A curable epoxy resin composition, its preparation and use

Abstract

The application discloses a curable epoxy resin composition and a preparation method and application thereof, and the composition comprises the following raw materials in a weight ratio: 25-90% of an epoxy resin, 1-50% of an amine curing agent, and 1-50% of an active diluent, wherein the active diluent is selected from at least one compound with a structure shown in the following formula. In the application, the epoxy resin composition can achieve excellent mechanical properties and thermal performance effects under low-temperature curing conditions, and exhibits better adhesion on metal and concrete surfaces.

Description

Technical Field

[0001] This invention relates to an epoxy resin composition, and more particularly to a curable epoxy resin composition, its preparation method, and its application. Background Technology

[0002] Epoxy resin is widely used in civil engineering, electronics, aerospace, automotive machinery and other fields, and is an important part of national production. However, epoxy resin itself has a high viscosity, generally being a high-viscosity liquid or solid. When combined with a curing agent, a diluent is often added to reduce viscosity to meet the actual construction needs.

[0003] Diluents suitable for epoxy resin compositions are generally divided into two categories: small-molecule volatile organic compounds and reactive diluents with active functional groups that can participate in crosslinking reactions. Volatile organic compounds, such as xylene and acetone, are gradually being banned due to environmental concerns, while reactive diluents, such as butyl glycidyl ether and ethylene glycol diglycidyl ether, are mainly limited to epoxy resin components and are difficult to apply directly to curing agent components, thus failing to meet the needs of specific application scenarios.

[0004] Currently, there are very few types of reactive diluents for curing agents on the market. The main reason is that aliphatic primary amines, such as ethylenediamine, are highly reactive and relatively volatile; benzylamine and similar substances readily react with water and carbon dioxide in the air to form carbonates in epoxy compositions; and while end-capping substitution of aliphatic diamines can reduce reactivity and increase working time, it significantly reduces the mechanical properties and heat resistance of the epoxy composition, which is not suitable for the development needs of epoxy resins.

[0005] Patent CN110945050A discloses a cyclohexyl secondary amine compound as a reactive diluent for epoxy resins. Reportedly, the cured epoxy resin obtained exhibits considerably favorable mechanical, chemical, and thermal properties. However, in the diluent structure of this patent, both secondary amine groups are directly linked to the aliphatic ring, resulting in excessively low reactivity with the epoxy resin. It requires high-temperature curing; otherwise, incomplete curing prevents the achievement of favorable mechanical properties and may even severely affect the resin's mechanical properties and heat resistance. Summary of the Invention

[0006] To address the above technical problems, this invention proposes a curable epoxy resin composition, its preparation method, and its application.

[0007] The first objective of this invention is to provide a curable epoxy resin composition. This composition uses a compound of formula I as a reactive diluent, which not only exhibits good system compatibility but also extends the working time of the cured product while providing a low initial viscosity. Furthermore, it achieves excellent mechanical and thermal properties under low-temperature curing conditions and demonstrates good adhesion to metal and concrete surfaces.

[0008] A second objective of this invention is to provide a method for preparing a curable epoxy resin composition. The method is simple and easy to apply.

[0009] A third object of the present invention is to provide an application of a curable epoxy resin composition.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A curable epoxy resin composition comprising the following raw materials in the indicated weight ratios:

[0012] Epoxy resin 25-90%, preferably 50-90%, more preferably 60-80%

[0013] Amine curing agent 1-50%, preferably 5-30%, more preferably 10-20%.

[0014] The reactive diluent is 1-50%, preferably 5-30%, and more preferably 10-20%.

[0015] Specifically, in the epoxy resin composition of the present invention, the proportion of epoxy resin can be adjusted within a certain range depending on the type of amine curing agent. For example, when the amine curing agent is a basic amine such as 4,4'-diaminodicyclohexylmethane or isophorone diamine, the proportion of epoxy resin can be appropriately increased; while when the amine curing agent is a modified product of the basic amine, such as an amidated modified product of the above-mentioned basic amines, the proportion of epoxy resin may be reduced. These situations are well known to those skilled in the art of epoxy resins and mainly depend on the specific selection of the amine curing agent.

[0016] The active diluent is selected from at least one compound having the structure shown in Formula I:

[0017]

[0018] R1 is selected from H, hydroxyl, amino, C1-C 12 Alkyl groups, preferably H, hydroxyl, or methyl;

[0019] R2 is selected from alkyl or unsaturated alkyl, alkoxy or unsaturated alkoxy, aryl, aralkyl, aralkoxy, preferably alkyl or unsaturated alkyl, alkoxy or unsaturated alkoxy, aryl, aralkyl, aralkoxy, containing at least one hydroxyl group and one secondary amino group.

[0020] In a preferred embodiment of the present invention, the reactive diluent is selected from the following compounds:

[0021]

[0022]

[0023] The active diluent described in this invention can be directly purchased from commercially available finished products when it is a known commercial raw material, and can also be customized and synthesized by a simple method when it is not a known commercial raw material.

[0024] For example, most of the above reactive diluents can be synthesized using the following preparation process:

[0025] Cyclohexylamine compounds and glycidyl ether compounds (or styrene oxide, ethylene oxide, etc.) are mixed and reacted under stirring conditions at 30-100°C. After the reaction is complete, the mixture is cooled and discharged. The molar ratio of cyclohexylamine compounds to glycidyl ether compounds is preferably 1:(0.5-1.5), more preferably 1:(0.9-1.1), and the reaction time is, for example, 1-5 hours.

[0026] The cyclohexylamine compound is a cycloalkanes containing at least one amino group, preferably cycloalkanes containing 1-4 amino groups, and at least one amino group is a primary amino group;

[0027] The glycidyl ether compound is an aliphatic or aromatic glycidyl ether, especially any raw material that can react with cyclohexylamine compounds to produce the active diluent shown in Formula I.

[0028] It should be noted that the above process is only a specific example of one implementation scheme and does not limit the source of the reactive diluent described in this invention.

[0029] In a preferred embodiment of the present invention, the epoxy resin is selected from one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, phenolic epoxy resin, glycidyl ether type epoxy resin, and glycidyl amine type epoxy resin, preferably one or more of epoxy resin E51, epoxy resin E44, epoxy resin E20, benzyl glycidyl ether, phenyl glycidyl ether, C12-C14 glycidyl ether, butyl glycidyl ether, 1,4-butanediol diglycidyl ether, and 1,2-ethylene glycol diglycidyl ether.

[0030] In a preferred embodiment of the present invention, the amine curing agent is one or more of the following: aliphatic amines, alicyclic amines, aromatic amines, polyether amines, or their modifiers, which contain at least one primary amine group;

[0031] Preferably, the fatty amine is one or more selected from ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentanediamine, methylpentanediamine, hexanediamine, N-(2-ethylamino)-1,3-propanediamine, and N,N'-di(3-aminopropyl)-1,2-ethylenediamine;

[0032] Preferably, the alicyclic amine is isophorone diamine, 1,3-cyclohexanedimethylamine, 4,4'-diaminodicyclohexylmethane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 1-methyl-2,4-cyclohexanediamine, 1,2-diaminocyclohexane, N-cyclohexyl-1,3-propanediamine, cyclohexylamine, N... 1 -(3-aminopropyl)-N 3 -Cyclohexyl-1,3-propanediamine, N 1 -(3-aminopropyl)-N 3 One or more of methylcyclohexyl-1,3-propanediamine;

[0033] Preferably, the aromatic amine is one or more selected from 4,4'-diaminodiphenylmethane, m-phenylenediamine, toluenediamine, and diethyltoluenediamine;

[0034] Preferably, the polyetheramine is one or more of Wanamine 8100, Wanamine 8200, Jeffamine D2000, Jeffamine T403, Jeffamine D220, Jeffamine D400, and Jeffamine T5000.

[0035] Preferably, the modified aliphatic amine, alicyclic amine, aromatic amine, or polyether amine can be a modified amine compound obtained through the following chemical modifications: Mannich modification, amidation, or epoxy addition.

[0036] As a preferred embodiment of the present invention, the epoxy resin composition may optionally include one or more of pigments, fillers, dispersants, leveling agents, defoamers, wetting agents, coupling agents, flame retardants, plasticizers, and diluents as additives.

[0037] As pigments and fillers suitable for the present invention, pigments and filler components known in the coating field, such as calcium carbonate, barium sulfate, silica powder, titanium dioxide, carbon black, talc, nano clay, and graphite, can be selected.

[0038] BYK-190, BYK-192, etc. can be selected as dispersants suitable for this invention.

[0039] As a leveling agent suitable for the present invention, BYK-333, TEGO Glide 407, etc. can be selected.

[0040] As a defoamer suitable for the present invention, BYK-012, BYK-028, tego FOAMEX 810, etc. can be selected.

[0041] As a wetting agent suitable for the present invention, tego270, tego4100, etc. can be selected.

[0042] As a coupling agent suitable for the present invention, KH550, KH560, KH792, etc. can be selected.

[0043] Clariant Exolit RP 6500 or similar flame retardants can be used as suitable flame retardants for this invention.

[0044] As a plasticizer suitable for the present invention, well-known plasticizer components in the coatings field such as dioctyl phthalate, soybean oil ester, methyl oleate, and epoxidized methyl oleate can be selected.

[0045] As a diluent suitable for this invention, conventional diluents such as water, benzyl alcohol, xylene, and n-butanol can be selected.

[0046] A method for preparing a curable epoxy resin composition as described above, characterized by comprising the following steps:

[0047] Epoxy resin, amine curing agent, and reactive diluent are directly mixed to obtain an epoxy resin composition; and / or,

[0048] The amine curing agent and reactive diluent are premixed and then mixed evenly with epoxy resin to obtain an epoxy resin composition.

[0049] Application of a curable epoxy resin composition as described above or a curable epoxy resin composition prepared by the method described above.

[0050] A coating prepared from the curable epoxy resin composition described above or the curable epoxy resin composition prepared by the method described above.

[0051] An adhesive prepared from the curable epoxy resin composition described above or the curable epoxy resin composition prepared by the method described above.

[0052] A composite material prepared from the curable epoxy resin composition described above or the curable epoxy resin composition prepared by the method described above.

[0053] This application has the following technical advantages:

[0054] (1) The present invention uses amine compounds with the structure of Formula I as diluents for epoxy resin compositions. These compounds have low viscosity and low saturated vapor pressure, and can be used to make environmentally friendly epoxy adhesives, coatings and composite materials, etc., and provide lower initial viscosity of the product.

[0055] (2) In the epoxy resin composition of the present invention, the amine compound of formula I can be used as an epoxy resin diluent to crosslink and cure with the epoxy resin as an active diluent, and can have multiple active crosslinking points;

[0056] (3) The amine compounds of Formula I in the epoxy resin composition of the present invention have good compatibility with epoxy resin. While playing a diluting role, they can also provide a longer working time, better toughness, good mechanical and thermal properties under heating and no heating, and good adhesion to metal and concrete surfaces.

[0057] (4) The amine compounds of Formula I in the epoxy resin composition of the present invention can be used alone or in combination with other epoxy resin diluents, which is of great significance for expanding the selection of diluents. Detailed Implementation

[0058] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0059] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0060] The names, abbreviations, and sources of the main chemicals used in the embodiments of this invention are shown in the table below. Unless otherwise specified, all reagents used are of analytical grade.

[0061] The main raw material information involved in the following specific implementation methods is shown in Table 1:

[0062] Table 1. Information on Main Raw Materials

[0063]

[0064]

[0065] The main testing methods used in this invention are as follows:

[0066] (1) Viscosity test: The viscosity of the material at 25°C was tested using a Bollerfeld viscometer.

[0067] (2) Glass transition temperature (Tg) test: Test standard ISO 11358.

[0068] (3) Mechanical property testing: The tensile strength and tensile elongation at break are tested according to the methods in GBT1039-1992 General Rules for Mechanical Properties of Plastics.

[0069] (4) Adhesion test of paint film: The adhesion test of metal surface is carried out according to the method in GB / T9286—1998 "Cross-cut test of paint and varnish film". The test level is divided into 0-5 according to the standard record. The smaller the value, the better the adhesion.

[0070]

Preparation of Example 1

[0071]

[0072] Cyclohexylamine was added to a three-necked flask and heated to 80°C with stirring. equimolar amounts of benzyl glycidyl ether were then added dropwise to initiate the reaction. After the addition was complete, the mixture was kept at this temperature for 3 hours, then cooled and discharged to obtain active diluent I.

[0073] 1H NMR spectrum: 1 H NMR (CDCl3, 400MHz, TMS): δ7.29(s,4H),7.3(s,1H),5.5(t,H),5.32(t,H),4.6(s,2H),3.7(m,H),3. 62(s,2H),2.7(s,2H),2.56(m,H),1.61(t,2H),1.45(m,2H),1.36(t,2H),1.21(m,2H),1.11(m,2H).

[0074]

Preparation of Example 2

[0075]

[0076] N-cyclohexyl-1,3-propanediamine was added to a three-necked flask and heated to 80°C with stirring. An equimolar ratio of C12 glycidyl ether was added dropwise to carry out the reaction. After the addition was complete, the reaction was kept at the temperature for 3 hours, and then cooled and discharged to obtain active diluent II.

[0077] [Preparation Example 3]

[0078]

[0079] N 1 -(3-aminopropyl)-N 3 Cyclohexyl-1,3-propanediamine was added to a three-necked flask and heated to 80°C with stirring. Butyl glycidyl ether was added dropwise to carry out the reaction. After the addition was complete, the reaction was kept at the temperature for 3 hours, and then cooled and discharged to obtain active diluent III.

[0080] [Preparation Example 4]

[0081]

[0082] N 1 -(3-aminopropyl)-N 3 Cyclohexyl-1,3-propanediamine was added to a three-necked flask and heated to 80°C with stirring. An equimolar ratio of phenyl glycidyl ether was then added dropwise to initiate the reaction. After the addition was complete, the reaction was maintained at this temperature for 3 hours, and then the mixture was cooled and discharged to obtain reactive diluent IV.

[0083] [Preparation Example 5]

[0084]

[0085]

[0086] N 1 -(3-aminopropyl)-N 3 1,3-Methylcyclohexyl-1,3-propanediamine was added to a three-necked flask and heated to 100°C with stirring. Styrene oxide was added dropwise in an equimolar ratio to carry out the reaction. After the addition was complete, the reaction was kept at the temperature for 4 hours, and then the mixture was cooled and discharged to obtain reactive diluent V.

[0087] [Preparation Example 6]

[0088]

[0089] N 1 -(3-aminopropyl)-N 3 1,3-Methylcyclohexyl-1,3-propanediamine was added to a three-necked flask and heated to 90°C with stirring. Butyl glycidyl ether was added dropwise to carry out the reaction. After the addition was complete, the reaction was kept at the temperature for 3 hours, and then cooled and discharged to obtain active diluent VI.

[0090]

Examples 1-7

[0091] Different epoxy resin compositions were prepared according to the following methods:

[0092] The amine curing agent and reactive diluent were mixed according to the types and amounts of raw materials shown in Table 2, and then mixed evenly with epoxy resin to obtain an epoxy resin composition.

[0093] Table 2. Different raw material selections and dosages (g) in Examples 1-7

[0094]

[0095]

[0096] Comparative Example 1

[0097] An epoxy resin composition was prepared according to a formulation that was essentially the same as that in Example 3, except that reactive diluent I was replaced with C12-C14 glycidyl ether.

[0098] Comparative Example 2

[0099] An epoxy resin composition was prepared according to a formulation that was essentially the same as that in Example 3, except that reactive diluent I was replaced with N,N'-diisopropylmethylcyclohexanediamine provided in Example 1 of patent CN110945050A.

[0100] The performance tests listed in Table 3 were performed on the heat-cured and room-temperature-cured epoxy resin compositions prepared in each embodiment and comparative example. The viscosity of each reactive diluent was also tested, and the results are as follows:

[0101] Table 3. Performance Test Results

[0102]

[0103]

[0104] The epoxy resin composition was heated at 80°C for 2 hours and then at 100°C for 2 hours to obtain a heat-cured epoxy resin composition; the epoxy resin composition was cured at 25°C for 7 days to obtain a room-temperature cured epoxy resin composition.

[0105] The test results above show that the epoxy resin compositions in Examples 1-7 of this invention exhibit good heat resistance and high mechanical properties under both high-temperature and room-temperature curing conditions. They also demonstrate good adhesion to the substrate surface and excellent bonding performance, making them highly practical. Furthermore, the compositions in Examples 2-5 show significantly better tensile strength under room-temperature curing compared to the composition in Example 1. In Example 7, replacing reactive diluent I with reactive diluent III in Example 1 also significantly improves the tensile strength under room-temperature curing. This indicates that reactive diluents in this invention, with two or more secondary amine groups, at least one of which is interleaved with an aliphatic ring, are more beneficial for improving the mechanical properties of the cured product, such as elongation at break, compared to reactive diluents with only one mono-secondary amine group directly connected to an aliphatic ring. This results in superior product performance and makes this a more desirable alternative.

[0106] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A curable epoxy resin composition, characterized in that, The raw materials include the following ingredients in the indicated weight ratios: Epoxy resin 25-90%, Amine curing agent 1-50%, Reactive diluent 1-50%, The active diluent is selected from at least one compound having the structure shown in Formula I: Equation I, R1 is selected from H, hydroxyl, amino, and C1-C12 alkyl; R2 is selected from alkyl or unsaturated alkyl, alkoxy or unsaturated alkoxy, aryl, aralkyl, and aralkoxy groups containing at least one hydroxyl group.

2. The curable epoxy resin composition according to claim 1, characterized in that, The raw materials include the following ingredients in the indicated weight ratios: Epoxy resin 50-90%, Amine curing agent 5-30%, 5-30% reactive diluent.

3. The curable epoxy resin composition according to claim 1, characterized in that, The raw materials include the following ingredients in the indicated weight ratios: Epoxy resin 60-80%, 10-20% amine curing agent 10-20% reactive diluent.

4. The curable epoxy resin composition according to claim 1, characterized in that, In Formula I, R1 is selected from H, hydroxyl, and methyl.

5. The curable epoxy resin composition according to claim 1, characterized in that, In the formula, R2 is selected from alkyl or unsaturated alkyl, alkoxy or unsaturated alkoxy, aryl, aralkyl, and aralkoxy groups that contain at least one hydroxyl group and one secondary amino group.

6. The curable epoxy resin composition according to claim 1, characterized in that, The reactive diluent is selected from the following compounds: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 。 7. The curable epoxy resin composition according to any one of claims 1-6, characterized in that, The epoxy resin is selected from one or more of glycidyl ether type epoxy resin and glycidyl amine type epoxy resin.

8. The curable epoxy resin composition according to claim 7, characterized in that, The epoxy resin is selected from one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, and phenolic epoxy resin.

9. The curable epoxy resin composition according to claim 7, characterized in that, The epoxy resin is selected from one or more of epoxy resin E51, epoxy resin E44, and epoxy resin E20.

10. The curable epoxy resin composition according to any one of claims 1-6, characterized in that, The amine curing agent is one or more of the following: aliphatic amines, cycloaliphatic amines, aromatic amines, polyether amines, or their modifiers, which contain at least one primary amine group.

11. The curable epoxy resin composition according to claim 10, characterized in that, The fatty amine is one or more of the following: ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentamethylenediamine, methylpentanediamine, hexamethylenediamine, N-(2-ethylamino)-1,3-propanediamine, and N,N'-di(3-aminopropyl)-1,2-ethylenediamine.

12. The curable epoxy resin composition according to claim 10, characterized in that, The alicyclic amine is one or more of the following: isophorone diamine, 1,3-cyclohexanedimethylamine, 4,4'-diaminodicyclohexylmethane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 1-methyl-2,4-cyclohexanediamine, 1,2-diaminocyclohexane, N-cyclohexyl-1,3-propanediamine, cyclohexylamine, N1-(3-aminopropyl)-N3-cyclohexyl-1,3-propanediamine, and N1-(3-aminopropyl)-N3-methylcyclohexyl-1,3-propanediamine.

13. The curable epoxy resin composition according to claim 10, characterized in that, The aromatic amine is one or more of 4,4'-diaminodiphenylmethane, m-phenylenediamine, toluenediamine, and diethyltoluenediamine.

14. The curable epoxy resin composition according to claim 10, characterized in that, The polyetheramine is one or more of Wanamine 8100, Wanamine 8200, Jeffamine D2000, Jeffamine T403, Jeffamine D220, Jeffamine D400, and Jeffamine T5000.

15. The curable epoxy resin composition according to any one of claims 1-6, characterized in that, The epoxy resin composition may optionally include one or more of pigments, fillers, dispersants, leveling agents, defoamers, wetting agents, coupling agents, flame retardants, plasticizers, and diluents as additives.

16. A method for preparing a curable epoxy resin composition according to any one of claims 1-15, characterized in that, Includes the following steps: Epoxy resin, amine curing agent, and reactive diluent are directly mixed to obtain an epoxy resin composition; and / or, The amine curing agent and reactive diluent are premixed and then mixed evenly with epoxy resin to obtain an epoxy resin composition.

17. A coating prepared from a curable epoxy resin composition according to any one of claims 1-15 or a curable epoxy resin composition obtained by the method of claim 16.

18. An adhesive prepared from a curable epoxy resin composition according to any one of claims 1-15 or a curable epoxy resin composition obtained by the method of claim 16.

19. A composite material prepared from the curable epoxy resin composition according to any one of claims 1-15 or the curable epoxy resin composition obtained by the method of claim 16.

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