Low-density epoxy primer with strong adhesion to H-grade flash rust surface and preparation method of low-density epoxy primer

Abstract

The invention discloses a low-density epoxy primer with strong adhesion to an H-grade flash rust surface and a preparation method thereof, and relates to the field of paint chemical industry, the epoxy primer comprises a component A and a component B; the component A comprises epoxy resin, double-layer coated hollow glass beads, a thixotropic agent, a wetting dispersant, a pigment, barium sulfate, talcum powder, a solvent A, a defoaming agent, a first silane coupling agent and aluminum paste; and the component B comprises a curing agent, an accelerant and a solvent B. The low-density epoxy primer with strong adhesion to the H-grade flash rust surface has excellent adhesion and excellent corrosion resistance on the surface of a metal base material treated by manual rust removal, mechanical rust removal, water sand blasting rust removal and the like, has higher tolerance on flash rust on the surface treated by water sand blasting rust removal, and can adapt to the H-grade flash rust surface.

Description

Technical Field

[0001] The invention relates to the field of paint chemicals, and more particularly to a low-density epoxy primer with strong adhesion to an H-grade flash rust surface and a preparation method thereof. Background Art

[0002] Steel components, as a metal material, are widely used in various fields such as construction, manufacturing, transportation, aerospace, etc. They are also the core materials of modern shipbuilding industry, mainly used in the manufacture of hull structures, equipment and components. Steel components are generally painted with shop primer or clear oil before leaving the factory, but the protection period of shop primer or clear oil is about 3 to 6 months, while the construction period of steel components is long and the internal corrosion is serious, so the steel structure needs to be rust-proofed.

[0003] Among many rust removal methods, high-pressure water sandblasting is dust-free and low-cost. Therefore, it has gradually become the mainstream choice in the field of rust removal due to its economic, efficient and environmentally friendly characteristics. After high-pressure water sandblasting, the surface of steel components is exposed to the air, and flash rust will occur to varying degrees due to moisture or corrosive substances. Flash rust includes L-level mild flash rust, M-level moderate flash rust and H-level severe flash rust, among which H-level is the most serious flash rust level. H-level severe flash rust is severely corroded, and the surface state shows a dark red-yellow or brown rust layer on the surface of the original steel. The rust layer is thick and loosely attached, and the rust layer is evenly distributed and presents in sheets. After wiping with a cloth, obvious rust marks are shown on the cloth. H-level flash rust seriously affects the adhesion of the coating, causing the coating to peel off or blister. Rust weakens the metal's anti-corrosion ability, shortens the service life, and affects the surface appearance, reducing the product value.

[0004] Chinese patent CN109370380A discloses a high-solid rust-resistant coating and a preparation method, which mainly focuses on environmentally friendly coatings and does not pollute the environment. Chinese patent CN103788829A discloses a heavy-duty anti-corrosion epoxy primer for low-grade substrate treatment, which can be applied on rusty and wet low-grade substrate treated steel. Chinese patent CN103725159A discloses a highly adaptable anti-corrosion coating, which has good adhesion to hot-dip galvanizing, hot-dip galvanizing with rust, rusted steel, and conventional old coatings with epoxy, acrylic acid, and fluorocarbon resin as film-forming materials, and has excellent anti-corrosion, weather resistance, and medium resistance. Chinese patent CN113321987A discloses a high-tolerance epoxy primer for water jet rust removal surfaces, its preparation method, and use. The primer is suitable for moderate or mild flash rust surfaces of steel structures with corrosion inhibitor residues on the surface after water jet rust removal. The coatings involved in the above patents have their own advantages, but none of them are suitable for H-level flash rust surfaces.

[0005] There is no report in the prior art about newly formed flash rust on the surface of high-pressure water sandblasting, and the flash rust grade is H. The salt spray resistance of existing low-surface treatment epoxy primers only reaches 1000 to 1400 hours, which is far from the high salt spray resistance requirement of more than 5000 hours required in heavy corrosion protection applications of ships and marine engineering. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a low-density epoxy primer with strong adhesion to the H-level flash rust surface and a preparation method thereof. The low-density epoxy primer with strong adhesion to the H-level flash rust surface of the present invention has excellent adhesion and excellent anti-corrosion performance on the surface of the metal substrate treated by manual rust removal, mechanical rust removal, water sandblasting rust removal, etc., has a high tolerance for flash rust on the surface treated by water sandblasting rust removal, and can be adapted to the H-level flash rust surface.

[0007] One of the objects of the present invention is to provide a low density epoxy primer having strong adhesion to H-class flash rust surfaces.

[0008] The low-density epoxy primer with strong adhesion to the H-grade flash rust surface of the present invention is made of raw materials including the following components:

[0009] A component and B component;

[0010] Component A includes epoxy resin, double-layer coated hollow glass microspheres, thixotropic agent, wetting dispersant, pigment, barium sulfate, talcum powder, solvent A, defoamer, first silane coupling agent and aluminum powder slurry;

[0011] Component B includes a curing agent, an accelerator and a solvent B;

[0012] In component A, based on 100 parts by weight of the epoxy resin:

[0013]

[0014]

[0015] In component B, based on 100 parts by weight of the curing agent: 100 parts by weight of curing agent;

[0016] 0.5 to 5 parts by weight of accelerator;

[0017] Solvent B 10-50 parts by weight. In a preferred embodiment of the present invention: in component A, based on 100 parts by weight of the epoxy resin:

[0018] In component B, based on 100 parts by weight of the curing agent: 100 parts by weight of curing agent;

[0019] 0.5-2 parts by weight of accelerator;

[0020] Solvent B 10-30 parts by weight;

[0021] The weight ratio of the component A to the component B is 100:(10-50), preferably 100:(12-45).

[0022] In a preferred embodiment of the present invention:

[0023] The double-layer coated hollow glass microspheres are prepared by mixing raw materials including epoxy resin to be modified, rust-capturing filler, isocyanate prepolymer, catalyst and reaction solvent under a protective gas atmosphere.

[0024] In a preferred embodiment of the present invention:

[0025] The weight ratio of the epoxy resin to be modified, the rust-trapping filler and the isocyanate prepolymer is (5-15):(1-5):1, preferably (8-12):(1.5-3.8):1; and / or,

[0026] The amount of the catalyst is 0.01 wt% to 5 wt% of the isocyanate prepolymer, preferably 0.1 wt% to 1 wt%; and / or,

[0027] The amount of the reaction solvent is 20-40wt%, preferably 25-30wt% of the epoxy resin to be modified; and / or,

[0028] The reaction temperature of the mixed reaction is 80° C. to 100° C., preferably 80° C. to 90° C., and / or the reaction time is 1 to 5 hours, preferably 2 to 3 hours.

[0029] In a preferred embodiment of the present invention:

[0030] The rust-capturing filler is prepared by soaking hollow glass microspheres in a solution comprising tannic acid, a second silane coupling agent and a soaking solvent, and then freeze-drying at low temperature; and / or,

[0031] The isocyanate prepolymer is prepared by vacuum dehydrating dimer acid polyester polyol and cooling it, and then prepolymerizing it with isocyanate in a protective gas atmosphere; and / or,

[0032] The epoxy resin to be modified is at least one of bisphenol A epoxy resins, preferably at least one of bisphenol A epoxy resin 618, bisphenol A epoxy resin 6101, bisphenol A epoxy resin 601, and bisphenol A epoxy resin 604; preferably, the epoxy equivalent of the epoxy resin to be modified is 150 to 1000; and / or,

[0033] The catalyst is at least one of sulfuric acid, perchloric acid, sodium methoxide, lithium methoxide, potassium eicosylsulfonate, alkali metal hydroxide, triarylphosphine, triphenylphosphine, stannous octoate, dibutyltin dilaurate, and ferric bromide; and / or,

[0034] The reaction solvent is a mixture of xylene and at least one of butyl acetate, propylene glycol methyl ether acetate, and dipropylene glycol dimethyl ether. Preferably, the mixing weight ratio of xylene to at least one of butyl acetate, propylene glycol methyl ether acetate, and dipropylene glycol dimethyl ether is (1.5-1):1.

[0035] In a preferred embodiment of the present invention:

[0036] The weight ratio of the soaking solvent, tannic acid, the second silane coupling agent and the hollow glass microspheres is (0.4-2):(0.1-0.5):(0.1-0.5):1, preferably (0.8-1.6)(0.2-0.4):(0.25-0.4):1; and / or,

[0037] The weight ratio of the isocyanate to the dimer acid polyester polyol is 1:(0.5-10), preferably 1:(0.9-6).

[0038] In a preferred embodiment of the present invention:

[0039] The standard median particle size of the hollow glass microspheres is 18 to 60 μm, preferably 30 to 50 μm; and / or,

[0040] The tannic acid is tannic acid commonly used in the art, and can be chemically pure or analytically pure; and / or,

[0041] The second silane coupling agent is at least one of vinyl trimethoxy silane, γ-glycidyloxypropyl trimethoxy silane (such as silane coupling agent KH560, silane coupling agent A187), and γ-aminopropyl triethoxy silane (such as KH550 silane coupling agent); and / or,

[0042] The soaking solvent is a mixture of water and ethanol, preferably, the weight ratio of water to ethanol is (0.5-2):1, more preferably (0.6-1.5):1; and / or,

[0043] The isocyanate is at least one of 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, carbodiimide-uretonimine-modified 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and polymethyl polyphenyl isocyanate; and / or,

[0044] The molecular weight of the dimer acid polyester polyol is 1,000 to 10,000.

[0045] In a preferred embodiment of the present invention:

[0046] The soaking temperature is 10 to 50° C., preferably 20 to 40° C., and / or the soaking time is 1 to 4 hours, preferably 2 to 3 hours; and / or,

[0047] The temperature of the low temperature freeze drying is -30°C to -90°C, preferably -40°C to -80°C, and / or the time is 1 to 5 hours, preferably 2 to 4 hours; and / or,

[0048] The vacuum dehydration temperature is 110 to 150° C., and / or the vacuum degree is -0.08 Pa to -0.10 Pa, and / or the time is 0.5 h to 2 h; and / or,

[0049] The temperature after cooling is below 60°C; and / or,

[0050] The reaction temperature of the prepolymerization reaction is 80° C. to 100° C., preferably 80° C. to 90° C., and / or the reaction time is 1 to 4 hours, preferably 2 to 3 hours.

[0051] In a preferred embodiment of the present invention:

[0052] The epoxy resin is at least one of liquid bisphenol A epoxy resins, preferably at least one of bisphenol A epoxy resin 618, bisphenol A epoxy resin 6101, bisphenol A epoxy resin 601, bisphenol A epoxy resin 604, and bisphenol A epoxy resin 618; and / or,

[0053] The thixotropic agent is at least one of organic bentonite, modified hydrogenated castor oil, polyamide wax powder (such as polyamide wax powder ultra, polyamide wax powder 8056, polyamide wax powder OPTIMA), and fumed silica. Preferably, the polyamide wax powder is hydrogenated castor oil modified polyamide wax powder (such as castor oil modified polyamide wax powder ST); and / or,

[0054] The wetting and dispersing agent is at least one of a polyacrylate solution (such as wetting and dispersing agent BYK-S706), a block copolymer with a basic pigment affinity group (such as wetting and dispersing agent BYK-2155), an alkyl ammonium salt type wetting and dispersing agent of a high molecular weight copolymer (such as wetting and dispersing agent BYK-9076), an acrylic dispersant (such as wetting and dispersing agent BYK-359), an organosilicon surfactant, an acid-based copolymer solution (such as wetting and dispersing agent Disponer9250), and an alkyl ammonium salt solution of a polycarboxylic acid (such as wetting and dispersing agent BYK-203); and / or,

[0055] The pigment is at least one of carbon black, red iron oxide, yellow iron oxide, titanium white and phthalocyanine blue; and / or,

[0056] The solvent A is n-butanol and optionally xylene; and / or,

[0057] The defoamer is a commonly used defoamer in the art, such as at least one of defoamer BYK-530, defoamer BYK-085, and defoamer BYK-066; and / or,

[0058] The first silane coupling agent is at least one of vinyl trimethoxy silane, γ-glycidyloxypropyl trimethoxy silane (such as silane coupling agent KH560, silane coupling agent A187), and γ-aminopropyl triethoxy silane (such as silane coupling agent KH550); and / or,

[0059] The aluminum powder paste is a non-leafing aluminum powder paste (such as non-leafing aluminum powder paste 2501); and / or,

[0060] The curing agent is at least one of phenolic amide curing agents (such as phenolic amide curing agent LITE3040, phenolic amide curing agent LITE3025, phenolic amide curing agent LITE3060), preferably a cardanol-modified phenolic amide curing agent; the cardanol-modified phenolic amide curing agent has a relatively long fatty side chain of cardanol and good hydrophobicity, which can make the coating exhibit excellent water resistance and surface tolerance, and at the same time has the advantages of polyamide and phenolic amine, and has a high tolerance to the substrate surface; and / or,

[0061] The accelerator is an epoxy curing accelerator, preferably at least one of triethylenediamine, 2,4,6-tris(dimethylaminomethyl)phenol (accelerator DMP-30), and benzyldimethylamine, more preferably 2,4,6-tris(dimethylaminomethyl)phenol; and / or,

[0062] The solvent B is n-butanol and optionally xylene, preferably a mixture of n-butanol and xylene, more preferably, the weight ratio of n-butanol to xylene is (0.3-1.5):1.

[0063] The second object of the present invention is to provide a method for preparing a low-density epoxy primer that has strong adhesion to a Class H flash rust surface as described in one of the objects of the present invention.

[0064] The method for preparing the low-density epoxy primer with strong adhesion to the H-grade flash rust surface of the present invention comprises:

[0065] The component A is prepared by mixing the component A in the amount described above; the component B is prepared by mixing the component B in the amount described above; and the epoxy primer is prepared by mixing the component A and the component B.

[0066] The preparation method of component A can be specifically as follows:

[0067] (1) Preparation of double-layer coated hollow glass microspheres:

[0068] Step 1: Synthesis of rust-capturing filler (surface modification of hollow glass microspheres): chemically modify the surface of the hollow glass microspheres using a second silane coupling agent and tannic acid, immerse the hollow glass microspheres in a solution including the second silane coupling agent, tannic acid and an immersion solvent, immerse at 10 to 50° C. for 1 to 4 hours, and freeze-dry to remove water and ethanol;

[0069] Step 2: Synthesis of isocyanate prepolymer: remove moisture from dimer acid polyester polyol at 110-150° C. in vacuum, add the dehydrated dimer acid polyester polyol and isocyanate into a reactor under a protective gas atmosphere (nitrogen), maintain the reaction temperature at 80° C.-100° C. for 1-4 hours, measure the isocyanate content, and discharge;

[0070] Step 3: Take another reaction kettle, vacuum dehydrate the epoxy resin to be modified, add the catalyst under stirring, gradually add the synthesized isocyanate prepolymer, gradually heat up to 80-100°C for reaction, then add the synthesized rust capture filler, add the reaction solvent and stir evenly, heat up to 80-100°C for reaction, measure the epoxy value, cool to room temperature, and discharge;

[0071] (2) Use a paint mixing can, add epoxy resin, double-layer coated hollow glass microspheres, and thixotropic agent into it, disperse at high speed for 5 to 10 minutes to make the thixotropic agent thoroughly dispersed, add the wetting dispersant at low speed, and stir evenly;

[0072] (3) Add 80% of solvent A, pigment, talcum powder, and barium sulfate in sequence under low-speed dispersion, stir at high speed for 30 to 50 minutes at 50 to 70° C., disperse to a fineness of ≤80 μm, add the remaining solvent A, defoamer, first silane coupling agent, and aluminum powder slurry, stir evenly, and discharge.

[0073] Compared with the prior art, the present invention has the following beneficial effects:

[0074] 1. The double-layer coated hollow glass microspheres used in the present invention introduce isocyanate prepolymer and rust-capturing filler (modified hollow glass microspheres) into the epoxy resin molecules to be modified, thereby improving the compatibility of the hollow glass microspheres with the epoxy resin to be modified, so that the rust-capturing filler (modified hollow glass microspheres) can be evenly dispersed in the paint solution. Figure 1-3As shown, ① in the initial stage of painting, that is, before curing, when the paint film contacts the low-treated surface, the tannic acid on the surface of the hollow glass microspheres can adsorb the rust on the surface of the substrate and react with it; ② during curing, the hollow glass microspheres use their own low specific gravity to gradually detach the adsorbed reactants from the surface of the substrate and float to the middle or upper layer of the paint liquid; ③ after curing, the rust adsorbed by the hollow glass microspheres can be used as a filler to fill the epoxy resin paint, which does not affect the adhesion of the paint film to the substrate, ensuring a higher adhesion. The epoxy primer of the present invention not only improves the adhesion of the H-level flash rust surface, but also uses the low specific gravity of the hollow glass microspheres themselves to achieve the requirement of lightweight coating.

[0075] 2. The isocyanate prepolymer obtained by prepolymerization of isocyanate and dimer acid polyester polyol used in the present invention increases the molecular crosslinking degree and toughness of the system, improves the reactivity, impact resistance, adhesion and peel strength of the epoxy resin, and enhances the adhesion to the substrate surface.

[0076] 3. The low-density epoxy primer with strong adhesion to the H-grade flash rust surface provided by the present invention can solve the technical problem that the existing technology cannot be used for mechanical rust removal, manual rust removal, water sandblasting rust removal, etc. at the same time; under the conditions of different flash rust levels on the surface after water sandblasting treatment, especially on the H-grade severe flash rust surface, the primer has high adhesion and excellent salt spray resistance. It is suitable for anti-corrosion coating in the fields of ships, bridges, steel structures, etc., especially suitable for direct construction on flash rust surfaces, which simplifies the surface treatment process and improves construction efficiency and economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 It is a schematic diagram of the curing process of the low-density epoxy primer with strong adhesion to the H-level flash rust surface of the present invention;

[0078] Figure 2 It is a microscopic schematic diagram of the curing process of the low-density epoxy primer with strong adhesion to the H-level flash rust surface of the present invention before curing;

[0079] Figure 3 The microscopic schematic diagram of the curing process of the low-density epoxy primer having strong adhesion to the H-class flash rust surface of the present invention. DETAILED DESCRIPTION

[0080] The present invention is described in detail below in conjunction with specific drawings and embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0081] The raw materials used in the examples and comparative examples of the present invention are all conventional commercially available raw materials.

[0082] The test methods used in the embodiments of the present invention and the comparative examples are as follows:

[0083] Density: Tested according to GB / T 6750;

[0084] Salt spray resistance (5000h): tested in accordance with GB / T1771;

[0085] Cathodic stripping resistance (6 months, distance from artificial opening in stripping area): tested in accordance with GB / T7790 standard;

[0086] Adhesion: Tested according to GB / T 5210 standard.

[0087] [Example 1]

[0088] Preparation of component A:

[0089] (1) Preparation of double-layer coated hollow glass microspheres:

[0090] Step 1: Preparation of rust-capturing filler (surface modification of hollow glass microspheres): 20 parts by weight of tannic acid and 25 parts by weight of silane coupling agent KH560 are added to a mixed solution of 80 parts by weight of water and ethanol in a weight ratio of 1:1, and stirred evenly; 100 parts by weight of hollow glass microspheres with a standard median particle size of 30 μm and the mixed liquid are added to a powder mixer, mixed evenly, soaked at 20° C. for 3 hours, and then freeze-dried to remove water and ethanol to obtain rust-capturing filler (modified hollow glass microspheres);

[0091] Step 2: Synthesis of isocyanate prepolymer: 288 parts by weight of dimer acid polyester polyol (functionality 2, molecular weight 1000) was vacuum dehydrated at 120°C for 2 hours, cooled to 60°C, and 100 parts by weight of 2,6-toluene diisocyanate was added under stirring, fully stirred, gradually heated to 80°C, kept warm for 2 hours, and the isocyanate content was measured. The obtained product was an isocyanate prepolymer;

[0092] Step 3: Take another reaction kettle, take 8 parts by weight of bisphenol A epoxy resin 601, 1 part by weight of xylene, and 1 part by weight of dipropylene glycol dimethyl ether, heat to 60°C and stir for half an hour. After fully dissolved, add 1 part by weight of isocyanate prepolymer, stir for 15 minutes, and stir evenly; add 1wt% of stannous octoate of isocyanate prepolymer while stirring, gradually heat to 90°C, and keep warm for 2.5 hours; add 1.5 parts by weight of rust capture filler (modified hollow glass microspheres) while stirring, 90°C, keep warm for 1 hour, measure the epoxy value, and the resulting product is double-layer coated hollow glass microspheres.

[0093] (2) Bisphenol A epoxy resin 618, double-layer coated hollow glass microspheres, barium sulfate, talc, carbon black, titanium dioxide, polyamide wax powder ultra, wetting dispersant BYK-359, defoamer BYK-530, silane coupling agent KH560, xylene, n-butanol, and non-leafing aluminum powder slurry 2501 were mixed in the proportions shown in Table 1 and subjected to high-speed dispersion to obtain component A.

[0094] Preparation of component B:

[0095] Add phenolic acid amide curing agent LITE3040, accelerator DMP-30, xylene and n-butanol into the paint tank according to the ratio shown in Table 1 below, and stir at high speed for 30 minutes using a high-speed shear dispersing device to obtain component B.

[0096] The weight ratio of component A to component B is 100:14.

[0097] Table 1

[0098] Component A Weight Epoxy resin WSR618 100 Double-layer coated hollow glass microspheres 207.9 Barium sulfate 110 talcum powder 140 Titanium dioxide 2.7 Carbon Black 0.31 Non-leafing aluminum paste 2501 40 Polyamide wax powder Ultra 6.8 Silane coupling agent KH560 4.2 Wetting and dispersing agent BYK-359 3 Defoamer BYK530 3.96 Xylene 84.6 n-Butanol 16.4 Component B Phenolic amide curing agent LITE3040 100 Accelerator DMP-30 2 Xylene 5 n-Butanol 5

[0099] [Example 2]

[0100] Preparation of component A:

[0101] (1) Preparation of double-layer coated hollow glass microspheres:

[0102] Step 1: Preparation of rust-capturing filler (surface modification of hollow glass microspheres): 20 parts by weight of tannic acid and 40 parts by weight of silane coupling agent KH560 are added to a mixed solution of 100 parts by weight of water and ethanol in a weight ratio of 1:1, and stirred evenly. 100 parts by weight of hollow glass microspheres with a standard median particle size of 50 μm and the mixed liquid are added to a powder mixer, and mixed evenly. The mixture is soaked at 40° C. for 3 h, and then freeze-dried to remove water and ethanol to obtain rust-capturing filler (modified hollow glass microspheres);

[0103] Step 2: Synthesis of isocyanate prepolymer: 600 parts by weight of dimer acid polyester polyol (functionality 2, molecular weight 2000) were vacuum dehydrated at 120°C for 2 hours, cooled to 60°C, and 100 parts by weight of 2,6-toluene diisocyanate were added under stirring, fully stirred, gradually heated to 80°C, kept warm for 2 hours, and the isocyanate content was determined. The obtained product was an isocyanate prepolymer;

[0104] Step 3: Take another reaction kettle, take 8 parts by weight of bisphenol A epoxy resin 6101, 1 part by weight of xylene, 1 part by weight of dipropylene glycol dimethyl ether, add 1 part by weight of isocyanate prepolymer, stir for 15 minutes, stir thoroughly, add 0.1wt% of dibutyltin dilaurate to isocyanate prepolymer while stirring, gradually heat to 90°C, keep warm for 2.5 hours, add 1.5 parts by weight of rust capture filler (modified hollow glass microspheres) while stirring, 90°C, keep warm for 1 hour; measure the epoxy value, and the resulting product is double-layer coated hollow glass microspheres.

[0105] (2) Bisphenol A epoxy resin 618, double-layer coated hollow glass microspheres, barium sulfate, talcum powder, red iron oxide, polyamide wax powder ultra, wetting dispersant BYK-2155, defoamer BYK-530, silane coupling agent KH560, xylene, n-butanol, and non-leafing aluminum powder slurry 2501 were prepared by high-speed dispersion according to the ratio shown in Table 2 below to obtain component A.

[0106] Preparation of component B:

[0107] Phenolic amide curing agent LITE3040, accelerator DMP-30, xylene and n-butanol were added to the paint can according to the ratio in Table 1, and stirred at high speed for 30 minutes using a high-speed shear dispersing device to obtain component B. The weight ratio of component A to component B was 100:16.

[0108] Table 2

[0109] Component A Weight Epoxy resin WSR618 100 Double-layer coated hollow glass microspheres 150 Barium sulfate 90 talcum powder 125 Iron oxide red 3 Non-leafing aluminum paste 2501 43.8 Polyamide wax powder Ultra 5 Silane coupling agent KH560 6 Wetting and dispersing agent BYK-2155 1.8 Defoamer BYK-530 2 Xylene 121.6 n-Butanol 27.4 Component B Phenolic amide curing agent LITE3040 100 Accelerator DMP-30 2 Xylene 15 n-Butanol 4.6

[0110] [Example 3]

[0111] Preparation of component A:

[0112] (1) Preparation of double-layer coated hollow glass microspheres:

[0113] Step 1: Preparation of rust-capturing filler (surface modification of hollow glass microspheres): 40 parts by weight of tannic acid and 25 parts by weight of silane coupling agent KH560 are added to a mixed solution of 160 parts by weight of water and ethanol in a weight ratio of 1:1, and stirred evenly. 100 parts by weight of hollow glass microspheres with a standard median particle size of 40 μm and the mixed liquid are added to a powder mixer, and mixed evenly. The mixture is soaked at 40° C. for 2 h, and then freeze-dried to remove water and ethanol to obtain rust-capturing filler (modified hollow glass microspheres);

[0114] Step 2: Synthesis of isocyanate prepolymer: 90 parts by weight of dimer acid polyester polyol (functionality 2, molecular weight 2000) was vacuum dehydrated at 120°C for 2 hours, cooled to 60°C, and 100 parts by weight of 2,4'-diphenylmethane diisocyanate was added under stirring, fully stirred, gradually heated to 80°C, kept warm for 2 hours, and the isocyanate content was determined. The obtained product was an isocyanate prepolymer;

[0115] Step 3: Take another reaction kettle, take 12 parts by weight of bisphenol A epoxy resin 6101, 1.8 parts by weight of xylene, 1.2 parts by weight of dipropylene glycol dimethyl ether, heat to 60°C and stir for half an hour. After fully dissolved, add 1 part by weight of isocyanate prepolymer and stir well. Add 0.1wt% of dibutyltin dilaurate to the isocyanate prepolymer while stirring, gradually heat to 90°C, keep warm for 2.5 hours, add 3.8 parts by weight of rust capture filler (modified hollow glass microspheres) while stirring, and heat at 90°C for 1 hour. Measure the epoxy value. The resulting product is double-layer coated hollow glass microspheres.

[0116] (2) Bisphenol A epoxy resin 6101, double-layer coated hollow glass microspheres, talcum powder, barium sulfate, red iron oxide, polyamide wax powder 8056, wetting dispersant BYK-203, defoamer BYK-066, silane coupling agent KH560, xylene, n-butanol, and non-leafing aluminum powder slurry 2501 were prepared by high-speed dispersion in the proportions shown in Table 3 below to obtain component A.

[0117] Preparation of component B:

[0118] Add phenolic acid amide curing agent LITE3025, accelerator DMP-30, xylene and n-butanol into the paint tank according to the ratio shown in Table 3 below, and stir at high speed for 30 minutes using a high-speed shear dispersing device to obtain component B.

[0119] The weight ratio of component A to component B is 100:19.

[0120] Table 3

[0121] Component A Weight Bisphenol A epoxy resin 6101 100 Double-layer coated hollow glass microspheres 250 Barium sulfate 102.3 talcum powder 150 Iron oxide red 3 Non-leafing aluminum paste 2501 60 Polyamide wax powder 8056 6.7 Silane coupling agent KH560 5.4 Wetting and dispersing agent BYK-203 3.7 Defoamer BYK-066 3.1 Xylene 73.8 n-Butanol 10.6 Component B Phenolic amide curing agent LITE3025 100 Accelerator DMP-30 0.8 Xylene 18 n-Butanol 12

[0122] [Example 4]

[0123] Preparation of component A:

[0124] (1) The preparation of double-layer coated hollow glass microspheres is the same as in Example 1;

[0125] (2) Bisphenol A epoxy resin 6101, double-layer coated hollow glass microspheres, talcum powder, barium sulfate, titanium dioxide, carbon black, castor oil modified polyamide wax powder ST, wetting dispersant BYK-203, defoaming agent BYK-066, silane coupling agent KH560, xylene, n-butanol, and non-leafing aluminum powder slurry 2501 were mixed in the proportions shown in Table 4 and subjected to high-speed dispersion to obtain component A.

[0126] Preparation of component B:

[0127] Add phenolic acid amide curing agent LITE3060, phenolic acid amide curing agent LITE3040, accelerator DMP-30, xylene and n-butanol into the paint tank according to the ratio shown in Table 4 below, and stir at high speed for 30 minutes using a high-speed shear dispersing device to obtain component B.

[0128] The weight ratio of component A to component B is 100:12.

[0129] Table 4

[0130] Component A Weight Bisphenol A epoxy resin 6101 100 Double-layer coated hollow glass microspheres 189 Barium sulfate 110.4 talcum powder 120 Titanium dioxide 9.8 Carbon Black 0.2 Non-leafing aluminum paste 2501 60 Castor oil modified polyamide wax powder ST 13 Silane coupling agent KH560 3 Wetting and dispersing agent BYK-203 2.5 Defoamer BYK-066 2.7 Xylene 93.6 n-Butanol 23.9 Component B Phenolic amide curing agent LITE3060 80 Phenolic amide curing agent LITE3040 20 Accelerator DMP-30 0.8 Xylene 12.5 n-Butanol 10

[0131] [Example 5]

[0132] Preparation of component A:

[0133] (1) The preparation of double-layer coated hollow glass microspheres is the same as in Example 3;

[0134] (2) Bisphenol A epoxy resin 618, double-layer coated hollow glass microspheres, barium sulfate, talcum powder, red iron oxide, polyamide wax powder OPTIMA, wetting dispersant BYK-9076, defoamer BYK-085, silane coupling agent A187, xylene, n-butanol, and non-leafing aluminum powder slurry 2501 were prepared by high-speed dispersion according to the ratio shown in Table 5.

[0135] Preparation of component B:

[0136] Add phenolic acid amide curing agent LITE3005, accelerator DMP-30, xylene and n-butanol into the paint tank according to the ratio shown in Table 5 below, and stir at high speed for 30 minutes using a high-speed shear dispersing device to obtain component B.

[0137] The weight ratio of component A to component B is 100:44.

[0138] Table 5

[0139] Component A Weight Bisphenol A epoxy resin 618 100 Double-layer coated hollow glass microspheres 232.6 Barium sulfate 120 talcum powder 130.5 Wetting and dispersing agent BYK-9076 1.2 Iron oxide red 5 Polyamide wax powder OPTIMA 8.1 Non-leafing aluminum paste 2501 50.3 Silane coupling agent A187 4.2 Defoamer BYK-085 2.1 Xylene 87.4 n-Butanol 12.8 Component B Phenolic amide curing agent LITE3005 100 Accelerator DMP-30 0.5 Xylene 9.5 n-Butanol 5.3

[0140] [Comparative Example 1]

[0141] Compared with Example 1, Comparative Example 1 did not use double-layer coated hollow glass microspheres, but replaced them with an equal amount of epoxy resin 601. The specific preparation method is as follows:

[0142] Preparation of component A:

[0143] Bisphenol A epoxy resin 618, bisphenol A epoxy resin 601, barium sulfate, talc, carbon black, titanium dioxide, polyamide wax powder ultra, wetting dispersant BYK-359, defoamer BYK-530, silane coupling agent KH560, xylene, n-butanol, non-leafing aluminum powder slurry 2501 were mixed according to the ratio shown in Table 6 and subjected to high-speed dispersion to obtain component A.

[0144] Preparation of component B:

[0145] Add phenolic acid amide LITE3040, accelerator DMP-30, xylene and butanol into the paint tank according to the ratio shown in Table 6 below, and stir at high speed for 30 minutes using a high-speed shear dispersing device to obtain component B.

[0146] The weight ratio of component A to component B is 100:17.3.

[0147] Table 6

[0148] Component A Weight Bisphenol A epoxy resin 618 100 Bisphenol A epoxy resin 601 207.9 Barium sulfate 110 talcum powder 140 Titanium dioxide 2.7 Carbon Black 0.31 Non-leafing aluminum paste 2501 40 Polyamide wax powder Ultra 6.8 Silane coupling agent KH560 4.2 Wetting and dispersing agent BYK-359 3 Defoamer BYK530 3.96 Xylene 84.6 n-Butanol 16.4 Component B Phenolic amide curing agent LITE3040 100 Accelerator DMP-30 2 Xylene 5 n-Butanol 5

[0149] Sample preparation:

[0150] 1. Substrate treatment:

[0151] Thoroughly remove grease with a suitable cleaning agent and wash with (high pressure) fresh water to remove salt and other contaminants. Sandblast to Sa2.5 (ISO8501-1:2007), surface roughness equivalent to Rugotest No.3N9a to N10, Keane-Tator comparison plate 2.0 (sandblasting / shot peening), or ISO comparison plate fine medium roughness (sandblasting); or water jet blasting to Wa2-Wa2.5 (atmospheric exposure) / minimum Wa2.5 (immersion) (ISO8501-1:2007). Before construction, refer to standard ISO 8501-4:2006 for flash rust classification.

[0152] Flash rust is a visible appearance of steel surface after water spraying. Refer to standard GB / T8923.4-2013 (same as ISO8501-4:2006). Flash rust is divided into three grades according to the degree of flash rust: L, M, H.

[0153] 2. Preparation of paint film:

[0154] Examples 1-5 and Comparative Example 1 were mixed according to the weight ratio of components A and B and stirred thoroughly. The density of the coating was tested in a constant temperature and humidity spray room, and the paint film was sprayed using a high-pressure airless sprayer. The preparation requirements of the paint film (including thickness, etc.) were prepared in accordance with the corresponding test standards, and the relevant properties of the paint film were tested.

[0155] (1) Density test data is shown in Table 7 below:

[0156] Table 7

[0157]

[0158] (2) Salt spray resistance (5000h) test data are shown in Table 8 below:

[0159] Table 8

[0160]

[0161] (3) Cathodic disbonding resistance (6 months) test data are shown in Table 9 below:

[0162] Table 9

[0163]

[0164] (4) Adhesion test data are shown in Table 10 below:

[0165] Table 10

[0166]

[0167] It can be seen from the test data of the above-mentioned Examples 1-5 and Comparative Example 1 that the introduction of double-layer coated hollow glass microspheres can significantly reduce the density of the coating, and the density of the epoxy primer prepared by the present invention is 84.5% to 86.5% of that of Comparative Example 1. The introduction of isocyanate prepolymers with isocyanate and dimer acid structures and modified glass microspheres into the epoxy resin molecules of the double-layer coated hollow glass microspheres in the embodiments of the present invention improves the medium resistance of the coating, especially the surface of M-grade and H-grade steel structures subjected to water sandblasting, and the salt spray resistance and cathodic stripping performance are significantly improved. The paint film with salt spray resistance for more than 5000 hours does not bubble, fall off, or rust; the distance at the artificial opening of the stripping area after 6 months of cathodic stripping is significantly reduced, from 19mm in Comparative Example 1 to less than 8mm; the adhesion is significantly improved, from 3.5MPa in Comparative Example 1 to more than 6MPa.

[0168] The epoxy primer prepared in Example 155 of the present invention has a low density, which effectively realizes lightweight coating, and has excellent adhesion, salt spray resistance, and cathodic stripping resistance on surfaces treated by manual rust removal, mechanical rust removal, water sandblasting, etc. It has a high tolerance for flash rust on surfaces treated by water sandblasting, and can be adapted to H-level flash rust surfaces.

Claims

1. A low-density epoxy primer with strong adhesion to H-grade flash rust surfaces, characterized in that The epoxy primer is prepared from raw materials including the following components: A component and B component; Component A includes epoxy resin, double-layer coated hollow glass microspheres, thixotropic agent, wetting dispersant, pigment, barium sulfate, talcum powder, solvent A, defoamer, first silane coupling agent and aluminum powder slurry; Component B includes a curing agent, an accelerator and a solvent B; In component A, based on 100 parts by weight of the epoxy resin: In component B, based on 100 parts by weight of the curing agent: 100 parts by weight of curing agent; 0.5 to 5 parts by weight of accelerator; Solvent B 10-50 parts by weight.

2. The epoxy primer according to claim 1, characterized in that: In component A, based on 100 parts by weight of the epoxy resin: In component B, based on 100 parts by weight of the curing agent: 100 parts by weight of curing agent; 0.5-2 parts by weight of accelerator; Solvent B 10-30 parts by weight; The weight ratio of the component A to the component B is 100:(10-50), preferably 100:(12-45).

3. The epoxy primer according to claim 1 or 2, characterized in that: The double-layer coated hollow glass microspheres are prepared by mixing raw materials including epoxy resin to be modified, rust-capturing filler, isocyanate prepolymer, catalyst and reaction solvent under a protective gas atmosphere.

4. The epoxy primer according to claim 3, characterized in that: The weight ratio of the epoxy resin to be modified, the rust-trapping filler and the isocyanate prepolymer is (5-15):(1-5):1, preferably (8-12):(1.5-3.8):1; and / or, The amount of the catalyst is 0.01 wt% to 5 wt% of the isocyanate prepolymer, preferably 0.1 wt% to 1 wt%; and / or, The amount of the reaction solvent is 20-40wt%, preferably 25-30wt% of the epoxy resin to be modified; and / or, The reaction temperature of the mixed reaction is 80° C. to 100° C., preferably 80° C. to 90° C., and / or the reaction time is 1 to 5 hours, preferably 2 to 3 hours.

5. The epoxy primer according to claim 3, characterized in that: The rust-capturing filler is prepared by soaking hollow glass microspheres in a solution comprising tannic acid, a second silane coupling agent and a soaking solvent, and then freeze-drying at low temperature; and / or, The isocyanate prepolymer is prepared by vacuum dehydrating dimer acid polyester polyol and cooling it, and then prepolymerizing it with isocyanate in a protective gas atmosphere; and / or, The epoxy resin to be modified is at least one of bisphenol A epoxy resins; preferably, the epoxy equivalent of the epoxy resin to be modified is 150 to 1000; and / or, The catalyst is at least one of sulfuric acid, perchloric acid, sodium methoxide, lithium methoxide, potassium eicosylsulfonate, alkali metal hydroxide, triarylphosphine, triphenylphosphine, stannous octoate, dibutyltin dilaurate, and ferric bromide; and / or, The reaction solvent is a mixture of xylene and at least one of butyl acetate, propylene glycol methyl ether acetate, and dipropylene glycol dimethyl ether. Preferably, the mixing weight ratio of xylene to at least one of butyl acetate, propylene glycol methyl ether acetate, and dipropylene glycol dimethyl ether is (1.5-1):

1.

6. The epoxy primer according to claim 5, characterized in that: The weight ratio of the tannic acid, the second silane coupling agent and the hollow glass microspheres is (0.1-0.5):(0.1-0.5):1, preferably (0.2-0.4):(0.25-0.4):1; and / or, The weight ratio of the soaking solvent, tannic acid, the second silane coupling agent and the hollow glass microspheres is (0.4-2):(0.1-0.5):(0.1-0.5):1, preferably (0.8-1.6)(0.2-0.4):(0.25-0.4):1; and / or, The weight ratio of the isocyanate to the dimer acid polyester polyol is 1:(0.5-10), preferably 1:(0.9-6).

7. The epoxy primer according to claim 5, characterized in that: The standard median particle size of the hollow glass microspheres is 18 to 60 μm, preferably 30 to 50 μm; and / or, The second silane coupling agent is at least one of vinyl trimethoxy silane, γ-glycidyloxypropyl trimethoxy silane, and γ-aminopropyl triethoxy silane; and / or, The soaking solvent is a mixture of water and ethanol, preferably, the weight ratio of water to ethanol is (0.5-2):1, more preferably (0.6-1.5):1; and / or, The isocyanate is at least one of 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, carbodiimide-uretonimine-modified 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and polymethyl polyphenyl isocyanate; and / or, The molecular weight of the dimer acid polyester polyol is 1,000 to 10,000.

8. The epoxy primer according to claim 5, characterized in that: The soaking temperature is 10 to 50° C., preferably 20 to 40° C., and / or the soaking time is 1 to 4 hours, preferably 2 to 3 hours; and / or, The temperature of the low temperature freeze drying is -30°C to -90°C, preferably -40°C to -80°C, and / or the time is 1 to 5 hours, preferably 2 to 4 hours; and / or, The vacuum dehydration temperature is 110 to 150° C., and / or the vacuum degree is -0.08 Pa to -0.10 Pa, and / or the time is 0.5 h to 2 h; and / or, The temperature after cooling is below 60°C; and / or, The reaction temperature of the prepolymerization reaction is 80° C. to 100° C., preferably 80° C. to 90° C., and / or the reaction time is 1 to 4 hours, preferably 2 to 3 hours.

9. The epoxy primer according to claim 1 or 2, characterized in that: The epoxy resin is at least one of liquid bisphenol A epoxy resins; and / or, The thixotropic agent is at least one of organic bentonite, modified hydrogenated castor oil, polyamide wax powder, and fumed silica; and / or, The wetting and dispersing agent is at least one of a polyacrylate solution, a block copolymer containing a basic pigment affinity group, an alkylammonium salt-type wetting and dispersing agent of a high molecular weight copolymer, an acrylic dispersant, an organosilicon surfactant, an acid-containing copolymer solution, and an alkylammonium salt solution of a polycarboxylic acid; and / or, The pigment is at least one of carbon black, red iron oxide, yellow iron oxide, titanium white and phthalocyanine blue; and / or, The solvent A is n-butanol and optionally xylene, preferably a mixture of n-butanol and xylene, more preferably, the weight ratio of n-butanol to xylene is (0.1-1):1; and / or, The first silane coupling agent is at least one of vinyl trimethoxy silane, γ-glycidyloxypropyl trimethoxy silane, and γ-aminopropyl triethoxy silane; and / or, The aluminum slurry is a non-leafing aluminum slurry; and / or, The curing agent is at least one of phenolic acid amide curing agents, preferably a cardanol-modified phenolic acid amide curing agent; and / or, The accelerator is an epoxy curing accelerator, preferably at least one of triethylenediamine, 2,4,6-tris(dimethylaminomethyl)phenol, and benzyldimethylamine; and / or, The solvent B is n-butanol and optionally xylene, preferably a mixture of n-butanol and xylene, more preferably, the weight ratio of n-butanol to xylene is (0.3-1.5):

1.

10. A method for preparing a low-density epoxy primer having strong adhesion to a Class H flash rust surface as claimed in any one of claims 1 to 9, characterized in that The method comprises: The component A is prepared by mixing the component A in the amount described above; the component B is prepared by mixing the component B in the amount described above; and the epoxy primer is prepared by mixing the component A and the component B.

Images