Polyaspartic acid resin modified cashew phenolic aldehyde amine epoxy curing agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of epoxy coatings, in particular to a polyaspartic acid resin modified cashew phenolic aldehyde amine epoxy curing agent as well as a preparation method and application thereof. The preparation method provided by the invention comprises the following steps: mixing first cardanol, first fatty amine, polyaspartic acid ester and an accelerant in an inert atmosphere, adding a first substance for providing a formaldehyde monomer in batches, and carrying out a first Mannich reaction to obtain a first reaction system; and mixing the first reaction system, second cardanol and second aliphatic amine, adding a second substance for providing a formaldehyde monomer in batches, carrying out a second Mannich reaction, dehydrating, adding a double epoxy diluent, and carrying out a ring-opening addition reaction to obtain the polyaspartic acid modified cardanol aldehyde amine epoxy curing agent. The polyaspartic acid resin modified cashew phenolic aldehyde amine epoxy curing agent prepared by the preparation method disclosed by the invention has the advantages of good adhesive force, good corrosion resistance and good water resistance.

Description

Technical Field

[0001] The invention relates to the technical field of epoxy coatings, and in particular to a polyaspartic acid resin modified cardanol aldehyde amine epoxy curing agent, and a preparation method and application thereof. Background Art

[0002] Curing agent is an indispensable component when using epoxy resin. Together with epoxy resin, it determines the performance of the cured product. The most widely used curing agent is aliphatic amine curing agent, such as ethylenediamine, diethylenetriamine and triethylenetetramine. However, low molecular weight aliphatic amine curing agent is easy to absorb moisture in the air under high humidity conditions, and the paint film is easy to turn white and produce orange peel, shrinkage holes and other defects. After curing, the corrosion resistance, water resistance and mechanical strength of the paint film are poor. Summary of the invention

[0003] In view of this, the object of the present invention is to provide a polyaspartic acid resin modified cardanol amine epoxy curing agent and a preparation method and application thereof. The polyaspartic acid resin modified cardanol amine epoxy curing agent prepared by the preparation method of the present invention has good adhesion, good corrosion resistance and water resistance.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a method for preparing a polyaspartic acid resin modified cardanol aldehyde amine epoxy curing agent, comprising the following steps:

[0006] In an inert atmosphere, after mixing the first cardanol, the first fatty amine, the polyaspartic acid ester and the accelerator, adding the first substance providing the formaldehyde monomer in batches, performing a first Mannich reaction, and obtaining a first reaction system;

[0007] The first reaction system, the second cardanol and the second fatty amine are mixed, and the second substance providing formaldehyde monomer is added in batches. After the second Mannich reaction is carried out, dehydration is carried out, and a diepoxy diluent is added to carry out a ring-opening addition reaction to obtain the polyaspartic acid modified cardanol amine epoxy curing agent.

[0008] Preferably, the molar ratio of the first cardanol, the first fatty amine, the polyaspartic acid ester and the formaldehyde monomer in the first substance providing the formaldehyde monomer is (0.4-0.6): (0.2-0.5): (0.2-0.3): (0.5-0.8);

[0009] The first fatty amine includes one or more of N,N-dimethyl-1,3-propylenediamine, N,N-diethyl-1,3-propylenediamine, N,N-dipropyl-1,3-propylenediamine, and N,N-dibutyl-1,3-propylenediamine;

[0010] The model of the polyaspartic acid ester is F420 and / or F520;

[0011] The first substance providing formaldehyde monomer includes paraformaldehyde or a formaldehyde aqueous solution with a mass concentration of 37%.

[0012] Preferably, the mass percentage of the accelerator to the first cardanol is 2-4%;

[0013] The accelerator includes 2,4,6-tris(dimethylaminomethyl)phenol.

[0014] Preferably, the temperature of the first Mannich reaction is 100-110° C., and the time is 3-6 hours.

[0015] Preferably, the molar ratio of the second cardanol, the second fatty amine and the formaldehyde monomer in the second substance providing the formaldehyde monomer is (0.4-0.6): (0.8-1.0): (0.8-1.1);

[0016] The molar ratio of the first cardanol to the second cardanol is (0.4-0.6):(0.4-0.6);

[0017] The second fatty amine includes N'-(3-aminopropyl)-N,N-dimethyl-1,3-propylenediamine;

[0018] The second substance providing formaldehyde monomer includes paraformaldehyde or a formaldehyde aqueous solution with a mass concentration of 37%.

[0019] Preferably, the temperature of the second Mannich reaction is 100-115°C and the time is 3-8h;

[0020] The dehydration temperature is 120° C., the dehydration negative pressure is 3-5 kPa, and the dehydration time is 1 hour.

[0021] Preferably, the diepoxy diluent includes one or more of 1,6-hexanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, ethylene glycol diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, diethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, and triethylene glycol diglycidyl ether;

[0022] The mass of the diepoxy diluent is 2-4% of the total mass of the feed;

[0023] The total mass of the input materials is the total mass of the first cardanol, the first fatty amine, the polyaspartic acid ester, the accelerator, the first substance providing the formaldehyde monomer, the second cardanol, the second fatty amine and the second substance providing the formaldehyde monomer.

[0024] Preferably, the temperature of the ring-opening addition reaction is 70 to 90° C., and the time of the ring-opening addition reaction is 3 to 8 hours.

[0025] The present invention also provides a polyaspartic acid resin modified cardanol aldehyde amine epoxy curing agent prepared by the preparation method described in the above technical scheme.

[0026] The present invention also provides the use of the polyaspartic acid resin modified cardanol aldehyde amine epoxy curing agent described in the above technical solution in the field of epoxy coatings.

[0027] The present invention provides a method for preparing a polyaspartic acid resin modified cashew phenol aldehyde amine epoxy curing agent, comprising the following steps: in an inert atmosphere, after mixing a first cardanol, a first fatty amine, a polyaspartic acid ester and a accelerator, adding a first substance providing a formaldehyde monomer in batches, performing a first Mannich reaction, and obtaining a first reaction system; mixing the first reaction system, a second cardanol and a second fatty amine, adding a second substance providing a formaldehyde monomer in batches, performing a second Mannich reaction, dehydrating, adding a diepoxy diluent, and performing a ring-opening addition reaction to obtain the polyaspartic acid modified cashew phenol aldehyde amine epoxy curing agent. The present invention mainly utilizes the long chain structure containing an ester group in the polyaspartic acid ester to improve the toughness and adhesion performance of the curing agent and the epoxy resin cured product through polyaspartic acid ester modification, and can further improve the salt spray resistance and corrosion resistance of the cured product, thereby broadening the application scenarios of the cashew phenol aldehyde amine epoxy curing agent; in particular, it is suitable for application scenarios with high requirements for salt spray resistance and adhesion performance. When the curing agent prepared by the preparation method of the present invention is matched with epoxy resin, the curing agent has excellent comprehensive physical properties, good flexibility, fast curing speed, excellent impact resistance, good salt spray resistance, high hardness, and can be industrially produced; when the curing agent prepared by the preparation method of the present invention is matched with a homemade epoxy resin (application example) color paint, the impact resistance can reach more than 80kg·cm without cracking in both positive and negative impacts, the flexibility is 1mm, the hardness can reach H level, the cross-cut test is level 0, and the pull-out adhesion reaches more than 13MPa. DETAILED DESCRIPTION

[0028] The present invention provides a method for preparing a polyaspartic acid resin modified cardanol aldehyde amine epoxy curing agent, comprising the following steps:

[0029] In an inert atmosphere, after mixing the first cardanol, the first fatty amine, the polyaspartic acid ester and the accelerator, adding the first substance providing the formaldehyde monomer in batches, performing a first Mannich reaction, and obtaining a first reaction system;

[0030] The first reaction system, the second cardanol and the second fatty amine are mixed, and the second substance providing formaldehyde monomer is added in batches. After the second Mannich reaction is carried out, dehydration is carried out, and a diepoxy diluent is added to carry out a ring-opening addition reaction to obtain the polyaspartic acid modified cardanol amine epoxy curing agent.

[0031] In the present invention, unless otherwise specified, all preparation raw materials are commercially available products well known to those skilled in the art.

[0032] The present invention mixes the first cardanol, the first fatty amine, the polyaspartic acid ester and the accelerator in an inert atmosphere, and then adds the first substance providing the formaldehyde monomer in batches to carry out the first Mannich reaction to obtain the first reaction system.

[0033] In the present invention, the inert atmosphere is preferably N2 atmosphere.

[0034] In the present invention, the purity of the first cardanol is preferably ≥90%.

[0035] In the present invention, the first fatty amine preferably includes one or more of N,N-dimethyl-1,3-propylenediamine, N,N-diethyl-1,3-propylenediamine, N,N-dipropyl-1,3-propylenediamine, and N,N-dibutyl-1,3-propylenediamine. When the first fatty amine is two or more of the above specific selections, the present invention does not have any special restrictions on the ratio of the above specific substances, and they can be mixed in any ratio. In an embodiment of the present invention, the first fatty amine can be N,N-dimethyl-1,3-propylenediamine or N,N-diethyl-1,3-propylenediamine.

[0036] In the present invention, the polyaspartic acid ester is preferably F420 and / or F520. When the polyaspartic acid ester is F420 and F520, the present invention has no special limitation on the ratio of F420 and F520, and they can be mixed in any ratio. In an embodiment of the present invention, the polyaspartic acid ester can be F420 or F520.

[0037] In the present invention, the accelerator preferably includes 2,4,6-tris(dimethylaminomethyl)phenol.

[0038] In the present invention, the first substance providing formaldehyde monomer preferably includes paraformaldehyde or a formaldehyde aqueous solution with a mass concentration of 37%.

[0039] In the present invention, the molar ratio of the first cardanol, the first fatty amine, the polyaspartic acid ester and the first substance providing formaldehyde monomers is preferably (0.4-0.6): (0.2-0.5): (0.2-0.3): (0.5-0.8), and more preferably (0.45-0.55): (0.3-0.4): (0.24-0.26): (0.6-0.7). In an embodiment of the present invention, the molar ratio of the first cardanol, the first fatty amine, the polyaspartic acid ester and the first substance providing formaldehyde monomers may be 0.4:0.25:0.2:0.5, 0.6:0.5:0.2:0.8, 0.4:0.2:0.3:0.6 or 0.5:0.4:0.3:0.8.

[0040] In the present invention, the mass percentage of the accelerator to the first cardanol is preferably 2-4%, more preferably 2.5-3.5%, and most preferably 2.8-3.2%. In an embodiment of the present invention, the mass percentage of the accelerator to the first cardanol may be 4%, 2% or 3%.

[0041] The present invention does not have any special limitation on the mixing process, and the mixing process may be carried out using a process well known to those skilled in the art.

[0042] In the present invention, the first substance providing formaldehyde monomer is preferably added in 4 to 6 batches. The temperature for adding the first substance providing formaldehyde monomer in batches is preferably 70 to 80° C., more preferably 73 to 78° C. In an embodiment of the present invention, the addition temperature of the first substance providing formaldehyde monomer may be 71° C., 73° C., 74° C. or 75° C. The first substance providing formaldehyde monomer may be added in 4 batches or in 6 batches.

[0043] In the present invention, the temperature of the first Mannich reaction is preferably 100-110° C., more preferably 103-106° C.; the time is preferably 3-6 h, more preferably 4-5 h.

[0044] After obtaining the first reaction system, the present invention mixes the first reaction system, the second cardanol and the second fatty amine, adds the second substance providing formaldehyde monomer in batches, performs a second Mannich reaction, dehydrates, adds a diepoxy diluent, performs a ring-opening addition reaction, and obtains the polyaspartic acid modified cardanol aldehyde amine epoxy curing agent.

[0045] In the present invention, the purity of the second cardanol is preferably ≥ 90%.

[0046] In the present invention, the second fatty amine preferably includes N'-(3-aminopropyl)-N,N-dimethyl-1,3-propylenediamine; the second substance providing formaldehyde monomer preferably includes paraformaldehyde or a formaldehyde aqueous solution with a mass concentration of 37%.

[0047] In the present invention, the molar ratio of the second cardanol, the second fatty amine and the second substance providing formaldehyde monomer is preferably (0.4-0.6): (0.8-1.0): (0.8-1.1), more preferably (0.45-0.55): (0.85-0.95): (0.9-1.0); the molar ratio of the first cardanol and the second cardanol is preferably (0.4-0.6): (0.4-0.6), more preferably (0.45-0.55): (0.45-0.55). In an embodiment of the present invention, the molar ratio of the second cardanol, the second fatty amine and the second substance providing formaldehyde monomer can be 0.6:1:1.1, 0.4:0.8:0.8, 0.6:1:1 or 0.5:0.9:0.8; the molar ratio of the first cardanol and the second cardanol can be 0.4:0.6, 0.6:0.4 or 0.5:0.5.

[0048] The present invention does not have any special limitation on the mixing process, and the mixing process may be carried out using a process well known to those skilled in the art.

[0049] In the present invention, the second substance providing formaldehyde monomer is preferably added in 4 to 6 batches, and the addition temperature of the second substance providing formaldehyde monomer is preferably 70 to 80° C., more preferably 73 to 78° C. In an embodiment of the present invention, the addition temperature of the second substance providing formaldehyde monomer may be 71° C., 73° C., 74° C. or 75° C. The second substance providing formaldehyde monomer may be added in 4 batches or in 6 batches.

[0050] In the present invention, the temperature of the second Mannich reaction is preferably 100-115°C, more preferably 105-110°C; the time is preferably 3-8h, more preferably 4-6h. In an embodiment of the present invention, the temperature of the second Mannich reaction can be 100°C, 115°C, and the time can be 8h, 6h, 5h or 4h.

[0051] In the present invention, the dehydration temperature is preferably 120° C., the dehydration negative pressure is preferably 3 to 5 kPa, and the dehydration time is preferably 1 hour.

[0052] In the present invention, the diepoxy diluent preferably includes one or more of 1,6-hexanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, ethylene glycol diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, diethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, and triethylene glycol diglycidyl ether. When the diepoxy diluent is two or more of the above-mentioned specific selections, the present invention does not have any special restrictions on the ratio of the above-mentioned specific substances, and can be mixed in any ratio. In an embodiment of the present invention, the diepoxy diluent can be 1,6-hexanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, or diethylene glycol diglycidyl ether.

[0053] In the present invention, the mass of the diepoxy diluent is preferably 2-4% of the total mass of the feed, and more preferably 2.5-3.5%. In an embodiment of the present invention, the mass of the diepoxy diluent can be 2%, 3% or 4% of the total mass of the feed. In the present invention, the total mass of the feed is preferably the total mass of the first cardanol, the first fatty amine, the polyaspartic acid ester, the accelerator, the first substance providing formaldehyde monomers, the second cardanol, the second fatty amine and the second substance providing formaldehyde monomers.

[0054] In the present invention, the temperature for adding the diepoxy diluent is preferably 70-90° C., more preferably 75-85° C. In an embodiment of the present invention, the temperature for adding the diepoxy diluent may be 70° C., 75° C., 80° C. or 90° C.

[0055] In the present invention, the temperature of the ring-opening addition reaction is preferably 70 to 90°C, more preferably 75 to 85°C; the time of the ring-opening addition reaction is preferably 3 to 8 hours, more preferably 4 to 6 hours. In an embodiment of the present invention, the temperature of the ring-opening addition reaction can be 70°C, 90°C, 80°C or 75°C; the time can be 8 hours, 3 hours, 5 hours or 7 hours.

[0056] The present invention also provides a polyaspartic acid resin modified cardanol aldehyde amine epoxy curing agent prepared by the preparation method described in the above technical scheme.

[0057] The present invention also provides the application of the polyaspartic acid resin modified cardanol aldehyde amine epoxy curing agent in the field of epoxy coatings. The present invention does not have any special limitation on the method of the application, and the method well known to those skilled in the art can be used.

[0058] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] Example 1

[0060] In an inert gas atmosphere (inert gas is N2), 120g (0.4mol) of cardanol (purity is 92%), 32.5g (0.25mol) of N,N-diethyl-1,3-propylenediamine, 116.4g (0.2mol) of polyaspartic acid ester F520 and 4.8g (0.018mol) of 2,4,6-tris (dimethylaminomethyl) phenol were put into a reaction kettle, and 15g (formaldehyde monomer) was added in 4 batches at a temperature of 71°C. : 0.5mol) of paraformaldehyde, heated to 100°C for reaction for 5h; cooled to below 80°C, added 180g (0.6mol) of cardanol and 159g (1mol) of N'-(3-aminopropyl)-N,N-dimethyl-1,3-propylenediamine and mixed evenly, added 33g (1.1mol) of paraformaldehyde in 6 batches at 71°C, heated to 100°C for reaction for 8 hours, and after the reaction was completed, heated to 120°C and dehydrated at a negative pressure of 3KPa for 1 hour;

[0061] The temperature was lowered to 70° C., 26.24 g (4%) of 1,6-hexanediol diglycidyl ether was added, and the mixture was kept at 70° C. for reaction for 8 hours to obtain a modified cashew phenol aldehyde amine curing agent.

[0062] Example 2

[0063] In an inert gas atmosphere (inert gas is N2), 180g (0.6mol) of cardanol (purity is 92%), 51g (0.5mol) of N,N-dimethyl-1,3-propylenediamine, 116.4g (0.2mol) of polyaspartic acid ester F520 and 3.6g (0.014mol) of 2,4,6-tris (dimethylaminomethyl) phenol were put into a reaction kettle, and 64.86g (0.8mol) of a 37% formaldehyde aqueous solution was added in 6 batches at a temperature of 73°C, and the temperature was raised to 110°C for reaction for 6h;

[0064] Cool down to below 80°C, add 120g (0.4mol) of cardanol (purity 92%) and 127.2g (0.8mol) of N'-(3-aminopropyl)-N,N-dimethyl-1,3-propylenediamine, mix well, add 64.86g (0.8mol) of 37% formaldehyde aqueous solution in 4 batches at 73°C, heat to 115°C for 6h, and after the reaction is completed, heat to 120°C and dehydrate at a negative pressure of 5KPa for 1h;

[0065] The temperature was lowered to 90°C, 19.28 g (3%) of 1,4-butanediol diglycidyl ether was added, and the mixture was kept at 90°C for 3 h to obtain a modified cashew phenol aldehyde amine curing agent.

[0066] Example 3

[0067] In an inert gas atmosphere (inert gas is N2), 120g (0.4mol) of cardanol, 20.4g (0.2mol) of N,N-dimethyl-1,3-propylenediamine, 166.2g (0.3mol) of polyaspartic acid ester F420 and 4.8g (0.018mol) of 2,4,6-tris (dimethylaminomethyl) phenol were put into a reaction kettle, and 18g (formaldehyde monomer: 0.6mol) of polyformaldehyde was added in 4 batches at 74°C, and the temperature was raised to 110°C for reaction for 3h;

[0068] Cool down to below 80°C, add 180g (0.6mol) of cardanol and 159g (1mol) of N'-(3-aminopropyl)-N,N-dimethyl-1,3-propylenediamine, mix well, add 30g (1mol) of paraformaldehyde in 6 batches at 74°C, heat to 110°C and react for 5h. After the reaction is completed, heat to 120°C and dehydrate at a negative pressure of 4KPa for 1h;

[0069] The temperature was lowered to 80° C., 13.87 g (2%) of diethylene glycol diglycidyl ether was added, and the mixture was kept at 80° C. for 5 h to obtain a modified cashew phenol aldehyde amine curing agent.

[0070] Example 4

[0071] In an inert gas atmosphere (inert gas is N2), 150g (0.5mol) of cardanol (purity is 92%), 52g (0.4mol) of N,N-diethyl-1,3-propylenediamine, 166.2g (0.3mol) of polyaspartic acid ester F420 and 4.5g (0.017mol) of 2,4,6-tris (dimethylaminomethyl) phenol were put into a reaction kettle, and 24g (0.8mol) of polyformaldehyde was added in 5 batches at 75°C, and the temperature was raised to 105°C for reaction for 4h;

[0072] Cool down to below 80°C, add 150g (0.5mol) of cardanol (purity 92%) and 143.1g (0.9mol) of N'-(3-aminopropyl)-N,N-dimethyl-1,3-propylenediamine, mix well, add 24g (formaldehyde monomer: 0.8mol) of paraformaldehyde in 6 batches at 75°C, heat to 115°C and react for 4h. After the reaction is completed, heat to 120°C and dehydrate at a negative pressure of 3KPa for 1h;

[0073] The temperature was lowered to 75°C, 14.19 g (2%) 1,4-butanediol diglycidyl ether was added, and the mixture was kept at 75°C for 7 h to obtain a modified cashew phenol aldehyde amine curing agent.

[0074] Comparative Example 1

[0075] Reference Example 1, except that polyaspartic acid ester was not added: under an inert gas atmosphere (inert gas is N2), 120g (0.4mol) of cardanol (purity is 92%), 32.5g (0.25mol) of N,N-diethyl-1,3-propylenediamine and 4.8g (0.018mol) of 2,4,6-tris (dimethylaminomethyl) phenol were put into a reaction kettle, 15g (0.5mol) of paraformaldehyde was added in 4 batches at a temperature of 71°C, and the temperature was raised to 100°C for reaction for 5h;

[0076] Cool down to below 80°C, add 180g (0.6mol) of cardanol (purity 92%) and 159g (1mol) of N'-(3-aminopropyl)-N,N-dimethyl-1,3-propylenediamine, mix well, add 33g (formaldehyde monomer: 1.1mol) of paraformaldehyde in 6 batches at 71°C, heat to 100°C and react for 8h. After the reaction is completed, heat to 120°C and dehydrate at a negative pressure of 3KPa for 1h;

[0077] The temperature was lowered to 70°C, 21.58 g (4%) of 1,6-hexanediol diglycidyl ether was added, and the mixture was kept at 70°C for 8 h to obtain a modified cashew phenol aldehyde amine curing agent.

[0078] Comparative Example 2

[0079] Reference Example 2, except that polyaspartic acid ester was not added: under an inert gas atmosphere (inert gas is N2), 180g (0.6mol) of cardanol (purity is 92%), 51g (0.5mol) of N,N-dimethyl-1,3-propylenediamine and 3.6g (0.014mol) of 2,4,6-tris (dimethylaminomethyl) phenol were put into a reaction kettle, and 64.86g (0.8mol) of a 37% formaldehyde aqueous solution was added in 6 batches at a temperature of 73°C, and the temperature was raised to 110°C for reaction for 6h;

[0080] Cool down to below 80°C, add 120g (0.4mol) of cardanol (purity 92%) and 127.2g (0.8mol) of N'-(3-aminopropyl)-N,N-dimethyl-1,3-propylenediamine, mix well, add 64.86g (0.8mol) of 37% formaldehyde aqueous solution in 4 batches at 73°C, heat to 115°C for 6h, and after the reaction is completed, heat to 120°C and dehydrate at a negative pressure of 5KPa for 1h;

[0081] The temperature was lowered to 90° C., 15.79 g (3%) of 1,4-butanediol diglycidyl ether was added, and the mixture was kept at 90° C. for reaction for 3 h to obtain a modified cashew phenol aldehyde amine curing agent.

[0082] Comparative Example 3

[0083] Reference Example 3, except that polyaspartic acid ester was not added: under an inert gas atmosphere (the inert gas was N2), 120 g (0.4 mol) of cardanol (purity was 92%), 20.4 g (0.2 mol) of N,N-dimethyl-1,3-propylenediamine and 4.8 g (0.018 mol) of 2,4,6-tris (dimethylaminomethyl) phenol were put into a reaction kettle, 18 g (formaldehyde monomer: 0.6 mol) of paraformaldehyde was added in 4 batches at 74°C, and the temperature was raised to 110°C for reaction for 3 hours;

[0084] Cool down to below 80°C, add 180g (0.6mol) of cardanol (purity 92%) and 159g (1mol) of N'-(3-aminopropyl)-N,N-dimethyl-1,3-propylenediamine, mix well, add 30g (1mol) of paraformaldehyde in 6 batches at 74°C, heat to 110°C and react for 5h. After the reaction is completed, heat to 120°C and dehydrate at a negative pressure of 4KPa for 1h;

[0085] The temperature was lowered to 80° C., 10.55 g (2%) of diethylene glycol diglycidyl ether was added, and the mixture was kept at 80° C. for 5 h to obtain a modified cashew phenol aldehyde amine curing agent.

[0086] Comparative Example 4

[0087] Reference Example 4, except that polyaspartic acid ester was not added: under an inert gas atmosphere (the inert gas was N2), 150 g (0.5 mol) of cardanol (purity was 92%), 52 g (0.4 mol) of N,N-diethyl-1,3-propylenediamine and 4.5 g (0.017 mol) of 2,4,6-tris(dimethylaminomethyl)phenol were put into a reaction kettle, and 24 g (formaldehyde monomer: 0.8 mol) of paraformaldehyde was added in 5 batches at 75°C, and the temperature was raised to 105°C for reaction for 4 hours;

[0088] Cool down to below 80°C, add 150g (0.5mol) of cardanol and 143.1g (0.9mol) of N'-(3-aminopropyl)-N,N-dimethyl-1,3-propylenediamine, mix well, add 24g (0.8mol) of paraformaldehyde in 6 batches at 75°C, heat to 115°C and react for 4h. After the reaction is completed, heat to 120°C and dehydrate at a negative pressure of 3KPa for 1h;

[0089] The temperature was lowered to 75° C., 10.86 g (2%) of 1,4-butanediol diglycidyl ether was added, and the mixture was kept at 75° C. for 7 h to obtain a modified cashew phenol aldehyde amine curing agent.

[0090] Comparative Example 5

[0091] Commercially available cashew phenol aldehyde amine curing agent: active hydrogen equivalent 190g / eq.

[0092] Application Examples

[0093] Homemade epoxy resin: including component A and component B;

[0094] The composition of component A is shown in Table 1:

[0095] Table 1A Component ratio

[0096]

[0097] The modified cashew phenol aldehyde amine curing agent prepared in Examples 1 to 4 and Comparative Examples 1 to 4 and the commercially available active hydrogen equivalent 190 g / eq cashew phenol aldehyde amine curing agent described in Comparative Example 5 were used as component B, and mixed with the above-mentioned component A according to the active hydrogen equivalent: epoxy equivalent = 1: 1, and 15% of the total mass of a xylene n-butanol mixed solution (xylene: n-butanol = 3: 1) was added for dilution, and the epoxy coating was obtained after stirring evenly. The epoxy coating was evenly sprayed onto the tinplate by air spraying, and the paint film performance test was performed after drying according to the test standard requirements. The test results are shown in Tables 2 to 3:

[0098] Table 2 Performance of paint films prepared by modified cardanol aldehyde amine curing agent prepared by Examples 1 to 4

[0099]

[0100] Table 3 Performance of the paint films prepared by the modified phenol aldehyde amine curing agent prepared by Comparative Examples 1 to 4 and the commercially available phenol aldehyde amine curing agent with an active hydrogen equivalent of 190 g / eq described in Comparative Example 5

[0101]

[0102] It can be seen from Tables 2 to 3 that after being used in combination with the homemade epoxy resin E51 paint, with tinplate as the test substrate, the polyaspartic acid ester resin modified cashew phenol aldehyde amine epoxy curing agent provided by the present invention has a 1000h salt spray corrosion resistance width of less than 1.0cm, a pull-out adhesion of more than 13MPa, a flexibility of 1mm, an impact resistance of more than 80kg.cm, and a cross-cut adhesion of 0 level; while the cashew phenol aldehyde amine curing agent not modified by the polyaspartic acid ester resin has a 1000h salt spray corrosion resistance width of more than 1.05cm, a pull-out adhesion of less than 13MPa, a flexibility of 1mm, an impact resistance of less than 70kg.cm, and a cross-cut adhesion of up to 2 levels; in summary, the polyaspartic acid ester resin modified cashew phenol aldehyde amine epoxy curing agent provided by the present invention has excellent salt spray corrosion resistance, good mechanical properties such as adhesion, impact resistance, and flexibility, and can be applied to fields with higher requirements for salt spray resistance and mechanical properties.

[0103] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a polyaspartic acid resin modified cardanol aldehyde amine epoxy curing agent, characterized in that: The following steps are involved: In an inert atmosphere, after mixing the first cardanol, the first fatty amine, the polyaspartic acid ester and the accelerator, adding the first substance providing the formaldehyde monomer in batches, performing a first Mannich reaction, and obtaining a first reaction system; The first reaction system, the second cardanol and the second fatty amine are mixed, and the second substance providing formaldehyde monomer is added in batches. After the second Mannich reaction is carried out, dehydration is carried out, and a diepoxy diluent is added to carry out a ring-opening addition reaction to obtain the polyaspartic acid modified cardanol amine epoxy curing agent.

2. The preparation method according to claim 1, characterized in that The molar ratio of the first cardanol, the first fatty amine, the polyaspartic acid ester and the formaldehyde monomer in the first substance providing the formaldehyde monomer is (0.4-0.6): (0.2-0.5): (0.2-0.3): (0.5-0.8); The first fatty amine includes one or more of N,N-dimethyl-1,3-propylenediamine, N,N-diethyl-1,3-propylenediamine, N,N-dipropyl-1,3-propylenediamine, and N,N-dibutyl-1,3-propylenediamine; The model of the polyaspartic acid ester is F420 and / or F520; The first substance providing formaldehyde monomer includes paraformaldehyde or a formaldehyde aqueous solution with a mass concentration of 37%.

3. The preparation method according to claim 1, characterized in that: The mass percentage of the accelerator to the first cardanol is 2-4%; The accelerator includes 2,4,6-tris(dimethylaminomethyl)phenol.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The temperature of the first Mannich reaction is 100-110° C., and the time is 3-6 hours.

5. The preparation method according to claim 1, characterized in that: The molar ratio of the second cardanol, the second fatty amine and the formaldehyde monomer in the second substance providing the formaldehyde monomer is (0.4-0.6): (0.8-1.0): (0.8-1.1); The molar ratio of the first cardanol to the second cardanol is (0.4-0.6):(0.4-0.6); The second fatty amine includes N'-(3-aminopropyl)-N,N-dimethyl-1,3-propylenediamine; The second substance providing formaldehyde monomer includes paraformaldehyde or a formaldehyde aqueous solution with a mass concentration of 37%.

6. The preparation method according to claim 1 or 5, characterized in that: The temperature of the second Mannich reaction is 100-115°C and the time is 3-8h; The dehydration temperature is 120° C., the dehydration negative pressure is 3-5 kPa, and the dehydration time is 1 hour.

7. The preparation method according to claim 1, characterized in that: The diepoxy diluent includes one or more of 1,6-hexanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, ethylene glycol diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, diethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, and triethylene glycol diglycidyl ether; The mass of the diepoxy diluent is 2-4% of the total mass of the feed; The total mass of the input materials is the total mass of the first cardanol, the first fatty amine, the polyaspartic acid ester, the accelerator, the first substance providing the formaldehyde monomer, the second cardanol, the second fatty amine and the second substance providing the formaldehyde monomer.

8. The preparation method according to claim 1, characterized in that: The temperature of the ring-opening addition reaction is 70 to 90° C., and the time of the ring-opening addition reaction is 3 to 8 hours.

9. The polyaspartic acid resin modified cardanol aldehyde amine epoxy curing agent prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the polyaspartic acid resin modified cardanol aldehyde amine epoxy curing agent according to claim 9 in the field of epoxy coatings.

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