Preparation method for anti-corrosion modified epoxy resin

Abstract

The present invention relates to the technical field of epoxy resin modification, and in particular to a preparation method for an anti-corrosion modified epoxy resin. According to the present inventi

Description

[0002] The present disclosure belongs to the technical field of epoxy resin modification, and specifically relates to a method for preparing an anti-corrosion modified epoxy resin. BACKGROUND

[0003] Epoxy resin is widely used in the fields of coatings, adhesives, electronic packaging materials, and composites due to low curing shrinkage, desirable adhesion, alkali resistance, anti-corrosion, and water resistance, as well as excellent electrical insulation and mechanical properties. However, due to the high surface energy of hydroxyl groups in an epoxy resin network and a high cross-linking density after curing, the epoxy resin has large internal stress, high brittleness, and poor impact resistance, which limit applications of the epoxy resin in advanced materials together with the disadvantages such as easy degradation at high temperatures and low hydrophobic properties. In recent years, with the rapid development of high-tech industries, there are increasing requirements for the performance of epoxy resins. Therefore, the modification of epoxy resin shows huge research prospects, and modified epoxy resins with excellent comprehensive properties are also more favored by the market.

[0004] Chinese patent publication No. CN113004524A discloses a method for preparing an epoxy-organic silicone resin, which includes subjecting raw materials of a vinyl-containing MT resin and a siloxane ring to equilibrium reaction under the action of an acidic catalyst to obtain a vinyl-containing MDT resin, contacting the vinyl-containing MDT resin with a peroxide and conducting oxidation to obtain an MDT silicone resin containing an epoxy group at the end group. This resin could effectively improve the mechanical properties of the cured epoxy resin while maintaining desirable temperature resistance and weather resistance of the cured epoxy resin. Chinese patent publication No. CN113789143A discloses a room temperature-curable silicone-modified epoxy resin potting glue and a preparation method thereof. The silicone-modified epoxy resin potting glue is prepared by blending an oligomeric siloxane and an organic amine curing agent, and has the advantages of increased flexibility and elongation at break in the glue layer, enhanced anti-aging performance, and desirable moisture-proof effect. However, there are currently few reports on improving the anti-corrosion properties of epoxy resins. SUMMARY

[0005] In view of this, the present disclosure aims to provide a method for preparing an anti-corrosion modified epoxy resin. The anti-corrosion modified epoxy resin according to the present disclosure exhibits excellent heat resistance, anti-corrosion performance, flame retardant performance, and toughness as well as dynamic mechanical properties at high temperature.

[0006] To achieve the above object, the present disclosure provides the following technical solutions:

[0007] The present disclosure provides a method for preparing an anti-corrosion modified epoxy resin, including the following steps:

[0008] mixing an epoxy resin, an organic silane, a soluble epoxy resin solvent, and an organotin catalyst to obtain a mixture, and subjecting the mixture to cross-linking reaction to obtain the anti-corrosion modified epoxy resin.

[0009] In some embodiments, the epoxy resin includes one or more selected from the group consisting of a halogen-free epoxy resin, an E51 epoxy resin, and an E44 epoxy resin.

[0010] In some embodiments, the organic silane includes one or more selected from the group consisting of y-aminopropyltrimethoxysilane, 'y-aminopropyltriethoxysilane, y-(methacryloyloxy)propyltrimethoxysilane, Y-(glycidyloxy)propyltrimethoxysilane, vinyltrimethoxysilane, l,2-bis(tri ethoxy silyl )ethane, tetraethoxy silane, methyltrimethoxysilane, and vinyltri ethoxysilane.

[0011] In some embodiments, the organic silane accounts for 12% to 18% of a mass of the epoxy resin.

[0012] In some embodiments, the organotin catalyst is at least one selected from the group consisting of butylstannoic acid and dibutyltin dilaurate.

[0013] In some embodiments, the organotin catalyst accounts for 0.2% to 0.3% of a mass of the epoxy resin.

[0014] In some embodiments, the soluble epoxy resin solvent is one or more selected from the group consisting of xylene, toluene, and 7V,A-dimethylformamide (DMF).

[0015] In some embodiments, the soluble epoxy resin solvent accounts for 40% to 50% of a mass of the epoxy resin.

[0016] In some embodiments, the cross-linking reaction is conducted at a cross-linking temperature of 147°C to 152°C for 2 h to 5 h.

[0017] In some embodiments, the cross-linking temperature is obtained by heating at a rate of 9°C / min to ll°C / min.

[0018] In some embodiments, the mixing is conducted by: adding the epoxy resin, the organic silane, and the soluble epoxy resin solvent into a reactor, heating to a temperature of 105°C to 115°C, and then adding the organotin catalyst into the reactor.

[0019] The present disclosure further provides an anti-corrosion modified epoxy resin prepared by the method as described in the above solutions, where the anti-corrosion modified epoxy resin has an epoxy equivalent of 190 g / eq to 201 g / eq and a viscosity at 25°C of 4,980 mPa s to 5,023 mPa s.

[0020] The present disclosure provides a method for preparing an anti-corrosion modified epoxy resin, including the following steps: mixing an epoxy resin, an organic silane, a soluble epoxy resin solvent, and an organotin catalyst to obtain a mixture, and subjecting the mixture to cross-linking reaction to obtain the anti-corrosion modified epoxy resin. In the present disclosure, the organic silane is added to modify the epoxy resin. The organic silane is hydrolyzed to produce silanol, which is further hydrolyzed to produce siloxy groups. Silanol molecules could condense and aggregate with each other to form a network-like film, which is resistant to corrosion by external acids, alkalis, and salts. The siloxy groups also are subjected condensation and addition with epoxy groups or hydroxyl groups of the epoxy resin to form a polysiloxane covalent coupling layer, which could enhance the heat resistance, anti-corrosion performance, and flame-retardant effect of a coating formed by the organic silane-modified epoxy resin. Moreover, the addition of silicone segments could also enhance toughness and improve the dynamic mechanical properties at high temperatures, thereby meeting the demands of high-temperature corrosion resistance for equipment in petroleum and chemical industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG. 1 shows infrared spectra of silicone, anti-corrosion modified resins at heat preservation stages (for 30 min, 150 min, and 270 min) during the reaction and after washing with n-butane in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The present disclosure provides a method for preparing an anti-corrosion modified epoxy resin, including the following steps:

[0023] mixing an epoxy resin, an organic silane, a soluble epoxy resin solvent, and an organotin catalyst to obtain a mixture, and subjecting the mixture to cross-linking reaction to obtain the anti-corrosion modified epoxy resin.

[0024] In the present disclosure, unless otherwise specified, there is no special limitation on sources of the raw materials used herein, and commercially-available products well known to those skilled in the art may be used.

[0025] In the present disclosure, an epoxy resin, an organic silane, a soluble epoxy resin solvent, and an organotin catalyst are mixed to obtain a mixture.

[0026] In some embodiments, the epoxy resin includes one or more selected from the group consisting of a halogen-free epoxy resin, an E51 epoxy resin, and an E44 epoxy resin. In further embodiments, the epoxy resin is the halogen-free epoxy resin or E51 epoxy resin. Under the condition that a plurality of epoxy resins are used, there is no special limitation on a ratio of the different types of epoxy resins, and any ratio may be used. In some embodiments, the epoxy resin is an epoxy resin polymer, the halogen-free epoxy resin comes from Jiangsu Yangnong Kumho Chemical Co., Ltd., with a model of YN3573K70.

[0027] In some embodiments, the organic silane includes one or more selected from the group consisting of y-aminopropyltrimethoxy silane, yami nopropyl tri ethoxy silane, ' / -(methacryloyloxy )propyltrimethoxysilane, y-(glycidyloxy)propyltrimethoxysilane, vinyltrimethoxysilane, l,2-bis(triethoxysilyl)ethane, tetraethoxysilane, methyltrimethoxysilane, and vinyltriethoxysilane. In further embodiments, the organic silane is the tetraethoxysilane or methyltrimethoxysilane. Under the condition that a plurality of organic silanes are used, there is no special limitation on a ratio of the different types of organic silanes, and any ratio may be used. In some embodiments, the organic silane accounts for 12% to 18%, preferably 13% to 15% of a mass of the epoxy resin.

[0028] In some embodiments, the organotin catalyst is at least one of butylstannoic acid and dibutyltin dilaurate. In further embodiments, the organotin catalyst is the butylstannoic acid. Under the conditions that the two organotin catalysts are used, there is no special limitation on a ratio of the two types of organotin catalysts, and any ratio may be used. In some embodiments, the organotin catalyst accounts for 0.2% to 0.3%, preferably 0.22% to 0.25% of a mass of the epoxy resin.

[0029] In some embodiments, the soluble epoxy resin solvent is one or more selected from the group consisting of xylene, toluene, and DMF In further embodiments, the soluble epoxy resin solvent is xylene or toluene. Under the condition that a plurality of soluble epoxy resin solvents would be used, there is no special restriction on a ratio of the different types of soluble epoxy resin solvents, and any ratio may be used. In some embodiments, the soluble epoxy resin solvent accounts for 40% to 50%, preferably 42% to 45% of a mass of the epoxy resin.

[0030] In some embodiments, the mixing is conducted by: adding the epoxy resin, the organic silane, and the soluble epoxy resin solvent into a reactor, heating to a temperature of 105°C to 115°C, preferably 110°C, and then adding the organotin catalyst into the reactor to obtain a mixture.

[0031] In some embodiments, the mixture of the epoxy resin, organic silane, and soluble epoxy resin solvent is heated to achieve reaction activation energy so as to promote the reaction.

[0032] In the present disclosure, the mixture is subjected to cross-linking reaction to obtain the anti-corrosion modified epoxy resin.

[0033] In some embodiments, the cross-linking reaction is conducted at a cross-linking temperature of 147°C to 152°C, preferably 150°C. In some embodiments, the cross-linking reaction is conducted for 2 h to 5 h, preferably 2.5 h to 4.5 h. In some embodiments, the cross-linking temperature is obtained by heating at a rate of 9°C / min to 1 l°C / min, preferably 10°C / min.

[0034] During the cross-linking reaction, the organic silane is subjected to self-polycondensation after hydrolysis, and then subjected to condensation and addition with an epoxy group or a hydroxyl group of the epoxy resin, respectively, thus forming a polysiloxane covalent coupling layer, which could enhance heat resistance and anti-corrosion properties of a coating formed by the organic silane-modified epoxy resin.

[0035] In the present disclosure, the anti-corrosion modified epoxy resin prepared in Example 1 has a structural formula as follows: R~ -C(CH3)r

[0036] It can be seen that the alkoxy groups of the organic silane and the hydroxyl groups of the epoxy resin are subjected to cross-linking reaction to form a copolymer. A stable Si-0 bond is introduced into the epoxy structure to obtain the anti-corrosion modified epoxy resin. The synergy of P and Si in an epoxy resin structure could achieve a flame-retardant effect, and the addition of silicone segments could also enhance toughness and improve the dynamic mechanical properties at high temperatures. Accordingly, a resulting coating shows excellent heat resistance, flame retardancy, and anti-corrosion properties, could meet the demands of high-temperature corrosion resistance for equipment in petroleum and chemical industries, and is easy to construct and save cost.

[0037] The technical solutions of the present disclosure will be described below clearly and completely in conjunction with the examples of the present disclosure, but these examples shall not be construed as limiting the scope of the present disclosure.

[0038] Example 1

[0039] 330 g of a halogen-free epoxy resin and 46.3 g of methyltrimethoxysilane were added into a four-neck flask, 145 g of xylene was then added thereto. A resulting reaction system was heated to 110°C, 0.76 g of butylstannoic acid was then added thereto, and a resulting mixture was heated to 150°C at a rate of 10°C / min and then held at this temperature for 4.5 h to obtain an anti-corrosion modified epoxy resin.

[0040] Example!

[0041] 330 g of a halogen-free epoxy resin and 46.3 g of tetraethoxy si lane were added into a four-neck flask, 165 g of toluene was then added thereto. A resulting reaction system was heated to 110°C, 0.76 g of butylstannoic acid was then added thereto, and a resulting mixture was heated to 150°C at a rate of 10°C / min and then held at this temperature for 2.5 h to obtain an anti-corrosion modified epoxy resin.

[0042] Examples

[0043] 330 g of a halogen-free epoxy resin and 59.4 g of methyltrimethoxysilane were added into a four-neck flask, 145 g of xylene was then added thereto. A resulting reaction system was heated to 110°C, 1 g of butylstannoic acid was then added thereto, and a resulting mixture was heated to 150°C at a rate of 10°C / min and then held at this temperature for 2.5 h to obtain an anti-corrosion modified epoxy resin.

[0044] Example 4

[0045] 330 g of a halogen-free epoxy resin and 39.6 g of methyltrimethoxysilane were added into a four-neck flask, 145 g of xylene was then added thereto. A resulting reaction system was heated to 110°C, 0.76 g of butylstannoic acid was then added thereto, and a resulting mixture was heated to 150°C at a rate of 10°C / min and then held at this temperature for 2.5 h to obtain an anti-corrosion modified epoxy resin.

[0046] Example 5

[0047] 330 g of a halogen-free epoxy resin and 49.5 g of tetraethoxy si lane were added into a four-neck flask, 162 g of toluene was then added thereto. A resulting reaction system was heated to 110°C, 0.76 g of butylstannoic acid was then added thereto, and a resulting mixture was heated to 150°C at a rate of 10°C / min and then held at this temperature for 2.5 h to obtain an anti-corrosion modified epoxy resin.

[0048] Comparative Example 1

[0049] The halogen-free epoxy resin was used as a comparative example.

[0050] Performance testing

[0051] The anti-corrosion modified epoxy resins prepared in Examples 1 to 5 and the halogen-free epoxy resin were separately mixed with a polyamide curing agent (KCA2300) at a mass ratio of 5:1. A resulting mixture was coated onto a pretreated carbon steel with a coating rod at a thickness of 70 pm to 90 pm, and a resulting coated carbon steel was cured at 70°C for 2 h to obtain a coating. The performances of the anti-corrosion modified epoxy resins prepared in Examples 1 to 5 and the halogen-free epoxy resin in Comparative Example 1 as well as the corresponding coatings were measured. The results are shown in Tables 1 and 2.

[0052] Table 1 Performance test results of anti-corrosion modified epoxy resins prepared in Examples 1 to 5 and halogen-free epoxy resin in Comparative Example 1

[0053] Example No. Epoxy equivalent (g / eq) Viscosity (mPa s / 25°C) Example 1 190 5000 Example 2 192 4980 Example 3 201 5016 Example 4 196 5015 Example 5 195 5023 Comparative Example 1 185 5320

[0054] Table 2 Test results of coatings obtained from anti-corrosion modified epoxy resins prepared in Examples 1 to 5 and halogen-free epoxy resin in Comparative Example 1

[0055] Examples Coating appearance Pencil hardness (H) Impact resistance (kg / cm) Heat resistance (appearance after 100 hat 600°C) Acid resistance (8 h in 3% acetic acid aqueous solution at 60°C) Salt tolerance (36 h in 5% NaCl aqueous solution at 60°C) 1 The coating 3 50 The coating The coating The coating is light yellow, smooth, and matte is complete and even, with slight loss of gloss does not discolor, blister, or peel off does not discolor, blister, or peel off 2 3 50 The coating is complete and even, with slight loss of gloss The coating discolors slightly, and does not blister or peel off The coating discolors slightly, does not blister or peel off 3 3 50 The coating is complete and even, with slight loss of gloss The coating discolors slightly, does not blister or peel off The coating discolors slightly, does not blister or peel off 4 3 50 The coating is complete and even, with slight loss of gloss The coating discolors slightly, does not blister or peel off The coating discolors slightly, does not blister or peel off 5 3 50 The coating is complete and even, with slight loss of gloss The coating discolors slightly, does not blister or peel off The coating discolors slightly, does not blister or peel off Halogen-free epoxy resin The coating is transparent and smooth 3 50 The coating turns to be black The coating discolors, blisters, and partially peels off The coating discolors, blisters, and partially peels off Test method Visual inspection GB / T 6739-2006 GB / T 1732-1993 GB / T 1735-2009 Visual inspection Visual inspection

[0056] As shown in Table 1, the anti-corrosion modified epoxy resin according to the present disclosure has an epoxy equivalent of 190 g / eq to 201 g / eq, which is higher than 185 g / eq of the halogen-free epoxy resin in Comparative Example 1; and the anti-corrosion modified epoxy resin has a viscosity of 4,980 mPa s / 25°C to 5,023 mPa s / 25°C, which is lower than 5,320 mPa s / 25°C of the halogen-free epoxy resin in Comparative Example 1.

[0057] As shown in Table 2, the coating formed by the anti-corrosion modified epoxy resin according to the present disclosure shows better heat resistance, acid resistance, and salt resistance than those of the coating obtained by the halogen-free epoxy resin in Comparative Example 1.

[0058] (2) The infrared testing was conducted separately on the silicone, anti-corrosion modified resins at heat preservation stages (30 min, 150 min, and 270 min) during the reaction and after washing with n-butane in Example 1. The results are shown in FIG. 1.

[0059] As shown in FIG. 1, according to the disclosure of existing literatures, it can be found that the characteristic peak at 2,840 cm'1 attributes to the methoxy group, and silicone does have a moderately strong absorption peak at this position. As the reaction progresses, this peak has a continuously decreased intensity, but still exists after heat preservation for 270 min, indicating that the silicone participates in the reaction but does not react completely. In fact, n-hexane was added to precipitate and wash the modified resin, and a washing liquid was filtered for infrared testing. The results shows that there is still an obvious absorption peak at 2,840 cm'1, proving that the silicone is not completely reacted.

[0060] Although the above examples have described the present disclosure in detail, they are only a part of, not all of, the embodiments of the present disclosure. Other embodiments could be obtained by persons based on the examples without creative efforts, and all of these embodiments shall fall within the scope of the present disclosure.

Claims

1. A method for preparing an anti-corrosion modified epoxy resin, comprising the following steps:mixing an epoxy resin, an organic silane, a soluble epoxy resin solvent, and an organotin catalyst to obtain a mixture, and subjecting the mixture to cross-linking reaction to obtain the anti-corrosion modified epoxy resin.

2. The method according to claim 1, wherein the epoxy resin comprises one or more selected from the group consisting of a halogen-free epoxy resin, an E51 epoxy resin, and an E44 epoxy resin.

3. The method according to claim 1, wherein the organic silane comprises one or more selected from the group consisting of y-aminopropyltrimethoxysilane, y-aminopropyltriethoxysilane, ' / -(methacryloyl oxy )propyltrimethoxysilane, y-(glycidyloxy)propyltrimethoxysilane,vinyltrimethoxysilane, l,2-bis(triethoxysilyl)ethane, tetraethoxy silane, methyltrimethoxysilane, and vinyltri ethoxysilane.

4. The method according to claim 1, 2, or 3, wherein the organic silane accounts for 12% to 18% of a mass of the epoxy resin.

5. The method according to claim 1, wherein the organotin catalyst is at least one selected from the group consisting of butyl stannoic acid and dibutyltin dilaurate.

6. The method according to claim 1, 2, or 5, wherein the organotin catalyst accounts for 0.2% to 0.3% of a mass of the epoxy resin.

7. The method according to claim 1, wherein the soluble epoxy resin solvent is one or more selected from the group consisting of xylene, toluene, and 7V,7V-dimethylformamide (DMF).

8. The method according to claim 1, 2, or 7, wherein the soluble epoxy resin solvent accounts for 40% to 50% of a mass of the epoxy resin.

9. The method according to claim 1, wherein the cross-linking reaction is conducted at a cross-linking temperature of 147°C to 152°C for 2 h to 5 h.

10. The method according to claim 9, wherein the cross-linking temperature is obtained by heating at a rate of 9°C / min to ll°C / min.

11. The method according to claim 1, wherein the mixing is conducted by adding the epoxy resin, the organic silane, and the soluble epoxy resin solvent into a reactor, heating to a temperature of 105°C to 115°C, and then adding the organotin catalyst into the reactor.

12. An anti-corrosion modified epoxy resin prepared by the method according to any one of claims 1 to 11, wherein the anti-corrosion modified epoxy resin has an epoxy equivalent of 190 g / eq to 201 g / eq and a viscosity at 25°C of 4,980 mPa s to 5,023 mPa s.

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