Water-based modified polyamine curing agent with high salt spray resistance and preparation method thereof

Abstract

The invention discloses a water-based modified polyamine curing agent and a preparation method thereof. The water-based modified polyamine curing agent comprises 10-38 parts of polybasic organic amine, 1-12 parts of polybasic organic acid, 1-12 parts of unit organic acid, 1-30 parts of an emulsifier, 1-25 parts of epoxy resin, 0-35 parts of an epoxy diluent, 0-22 parts of an alcohol ether solvent, 0-60 parts of deionized water and 0-5 parts of an antioxidant. The water-based modified polyamine curing agent is uniform, fine, good in salt mist resistance, quick to dry, good in adhesive force, good in impact resistance, good in flexibility, good in water resistance, low in cost and the like, and is mainly applied to the fields of containers, rail transit, steel structures and the like.

Description

Technical Field

[0001] The invention relates to a water-based modified polyamine curing agent and a preparation method thereof, and belongs to the field of water-based epoxy curing agents. Background Art

[0002] Epoxy resin coatings are widely used in the field of metal anti-corrosion coatings because of their excellent physical and chemical properties and their ability to stably adhere to a variety of metal substrates. Traditional two-component epoxy coatings have high VOCs and cause serious environmental pollution. Waterborne epoxy coatings can significantly reduce volatile organic compound emissions by replacing solvent-based epoxy coatings, which is beneficial to environmental protection. Therefore, water-based two-component epoxy coatings are the development trend of epoxy coatings today. Among them, water-based amine curing agent is an important component.

[0003] Chinese patent publication number CN117777408A discloses an alicyclic amine nonionic water-based epoxy curing agent and a preparation method thereof, comprising the following preparation steps: (1) addition and chain extension reaction: dripping a mixture of bisphenol A epoxy resin and polyether diglycidyl ether into the alicyclic amine to carry out addition and chain extension reaction; (2) dripping a monoepoxy compound into the previous reaction solution to carry out end-capping reaction; (3) after the end-capping reaction is completed, adding deionized water to the reaction solution for dispersion, and obtaining a water-based alicyclic amine epoxy curing agent after uniform dispersion.

[0004] Chinese Patent Publication No. CN109608622A discloses a method for preparing a nonionic water-based polyamide curing agent, which is characterized by comprising the following steps: (1) Preparation of polyamic acid intermediate a: low molecular weight polyether amine and unsaturated acid anhydride are put into a reaction device, slowly heated to 80-100°C under nitrogen protection, stirring, condensation and water separation and reflux conditions, and kept warm for reaction for 1-2 hours to obtain unsaturated polyamic acid intermediate a; (2) addition of intermediate a and polyamine: polyamine is slowly added dropwise to the above unsaturated polyamic acid intermediate a to carry out Michael addition reaction, the dropping time is 1-2 hours, and the heat preservation reaction time is 1-2 hours. The reaction temperature is controlled at 100-120°C to obtain a polyamic acid-polyamine adduct intermediate b; (3) polyamidation reaction: an excess amount of polyamine is subjected to amidation reaction with the intermediate b at 180-200°C under reflux conditions for 2-3 hours, and then the temperature is continuously raised to 200-220°C for 2-3 hours until all water is evaporated, thereby obtaining a copolymer of the intermediate b and the polyamine, a polyamide curing agent; (4) water dispersion: deionized water is slowly added dropwise to the polyamide curing agent at 60±5°C with high-speed stirring for about 30 minutes to obtain a solid content of 50-60wt%, thereby obtaining a non-ionic water-based polyamide curing agent.

[0005] However, the current water-based amine curing agents' salt spray resistance, quick drying, acid and alkali resistance, impact resistance, flexibility, water resistance, low cost, and compatibility with zinc powder are all areas that require continued in-depth research. Summary of the invention

[0006] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, the present invention provides a water-based modified polyamine curing agent, which has good salt spray resistance, fast drying, good impact resistance, good flexibility, good water resistance, low cost, good compatibility with zinc powder, and is environmentally friendly.

[0007] The present invention also provides a method for preparing the above-mentioned water-based modified polyamine curing agent, and the preparation method is as follows:

[0008] A water-based modified polyamine curing agent, characterized in that it comprises the following components in parts by weight:

[0009] Polybasic organic amine: 10-38 parts, polybasic organic acid: 0-12 parts, monobasic organic acid: 0-12 parts, emulsifier: 0-30 parts, epoxy resin: 0-25 parts, epoxy diluent: 0-35 parts, alcohol ether solvent: 0-22 parts, deionized water 0-60 parts, antioxidant: 0-5 parts.

[0010] As a preferred embodiment, the above-mentioned water-based modified polyamine curing agent, the polyamine organic amine includes at least one of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, meta-xylylenediamine and isophoronediamine.

[0011] As a preferred embodiment, in the above-mentioned water-based modified polyamine curing agent, the polybasic organic acid includes at least one of dimer acid, trimer acid, sebacic acid, azelaic acid, suberic acid and citric acid.

[0012] As a preferred embodiment, in the above-mentioned water-based modified polyamine curing agent, the organic acid unit includes at least one of soybean oleic acid, linoleic acid and tall oil acid.

[0013] As a preferred embodiment, the above-mentioned water-based modified polyamine curing agent, the emulsifier includes polyethylene oxide glycidyl ether, the molecular weight of which is 500-15000, and the emulsifier can be a high molecular substance obtained by chemical reaction with epoxy resin.

[0014] As a preferred embodiment, the above-mentioned water-based modified polyamine curing agent, the epoxy resin includes at least one of liquid or solid bisphenol A epoxy resin, bisphenol F epoxy resin, and novolac epoxy resin.

[0015] As a preferred embodiment, the water-based modified polyamine curing agent and the epoxy diluent described above include at least one of butyl glycidyl ether, C12-14 alcohol glycidyl ether, C8-10 alcohol glycidyl ether, butylphenyl glycidyl ether, cardanol glycidyl ether, trimethylolpropane polyglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, polypropylene glycol diglycidyl ether, tertiary carbonic acid glycidyl ether, phenyl glycidyl ether, o-cresol glycidyl ether, nonylphenol glycidyl ether, and benzyl glycidyl ether.

[0016] As a preferred embodiment, in the above-mentioned water-based modified polyamine curing agent, the alcohol ether solvent includes at least one of propylene glycol monomethyl ether, ethylene glycol monobutyl ether, dipropylene glycol butyl ether and dipropylene glycol methyl ether.

[0017] As a preferred embodiment, the water-based modified polyamine curing agent and the antioxidant include at least one of tert-butyl hydroxyanisole, dibutyl hydroxytoluene, tert-butyl hydroquinone and antioxidant 1010.

[0018] The method for modifying a water-based polyamine curing agent provided by the present invention comprises the following steps:

[0019] S1: reacting polyamine, polybasic organic acid and monobasic organic acid according to the ratio at 120 to 220° C. for 0.5 to 2 hours to perform epoxy ring-opening reaction to obtain prepolymer 1;

[0020] S2: adding epoxy resin to prepolymer 1, reacting at 80-120° C. for 0.5-2 hours to obtain prepolymer 2;

[0021] S3: adding an emulsifier to prepolymer 2, reacting at 85-140° C. for 3-6 hours to obtain prepolymer 3;

[0022] S4: adding epoxy diluent to prepolymer 3, reacting at 40-70° C. for 2-4 hours to obtain prepolymer 4;

[0023] S5: Add antioxidant, alcohol ether solvent and deionized water to prepolymer 4 as needed and stir evenly to obtain a water-based modified polyamine curing agent.

[0024] According to the above preparation method, the water-based modified polyamine curing agent is used in water-based epoxy zinc-rich coating.

[0025] According to the above preparation method, the water-based modified polyamine curing agent is used in water-based metal anti-corrosion coatings.

[0026] Compared with the prior art, the present invention has the following outstanding advantages:

[0027] (1) The water-based modified polyamine curing agent prepared by the present invention uses polyamine, polyacid, and monoacid to dehydrate under high temperature conditions to form a polyamide-amide molecular structure to obtain a prepolymer 1, which can increase the flexibility, impact resistance, water resistance, oil resistance, etc. of the two-component epoxy system.

[0028] (2) Prepolymer 1 and epoxy resin are further subjected to chain extension reaction to obtain prepolymer 2, which can increase the molecular weight and improve the compatibility of the curing agent with the water-based epoxy emulsion, thereby improving the mechanical properties, chemical resistance, adhesion, electrical properties, etc. of the water-based two-component epoxy coating.

[0029] (3) Prepolymer 2 and the emulsifier further react to obtain prepolymer 3, which mainly increases the hydrophilicity of the curing agent and gives the curing agent water emulsification properties and anti-hydrolysis properties.

[0030] (4) Prepolymer 3 and epoxy reactive diluent undergo a ring-opening reaction to improve physical and mechanical properties, chemical resistance, and salt spray resistance.

[0031] (5) A high molecular polymer with a special structure is synthesized through multi-step chemical reactions. The curing agent contains a specific polyamide-amide-based polyamine chain segment, a polyether chain segment, an alicyclic ring or a benzene ring structure, so it has excellent salt spray resistance, water resistance, and oil resistance, and can be used in the field of heavy-duty anti-corrosion coatings.

[0032] (6) The water-based modified polyamine curing agent prepared by the present invention has excellent flexibility and good wettability to zinc powder by optimizing the ratio of rigid structure to flexible structure.

[0033] (7) The water-based modified polyamine curing agent prepared by the method is environmentally friendly and low-cost.

[0034] (8) The organic water-based modified polyamine curing agent prepared by the present invention does not contain any organic acid and has a wide selectivity for pigments, fillers, additives and substrates, thus expanding the application field of water-based two-component epoxy coatings. DETAILED DESCRIPTION

[0035] The following are specific embodiments of the present invention, and the technical solutions of the present invention are further described with reference to the embodiments, but the present invention is not limited to these embodiments.

[0036] Example 1

[0037] The specific process of preparing a water-based modified polyamine curing agent is as follows:

[0038] First, 185 kg of dimer acid, 50 kg of tall oil acid, 80 kg of isophorone diamine and 80 kg of ethylenediamine were reacted at 200 ° C for 4 hours. Then, they were reacted with 64 kg of epoxy resin (trade name E51) at 100 ° C for 1 hour. The obtained reactant was reacted with 322 kg of emulsifier (polyethylene glycol glycidyl ether, molecular weight: 1750) at 120 ° C for 2 hours, and then with 216 kg of benzyl glycidyl ether for chain extension reaction, cooled to 60 ° C, and 247 kg of water was added for 1 hour to obtain a water-based modified polyamine curing agent.

[0039] After testing, the water-based modified polyamine curing agent prepared in this embodiment:

[0040] Solid content (%): 79.8

[0041] Viscosity (25℃)cps:15000

[0042] Active hydrogen equivalent (g / mol): 150

[0043] Amine value (mgKOH / g): 210.

[0044] Example 2

[0045] The specific process of preparing a water-based modified polyamine curing agent is as follows:

[0046] First, 185 kg of dimer acid, 50 kg of soybean oleic acid, 74 kg of meta-xylylenediamine and 77 kg of ethylenediamine were reacted at 200 ° C for 4 hours. Then, they were reacted with 64 kg of epoxy resin (trade name E51) at 100 ° C for 1 hour. The obtained reactant was then reacted with 322 kg of emulsifier (polyethylene glycol glycidyl ether, molecular weight: 1750) at 120 ° C for 2 hours, and then with 195 kg of butyl glycidyl ether for chain extension reaction, cooled to 60 ° C, and 240 kg of water was added for 1 hour to obtain a water-based modified polyamine curing agent.

[0047] After testing, the water-based modified polyamine curing agent prepared in this embodiment:

[0048] Solid content (%): 78.9

[0049] Viscosity (25℃)cps:20000

[0050] Active hydrogen equivalent (g / mol): 150

[0051] Amine value (mgKOH / g): 209

[0052] Example 3

[0053] The specific process of preparing a water-based modified polyamine curing agent is as follows:

[0054] First, 185 kg of trimer acid, 50 kg of soybean oleic acid, 80 kg of isophorone diamine and 200 kg of tetraethylene pentamine were reacted at 200 ° C for 4 hours. Then, they were reacted with 64 kg of epoxy resin (trade name E51) at 100 ° C for 1 hour. The obtained reactant was reacted with 322 kg of emulsifier (polyethylene glycol glycidyl ether, molecular weight: 1750) at 120 ° C for 2 hours, and then with 216 kg of butyl glycidyl ether for chain extension reaction, cooled to 60 ° C and added with 230 kg of water for 1 hour to obtain a water-based modified polyamine curing agent.

[0055] After testing, the water-based modified polyamine curing agent prepared in this embodiment:

[0056] Solid content (%): 79.5

[0057] Viscosity (25℃)cps:21000

[0058] Active hydrogen equivalent (g / mol): 150

[0059] Amine value (mgKOH / g): 208.

[0060] Example 4

[0061] The specific process of preparing a water-based modified polyamine curing agent is as follows:

[0062] First, 165 kg of trimer acid, 45 kg of linoleic acid, 80 kg of isophorone diamine and 200 kg of tetraethylene pentamine were reacted at 200 ° C for 4 hours. Then, they were reacted with 64 kg of epoxy resin (trade name E51) at 100 ° C for 1 hour. The obtained reactant was reacted with 322 kg of emulsifier (polyethylene glycol glycidyl ether, molecular weight: 1750) at 120 ° C for 2 hours, and then with 40 kg of butyl glycidyl ether for chain extension reaction, cooled to 60 ° C and added with 228 kg of water for 1 hour to obtain a water-based modified polyamine curing agent.

[0063] After testing, the water-based modified polyamine curing agent prepared in this embodiment:

[0064] Solid content (%): 78.6

[0065] Viscosity (25℃)cps:20800

[0066] Active hydrogen equivalent (g / mol): 150

[0067] Amine value (mgKOH / g): 188.

[0068] Example 5

[0069] The specific process of preparing a water-based modified polyamine curing agent is as follows:

[0070] First, 100 kg of sebacic acid, 45 kg of tall oil acid, 80 kg of isophorone diamine and 200 kg of tetraethylene pentamine were reacted at 200 ° C for 4 hours. Then, they were reacted with 64 kg of epoxy resin (trade name E51) at 100 ° C for 1 hour. The obtained reactant was reacted with 322 kg of emulsifier (polyethylene glycol glycidyl ether, molecular weight: 1750) at 120 ° C for 2 hours, and then with 50 kg of o-cresol glycidyl ether for chain extension reaction, cooled to 60 ° C and added with 212 kg of water for 1 hour to obtain a water-based modified polyamine curing agent.

[0071] After testing, the water-based modified polyamine curing agent prepared in this embodiment:

[0072] Solid content (%): 80.1

[0073] Viscosity (25℃)cps:20500

[0074] Active hydrogen equivalent (g / mol): 150

[0075] Amine value (mgKOH / g): 198.

[0076] Example 6

[0077] The specific process of preparing a water-based modified polyamine curing agent is as follows:

[0078] First, 96 kg of azelaic acid, 45 kg of linoleic acid, 80 kg of ethylenediamine and 104 kg of pentaethylenehexamine were reacted at 200 ° C for 4 hours. Then, they were reacted with 64 kg of epoxy resin (trade name E51) at 100 ° C for 1 hour. The obtained reactant was then reacted with 322 kg of emulsifier (polyethylene glycol glycidyl ether, molecular weight: 1750) at 120 ° C for 2 hours, and then with 50 kg of phenyl glycidyl ether for chain extension reaction, cooled to 60 ° C, and 187 kg of water was added for 1 hour to obtain a water-based modified polyamine curing agent.

[0079] After testing, the water-based modified polyamine curing agent prepared in this embodiment:

[0080] Solid content (%): 78.5

[0081] Viscosity (25℃)cps:16500

[0082] Active hydrogen equivalent (g / mol): 150

[0083] Amine value (mgKOH / g): 206.

[0084] Comparative Example 1

[0085] A water-based modified polyamine curing agent, the specific process is:

[0086] First, 200 kg of isophorone diamine and 27 kg of epoxy resin (trade name E51) were reacted at 100°C for 1 hour. The obtained reactant was then reacted with 176 kg of emulsifier (polyethylene glycol glycidyl ether, molecular weight: 1750) at 120°C for 2 hours, and then with 62 kg of benzyl glycidyl ether for chain extension reaction, cooled to 60°C and added with 118 kg of water for 1 hour to obtain a water-based modified polyamine curing agent.

[0087] After testing, the water-based modified polyamine curing agent prepared in this embodiment:

[0088] Solid content (%): 79.9;

[0089] Viscosity (25℃)cps:22000;

[0090] Active hydrogen equivalent (g / mol): 150;

[0091] Amine value (mgKOH / g): 208.

[0092] Example 7 Performance Test of Water-Based Modified Polyamine Curing Agent

[0093] The above water-based modified polyamine curing agent was mixed with commercially available E20 epoxy emulsion in a mass ratio of 1:8 to form a metal anti-corrosion coating. After the coating film was cured, the performance index test was carried out according to the chemical industry standard HG / T4759-2014 for water-based epoxy resin metal anti-corrosion coatings. The test results are shown in Table 1:

[0094] Table 1

[0095]

[0096] The experimental results in Table 1 above show that, compared with Comparative Example 1, the polyamine curing agents prepared in Examples 1 to 6 of the present invention can promote epoxy curing and have excellent comprehensive performance. In addition, by comparing Examples 1 to 6, it is found that the polyamine curing agent prepared in Example 5 of the present invention has the best comprehensive performance and has achieved good technical effects.

[0097] The present invention has been described in detail above in conjunction with the embodiments, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A water-based modified polyamine curing agent, characterized in that: The composition comprises the following components in parts by weight: Polybasic organic amine: 10-40 parts, polybasic organic acid: 1-12 parts, monobasic organic acid: 1-12 parts, emulsifier: 0-30 parts, epoxy resin: 1-25 parts, epoxy diluent: 0-35 parts, alcohol ether solvent: 0-22 parts, deionized water 0-60 parts, antioxidant: 0-5 parts.

2. A water-based modified polyamine curing agent according to claim 1, characterized in that: The composition comprises the following components in parts by weight: Polybasic organic amine: 10-38 parts, polybasic organic acid: 1-12 parts, monobasic organic acid: 1-12 parts, emulsifier: 1-30 parts, epoxy resin: 1-25 parts, epoxy diluent: 1-35 parts, alcohol ether solvent: 1-22 parts, deionized water 1-60 parts, antioxidant: 1-5 parts.

3. The water-based modified polyamine curing agent according to claim 1, characterized in that: The polyvalent organic amine includes at least one of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, meta-xylylenediamine and isophoronediamine.

4. The water-based modified polyamine curing agent according to claim 1, characterized in that: The polybasic organic acid includes at least one of dimer acid, trimer acid, sebacic acid, azelaic acid, suberic acid and citric acid.

5. The water-based modified polyamine curing agent according to claim 1, characterized in that: The unit organic acid includes at least one of soybean oleic acid, linoleic acid and tall oil acid.

6. The water-based modified polyamine curing agent according to claim 1, characterized in that: Emulsifiers include polyethylene oxide glycidyl ether, which has a molecular weight of 500-15,000.

7. The water-based modified polyamine curing agent according to claim 1, characterized in that: The epoxy resin includes at least one of liquid or solid bisphenol A epoxy resin, bisphenol F epoxy resin, and novolac epoxy resin.

8. The water-based modified polyamine curing agent according to claim 1, characterized in that: The epoxy diluent includes at least one of butyl glycidyl ether, C12-14 alcohol glycidyl ether, C8-10 alcohol glycidyl ether, butylphenyl glycidyl ether, cardanol glycidyl ether, trimethylolpropane polyglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, polypropylene glycol diglycidyl ether, tertiary carbonic acid glycidyl ether, phenyl glycidyl ether, o-cresol glycidyl ether, nonylphenol glycidyl ether, and benzyl glycidyl ether.

9. The water-based modified polyamine curing agent according to claim 1, characterized in that: The alcohol ether solvent includes at least one of propylene glycol monomethyl ether, ethylene glycol monobutyl ether, dipropylene glycol butyl ether and dipropylene glycol methyl ether; The antioxidant includes at least one of butylated hydroxyanisole, butylated hydroxytoluene, butylated hydroquinone, and antioxidant 1010.

10. The method for preparing the water-based modified polyamine curing agent according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: reacting polyamine, polybasic organic acid and monobasic organic acid according to the ratio at 120-220° C. for 0.5-6 hours to perform amidation reaction to obtain prepolymer 1; S2: adding epoxy resin to prepolymer 1, reacting at 80-120° C. for 0.5-2 hours to obtain prepolymer 2; S3: adding an emulsifier to prepolymer 2, reacting at 85-140° C. for 0.5-2 hours to obtain prepolymer 3; S4: adding epoxy diluent to prepolymer 3 and reacting at 40-70° C. for 2-4 hours to obtain prepolymer 4; S5: Add antioxidant, alcohol ether solvent and deionized water to prepolymer 4 as needed and stir evenly. A water-based modified polyamine curing agent is obtained.

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