Ceramic polymer coating material for water heater inner tank and preparation method and application thereof

Abstract

The invention discloses a ceramic polymer coating material for a water heater inner tank, a preparation method and an application thereof. The coating material comprises the following components by mass percentage: 45% to 55% of a solid epoxy resin composition, 10% to 12% of a solid curing agent composition, 30% to 42% of a filler, 0.1% to 0.4% of a pigment and other additives; based on the mass of the solid epoxy resin composition, the solid epoxy resin composition comprises by mass percentage: 50% to 100% of a modified solid epoxy resin, 0% to 50% of an o-cresol epoxy resin, 0% to 50% of a bisphenol S epoxy resin and 0% to 50% of a bisphenol A type novolac epoxy resin. The coating material is a fusion-bonded epoxy powder coating material, which can operate for a long time at a temperature below 110°C, has good coating bending performance, good temperature resistance, excellent corrosion resistance and outstanding wear resistance.

Description

Technical Field

[0001] The invention relates to the technical field of corrosion protection of water heater inner tanks, and in particular to a ceramic polymer coating material for water heater inner tanks, and a preparation method and application thereof. Background Art

[0002] The safety of a water heater is the first factor that users consider when choosing a water heater. The standard configuration of a water heater is first of all a durable, non-leakage inner tank. In addition to having heat preservation and pressure resistance, the inner tank must also have rust-proof, corrosion-resistant, and waterproof properties. Once the inner tank is corroded and penetrated, it will leak, greatly reducing the safety factor and the water heater will be scrapped.

[0003] The inner tank of the water heater is mostly made of thicker carbon steel plates and enameled on the inner surface to ensure the corrosion resistance of the inner tank and achieve the designed service life. However, the enamel inner tank inevitably has some enamel defects. As the service time increases, the inner tank leaks due to the corrosion of the pores or gaps in the enamel coating. There are also the following reasons that lead to the failure of enamel anti-corrosion protection: First, the enamel coating has the so-called "boiling corrosion phenomenon" at temperatures above 80°C, that is, above this temperature, the enamel coating has accelerated dissolution, and pinhole corrosion occurs, resulting in the failure of local enamel anti-corrosion protection; second, because the enamel coating is a brittle coating, it is sensitive to collision phenomena and is very easy to crack when it is hit, which can also easily lead to the failure of the enamel coating protection; furthermore, the alternation of hot and cold water, especially the uncontrollable water cut-off by the user, causes the "expansion and contraction" of the water heater inner tank, making the protective coating "explosion porcelain", which can also easily lead to the failure of the enamel coating protection.

[0004] The inner tank of the water heater can also be made of stainless steel. Although the inner tank made of stainless steel has good corrosion resistance, the cost of the inner tank is high due to the high price of stainless steel. Moreover, stainless steel is not free from rust. In most corrosive media containing chloride ions or chlorides, any metal or alloy material with an oxidation or passivation film on the surface, such as aluminum alloy, stainless steel, heat-resistant steel, titanium alloy, etc., may suffer from pitting corrosion. Under anodic polarization conditions, as long as the medium contains chloride ions, the metal is prone to pitting corrosion. Especially when there are mechanical cracks, scratches, inclusions or alloy phases, intergranular precipitation, dislocation outcrops and holes on the surface of the passivation film, causing the thickness of the film to be uneven, it is easier to induce local damage to the inner tank. In addition, austenitic stainless steel will also suffer from chromium-poor intergranular corrosion and weld corrosion in the weld corrosion zone.

[0005] Some small companies will use hot-dip galvanized liner, that is, the liner is hot-dip galvanized after forming, and the zinc alloy surface is covered with anti-rust resin. However, this type of liner generally uses ordinary carbon steel, has a thin wall thickness, and is not pressure-resistant, so it is not recommended.

[0006] In recent years, some studies have proposed coated anti-corrosion liner, such as patent CN202020777265.3 "An anti-corrosion liner and a water heater insulation tank having the same" proposed coating the inner wall of the body with a fluororesin anti-corrosion coating. Although polytetrafluoroethylene has the advantages of excellent heat resistance and cold resistance and a low friction coefficient, polytetrafluoroethylene belongs to the 3rd category of carcinogens in the list of carcinogens published by the World Health Organization's International Agency for Research on Cancer. Long-term exposure is bound to endanger human health. Summary of the invention

[0007] In view of the problems existing in the prior art, the present invention provides a ceramic polymer coating material for the inner tank of a water heater, which is designed for a high-temperature wear-resistant inner coating designed for high-temperature conveying media. It can operate for a long time under a temperature condition below 110°C. The coating has good bending performance, good temperature resistance, excellent corrosion resistance and outstanding wear resistance. It is mainly used for the inner coating anti-corrosion standard requirements for high-temperature conveying of different water qualities, and is green and environmentally friendly.

[0008] A ceramic polymer coating material for a water heater inner tank comprises the following components by mass percentage: 45% to 55% (for example, 46%, 48%, 50%, 52%, 54%) of a solid epoxy resin composition, 10% to 12% (for example, 10.5%, 11%, 11.5%) of a solid curing agent composition, 30% to 42% of a filler, 0.1% to 0.4% (for example, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%) of a pigment and other additives.

[0009] The above-mentioned ceramic polymer coating material, as a preferred embodiment, based on the mass of the solid epoxy resin composition, the solid epoxy resin composition includes, by mass percentage: 50% to 100% (for example, 55%, 60%, 70%, 80%, 90%, 95%) of modified solid epoxy resin, 0% to 50% (for example, 5%, 10%, 20%, 30%, 40%, 45%) of o-cresol epoxy resin, 0% to 50% (for example, 5%, 10%, 20%, 30%, 40%, 45%) of bisphenol S epoxy resin and 0% to 50% (for example, 5%, 10%, 20%, 30%, 40%, 45%) of bisphenol A novolac epoxy resin.

[0010] The ceramic polymer coating material is a preferred embodiment, wherein the modified solid epoxy resin is prepared by 100 parts by weight of epoxy resin, 50 to 120 parts by weight of modifier, 0.05 to 5 parts by weight of catalyst, and 25 to 100 parts by weight of curing agent.

[0011] In the present invention, the modified solid epoxy resin is a high glass transition temperature and high toughness modified solid epoxy resin in patent CN 201510181624.2 ("A high glass transition temperature and high toughness modified solid epoxy resin and its preparation method"). The glass transition temperature of the coating prepared by the high glass transition temperature and high toughness modified solid epoxy resin is 128-178°C; the cathode stripping radius is ≤10mm (1.5V, 95±3°C, 28d); there is no crack after -30°C, 3° bending test; the softening point is 96-115°C; the epoxy value is 0.19-0.275mol / 100g; and the functionality is 2.6.

[0012] In the present invention, the softening point of the o-cresol epoxy resin is 90°C to 105°C, and it is a heat-resistant epoxy resin. The o-cresol epoxy resin is a linear phenolic heat-resistant multifunctional epoxy resin, each benzene ring is connected with an epoxy group, and the resin can provide 2.5 times of cross-linking points when solidified, and it is very easy to form a three-dimensional structure with a high cross-linking density. In addition, the solidified material is rich in phenolic skeletons, and exhibits excellent thermal stability, mechanical strength, electrical insulation performance, water resistance, chemical resistance, and a high glass transition temperature (Tg), but the resin is brittle after solidification.

[0013] The multifunctional bisphenol A novolac epoxy resin has the properties of both phenolic and epoxy. Since the novolac epoxy resin structure contains more than two epoxy groups and introduces more aromatic rings with good thermal stability, the crosslinking density after curing is high and the glass transition temperature (Tg) of the product is high. At the same time, the epoxy functionality is high, and many crosslinking points can be provided, which is easy to form a highly crosslinked three-dimensional structure. Its cured product shows excellent mechanical strength, electrical insulation performance, water resistance, chemical resistance, high glass transition temperature and thermal stability. Preferably, in the present invention, the softening point of the bisphenol A novolac epoxy resin is 98-110°C, the epoxy value is 0.08-0.12mol / 100g, and the volatile matter is ≤0.5%.

[0014] In the present invention, the softening point of the bisphenol S epoxy resin is 90°C to 115°C. Bisphenol S epoxy resin has better flexural strength, compressive strength and thermal stability than traditional bisphenol A epoxy resin due to the introduction of -SO2- polar group. Bisphenol S epoxy resin has high heat resistance, and its heat deformation temperature is 60°C to 70°C higher than that of bisphenol A epoxy resin. Even if 1 part (1%) of BPSER is added, the T g Increase 10℃. The highly polar sulfone group replaces the isopropyl group of bisphenol A epoxy resin, improving the heat resistance and thermal stability of the resin. The sulfone group also improves the bonding force and increases the ring-opening activity of the epoxy group; the thermal stability is good, with a weight loss of less than 5% at 260℃ / 200h and a weight loss of less than 2% at 200℃ / 2000h.

[0015] After adding curing agent to bisphenol S epoxy resin, the gel and curing speed is fast. The cured product has stable dimensions and good solvent resistance. It has excellent heat resistance, adhesion, high impact strength and fast curing speed.

[0016] The modified solid epoxy resin gives the coating high flexibility, resistance to cathode stripping and high temperature resistance, while the o-cresol epoxy resin and bisphenol A novolac epoxy resin give the coating better mechanical strength, high temperature resistance and thermal stability.

[0017] The above-mentioned ceramic polymer coating material, as a preferred embodiment, based on the mass of the solid curing agent composition, the solid curing agent composition includes, by mass percentage: 50% to 100% (for example, 55%, 60%, 70%, 80%, 90%, 95%) of Amanda9808M2 modified hydroxyl-terminated phenol curing agent, 0% to 50% of Amanda 9887M modified phenol trifunctional curing agent and 0% to 50% (for example, 5%, 10%, 20%, 30%, 40%, 45%) of Amanda 879X modified phenol trifunctional curing agent.

[0018] The Amanda9808M2 is a modified multifunctional epoxy curing agent, suitable for special powder coatings resistant to high temperatures under harsh conditions, such as special powder coatings for drill pipe and oil pipe internal protection, with excellent corrosion resistance and high permeability resistance. The coating has excellent chemical resistance, solvent resistance, high hardness, good leveling, long gel time, and high glass transition temperature. It is a product produced and sold by Daqing Qinglu Langrun Technology Co., Ltd.

[0019] The Amanda 9887M modified phenolic trifunctional curing agent has light yellow particles, a hydroxyl value of 0.80-0.90 mol / 100g, and a softening point of 90-100°C. After being cured with epoxy resin to form a film, the coating has excellent corrosion resistance and high permeability resistance, high hardness, good leveling, long gel time, and high glass transition temperature. It is a product produced and sold by Daqing Qinglu Langrun Technology Co., Ltd.

[0020] Modified phenolic curing agent Amanda 879X, contains three functional groups (hydroxyl, carbonyl, amine), does not contain accelerators, and is resistant to high-temperature cathode stripping: 3.5-4mm (65℃±3℃, 30 days, 1.5V). It has excellent miscibility with ordinary bisphenol A or phenolic modified epoxy resin, has extremely high reactivity, can be cured quickly, and the coating has excellent chemical resistance, solvent resistance, high-temperature cathode stripping resistance, leveling and adhesion, flexibility, impact resistance and other mechanical properties. The modified phenolic curing agent Amanda879X used here is a product produced and sold by Daqing Qinglu Langrun Technology Co., Ltd.

[0021] Amanda9808M2 modified hydroxyl-terminated phenol curing agent can make the coating obtain enough hydroxyl groups, thus giving the coating excellent adhesion. The multi-functional structure makes the coating have a high cross-linking density, which gives the coating good corrosion resistance and high anti-penetration performance. The addition of modified phenol curing agent Amanda 879X further increases the reactivity of the curing agent, which can give the coating more excellent mechanical strength, anti-penetration performance and better adhesion.

[0022] The curing agent reacts with the resin to cause three-dimensional cross-linking of the molecular structure to obtain a cured product with a three-dimensional network interlaced structure.

[0023] The curing mechanism of the curing agent of the present invention on epoxy resin mainly includes: etherification reaction of phenolic hydroxyl group and epoxy group, etherification reaction of secondary hydroxyl group and epoxy group, tertiary amine catalyzed self-polymerization reaction of epoxy and 2-methylimidazole causing ring-opening reaction of epoxy, etc. The resin and the curing agent undergo chemical crosslinking: as the chemical crosslinking density increases, the degree of restriction of molecular chain activity also increases, the average chain length of adjacent crosslinking points becomes smaller, the flexibility decreases, and the Tg increases. A high Tg indicates that the crosslinking density of the system is large and the thermal stability is high, thereby improving the heat resistance of the system. At the same time, as the crosslinking density increases, the chemical resistance of the system also increases accordingly.

[0024] The above-mentioned ceramic polymer coating material, as a preferred embodiment, based on the mass of the ceramic polymer coating material for the water heater inner tank, the filler includes 3% to 5% (for example, 2.5%, 3%, 3.5%, 4%, 4.5%) of ultrafine precipitated barium sulfate, 10% to 15% (for example, 10.5%, 11%, 12%, 13%, 14%) of mica powder, 16% to 20% (for example, 15%, 16%, 17%, 18%, 18.8%) of ceramic fiber powder and 1% to 2% (for example, 1.1%, 1.3%, 1.5%, 1.8%) of nano ceramic powder.

[0025] Preferably, the fiber aspect ratio of the mica powder is (10-12):1 (for example, 10.5:1, 11:1, 11.5:1), the fiber aspect ratio of the ceramic fiber powder is (10-12):1 (for example, 10.5:1, 11:1, 11.5:1), and is pretreated with silane coupling agent HK560.

[0026] In the present invention, the application of ultrafine precipitated barium sulfate in powder coating can improve the smoothness, leveling and mechanical strength of the coating, and improve the hiding power, fluidity and dispersibility of the coating. In the present invention, the addition amount of ultrafine precipitated barium sulfate is 3% to 5%. Too much will reduce the toughness of the coating, and too little will fail to achieve the expected smoothness, leveling and mechanical strength effects. Too much or too little will affect the density of the coating.

[0027] Mica powder has excellent heat resistance, acid resistance, alkali resistance and excellent electrical insulation. It can improve rigidity, heat resistance and insulation in anti-corrosion powder. Some data show that mica powder also has certain aging resistance. In the present invention, the amount of mica powder added is 10% to 15%. Too much will affect the leveling of the coating, reduce the toughness of the coating, and affect the gloss of the coating. Too little will make the heat resistance, acid and alkali resistance and mechanical strength of the coating worse. Too much or too little will affect the density of the coating.

[0028] The ceramic fiber powder has a fiber aspect ratio of 10 to 12:1, preferably silicon carbide fiber and zirconium oxide fiber, which have the characteristics of high temperature resistance, high modulus and high strength, high strength, good thermal shock resistance, chemical corrosion resistance, etc., and also has the antioxidant function that organic fibers cannot match. It needs to be pretreated with silane coupling agent HK560 when used. In the present invention, the addition amount of ceramic fiber powder is 16% to 20% (for example, 15%, 16%, 17%, 18%, 18.8%). Too much will reduce the toughness of the coating and affect the leveling of the coating, and too little will affect the temperature resistance and mechanical strength of the coating.

[0029] Nano ceramic powder has the properties and functions of high strength, high and low temperature resistance, non-flammability, corrosion resistance, compression resistance, light weight, sound insulation and heat insulation due to its unique internal and surface structure. In the present invention, the addition amount of nano ceramic powder is 1% to 2% (for example, 1.1%, 1.3%, 1.5%, 1.8%). Too much will reduce the toughness of the coating, affect the glossiness and leveling of the coating, and too little will reduce the mechanical strength and temperature resistance of the coating.

[0030] As a preferred embodiment of the ceramic polymer coating material, the other additives are composed of a promoter, a leveling agent, a loose flow dispersant and a degassing agent.

[0031] The above-mentioned ceramic polymer coating material, as a preferred embodiment, based on the mass of the ceramic polymer coating material for the water heater tank, the other additives include, by mass percentage, accelerator 0.1% to 1% (for example, 0.12%, 0.15%, 0.18%, 0.2%), leveling agent 1% to 2% (for example, 1.05%, 1.1%, 1.15%, 1.18%, 1.2%), loose flow dispersant 0.1% to 1% (for example, 0.12%, 0.15%, 0.2%, 0.25%, 0.3%, 0.4%) and deaerator 0.1% to 1% (for example, 0.12%, 0.15%, 0.2%, 0.25%, 0.3%, 0.4%, 0.5%).

[0032] As a preferred embodiment of the ceramic polymer coating material, the accelerator is 2-methylimidazole epoxy adduct T-50SB, the leveling agent is silicone acrylic acid, the loose flow dispersant is fumed silica, and the degassing agent is benzoin.

[0033] 2-Methylimidazole epoxy adduct T-50SB is a product produced and sold by Daqing Qinglu Langrun Technology Co., Ltd. It has stable performance and wide application, and is particularly suitable for low-temperature curing (120°C) or fast-curing epoxy powder curing agent. It has excellent compatibility with resins in both extrusion and hot-melt mixing processes, making the surface of the cured coating smooth and flat with superior comprehensive performance. It is widely used in the preparation of thin-coat decorative or functional epoxy powder coatings in catalytic dicyandiamide curing systems.

[0034] Silicone acrylic leveling agents are commercially available products, with no restrictions on manufacturers or brands.

[0035] In the present invention, the ceramic polymer coating material is a powder coating material.

[0036] The present invention also provides a method for preparing the ceramic polymer coating material for the water heater inner tank, which adopts the following technical scheme:

[0037] A method for preparing the ceramic polymer coating material for the water heater inner tank comprises:

[0038] According to the above formula, the solid epoxy resin composition, solid curing agent composition, pigment, filler and other additives are fully mixed and then melt-kneaded and extruded to obtain an extrudate; the extrudate is ground and sieved to a specified particle size to obtain a powder coating material.

[0039] In the above preparation method, as a preferred embodiment, the mixing is carried out in a high-speed mixer. Preferably, when mixing twice, the first mixing time and the second mixing time are 3 to 3.5 minutes respectively; preferably, when mixing three times, the first and third mixing times are 3 to 3.5 minutes respectively, and the second mixing time is 1.5 to 2 minutes.

[0040] In the above preparation method, as a preferred embodiment, the melt-mixing extrusion is carried out in a screw extruder to obtain an extrudate; wherein the temperature of zone 1 of the extruder is 95-100°C (for example, 96°C, 97°C, 98°C), the temperature of zone 2 is 85-90°C (for example, 86°C, 87°C, 88°C), and the rotation speed is 280-310r / min (for example, 285r / min, 290r / min, 300r / min, 305r / min), preferably 300r / min.

[0041] In the above preparation method, as a preferred embodiment, the extrudate is ground in an ACM grinder and then sieved through a 120-160 mesh sieve to reach a specified particle size.

[0042] The present invention also provides a water heater liner, comprising a liner substrate and the above-mentioned ceramic polymer coating material attached to the inner wall of the liner substrate. That is, the present invention provides an application of the above-mentioned ceramic polymer coating material, wherein the ceramic polymer coating material is coated on the inner wall of the water heater liner substrate to form a coating, so that the water heater can deliver high-temperature water.

[0043] The material of the inner liner matrix of the present invention can be ordinary steel, such as carbon steel, ND steel, H10 steel and other conventional steels.

[0044] In the above water heater inner tank, the thickness of the coating formed by coating the ceramic polymer coating material on the inner wall of the water heater inner tank substrate is 200-350 μm.

[0045] The present invention also provides a method for preparing the water heater inner tank, comprising the following steps:

[0046] (1) Surface treatment of the water heater liner substrate, preferably under the condition of an operating environment of 20-35°C and a relative humidity of less than 90% (e.g., 50%, 60%, 70%, 80%, 85%), sandblasting the inner wall of the water heater liner substrate to remove rust, the rust removal grade should reach Sa2.5-3, the anchor pattern depth should be 40-75 μm (e.g., 45 μm, 50 μm, 60 μm, 65 μm, 70 μm), and high-pressure air should be used to blow the inner wall of the water heater liner until there is no dust or other attachments on the surface;

[0047] (2) Preheating: preheating the water heater liner matrix, preferably at a temperature of 200±3°C (i.e., 197-203°C), and more preferably preheating for 40-60 minutes; more preferably, placing the water heater liner matrix in a heating box for preheating;

[0048] (3) Preparation of coating: spray the ceramic polymer coating material onto the inner surface of the water heater inner tank substrate to a coating thickness of 200 to 350 μm (e.g., 220 μm, 250 μm, 270 μm, 300 μm, 320 μm, 340 μm), and return the water heater inner tank sprayed with the coating material to a furnace for curing; preferably, the curing is performed for 30 to 120 minutes; preferably, the spraying is performed using an electrostatic spraying device; preferably, the water heater inner tank sprayed with the coating material is placed in a heating box and returned to a furnace for curing at a temperature of 230 to 235°C.

[0049] The coating of the water heater inner tank obtained by the above-mentioned preparation method of the water heater inner tank can achieve the following technical indicators (the indicators are set according to the use conditions of the water heater inner tank):

[0050] After being boiled in 3.5% sodium chloride salt water at 95℃±3℃ water bath for 28 days, the adhesion is 0~1 level; refer to Appendix H of GB / T39636-2020 Technical Specification for External Coating of Steel Pipeline Fusion Epoxy Powder;

[0051] Cathodic stripping resistance: 90℃±3℃, 48h, -1.5V, CD≤15mm; refer to CSAZ245.20Series-10-2010;

[0052] Wear resistance: (1000g / 1000r, CS-17), ≤20mg; refer to GB / T 39636-2020 Technical Specification for External Coating of Fusion-bonded Epoxy Powder for Steel Pipes;

[0053] Bending resistance, 23±3℃, 1h, after 1.5° bending, the coating is intact. Refer to GB / T31361-2015 Solvent-free epoxy liquid coatings, the first category of anti-corrosion coatings, for the testing indicators of the bending resistance of ordinary coatings.

[0054] The ceramic polymer coating material for the inner tank of a water heater provided by the present invention is a sintered epoxy powder coating material.

[0055] Compared with the prior art, the present invention has the following technical effects:

[0056] The ceramic polymer coating material for the water heater tank of the present invention is a sintered epoxy powder coating material, which is designed for a high-temperature wear-resistant inner coating designed for high-temperature conveying media. It can operate for a long time under a temperature condition below 110°C. The coating has good bending performance, good temperature resistance, excellent corrosion resistance and outstanding wear resistance. It is mainly used for conveying high-temperature water. The inner coating of the water heater tank meets the anti-corrosion standard requirements and is green and environmentally friendly. DETAILED DESCRIPTION

[0057] The present invention will be described in detail below in conjunction with the embodiments. Each example is provided by way of explanation of the present invention and does not limit the present invention. In fact, it will be clear to those skilled in the art that modifications and variations may be made in the present invention without departing from the scope or spirit of the present invention. For example, a feature shown or described as a part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desired that the present invention includes such modifications and variations within the scope of the appended claims and their equivalents.

[0058] In the present invention, the modified solid epoxy resin Amanda1177HTM (V), the o-cresol epoxy resin Amanda1162, the bisphenol S epoxy resin Amanda1158ES; the Amanda9808M2 modified hydroxyl-terminated phenol curing agent, Amanda 9887M and Amanda 879X modified phenol trifunctional curing agents are products produced and sold by Daqing Qinglu Langrun Technology Co., Ltd., and other raw materials can be purchased from the market.

[0059] If not otherwise specified, the modified solid epoxy resin in the present invention adopts the patent product of Daqing Qinglu Langrun Technology Co., Ltd. (CN 201510181624.2, "A high glass transition temperature and high toughness modified solid epoxy resin and its preparation method"): high glass transition temperature and high toughness modified solid epoxy resin.

[0060] The present invention provides a ceramic polymer coating material for a water heater inner tank, which is composed of the following components by mass percentage:

[0061]

[0062] The sum of the percentages of the components in the ceramic polymer coating material for the inner tank of the water heater is 100%.

[0063] in,

[0064] The solid epoxy resin composition is as follows by mass percentage:

[0065] High glass transition temperature and high toughness modified solid epoxy resin 50% to 100%, high softening point (90°C to 105°C) o-cresol epoxy resin 0% to 50%, high softening point (90°C to 115°C) bisphenol S epoxy resin 0% to 50%, high softening point (90°C to 105°C) bisphenol A novolac epoxy resin 0% to 50%.

[0066] The solid curing agent composition is as follows by mass percentage:

[0067] Based on the mass of the solid curing agent composition, the solid curing agent composition comprises, by mass percentage, 50% to 100% of Amanda9808M2 modified hydroxyl-terminated phenol curing agent, 0% to 50% of Amanda9887M modified phenol trifunctional curing agent, and 0% to 50% of Amanda 879X modified phenol trifunctional curing agent;

[0068] Ceramic fiber powder (fiber aspect ratio 10-12:1) was pretreated with silane coupling agent HK560.

[0069] Example 1

[0070] A ceramic polymer coating material for a water heater inner tank, comprising the following components by mass percentage:

[0071]

[0072] The solid epoxy resin composition is a modified solid epoxy resin with high glass transition temperature and high toughness;

[0073] The solid curing agent composition is Amanda9808M2 modified hydroxyl-terminated phenol curing agent;

[0074] The ceramic fiber powder is pretreated with silane coupling agent HK560.

[0075] Example 2

[0076] A ceramic polymer coating material for a water heater inner tank, comprising the following components by mass percentage:

[0077]

[0078]

[0079] Based on the mass of the solid epoxy resin composition, the solid epoxy resin composition is composed of 50% of a high glass transition temperature and high toughness modified solid epoxy resin, 25% of an o-cresol epoxy resin with a high softening point (90°C to 105°C), 20% of a bisphenol S epoxy resin with a high softening point (90°C to 115°C), and 5% of a bisphenol A novolac epoxy resin with a high softening point (90°C to 105°C).

[0080] Based on the mass of the solid curing agent composition, the solid curing agent composition is composed of 70% of Amanda9808M2 modified hydroxyl-terminated phenol curing agent; 20% of Amanda 9887M modified phenol trifunctional curing agent; and 10% of Amanda 879X modified phenol trifunctional curing agent by mass percentage;

[0081] The ceramic fiber powder is pretreated with silane coupling agent HK560.

[0082] Example 3

[0083] A ceramic polymer coating material for a water heater inner tank, comprising the following components by mass percentage:

[0084]

[0085] in,

[0086] Based on the mass of the solid epoxy resin composition, the solid epoxy resin composition is composed of 70% of a high glass transition temperature and high toughness modified solid epoxy resin, 15% of an o-cresol epoxy resin with a high softening point (90°C to 105°C), 10% of a bisphenol S epoxy resin with a high softening point (90°C to 115°C) and 5% of a bisphenol A novolac epoxy resin with a high softening point (90°C to 105°C) by mass percentage;

[0087] Based on the mass of the solid curing agent composition, the solid curing agent composition is composed of 60% of Amanda9808M2 modified hydroxyl-terminated phenol curing agent, 35% of Amanda 9887M modified phenol trifunctional curing agent, and 5% of Amanda 879X modified phenol trifunctional curing agent, by mass percentage.

[0088] The ceramic fiber powder is pretreated with silane coupling agent HK560.

[0089] Application examples of ceramic polymer coating materials for water heater tanks

[0090] The ceramic polymer coating material for the water heater inner tank prepared in Examples 1-3 is applied to the water heater inner tank, using the following technical solution:

[0091] (1) Surface treatment of water heater inner tank: In the operating environment of room temperature of 20-35℃ and relative humidity less than 90%, the inner wall of the water heater inner tank is sandblasted to remove rust. The rust removal level should reach Sa2.5-3 level, and the anchor pattern depth should be 40-75μm. High-pressure air is used to blow the inner wall of the water heater inner tank until there is no dust or other attachments on the surface;

[0092] (2) Preheating: Place the inner tank of the water heater in a 200°C heating box and preheat for 40 minutes;

[0093] (3) Coating preparation: The powder coating material is sprayed with an electrostatic spraying device to a coating thickness of 200 to 350 μm, and the water heater tank is placed in a heating box at 235° C. and cured for 100 minutes to prepare the water heater tank coating.

[0094] The ceramic polymer coating materials prepared in Examples 1-3 are applied to the inner tank of a water heater, and the obtained inner tank coatings of the water heater can respectively achieve the following technical indicators:

[0095] After being boiled in 3.5% sodium chloride salt water at 95℃±3℃ water bath for 28 days, the adhesion is level 1, level 1, and level 1 (refer to Appendix H of GB / T 39636-2020 Technical Specification for External Coating of Steel Pipeline Fusion-bonded Epoxy Powder);

[0096] Cathodic stripping resistance: 90℃±3℃, 48h, -1.5V, CD=10.5mm, 8mm, 9mm; refer to CSAZ245.20Series-10-2010;

[0097] Wear resistance: (1000g / 1000r, CS-17), 12mg / 10mg / 8mg; refer to GB / T39636-2020 Technical Specification for External Coating of Fusion-bonded Epoxy Powder for Steel Pipes;

[0098] Bending resistance, 23±3℃, 1h, after 1.5° bending, the coating is intact. Refer to GB / T31361-2015 Solvent-free epoxy liquid coatings, the first category of anti-corrosion coatings, for the testing indicators of the bending resistance of ordinary coatings.

[0099] In addition, when the ceramic polymer coating materials of Examples 1-3 are applied to the inner tank of a water heater, the obtained inner tank coatings of the water heater all have other coating technical indicators as shown in Table 1.

[0100] Table 1 Other coating technical indicators of ceramic polymer coating materials of Examples 1-3 applied to water heater tanks

[0101]

Claims

1. A ceramic polymer coating material for a water heater inner tank, comprising the following components by mass percentage: 45% to 55% of a solid epoxy resin composition, 10% to 12% of a solid curing agent composition, 30% to 42% of a filler, 0.1% to 0.4% of a pigment, and other additives; Based on the mass of the solid epoxy resin composition, the solid epoxy resin composition comprises, by mass percentage: 50% to 100% of modified solid epoxy resin, 0% to 50% of o-cresol epoxy resin, 0% to 50% of bisphenol S epoxy resin and 0% to 50% of bisphenol A novolac epoxy resin; The modified solid epoxy resin is prepared by 100 parts by weight of epoxy resin, 50 to 120 parts by weight of modifier, 0.05 to 5 parts by weight of catalyst, and 25 to 100 parts by weight of curing agent; The modified solid epoxy resin has a softening point of 96-115°C; an epoxy value of 0.19-0.275 mol / 100g; a functionality of 2.6; the softening point of the o-cresol epoxy resin is 90-105°C; the softening point of the bisphenol S epoxy resin is 90-115°C; the softening point of the bisphenol A novolac epoxy resin is 98-110°C, the epoxy value is 0.08-0.12 mol / 100g, and the volatile matter is ≤0.5%; Based on the mass of the solid curing agent composition, the solid curing agent composition includes, by mass percentage: 50% to 100% of Amanda9808M2 modified hydroxyl-terminated phenol curing agent, 0% to 50% of Amanda 9887M modified phenol trifunctional curing agent, and 0% to 50% of Amanda 879X modified phenol trifunctional curing agent; Based on the mass of the ceramic polymer coating material for the water heater inner tank, the filler includes 3% to 5% of ultrafine precipitated barium sulfate, 10% to 15% of mica powder, 16% to 20% of ceramic fiber powder and 1% to 2% of nano ceramic powder in terms of mass percentage; The fiber aspect ratio of the ceramic fiber powder is (10-12):1, and the ceramic fiber powder is pretreated with a silane coupling agent HK560.

2. The ceramic polymer coating material for water heater inner tank according to claim 1, characterized in that: The other additives are composed of accelerators, leveling agents, loose flow dispersants and deaerators.

3. The ceramic polymer coating material for water heater inner tank according to claim 2, characterized in that: The fiber aspect ratio of the mica powder is (10-12): 1; and / or, Based on the mass of the ceramic polymer coating material for the water heater inner tank, the other additives include, by mass percentage, 0.1% to 1% of an accelerator, 1% to 2% of a leveling agent, 0.1% to 1% of a loose flow dispersant, and 0.1% to 1% of a deaerator.

4. The ceramic polymer coating material for water heater inner tank according to claim 3, characterized in that: The accelerator is 2-methylimidazole epoxy adduct T-50SB, the leveling agent is silicone acrylic acid, the loose flow dispersant is fumed silica, and the degassing agent is benzoin.

5. A method for preparing a ceramic polymer coating material for a water heater tank according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: The solid epoxy resin composition, solid curing agent composition, pigment, filler and other additives are fully mixed and then melt-kneaded and extruded to obtain an extrudate; the extrudate is ground and sieved to a specified particle size to obtain a powder coating material.

6. The method for preparing a ceramic polymer coating material for a water heater tank according to claim 5, characterized in that: The mixing is carried out in a high-speed mixer, and / or, The melt-mixing extrusion is carried out in a screw extruder to obtain an extrudate; and / or, The extrudate was ground in an ACM mill and then sieved through a 120-160 mesh sieve to achieve a specified particle size.

7. The method for preparing a ceramic polymer coating material for a water heater tank according to claim 6, characterized in that: When mixing twice, the first mixing time and the second mixing time are 3 to 3.5 min respectively; when mixing 3 times, the first and third mixing times are 3 to 3.5 min respectively, and the second mixing time is 1.5 to 2 min.

8. The method for preparing a ceramic polymer coating material for a water heater tank according to claim 6, characterized in that: The temperature of extruder zone 1 is 95-100°C, the temperature of zone 2 is 85-90°C, and the speed is 280-310 r / min.

9. A water heater tank, characterized in that: The water heater inner tank comprises an inner tank matrix and a ceramic polymer coating material for a water heater inner tank according to any one of claims 1 to 4 attached to the inner wall of the inner tank matrix.

10. The water heater inner tank according to claim 9, characterized in that: The thickness of the ceramic polymer coating material is 200-350 μm.

11. A method for preparing a water heater tank according to claim 9 or 10, characterized in that the method comprises the following steps: (1) Surface treatment of the inner tank of the water heater: sandblast the inner wall of the inner tank of the water heater to remove rust. The rust removal level should reach Sa2.5~3, and the anchor pattern depth should be 40~75μm. Use high-pressure air to blow the inner wall of the inner tank of the water heater until there is no dust attached to the surface; (2) Preheating: preheating the inner tank of the water heater; (3) Coating preparation: spray the ceramic polymer coating material for the water heater inner tank according to any one of claims 1 to 4 onto the inner surface of the water heater inner tank substrate to a coating thickness of 200 to 350 μm, place the water heater inner tank sprayed with the coating material into a heating box, and return it to the furnace for curing at a temperature of 230 to 235°C.

12. A method for preparing a water heater tank according to claim 9 or 10, characterized in that the method comprises the following steps: (1) Surface treatment of the water heater liner substrate: sandblast the inner wall of the water heater liner substrate to remove rust in an operating environment of 20~35℃ and relative humidity less than 90%. The rust removal grade should reach Sa2.5~3, and the anchor pattern depth should be 40~75μm. Use high-pressure air to blow the inner wall of the water heater liner until there is no dust attached to the surface; (2) Preheating: Preheat the inner tank of the water heater at a temperature of 200±3℃; (3) Coating preparation: spray the ceramic polymer coating material for the water heater inner tank according to any one of claims 1 to 4 onto the inner surface of the water heater inner tank substrate to a coating thickness of 200 to 350 μm, place the water heater inner tank sprayed with the coating material into a heating box, and return it to the furnace for curing at a temperature of 230 to 235°C.

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