Water-borne epoxy resin, coating and preparation method and application of water-borne epoxy resin and coating

Abstract

The invention discloses waterborne epoxy resin, a coating and a preparation method and application thereof, and relates to the technical field of high polymer materials. The water-borne epoxy resin has a specific structure, the structure contains units of glycidol, bisphenol A and fluorophthalic anhydride, the water-borne epoxy resin does not contain chloride ions and can be used for preparing low-chlorine, low-sulfur and low-lead water-borne epoxy coatings, the corrosion resistance of coatings formed by the water-borne epoxy coatings is improved, the service life of the coatings formed by the water-borne epoxy coatings is prolonged, and the service life of the coatings is prolonged. The obtained coating is improved in acid and alkali resistance, water resistance and salt spray resistance, has good adhesive force, is suitable for preparing the coating for stainless steel, and can effectively prevent free chloride ions from damaging a stainless steel passive film protective layer.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to an aqueous epoxy resin, a coating, and a preparation method and application thereof. Background Art

[0002] At present, the scale of coatings in the petrochemical market is relatively large. However, for petrochemical stainless steel equipment and other fields, such as the anti-corrosion coating on the surface of stainless steel fire truck tanks, due to special requirements, such as strict restrictions on the content of chlorine, sulfur, lead, etc. in the coating, there are few coatings suitable for petrochemical stainless steel equipment. Stainless steel itself has excellent corrosion resistance, while free chloride ions can damage the passivation film protective layer of stainless steel, resulting in corrosion. The traditional raw materials for synthesizing epoxy resin are generally epichlorohydrin, and chloride ions will be generated during the synthesis process. Even if strict separation and purification are carried out, it is difficult to remove all chloride ions, and the chloride ion content requirements for coatings used on stainless steel cannot be met. Summary of the Invention

[0003] The present invention aims to at least solve the above technical problems existing in the prior art. For this reason, the object of the present invention is to provide an aqueous epoxy resin that does not contain chloride ions, sulfur, or lead and can meet the requirements for coatings with strict content requirements for chlorine, sulfur, lead, etc.

[0004] The second aspect of the present invention lies in providing a preparation method for the aqueous epoxy resin.

[0005] The third aspect of the present invention lies in providing a coating.

[0006] The fourth aspect of the present invention lies in providing a preparation method for the coating.

[0007] The fifth aspect of the present invention lies in providing a coating for stainless steel.

[0008] In order to achieve the above object, the technical solutions adopted by the present invention are as follows:

[0009] The first aspect of the present invention provides an aqueous epoxy resin having the structure shown in the following formula (1):

[0010]

[0011] Wherein, R1 to R4 are independently hydrogen or fluorine, and at least one of R1 to R4 is fluorine; n is an integer from 1 to 8.

[0012] The present invention provides an aqueous epoxy resin having the structure of formula (1). This aqueous epoxy resin does not contain chloride ions. When used to prepare an aqueous epoxy coating, it can reduce the chloride ion content at the raw material level and effectively weaken the negative impact of free chloride ions on the anti-corrosion performance of the coating.

[0013] In some embodiments of the present invention, n is an integer from 1 to 5.

[0014] In some embodiments of the present invention, the raw materials for preparing the waterborne epoxy resin include epoxy resin and fluorophthalic anhydride; the raw materials for preparing the epoxy resin include epichlorohydrin and bisphenol A.

[0015] The present invention uses epichlorohydrin and bisphenol A to prepare epoxy resin, avoiding the introduction of chlorine-containing raw materials (such as epichlorohydrin), and the resulting waterborne epoxy resin does not contain chloride ions. Further, fluorophthalic anhydride is used to hydrophilize the epoxy resin, grafting carboxyl groups in the epoxy resin structure to neutralize and form salts, thereby obtaining a waterborne epoxy resin. At the same time, the C-F bond in fluorophthalic anhydride has a relatively large bond energy and strong stability, and will not react with various strong oxidants, strong acids, strong alkalis, etc. to decompose, and is stable in electrolytes, which helps to improve the anti-corrosion performance and stability of the coating formed by the coating, and the service life is extended.

[0016] In some embodiments of the present invention, the epoxy equivalent of the waterborne epoxy resin is 400 - 1000 g / mol.

[0017] In some embodiments of the present invention, the epoxy equivalent of the waterborne epoxy resin is 420 - 900 g / mol.

[0018] In some specific embodiments of the present invention, the epoxy equivalent of the waterborne epoxy resin is 450 - 600 g / mol.

[0019] In some embodiments of the present invention, the molar ratio of the epoxy resin to the fluorophthalic anhydride is 1:(1 - 4).

[0020] In some embodiments of the present invention, the molar ratio of the epoxy resin to the fluorophthalic anhydride is 1:(1 - 2).

[0021] Specifically, the molar ratio of the epoxy resin to the fluorophthalic anhydride can be 1:1, 1:1.2, 1:1.5, 1:2, 1:3, or 1:4.

[0022] In some embodiments of the present invention, the fluorophthalic anhydride includes at least one of tetrafluorophthalic anhydride and 3-fluorophthalic anhydride.

[0023] In some embodiments of the present invention, the molar ratio of the epichlorohydrin to the bisphenol A is 1:(1 - 5).

[0024] In some embodiments of the present invention, the molar ratio of the epichlorohydrin to the bisphenol A is 1:(1 - 3).

[0025] The second aspect of the present invention provides a method for preparing the aqueous epoxy resin described in the first aspect of the present invention, comprising the following steps:

[0026] React glycidol and bisphenol A under the action of a catalyst to obtain an epoxy resin; react the epoxy resin with fluorophthalic anhydride to obtain the aqueous epoxy resin.

[0027] In some embodiments of the present invention, the catalyst for glycidol and bisphenol A includes DEAD (diethyl azodicarboxylate); the mass fraction of DEAD is 0.2-1%.

[0028] In some embodiments of the present invention, the reaction of the epoxy resin with fluorophthalic anhydride is carried out under the catalysis of DBTDL (dibutyltin dilaurate); the mass fraction of DBTDL is 0.1-0.5%.

[0029] In some embodiments of the present invention, the reaction temperature of glycidol and bisphenol A is 120-140°C; the reaction temperature of the epoxy resin with fluorophthalic anhydride is 120-140°C.

[0030] The third aspect of the present invention provides a coating, comprising the aqueous epoxy resin described in the first aspect of the present invention.

[0031] The aqueous epoxy resin of the present invention does not contain chloride ions, and can be used to prepare a low-chlorine, low-sulfur, and low-lead aqueous epoxy coating, improving the anti-corrosion performance and service life of the coating formed by the aqueous epoxy coating. The obtained coating has improved acid and alkali resistance, water resistance, and salt spray resistance, and has good adhesion.

[0032] In some embodiments of the present invention, the aqueous epoxy resin comprises component A and component B;

[0033] Component A, by mass, comprises the following components:

[0034] 20-35 parts of aqueous epoxy resin, 30-50 parts of filler, 6.9-24.1 parts of auxiliary agent, 20-35 parts of water;

[0035] Component B, by mass, comprises the following components:

[0036] 2-50 parts of aqueous epoxy curing agent, 4.5-21 parts of auxiliary agent, 35-60 parts of water.

[0037] In some embodiments of the present invention, the aqueous epoxy resin comprises component A and component B;

[0038] Component A, by mass, comprises the following components:

[0039] 20 - 30 parts of water - borne epoxy resin, 35 - 45 parts of filler, 9.05 - 18.5 parts of additives, 20 - 30 parts of water;

[0040] Component B, by mass parts, includes the following components:

[0041] 25 - 40 parts of water - borne epoxy curing agent, 9.8 - 17 parts of additives, 45 - 55 parts of water.

[0042] In some embodiments of the present invention, the additives of Component A, by mass parts, include the following components: 0.1 - 0.5 part of neutralizing agent, 0.2 - 0.6 part of dispersant, 0.1 - 0.5 part of defoaming agent, 2 - 10 parts of coloring pigment, 4 - 10 parts of rust - inhibiting pigment, 0 - 0.5 part of wetting agent, 0.5 - 2 parts of thickening agent.

[0043] In some embodiments of the present invention, the additives of Component A, by mass parts, include the following components: 0.1 - 0.4 part of neutralizing agent, 0.3 - 0.6 part of dispersant, 0.1 - 0.3 part of defoaming agent, 4 - 8 parts of coloring pigment, 4 - 7 parts of rust - inhibiting pigment, 0.05 - 0.2 part of wetting agent, 0.5 - 2 parts of thickening agent.

[0044] In some embodiments of the present invention, the additives of Component B, by mass parts, include the following components: 0.5 - 1 part of anti - flash rust agent, 3 - 15 parts of film - forming aid, 1 - 5 parts of defoaming agent.

[0045] In some embodiments of the present invention, the additives of Component B, by mass parts, include the following components: 0.8 - 1 part of anti - flash rust agent, 8 - 12 parts of film - forming aid, 1 - 4 parts of defoaming agent.

[0046] In some embodiments of the present invention, the water - borne epoxy resin includes Component A and Component B;

[0047] Component A, by mass parts, includes the following components:

[0048] 20 - 35 parts of water - borne epoxy resin, 30 - 50 parts of filler, 0.1 - 0.5 part of neutralizing agent, 0.2 - 0.6 part of dispersant, 0.1 - 0.5 part of defoaming agent, 2 - 10 parts of coloring pigment, 4 - 10 parts of rust - inhibiting pigment, 0 - 0.5 part of wetting agent, 0.5 - 2 parts of thickening agent, 20 - 35 parts of water;

[0049] Component B, by mass parts, includes the following components:

[0050] 2 - 50 parts of water - borne epoxy curing agent, 0.5 - 1 part of anti - flash rust agent, 3 - 15 parts of film - forming aid, 1 - 5 parts of defoaming agent, 35 - 60 parts of water.

[0051] In some embodiments of the present invention, in Component A: the neutralizing agent includes at least one of triethanolamine, triethylamine, and tributylamine; the dispersant includes at least one of anionic carboxylate dispersants, cationic quaternary ammonium salt dispersants, and non-ionic high molecular weight polymer dispersants; the defoaming agent includes at least one of silicone defoaming agents and mineral oil defoaming agents; the coloring pigment includes at least one of iron oxide black, iron oxide red, carbon black, and titanium dioxide; the filler includes at least one of talc powder, mica powder, calcined kaolin, and silica powder; the rust-inhibiting pigment includes at least one of silica, zinc molybdate, and strontium chromate; the wetting agent includes modified polysiloxane wetting agents; the thickening agent includes at least one of polyurethane thickeners and alkali-swellable thickeners.

[0052] In some embodiments of the present invention, in Component B: the waterborne epoxy curing agent includes modified amine curing agents; the anti-flash rust agent includes at least one of waterborne organic anti-flash rust agents and waterborne inorganic anti-flash rust agents; the film-forming aid includes at least one of lauryl alcohol esters, propylene glycol, dipropylene glycol butyl ether, diethylene glycol butyl ether, and propylene glycol diacetate; the defoaming agent includes at least one of mineral oil defoaming agents and silicone defoaming agents.

[0053] In some embodiments of the present invention, the mass ratio of Component A to Component B is (3 - 8):1.

[0054] In some embodiments of the present invention, the mass ratio of Component A to Component B is (5 - 8):1.

[0055] The fourth aspect of the present invention provides a method for preparing the coating described in the third aspect of the present invention, including the following steps:

[0056] Mix each component in Component A and Component B respectively to obtain the coating.

[0057] During use, mix Component A and Component B, and then the coating can be applied.

[0058] The fifth aspect of the present invention provides a coating for stainless steel, and the preparation raw materials include the coating described in the third aspect of the present invention.

[0059] In some embodiments of the present invention, the coating is an anti-corrosion coating.

[0060] In some embodiments of the present invention, the stainless steel includes petrochemical stainless steel equipment or stainless steel fire truck tanks.

[0061] Compared with the prior art, the beneficial effects of the present invention are:

[0062] (1) The waterborne epoxy resin of the present invention has a specific structure as shown in formula (1), does not contain chloride ions, and has a fluorine-containing chain segment in its structure, which has good compatibility with the waterborne system and can exert its own advantages. During the preparation process of this waterborne epoxy resin, epichlorohydrin is not required, thus eliminating the introduction of chloride ions, and it is suitable for the preparation of coatings with low chlorine, low sulfur, and low lead content.

[0063] (2) The waterborne epoxy resin of the present invention does not contain chloride ions. When used to prepare coatings, it can improve the anti-corrosion performance and service life of the coatings formed by waterborne epoxy coatings. The obtained coatings have improved acid and alkali resistance, water resistance, and salt spray resistance, and have good adhesion. At the same time, they have the characteristics of environmental protection, safety, and easy construction, and are suitable for the preparation of coatings for stainless steel, which can effectively avoid the damage of free chloride ions to the passivation film protection layer of stainless steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 1H NMR spectrum of the waterborne epoxy resin obtained in Preparation Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0065] The content of the present invention will be further described in detail through specific examples below. Unless otherwise specified, the raw materials, reagents, or devices used in the examples and comparative examples can be obtained from conventional commercial channels or can be obtained by existing technical methods. Unless otherwise specified, the test or measurement methods are all conventional methods in the art.

[0066] The raw materials in the following examples and comparative examples of the present invention are described as follows:

[0067] Neutralizing agent: Commercially available triethanolamine;

[0068] Dispersant: BYK-190;

[0069] Defoaming agent 1: Matsuo 8807;

[0070] Defoaming agent 2: Air Products MD-20;

[0071] Coloring pigment: Commercially available iron oxide red;

[0072] Filler: A mixture of commercially available mica powder and silica powder, with a mass ratio of 1:1;

[0073] Rust-inhibiting pigment: Commercially available zinc molybdate;

[0074] Wetting agent: BYK-346;

[0075] Thickening agent: BYK-420;

[0076] Waterborne epoxy curing agent: L-920-50H from Dongguan Sanqi Chemical Raw Materials Co., Ltd.;

[0077] Flash rust inhibitor: commercially available sodium nitrite;

[0078] Film-forming aid: a mixture of dipropylene glycol monobutyl ether and diethylene glycol monobutyl ether in a mass ratio of 1:1.

[0079] The following is a detailed description in combination with specific preparation examples, examples and comparative examples.

[0080] Preparation Example 1

[0081] This preparation example provides an aqueous epoxy resin with the structural formula shown in the following formula (2):

[0082] where n is 1.

[0083] The preparation process of the aqueous epoxy resin is as follows:

[0084]

[0085] The specific preparation method is as follows: React glycidol and bisphenol A in a molar ratio of 1:1 under the catalysis of 0.2% (mass fraction) DEAD (diethyl azodicarboxylate) to obtain an epoxy resin, and the reaction temperature is 130 °C; Mix the epoxy resin and tetrafluorophthalic anhydride in a molar ratio of 1:1 and react under the catalysis of 0.2% (mass fraction) DBTDL (dibutyltin dilaurate) to obtain an aqueous epoxy resin, and the reaction temperature is 130 °C; The fineness of the obtained aqueous epoxy resin slurry does not exceed 50 μm, and the epoxy equivalent of the aqueous epoxy resin is 450 g / mol.

[0086] The nuclear magnetic resonance hydrogen spectrum of the aqueous epoxy resin in Preparation Example 1 is as Figure 1 shown. It can be seen that the methine peak at 4.6 disappears, indicating that the side-chain hydroxyl group reacts with tetrafluorophthalic anhydride.

[0087] Preparation Example 2

[0088] This preparation example provides an aqueous epoxy resin, which is different from Preparation Example 1 in that n in formula (2) is 2, and the molar ratio of glycidol and bisphenol A in the preparation process is 1:1.5; The epoxy equivalent of the aqueous epoxy resin is 600 g / mol; The rest is the same as Preparation Example 1.

[0089] Preparation Example 3

[0090] This preparation example provides an aqueous epoxy resin, which is different from Preparation Example 1 in that n in formula (2) is 4, and the molar ratio of glycidol and bisphenol A in the preparation process is 1:2.5; The epoxy equivalent of the aqueous epoxy resin is 900 g / mol; The rest is the same as Preparation Example 1.

[0091] Preparation Example 4

[0092] This Preparation Example provides a waterborne epoxy resin, which is different from Preparation Example 1 in that 3-fluorophthalic anhydride is used instead of tetrafluorophthalic anhydride during the preparation process. The obtained waterborne epoxy resin has the structure shown in Formula (1), where R1 is fluorine, R3 to R4 are hydrogen, and n is 1; the epoxy equivalent of the waterborne epoxy resin is 420 g / mol; the rest is the same as Preparation Example 1.

[0093] Examples 1 to 3

[0094] Examples 1 to 3 provide a coating. For the formulation, refer to Table 1 and Table 2. The waterborne epoxy resins used are the waterborne epoxy resins of Preparation Example 1, Preparation Example 2, and Preparation Example 4 in sequence. The specific corresponding relationship is shown in Table 3.

[0095] Table 1 Coating Formulation Table for Examples 1 to 3

[0096]

[0097] Table 2 Proportion Table of Component A and Component B in the Coatings of Examples 1 to 3

[0098] Component A: Component B (mass ratio) Example 1 6:1 Example 2 7:1 Example 3 6:1

[0099] Table 3 Waterborne Epoxy Resin Table for Examples 1 to 3

[0100]

[0101]

[0102] The preparation method of the coatings in Examples 1 to 3 is as follows:

[0103] According to the mass ratio, under stirring conditions, add the waterborne epoxy resin and the neutralizing agent to deionized water, then add the dispersant and the defoaming agent. After dispersing evenly, add the coloring pigment, the filler, and the rust-inhibiting pigment, and grind evenly to obtain a slurry; add the wetting agent and the thickener to the slurry, and after dispersing evenly, obtain Component A;

[0104] Add the waterborne epoxy curing agent, the anti-flash rust agent, the film-forming aid, the thickener, the defoaming agent, and deionized water according to the mass ratio, and disperse evenly to obtain Component B;

[0105] When in use, mix Component A and Component B.

[0106] Example 4

[0107] This example provides a coating, which is different from Example 1 in that the dosage of each component is as shown in Table 4 below; the rest is the same as Example 1.

[0108] Table 4 Coating Formulation Table for Example 4

[0109]

[0110] Example 5

[0111] This example provides a coating, which is different from Example 4 in that the waterborne epoxy resin of Preparation Example 3 is used, and the mass ratio of Component A to Component B is 8:1; the rest are the same as in Example 4.

[0112] Comparative Example 1

[0113] Comparative Example 1 provides a coating, which is different from Example 1 in that an equal amount of Hexion 6520 epoxy emulsion is used to replace the waterborne epoxy resin of Preparation Example 1; the rest are the same as in Example 1.

[0114] Comparative Example 2

[0115] Comparative Example 1 provides a coating, which is different from Example 1 in that an equal amount of Kast W305A waterborne epoxy resin (solid content 90%) is used to replace the waterborne epoxy resin of Preparation Example 1; the rest are the same as in Example 1.

[0116] Comparative Example 3

[0117] Comparative Example 1 provides a coating, which is different from Example 1 in that an equal amount of Nanya 128 bisphenol A epoxy resin is used to replace the waterborne epoxy resin of Preparation Example 1; the rest are the same as in Example 1.

[0118] Result Detection

[0119] The coatings obtained from the above examples and comparative examples were applied to stainless steel, with a film thickness of 250 - 300 μm, and air-dried at room temperature for 14 days for curing.

[0120] Refer to GB / T 50393 - 2017 to test the acid and alkali resistance, water resistance, and salt spray resistance of the paint film; refer to HG / T 5178 - 2017 to test the adhesion of the paint film (pull-off method).

[0121] The chloride ion, sulfur, and lead contents were obtained by ion chromatography testing.

[0122] The test results are shown in Table 5.

[0123] Table 5 Test Results of Coating Properties of Examples and Comparative Examples

[0124]

[0125]

[0126] It can be seen from the test results in Table 5 that for Examples 1 to 5 using the waterborne epoxy resin of the present invention, the coatings obtained meet the standard requirements in terms of chloride ion content and lead sulfate content. Moreover, the chloride ion content is one order of magnitude lower than that of Comparative Examples 1 to 3, not exceeding 5.2 mg / kg, effectively avoiding the negative impact of free chloride ions on the anti-corrosion performance of stainless steel, and improving the acid and alkali resistance, water resistance and salt spray resistance. In addition, the coating has good adhesion.

[0127] Combining Example 1 and Comparative Examples 1 to 3, it can be seen that since the waterborne epoxy resin of the present invention does not require the raw material epichlorohydrin, the chloride ion content is greatly reduced. At the same time, a fluorine-containing segment is introduced into the waterborne epoxy resin of the present invention, which significantly improves the anti-corrosion performance of the coating. The resin in Comparative Example 3 was not waterborne, and its performance could not be reflected in the waterborne system. However, the waterborne epoxy resin of the present invention was modified with anhydride and neutralized to form a salt, having good compatibility with the waterborne system and excellent performance.

[0128] In summary, the waterborne epoxy resin of the present invention does not contain chloride ions, can be used to prepare waterborne epoxy coatings with low chlorine, low sulfur and low lead, improve the anti-corrosion performance and service life of the coatings formed by the waterborne epoxy coatings. The obtained coatings have improved acid and alkali resistance, water resistance and salt spray resistance, and have good adhesion, are suitable for preparing coatings for stainless steel, and can effectively avoid the damage of free chloride ions to the passivation film protection layer of stainless steel.

[0129] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A water-based epoxy resin, characterized in that The waterborne epoxy resin has a structure as shown in the following formula (1): Wherein, R1-R4 are independently hydrogen or fluorine, and at least one of R1-R4 is fluorine; and n is an integer of 1-8.

2. The waterborne epoxy resin according to claim 1, characterized in that The raw materials for preparing the waterborne epoxy resin include epoxy resin and fluorophthalic anhydride; the raw materials for preparing the epoxy resin include glycidol and bisphenol A; And / or, the epoxy equivalent of the waterborne epoxy resin is 400 to 1000 g / mol.

3. The waterborne epoxy resin according to claim 2, characterized in that: The molar ratio of the epoxy resin to fluorophthalic anhydride is 1:(1-4); And / or, the fluorophthalic anhydride includes at least one of tetrafluorophthalic anhydride, 3-fluorophthalic anhydride, and 4-fluorophthalic anhydride.

4. The waterborne epoxy resin according to claim 2, characterized in that The molar ratio of the glycidol to bisphenol A is 1:(1-5).

5. A method for preparing the waterborne epoxy resin according to any one of claims 1 to 4, characterized in that: The steps include: The epoxy resin is obtained by reacting glycidol and bisphenol A under the action of a catalyst; and the epoxy resin is reacted with fluorophthalic anhydride to obtain the waterborne epoxy resin.

6. A coating, characterized in that: The invention comprises the waterborne epoxy resin according to any one of claims 1 to 4.

7. The coating according to claim 6, characterized in that The waterborne epoxy resin comprises component A and component B; The component A comprises the following ingredients by weight: 20-35 parts of waterborne epoxy resin, 30-50 parts of filler, 6.9-24.1 parts of additives, 20-35 parts of water; The component B comprises the following ingredients in parts by mass: 2-50 parts of water-based epoxy curing agent, 4.5-21 parts of auxiliary agent, and 35-60 parts of water.

8. The coating according to claim 7, characterized in that The additives of component A include the following components by weight: 0.1-0.5 parts of neutralizer, 0.2-0.6 parts of dispersant, 0.1-0.5 parts of defoamer, 2-10 parts of coloring pigment, 4-10 parts of rust-proof pigment, 0-0.5 parts of wetting agent, and 0.5-2 parts of thickener; And / or, the auxiliary agent of component B comprises the following components by weight: 0.5 to 1 part of anti-flash rust agent, 3 to 15 parts of film-forming auxiliary agent, and 1 to 5 parts of defoaming agent; And / or, the mass ratio of the component A to the component B is (3-8):

1.

9. A method for preparing the coating according to claim 7 or 8, characterized in that: The following steps are involved: The components in component A and component B are mixed separately to obtain the coating.

10. A coating for stainless steel, characterized in that: The preparation raw materials include the coating according to any one of claims 6 to 8.

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