Iron oxide pigment with super weather resistance and corrosion resistance and preparation method thereof

Abstract

The invention discloses an iron oxide pigment with super weather resistance and corrosion resistance and a preparation method thereof, and relates to the technical field of weather-resistant and corrosion-resistant iron oxide pigments. The invention discloses an iron oxide pigment with super weather resistance and corrosion resistance. The iron oxide pigment is prepared from the following components in parts by mass: 100 parts of iron oxide, 1.5 to 3 parts of silane coupling agent, 2 to 4 parts of aluminum zirconate, 0.5 to 1.5 parts of weather-resistant antioxidant, 0.8 to 2 parts of molybdate corrosion inhibitor, 0.5 to 2 parts of nano silicon dioxide and 0.3 to 1 part of organic bentonite. Through an innovative composite formula and a preparation process, the stability of the iron oxide pigment in severe environments such as ultraviolet rays, damp heat and salt mist is greatly enhanced, excellent weather resistance and corrosion resistance are shown, the service life of the material can be effectively prolonged, and the maintenance cost can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of weather-resistant and corrosion-resistant iron oxide pigments, and specifically relates to an iron oxide pigment with super weather resistance and corrosion resistance and a preparation method thereof. BACKGROUND

[0002] Iron oxide pigments have been widely used in the fields of coatings, plastics, inks, and construction due to their bright colors, strong tinting strength, good light and heat resistance. However, with the continuous development of industrial technology and the increasing complexity of application scenarios, existing iron oxide pigments gradually reveal deficiencies in weather resistance and corrosion resistance.

[0003] In some harsh natural and industrial environments, such as coastal areas, chemical plant areas, and high-temperature and high-humidity areas, iron oxide pigments are easily eroded by ultraviolet light, oxygen, moisture, salt spray, and chemicals such as acids and bases, leading to problems such as color fading, coating peeling, and accelerated corrosion. These problems not only affect the appearance of the protected material, but also may reduce its service life, increase maintenance costs, and even cause safety hazards.

[0004] Traditional methods of preparing iron oxide pigments mainly focus on improving the purity and particle size distribution of the pigments through chemical synthesis or physical grinding, but have limited effect on improving their weather resistance and corrosion resistance. For example, simply increasing the purity or refining the particle size of iron oxide can improve the performance of the pigment to some extent, but cannot fundamentally solve the durability problem of the pigment in complex environments.

[0005] In addition, existing corrosion protection measures often rely on adding a large amount of corrosion inhibitor or using multiple layers of coating protection, which not only increases cost and process complexity, but also may cause environmental pollution. Especially under the background of increasingly stringent environmental protection requirements, traditional corrosion protection methods face many challenges.

[0006] Therefore, developing an iron oxide pigment with super weather resistance and corrosion resistance to meet the application requirements in complex environments has become a problem to be solved in the fields of material science and industrial application. SUMMARY

[0007] The present application aims to solve the problem of insufficient weather resistance and corrosion resistance of existing iron oxide pigments, and provides an iron oxide pigment with super weather resistance and corrosion resistance and a preparation method thereof. By adding silane coupling agent, aluminum zirconate, nano-silicon dioxide and other additives, and optimizing the preparation process, the stability of the iron oxide pigment in harsh environments such as ultraviolet light, salt spray, and acid and alkali is significantly improved, and its adhesion to the substrate and corrosion resistance are also enhanced, meeting the long-term use requirements in complex environments.

[0008] To achieve the above-mentioned purposes, the technical solution adopted by the present application is: The first subject matter protected by the present application is an iron oxide pigment with super weather resistance and corrosion resistance, comprising the following components in parts by mass: iron oxide 100 parts, silane coupling agent 1.5-3 parts, aluminum zirconate 2-4 parts, weather-resistant antioxidant 0.5-1.5 parts, molybdate corrosion inhibitor 0.8-2 parts, nano-silicon dioxide 0.5-2 parts, and organic bentonite 0.3-1 part; The weather-resistant antioxidant is a compound represented by Chemical Formula 1. Chemical Formula 1: ; R1 in Chemical Formula 1 is a substituent group, and R1 is selected from the group consisting of: phenyl, methyl, , hydroxyl, ; The substitution site.

[0009] Further, the weather-resistant antioxidant is a brand-new weather-resistant antioxidant.

[0010] Further, the particle size of the iron oxide is 0.1-0.5 μm.

[0011] Further, the silane coupling agent is any one of silane coupling agents KH-560 and KH-550.

[0012] Further, the molybdate corrosion inhibitor is sodium molybdate or zinc molybdate.

[0013] Further, the particle size of the nano-silicon dioxide is 10-20 nm.

[0014] Further, the weather-resistant antioxidant is any one of the compounds represented by the following structures: ; ; ; ; .

[0015] Further, the weather-resistant antioxidant exhibits fluorescence under ultraviolet light.

[0016] Further, the iron oxide pigment with super weather resistance and corrosion resistance exhibits fluorescence under ultraviolet light, and can be used as a security pigment.

[0017] The second subject matter protected by the present application is a preparation method of an iron oxide pigment with super weather resistance and corrosion resistance, comprising the following steps: (1) The iron oxide and organic bentonite are added to a mixing machine, and pre-dispersed at 500-800 r / min for 10-15 minutes to obtain material A; (2) the silane coupling agent is diluted with anhydrous ethanol to a 30% solution, sprayed into the material A, and reacted at 60-80°C for 30 minutes to obtain material B; (3) the aluminum zirconate, nano-silica and molybdate corrosion inhibitor are sequentially added to the material B, and dispersed at 1200-1500 r / min for 20 minutes under inert gas protection to obtain material C; (4) the weather-resistant antioxidant is added to the material C, mixed for 15 minutes, and then discharged, vacuum dried, and sieved to obtain the iron oxide pigment with super weather resistance and corrosion resistance.

[0018] Further, the spraying pressure in the step (2) is 0.2-0.4 MPa, and the atomized particle size is controlled to be 50-100 μm.

[0019] Further, the vacuum drying conditions in the step (4) are: temperature 40-60°C, vacuum degree -0.08~-0.1 MPa, and drying time 2-4 hours.

[0020] Further, the inert gas in the step (3) is nitrogen.

[0021] The third subject matter protected by the application is an ultraviolet anti-counterfeiting pigment containing the iron oxide pigment with super weather resistance and corrosion resistance.

[0022] The weather-resistant antioxidant in the application is a new type of hindered phenolic antioxidant. Its core mechanism is to actively capture free radicals and peroxide radicals caused by light, heat or oxygen by using phenolic hydroxyl groups as chain terminators. When the free radicals in the environment attack the pigment or coating, the phenolic hydroxyl groups of the antioxidant can preferentially provide hydrogen atoms (H•), and after the phenolic hydroxyl groups lose hydrogen atoms, they are converted into relatively stable and low-activity phenoxy radicals (ArO•). The phenoxy radicals are difficult to continue to participate in chain reactions or initiate new oxidation chains due to the steric hindrance effect of the adjacent bulky groups. In this way, the attacking free radicals are quenched, and the chain reaction of oxidative degradation is interrupted, thereby protecting the iron oxide pigment and the coating matrix from oxidative damage. The weather-resistant antioxidant contains a conjugated system, which produces fluorescence. When the weather-resistant antioxidant absorbs ultraviolet light energy, it releases energy in the form of fluorescence, which is a physical quenching method of ultraviolet energy, reducing the opportunity for ultraviolet light to directly initiate oxidation reactions or degrade the polymer matrix. This provides an additional protective layer for its weather resistance.

[0023] The iron oxide pigment formula with super weather resistance and corrosion resistance of the application solves the performance problem in harsh environment through the multidimensional synergistic effect of iron oxide, nano silicon dioxide, organic bentonite, aluminum zirconate, molybdate corrosion inhibitor, weather-resistant antioxidant and silane coupling agent. In the physical shielding dimension, nano silicon dioxide fills the gap between pigment particles to form a dense barrier to block water vapor and ion penetration, and organic bentonite thickens by thixotropy to improve the density of the coating and reduce capillary channels; in the chemical passivation dimension, aluminum zirconate forms a passivation film on the metal substrate to inhibit corrosion, and the molybdate corrosion inhibitor has corrosion inhibition effect; for ultraviolet degradation, the weather-resistant antioxidant implements chemical quenching to capture free radicals and terminate the oxidation chain reaction, and through physical quenching, it converts ultraviolet light into visible light by using the fluorescence characteristic; the silane coupling agent bridges the inorganic pigment and the organic resin to strengthen the interface bonding. The key synergistic mechanism is that the silane coupling agent is condensed with the surface hydroxyl group of nano SiO2 after hydrolysis to form an organic-inorganic hybrid network, which enhances the dispersibility and blocks the corrosion medium; the physical shielding layer of aluminum zirconate and the molybdate together form a passivation film to synergistically inhibit electrochemical corrosion; the weather-resistant antioxidant removes free radicals while nano SiO2 scatters / absorbs ultraviolet light to reduce its consumption. The preparation process further strengthens the effect: the spray coating process ensures that the silane is uniformly coated on the iron oxide, the inert gas protection dispersion prevents the oxidation of active components, and the low-temperature vacuum drying retains the ultraviolet fluorescence characteristics of the antioxidant.

[0024] Compared with the prior art, the application has the following advantages: 1. Significant improvement in weather resistance and corrosion resistance: The innovative composite formula and preparation process of the application greatly enhance the stability of iron oxide pigment in harsh environments such as ultraviolet light, heat and humidity, salt spray, etc., and exhibit excellent weather resistance and corrosion resistance, effectively extending the service life of the material and reducing maintenance costs.

[0025] 2. Enhanced coating adhesion and density: The synergistic effect of added components such as silane coupling agent, nano silicon dioxide, organic bentonite, etc. significantly improves the adhesion of pigment to substrate and the density of coating, effectively blocking the penetration of external corrosive media and further strengthening the protective effect.

[0026] 3. Improved environmental performance: The application reduces the dependence on traditional large amounts of corrosion inhibitors, reduces the potential pollution to the environment, and realizes efficient use of resources through optimized process, meeting the increasingly stringent environmental requirements. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The nuclear magnetic resonance spectrum of the weather-resistant antioxidant 1 described in the application. DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present application.

[0029] Example 1-1: Synthesis of weather-resistant antioxidant 1: .

[0030] Under the protection of nitrogen, 15 g of raw material 1, 10.62 g of raw material 2, 22.00 g of potassium phosphate trihydrate and 200 ml of DMSO were sequentially added into the reaction system, and after being stirred uniformly, 0.05 g of pyridine-2-carboxylic acid and 0.4 g of CuI were added under the protection of nitrogen, and heated at 80℃ for 14 h; after cooling, the reaction mixture was extracted with an ammonia solution and methyl tert-butyl ether, the organic phase was washed with water five times, the combined organic phase was dried with anhydrous magnesium sulfate, filtered, rotary evaporated, and subjected to silica gel column chromatography with a mixture of n-heptane and ethyl acetate as the eluent to obtain 17.78 g of intermediate 1.

[0031] Under the protection of nitrogen, 17.78 g of intermediate 1, 23.03 g of raw material 3, 8.03 g of triethylenediamine and 250 ml of methanol were sequentially added into the reaction system, and heated at 70℃ for 8 h; after the reaction was completed, the solvent was rotary evaporated, 100 ml of toluene was added into the dry powder after rotary evaporation, heated to 95℃, stirred for 1 h, then cooled in a refrigerator at 0℃ for 3 h, filtered, and the filter cake was dried and subjected to silica gel column chromatography with a mixture of n-heptane and ethyl acetate as the eluent to obtain 29.27 g of weather-resistant antioxidant 1.

[0032] Structure identification: Mass spectrum M / Z (MS+H + ) of intermediate 1: 497; Mass spectrum M / Z (MS+H + ) of weather-resistant antioxidant 1: 1017; Weather-resistant antioxidant 1 1H NMR (Chloroform-d) δ 9.02 (s, 2H), 8.38 (d, 1H), 8.22 (d, 1H), 8.13 (d, 1H), 7.83 (dd, 1H), 7.68-7.54 (m, 7H), 7.50-7.33 (m, 7H), 7.29 (dd, 1H), 6.95 (t, 4H), 6.32 (p, 1H), 4.72 (s, 2H), 2.85 (m, 4H), 2.76-2.60 (m, 4H), 1.70-1.65 (m, 9H), 1.57-1.51 (m, 9H), 1.45-1.39 (m, 9H), 1.38-1.33 (m, 9H).

[0033] Examples 1-2 to 1-5: Examples 1-2 to 1-5 were prepared in turn, replacing raw material 1 in Example 1-1, and the rest remained the same. The specific structure of raw material 1, weather-resistant antioxidant 2 to weather-resistant antioxidant 5, and structure identification data are shown in Table 1.

[0034] Table 1 Example 2: Preparation of an iron oxide pigment with super weather resistance and corrosion resistance: 1. Mass ratio of raw materials: Iron oxide: 100 parts, average particle size 0.3 μm, purchased from Shanghai Yinn Chemical Technology Co., Ltd.; Silane coupling agent: 2 parts, selected from silane coupling agent KH-560, purchased from Shanghai Mayreer Biochemical Technology Co., Ltd.; Aluminum zirconate: 3 parts, purchased from Shaanxi Xihua Chemical Industry Co., Ltd.; Weather-resistant antioxidant: 1 part, selected from weather-resistant antioxidant 1 synthesized in Example 1-1; Molybdate corrosion inhibitor: 1.5 parts, selected from sodium molybdate, purchased from Tianjin Hainachuan Science and Technology Development Co., Ltd.; Nano-silicon dioxide: 1 part, average particle size 15 nm, purchased from Shandong Xiya Chemical Co., Ltd.; Organic bentonite: 0.5 parts, purchased from Shanghai Baoyangbaoxin Biological Technology Co., Ltd.

[0035] 2. Preparation method: (1) 100 parts of iron oxide and 0.5 parts of organic bentonite were added into a high-speed mixer, the mixer was started, and pre-dispersion was carried out at a speed of 600 r / min for 12 minutes to ensure uniform mixing of the materials without caking. After dispersion, material A was obtained in the form of uniform red powder; (2) 2 parts of silane coupling agent KH-560 were diluted with anhydrous ethanol to form a solution with a mass concentration of 30%, and the solution was sprayed into material A using a high-pressure spraying system (the spraying pressure was set to 0.3 MPa). The spraying atomization particle size was controlled within 75 μm, and the mixture was heated to 70°C during spraying, and the reaction was continued at this temperature for 30 minutes. After the reaction was completed, material B was obtained, which had a uniform silane coating on the surface and no obvious agglomeration. (3) 3 parts of aluminum zirconate, 1 part of nano-silicon dioxide, and 1.5 parts of sodium molybdate corrosion inhibitor were sequentially added to material B, and the mixture was transferred to a sealed disperser. Under the protection of nitrogen inert gas (the flow rate was set to 5 L / min), high-speed dispersion was carried out at a speed of 1350 r / min for 20 minutes. During dispersion, it was ensured that the components were fully mixed to form a dense composite structure. After completion, material C was obtained. (4) 1 part of weather-resistant antioxidant 1 was added to material C, and mixed at a speed of 500 r / min for 15 minutes to ensure uniform distribution of the antioxidant. Subsequently, the mixture was placed in a vacuum drying oven, and the drying conditions were set as follows: temperature 50°C, vacuum degree -0.09 MPa, and drying time 3 hours. After drying, the material was sieved through an 80-mesh screen to obtain the final product: an iron oxide pigment with super weather resistance and corrosion resistance.

[0036] Examples 3 to 6: An iron oxide pigment with super weather resistance and corrosion resistance was prepared according to the preparation method of Example 2, except that weather-resistant antioxidant 1 was replaced by weather-resistant antioxidants 2-5, and the rest remained the same as in Example 2.

[0037] Comparative Example 1: An iron oxide pigment with super weather resistance and corrosion resistance was prepared according to the preparation method of Example 2, except that weather-resistant antioxidant 1 was replaced by hindered phenolic antioxidant BHT, and the rest remained the same as in Example 2.

[0038] The structure of hindered phenolic antioxidant BHT is: CAS No.: 128-37-0.

[0039] Comparative Example 2: An iron oxide pigment with super weather resistance and corrosion resistance was prepared according to the preparation method of Example 2, except that weather-resistant antioxidant 1 was replaced by YFK-1024, and the rest remained the same as in Example 2.

[0040] The structure of YFK-1024 is: , and the CAS number is: 32687-78-8.

[0041] Comparative Example 3: A preparation of an iron oxide pigment with super weather resistance and corrosion resistance, referring to the preparation method of Example 2, replacing the weather-resistant antioxidant 1 therein with , and the rest remains the same as Example 2.

[0042] Comparative Example 4: A preparation of an iron oxide pigment with super weather resistance and corrosion resistance, referring to the preparation method of Example 2, replacing the weather-resistant antioxidant 1 therein with , and the rest remains the same as Example 2.

[0043] Comparative Example 5: A preparation of an iron oxide pigment with super weather resistance and corrosion resistance, referring to the preparation method of Example 2, without adding the weather-resistant antioxidant 1 therein, and the rest remains the same as Example 2.

[0044] Comparative Example 6: A preparation of an iron oxide pigment with super weather resistance and corrosion resistance, referring to the preparation method of Example 2, without adding the aluminum zirconate therein, and the rest remains the same as Example 2.

[0045] Comparative Example 7: A preparation of an iron oxide pigment with super weather resistance and corrosion resistance, referring to the preparation method of Example 2, without adding the molybdate corrosion inhibitor therein, and the rest remains the same as Example 2.

[0046] Comparative Example 8: A preparation of an iron oxide pigment with super weather resistance and corrosion resistance, referring to the preparation method of Example 2, without adding the nano-silicon dioxide therein, and the rest remains the same as Example 2.

[0047] Comparative Example 9: A preparation of an iron oxide pigment with super weather resistance and corrosion resistance, referring to the preparation method of Example 2, without adding the silane coupling agent therein, and the rest remains the same as Example 2.

[0048] Performance test: All samples were prepared into standard paint coatings (thickness 50 μm) and coated on Q235 carbon steel substrates. After curing in a constant temperature and humidity chamber (25°C, 60% RH) for 24 hours, the test was carried out, and the color difference instrument was used for measurement.

[0049] 1. Ultraviolet aging test: the sample was exposed to UV-B lamp (wavelength 313 nm, irradiance 0.76 W / m 2Color change (ΔΕ) was measured by color difference meter after 1000 hours of exposure, and the data is shown in Table 2.

[0050] 2. Humidity and heat aging test: the sample was placed in an environment of 90% RH and 60°C for 7 days, then in an environment of 60% RH and 40°C for 7 days, and finally in an environment of 40% RH and 30°C for 7 days. Color change (ΔΕ) was measured by color difference meter, and the data is shown in Table 2.

[0051] 3. Salt corrosion aging test: the sample was placed in a 5% NaCl salt spray chamber at a temperature of 35°C for 100 hours. Color change (ΔΕ) was measured by color difference meter, and the data is shown in Table 2.

[0052] The calculation formula of color change ΔE is: ; Wherein: ΔL* is the difference in brightness between the standard color plate and the sample; Δa* is the difference in red-green axis between the standard color plate and the sample; and Δb* is the difference in yellow-blue axis between the standard color plate and the sample.

[0053] Table 2 In the performance test data of Table 2, the overall trend shows that the examples exhibit significantly superior performance stability in all aging tests, while the performance of the comparative examples (i.e., formulations modified or missing key components) is significantly degraded. Specifically, in the ultraviolet aging, humidity and heat aging, and salt corrosion aging tests, the color difference change (ΔΕ) of the examples is maintained at a low level, while the ΔΕ values of the comparative examples are generally higher, especially when the core components such as weather-resistant antioxidant, aluminum zirconate, acid salt corrosion inhibitor, nano-silicon dioxide, or silane coupling agent are missing in the formulation, the performance degradation is most significant. For example, after replacing the traditional antioxidant (such as BHT or YFK-1024) or removing any functional additive in the comparative example, the ΔE value rises sharply, indicating that it cannot effectively maintain color stability in harsh environments.

[0054] The weather-resistant antioxidant resists photodegradation through both chemical quenching (capturing free radicals to terminate oxidation chain reactions) and physical quenching (fluorescent properties converting ultraviolet energy); the aluminum zirconate and molybdate corrosion inhibitor cooperatively forms a chemical passivation film to inhibit electrochemical corrosion; the nano-silicon dioxide and organic bentonite provide physical shielding to block water vapor and ion penetration; and the silane coupling agent strengthens the interface bonding between the pigment and the substrate, improving the overall density. The comparative examples disrupt this synergistic system - such as removing the weather-resistant antioxidant leading to increased free radical attack, or missing the aluminum zirconate weakening the passivation protection - ultimately resulting in a comprehensive decline in weather resistance and corrosion resistance. Therefore, the component optimization and synergistic effect of the present application is the key to achieving super-weather resistance and corrosion resistance in complex environments.

[0055] While embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and variations can be made to these embodiments without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An iron oxide pigment having super weather resistance and anticorrosive properties, characterized in that, The composition comprises the following components by mass fraction: iron oxide 100 parts, silane coupling agent 1.5-3 parts, aluminum zirconate 2-4 parts, weather-resistant antioxidant 0.5-1.5 parts, molybdate corrosion inhibitor 0.8-2 parts, nano-silicon dioxide 0.5-2 parts, organic bentonite 0.3-1 part; The weather-resistant antioxidant is a compound represented by Chemical Formula 1. Chemical Formula 1: ; R1in the chemical formula 1 is a substituent, and R1is selected from the group consisting of a phenyl group, a methyl group, a hydroxyl group, ; The substitution site.

2. The iron oxide pigment having super weather resistance and corrosion resistance according to claim 1, characterized in that, The particle size of the iron oxide is 0.1-0.5 μm.

3. The iron oxide pigment with super weather resistance and corrosion resistance according to claim 1, characterized in that: The silane coupling agent is any one of silane coupling agents KH-560 and KH-550.

4. The iron oxide pigment having super weather resistance and corrosion resistance according to claim 1, characterized in that, The molybdate corrosion inhibitor is sodium molybdate or zinc molybdate.

5. The iron oxide pigment having super weather resistance and corrosion resistance according to claim 1, characterized in that, The particle size of the nano-silicon dioxide is 10-20 nm.

6. The iron oxide pigment having super weather resistance and corrosion resistance according to claim 1, characterized in that, The weather-resistant antioxidant is any one of compounds represented by the following structures: ； ； ； ； 。 7. The iron oxide pigment having super weather resistance and corrosion resistance according to claim 1, characterized in that, The weather-resistant antioxidant exhibits fluorescence under ultraviolet light.

8. A process for the preparation of an iron oxide pigment having super weathering and anticorrosive properties according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: (1) The iron oxide and organic bentonite are added to a mixing machine, pre-dispersed at 500-800 r / min for 10-15 minutes to obtain material A; (2) The silane coupling agent is diluted with anhydrous ethanol to a 30% solution, sprayed into the material A, and heated to 60-80°C for reaction for 30 minutes to obtain material B; (3) The aluminum zirconate, nano-silicon dioxide and molybdate corrosion inhibitor are sequentially added to the material B, dispersed at 1200-1500 r / min under inert gas protection for 20 minutes to obtain material C; (4) The weather-resistant antioxidant is added to the material C, mixed for 15 minutes, discharged, vacuum dried, and sieved to obtain an iron oxide pigment with super weather resistance and corrosion resistance.

9. The method of claim 8, wherein the iron oxide pigment having super weather resistance and corrosion resistance is prepared by adding 0.1 to 1 wt% of the compound of formula (1) to the mixture of the iron oxide pigment and the dispersant, and then mixing the mixture. The spraying pressure in step (2) is 0.2-0.4 MPa, and the atomized particle size is controlled to be 50-100 μm.

10. The method of claim 8, wherein the iron oxide pigment having super weather resistance and corrosion resistance is prepared by adding 0.1 to 1 wt% of the dispersant to 100 parts by weight of the iron oxide pigment, and then adding 0.1 to 1 wt% of the dispersant to the mixture. The vacuum drying conditions in step (4) are: temperature 40-60°C, vacuum degree -0.08~-0.1 MPa, and drying time 2-4 hours.

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