A modified epoxy resin and its preparation method

Abstract

This invention provides a modified epoxy resin and its preparation method. The modified epoxy resin is prepared from the following raw materials in parts by weight: 35-55 parts epoxy resin matrix, 18-28 parts pyridine functional monomer, 6-12 parts divalent metal ion source, 12-22 parts curing agent, 1-4 parts accelerator, 0.5-2 parts dispersant, and 8-18 parts solvent. The pyridine functional monomer is a compound containing both epoxy-reactive groups and a pyridine ring. This invention utilizes the synergistic effect of pyridine groups and divalent metal ions, forming a coordination bond that remains stable at room temperature, maintaining the basic properties of the material and achieving a balance between self-healing and performance enhancement with the epoxy resin. The coordination effect between the metal ion and the pyridine ring remains stable in humid and salt spray environments, making it suitable for complex working conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high molecular materials, more particularly to a modified epoxy resin and a preparation method thereof. BACKGROUND

[0002] Epoxy resin is widely used in coating, adhesive, electronic packaging and other fields due to its excellent mechanical strength, chemical stability and bonding properties. However, the cured epoxy resin forms a highly cross-linked static network, which is easy to produce scratches due to external impact, friction and other factors during use. These scratches can damage the integrity of the coating, expose the substrate to corrosive media, and ultimately cause protection failure, significantly shortening the service life of the material. Therefore, further improvement and development are needed. SUMMARY

[0003] In view of the various deficiencies of the prior art, in order to solve the above problems, a modified epoxy resin and a preparation method thereof are proposed, and the following technical solutions are provided:

[0004] A modified epoxy resin is prepared from the following raw materials by mass: epoxy resin matrix 35-55 parts, pyridyl functional monomer 18-28 parts, divalent metal ion source 6-12 parts, curing agent 12-22 parts, accelerator 1-4 parts, dispersant 0.5-2 parts, solvent 8-18 parts, the pyridyl functional monomer is a compound containing both an epoxy reactive group and a pyridine ring.

[0005] Further, the divalent metal ion source is selected from at least one of zinc chloride and ferrous chloride.

[0006] Further, the divalent metal ion source is a mixture of zinc chloride and ferrous chloride, and the mass ratio of zinc chloride to ferrous chloride is 1:1.

[0007] Further, the pyridyl functional monomer is 4-(epoxypropyl)pyridine, 2-vinylpyridine-epoxy propyl ether or 3-methyl-4-pyridyl glycidyl ether.

[0008] Further, the molar ratio of the divalent metal ion source to the pyridyl functional monomer is 1:(3-5).

[0009] Further, the mass ratio of the epoxy resin matrix to the pyridyl functional monomer is (1.5-2.5):1.

[0010] Further, the curing agent is at least one of polyamide 650, modified aromatic amine, methyl tetrahydrophthalic anhydride; the accelerator is at least one of 2,4,6-tris(dimethylaminomethyl)phenol, N,N-dimethylbenzylamine; the dispersant is at least one of BYK-163, tegodispers 750W; the solvent is at least one of ethylene glycol ethyl ether, propylene glycol methyl ether acetate.

[0011] The application also comprises a preparation method of the modified epoxy resin, comprising the following steps:

[0012] S1, the epoxy resin matrix and the pyridyl functional monomer are added into a reaction kettle, an initiator is added, and stirring is carried out at 85-95 DEG C for 2.5-4 h, and the stirring rate is 600-800 r / min, to obtain an epoxy prepolymer containing a pyridyl group;

[0013] S2, the prepolymer obtained in step S1 is cooled to 45-55 DEG C, a divalent metal ion source, a dispersant and a solvent are added, and ultrasonic stirring is used for dispersion, the ultrasonic power is 400-600 W, the stirring rate is 1000-1200 r / min, and the dispersion time is 25-40 min, to obtain a dispersion liquid;

[0014] S3, the curing agent and the accelerator are added into the dispersion liquid of step S2, and stirring and mixing are carried out at 35-45 DEG C for 20-30 min, and the stirring rate is 800-1000 r / min, to obtain the modified epoxy resin.

[0015] In the preparation method of the modified epoxy resin, in step S2, the specific mode of ultrasonic stirring and stirring is that ultrasonic dispersion is carried out for 10-15 min first, then stirring dispersion is carried out for 15-25 min, and the two modes are alternately carried out for 2-3 cycles.

[0016] Due to the above technical scheme, the application has the following beneficial technical effects:

[0017] 1, the pyridyl group and the divalent metal ion are used in cooperation in the application, the two form a coordination bond, which is stable at room temperature, can maintain the basic performance of the material, and realizes the balance between self-healing and performance enhancement of the epoxy resin;

[0018] 2, the coordination of the metal ion and the pyridyl ring in the application is still stable in a humid and salt spray environment, and is suitable for complex working conditions. DETAILED DESCRIPTION

[0019] In order to make the personnel in the art better understand the technical solutions of the present application, the technical solutions of the present application are clearly and completely described below in combination with the embodiments of the present application. Other similar embodiments obtained by the personnel in the art without making creative efforts on the basis of the embodiments in the present application shall all belong to the scope of protection of the present application.

[0020] A modified epoxy resin is prepared from the following raw materials by mass fraction: an epoxy resin matrix 35-55 parts, a pyridyl functional monomer 18-28 parts, a divalent metal ion source 6-12 parts, a curing agent 12-22 parts, an accelerator 1-4 parts, a dispersant 0.5-2 parts, and a solvent 8-18 parts. The pyridyl functional monomer is a compound containing both an epoxy-reactive group and a pyridine ring. The pyridyl group and the divalent metal ion are used in synergy in the present application, and the two form a coordination bond, which is stable at room temperature and can maintain the basic properties of the material, achieving a balance between self-healing and performance enhancement of the epoxy resin. The coordination of the metal ion and the pyridine ring is still stable in a humid and salt spray environment, and is suitable for complex working conditions.

[0021] Specifically, the divalent metal ion source is at least one of zinc chloride and ferrous chloride, the divalent metal ion source is a mixture of zinc chloride and ferrous chloride, the mass ratio of zinc chloride to ferrous chloride is 1:1, the pyridyl functional monomer is 4-(epoxypropyloxy)pyridine, 2-vinylpyridine-epoxypropyl ether, or 3-methyl-4-pyridyl glycidyl ether. The curing agent is at least one of polyamide 650, modified aromatic amine, and methyl tetrahydrophthalic anhydride; the accelerator is at least one of 2,4,6-tris(dimethylaminomethyl)phenol and N,N-dimethylbenzylamine; the dispersant is at least one of BYK-163 and tegodispers 750W; and the solvent is at least one of ethylene glycol ethyl ether, propylene glycol methyl ether acetate.

[0022] The preparation method of the modified epoxy resin comprises the following steps:

[0023] S1, 35-55 parts of an epoxy resin matrix and 18-28 parts of a pyridyl functional monomer are added to a reaction kettle, an initiator is added, and stirring is performed at 85-95℃ for 2.5-4h at a stirring rate of 600-800r / min to obtain an epoxy prepolymer containing a pyridyl group. The pyridyl functional monomer is a compound containing both an epoxy-reactive group and a pyridine ring.

[0024] S2, cooling the prepolymer obtained in step S1 to 45-55℃, adding 6-12 parts of divalent metal ion source, 0.5-2 parts of dispersant and 8-18 parts of solvent, using ultrasonic-stirring synergistic dispersion, ultrasonic dispersion for 10-15 min, ultrasonic power 400-600 W, then stirring dispersion for 15-25 min, stirring speed 1000-1200 r / min, dispersion time 25-40 min, to obtain a dispersion liquid;

[0025] S3, adding 12-22 parts of curing agent and 1-4 parts of accelerator to the dispersion liquid of step S2, stirring and mixing at 35-45℃ for 20-30 min, stirring speed 800-1000 r / min, to obtain the modified epoxy resin.

[0026] Example 1

[0027] S1, adding 46 parts of epoxy resin matrix and 23 parts of 4-(epoxypropyloxy)pyridine into a reaction kettle, adding initiator, stirring and reacting at 90℃ for 3 h, stirring speed 700 r / min, to obtain an epoxy prepolymer containing pyridine groups;

[0028] S2, cooling the prepolymer obtained in step S1 to 50℃, adding 9 parts of a mixture of zinc chloride and ferrous chloride with a mass ratio of 1:1, 1 part of BYK-163 and 12 parts of ethylene glycol ethyl ether, using ultrasonic-stirring synergistic dispersion, ultrasonic dispersion for 12 min, ultrasonic power 500 W, then stirring dispersion for 20 min, stirring speed 1100 r / min, dispersion time 30 min, to obtain a dispersion liquid;

[0029] S3, adding 16 parts of polyamide 650 and 3 parts of 2,4,6-tris(dimethylaminomethyl)phenol to the dispersion liquid of step S2, stirring and mixing at 40℃ for 25 min, stirring speed 900 r / min, to obtain the modified epoxy resin.

[0030] Example 2

[0031] S1, adding 46 parts of epoxy resin matrix and 23 parts of 4-(epoxypropyloxy)pyridine into a reaction kettle, adding initiator, stirring and reacting at 90℃ for 3 h, stirring speed 700 r / min, to obtain an epoxy prepolymer containing pyridine groups;

[0032] S2, cooling the prepolymer obtained in step S1 to 50℃, adding 9 parts of a mixture of zinc chloride and ferrous chloride with a mass ratio of 1:1, 1 part of BYK-163 and 12 parts of ethylene glycol ethyl ether, using ultrasonic-stirring synergistic dispersion, ultrasonic dispersion for 12 min, ultrasonic power 500 W, then stirring dispersion for 20 min, stirring speed 1100 r / min, dispersion time 30 min, to obtain a dispersion liquid;

[0033] S3, 16 parts of polyamide 650 and 3 parts of 2,4,6-tris(dimethylaminomethyl) phenol were added to the dispersion of step S2, stirred and mixed at 40°C for 25 min, and the stirring rate was 900 r / min, to obtain the modified epoxy resin.

[0034] Example 3

[0035] S1, 46 parts of epoxy resin matrix and 23 parts of 4-(epoxypropyloxy)pyridine were added to a reaction kettle, an initiator was added, and the reaction was stirred at 90°C for 3 h, and the stirring rate was 700 r / min, to obtain an epoxy prepolymer containing a pyridine group;

[0036] S2, the prepolymer obtained in step S1 was cooled to 50°C, 9 parts of ferrous chloride, 1 part of BYK-163 and 12 parts of ethylene glycol ethyl ether were added, and ultrasonic stirring and dispersion were used, ultrasonic dispersion was carried out for 12 min, the ultrasonic power was 500 W, and then stirring and dispersion were carried out for 20 min, the stirring rate was 1100 r / min, and the dispersion time was 30 min, to obtain a dispersion;

[0037] S3, 16 parts of polyamide 650 and 3 parts of 2,4,6-tris(dimethylaminomethyl) phenol were added to the dispersion of step S2, stirred and mixed at 40°C for 25 min, and the stirring rate was 900 r / min, to obtain the modified epoxy resin.

[0038] Example 4

[0039] S1, 35 parts of epoxy resin matrix and 18 parts of 2-vinylpyridine-epoxy propyl ether were added to a reaction kettle, an initiator was added, and the reaction was stirred at 90°C for 3 h, and the stirring rate was 700 r / min, to obtain an epoxy prepolymer containing a pyridine group;

[0040] S2, the prepolymer obtained in step S1 was cooled to 50°C, 6 parts of a mixture of zinc chloride and ferrous chloride with a mass ratio of 1:1, 1 part of BYK-163 and 12 parts of ethylene glycol ethyl ether were added, and ultrasonic stirring and dispersion were used, ultrasonic dispersion was carried out for 12 min, the ultrasonic power was 500 W, and then stirring and dispersion were carried out for 20 min, the stirring rate was 1100 r / min, and the dispersion time was 30 min, to obtain a dispersion;

[0041] S3, 16 parts of polyamide 650 and 3 parts of 2,4,6-tris(dimethylaminomethyl) phenol were added to the dispersion of step S2, stirred and mixed at 40°C for 25 min, and the stirring rate was 900 r / min, to obtain the modified epoxy resin.

[0042] Example 5

[0043] S1, 55 parts of epoxy resin matrix and 28 parts of 3-methyl-4-pyridyl glycidyl ether were added to a reaction kettle, an initiator was added, and stirring was carried out at 90°C for 3h, and the stirring rate was 700r / min, to obtain an epoxy prepolymer containing a pyridyl group;

[0044] S2, the prepolymer obtained in step S1 was cooled to 50°C, 12 parts of a mixture of zinc chloride and ferrous chloride with a mass ratio of 1:1, 1 part of BYK-163 and 12 parts of ethylene glycol ether were added, and ultrasonic stirring was used for dispersion, ultrasonic dispersion was carried out for 12min, the ultrasonic power was 500W, and then stirring dispersion was carried out for 20min, the stirring rate was 1100r / min, and the dispersion time was 30min, to obtain a dispersion liquid;

[0045] S3, 16 parts of polyamide 650 and 3 parts of 2,4,6-tris(dimethylaminomethyl) phenol were added to the dispersion liquid of step S2, and stirring was carried out at 40°C for 25min, and the stirring rate was 900r / min, to obtain a modified epoxy resin.

[0046] Example 6

[0047] S1, 46 parts of epoxy resin matrix and 23 parts of 4-(epoxypropyloxy)pyridine were added to a reaction kettle, an initiator was added, and stirring was carried out at 85°C for 2.5h, and the stirring rate was 600r / min, to obtain an epoxy prepolymer containing a pyridyl group;

[0048] S2, the prepolymer obtained in step S1 was cooled to 45°C, 9 parts of a mixture of zinc chloride and ferrous chloride with a mass ratio of 1:1, 0.5 parts of BYK-163 and 8 parts of ethylene glycol ether were added, and ultrasonic stirring was used for dispersion, ultrasonic dispersion was carried out for 10min, the ultrasonic power was 400W, and then stirring dispersion was carried out for 15min, the stirring rate was 1000r / min, and the dispersion time was 25min, to obtain a dispersion liquid;

[0049] S3, 12 parts of polyamide 650 and 1 part of 2,4,6-tris(dimethylaminomethyl) phenol were added to the dispersion liquid of step S2, and stirring was carried out at 35°C for 20min, and the stirring rate was 800r / min, to obtain a modified epoxy resin.

[0050] Example 7

[0051] S1, 46 parts of epoxy resin matrix and 23 parts of 4-(epoxypropyloxy)pyridine were added to a reaction kettle, an initiator was added, and stirring was carried out at 95°C for 4h, and the stirring rate was 800r / min, to obtain an epoxy prepolymer containing a pyridyl group;

[0052] S2. Cool the prepolymer obtained in step S1 to 55°C, add 12 parts of a 1:1 mixture of zinc chloride and ferrous chloride, 2 parts of Tego Dispers 750W and 18 parts of propylene glycol methyl ether acetate, and disperse using a combination of ultrasonication and stirring. Disperse ultrasonically for 15 minutes at an ultrasonic power of 600W, then stir for 25 minutes at a stirring speed of 1200 r / min for a total dispersion time of 40 minutes to obtain a dispersion.

[0053] S3. Add 22 parts of modified aromatic amine and 4 parts of N,N-dimethylbenzylamine to the dispersion in step S2, and stir and mix at 45°C for 30 min at a stirring rate of 1000 r / min to obtain the modified epoxy resin.

[0054] Comparative Example 1

[0055] S1. Add 46 parts of epoxy resin matrix and 23 parts of 4-(epoxypropyloxy)pyridine to a reactor, add an initiator, and stir at 90°C for 3 hours at a stirring rate of 700 r / min to obtain an epoxy prepolymer containing pyridine groups.

[0056] S2. Cool the prepolymer obtained in step S1 to 50°C, add 1 part BYK-163 and 12 parts ethylene glycol ethyl ether, and disperse using a combination of ultrasonication and stirring. Disperse ultrasonically for 12 minutes at an ultrasonic power of 500W, then stir for 20 minutes at a stirring speed of 1100r / min for a total dispersion time of 30 minutes to obtain a dispersion.

[0057] S3. Add 16 parts of curing agent and 3 parts of polyamide 650 to the dispersion in step S2, stir and mix at 40°C for 25 minutes at a stirring rate of 900 r / min to obtain the modified epoxy resin.

[0058] Comparative Example 2

[0059] S1. Add 46 parts of epoxy resin matrix to the reactor, add initiator, stir at 90°C for 3 hours at a stirring rate of 700 r / min to obtain epoxy prepolymer;

[0060] S2. Cool the prepolymer obtained in step S1 to 50°C, add 9 parts of a mixture of zinc chloride and ferrous chloride in a mass ratio of 1:1, 1 part of BYK-163 and 12 parts of ethylene glycol ethyl ether, and disperse using a combination of ultrasonication and stirring. The ultrasonic dispersion is carried out for 12 minutes at an ultrasonic power of 500W, followed by stirring for 20 minutes at a stirring speed of 1100r / min for a total dispersion time of 30 minutes to obtain a dispersion.

[0061] S3. Add 16 parts of curing agent and 3 parts of polyamide 650 to the dispersion in step S2, stir and mix at 40°C for 25 minutes at a stirring rate of 900 r / min to obtain the modified epoxy resin.

[0062] Comparative Example 3

[0063] S1. Add 30 parts of epoxy resin matrix and 30 parts of 4-(epoxypropyloxy)pyridine to a reactor, add an initiator, and stir at 90°C for 3 hours at a stirring rate of 700 r / min to obtain an epoxy prepolymer containing pyridine groups.

[0064] S2. Cool the prepolymer obtained in step S1 to 50°C, add 30 parts of a 1:1 mixture of zinc chloride and ferrous chloride, 1 part of BYK-163 and 12 parts of ethylene glycol ethyl ether, and disperse using a combination of ultrasonication and stirring. Disperse ultrasonically for 12 minutes at an ultrasonic power of 500W, then stir for 20 minutes at a stirring speed of 1100r / min for a total dispersion time of 30 minutes to obtain a dispersion.

[0065] S3. Add 16 parts of polyamide 650 and 3 parts of 2,4,6-tris(dimethylaminomethyl)phenol to the dispersion in step S2, and stir and mix at 40°C for 25 minutes at a stirring rate of 900 r / min to obtain the modified epoxy resin.

[0066] The epoxy resins obtained in Examples 1-7 and Comparative Examples 1-3 were coated onto aluminum alloy substrates to prepare corresponding samples. The samples were cured at 80°C for 2 hours and subjected to pencil hardness test, salt spray test, cross-cut test, and self-healing performance test. The experimental results are shown in Table 1 below.

[0067] Pencil hardness test: Using a set of drawing pencils from 6B to 9H, the pencils are rubbed against the coated surface at a 45-degree angle, and the hardness of the pencil that just fails to scratch the coating is recorded.

[0068] Salt spray test: The above samples were placed in a sealed chamber, and a sodium chloride solution of a specific concentration was sprayed into a fine salt spray continuously at 25°C. After 1000 hours, the samples were removed and the corrosion level on their surfaces was assessed. The corrosion level was assessed using the ISO 4628-3 standard method.

[0069] Cross-cut test: A 2mm grid is formed on the coating surface using a hard cross-cutting tool, requiring the blade to penetrate the coating to the substrate. After cleaning the surface, special adhesive tape is tightly adhered to the grid area and flattened, then quickly peeled off at a 180° angle. Finally, the adhesion grade is recorded based on the proportion of coating peeling area in the grid area by comparing with a standard chart. The adhesion grade is evaluated according to the ISO 2409 standard method.

[0070] Self-healing performance test: Place the sample at 25°C, use a sharp blade to make a scratch that penetrates the coating on the surface, let it stand for 30 minutes and then conduct a salt spray test, and record the time when the scratch begins to rust.

[0071] Table 1 Performance tests of Examples 1-7 and Comparative Examples 1-3

[0072]

[0073] As shown in Table 1, Example 1 achieved top-tier performance in all tests, exhibiting the most balanced and excellent performance. Examples 2 and 3, which did not use the mixture of zinc chloride and ferrous chloride with the pyridine functional monomer, showed slightly inferior corrosion resistance, adhesion, and self-healing ability compared to Example 1. Examples 4-5 adjusted the ratio of epoxy resin matrix, pyridine functional monomer, and divalent metal ion source; their coatings exhibited slightly weaker self-healing capabilities than Example 1, but significantly stronger than the comparative example. Examples 6-7 adjusted parameters such as the power and temperature of ultrasonic-stirring dispersion and polymerization temperature; their coating hardness at 3H was slightly weaker than Example 1, but significantly stronger than the comparative example.

[0074] Comparative Example 1 did not contain a divalent metal ion source, and Comparative Example 2 did not contain a pyridine functional monomer. When the scratch penetrated the coating, the corrosive medium directly exposed the metal substrate. Because the pyridine functional monomer and divalent metal ion source in the coatings of Comparative Examples 1 and 2 prevented the pyridine groups from forming coordination bonds, they could not repair or seal the damage points, resulting in a salt spray test rusting time of only 20 hours for damaged coatings. The coating obtained in Comparative Example 3, where the ratio of epoxy resin matrix, pyridine functional monomer, and divalent metal ion source was outside the scope of this application, exhibited significantly weaker hardness, corrosion resistance, adhesion, and self-healing ability compared to the examples. This indicates that the epoxy resin obtained using the new technology formulation ratio in the examples performed better than that obtained in the comparative examples.

[0075] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A modified epoxy resin, characterized by, Prepared from the following raw materials by mass parts: epoxy resin matrix 35-55 parts, pyridine-based functional monomer 18-28 parts, divalent metal ion source 6-12 parts, curing agent 12-22 parts, accelerator 1-4 parts, dispersant 0.5-2 parts, solvent 8-18 parts, the pyridine-based functional monomer is a compound containing both epoxy reactivity group and pyridine ring; The divalent metal ion source is selected from a mixture of zinc chloride and ferrous chloride, and the mass ratio of zinc chloride to ferrous chloride is 1:1; The pyridine-based functional monomer is 4-(epoxypropyl) pyridine, 2-vinylpyridine-epoxy propyl ether or 3-methyl-4-pyridyl glycidyl ether.

2. The modified epoxy resin according to claim 1, characterized in that The molar ratio of the divalent metal ion source to the pyridine-based functional monomer is 1:3-5.

3. The modified epoxy resin according to claim 1, characterized in that, The mass ratio of the epoxy resin matrix to the pyridine-based functional monomer is 1.5-2.5:

1.

4. The modified epoxy resin of claim 1, wherein The curing agent is at least one of polyamide 650, modified aromatic amine, methyl tetrahydrophthalic anhydride; the accelerator is at least one of 2,4,6-tris(dimethylaminomethyl) phenol, N,N-dimethylbenzylamine; the dispersant is at least one of BYK-163 dispersant, TEGO Dispers 750W; the solvent is at least one of ethylene glycol ethyl ether, propylene glycol methyl ether acetate.

5. A process for the preparation of the modified epoxy resin according to any one of claims 1 to 4, characterized in that, Comprising the following steps: S1, the epoxy resin matrix and the pyridine-based functional monomer are added to the reaction kettle, the initiator is added, and the stirring reaction is carried out at 85-95℃ for 2.5-4h, the stirring rate is 600-800r / min, and the epoxy prepolymer containing pyridine groups is obtained; S2, the prepolymer obtained in step S1 is cooled to 45-55℃, the divalent metal ion source, the dispersant and the solvent are added, and the ultrasonic-stirring synergistic dispersion is carried out, the ultrasonic power is 400-600W, the stirring rate is 1000-1200r / min, the dispersion time is 25-40min, and the dispersion liquid is obtained; S3, the curing agent and the accelerator are added to the dispersion liquid of step S2, and stirred and mixed at 35-45℃ for 20-30min, the stirring rate is 800-1000r / min, and the modified epoxy resin is obtained.

6. The method for preparing a modified epoxy resin according to claim 5, characterized in that, In step S2, the specific way of ultrasonic-stirring synergistic dispersion is: first ultrasonic dispersion for 10-15min, then stirring dispersion for 15-25min, and alternately for 2-3 cycles.

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