicyclic epoxy resin.

2. The light-moisture dual cure epoxy polysilazane coating of claim 1, wherein, It also includes pigment 2.0-15.0 parts and anti-rust pigment 2.0-5.0 parts.

3. The light-moisture dual cure epoxy polysilazane coating of claim 1, wherein, The reflux reaction is performed at a temperature of 175-185℃ for 5.5-6.5h under N2 protection.

4. The light-moisture dual cure epoxy polysilazane coating of claim 1, wherein, The dispersion wetting agent is a polyhexamethylene adipate polyol-polyethyleneimine block copolymer type dispersant, an acrylate polymer type dispersant or a polyurethane or polyester type polymer dispersant.

5. The light-moisture dual cure epoxy polysilazane coating of claim 1, wherein, The photoinitiator is diazonium salt, triaryl sulfonium salt, alkyl sulfonium salt, iron arene salt or sulfonyloxy ketone.

6. The method of making the light-moisture dual cure epoxy polysilazane coating of claim 2, characterized in that, The method includes the following steps: 1) mixing the alicyclic epoxy resin and organic solvent uniformly, then adding the dispersion wetting agent and defoaming agent to obtain a first mixture; 2) adding the pigment, filler and anti-rust pigment to the first mixture, stirring uniformly, then performing grinding to obtain a grinding slurry; 3) conveying the grinding slurry to a paint mixing kettle with N2 protection, adding the photoinitiator, polysilazane modified epoxy resin, leveling agent and rheological agent, stirring uniformly, then filtering and packaging under N2 protection to obtain a light-humidity dual-cured epoxy polysilazane coating.

7. The method of using the light-moisture dual cure epoxy polysilazane coating according to any one of claims 1 to 5, characterized in that, The method includes the following steps: A. treating the surface of a workpiece to Sa2.5 or St3 and coating the coating on the surface of the workpiece; B. at normal temperature, waiting for the coating to naturally level for 5-10min, performing light irradiation for 2-5min in a 365nm ultraviolet light curing device, and the hardness reaches HB-H.

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