Flexible polar coating compositions, coating materials, their preparation methods and applications

Abstract

This invention discloses a flexible polar coating composition, coating material, its preparation method, and its application. The flexible polar coating composition comprises a first component and a second component. The first component includes SER-modified resin, pigments, fillers, additives, and a solvent. The second component includes a polyamide resin and a solvent. The SER-modified resin is prepared by first reacting bisphenol A type epoxy resin with 3-isocyanate-propyltrimethoxysilane in a pre-addition reaction to obtain a Sil-EP modified resin, and then reacting it with hydroxyl-terminated polydimethylsilane in an addition reaction. The flexible polar coating composition and coating material provided by this invention exhibit excellent adhesion, flexibility, and resistance to alternating high and low temperatures under polar temperature (-60℃) conditions. It can effectively prevent paint film damage and peeling on steel structure surfaces caused by mechanical impact and temperature changes in low-temperature environments, thereby improving the corrosion protection life of the coating material on steel structure surfaces in polar environments.

Description

Technical Field

[0001] This invention relates to a coating material, specifically to a flexible polar coating composition, coating material, its preparation method and application, belonging to the field of heavy-duty anti-corrosion coating technology. Background Technology

[0002] The Arctic region is extremely cold, especially in the polar areas within the Arctic Circle, where winter temperatures can drop to -50 degrees Celsius or even lower. In such low-temperature environments, coatings on steel substrates often lose their toughness. When the substrate is impacted or deformed due to alternating temperatures, the coating film may crack or peel off due to loss of adhesion, thus failing to provide corrosion protection to the steel substrate. Therefore, coating toughness in low-temperature environments has always been a crucial research challenge in the coatings industry. Typically, when temperatures drop below -20°C, conventional epoxy coatings begin to exhibit poor adhesion and reduced impact resistance. To address this issue, the industry usually reduces coating crosslinking density and adds toughening resins to improve coating toughness, but this approach simultaneously reduces the environmental resistance of the paint film. In recent years, both domestic and international efforts to develop the Arctic region have increased, resulting in the development of equipment for icebreakers and high-altitude, frigid regions. However, these efforts have failed to achieve a balance between toughness and environmental resistance, yielding unsatisfactory results. Therefore, developing a flexible polar coating material with greater toughness and environmental resistance is of great significance for improving my country's infrastructure and development capabilities in the Arctic region. Summary of the Invention

[0003] The main objective of this invention is to provide a flexible polar coating composition, coating material and preparation method thereof, so as to overcome the shortcomings of the prior art.

[0004] Another object of the present invention is to provide the application of the aforementioned flexible polar coating composition and coating material.

[0005] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0006] This invention provides a flexible polar coating composition, comprising: a first component and a second component, wherein the first component comprises SER-modified resin, pigments, fillers, additives and solvent, and the second component comprises polyamide resin and solvent;

[0007] The SER modified resin is prepared by first performing a pre-addition reaction between bisphenol A type epoxy resin and 3-isocyanate-propyltrimethoxysilane to obtain Sil-EP modified resin, and then performing an addition reaction between the Sil-EP modified resin and hydroxyl-terminated polydimethylsilane.

[0008] In some embodiments, the first component comprises the following components in parts by weight: 45-55 parts of SER modified resin, 20-30 parts of pigments and fillers, 1-2 parts of additives, and 20-25 parts of solvent.

[0009] In some embodiments, the second component comprises the following components in parts by weight: 15-25 parts of polyamide resin and 75-85 parts of solvent.

[0010] This invention also provides a method for preparing the aforementioned flexible polar coating composition, comprising:

[0011] First, bisphenol A type epoxy resin is pre-added to 3-isocyanate-propyltrimethoxysilane to obtain Sil-EP modified resin. Then, Sil-EP modified resin is added to hydroxyl-terminated polydimethylsilane to obtain SER modified resin.

[0012] The SER-modified resin, pigments, fillers, additives, and solvent are mixed evenly to obtain the first component;

[0013] The polyamide resin and solvent are mixed evenly to obtain the second component;

[0014] The first component and the second component are mixed evenly to obtain the flexible polar coating composition.

[0015] The present invention also provides a flexible polar coating material, which is formed from the aforementioned flexible polar coating composition.

[0016] This invention also provides the application of the aforementioned flexible polar coating composition or flexible polar coating material in steel coating protection in polar environments.

[0017] Accordingly, embodiments of the present invention also provide a method for protecting the surface of a steel substrate in a polar environment, comprising: coating the flexible polar coating composition onto the surface of the steel substrate to form a protective coating.

[0018] Compared with the prior art, the beneficial effects of the present invention include:

[0019] The flexible polar coating composition and coating material provided by this invention, due to the aforementioned raw material component design, possess excellent low-temperature adhesion, low-temperature impact resistance, low-temperature flexibility, resistance to thermal cycling, and salt water resistance. For example, when the coating material is tested for adhesion, impact resistance, and flexibility at -60℃, the adhesion still reaches 12MPa, and it can pass the 10 Joule impact test, with a flexibility of up to 1mm. After 30 cycles of thermal cycling between -60℃ and 80℃, the paint film remains in good condition, with an adhesion exceeding 10MPa. After 2000 hours of salt water resistance testing following thermal cycling, the paint film shows no rust, cracking, or peeling. When applied to steel structure surfaces, this coating material effectively prevents paint film damage and peeling caused by mechanical impact and temperature changes in low-temperature environments, thereby improving the corrosion protection life of the coating material on steel structure surfaces in polar environments. Furthermore, it is easy to prepare and suitable for large-scale production and application. Detailed Implementation

[0020] In view of the problems existing in the prior art, the inventors of this invention have conducted extensive and in-depth research and have provided a flexible polar coating composition and coating material designed with specific raw material components, which has excellent low-temperature adhesion, low-temperature impact resistance, low-temperature flexibility, resistance to thermal cycling, and salt water resistance.

[0021] The following will provide a further explanation of the technical solution, its implementation process, and its principles.

[0022] As one aspect of the technical solution of the present invention, a flexible polar coating composition includes a first component and a second component. The first component includes Silane-Epoxy-Rubber modified resin (hereinafter referred to as SER modified resin), pigments, fillers, additives and solvents, etc., and the second component includes polyamide resin and solvent.

[0023] In some embodiments, the SER modified resin is prepared by first performing a pre-addition reaction between bisphenol A type epoxy resin and 3-isocyanate-propyltrimethoxysilane to obtain Silane-Epoxy resin (which can be simply referred to as Sil-EP modified resin), and then performing an addition reaction between the Sil-EP modified resin and hydroxyl-terminated polydimethylsilane.

[0024] In some embodiments, the bisphenol A type epoxy resin used in the preparation of the SER modified resin has a weight-average molecular weight of 900-1120 and an epoxy equivalent of 450-560.

[0025] In some embodiments, the 3-isocyanate-propyltrimethoxysilane used in the preparation of the SER modified resin has a weight-average molecular weight of 200-230 and an NCO equivalent of 200-230.

[0026] In some embodiments, the mass ratio of the bisphenol A type epoxy resin to 3-isocyanate-propyltrimethoxysilane is 3.0 to 3.3:1.

[0027] In some embodiments, the hydroxyl-terminated polydimethylsilane has a weight-average molecular weight of 41,000 to 52,000 and a viscosity of 3,500 to 4,500 CPS.

[0028] In some embodiments, the mass ratio of the Sil-EP modified resin to the hydroxyl-terminated polydimethylsilane is 1:12.5 to 13.4.

[0029] In some preferred embodiments, the SER modified resin is prepared by pre-addition reaction of bisphenol A type epoxy resin and 3-isocyanate-propyltrimethoxysilane at a mass ratio of 3.0 to 3.3:1, followed by reaction of the product with hydroxyl-terminated polydimethylsilane at a mass ratio of 1:12.5 to 13.4.

[0030] In some more preferred embodiments, the SER-modified resin is prepared by pre-addition reaction of bisphenol A type epoxy resin with a weight average molecular weight of 900-1120 and an epoxy equivalent of 450-560 with 3-isocyanate-propyltrimethoxysilane with a weight average molecular weight of 200-230 and an NCO equivalent of 200-230 at a mass ratio of 3.0-3.3:1 to obtain Silane-Epoxy resin (Sil-EP modified resin), and then by addition reaction of Sil-EP modified resin with hydroxyl-terminated polydimethylsilane with a weight average molecular weight of 41000-52000 and a viscosity of 3500-4500 CPS at a mass ratio of 1:12.5-13.4.

[0031] In some embodiments, the first component comprises the following components in parts by weight: 45-55 parts of SER modified resin, 20-30 parts of pigments and fillers, 1-2 parts of additives, and 20-25 parts of solvent.

[0032] In some embodiments, the second component comprises the following components in parts by weight: 15-25 parts of polyamide resin and 75-85 parts of solvent.

[0033] In some embodiments, the mass ratio of the first component to the second component is 10.2 to 12.8:1.

[0034] In some embodiments, the active hydrogen equivalent of the polyamide resin is 275 to 285.

[0035] Furthermore, the pigments and fillers include any one or more combinations of titanium dioxide, iron oxide black, iron oxide red, talc, and silica powder, and are not limited thereto.

[0036] Furthermore, the additives include any one or more combinations of defoamers, leveling agents, and rheology modifiers, and are not limited thereto.

[0037] Furthermore, the solvent includes, but is not limited to, any one or more combinations of xylene, propylene glycol methyl ether (PM), methyl isobutyl ketone (MIBK), acetone, n-butanol, and acetylacetone.

[0038] As another aspect of the technical solution of the present invention, a method for preparing a flexible polar coating composition includes:

[0039] First, bisphenol A type epoxy resin is pre-added to 3-isocyanate-propyltrimethoxysilane to obtain Sil-EP modified resin. Then, Sil-EP modified resin is added to hydroxyl-terminated polydimethylsilane to obtain SER modified resin.

[0040] The SER-modified resin, pigments, fillers, additives, and solvent are mixed evenly to obtain the first component;

[0041] The polyamide resin and solvent are mixed evenly to obtain the second component;

[0042] The first component and the second component are mixed evenly to obtain the flexible polar coating composition.

[0043] In some embodiments, the preparation process of the SER-modified resin includes:

[0044] Bisphenol A type epoxy resin was added to a mixed solvent containing xylene and butanol and heated to 55-65°C to dissolve it completely. Then, 3-isocyanate-propyltrimethoxysilane was added in batches until the mass ratio of bisphenol A type epoxy resin to 3-isocyanate-propyltrimethoxysilane was 3.0-3.3:1. The pre-addition reaction was then carried out at 55-65°C for 2-2.5 hours under stirring to obtain Sil-EP modified resin.

[0045] Hydroxyl-terminated polydimethylsilane was added in batches under stirring until the mass ratio of Sil-EP modified resin to hydroxyl-terminated polydimethylsilane was 1:12.5-13.4. Then, an addition reaction was carried out at 55-65°C for 1-1.5 h under stirring to obtain the SER modified resin.

[0046] The bisphenol A type epoxy resin, 3-isocyanate-propyltrimethoxysilane, and hydroxyl-terminated polydimethylsilane used in the preparation of the SER modified resin are as previously defined and will not be repeated here.

[0047] In some more specific embodiments, during the preparation of the SER modified resin, an excess of epoxy is used. To ensure the stable distribution of the coupling agent in the epoxy structure, the mass ratio of bisphenol A type epoxy resin to 3-isocyanate-propyltrimethoxysilane is set to 3.0 to 3.3:1.

[0048] Furthermore, the present invention sets the mass ratio of Sil-EP modified resin to hydroxyl-terminated polydimethylsilane to 1:12.5-13.4, which can prevent the self-polymerization of hydroxyl-terminated polydimethylsilane. In addition, the Sil-EP modified resin is used to sandwich the hydroxyl-terminated polydimethylsilane in the middle to eliminate the silanol groups on the hydroxyl-terminated polydimethylsilane, thereby ensuring its stability.

[0049] This invention introduces a silane structure into an epoxy structure by reacting the hydroxyl groups in the epoxy structure with a silane coupling agent (3-isocyanate-propyltrimethoxysilane) containing NCO groups, without destroying the epoxy groups. Then, a terminal hydroxyl polydimethylsilane with silanol groups at both ends is crosslinked with silanol groups and incorporated into the structure.

[0050] As one more specific embodiment, the preparation method of the flexible polar coating composition may include the following steps:

[0051] A mixed solvent of xylene and butanol was added to a reaction vessel. Bisphenol A type epoxy resin was added under low-speed stirring, and the temperature was raised to 55-65°C. The mixture was stirred at low speed until the epoxy resin was fully dissolved. Then, 3-isocyanate-propyltrimethoxysilane was added in batches until the mass ratio of bisphenol A type epoxy resin to 3-isocyanate-propyltrimethoxysilane was 3.0-3.3:1. The pre-addition reaction was carried out at 55-65°C for 2-2.5 hours under stirring to obtain a pre-addition resin. Then, while maintaining stirring, hydroxyl-terminated polydimethylsilane was added in batches until the mass ratio of pre-addition resin to hydroxyl-terminated polydimethylsilane was 1:12.5-13.4. The reaction was carried out at 55-65°C for 1-1.5 hours under stirring. After cooling to room temperature, SER modified resin was obtained.

[0052] The SER-modified resin was mixed evenly with pigments, fillers, additives, and solvents to obtain the first component;

[0053] The polyamide resin and solvent are mixed evenly to obtain the second component.

[0054] For example, a mixed solvent of xylene and butanol can be added to a reaction vessel, and the stirrer can be turned on to stir at a speed of 300-500 r / min. Then, bisphenol A type epoxy resin is added and heated to 55-65°C. Then, under stirring, 3-isocyanate-propyltrimethoxysilane is slowly added dropwise to the bisphenol A type epoxy resin solution at a mass ratio of 3.0-3.3:1. The mixture is stirred continuously and the temperature is controlled at 55-65°C for a pre-addition reaction for 2-2.5 h to obtain a pre-addition resin (Sil-EP modified resin). Then, while maintaining stirring, hydroxyl-terminated polydimethylsilane is slowly added to the Sil-EP modified resin at a mass ratio of 1:12.5-13.4. The mixture is then reacted at 55-65°C for 1-1.5 h under stirring to obtain a SER modified resin.

[0055] The mechanism for preparing SER-modified resin according to the present invention is as follows: Bisphenol A type epoxy resin is reacted with 3-isocyanate-propyltrimethoxysilane. The bisphenol A type epoxy resin has an epoxy equivalent of 450-560 and its molecular structure contains at least two hydroxyl groups. These hydroxyl groups can undergo an addition reaction with the NCO groups in 3-isocyanate-propyltrimethoxysilane, thereby introducing propyltrimethoxysilane into the epoxy resin structure without consuming epoxy groups, forming a Sil-EP modified resin. Subsequently, through a condensation reaction between silanol groups and silyl alkoxy groups, the sil-EP modified resin reacts to remove the silanol groups at both ends of the terminal hydroxyl polydimethylsilane, incorporating them into the Sil-EP modified resin structure to generate the SER modified resin.

[0056] The resin structure is characterized by: retaining the toughness of hydroxyl-terminated polydimethylsilane while eliminating silanol groups to improve its storage stability and prevent over-polymerization from affecting the coating's adhesion; the presence of epoxy groups allows for further reaction with polyamide resin, generating a three-dimensional network coating structure to ensure environmental resistance; and the retention of some silanyl alkoxy groups, which continue to slowly hydrolyze to release silanol groups after the epoxy and active hydrogen crosslink to form a film, further crosslinking with hydroxyl groups on the metal substrate to improve coating adhesion. The long-chain silanes in the SER resin structure impart good elongation and tensile strength to the coating film, and the structure is insensitive to temperature changes, preventing increased brittleness with rapid temperature decreases. Therefore, it exhibits excellent low-temperature toughness, ensuring good flexibility even in low-temperature environments, preventing cracking or peeling due to brittleness.

[0057] In some embodiments, the preparation method specifically includes: mixing the SER modified resin with pigments, fillers, additives and a portion of solvent in sequence until uniform, then dispersing it at a speed of 2000-3000 r / min for 25-30 min, and then adjusting the viscosity of the obtained mixture to 120-130 KU with another portion of solvent to obtain the first component.

[0058] In some embodiments, the preparation method specifically includes: uniformly mixing polyamide resin and solvent under low-speed stirring conditions of 300-500 r / min to obtain a second component. The second component of this invention is an amine component, responsible for crosslinking with the epoxy in the first component.

[0059] In one embodiment, the preparation method further includes: mixing the first component and the second component uniformly at a mass ratio of 10.2 to 12.8:1. The SER-modified resin structure prepared by the present invention can increase the elongation of the coating film, thereby improving the adaptability of the coating film under alternating hot and cold conditions; while the normal crosslinking of epoxy and amine can ensure the basic shielding performance and seawater and chemical resistance of the coating film.

[0060] Another aspect of the present invention provides a flexible polar coating material formed from the aforementioned flexible polar coating composition (also referred to as a coating composition for forming a flexible polar coating material).

[0061] Furthermore, the dry film thickness of the flexible polar coating material is within 200 μm.

[0062] Another aspect of the present invention provides the application of the aforementioned flexible polar coating composition or flexible polar coating material in the field of steel substrate surface protection in polar environments.

[0063] For example, one embodiment of the present invention provides a method for protecting the surface of a steel substrate in a polar environment, comprising: coating the composition for forming a flexible polar coating material onto the surface of a steel substrate to form a protective coating.

[0064] Accordingly, another aspect of the present invention provides a method for protecting the surface of a steel substrate in a polar environment, comprising: coating the flexible polar coating composition onto the surface of the steel substrate to form a protective coating.

[0065] In summary, the flexible polar coating material provided by this invention possesses excellent low-temperature adhesion, low-temperature impact resistance, low-temperature flexibility, resistance to thermal cycling, and salt water resistance. For example, when tested for adhesion, impact resistance, and flexibility at -60℃, the coating material still exhibits an adhesion of 12MPa, passes a 10 Joule impact test, and achieves a flexibility of 1mm. After 30 cycles of thermal cycling between -60℃ and 80℃, the coating film remains in good condition with an adhesion exceeding 10MPa. After 2000 hours of salt water resistance testing following thermal cycling, the coating film shows no rust, cracking, or peeling. Applying the coating composition to the surface of steel structures effectively prevents paint film damage and peeling caused by mechanical impact and temperature changes in low-temperature environments, thereby extending the corrosion protection life of the coating material on steel structures in polar environments. Furthermore, it is easy to prepare and suitable for large-scale production and application.

[0066] The technical solution of the present invention is further illustrated below with reference to several embodiments, but the invention is not limited to the scope of the embodiments described herein. The reagents and raw materials used in the following embodiments are all commercially available, and the test methods without specific conditions are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers. Furthermore, in the following embodiments, low-speed stirring refers to a rotation speed of 500 r / min or less, 500-2000 r / min is medium-speed stirring, and high-speed stirring refers to a rotation speed of 2000 r / min or more. High-speed dispersion refers to a rotation speed of 2000-3000 r / min.

[0067] Example 1

[0068] A method for preparing a coating composition for forming a flexible polar coating material includes the following steps:

[0069] (1) Add 1000g of a mixed solvent of xylene and butanol to a reaction vessel, add 300g of bisphenol A epoxy resin under low-speed stirring, and heat to 55℃. Stir at low speed until the epoxy resin is fully dissolved. Then add 100g of 3-isocyanate-propyltrimethoxysilane in batches. Under low-speed stirring, carry out an addition reaction at 55℃ for 2.5h to obtain Sil-EP modified resin. Then, while maintaining stirring, add 5000g of hydroxyl-terminated polydimethylsilane in batches. Then, react at 55℃ for 1.5h under stirring and cool to room temperature to obtain SER modified resin solution.

[0070] (2) 4500g of SER modified resin solution was mixed with 2300g of titanium dioxide, 100g of defoamer, 100g of rheology modifier, and 2700g of xylene and n-butanol mixed solvent in sequence and dispersed at high speed for about 30min. Then, the viscosity of the mixture was adjusted to about 120KU with 300g of xylene and butanol mixed solvent to obtain the first component.

[0071] (3) Add 1500g of polyamide resin and 8500g of xylene to the reactor, stir and disperse at medium speed for 10 minutes to obtain the second component.

[0072] (4) Mix the first component and the second component evenly at a mass ratio of about 10.2:1 to obtain a coating composition for forming a flexible polar coating material.

[0073] Example 2

[0074] A method for preparing a coating composition for forming a flexible polar coating material includes the following steps:

[0075] (1) Add 1000g of a mixed solvent of xylene and butanol to a reaction vessel, add 330g of bisphenol A epoxy resin under low-speed stirring, and heat to 65℃. Stir at low speed until the epoxy resin is fully dissolved. Then add 100g of 3-isocyanate-propyltrimethoxysilane in batches. Under low-speed stirring, carry out an addition reaction at 65℃ for 2h to obtain Sil-EP modified resin. Then, while maintaining stirring, add 5762g of hydroxyl-terminated polydimethylsilane in batches. Then, react at 65℃ for 1h under stirring and cool to room temperature to obtain SER modified resin solution.

[0076] (2) 5500g of SER modified resin solution was mixed with 2500g of titanium dioxide, 100g of defoamer, 100g of rheology modifier, and 1500g of xylene and n-butanol mixed solvent in sequence and dispersed at high speed for about 30min. Then, the viscosity of the mixture was adjusted to about 120KU with 300g of xylene and butanol mixed solvent to obtain the first component.

[0077] (3) Add 2500g of polyamide resin and 7500g of xylene to the reactor, stir and disperse at medium speed for 10 minutes to obtain the second component.

[0078] (4) Mix the first component and the second component evenly at a mass ratio of about 12.8:1 to obtain a coating composition for forming a flexible polar coating material.

[0079] Example 3

[0080] A method for preparing a coating composition for forming a flexible polar coating material includes the following steps:

[0081] (1) Add 1000g of a mixed solvent of xylene and butanol to a reaction vessel, add 320g of bisphenol A epoxy resin under low-speed stirring, and heat to 55℃. Stir at low speed until the epoxy resin is fully dissolved. Then add 100g of 3-isocyanate-propyltrimethoxysilane in batches. Under low-speed stirring, carry out an addition reaction at 55℃ for 2.5h to obtain Sil-EP modified resin. Then, while maintaining stirring, add 4290g of hydroxyl-terminated polydimethylsilane in batches. Then, react at 55℃ for 1.5h under stirring and cool to room temperature to obtain SER modified resin solution.

[0082] (2) 5000g of SER modified resin solution was mixed with 2300g of titanium dioxide, 100g of defoamer, 100g of rheology modifier and 2200g of xylene and n-butanol mixed solvent in sequence and dispersed at high speed for about 30min. Then, the viscosity of the mixture was adjusted to about 120KU with 300g of xylene and butanol mixed solvent to obtain the first component.

[0083] (3) Add 2000g of polyamide resin and 8000g of xylene to the reactor, stir and disperse at medium speed for 10 minutes to obtain the second component.

[0084] (4) Mix the first component and the second component evenly at a mass ratio of about 11.5:1 to obtain a coating composition for forming a flexible polar coating material.

[0085] Example 4

[0086] The difference between this embodiment and Embodiment 1 is that the 2300g titanium dioxide in Embodiment 1 is replaced with 300g iron oxide red, 500g talc, and 1500g silica powder.

[0087] Example 5

[0088] The difference between this embodiment and embodiment 2 is that the 2500g titanium dioxide in embodiment 2 is replaced with 500g iron oxide black, 500g talc, and 1500g silica powder.

[0089] Compare with Example 1

[0090] The preparation method of the coating composition provided in this comparative example is basically the same as that in Example 1, except that the hydroxyl-terminated polydimethylsilane in Example 1 is removed and the Sil-EP modified resin is used instead of the SER modified resin.

[0091] Compare with Example 2

[0092] The preparation method of the coating composition provided in this comparative example is basically the same as that in Example 1, except that the SER modified resin in Example 1 is replaced with conventional bisphenol A type epoxy resin E-20.

[0093] Compare with Example 3

[0094] The preparation method of the coating composition provided in this comparative example is basically the same as that in Example 1, except that the mass ratio of the first component to the second component in Example 1 is replaced with 7:1.

[0095] Compare with Example 4

[0096] The preparation method of the coating composition provided in this comparative example is basically the same as that in Example 1, except that the mass ratio of bisphenol A epoxy resin to 3-isocyanate-propyltrimethoxysilane in the preparation process of Sil-EP resin in Example 1 is replaced with 10:1.

[0097] Compare with Example 5

[0098] The preparation method of the coating composition provided in this comparative example is basically the same as that in Example 1, except that the amount of SER modified resin added in Example 1 is changed to 4000g. If the PVC content is too low, the paint film is prone to forming dark bubbles during application, which also affects the film's durability.

[0099] Compare with Example 6

[0100] The preparation method of the coating composition provided in this comparative example is basically the same as that in Example 1, except that the amount of SER modified resin added in Example 1 is changed to 6000g. Excessive PVC content results in lower impermeability / salt water resistance of the coating film and lower low-temperature toughness.

[0101] Compare with Example 7

[0102] The preparation method of the coating composition provided in this comparative example is basically the same as that in Example 1, except that in the preparation process of the Sil-EP resin in Example 1, the mass ratio of the Sil-EP modified resin to the hydroxyl-terminated polydimethylsilane is 1:15. If this ratio is too high, the viscosity of the product will be high, some silicone rubber will self-polymerize, affecting the final crosslinking density and reducing the salt water resistance.

[0103] The coating compositions of Examples 1-5 and Comparative Examples 1-7, as well as commercially available conventional low-temperature resistant coatings, were applied to the surface of sandblasted steel plates to form coatings of the same thickness. The performance of these coatings was then tested, and the corresponding test results are shown in Table 1. All test results in Table 1 are average values ​​of test results from multiple batches of products.

[0104] Table 1. Performance test results of the coating compositions of Examples 1-5 and Comparative Examples 1-7 and commercially available conventional low-temperature resistant coatings after coating formation.

[0105]

[0106] Referring to Table 1, it can be seen that the coating compositions of Examples 1-5 can form a flexible polar coating material. This coating material, when tested for adhesion, impact resistance, and flexibility at -60°C, still maintains an adhesion strength of over 11 MPa, passes the 10 Joule impact test, and exhibits a flexibility of up to 1 mm. After 30 cycles of alternating hot and cold temperatures from -60°C to 80°C, the coating film maintains good performance with an adhesion strength exceeding 10 MPa. After 2000 hours of salt water resistance testing following the alternating hot and cold temperatures, the coating film shows no rust, cracking, or peeling. Its overall performance far surpasses that of commercially available conventional low-temperature resistant coatings.

[0107] In addition, the inventors of this case also conducted experiments with other raw materials and conditions listed in this specification, referring to Examples 1-5, and obtained similar results.

[0108] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A flexible polar coating composition, characterized in that, include: The first component comprises the following components in parts by weight: 45-55 parts of SER modified resin, 20-30 parts of pigments and fillers, 1-2 parts of additives, and 20-25 parts of solvent; the second component comprises polyamide resin and solvent; the mass ratio of the first component to the second component is 10.2-12.8:

1. The SER modified resin is prepared by first performing a pre-addition reaction between bisphenol A type epoxy resin and 3-isocyanate-propyltrimethoxysilane to obtain Sil-EP modified resin, and then performing an addition reaction between the Sil-EP modified resin and hydroxyl-terminated polydimethylsilane. The mass ratio of the bisphenol A type epoxy resin to 3-isocyanate-propyltrimethoxysilane is 3.0~3.3:

1.

2. The flexible polar coating composition according to claim 1, characterized in that: The bisphenol A type epoxy resin has a weight-average molecular weight of 900~1120 and an epoxy equivalent of 450~560.

3. The flexible polar coating composition according to claim 1, characterized in that: The weight-average molecular weight of the 3-isocyanate-propyltrimethoxysilane is 200-230, and the NCO equivalent is 200-230.

4. The flexible polar coating composition according to claim 1, characterized in that: The hydroxyl-terminated polydimethylsilane has a weight-average molecular weight of 41,000 to 52,000 and a viscosity of 3,500 to 4,500 CPS.

5. The flexible polar coating composition according to claim 1, characterized in that: The mass ratio of the Sil-EP modified resin to the hydroxyl-terminated polydimethylsilane is 1:12.5~13.

4.

6. The flexible polar coating composition according to claim 1, characterized in that, The second component comprises the following components in parts by weight: 15-25 parts of polyamide resin and 75-85 parts of solvent.

7. The flexible polar coating composition according to claim 1, characterized in that: The active hydrogen equivalent of the polyamide resin is 275~285.

8. The flexible polar coating composition according to claim 1, characterized in that: The pigments and fillers include any one or more combinations of titanium dioxide, iron oxide black, iron oxide red, talc, and silica powder.

9. The flexible polar coating composition according to claim 1, characterized in that: The additives include any one or more combinations of defoamers, leveling agents, and rheology modifiers.

10. The flexible polar coating composition according to claim 1, characterized in that: The solvent includes any one or more combinations of xylene, propylene glycol methyl ether, methyl isobutyl ketone, acetone, n-butanol, and acetylacetone.

11. The method for preparing the flexible polar coating composition according to any one of claims 1-10, characterized in that, include: First, bisphenol A type epoxy resin is pre-added to 3-isocyanate-propyltrimethoxysilane to obtain Sil-EP modified resin. Then, Sil-EP modified resin is added to hydroxyl-terminated polydimethylsilane to obtain SER modified resin. The SER-modified resin, pigments, fillers, additives, and solvent are mixed evenly to obtain the first component; The polyamide resin and solvent are mixed evenly to obtain the second component; The first component and the second component are mixed evenly to obtain the flexible polar coating composition.

12. The preparation method according to claim 11, characterized in that, include: Bisphenol A type epoxy resin was added to a mixed solvent containing xylene and butanol and heated to 55-65℃ to dissolve it completely. Then, 3-isocyanate-propyltrimethoxysilane was added in batches until the mass ratio of bisphenol A type epoxy resin to 3-isocyanate-propyltrimethoxysilane was 3.0-3.3:

1. The pre-addition reaction was then carried out at 55-65℃ for 2-2.5 hours under stirring to obtain Sil-EP modified resin. Hydroxyl-terminated polydimethylsilane was added in batches under stirring until the mass ratio of Sil-EP modified resin to hydroxyl-terminated polydimethylsilane was 1:12.5~13.

4. Then, an addition reaction was carried out at 55~65℃ for 1~1.5h under stirring to obtain the SER modified resin.

13. The preparation method according to claim 12, characterized in that: The bisphenol A type epoxy resin has a weight-average molecular weight of 900~1120 and an epoxy equivalent of 450~560.

14. The preparation method according to claim 12, characterized in that: The weight-average molecular weight of the 3-isocyanate-propyltrimethoxysilane is 200-230, and the NCO equivalent is 200-230.

15. The preparation method according to claim 12, characterized in that: The hydroxyl-terminated polydimethylsilane has a weight-average molecular weight of 41,000 to 52,000 and a viscosity of 3,500 to 4,500 CPS.

16. The preparation method according to claim 11, characterized in that: The mass ratio of the first component to the second component is 10.2~12.8:

1.

17. A flexible polar coating material, characterized in that, The flexible polar coating material is formed from any one of the flexible polar coating compositions according to claims 1-10.

18. The flexible polar coating material according to claim 17, characterized in that: The dry film thickness of the flexible polar coating material is less than 200µm.

19. The application of the flexible polar coating composition of any one of claims 1-10 or the flexible polar coating material of any one of claims 17-18 in the coating protection of steel in polar environments.

20. A method for surface protection of steel substrates in polar environments, characterized in that, include: The flexible polar coating composition of any one of claims 1-10 is applied to the surface of a steel substrate to form a protective coating.

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