A water-based epoxy emulsion, high-film thickness epoxy primer and preparation method thereof

Abstract

A water-based epoxy emulsion, a high-film thickness epoxy primer and a preparation method thereof, belonging to the technical field of water-based coating processing, a water-based epoxy emulsion, comprising, by weight, 1-2 parts of epoxy component A, 43-50 parts of epoxy resin B, 6-8 parts of cosolvent B, 4-6 parts of emulsifier, 0.1-0.2 parts of dispersant, 35-40 parts of water, and 0.2-0.3 parts of epoxy resin C; a high-film thickness epoxy primer, consisting of component A and component B in a mass ratio of 6-8:1, wherein component A, by weight, comprises: 35-45 parts of water-based epoxy emulsion, 1-2 parts of propylene glycol methyl ether, 0.1-0.2 parts of defoamer, 0.4-0.5 parts of dispersant, 0.1-0.2 parts of wetting and leveling agent, 0.5-1 parts of flash rust preventer, 0.1-0.2 parts of montmorillonite clay, 0.3-0.5 parts of dipropylene glycol butyl ether, 5-8 parts of anti-rust pigment, 3-5 parts of titanium dioxide, 0.1-0.2 parts of carbon black, 20-23 parts of barium sulfate, 24-27 parts of water A, 0.3-0.5 parts of thickener, component B includes: 45-50 parts of epoxy curing agent, 10-15 parts of propylene glycol monomethyl ether, and 45-50 parts of water B. The high film thickness epoxy primer prepared by the water-based epoxy emulsion of the present invention has a limit film thickness of more than 200 μm.

Description

Technical Field

[0001] The invention belongs to the technical field of water-based paint processing, and specifically relates to a water-based epoxy emulsion, a high-film thickness epoxy primer and a preparation method thereof. Background Art

[0002] In industrial paint applications, the use of waterborne epoxy two-components has become an indispensable product. Waterborne epoxy two-components have diverse performance and can meet the diverse market requirements.

[0003] In actual application, epoxy two-component is generally only used as a primer, and the film thickness used has certain limitations. However, for some special products, such as sanitary clean rooms and factory buildings, highly corrosive animal husbandry buildings, chemical buildings with strong corrosive atmosphere, etc., the highly corrosive environment or severe climate will accelerate the aging and peeling of the coating, and high film thickness coating is required. High film thickness primer film coating can improve this, but the maximum film thickness of existing epoxy water-based paint is only about 80μm. If the maximum film thickness is exceeded, surface cracking will occur. Summary of the invention

[0004] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a water-based epoxy emulsion, a high-thickness epoxy primer and a preparation method thereof. The high-thickness epoxy primer prepared by the water-based epoxy emulsion of the present invention can form a paint film with a maximum film thickness of more than 200 μm.

[0005] The specific technical solution adopted by the present invention is:

[0006] A water-based epoxy emulsion, comprising, by weight: 1-2 parts of epoxy component A, 43-50 parts of epoxy resin B, 6-8 parts of cosolvent B, 4-6 parts of emulsifier, 0.1-0.2 parts of dispersant, 35-40 parts of water, and 0.2-0.3 parts of epoxy resin C;

[0007] The epoxy component A is composed of the following components in weight percentage: 62-68% of epoxy resin A, 15-22% of cosolvent A, and 14-20% of diethanolamine;

[0008] The epoxy resin A is a solid epoxy resin with an epoxy equivalent of 450-1000 g / eq;

[0009] The epoxy resin B is a solid epoxy resin with an epoxy equivalent of 450-1000 g / eq;

[0010] The epoxy resin C is a liquid epoxy resin with an epoxy equivalent of 180-190 g / eq.

[0011] Furthermore, the co-solvent A is an alcohol ether co-solvent, and the alcohol ether co-solvent adopts one or two of ethylene glycol butyl ether and propylene glycol methyl ether, and the co-solvent B has the same composition as the co-solvent A.

[0012] A high-thickness epoxy primer, comprising the waterborne epoxy emulsion of the present invention, the high-thickness epoxy primer is composed of component A and component B, the mass ratio of component A to component B is 6-8:1;

[0013] Component A comprises, by weight: 35-45 parts of waterborne epoxy emulsion, 1-2 parts of propylene glycol methyl ether, 0.1-0.2 parts of defoamer, 0.4-0.5 parts of dispersant, 0.1-0.2 parts of wetting and leveling agent, 0.5-1 parts of anti-flash rust agent, 0.1-0.2 parts of montmorillonite clay, 0.3-0.5 parts of dipropylene glycol butyl ether, 5-8 parts of anti-rust pigment, 3-5 parts of titanium dioxide, 0.1-0.2 parts of carbon black, 20-23 parts of barium sulfate, 24-27 parts of water A, and 0.3-0.5 parts of thickener;

[0014] Component B comprises, by weight, 45-50 parts of epoxy curing agent, 10-15 parts of propylene glycol monomethyl ether, and 45-50 parts of water B.

[0015] A method for preparing a high film thickness epoxy primer comprises the following steps:

[0016] A: Preparation of waterborne epoxy emulsion;

[0017] B: According to the proportion of high film thickness epoxy primer, weigh each component and set aside;

[0018] C: Add water A, 40-60% of the defoamer content, dispersant, and propylene glycol methyl ether into a container and stir evenly, then add montmorillonite clay, dipropylene glycol butyl ether, anti-rust pigment, carbon black, titanium dioxide, and barium sulfate, stir evenly to obtain a mixed slurry, grind the mixed slurry to a fineness of ≤25 μm, and obtain an early slurry;

[0019] D: Add the water-based epoxy emulsion, dipropylene glycol butyl ether, the preliminary slurry obtained in step C, the wetting and leveling agent, and the remaining defoaming agent into another container and stir evenly, then add the thickener and stir evenly to obtain component A;

[0020] E: Mix the epoxy curing agent and propylene glycol monomethyl ether evenly, then add water B and stir evenly to obtain component B.

[0021] Further, the preparation of the waterborne epoxy emulsion in step A comprises the following steps:

[0022] A1: Weigh each component according to the proportion of water-based epoxy emulsion and set aside;

[0023] A2: Pour epoxy resin A and co-solvent A into a container, heat until epoxy resin A is completely melted, add diethanolamine and perform amination, and obtain epoxy component A after amination;

[0024] A3: Add epoxy resin B, cosolvent B and emulsifier into another container, heat until epoxy resin B is completely melted, then add dispersant, 30-40% of the total amount of water, epoxy component A obtained in step A2, 30-40% of the total amount of water, and the remaining water in sequence, stirring each time after adding the component, then add epoxy resin C, stir while heating and keeping warm, and obtain a water-based epoxy emulsion after filtering.

[0025] Furthermore, in step A2, diethanolamine is added and the mixture is reacted at 115-125° C. for 1.5-2.5 h for amination.

[0026] Furthermore, the stirring under heating and heat preservation in step A3 is stirring at 85-95° C. and a speed of 500-800 r / min for 2-4 hours.

[0027] Furthermore, the mixed slurry obtained after uniform stirring in step C is stirred at 700-800 r / min for 15-20 min.

[0028] Furthermore, in step E, water B is added and stirred evenly at 400-500 r / min for 10-20 min.

[0029] The beneficial effects of the present invention are:

[0030] 1. In the present invention, the prepared high film thickness primer has a limit film thickness of more than 200 μm. The solid epoxy resin A accounting for about 1-2% of the total mass of the water-based epoxy emulsion is aminated to change its molecular structure so that the molecular structure of the epoxy resin A contains an amine group, and then it is sequentially fused with the solid epoxy resin B, water and other additives in a specific order so that the epoxy resin A with the amine group is evenly dispersed in every corner of the emulsion system, so that the emulsion system obtains a better elongation at break and improves the limit film thickness. Only 1-2% of the solid epoxy resin is aminated because excessive amination of the system epoxy resin will lead to excessive hardness of the system and too fast curing speed, thereby causing the paint film surface to crack easily. Finally, the liquid epoxy resin is added to the emulsion system. At this time, the addition of the liquid epoxy resin will generate fine granular resin particles. The resin particles have good viscosity. While increasing the film thickness, it will also increase the viscosity of the system and reduce the occurrence of cracking, thereby further improving the limit film thickness of the epoxy primer.

[0031] 2. The water-based epoxy emulsion of the present invention has sufficient viscosity and rheology, so the amount of barium sulfate added is reduced in the process of preparing high-thickness epoxy primer, avoiding the cracking of the paint film surface caused by excessive barium sulfate, and also reducing the cost and the content of heavy metals in the epoxy primer.

[0032] 3. In the present invention, when amination is carried out in the preparation process of the water-based epoxy emulsion, the equivalent ratio of epoxy resin A and diethanolamine is ≤1:2, that is, the diethanolamine should be 1 times excessive, so as to ensure that the epoxy resin A can be fully aminated and the amination is more thorough. The formed epoxy resin cured product has higher strength and elongation at break, so that the surface of the prepared high-thickness epoxy primer is not prone to cracks and the maximum film thickness is higher. The amination is carried out at 115-125°C in order to stimulate the activity of the amine group and the epoxy group and improve the curing speed of the amine group and the epoxy group.

[0033] 4. In the present invention, the components of the high film thickness epoxy primer contain a small amount of montmorillonite clay. The excellent properties of montmorillonite clay, such as high dispersibility, adsorption, and adhesion, can make the high film thickness epoxy primer and the part to be applied bond more tightly. In addition, since montmorillonite clay itself is an inorganic salt mineral, does not contain organic matter, and has many excellent properties, the amount of other organic additives used is reduced, saving costs while reducing the VOC content of the system.

[0034] 5. The present invention limits the stirring rate and stirring time of the preparation method. When the stirring rate is too slow, the paint liquid is not easy to disperse and is prone to caking. If the stirring rate is too fast, it is easy to cause emulsion demulsification of the product. The stirring time is to make the components fully mixed and evenly mixed so that the effects of additives, thickeners, etc. can be optimal. If the time is too short, the stirring is uneven. If the time is too long, the product temperature will be high and some additives will volatilize. By limiting the stirring rate and stirring time of the preparation method, it is avoided that the preparation process has an adverse effect on the final performance of the product, thereby providing product comprehensive performance stability. DETAILED DESCRIPTION

[0035] In the present invention, epoxy resin A, epoxy resin B, and epoxy resin C are respectively 904 epoxy resin, 901 epoxy resin, and 128 liquid epoxy resin produced by Nan Ya, Taiwan, China; the emulsifier is Nanjing Xinyi synthetic emulsifier 8910; the dispersant is Allnex 6208 dispersant of the United States; the wetting and leveling agent is a rheological powder additive produced by Hemmings Deqian Company; the flash rust inhibitor is Defors T750 of Hoffman Chemical Company; the rust-proof pigment is modified aluminum tripolyphosphate produced by Hunan Ruishi Technology Development Co., Ltd.; the epoxy curing agent is AQUAEPO-3126 produced by Jiangsu Fuqisen New Materials Co., Ltd.; the mesh number of barium sulfate is 1500 mesh; water A and water B are both deionized water; and other raw materials used, unless otherwise specified, can all be purchased from the market. 1. Specific embodiments

[0037] Example 1

[0038] Preparation of waterborne epoxy emulsion

[0039] A1: weigh 1.5 parts of epoxy component A, 46 parts of epoxy resin B, 7 parts of cosolvent B, 5 parts of emulsifier, 0.15 parts of dispersant, 38 parts of water, and 0.24 parts of epoxy resin C.

[0040] The epoxy component A is composed of 65% by weight of epoxy resin A, 20% of cosolvent A, and 15% of diethanolamine.

[0041] Wherein cosolvent A and cosolvent B are both ethylene glycol butyl ether;

[0042] A2: Pour epoxy resin A and co-solvent A into a reaction kettle and heat to 145°C. Heat until epoxy resin A is completely melted, then cool to 120°C. Add diethanolamine at 120°C for amination for 2h. The equivalent ratio of epoxy resin A to diethanolamine is 1:2. After amination, epoxy component A is obtained.

[0043] A3: Add epoxy resin B, cosolvent B and emulsifier into another reaction kettle, heat to 115°C, wait until epoxy resin B is completely melted, then add dispersant and stir at 2000r / min for 10min, add 35% of the total amount of water and stir at 2000r / min for 30min, add epoxy component A obtained in step A2 and stir at 2000r / min for 5min, add 35% of the total amount of water and stir at 2000r / min for 20min, add the remaining water and stir at 2000r / min for 30min, then add epoxy resin C, stir at 600r / min for 3h at 90°C, and obtain a water-based epoxy emulsion after filtration.

[0044] Preparation of high film thickness epoxy primer

[0045] B: Weigh component A and component B with a mass ratio of 7:1 for later use.

[0046] Component A, in parts by weight, includes: 40 parts of waterborne epoxy emulsion, 1.4 parts of propylene glycol methyl ether, 0.15 parts of defoamer, 0.45 parts of dispersant, 0.13 parts of wetting and leveling agent, 0.8 parts of flash rust inhibitor, 0.15 parts of montmorillonite clay, 0.4 parts of dipropylene glycol butyl ether, 6 parts of anti-rust pigment, 4 parts of titanium dioxide, 0.12 parts of carbon black, 22 parts of barium sulfate, 25 parts of water A, 0.4 parts of thickener,

[0047] Component B, in parts by weight, comprises: 48 parts of epoxy curing agent, 13 parts of propylene glycol monomethyl ether, and 48 parts of water B;

[0048] C: Add water A, 50% of the defoamer content, dispersant, and propylene glycol methyl ether into a mixer and stir at 500 r / min for 10 min, then add montmorillonite clay, dipropylene glycol butyl ether, anti-rust pigment, carbon black, titanium dioxide, and barium sulfate, stir at 750 r / min for 18 min to obtain a mixed slurry, grind the mixed slurry to a fineness of ≤25 μm, and obtain an early slurry;

[0049] D: Add the water-based epoxy emulsion, dipropylene glycol butyl ether, the preliminary slurry obtained in step C, the wetting and leveling agent, and the remaining defoaming agent into another mixer, stir and mix at 450 r / min for 15 minutes, then add the thickener, stir evenly to obtain component A;

[0050] E: The epoxy curing agent and propylene glycol monomethyl ether were stirred at 500 r / min for 10 min, and then water B was added and stirred at 600 r / min for 15 min to obtain component B.

[0051] Example 2

[0052] Preparation of waterborne epoxy emulsion

[0053] A1: weigh 1 part of epoxy component A, 50 parts of epoxy resin B, 8 parts of cosolvent B, 4 parts of emulsifier, 0.2 parts of dispersant, 40 parts of water, and 0.3 parts of epoxy resin C.

[0054] The epoxy component A is composed of 62% by weight of epoxy resin A, 22% of cosolvent A, and 16% of diethanolamine.

[0055] Wherein cosolvent A and cosolvent B are both propylene glycol methyl ether;

[0056] A2: Pour epoxy resin A and co-solvent A into a reaction kettle and heat to 150°C. Heat until epoxy resin A is completely melted, then cool to 115°C. Add diethanolamine at 115°C for amination for 2.5 hours. The equivalent ratio of epoxy resin A to diethanolamine is 1:2.2. After amination, epoxy component A is obtained.

[0057] A3: Add epoxy resin B, cosolvent B and emulsifier into another reaction kettle, heat to 110°C, wait until epoxy resin B is completely melted, then add dispersant and stir at 2000r / min for 12min, add 30% of the total amount of water and stir at 2000r / min for 25min, add epoxy component A obtained in step A2 and stir at 2000r / min for 6min, add 40% of the total amount of water and stir at 2000r / min for 25min, add the remaining water and stir at 2000r / min for 25min, then add epoxy resin C, stir at 800r / min for 2h at 85°C, and obtain a water-based epoxy emulsion after filtration.

[0058] Preparation of high film thickness epoxy primer

[0059] B: Weigh component A and component B with a mass ratio of 6:1 for later use.

[0060] Component A, in parts by weight, includes: 35 parts of water-based epoxy emulsion, 1 part of propylene glycol methyl ether, 0.1 part of defoamer, 0.5 part of dispersant, 0.1 part of wetting and leveling agent, 1 part of anti-flash rust agent, 0.1 part of montmorillonite clay, 0.5 part of dipropylene glycol butyl ether, 8 parts of anti-rust pigment, 5 parts of titanium dioxide, 0.2 parts of carbon black, 23 parts of barium sulfate, 24 parts of water A, 0.5 parts of thickener,

[0061] Component B, in parts by weight, comprises: 45 parts of epoxy curing agent, 10 parts of propylene glycol monomethyl ether, and 50 parts of water B;

[0062] C: Add water A, 40% of the defoamer content, dispersant, and propylene glycol methyl ether into a mixer and stir at 400 r / min for 12 min, then add montmorillonite clay, dipropylene glycol butyl ether, anti-rust pigment, carbon black, titanium dioxide, and barium sulfate, stir at 700 r / min for 20 min to obtain a mixed slurry, grind the mixed slurry to a fineness of ≤25 μm, and obtain an early slurry;

[0063] D: Add the water-based epoxy emulsion, dipropylene glycol butyl ether, the preliminary slurry obtained in step C, the wetting and leveling agent, and the remaining defoaming agent into another mixer and stir and mix at 400 r / min for 20 min, then add the thickener and stir evenly to obtain component A;

[0064] E: The epoxy curing agent and propylene glycol monomethyl ether were stirred at 450 r / min for 14 min, and then water B was added and stirred at 500 r / min for 10 min to obtain component B.

[0065] Example 3

[0066] Preparation of waterborne epoxy emulsion

[0067] A1: weigh 2 parts of epoxy component A, 43 parts of epoxy resin B, 6 parts of cosolvent B, 6 parts of emulsifier, 0.1 parts of dispersant, 35 parts of water, and 0.2 parts of epoxy resin C.

[0068] The epoxy component A is composed of 68% by weight of epoxy resin A, 15% of cosolvent A, and 17% of diethanolamine.

[0069] Wherein cosolvent A and cosolvent B are both ethylene glycol butyl ether;

[0070] A2: Pour epoxy resin A and co-solvent A into a reaction kettle and heat to 145°C. Heat until epoxy resin A is completely melted, then cool to 125°C. Add diethanolamine at 125°C for amination for 1.5h. The equivalent ratio of epoxy resin A to diethanolamine is 1:2. After amination, epoxy component A is obtained.

[0071] A3: Add epoxy resin B, cosolvent B and emulsifier into another reaction kettle, heat to 120°C, wait until epoxy resin B is completely melted, then add dispersant and stir at 2000r / min for 10min, add 40% of the total amount of water and stir at 2000r / min for 20min, add epoxy component A obtained in step A2 and stir at 2000r / min for 5min, add 30% of the total amount of water and stir at 2000r / min for 15min, add the remaining water and stir at 2000r / min for 20min, then add epoxy resin C, stir at 500r / min at 95°C for 2h, and filter to obtain a water-based epoxy emulsion.

[0072] Preparation of high film thickness epoxy primer

[0073] B: Weigh component A and component B with a mass ratio of 8:1 for later use.

[0074] Component A, in parts by weight, includes: 45 parts of waterborne epoxy emulsion, 2 parts of propylene glycol methyl ether, 0.2 parts of defoamer, 0.4 parts of dispersant, 0.2 parts of wetting and leveling agent, 0.5 parts of flash rust inhibitor, 0.2 parts of montmorillonite clay, 0.3 parts of dipropylene glycol butyl ether, 5 parts of anti-rust pigment, 3 parts of titanium dioxide, 0.1 parts of carbon black, 20 parts of barium sulfate, 27 parts of water A, 0.3 parts of thickener,

[0075] Component B, in parts by weight, comprises: 50 parts of epoxy curing agent, 15 parts of propylene glycol monomethyl ether, and 45 parts of water B;

[0076] C: Add water A, 60% of the defoamer content, dispersant, and propylene glycol methyl ether into a mixer and stir at 500 r / min for 8 min, then add montmorillonite clay, dipropylene glycol butyl ether, anti-rust pigment, carbon black, titanium dioxide, and barium sulfate, stir at 800 r / min for 15 min to obtain a mixed slurry, grind the mixed slurry to a fineness of ≤25 μm, and obtain an early slurry;

[0077] D: Add the water-based epoxy emulsion, dipropylene glycol butyl ether, the preliminary slurry obtained in step C2, the wetting and leveling agent, and the remaining defoaming agent into another mixer and stir and mix at 500 r / min for 15 minutes, then add the thickener and stir evenly to obtain component A;

[0078] E: The epoxy curing agent and propylene glycol monomethyl ether were stirred at 500 r / min for 10 min, and then water B was added and stirred at 400 r / min for 20 min to obtain component B.

[0079] Example 4

[0080] Preparation of waterborne epoxy emulsion

[0081] A1: weigh 1.5 parts of epoxy component A, 45 parts of epoxy resin B, 5 parts of cosolvent B, 6 parts of emulsifier, 0.15 parts of dispersant, 38 parts of water, and 0.3 parts of epoxy resin C.

[0082] The epoxy component A is composed of 64% by weight of epoxy resin A, 16% of cosolvent A, and 20% of diethanolamine.

[0083] Wherein, cosolvent A and cosolvent B are mixed cosolvents of ethylene glycol butyl ether and propylene glycol methyl ether in a weight ratio of 1:1;

[0084] A2: Pour epoxy resin A and co-solvent A into a reaction kettle and heat to 148°C. Heat until epoxy resin A is completely melted, then cool to 122°C. Add diethanolamine at 122°C for amination for 1.8h. The equivalent ratio of epoxy resin A to diethanolamine is 1:2.1. After amination, epoxy component A is obtained.

[0085] A3: Add epoxy resin B, cosolvent B and emulsifier into another reaction kettle, heat to 110°C, wait until epoxy resin B is completely melted, then add dispersant and stir at 2000r / min for 8min, add 35% of the total amount of water and stir at 2000r / min for 15min, add epoxy component A obtained in step A2 and stir at 2000r / min for 6min, add 30% of the total amount of water and stir at 2000r / min for 15min, add the remaining water and stir at 2000r / min for 25min, then add epoxy resin C, stir at 750r / min at 92°C for 2.5h, and filter to obtain a water-based epoxy emulsion.

[0086] Preparation of high film thickness epoxy primer

[0087] B: Weigh component A and component B with a mass ratio of 7:1 for later use.

[0088] Component A, in parts by weight, includes: 42 parts of waterborne epoxy emulsion, 1.6 parts of propylene glycol methyl ether, 0.16 parts of defoamer, 0.48 parts of dispersant, 0.15 parts of wetting and leveling agent, 0.8 parts of flash rust inhibitor, 0.14 parts of montmorillonite clay, 0.38 parts of dipropylene glycol butyl ether, 7 parts of anti-rust pigment, 4 parts of titanium dioxide, 0.18 parts of carbon black, 21 parts of barium sulfate, 25 parts of water A, 0.35 parts of thickener,

[0089] Component B, in parts by weight, comprises: 47 parts of epoxy curing agent, 13 parts of propylene glycol monomethyl ether, and 50 parts of water B;

[0090] C: Add water A, 50% of the defoamer content, dispersant, and propylene glycol methyl ether into a mixer and stir at 600 r / min for 5 min, then add montmorillonite clay, dipropylene glycol butyl ether, anti-rust pigment, carbon black, titanium dioxide, and barium sulfate, stir at 750 r / min for 20 min to obtain a mixed slurry, grind the mixed slurry to a fineness of ≤25 μm, and obtain an early slurry;

[0091] D: Add the water-based epoxy emulsion, dipropylene glycol butyl ether, the preliminary slurry obtained in step C, the wetting and leveling agent, and the remaining defoaming agent into another mixer, stir and mix at 450 r / min for 15 minutes, then add the thickener, stir evenly to obtain component A;

[0092] E: The epoxy curing agent and propylene glycol monomethyl ether were stirred at 500 r / min for 12 min, and then water B was added and stirred at 400 r / min for 18 min to obtain component B.

[0093] Example 5

[0094] Preparation of waterborne epoxy emulsion

[0095] A1: weigh 1.8 parts of epoxy component A, 44 parts of epoxy resin B, 5 parts of cosolvent B, 5 parts of emulsifier, 0.1 parts of dispersant, 40 parts of water, and 0.3 parts of epoxy resin C.

[0096] The epoxy component A is composed of 66% by weight of epoxy resin A, 20% of cosolvent A, and 14% of diethanolamine.

[0097] Wherein cosolvent A and cosolvent B are both ethylene glycol butyl ether;

[0098] A2: Pour epoxy resin A and co-solvent A into a reaction kettle and heat to 145°C. Heat until epoxy resin A is completely melted, then cool to 120°C. Add diethanolamine at 120°C for amination for 2h. The equivalent ratio of epoxy resin A to diethanolamine is 1:2. After amination, epoxy component A is obtained.

[0099] A3: Add epoxy resin B, cosolvent B and emulsifier into another reaction kettle, heat to 115°C, wait until epoxy resin B is completely melted, then add dispersant and stir at 2000r / min for 10min, add 35% of the total amount of water and stir at 2000r / min for 15min, add epoxy component A obtained in step A2 and stir at 2000r / min for 5min, add 30% of the total amount of water and stir at 2000r / min for 15min, add the remaining water and stir at 2000r / min for 25min, then add epoxy resin C, stir at 700r / min at 95°C for 3h, and obtain a water-based epoxy emulsion after filtration.

[0100] Preparation of high film thickness epoxy primer

[0101] B: Weigh component A and component B with a mass ratio of 7:1 for later use.

[0102] Component A, in parts by weight, includes: 44 parts of waterborne epoxy emulsion, 1 part of propylene glycol methyl ether, 0.15 parts of defoamer, 0.5 parts of dispersant, 0.2 parts of wetting and leveling agent, 1 part of anti-flash rust agent, 0.2 parts of montmorillonite clay, 0.4 parts of dipropylene glycol butyl ether, 8 parts of anti-rust pigment, 3 parts of titanium dioxide, 0.1 parts of carbon black, 23 parts of barium sulfate, 26 parts of water A, 0.4 parts of thickener,

[0103] Component B, in parts by weight, comprises: 45 parts of epoxy curing agent, 12 parts of propylene glycol monomethyl ether, and 48 parts of water B;

[0104] C: Add water A, 45% of the defoamer content, dispersant, and propylene glycol methyl ether into a mixer and stir at 500 r / min for 10 min, then add montmorillonite clay, dipropylene glycol butyl ether, anti-rust pigment, carbon black, titanium dioxide, and barium sulfate, stir at 700 r / min for 15 min to obtain a mixed slurry, grind the mixed slurry to a fineness of ≤25 μm, and obtain an early slurry;

[0105] D: Add the water-based epoxy emulsion, dipropylene glycol butyl ether, the preliminary slurry obtained in step C, the wetting and leveling agent, and the remaining defoaming agent into another mixer and stir and mix at 500 r / min for 12 minutes, then add the thickener and stir evenly to obtain component A;

[0106] E: The epoxy curing agent and propylene glycol monomethyl ether were stirred at 500 r / min for 10 min, and then water B was added and stirred at 500 r / min for 15 min to obtain component B.

[0107] Comparative Example 1

[0108] The difference between Comparative Example 1 and Example 1 is that the aqueous epoxy emulsion in Comparative Example 1 does not contain epoxy component A.

[0109] Comparative Example 2

[0110] The only difference between Comparative Example 2 and Example 1 is that the aqueous epoxy emulsion in Comparative Example 2 does not contain epoxy resin C.

[0111] Comparative Example 3

[0112] Preparation of waterborne epoxy emulsion

[0113] A1: weigh 1.5 parts of epoxy component A, 46 parts of epoxy resin B, 7 parts of cosolvent B, 5 parts of emulsifier, 0.15 parts of dispersant, 38 parts of water, and 0.24 parts of epoxy resin C.

[0114] The epoxy component A is composed of 76% by weight of epoxy resin A and 34% of cosolvent A.

[0115] Wherein cosolvent A and cosolvent B are both ethylene glycol butyl ether;

[0116] A2: Pour epoxy resin A and co-solvent A into a reaction kettle and heat to 145°C until the epoxy resin A is completely melted to obtain epoxy component A;

[0117] A3: Add epoxy resin B, cosolvent B and emulsifier into another reaction kettle, heat to 115°C, wait until epoxy resin B is completely melted, then add dispersant and stir at 2000r / min for 10min, add 35% of the total amount of water and stir at 2000r / min for 30min, add epoxy component A obtained in step A2 and stir at 2000r / min for 5min, add 35% of the total amount of water and stir at 2000r / min for 20min, add the remaining water and stir at 2000r / min for 30min, then add epoxy resin C, stir at 600r / min for 3h at 90°C, and obtain a water-based epoxy emulsion after filtration.

[0118] The only difference between Comparative Example 3 and Example 1 is that the epoxy resin A in Comparative Example 3 is not aminated, and the other preparation processes of the high film thickness epoxy primer are the same as those in Example 1.

[0119] 2. Performance Test

[0120] The components A and B prepared in the above embodiments and comparative examples were stirred evenly, applied within 30 minutes, and the performance of the obtained paint films was compared. The performance test results are shown in Tables 1-2, wherein the appearance, gloss, flexibility, impact strength, adhesion, pencil hardness, water resistance, water resistance, and salt spray resistance tests were all performed in accordance with the industry standard HG / T4758-2014; the limit film thickness test was performed in accordance with the national standard GB / T 13452.2-92.

[0121] Table 1

[0122]

[0123] Table 2

[0124]

[0125] As can be seen from Table 1, the high-thickness epoxy primers prepared by the preparation method of the present invention in Examples 1-5 have a maximum film thickness of more than 200 μm, a smooth surface, no shrinkage cavities, excellent flexibility, hardness, water resistance and other properties, and good film-forming effect.

[0126] From the comparison between Example 1 and Comparative Examples 1-2, it can be seen that Comparative Example 1 does not contain epoxy component A, and Comparative Example 2 does not contain epoxy resin C. The high film thickness epoxy primer obtained is different from the high film thickness epoxy primer obtained in Example 1 in various properties. This is because three epoxy resins with different equivalents are compounded, and a synergistic enhancement effect is formed between the three epoxy resins, which gives the water-based epoxy emulsion excellent viscosity and is not easy to agglomerate. Therefore, the primer surface formed by the high film thickness epoxy primer prepared by the water-based epoxy emulsion is smooth, and cracking will not occur while increasing the maximum film thickness.

[0127] It can be seen from Example 1 and Comparative Example 3 that the epoxy resin A in Comparative Example 3 is not aminated, while the epoxy resin A in Example 1 is aminated, and the formed epoxy resin cured product has higher strength and elongation at break, making it less likely for cracks to appear on the surface of the prepared high-thickness epoxy primer.

Claims

1. A water-based epoxy emulsion, characterized in that: In parts by weight, it comprises: 1-2 parts of epoxy component A, 43-50 parts of epoxy resin B, 6-8 parts of cosolvent B, 4-6 parts of emulsifier, 0.1-0.2 parts of dispersant, 35-40 parts of water, and 0.2-0.3 parts of epoxy resin C; The epoxy component A is composed of the following components in weight percentage: 62-68% of epoxy resin A, 15-22% of cosolvent A, and 14-20% of diethanolamine; The epoxy resin A is a solid epoxy resin with an epoxy equivalent of 450-1000 g / eq; The epoxy resin B is a solid epoxy resin with an epoxy equivalent of 450-1000 g / eq; The epoxy resin C is a liquid epoxy resin with an epoxy equivalent of 180-190 g / eq; The preparation method of the aqueous epoxy emulsion comprises the following steps: A1: Weigh each component according to the proportion of water-based epoxy emulsion and set aside; A2: Pour epoxy resin A and co-solvent A into a container, heat until epoxy resin A is completely melted, add diethanolamine and react at 115-125°C for 1.5-2.5h for amination, the equivalent ratio of epoxy resin A to diethanolamine is ≤1:2, and epoxy component A is obtained after amination; A3: Add epoxy resin B, cosolvent B and emulsifier into another container, heat until epoxy resin B is completely melted, then add dispersant, 30-40% of the total amount of water, epoxy component A obtained in step A2, 30-40% of the total amount of water, and the remaining water in sequence, stirring each time after adding the component, then add epoxy resin C, stir while heating and keeping warm, and obtain a water-based epoxy emulsion after filtering.

2. The aqueous epoxy emulsion according to claim 1, characterized in that The stirring under heating and heat preservation in step A3 is stirring at 85-95° C. and a rotation speed of 500-800 r / min for 2-4 hours.

3. The aqueous epoxy emulsion according to claim 1, characterized in that The co-solvent A is an alcohol ether co-solvent, and the alcohol ether co-solvent is one or two of ethylene glycol butyl ether and propylene glycol methyl ether. The co-solvent B has the same composition as the co-solvent A.

4. A high film thickness epoxy primer, comprising the waterborne epoxy emulsion according to claim 1, characterized in that: The high film thickness epoxy primer is composed of component A and component B, and the mass ratio of component A to component B is 6-8:1; Component A comprises, by weight: 35-45 parts of the aqueous epoxy emulsion, 1-2 parts of propylene glycol methyl ether, 0.1-0.2 parts of a defoamer, 0.4-0.5 parts of a dispersant, 0.1-0.2 parts of a wetting and leveling agent, 0.5-1 parts of an anti-flash rust agent, 0.1-0.2 parts of montmorillonite clay, 0.3-0.5 parts of dipropylene glycol butyl ether, 5-8 parts of an anti-rust pigment, 3-5 parts of titanium dioxide, 0.1-0.2 parts of carbon black, 20-23 parts of barium sulfate, 24-27 parts of water A, and 0.3-0.5 parts of a thickener; Component B comprises, by weight, 45-50 parts of epoxy curing agent, 10-15 parts of propylene glycol monomethyl ether, and 45-50 parts of water B.

5. The method for preparing a high film thickness epoxy primer according to claim 4, characterized in that: The following steps are involved: A: Preparation of waterborne epoxy emulsion; B: According to the proportion of high film thickness epoxy primer, weigh each component and set aside; C: Add water A, 40-60% of the defoamer content, dispersant, and propylene glycol methyl ether into a container and stir evenly, then add montmorillonite clay, dipropylene glycol butyl ether, anti-rust pigment, carbon black, titanium dioxide, and barium sulfate, stir evenly to obtain a mixed slurry, grind the mixed slurry to a fineness of ≤25 μm, and obtain an early slurry; D: Add the water-based epoxy emulsion, dipropylene glycol butyl ether, the preliminary slurry obtained in step C, the wetting and leveling agent, and the remaining defoaming agent into another container and stir evenly, then add the thickener and stir evenly to obtain component A; E: Mix the epoxy curing agent and propylene glycol monomethyl ether evenly, then add water B and stir evenly to obtain component B.

6. The method for preparing the high film thickness epoxy primer according to claim 5, characterized in that: The mixed slurry obtained after uniform stirring in step C is stirred at 700-800 r / min for 15-20 min.

7. The method for preparing the high film thickness epoxy primer according to claim 5, characterized in that: In step E, water B is added and stirred evenly at 400-500 r / min for 10-20 min.

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