Low-shrinkage high-corrosion-resistant glass flake coating and preparation method thereof

Abstract

This invention discloses a low-shrinkage, highly corrosion-resistant glass flake coating and its preparation method. The coating comprises a main agent, which is mainly prepared from the following components in the following weight ratios: 45-65 parts epoxy vinyl unsaturated polyester resin, 20-30 parts glass flakes, 1-3 parts fluorinated toughening modifier, 0.1-2 parts dispersant, 0.1-1 part defoamer, 0.1-3 parts thixotropic agent, 1-15 parts unsaturated polyester reactive diluent, and 1-15 parts acid and alkali resistant powder; the epoxy vinyl unsaturated polyester resin includes phenolic epoxy vinyl unsaturated polyester resin. The coating of this invention exhibits excellent heat resistance and structural stability, and demonstrates superior toughness and acid resistance at high temperatures. It effectively reduces volume shrinkage during curing, achieving low shrinkage performance and extending the service life of the coating.

Description

Technical Field

[0001] This application relates to the field of anti-corrosion coating technology, and in particular to a low-shrinkage, high-corrosion-resistant glass flake coating and its preparation method. Background Technology

[0002] Driven by the goals of "carbon peaking and carbon neutrality," the demand for carbon capture, utilization, and storage (CCUS) technologies is growing, especially for desulfurization technologies targeting the large amounts of flue gas emitted from thermal power plants, steel mills, and incineration plants. Currently, limestone-gypsum wet flue gas desulfurization technology is widely used in industry due to its mature facilities, high desulfurization efficiency, high absorbent utilization rate, and low raw material costs; therefore, it will remain a mainstream technology for some time to come. The interior of desulfurization towers typically uses non-metallic materials such as rubber, reinforced resin linings (glass flake coating), and fiber-reinforced plastics as corrosion-resistant materials to resist corrosion from acidic flue gas and humid, hot environments.

[0003] Among numerous anti-corrosion materials, resin-based glass flake coatings have become the primary protection solution for the interior of desulfurization towers due to their excellent corrosion resistance, low permeability, high bonding strength, and long service life. However, existing coatings generally suffer from problems such as thermal shrinkage leading to cracking, coating embrittlement, interface peeling, poor acid and alkali resistance, and insufficient weather resistance under long-term high-temperature, strong acid and alkali, and humid heat cycling conditions. These issues limit the extension of the protection cycle and increase the frequency of equipment maintenance and operating costs.

[0004] The operating environment inside desulfurization towers is extremely harsh, with high flue gas temperatures, strong corrosiveness, high solids content, and high abrasiveness. Coatings must simultaneously possess low shrinkage, high corrosion resistance, high temperature resistance, and long-term stability. Especially under sulfuric acid dew point conditions, traditional vinyl ester and epoxy resin-based glass flake coatings are prone to internal stress due to curing or thermal shrinkage, leading to coating cracking and failure, thus failing to guarantee long-term reliable protection. Chinese invention patent application publication number CN106479327 B (A Vinyl Ester Resin Glass Flake Putty Coating) provides a method for low-shrinkage modification of vinyl ester system putties. Its low-shrinkage agent relies on polyether isocyanates; however, polyether segments are easily degraded under high temperature and strong acid conditions. This modification method makes the coating unsuitable for use in the strong acid environment of high-temperature desulfurization towers.

[0005] Therefore, developing a glass flake coating that maintains low shrinkage and high corrosion resistance under high-temperature corrosive, acidic, and humid heat cycling environments is of great significance for extending the service life of desulfurization towers and similar industrial equipment, reducing operation and maintenance costs, and improving operational stability. Such coatings not only require excellent chemical stability and mechanical properties, but also need to exhibit good operability and durability during application, curing, and service to meet the long-term usage requirements of harsh industrial environments. Summary of the Invention

[0006] In view of this, this application provides a low-shrinkage, high-corrosion-resistant glass flake coating and its preparation method. The coating of the present invention has good heat resistance and structural stability, and has excellent toughness and acid resistance in high-temperature environments. It can effectively reduce volume shrinkage during the curing process, achieve low shrinkage performance of the coating, and extend the service life of the coating.

[0007] To achieve the above objectives, this application employs the following technical solution: A low-shrinkage, highly corrosion-resistant glass flake coating includes a main agent, which is mainly prepared from the following components in the following weight ratios: 45-65 parts of epoxy vinyl unsaturated polyester resin, 20-30 pieces of glass flakes 1-3 parts of fluorinated toughening modifier, Dispersant 0.1-2 parts, Defoamer 0.1-1 part, Thixotropic agent 0.1-3 parts; 1-15 parts of unsaturated polyester reactive diluent 1-15 parts of acid and alkali resistant powder; The epoxy vinyl unsaturated polyester resin comprises phenolic epoxy vinyl unsaturated polyester resin.

[0008] This invention employs phenolic epoxy vinyl unsaturated polyester resin to enhance the system's heat resistance and structural stability. A fluorinated toughening modifier is introduced into the vinyl ester resin system, and the system is optimized using the "free volume theory." This significantly improves the coating's toughness and acid resistance under high-temperature conditions, effectively reduces volume shrinkage during curing, and ultimately extends the coating's service life. An unsaturated polyester reactive diluent is used to adjust the system's viscosity and application properties. Acid and alkali resistant powders are used to enhance the coating's density and resistance to media penetration.

[0009] Specifically, the low-shrinkage, high-corrosion-resistant glass flake coating also includes a peroxide-based curing agent; the mass ratio of the main agent to the peroxide-based curing agent when used in combination is 100: 1.0-2.0.

[0010] Specifically, the peroxide-based curing agent is preferably one or a mixture of two or more of methyl ethyl ketone peroxide, cumene peroxide, or tert-butyl benzoate peroxide in any proportion.

[0011] Specifically, the fluorinated toughening modifier is preferably polytetrafluoroethylene fine powder with an average particle size of no more than 35 μm, used to improve the flexibility and crack resistance of the coating.

[0012] Specifically, the particle size distribution of the glass flakes is 100-400 mesh, preferably 150-200 mesh, to ensure that the coating has excellent shielding performance while also taking into account the leveling and density of the coating during construction.

[0013] Specifically, the key physicochemical parameters of the phenolic epoxy vinyl unsaturated polyester resin are: density 1.05-1.10 g / cm³. 3 It has a styrene content of 30-36% and a viscosity of 400-550 mPa·s at 25℃.

[0014] Specifically, the epoxy vinyl unsaturated polyester resin may be composed of phenolic epoxy vinyl unsaturated polyester resin; Alternatively, the epoxy vinyl unsaturated polyester resin may also be composed of phenolic epoxy vinyl unsaturated polyester resin and bisphenol A type epoxy vinyl unsaturated polyester resin, and the weight of the bisphenol A type epoxy vinyl unsaturated polyester resin is less than or equal to 30% of the total weight of the epoxy vinyl unsaturated polyester resin.

[0015] Phenolic epoxy vinyl unsaturated polyester resin, as the main resin, provides excellent resistance to acids, alkalis and solvents. Bisphenol A type epoxy vinyl unsaturated polyester resin is mainly used to improve the flowability of the work, but its resistance (temperature resistance and high corrosion resistance) is slightly lower. If its proportion exceeds 30% of the total resin, it will significantly reduce the chemical stability of the system.

[0016] Specifically, the unsaturated polyester reactive diluent is preferably styrene. After adding an appropriate amount of styrene unsaturated polyester reactive diluent, the system exhibits good fluidity and dispersion stability in the container, while also helping the curing reaction to proceed uniformly, thereby further optimizing the coating density and surface smoothness. The acid and alkali resistant powder is preferably one or more of titanium dioxide, barium sulfate, and silicon dioxide, which can improve the density and resistance to media penetration of the coating. The dispersant is preferably an aliphatic amide compound, used to improve the dispersibility of pigments and fillers; The defoamer is preferably a polysiloxane compound, used to suppress the generation of bubbles in the coating during dispersion and application. The thixotropic agent is preferably hydrophobic fumed silica, used to improve the thixotropy and workability of the system.

[0017] Specifically, the key physicochemical parameters of the bisphenol A type epoxy vinyl unsaturated polyester resin are: solid content 60-65%; acid value 5-15 mgKOH / g; viscosity at 25℃ 400-550 mPa·s.

[0018] To achieve the above objectives, the present invention also provides a method for preparing the aforementioned low-shrinkage, high-corrosion-resistant glass flake coating, wherein the preparation method of the main agent includes the following steps: (1) Preparation of slurry: Take 60-80% of epoxy vinyl unsaturated polyester resin as base material, add fluorinated toughening modifier, dispersant, thixotropic agent, acid and alkali resistant powder, 30-60% of defoamer and 20-40% of unsaturated polyester active diluent, and stir at high speed of 800-1200 rpm in a stirring tank for 25-35 minutes until the system is uniform to obtain premixed slurry; (2) Dispersion of glass flakes: Adjust the speed of the mixing vessel to 200-400 rpm, and gradually add glass flakes to the premixed slurry while continuously stirring. Then, keep the speed unchanged and continue stirring for 20-30 minutes to make the glass flakes evenly dispersed in the system and form a stable shielding skeleton. (3) Paint preparation: After the glass flakes are evenly dispersed, add the remaining defoamer, the remaining epoxy vinyl unsaturated polyester resin, and the remaining unsaturated polyester reactive diluent. Then, keep the speed constant and continue stirring for 20-30 minutes until the system is uniform. Filter to obtain the main agent. A filter screen of about 80 mesh can be used for filtration.

[0019] Specifically, when using it, the main agent is mixed evenly with the peroxide-based curing agent.

[0020] The coating prepared by this invention has the following performance characteristics (see Table 1 in the specific embodiments for details): High temperature corrosion resistance: Under a series of conditions from 80% sulfuric acid at room temperature to 25% sulfuric acid at 90℃, no bubbling or peeling occurred after immersion for 7 days; Alkali resistance: No bubbling or peeling occurred after soaking in 25% KOH (65℃) and 10% KOH (65℃) for 7 days; Heat resistance: No peeling after being heated at 175℃ for 4 hours; It exhibits excellent resistance to salt, water, and solvents (xylene); immersion for 7 days does not affect the integrity of the coating. It has good construction performance and is suitable for on-site applications in industrial pipelines and complex working conditions.

[0021] Compared with the prior art, this invention application has the following advantages: (1) This invention rationally designs the resin formulation and optimizes the coating molecular structure. The phenolic epoxy vinyl unsaturated polyester resin molecule contains benzene rings and hydroxymethyl bridging bonds, resulting in high molecular chain rigidity and an increased thermal decomposition temperature, which helps improve the thermal stability and creep resistance of the system. Simultaneously, the conjugated system of the benzene ring structure can disperse stress concentration points, providing a stable skeletal environment for the synergistic effect of subsequent fluorinated toughening modifiers. The coating of this invention exhibits excellent durability and service life, and can meet the long-term protection requirements under varying working conditions.

[0022] (2) This invention employs a fluorinated toughening modifier, which is fine polytetrafluoroethylene (PTFE) powder with low surface energy and high free volume. In the vinyl resin curing system, the micron-sized PTFE particles, due to their low surface energy, form a "sea-island structure" with microscopic phase separation from the matrix resin. When the coating undergoes curing shrinkage or thermal shock, these micro-regions can induce the formation of crazes and passivate the crack tips, thereby effectively dispersing and releasing interfacial stress and reducing the concentration of internal stress generated during curing. By introducing a fluorinated toughening modifier, the system can be toughened without complex chemical grafting modification, significantly reducing the risk of cracking caused by coating curing shrinkage and improving the toughness and structural stability of the coating under high-temperature conditions.

[0023] (3) By optimizing the amount and distribution of glass flakes, this invention forms a multi-layer shielding structure, which can effectively prevent the corrosive medium from penetrating and diffusing along the thickness direction, and significantly prolong the life of corrosive media (such as H). + Cl - SO4 2- The penetration path of the coating creates a typical "maze effect," which significantly improves the corrosion resistance of the coating and reduces the permeability of corrosive media, effectively extending the protective life of the coating.

[0024] (4) The components and proportions of the coating of the present invention are reasonable. By reasonably compounding acid and alkali resistant powders and dispersants, the construction performance and density of the coating are further improved, so that it has good operability and stable anti-corrosion effect in practical applications. Attached Figure Description

[0025] Figure 1 Comparative diagrams showing the heat resistance of the coatings applied in Example 1 and Comparative Example 2 of this application. Figure 2 This is a schematic diagram of the "maze effect" in Embodiments 1-3 of this application. (Where the horizontal lines represent glass flakes and the red curves represent the intrusion path of the corrosive medium.) Detailed Implementation

[0026] The exemplary embodiments of the present invention are described in more detail below. These embodiments are intended to provide a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art. While exemplary embodiments of the present invention are shown, it should be understood that the invention should not be limited to the embodiments set forth herein.

[0027] In the embodiments of the present invention, unless otherwise specified, the specific selection of each component is as follows: Fluorine-containing toughening modifier (PTFE fine powder): PTFE fine powder with an average particle size of approximately 20 μm is selected.

[0028] Dispersant (aliphatic amide compound): BYK ANTI-TERRA was selected. Its main components are unsaturated polyamine amide and low molecular weight acid polyester salt solution. The solvent system is ethylene glycol butyl ether with 80% non-volatile content.

[0029] Defoamer (polysiloxane compound): TEGO 900 is selected, whose main component is a polysiloxane compound containing hydrophobic particles.

[0030] Thixotropic agent (hydrophobic fumed silica): Hydrophobic fumed silica AEROSIL R972 is selected.

[0031] Unsaturated polyester reactive diluent (styrene): Styrene, industrial grade. Example 1

[0032] A low-shrinkage, highly corrosion-resistant glass flake coating includes a main agent, which is mainly prepared from the following components in the following weight ratios: 52.5 parts of phenolic epoxy vinyl unsaturated polyester resin 7.5 parts of unsaturated polyester reactive diluent Glass flakes (150 mesh) 24.5 parts, Acid and alkali resistant powder (barium sulfate) 8.5 parts, 1.1 parts dispersant, 0.6 parts of defoamer 1.8 parts thixotropic agent 1.8 parts of fluorine-containing toughening modifier.

[0033] Preparation steps: (1) Preparation of slurry: Take 80% of phenolic epoxy vinyl unsaturated polyester resin (42.0 parts) as base material, add 1.8 parts of fluorine toughening modifier, 8.5 parts of acid and alkali resistant powder, 1.1 parts of dispersant, 50% of defoamer (0.3 parts), 1.8 parts of thixotropic agent, and part of unsaturated polyester reactive diluent (2.5 parts), stir in a mixing tank at 1000 rpm for 30 minutes until the system is uniform to obtain premixed slurry; (2) Dispersion of glass flakes: Adjust the speed of the mixing vessel to 300 rpm, and gradually add 24.5 parts of glass flakes to the premixed slurry while continuously stirring. Then, keep the speed unchanged and continue stirring for 25 minutes to make the glass flakes evenly dispersed to form a stable shielding structure. (3) Paint preparation: After the glass flakes are evenly dispersed, add the remaining phenolic epoxy vinyl unsaturated polyester resin (10.5 parts), the remaining defoamer (0.3 parts), and the remaining unsaturated polyester active diluent (5.0 parts). Then, keep the speed constant and continue stirring for 25 minutes until the system is uniform. After filtering (80 mesh filter), fill and seal to obtain the main agent.

[0034] When using, mix the main agent and the peroxide-based curing agent (methyl ethyl ketone peroxide) at a mass ratio of 100:1.5 and cure them evenly. The curing conditions are a temperature of 30°C and a relative humidity of 50%. Example 2

[0035] A low-shrinkage, highly corrosion-resistant glass flake coating includes a main agent, which is mainly prepared from the following components in the following weight ratios: Phenolic epoxy vinyl unsaturated polyester resin (main resin) 42.5 parts, Bisphenol A type epoxy vinyl unsaturated polyester resin (auxiliary resin) 10.0 parts, 7.5 parts of unsaturated polyester reactive diluent Glass flakes (150 mesh) 24.5 parts, Acid and alkali resistant powder (barium sulfate) 8.5 parts, 1.1 parts dispersant, 0.6 parts of defoamer 1.8 parts thixotropic agent 1.8 parts of fluorine-containing toughening modifier.

[0036] Preparation steps: (1) Preparation of slurry: Take 80% of the main resin (34.0 parts) and 80% of the auxiliary resin (8.0 parts) as the base material, add 1.8 parts of fluorine toughening modifier, 8.5 parts of acid and alkali resistant powder, 1.1 parts of dispersant, 50% of defoamer (0.3 parts), 1.8 parts of thixotropic agent and part of unsaturated polyester reactive diluent (2.5 parts), stir in a mixing tank at 1000 rpm for 30 minutes until the system is uniform to obtain premixed slurry; (2) Dispersion of glass flakes: Adjust the speed of the mixing vessel to 300 rpm, and gradually add 24.5 parts of glass flakes to the premixed slurry while continuously stirring. Then, keep the speed unchanged and continue stirring for 25 minutes to make the glass flakes evenly dispersed to form a stable shielding structure. (3) Paint preparation: After the glass flakes are evenly dispersed, add the remaining main resin (8.5 parts), the remaining auxiliary resin (2.0 parts), the remaining defoamer (0.3 parts), and the remaining unsaturated polyester reactive diluent (5.0 parts). Then, keep the speed constant and continue stirring for 20 minutes until the system is uniform. After filtering (80 mesh filter), fill and seal to obtain the main agent.

[0037] When using, the mixing ratio of the peroxide curing agent and the main agent, as well as the curing conditions, are the same as in Example 1. Example 3

[0038] A low-shrinkage, highly corrosion-resistant glass flake coating includes a main agent, which is mainly prepared from the following components in the following weight ratios: Phenolic epoxy vinyl unsaturated polyester resin (main resin) 42.5 parts, Bisphenol A type epoxy vinyl unsaturated polyester resin (auxiliary resin) 10.0 parts, 7.5 parts of unsaturated polyester reactive diluent Glass flakes (200 mesh) 24.5 parts, Acid and alkali resistant powder 1 (barium sulfate) 5.5 parts, Acid and alkali resistant powder 2 (titanium dioxide) 3.0 parts, 1.1 parts dispersant, 0.6 parts of defoamer 1.8 parts thixotropic agent 1.8 parts of fluorine-containing toughening modifier.

[0039] Preparation steps: (1) Preparation of slurry: Take 80% of the main resin (34.0 parts) and 80% of the auxiliary resin (8.0 parts) as base material, add 1.8 parts of fluorine toughening modifier, 5.5 parts of acid and alkali resistant powder barium sulfate, 3.0 parts of titanium dioxide, 1.1 parts of dispersant, 50% of defoamer (0.3 parts), 1.8 parts of thixotropic agent, and part of unsaturated polyester reactive diluent (2.5 parts), stir in a mixing tank at 1000 rpm for 30 minutes until the system is uniform to obtain premixed slurry; (2) Dispersion of glass flakes: Adjust the speed of the mixing vessel to 300 rpm, and gradually add 24.5 parts of glass flakes to the premixed slurry while continuously stirring. Then, keep the speed unchanged and continue stirring for 25 minutes to make the glass flakes evenly dispersed to form a dense shielding structure. (3) Paint preparation: After the glass flakes are evenly dispersed, add the remaining main resin (8.5 parts), the remaining auxiliary resin (2.0 parts), the remaining defoamer (0.3 parts), and the remaining unsaturated polyester reactive diluent (5.0 parts). Then, keep the speed constant and continue stirring for 20 minutes until the system is uniform. After filtering (80 mesh filter), fill and seal to obtain the main agent.

[0040] When using, mix the main agent and the peroxide-based curing agent (a mixture of methyl ethyl ketone peroxide and cumene peroxide in a mass ratio of 1:1) at a mass ratio of 100:1.5 and cure them evenly. The curing conditions are a temperature of 30℃ and a relative humidity of 50%.

[0041] Example 4

[0042] A low-shrinkage, highly corrosion-resistant glass flake coating includes a main agent, which is mainly prepared from the following components: 65 parts of phenolic epoxy vinyl unsaturated polyester resin 1.0 part of unsaturated polyester reactive diluent 20 portions of glass flakes (100 mesh). Acid and alkali resistant powder (barium sulfate) 1.0 part, 0.1 parts dispersant, 0.1 parts of defoamer Thixotropic agent 3.0 parts, 3.0 parts of fluorine-containing toughening modifier.

[0043] Preparation steps: (1) Preparation of slurry: Take 60% of resin (39.0 parts) as base material, add 3.0 parts of fluorine toughening modifier, 1.0 part of acid and alkali resistant powder, 0.1 part of dispersant, 30% of defoamer (0.03 parts), 3.0 parts of thixotropic agent, and 20% of unsaturated polyester reactive diluent (0.2 parts), and stir in a mixing tank at 800 rpm for 25 minutes to obtain premixed slurry; (2) Glass flake dispersion: Adjust the speed to 200 rpm, and while continuously stirring, gradually add 20 parts of glass flakes to the premixed slurry, and then continue stirring for 20 minutes while keeping the speed constant; (3) Paint preparation: After the glass flakes are evenly dispersed, add the remaining resin (26 parts), the remaining defoamer (0.07 parts), and the remaining unsaturated polyester active diluent (0.8 parts). Then, keep the speed constant and continue stirring for 20 minutes until the system is uniform. After filtering (80 mesh filter), fill and seal to obtain the main agent.

[0044] When using, mix the main agent and the peroxide-based curing agent (methyl ethyl ketone peroxide) at a mass ratio of 100:1.0 until homogeneous, and the curing conditions are the same as in Example 1.

[0045] Example 5

[0046] A low-shrinkage, highly corrosion-resistant glass flake coating includes a main agent, which is mainly prepared from the following components: 45 parts of phenolic epoxy vinyl unsaturated polyester resin 15 parts of unsaturated polyester reactive diluent 30 portions of glass flakes (400 mesh). 15 parts of acid and alkali resistant powder (barium sulfate) 2.0 parts of dispersant 1.0 part of defoamer 0.1 parts thixotropic agent, 1.0 part of fluorine-containing toughening modifier.

[0047] Preparation steps: (1) Preparation of slurry: Take 70% of the resin (31.5 parts) as the base material, add 1.0 part of fluorine toughening modifier, 15 parts of acid and alkali resistant powder, 2.0 parts of dispersant, 60% of defoamer (0.6 parts), 0.1 parts of thixotropic agent, and 40% of unsaturated polyester reactive diluent (6 parts), and stir in a mixing tank at 1200 rpm for 35 minutes to obtain premixed slurry; (2) Glass flake dispersion: Adjust the speed to 400 rpm, and while continuously stirring, gradually add 30 parts of glass flakes to the premixed slurry, and then continue stirring for 30 minutes while keeping the speed constant; (3) Paint preparation: After the glass flakes are evenly dispersed, add the remaining resin (13.5 parts), the remaining defoamer (0.4 parts), and the remaining unsaturated polyester active diluent (9 parts). Then, keep the speed constant and continue stirring for 30 minutes. After filtering (80 mesh filter), fill and seal to obtain the main agent.

[0048] When using, mix the main agent and the peroxide-based curing agent (methyl ethyl ketone peroxide) at a mass ratio of 100:2.0 until homogeneous, and the curing conditions are the same as in Example 1. Example 6

[0049] The rest is the same as in Example 1, except that the acid and alkali resistant powder is different, the 8.5 parts of barium sulfate in Example 1 are replaced with an equal amount of silicon dioxide, and the methyl ethyl ketone peroxide is replaced with cumene peroxide. Example 7

[0050] The rest is the same as in Example 2, except that the resin in the main agent is adjusted to: 36.75 parts of phenolic epoxy vinyl unsaturated polyester resin and 15.75 parts of bisphenol A type epoxy vinyl unsaturated polyester resin (i.e., bisphenol A type epoxy vinyl unsaturated polyester resin accounts for 30% of the total resin weight of 52.5 parts). Methyl ethyl ketone peroxide is replaced with tert-butyl benzoate peroxide.

[0051] Comparative Example 1

[0052] Comparative Example 1 is the same as Example 1, except that 52.5 parts of phenolic epoxy vinyl unsaturated polyester resin were replaced with an equal amount of bisphenol A type epoxy vinyl unsaturated polyester resin.

[0053] Comparative Example 2

[0054] Comparative Example 2 is the same as Example 1, except that 1.8 parts of fluorinated toughening modifier (PTFE fine powder) were replaced with an equal amount of ordinary polypropylene (PP) powder (non-fluorinated toughening modifier).

[0055] In the above embodiments and comparative examples, the key physicochemical parameters of the phenolic epoxy vinyl unsaturated polyester resin are: density 1.05-1.10 g / cm³. 3 The styrene content is 30-36%, and the viscosity at 25℃ is 400-550 mPa·s. The key physicochemical parameters of the bisphenol A type epoxy vinyl unsaturated polyester resin are: solid content 60-65%, acid value 5-15 mgKOH / g, and viscosity at 25℃ 400-550 mPa·s. The above physicochemical parameters are typical measured values ​​of the resin used in this invention, and they fall within the range of physicochemical parameters defined by this invention. Those skilled in the art can select equivalent resins that meet the parameter range without departing from the technical effect of this invention.

[0056] The performance of Examples 1-7 and Comparative Examples 1-2 was tested according to the following standards: Basic performance: Referring to other product indicators in HG / T 4336-2012 glass flake anticorrosion coatings, the standard values ​​are as follows: State in container: After stirring, there are no hard lumps and the state is uniform; Coating appearance: Normal.

[0057] Heat resistance: GB / T 1735-2009 Determination of heat resistance of paints and varnishes.

[0058] Acid and alkali resistance: GB / T 1763-2018 Determination of chemical resistance of paints and varnishes.

[0059] Water resistance: GB / T 1733-1993 Test method for water resistance of paint film.

[0060] Salt resistance: GB / T 1763-2018 Determination of chemical resistance of paints and varnishes.

[0061] Solvent resistance: GB / T 23989-2009 Determination of solvent resistance of coatings by wiping test.

[0062] Table 1 Key performance test results of Examples 1-7 and Comparative Examples 1-2

[0063] From the above embodiments and comparative examples, we can conclude that: Example 4 shows that: with a high resin base content, in order to prevent excessive exothermic polymerization (bursting polymerization) from a large number of reactive groups, the curing agent was controlled at an extremely low limit (the amount of curing agent was 1.0% of the main agent). At the same time, in order to address the high volume shrinkage caused by high resin and the easy sagging caused by low powder, the fluorinated toughening modifier and thixotropic agent were increased to the upper limit (3.0 parts). The results showed that although the coating film yellowed slightly more when heated due to less powder barrier, it successfully resisted the high shrinkage stress and no cracking occurred.

[0064] Example 5 shows that when glass flakes and acid / alkali resistant powder reach their upper limits, they form extremely high solids resistance. To ensure complete cross-linking, the curing agent is increased to its upper limit (curing agent dosage is 2.0% of the main agent), while a high proportion of unsaturated polyester reactive diluent, dispersant, and defoamer is added. The results show that the system successfully overcomes the high viscosity application challenge, and the coating, though slightly rough, exhibits extremely strong shielding and corrosion protection.

[0065] Examples 6 and 7 demonstrate the feasibility of using silica as an acid and alkali resistant powder and cumene peroxide and tert-butyl benzoate peroxide as equivalent curing agents in the formulation. In Example 6, after replacing barium sulfate with an equal amount of silica, the system viscosity increased slightly and the gloss decreased slightly due to the higher oil absorption and matting properties of silica. Example 7 strongly demonstrates that even when the amount of bisphenol A type epoxy vinyl unsaturated polyester resin used as an auxiliary resin is as high as 30% of the total resin, the high-temperature corrosion resistance of the system remains stable.

[0066] Comparative Example 1 shows that when phenolic epoxy vinyl unsaturated polyester resin is not used as the main resin, but only bisphenol A type epoxy vinyl unsaturated polyester resin is used, loss of gloss, bubbling or softening occurs under high temperature, acid, alkali and solvent environments, proving the key role of phenolic epoxy vinyl unsaturated polyester resin in high temperature heavy corrosion protection.

[0067] Comparative Example 2 shows that, without the addition of a fluorinated toughening modifier, the resulting coating exhibits acceptable acid and alkali resistance at room temperature, but significant cracking and localized peeling occur under high-temperature testing at 175°C. This indicates that under high-temperature environments and thermal stress, the system is prone to generating significant shrinkage stress, leading to crack propagation. In contrast, this invention, by introducing a fluorinated toughening modifier, forms a stable and dispersed fluorinated microphase structure within the system, which can alleviate thermal stress concentration to a certain extent, thereby effectively improving the coating's resistance to thermal cracking and high-temperature stability.

[0068] Figure 1 In Figure a, the coating prepared in Example 1 is shown after application. The left side of Figure a shows the initial state of the coating, which is white. The right side of Figure a shows slight yellowing after being heated at 175 degrees Celsius for 4 hours (this is a normal phenomenon). Figure b shows the state of the coating prepared in Comparative Example 2 after being heated at 175 degrees Celsius for 4 hours. Due to poor heat resistance, it shrinks and peels off the substrate, bending the substrate. The color is more yellow than the right side of Figure a. Figure 1 This indicates that the addition of a small amount of fluorine-containing toughening modifier alleviated thermal shrinkage stress through the free volume effect.

[0069] The above conclusion can also be supported theoretically: (1) The structural role of the main resin The phenolic epoxy vinyl unsaturated polyester resin contains benzene rings and hydroxymethyl bridging bonds, resulting in high molecular chain rigidity and an increased thermal decomposition temperature, which helps improve the system's thermal stability and creep resistance. Simultaneously, the conjugated system of the benzene ring structure can disperse stress concentration points, providing a stable skeletal environment for the synergistic effect of subsequent fluorinated toughening modifiers.

[0070] (2) Synergistic effect of fluorine-containing toughening modifiers Fluorinated toughening modifiers exhibit low polarizability and high bond energy at the molecular level. The CF bond has a length of approximately 1.35 Å and a bond energy of approximately 4.85 eV, demonstrating high stability among common covalent bonds. Compared to conventional non-fluorinated toughening materials, these fluorinated polymer structures exhibit superior thermal and chemical stability under high-temperature and strong oxidizing environments. Under thermal shock conditions exceeding 175°C and in the high-concentration sulfuric acid dew point environment of desulfurization towers, the fluorinated structure maintains molecular structural stability, resisting thermal degradation or oxidative damage, thus preserving the microstructural integrity of the system. Simultaneously, the significant steric hindrance and low polarizability of the fluorinated structure result in a weaker response to changes in external electric fields, which is beneficial for improving the system's chemical resistance and structural stability in acidic and high-temperature oxidizing environments.

[0071] (3) Synergy between “free volume theory” regulation and flexible microphase This invention designs the molecular structure of the system based on the "Free Volume Theory." The introduction of a fluorinated toughening modifier into the vinyl ester resin system significantly increases the irregular stacking between chain segments, thereby increasing the free volume fraction (Vf) of the system. The increase in free volume means that during resin curing and crosslinking reactions, the molecular chains have higher degrees of freedom of movement, enabling spontaneous stress buffering and local structural rearrangement when crosslinking shrinkage stress occurs. According to the free volume theory, the curing shrinkage rate of the system is inversely proportional to the free volume; therefore, increasing Vf can significantly reduce volume shrinkage and internal stress accumulation during the thermosetting stage.

[0072] In addition, the low surface energy and highly flexible chain segment structure of the fluorinated toughening modifier enable it to form flexible microphase domains in the cured network. These microphase domains can further absorb thermal stress and external mechanical stress, thereby achieving stress dispersion and dissipation, thus avoiding the cracking, brittle fracture and interface peeling problems that occur in traditional vinyl ester systems during high-temperature curing or service.

[0073] In summary, through the synergistic effect of free volume regulation and flexible microphase, this invention achieves a comprehensive performance improvement in low shrinkage, high toughness, and high heat resistance while maintaining the system's high crosslinking density and chemical stability.

[0074] (4) Strengthening effect of glass flakes at the matrix interface Due to the excellent compatibility of fluorinated polymers (i.e., fluorinated toughening modifiers) on the surface of glass flakes, a flexible transition layer can be formed between the flakes and the resin matrix, reducing the risk of stress concentration and delamination at the interface. Simultaneously, the glass flakes are distributed in parallel or staggered orientations within the system, forming a continuous multi-layered shielding structure that effectively hinders the penetration and diffusion of corrosive media along the thickness direction, significantly extending the lifespan of corrosive media (such as H₂O₂). + Cl - SO42- The permeation path creates a typical "maze effect." This structure not only effectively blocks the diffusion and penetration of corrosive media, but also, with the synergistic effect of fluorinated polymers, makes the interfacial bonding of flexible phases between the flakes more stable, thereby further improving the coating's acid resistance, water resistance, and long-term adhesion retention performance.

[0075] In summary, this invention addresses the problems of thermal shrinkage cracking, insufficient toughness, poor acid resistance, and unstable curing time in existing vinyl ester and epoxy resin-based glass flake coatings during high-temperature or curing processes. It provides a low-shrinkage, high-corrosion-resistant vinyl ester glass flake coating and its preparation method. By introducing a fluorinated toughening modifier into the vinyl ester resin system and designing the molecular chain using the "free volume theory," this invention significantly increases the degree of freedom of the molecular chain, thereby eliminating internal stress generated during curing or heating, achieving low shrinkage performance of the coating, effectively solving the problem of easy cracking in traditional coatings, and simultaneously improving the toughness and acid resistance of the coating under high temperature and complex working conditions, extending the service life of the coating.

[0076] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A low-shrinkage, highly corrosion-resistant glass flake coating, characterized in that: The main agent is prepared from the following components in the following weight ratios: 45-65 parts of epoxy vinyl unsaturated polyester resin, 20-30 pieces of glass flakes 1-3 parts of fluorinated toughening modifier, Dispersant 0.1-2 parts, Defoamer 0.1-1 part, Thixotropic agent 0.1-3 parts, 1-15 parts of unsaturated polyester reactive diluent 1-15 parts of acid and alkali resistant powder; The epoxy vinyl unsaturated polyester resin comprises phenolic epoxy vinyl unsaturated polyester resin.

2. The low-shrinkage, high-corrosion-resistant glass flake coating according to claim 1, characterized in that: The low-shrinkage, high-corrosion-resistant glass flake coating also includes a peroxide-based curing agent; the mass ratio of the main agent to the peroxide-based curing agent when used in combination is 100: 1.0-2.

0.

3. The low-shrinkage, high-corrosion-resistant glass flake coating according to claim 2, characterized in that: The peroxide curing agent is one or a mixture of two or more of methyl ethyl ketone peroxide, cumene peroxide, or tert-butyl benzoate peroxide in any proportion.

4. The low-shrinkage, high-corrosion-resistant glass flake coating according to claim 2, characterized in that: The fluorinated toughening modifier is polytetrafluoroethylene fine powder.

5. The low-shrinkage, high-corrosion-resistant glass flake coating according to claim 2, characterized in that: The glass flakes have a particle size distribution range of 100 mesh to 400 mesh.

6. The low-shrinkage, high-corrosion-resistant glass flake coating according to claim 2, characterized in that: The key physicochemical parameters of the phenolic epoxy vinyl unsaturated polyester resin are: density 1.05-1.10 g / cm³. 3 It has a styrene content of 30-36% and a viscosity of 400-550 mPa·s at 25℃.

7. The low-shrinkage, high-corrosion-resistant glass flake coating according to claim 2, characterized in that: The epoxy vinyl unsaturated polyester resin is composed of phenolic epoxy vinyl unsaturated polyester resin.

8. The low-shrinkage, high-corrosion-resistant glass flake coating according to claim 2, characterized in that: The epoxy vinyl unsaturated polyester resin is composed of phenolic epoxy vinyl unsaturated polyester resin and bisphenol A type epoxy vinyl unsaturated polyester resin, and the weight of the bisphenol A type epoxy vinyl unsaturated polyester resin is less than or equal to 30% of the total weight of the epoxy vinyl unsaturated polyester resin.

9. The low-shrinkage, high-corrosion-resistant glass flake coating according to claim 2, characterized in that: The unsaturated polyester reactive diluent is styrene; The acid and alkali resistant powder is one or more of titanium dioxide, barium sulfate, and silicon dioxide; The dispersant is an aliphatic amide compound; The defoamer is a polysiloxane compound; The thixotropic agent is hydrophobic fumed silica.

10. The low-shrinkage, high-corrosion-resistant glass flake coating according to claim 8, characterized in that: The key physicochemical parameters of the bisphenol A type epoxy vinyl unsaturated polyester resin are: solid content 60-65%, acid value 5-15 mgKOH / g, and viscosity at 25℃ 400-550 mPa·s.

11. The method for preparing the low-shrinkage, high-corrosion-resistant glass flake coating according to any one of claims 1-10, characterized in that: The preparation method of the main agent includes the following steps: (1) Preparation of slurry: Take 60-80% of epoxy vinyl unsaturated polyester resin as base material, add fluorinated toughening modifier, dispersant, thixotropic agent, acid and alkali resistant powder, 30-60% of defoamer and 20-40% of unsaturated polyester reactive diluent in the total amount, and stir at high speed of 800-1200 rpm in a stirring tank for 25-35 minutes until the system is uniform to obtain premixed slurry; (2) Dispersion of glass flakes: Adjust the speed of the mixing vessel to 200-400 rpm, and gradually add glass flakes to the premixed slurry while continuously stirring. Then, keep the speed unchanged and continue stirring for 20-30 minutes to make the glass flakes evenly dispersed in the system and form a stable shielding skeleton. (3) Paint preparation: After the glass flakes are evenly dispersed, add the remaining defoamer, the remaining epoxy vinyl unsaturated polyester resin and the remaining unsaturated polyester active diluent. Then, keep the speed constant and continue stirring for 20-30 minutes until the system is uniform, and then filter to obtain the main agent.

12. The method for preparing the low-shrinkage, high-corrosion-resistant glass flake coating according to claim 11, characterized in that: When using, mix the main agent with the peroxide-based curing agent evenly.

Images