Emulsifier for curing agent, curing agent and preparation method thereof

Abstract

The invention discloses an emulsifier for curing agent, a curing agent and a preparation method thereof, and relates to the technical field of emulsions. The raw materials for preparing the emulsifier include: fatty amine A, polyethylene glycol diglycidyl ether and epoxy resin; the molar mass ratio of the fatty amine A to the sum of polyethylene glycol diglycidyl ether and epoxy resin is 4:(2.2-3). The emulsifier has the characteristics of a long activation period, can effectively prolong the activation period after the curing agent and epoxy resin are compounded, and can effectively improve the salt spray performance and water resistance of the paint film.

Description

Technical Field

[0001] The invention relates to the technical field of emulsions, and in particular to an emulsifier for a curing agent, a curing agent and a preparation method thereof. Background Art

[0002] Waterborne epoxy resin is a widely used resin with excellent adhesion and high chemical resistance. It can be directly applied to metal without primer or other coatings. When in use, waterborne epoxy resin needs to be compounded with curing agent before forming a paint film. In order to meet environmental protection requirements, many manufacturers currently choose waterborne curing agent, but the waterborne curing agent with better performance for epoxy resin is mainly imported, expensive, and the supply is unstable.

[0003] In addition, the existing preparation methods of epoxy resin water-based curing agents basically use fatty amines, monoepoxy compounds and epoxy resins as raw materials, wherein the monoepoxy compounds are used to consume the primary amine hydrogen of the fatty amines to play a capping role, and the curing agent is finally obtained by acid-adding salt. In the above-mentioned preparation method, the use of monoepoxy compounds to cap the curing agent during preparation will affect the hardness and cross-linking density of the subsequent epoxy resin paint film, while the use of acid-adding salt will affect the salt spray performance and water resistance of the epoxy resin system after film formation.

[0004] In addition, the existing curing agent has the problems of short working life and complicated preparation process. If the working life of the curing agent is short, it will cause the curing agent to cure too quickly after compounding with the epoxy resin, which is not conducive to on-site construction. It can be seen that the existing technology still needs to be improved and enhanced. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide an emulsifier for a curing agent, a curing agent and a preparation method thereof, aiming to solve the technical problems in the prior art that the curing agent has a short application period, a complicated preparation process, and insufficient salt spray performance and water resistance of the paint film after the curing agent is compounded with an epoxy resin.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] An emulsifier for a curing agent, the preparation raw materials of which include: fatty amine A, polyethylene glycol diglycidyl ether and epoxy resin; the molar mass ratio of the fatty amine A to the sum of polyethylene glycol diglycidyl ether and epoxy resin is 4:(2.2-3).

[0008] The emulsifier, wherein the molar mass ratio of the fatty amine A to polyethylene glycol diglycidol is 4:(1.8-2).

[0009] The emulsifier, wherein the fatty amine A includes at least one of isophorone diamine, polyether amine, meta-xylylenediamine, ethylenediamine, diethylenetriamine, triethylenetetramine, and 1,3-cyclohexanedimethylamine.

[0010] The emulsifier, wherein the epoxy equivalent of the polyethylene glycol diglycidyl ether is 200 to 1000 g / mol.

[0011] A curing agent, the raw materials for preparing the curing agent include: an intermediate and the emulsifier as described above, wherein the weight ratio of the emulsifier to the intermediate is 15:100 to 35:100; the raw materials for preparing the intermediate include: aliphatic amine B and epoxy resin.

[0012] The curing agent, wherein the molar mass ratio of the fatty amine B to the epoxy resin is 2:(0.9-1.2).

[0013] The curing agent, wherein the fatty amine B includes at least one of meta-xylylenediamine and isophoronediamine.

[0014] A method for preparing a curing agent is used to prepare the curing agent as described above, comprising the following steps: mixing an intermediate with an emulsifier, adding water dropwise, and obtaining the curing agent through phase inversion.

[0015] The preparation method of the curing agent, wherein the preparation method of the emulsifier comprises the following steps: firstly, adding fatty amine A into a reactor, filling with nitrogen, heating to 50-70°C, dripping polyethylene glycol diglycidyl ether, and keeping the temperature for 3-5 hours after the dripping is completed, and then dripping epoxy resin, and keeping the temperature for 3-5 hours after the dripping is completed, to obtain the emulsifier.

[0016] The preparation method of the curing agent, wherein the preparation method of the intermediate comprises the following steps: firstly adding aliphatic amine B into a reactor, filling with nitrogen, heating to 50-70°C, adding a solvent, and then dripping epoxy resin, after the dripping is completed, keeping the temperature at 50-70°C for 2h to obtain the intermediate.

[0017] Beneficial effects:

[0018] The present invention provides an emulsifier for a curing agent, wherein the emulsifier has relatively low reactivity and a long activation period, and is applied to the preparation of a curing agent to effectively extend the applicable period after the curing agent and epoxy resin are compounded. In addition, the preparation method of the emulsifier provided by the present invention is simple, does not require high temperature and a catalyst, has a fast reaction speed and is short in time.

[0019] The present invention also provides a curing agent, which includes a highly reactive intermediate and an emulsifier with a long activation period, has a long application period, and is conducive to on-site construction. In addition, after the curing agent of the present invention is compounded with an epoxy resin, the salt spray performance and water resistance of the paint film can be effectively improved, and the activation period can be extended, and the drying speed of the paint film is faster during use.

[0020] The present invention also provides a method for preparing the curing agent. The preparation method is simple, does not require high temperature and a catalyst, has high safety, low energy consumption, and is short in time. DETAILED DESCRIPTION

[0021] The present invention provides an emulsifier for a curing agent, a curing agent and a preparation method thereof. In order to make the purpose, technical scheme and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the following examples. It should be understood that the specific examples described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] The present invention provides an emulsifier for a curing agent, and the raw materials for preparing the emulsifier include: fatty amine A, polyethylene glycol diglycidyl ether and epoxy resin; the molar mass ratio of the fatty amine A to the sum of polyethylene glycol diglycidyl ether and epoxy resin is 4:(2.2-3). When the amount of fatty amine A is too much, a large amount of unreacted fatty amine A will exist, and the application of the fatty amine A to the curing agent will affect the performance of the curing agent; if the amount of fatty amine A is too little, gel is easily formed when preparing the emulsifier, which is not conducive to production.

[0023] The emulsifier of the present invention has a good emulsifying effect on the intermediate, and the curing agent emulsion can obtain a smaller particle size. In addition, the reaction activity of the emulsifier is lower than that of the intermediate, so that the curing agent and the epoxy resin can have a longer activation period after compounding.

[0024] Preferably, the molar mass ratio of the fatty amine A to the polyethylene glycol diglycidol is 4:(1.8-2). Within this ratio range, the hydrophilicity of the emulsifier is optimal, neither too strong nor too weak, and the overall performance of the curing agent is optimal.

[0025] The fatty amine A includes at least one of isophorone diamine, polyether amine, meta-xylylenediamine, ethylenediamine, diethylenetriamine, triethylenetetramine, and 1,3-cyclohexanedimethylamine.

[0026] The improved emulsifier of the present invention has good emulsification effect, long activation period and simple preparation process, which can effectively prolong the applicable period of the curing agent and simplify its preparation process. The fatty amine A and polyethylene glycol diglycidyl ether are used as the hydrophilic end, and the epoxy resin is used as the lipophilic end, which can play a good emulsification role on the components in the curing agent.

[0027] Preferably, the epoxy equivalent of the polyethylene glycol diglycidyl ether is 200 to 1000 g / mol. If the epoxy equivalent of the polyethylene glycol diglycidyl ether is lower than 200 g / mol, the polyether segment is shorter, the hydrophilicity is poor, and the emulsification effect of the emulsifier is poor; if the epoxy equivalent of the polyethylene glycol diglycidyl ether is higher than 1000 g / mol, the polyethylene glycol diglycidyl ether is too hydrophilic, which affects the salt spray resistance and water resistance of the curing agent.

[0028] Preferably, the epoxy equivalent of the epoxy resin is 180 to 800 g / mol.

[0029] When the epoxy equivalent of epoxy resin is lower than 180 g / mol, the lipophilicity is insufficient and the price is expensive. If it is higher than 800 g / mol, the viscosity and lipophilicity are too high, and the prepared emulsifier has poor emulsification performance for epoxy curing agent.

[0030] Preferably, the epoxy resin is bisphenol A epoxy resin.

[0031] The present invention also provides a curing agent for waterborne epoxy resin, the raw materials for its preparation include: an intermediate and the emulsifier as described above; the weight ratio of the emulsifier to the intermediate is 15:100 to 35:100; the raw materials for the preparation of the intermediate include: fatty amine B and epoxy resin. The curing agent is not capped with a monoepoxy compound, and can avoid the reduction of salt spray resistance and water resistance of the paint film after being compounded with the epoxy resin.

[0032] If the weight ratio of the emulsifier to the intermediate is less than 15:100, the water-based curing agent cannot be well dispersed. If it is greater than 35:100, the water resistance and chemical resistance of the water-based epoxy resin will be greatly reduced due to its strong hydrophilicity.

[0033] Preferably, the molar mass ratio of the fatty amine B to the epoxy resin is 2:(0.9-1.2).

[0034] When the amount of epoxy resin used is too much, gel is easily formed during preparation and the process is difficult to control. When the amount of epoxy resin used is too little, a large amount of fatty amine B will not participate in the reaction, which will affect the performance of the curing agent.

[0035] Preferably, in the intermediate, the epoxy resin is bisphenol A epoxy resin.

[0036] Preferably, the fatty amine includes at least one of m-xylylenediamine and isophorone diamine. After the intermediates prepared from m-xylylenediamine and isophorone diamine and epoxy resin react with the emulsifier of the present invention, the resulting curing agent has a long activation period and good comprehensive properties such as salt spray resistance and water resistance.

[0037] The method for preparing the curing agent for waterborne epoxy resin comprises the following steps: mixing the intermediate as described above with an emulsifier, and preparing the curing agent by phase inversion.

[0038] The specific steps of the phase inversion preparation method are as follows:

[0039] S1. Add the intermediate and emulsifier into the reactor, mix, increase the temperature, and control the temperature not to exceed 70°C;

[0040] S2. Stir at high speed and add deionized water to form a dispersion; while adding deionized water, continuously measure the dispersion, take a dispersion sample and add it dropwise into 80°C hot water. When the dispersion sample can be quickly and evenly dispersed in the hot water, stop adding deionized water and keep stirring at high speed for 1 hour;

[0041] S3. Add the remaining deionized water dropwise while stirring to adjust the viscosity and solid content of the system to obtain a curing agent.

[0042] The weight ratio of the sum of the intermediate and the emulsifier to deionized water is 4:(3-8). If the amount of deionized water is too little, the phase inversion point cannot be reached, and the viscosity of the prepared curing agent is very high, which is not conducive to construction. If the amount of deionized water is too much, the viscosity of the curing agent is too low, and the storage stability at room temperature is poor.

[0043] The preparation method of the emulsifier comprises the following steps: firstly, adding fatty amine A into a reactor, filling with nitrogen, heating to 50-70°C, dropping polyethylene glycol diglycidyl ether, keeping warm for 3-5h after the dropping is complete, then dropping epoxy resin, keeping warm for 3-5h after the dropping is complete, and obtaining the emulsifier.

[0044] The preparation method of the intermediate comprises the following steps: firstly, adding fatty amine B into a reactor, filling with nitrogen, heating to 50-70°C, adding a solvent, and then dripping epoxy resin, and after the dripping is completed, keeping the temperature at 50-70°C for 2h to obtain the intermediate.

[0045] The solvent may be one or more of propylene glycol methyl ether, ethylene glycol butyl ether, diacetone alcohol, and xylene. The solvent is used to reduce viscosity and prevent the generation of gel.

[0046] Preferably, the solid content of the curing agent emulsion is 30% to 60%.

[0047] Preferably, the total active hydrogen equivalent of the curing agent emulsion is 200 to 1000 g / mol.

[0048] Preferably, the viscosity of the curing agent emulsion at 25° C. is 100 to 10,000 cps.

[0049] The curing agent emulsion for waterborne epoxy resin of the present invention has the advantages of simple preparation process, small particle size, wide range of active hydrogen equivalent, small emulsifier content, rapid curing, long activation period, low cost and the like.

[0050] The following examples are given to illustrate the present invention:

[0051] Example 1

[0052] A curing agent, the preparation method of which comprises the following steps:

[0053] A1. Preparation of emulsifier: Add fatty amine A to reactor A, open stirring and fill with nitrogen, heat, raise the temperature to 60 ° C, and then add polyethylene glycol diglycidyl ether dropwise to reactor A at a rate of 1 g / min. After the addition is complete, keep warm for 4 hours, and then add epoxy resin dropwise at a rate of 1 g / min to obtain an emulsifier;

[0054] The molar mass ratio of the fatty amine A to the sum of polyethylene glycol diglycidyl ether and epoxy resin is 4:3; the molar mass ratio of the fatty amine A to polyethylene glycol diglycidol is 4:2.

[0055] Wherein, the fatty amine A is a polyetheramine, and the product model is D230 (Huntsman);

[0056] The product model of the epoxy resin is DER331 (Lan Ke Chemical);

[0057] A2. Preparation of intermediate: Add fatty amine B to reactor B, open stirring and fill with nitrogen, heat, raise the temperature to 60 ° C, add propylene glycol methyl ether as a solvent, continue to slowly add epoxy resin to reactor B, after completion of the addition, keep warm at 60 ° C for 2h to obtain an intermediate;

[0058] The molar mass ratio of the fatty amine B to the epoxy resin is 2:1.2.

[0059] The fatty amine B is m-xylylenediamine;

[0060] The epoxy equivalent of the epoxy resin is 182 g / mol, and the product model is DER331 (Lanke Chemical);

[0061] A3. Preparation of curing agent: Add 20g of emulsifier and 100g of intermediate into reactor C ( The weight ratio of emulsifier to intermediate is 20:100 ), add 100 g of deionized water at a temperature of 50°C and a stirring speed of 500 rpm to form a dispersion, and continuously measure the dispersion during the dropwise addition. Take a dispersion sample and add it dropwise into hot water at 80°C. When the dispersion sample can be quickly and evenly dispersed in the hot water, add 80 g of deionized water and keep stirring for 1 hour to obtain a curing agent emulsion for water-based epoxy resin.

[0062] Example 2

[0063] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0064] Step A1. In the preparation of the emulsifier, the fatty amine A is isophorone diamine; the product model of the epoxy resin is DER671 (Lanke Chemical);

[0065] In step A2. the preparation of the intermediate, the fatty amine B is also isophoronediamine.

[0066] Example 3

[0067] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0068] In step A2. the preparation of the intermediate, the fatty amine B is polyetheramine D230.

[0069] Example 4

[0070] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0071] In step A2. the preparation of the intermediate, the fatty amine B is ethylenediamine.

[0072] Example 5

[0073] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0074] In step A2. the preparation of the intermediate, the fatty amine is diethylenetriamine.

[0075] Example 6

[0076] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0077] In step A2. the preparation of the intermediate, the fatty amine B is triethylenetetramine.

[0078] Example 7

[0079] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0080] In step A2. the preparation of the intermediate, the fatty amine B is 1,3-cyclohexanedimethylamine (1,3-BAC).

[0081] Example 8

[0082] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0083] In step A1. the preparation of the emulsifier, the molar mass ratio of the fatty amine A to the sum of polyethylene glycol diglycidyl ether and the epoxy resin is 4:1.8.

[0084] Example 9

[0085] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0086] In step A1. the preparation of the emulsifier, the molar mass ratio of the fatty amine A to the sum of polyethylene glycol diglycidyl ether and the epoxy resin is 4:2.

[0087] Example 10

[0088] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0089] In step A1. the preparation of the emulsifier, the molar mass ratio of the fatty amine A to the sum of polyethylene glycol diglycidyl ether and the epoxy resin is 4:2.2.

[0090] Embodiment 11

[0091] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0092] In step A1. the preparation of the emulsifier, the molar mass ratio of the fatty amine A to the sum of polyethylene glycol diglycidyl ether and the epoxy resin is 4:2.5.

[0093] Example 12

[0094] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0095] In step A1. the preparation of the emulsifier, the molar mass ratio of the fatty amine A to the sum of polyethylene glycol diglycidyl ether and the epoxy resin is 4:3.2.

[0096] Embodiment 13

[0097] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0098] In step A1. the preparation of the emulsifier, the molar mass ratio of the fatty amine A to polyethylene glycol diglycidyl ether is 4:1.2.

[0099] Embodiment 14

[0100] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0101] In step A1. the preparation of the emulsifier, the molar mass ratio of the fatty amine A to polyethylene glycol diglycidyl ether is 4:1.5.

[0102] Embodiment 15

[0103] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0104] In step A1. the preparation of the emulsifier, the molar mass ratio of the fatty amine A to polyethylene glycol diglycidyl ether is 4:1.8.

[0105] Example 16

[0106] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0107] In step A1. the preparation of the emulsifier, the molar mass ratio of the fatty amine A to polyethylene glycol diglycidyl ether is 4:2.2.

[0108] Embodiment 17

[0109] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0110] In step A3. the preparation of the curing agent, the mass ratio of the emulsifier to the intermediate is 10:100.

[0111] Embodiment 18

[0112] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0113] In step A3. the preparation of the curing agent, the mass ratio of the emulsifier to the intermediate is 15:100.

[0114] Embodiment 19

[0115] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0116] In step A3. the preparation of the curing agent, the mass ratio of the emulsifier to the intermediate is 30:100.

[0117] Embodiment 20

[0118] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0119] In step A3. the preparation of the curing agent, the mass ratio of the emulsifier to the intermediate is 35:100.

[0120] Embodiment 21

[0121] A curing agent, the preparation method of which is different from that of Example 1 in that:

[0122] In step A3. the preparation of the curing agent, the mass ratio of the emulsifier to the intermediate is 40:100.

[0123] Embodiment 22

[0124] A curing agent, the preparation method of which is different from that of Example 1 in that: in the step A2. preparation of the intermediate, the molar mass ratio of m-xylylenediamine to epoxy resin is 2:0.7.

[0125] Embodiment 23

[0126] A curing agent, the preparation method of which is different from that of Example 1 in that: in the step A2. preparation of the intermediate, the molar mass ratio of m-xylylenediamine to epoxy resin is 2:0.9.

[0127] Embodiment 24

[0128] A curing agent, the preparation method of which is different from that of Example 1 in that: in the step A2. preparation of the intermediate, the molar mass ratio of m-xylylenediamine to epoxy resin is 2:1.4.

[0129] Embodiment 25

[0130] A curing agent, the preparation method of which is different from that of Example 2 in that: in the step A2. preparation of the intermediate, the molar mass ratio of isophorone diamine to epoxy resin is 2:0.7.

[0131] Embodiment 26

[0132] A curing agent, the preparation method of which is different from that of Example 2 in that: in the step A2. preparation of the intermediate, the molar mass ratio of isophorone diamine to epoxy resin is 2:0.9.

[0133] Embodiment 27

[0134] A curing agent, the preparation method of which is different from that of Example 2 in that: in the step A2. preparation of the intermediate, the molar mass ratio of isophorone diamine to epoxy resin is 2:1.4.

[0135] The curing agent prepared in Examples 1-27 was compounded with an epoxy resin paint film, and then various properties of the paint film were measured.

[0136] The preparation method of the paint film is as follows: compound the curing agent with a water-based epoxy resin (model: Guangdong Yinyang Environmental Protection New Material WE-1101), and control the ratio of active hydrogen equivalent to epoxy equivalent in the system to be 1:0.8 during compounding. After compounding, spray with an air spray gun, and the dry film thickness is 50 microns. After drying at room temperature for 7 days, its various properties are measured.

[0137] Among them, the determination of salt spray performance refers to GB / T 1771-2007;

[0138] The determination of activation period refers to CSN 67 3033-1987;

[0139] The glossiness shall be determined according to GB / T 1743-1979;

[0140] The hardness is determined according to GB / T 6739-1996;

[0141] The determination of water resistance refers to GB / T 1733-1993;

[0142] The adhesion test is in accordance with GB / T 9286-1998;

[0143] The determination of flexibility refers to GB / T 4156-1984;

[0144] The test results are as follows:

[0145] Table 1

[0146]

[0147] Table 2

[0148]

[0149]

[0150] Table 3

[0151]

[0152] Table 4

[0153] Embodiment 17 Embodiment 18 Example 1 Embodiment 19 Embodiment 20 Embodiment 21 Emulsifier:Intermediate 10:100 15:100 20:100 30:100 35:100 40:100 Particle size nm (D50) 1000 800 500 150 100 80 Salt spray performance 200h 400h 500h 500h 500h 250h Water resistance 5D 20D 20D 20D 15D 5D

[0154] Table 5

[0155] Embodiment 22 Embodiment 23 Example 1 Embodiment 24 Meta-phenylenediamine:Epoxy resin 2:0.7 2:0.9 2:1.2 2:1.4 Salt spray performance 100h 400h 500h / Active Period 1h 3h 5h / Glossiness 20 40 50 / hardness 2H 2H 2H / Water resistance 5D 20D 20D / Adhesion Level 0 Level 0 Level 0 /

[0156] Table 6

[0157] Embodiment 25 Embodiment 26 Example 2 Embodiment 27 Isophorone diamine: Epoxy resin 2:0.7 2:0.9 2:1.2 2:1.4 Salt spray performance 100h 450h 500h / Active Period 2h 4h 6h / Glossiness 40 60 60 / hardness H 2H 2H / Water resistance 5D 20D 20D / Adhesion Level 3 Level 0 Level 0 /

[0158] As can be seen from Table 1, the comprehensive performance of Example 1 and Example 2 is the best, indicating that the curing agent prepared by using m-phenylenediamine or isophorone diamine can significantly improve the various properties of the paint film after compounding with epoxy resin. In Example 3, although the activation period is the longest, the salt spray performance and water resistance are obviously insufficient. In Example 4 and Example 5, there are defects of too short activation period and insufficient water resistance. In Example 6, the activation period is too short, and its salt spray resistance and water resistance are not good enough. In Example 7, there is a problem of too short activation period.

[0159] As can be seen from Table 2, when the molar mass ratio of the fatty amine A to the sum of polyethylene glycol diglycidyl ether and epoxy resin is 4:2.2 to 4:3, the salt spray performance and water resistance of the epoxy resin paint film obtained are the best. In Example 8, due to the excessive amount of fatty amine A, emulsification cannot be performed and the emulsifier cannot be prepared. In Example 9, although the emulsifier can be prepared, the salt spray performance and water resistance of the paint film have decreased significantly. In Example 12, gel is produced during the preparation of the emulsifier and it cannot be prepared.

[0160] It can be seen from Table 3 that when the molar mass ratio of fatty amine A to polyethylene glycol diglycidyl ether is 4:1.8-4:2, the comprehensive performance of the paint film is the best; when the molar mass ratio of fatty amine A to polyethylene glycol diglycidyl ether is 4:1.5, the salt spray performance and water resistance of the paint film are much lower than those of Example 15 and Example 1. In Example 13, the emulsifier cannot be emulsified during preparation. In Example 16, the emulsifier forms too much gel during preparation, resulting in failure to prepare.

[0161] In Table 4, when the weight ratio of the emulsifier to the intermediate is 10:100, the salt spray performance and water resistance of the paint film are poor, and when the weight ratio of the emulsifier to the intermediate is 40:100, the salt spray performance and water resistance of the paint film also show a significant decrease. When the weight ratio of the emulsifier to the intermediate is 15:100-35:100, the effect is best.

[0162] It can be seen from Table 5 that when the molar mass ratio of m-xylenediamine to epoxy resin is 2:0.9-2:1.2, the comprehensive performance of the paint film is optimal after the prepared curing agent is compounded with the epoxy resin; when the molar mass ratio of m-xylenediamine to epoxy resin is 2:1.4, the intermediate forms a gel during the preparation and cannot be prepared.

[0163] It can be seen from Table 6 that when the molar mass ratio of isophorone diamine to epoxy resin is 2:0.9-2:1.2, the comprehensive performance of the paint film after the prepared curing agent is compounded with the epoxy resin is also the best. When the molar mass ratio of m-phenylenediamine to epoxy resin is 2:1.4, the intermediate also forms a gel during the preparation.

[0164] In order to further verify the technical effect of the present invention, the curing agents of Example 1 and Example 2 were compared with the curing agent of the prior art ( 3986) to compare and measure the properties of the paint film after the curing agent and epoxy resin are compounded. The preparation of the paint film is the same as in the above embodiment, and the corresponding test results are shown in Table VII. In Table VII, the determination of the drying time refers to GB / T1728-1979.

[0165] Table 7

[0166] It can be seen from the results in Table 7 that the hardness, water resistance, flexibility and adhesion performance of the curing agent in the prior art are comparable to those of Example 1 and Example 2.

[0167] In terms of salt spray performance, activation period and drying time tests, Examples 1 and 2 are better than the prior art. 3986 is a commonly used curing agent in the industry, but it needs to be imported from abroad, is expensive, and has unstable supply. The comprehensive performance of the paint film prepared by the curing agent provided by the present invention is not only better than the existing technology, but also has a simpler production process and lower cost.

[0168] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention, and all these changes or substitutions should fall within the protection scope of the claims attached to the present invention.

Claims

1. A curing agent, characterized in that The raw materials for preparation thereof include: an intermediate and an emulsifier, wherein the weight ratio of the emulsifier to the intermediate is (20-30):100; the curing agent is not terminated with a monoepoxy compound; The raw materials for preparing the emulsifier include: fatty amine A, polyethylene glycol diglycidyl ether and epoxy resin; the molar mass ratio of the fatty amine A to the sum of polyethylene glycol diglycidyl ether and epoxy resin is 4:(2.2-3); the molar mass ratio of the fatty amine A to polyethylene glycol diglycidyl is 4:(1.8-2); the epoxy equivalent of the polyethylene glycol diglycidyl ether is 200-1000 g / mol; The raw materials for preparing the intermediate include: fatty amine B and epoxy resin; The fatty amine A is polyetheramine or isophoronediamine; the fatty amine B is meta-xylylenediamine or isophoronediamine; When the fatty amine A is a polyetheramine, the fatty amine B is m-xylylenediamine; When the fatty amine A is isophoronediamine, the fatty amine B is isophoronediamine.

2. The curing agent according to claim 1, characterized in that The molar mass ratio of the fatty amine B to the epoxy resin is 2:(0.9-1.2).

3. A method for preparing a curing agent, characterized in that: The method for preparing the curing agent according to claim 1 or 2 comprises the following steps: mixing the intermediate with the emulsifier, adding water dropwise, and obtaining the curing agent by phase inversion.

4. The method for preparing a curing agent according to claim 3, characterized in that: The preparation method of the emulsifier comprises the following steps: firstly, adding fatty amine A into a reactor, filling with nitrogen, heating to 50-70° C., dropping polyethylene glycol diglycidyl ether, keeping the temperature for 3-5 hours after the dropping is complete, then dropping epoxy resin, keeping the temperature for 3-5 hours after the dropping is complete, and preparing the emulsifier.

5. The method for preparing a curing agent according to claim 3, characterized in that: The preparation method of the intermediate comprises the following steps: firstly, adding fatty amine B into a reactor, filling with nitrogen, heating to 50-70° C., adding a solvent, and then dripping epoxy resin, and after the dripping is completed, keeping the temperature at 50-70° C. for 2 hours to obtain the intermediate.

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