Process for the preparation of a spherical alumina-cordierite composite refractory coating composition

Abstract

The present application relates to the technical field of paint, and discloses a preparation method of a spherical alumina-cordierite composite refractory paint composition, wherein 100 parts by weight of epoxy resin, 1-5 parts by weight of an amino-terminated polymer ultraviolet absorber, 15-28 parts by weight of a filler spherical alumina trihydrate and cordierite, 29-32 parts by weight of a curing agent and the like are stirred and uniformly mixed to obtain the spherical alumina-cordierite composite refractory paint composition.The polymer ultraviolet absorber contains an ortho-hydroxybenzotriazole group, which can improve the ultraviolet absorption characteristics and ultraviolet aging resistance of the paint.The polymer, as an absorber, contains a biphenyl structure with thermal stability, which is beneficial to improving the thermal decomposition temperature, heat resistance and water resistance after being co-cured with the epoxy resin.The addition of the spherical alumina trihydrate and cordierite improves the limiting oxygen index of the paint coating and improves the flame-retardant fire resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of paint, in particular to a preparation method of spherical alumina-cordierite composite refractory coating composition. BACKGROUND

[0002] Epoxy resin coating has good corrosion resistance, heat preservation and other properties, and is widely used. Traditional epoxy resin has poor ultraviolet aging resistance, poor heat resistance and poor fire resistance. Alumina has high mechanical strength, high hardness and certain fire resistance, and is widely used in materials such as epoxy resin. Cordierite is a silicate mineral with good fire resistance and low high-temperature expansion rate, and is mainly used in refractory materials. Adding ultraviolet absorbers, flame retardants and other additives to epoxy resin coating can improve its ultraviolet aging resistance, weather resistance, fire resistance and other properties.

[0003] Traditional ultraviolet absorbers for coatings include benzophenone, benzotriazole and the like. Chinese patent application CN118580465A discloses an ultraviolet-resistant modified epoxy resin and a preparation method thereof, which uses epoxy resin, hydroxyethyl methacrylate, 2-(2'-hydroxy-5'-methylphenyl) benzotriazole, gamma-aminopropyl triethoxysilane and the like as raw materials to prepare a modified epoxy resin with good ultraviolet resistance. However, compared with small molecule ultraviolet absorbers, macromolecular polymer ultraviolet absorbers have better heat resistance, excellent compatibility with high molecular resin matrix and less influence on the mechanical properties of the material. The present application aims to improve the ultraviolet resistance, weather resistance, waterproofness, heat resistance and fire resistance of epoxy resin coating by using amino-terminated polymer ultraviolet absorbers, alumina and cordierite. SUMMARY

[0004] The technical problem solved by the present application is to improve the ultraviolet resistance, weather resistance, waterproofness, heat resistance and fire resistance of epoxy resin coating.

[0005] The technical solution of the present application is a preparation method of spherical alumina-cordierite composite refractory coating composition.

[0006] Step S1, 2-[2'-hydroxy-3'-(diethylenetriamine) acetyl-5'-methylphenyl] benzotriazole and diphenyl formaldehyde are added to dimethyl sulfoxide, and the reaction is carried out in a nitrogen atmosphere, then 2-[2'-hydroxy-3'-(diethylenetriamine) acetyl-5'-methylphenyl] benzotriazole is added, and the reaction is carried out at 80-110℃ for 12-18h, then the solution is poured into ethanol, filtered and washed with ethanol, and dried to obtain an amino-terminated polymer ultraviolet absorber. The reaction formula is:

[0007]

[0008] Step S2, 100 parts by weight of epoxy resin, 1-5 parts by weight of terminal amino polymer ultraviolet absorber, 0.5-1 parts by weight of defoaming agent, 0.4-0.8 parts by weight of leveling agent, 1.2-1.7 parts by weight of dispersing agent, 15-28 parts by weight of filler, 29-32 parts by weight of curing agent, stirring and mixing to obtain spherical alumina-cordierite composite refractory coating composition.

[0009] Preferably, the curing agent is a polyether amine curing agent.

[0010] Preferably, the molar ratio of 2-[2'-hydroxy-3'-(diethylene triamine) acetyl-5'-methyl phenyl] benzotriazole to biphenyl dimethyl formaldehyde in step S1 is (1.05-1.1):1.

[0011] Preferably, the preparation method of 2-[2'-hydroxy-3'-(diethylene triamine) acetyl-5'-methyl phenyl] benzotriazole is:

[0012] Step (1) adding 2-(2'-hydroxy-3'-chloroacetyl-5'-methyl phenyl) benzotriazole, 1,7-bis-BOC-1,4,7-triazepane, potassium carbonate to the solvent, stirring at 35-60℃ for 12-24h, distilling the solution under reduced pressure, washing with water, then recrystallizing and purifying in ethanol to obtain the benzotriazole precursor.

[0013] Step (2) adding the benzotriazole precursor to the hydrogen chloride ethyl acetate solution, reacting at room temperature for 4-5h, adding sodium bicarbonate solution, oscillating and then standing to separate the layers, removing the lower aqueous phase, drying the upper ethyl acetate extraction phase with anhydrous sodium sulfate, filtering the filtrate under reduced pressure, and recrystallizing and purifying the product in ethanol to obtain 2-[2'-hydroxy-3'-(diethylene triamine) acetyl-5'-methyl phenyl] benzotriazole. The reaction formula is:

[0014]

[0015] Preferably, the solvent in step (1) is any one or combination of acetonitrile, tetrahydrofuran, and water.

[0016] Preferably, the molar ratio of 2-(2'-hydroxy-3'-chloroacetyl-5'-methyl phenyl) benzotriazole, 1,7-bis-BOC-1,4,7-triazepane, potassium carbonate in step (1) is (1.1-1.3):1:(1.1-1.5).

[0017] The technical effect of the present application: the present application adds an amino-terminated polymer ultraviolet absorber to the epoxy resin coating, which contains an amino-terminated group, can replace part of the polyether amine curing agent, and has a co-curing reaction with the epoxy resin to improve the curing and crosslinking properties of the epoxy resin, avoid the influence of the mechanical properties of the coating film due to insufficient addition of the curing agent, and make the coating film have higher impact resistance.

[0018] The polymer ultraviolet absorber of the present application contains an ortho-hydroxybenzotriazole group, which can convert ultraviolet light energy into chemical energy and heat energy, thereby improving the ultraviolet absorption properties of the coating film and exhibiting excellent anti-ultraviolet aging performance.

[0019] The ultraviolet absorber of the present application is a heat-resistant macromolecular polymer, and the molecular main chain contains a heat-stable biphenyl structure, which is beneficial to improving the heat resistance of the coating film after co-curing with the epoxy resin, and exhibits higher thermal decomposition temperature. After co-curing with the epoxy resin, the epoxy resin molecular chain is tightly crosslinked, and the biphenyl structure has hydrophobicity, which can inhibit the entry of water molecules into the film interior, thereby improving the water resistance and waterproof performance. It has good practical application in weather-resistant fire-resistant waterproof coatings and the like.

[0020] The limiting oxygen index of traditional epoxy resin and its coating is only about 18%, and the present application adds spherical aluminum oxide trihydrate and cordierite to the coating, the spherical aluminum oxide trihydrate can play a role in flame retardation and smoke suppression, and the cordierite has high fire resistance and low high-temperature expansion rate, the combination of the two improves the limiting oxygen index of the coating layer to 21.6-24.3%, and improves the flame-retardant and fire-resistant performance of the coating. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present application more clear, the technical scheme of the present application will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0022] 2-(2'-hydroxy-3'-chloroacetyl-5'-methylphenyl)benzotriazole is prepared according to the method of the journal "Daily Chemical Industry", Vol. 39, No. 3, June 2009, document "Synthesis of reactive chloroacetyl benzotriazole ultraviolet absorber". The structural formula is

[0023] Example 1:

[0024] (1) To 25 mL of tetrahydrofuran, 10 mL of water, 26 mmol of 2-(2'-hydroxy-3'- chloroacetyl-5'-methylphenyl) benzotriazole, 20 mmol of 1,7-bis-BOC-1,4,7- triazepane, 30 mmol of potassium carbonate were added, and stirred at 35°C for 24 h, the solution was distilled under reduced pressure, washed with water, and then purified by recrystallization in ethanol to obtain a benzotriazole precursor.

[0025] (2) To 30 mL of ethyl acetate solution of hydrogen chloride with a concentration of 1 mol / L, 3 g of benzotriazole precursor was added, and reacted at room temperature for 4 h, sodium bicarbonate solution was added, and after shaking, the lower aqueous phase was removed, and the upper ethyl acetate extraction phase was dried with anhydrous sodium sulfate, and after filtration, the filtrate was distilled under reduced pressure, and the product was purified by recrystallization in ethanol to obtain 2-[2'-hydroxy-3'-(divinyltriamine) acetyl-5'-methylphenyl] benzotriazole.

[0026] (3) To 50 mL of dimethyl sulfoxide, 10 mmol of 2-[2'-hydroxy-3'-(divinyltriamine) acetyl-5'-methylphenyl] benzotriazole, 10 mmol of biphenyl dimethyl formaldehyde were added, and reacted in a nitrogen atmosphere, and then 0.5 mmol of 2-[2'-hydroxy-3'-(divinyltriamine) acetyl-5'-methylphenyl] benzotriazole was added, and stirred at 90°C for 18 h, and after cooling, the solution was poured into ethanol, filtered, washed with ethanol, and dried to obtain an amino-terminated polymer ultraviolet absorber.

[0027] (4) 100 g of epoxy resin E51, 1 g of amino-terminated polymer ultraviolet absorber, 0.5 g of defoaming agent ECO-A860, 0.7 g of leveling agent, 1.2 g of dispersant, 11 g of spherical alumina trihydrate, 4 g of cordierite, and 32 g of polyether amine D230 curing agent were added to 130 mL of toluene solvent, and stirred to obtain a spherical alumina-cordierite composite refractory coating composition.

[0028] Example 2:

[0029] (1) To 30 mL of acetonitrile, 22 mmol of 2-(2'-hydroxy-3'-chloroacetyl-5'-methylphenyl) benzotriazole, 20 mmol of 1,7-bis-BOC-1,4,7-triazepane, and 22 mmol of potassium carbonate were added, and stirred at 60°C for 12 h, the solution was distilled under reduced pressure, washed with water, and then purified by recrystallization in ethanol to obtain a benzotriazole precursor.

[0030] (2) To 25 mL of ethyl acetate solution of hydrogen chloride with a concentration of 1 mol / L, 3 g of benzotriazole precursor was added, and the reaction was carried out at room temperature for 5 h. After adding sodium bicarbonate solution, the solution was shaken and then allowed to stand to separate into two layers. The lower aqueous phase was removed, and the upper ethyl acetate extraction phase was dried with anhydrous sodium sulfate. After filtration, the filtrate was distilled under reduced pressure. The product was purified by recrystallization in ethanol to obtain 2-[2'-hydroxy-3'-(divinyltriamine) acetyl-5'-methylphenyl] benzotriazole.

[0031] (3) To 60 mL of dimethyl sulfoxide, 10 mmol of 2-[2'-hydroxy-3'-(divinyltriamine) acetyl-5'-methylphenyl] benzotriazole and 10 mmol of biphenyl dicarboxaldehyde were added. The reaction was carried out in a nitrogen atmosphere, and 1 mmol of 2-[2'-hydroxy-3'-(divinyltriamine) acetyl-5'-methylphenyl] benzotriazole was further added. The reaction was stirred at 110°C for 12 h. After cooling, the solution was poured into ethanol, and then filtered and washed with ethanol. After drying, an amino-terminated polymer ultraviolet absorber was obtained.

[0032] (4) 100 g of epoxy resin E51, 2 g of amino-terminated polymer ultraviolet absorber, 1 g of defoaming agent ECO-A860, 0.4 g of leveling agent, 1.7 g of dispersant, 14 g of spherical aluminum oxide trihydrate, 6 g of cordierite, and 31 g of polyether amine D230 curing agent were added to 130 mL of toluene solvent, and then stirred and mixed to obtain a spherical aluminum oxide-cordierite composite refractory coating composition.

[0033] Example 3:

[0034] (1) To 60 mL of dimethyl sulfoxide, 10 mmol of 2-[2'-hydroxy-3'-(divinyltriamine) acetyl-5'-methylphenyl] benzotriazole (prepared according to the method of Example 1) and 10 mmol of biphenyl dicarboxaldehyde were added. The reaction was carried out in a nitrogen atmosphere, and 0.8 mmol of 2-[2'-hydroxy-3'-(divinyltriamine) acetyl-5'-methylphenyl] benzotriazole was further added. The reaction was stirred at 80°C for 18 h. After cooling, the solution was poured into ethanol, and then filtered and washed with ethanol. After drying, an amino-terminated polymer ultraviolet absorber was obtained.

[0035] (2) 100 g of epoxy resin E51, 3.5 g of amino-terminated polymer ultraviolet absorber, 0.5 g of defoaming agent ECO-A860, 0.8 g of leveling agent, 1.2 g of dispersant, 16 g of spherical aluminum oxide trihydrate, 8 g of cordierite, and 30 g of polyether amine D230 curing agent were added to 130 mL of toluene solvent, and then stirred and mixed to obtain a spherical aluminum oxide-cordierite composite refractory coating composition.

[0036] Example 4:

[0037] (1) To 60 mL of dimethyl sulfoxide, 10 mmol of 2-[2'-hydroxy-3'-(divinyltriamine) acetyl-5'-methylphenyl] benzotriazole (prepared according to the method of Example 1), 10 mmol of diphenyl dicarboxaldehyde were added, the reaction was carried out under a nitrogen atmosphere, and 0.5 mmol of 2-[2'-hydroxy-3'-(divinyltriamine) acetyl-5'-methylphenyl] benzotriazole was added, the reaction was stirred at 110°C for 12 h, and after cooling, the solution was poured into ethanol, filtered, washed with ethanol, and dried to obtain an amino-terminated polymeric ultraviolet absorber.

[0038] (2) 100 g of epoxy resin E51, 5 g of amino-terminated polymeric ultraviolet absorber, 1 g of defoaming agent Ecolink ECO-A860, 0.6 g of leveling agent, 1.2 g of dispersant, 18.5 g of spherical alumina trihydrate, 9.5 g of cordierite, and 29 g of polyetheramine D230 curing agent were added to 130 mL of toluene solvent, stirred and mixed to obtain a spherical alumina-cordierite composite refractory coating composition.

[0039] Comparative Example 1:

[0040] (1) 100 g of epoxy resin E51, 0.5 g of defoaming agent Ecolink ECO-A860, 0.7 g of leveling agent, 1.2 g of dispersant, 11 g of spherical alumina trihydrate, 4 g of cordierite, and 32 g of polyetheramine D230 curing agent were added to 130 mL of toluene solvent, stirred and mixed to obtain a coating composition.

[0041] Comparative Example 2:

[0042] (1) 100 g of epoxy resin E51, 1 g of 2-(2'-hydroxy-3'-chloroacetyl-5'-methylphenyl) benzotriazole, 0.5 g of defoaming agent Ecolink ECO-A860, 0.7 g of leveling agent, 1.2 g of dispersant, 11 g of spherical alumina trihydrate, 4 g of cordierite, and 32 g of polyetheramine D230 curing agent were added to 130 mL of toluene solvent, stirred and mixed to obtain a coating composition.

[0043] Comparative Example 3:

[0044] (1) 100 g of epoxy resin E51, 1 g of benzotriazole precursor, 0.5 g of defoaming agent Ecolink ECO-A860, 0.7 g of leveling agent, 1.2 g of dispersant, 11 g of spherical alumina trihydrate, 4 g of cordierite, and 32 g of polyetheramine D230 curing agent were added to 130 mL of toluene solvent, stirred and mixed to obtain a coating composition.

[0045] Comparative Example 4:

[0046] (1) To 50 mL of dimethyl sulfoxide, add 10 mmol of 2-[2'-hydroxy-3'-(divinyltriamine) acetyl-5'-methylphenyl] benzotriazole (prepared according to the method of Example 1), 10 mmol of glutaraldehyde, and react under a nitrogen atmosphere. Add 0.5 mmol of 2-[2'-hydroxy-3'-(divinyltriamine) acetyl-5'-methylphenyl] benzotriazole, and stir the reaction at 90°C for 18 h. After cooling, pour the solution into ethanol, filter and wash with ethanol, and dry to obtain an amino-terminated polymeric UV absorber.

[0047] (2) Add 100 g of epoxy resin E51, 1 g of amino-terminated polymeric UV absorber, 0.5 g of defoaming agent Ecolink ECO-A860, 0.7 g of leveling agent, 1.2 g of dispersing agent, 11 g of spherical alumina trihydrate, 4 g of cordierite, and 32 g of polyetheramine D230 curing agent to 130 mL of toluene solvent, and stir to obtain a coating composition.

[0048] Coat the coating on the surface of tinplate, and sequentially cure at 80°C for 1 h, at 100°C for 3 h, and at 130°C for 30 min. Test the impact resistance of the paint film according to the GB / T 1732-2020 standard.

[0049] Weigh 10 mg of paint film and place it in a thermal gravimetric analyzer for thermal gravimetric performance analysis under a nitrogen atmosphere, with a temperature rise rate of 10°C / min from room temperature to 700°C.

[0050] Test the water resistance according to the GB / T 1733-1993 standard.

[0051] Place the paint film in a UV aging experiment for UV aging test, with a total power of 240 W and a central wavelength of 365 nm. The test temperature is 55°C, and the UV aging time is 14 days. Observe the surface state of the paint film after UV aging.

[0052] Test the oxygen index and fire retardant performance according to the GB / T 2406.1-2008 standard.

[0053] Table 1

[0054]

[0055]

[0056] T 5％ is the temperature at which 5% of the thermal gravimetric loss occurs. max is the temperature at which the maximum thermal decomposition rate occurs.

[0057] After testing, the epoxy resin coating of Examples 1-4 has higher impact resistance, T 5％ and T maxtemperature, mechanical properties and heat resistance, and excellent water resistance, ultraviolet aging resistance, and weather resistance. This is mainly because the addition of the terminal amino group-containing polymer ultraviolet absorber can replace part of the polyether amine curing agent, and co-cure with the epoxy resin to improve the curing and cross-linking properties of the epoxy resin, avoid the impact of insufficient curing agent on the mechanical properties of the paint film, and provide the paint film with higher impact resistance. Meanwhile, the ultraviolet absorber is a macromolecular polymer, which has higher heat resistance than small molecule ultraviolet absorbers. The molecular backbone of the polymer ultraviolet absorber contains a heat-stable biphenyl structure, which is beneficial to improving the heat resistance and showing higher T 5％ and T max temperature after co-curing with the epoxy resin. Meanwhile, the terminal amino group-containing polymer ultraviolet absorber co-cured with the epoxy resin can tightly cross-link the molecular chain of the epoxy resin and has a hydrophobic biphenyl structure, which can inhibit the entry of water molecules into the paint film and thus improve the water resistance.

[0058] The 2-(2'-hydroxy-3'-chloroacetyl-5'-methylphenyl) benzotriazole added in Comparative Example 2 does not contain an amino group and cannot co-cure with the epoxy resin, which has poor compatibility with the epoxy resin and can affect the impact resistance and mechanical properties of the paint film. Moreover, as a small molecule compound, it has poor heat resistance, resulting in a lower T 5％ and T max temperature of the epoxy resin and poor water resistance.

[0059] The benzotriazole precursor added in Comparative Example 3 contains an amino group and can co-cure with the epoxy resin to maintain good impact resistance and mechanical properties of the epoxy resin. However, the T 5％ and T max temperature of the paint film is low, and the water resistance is poor.

[0060] In Comparative Example 4, the polymer obtained by the polymerization of glutaraldehyde and a benzotriazole precursor does not contain a heat-stable and hydrophobic biphenyl structure, resulting in a lower T 5％ and T max temperature of the paint film and poor water resistance.

[0061] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A process for the preparation of a spherical alumina-cordierite composite refractory coating composition, characterized in that, The preparation method is: Step S1, adding 2-[2'-hydroxy-3'-(divinyltriamine) acetyl-5'-methyl phenyl] benzotriazole, biphenyl dimethyl formaldehyde into dimethyl sulfoxide, reacting in a nitrogen atmosphere, then adding 2-[2'-hydroxy-3'-(divinyltriamine) acetyl-5'-methyl phenyl] benzotriazole, reacting, cooling the solution, pouring into ethanol, filtering, washing, drying to obtain an amino-terminated polymer ultraviolet absorber; Step S2, stirring and uniformly mixing 100 parts by weight of epoxy resin, 1-5 parts by weight of amino-terminated polymer ultraviolet absorber, 0.5-1 part by weight of defoaming agent, 0.4-0.8 part by weight of leveling agent, 1.2-1.7 parts by weight of dispersing agent, 15-28 parts by weight of filler, 29-32 parts by weight of curing agent to obtain a spherical alumina-cordierite composite refractory coating composition; The filler is spherical alumina trihydrate and cordierite; The preparation method of the 2-[2'-hydroxy-3'-(divinyltriamine) acetyl-5'-methyl phenyl] benzotriazole is: Step (1), adding 2-(2'-hydroxy-3'-chloroacetyl-5'-methyl phenyl) benzotriazole, 1,7-bis-BOC-1,4,7-triazepane, potassium carbonate into a solvent, distilling the solution under reduced pressure after reaction, washing, recrystallizing and purifying to obtain a benzotriazole precursor; Step (2), adding the benzotriazole precursor into a hydrogen chloride ethyl acetate solution, reacting at room temperature for 4-5 hours, extracting and separating after reaction, recrystallizing and purifying to obtain 2-[2'-hydroxy-3'-(divinyltriamine) acetyl-5'-methyl phenyl] benzotriazole; The structural formula of the 2-[2'-hydroxy-3'-(divinyltriamine) acetyl-5'-methyl phenyl] benzotriazole is: ； The molar ratio of 2-(2'-hydroxy-3'-chloroacetyl-5'-methyl phenyl) benzotriazole, 1,7-bis-BOC-1,4,7-triazepane, potassium carbonate in step (1) is (1.1-1.3):1:(1.1-1.5).

2. The method of making a spherical alumina-cordierite composite refractory coating composition according to claim 1, characterized in that, The reaction in step S1 is carried out at 80-110°C for 12-18 hours.

3. The method of making a spherical alumina-cordierite composite refractory coating composition according to claim 1, characterized in that, The molar ratio of 2-[2'-hydroxy-3'-(divinyltriamine) acetyl-5'-methyl phenyl] benzotriazole, biphenyl dimethyl formaldehyde in step S1 is (1.05-1.1):

1.

4. The method of making a spherical alumina-cordierite composite refractory coating composition according to claim 1, characterized in that, The solvent in step (1) is any one or combination of acetonitrile, tetrahydrofuran and water.

5. The method of making a spherical alumina-cordierite composite refractory coating composition according to claim 1, characterized in that, The reaction in step (1) is carried out at 35-60°C for 12-24 hours.

6. The method of making a spherical alumina-cordierite composite refractory coating composition according to claim 1, characterized in that, The curing agent in step S2 is a polyether amine curing agent.

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