Bromine-containing flame-retardant epoxy resin curing agent and preparation method thereof

Abstract

The present invention discloses a bromine-containing flame-retardant epoxy resin curing agent and a preparation method thereof. The bromine-containing flame-retardant epoxy resin curing agent is prepared by a Mannich reaction of 35-45% 2-bromophenol, 10-25% amine, and 25-50% aldehyde. Performance testing shows that the prepared epoxy resin curing agent not only possesses the characteristics of a typical Mannich-type epoxy resin curing agent, such as fast drying and high hardness, but also has excellent fire resistance and flame retardancy. It is suitable for epoxy coatings and adhesives requiring flame retardancy, achieving excellent technical results.

Description

Technical Field

[0001] The present invention relates to an epoxy resin curing agent, in particular to a bromine-containing flame-retardant epoxy resin curing agent with fast curing speed, good mechanical properties, fire resistance and excellent flame retardancy, and a preparation method thereof, belonging to the technical field of polymer materials. Background Art

[0002] Epoxy resins form a three-dimensional network structure when reacting with curing agents. After curing, they exhibit excellent mechanical, electrical, and chemical resistance properties. Therefore, epoxy resins are often used in fiber-reinforced materials, adhesives, anti-corrosion coatings, floor coatings, and other fields.

[0003] Entering the 21st century, the application of polymer materials has become increasingly widespread. Human social development and people's lives have become inseparable from their use. At the same time, people's demands for a more comfortable living environment are also becoming increasingly demanding. The loss of life and property caused by the combustion of polymer materials in fires is not only a matter of concern to government agencies, but also a matter of great concern to consumers and businesses. Consequently, flame-retardant polymer materials have become a key component of new material development and application.

[0004] Flame-retardant polymer materials are primarily produced through two approaches: additive and reactive. Additive methods typically involve physically adding flame retardants to polymer materials. Reactive flame-retardant materials can be synthesized through novel molecular design to create inherently flame-retardant polymers, or by copolymerizing existing polymers with flame-retardant compounds to introduce flame-retardant structural units into the polymer's main chain or side chains. Flame-retardant materials generally contain certain flame-retardant chemical elements, primarily including nitrogen, phosphorus, chlorine, bromine, boron, aluminum, and silicon. Summary of the Invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a bromine-containing flame-retardant epoxy resin curing agent with fast curing speed and good fire resistance to meet the needs of epoxy coatings and adhesives with fire resistance and flame retardancy requirements; another purpose of the present invention is to provide a preparation method of the epoxy resin curing agent.

[0006] Technical solution: To achieve the above objectives, the technical solution adopted by the present invention is:

[0007] A bromine-containing flame-retardant epoxy resin curing agent is prepared from the following raw materials in percentage by mass: 35-45% of 2-bromophenol, 10-25% of amine substances, and 25-50% of aldehyde substances.

[0008] As a preferred embodiment, the bromine-containing flame-retardant epoxy resin curing agent is characterized in that the molar ratio of 2-bromophenol, polyamines and aldehydes is 1:2:1.

[0009] As a preferred embodiment, the bromine-containing flame-retardant epoxy resin curing agent described above, the polyamine substance is one or a mixture of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexyleneheptamine, pentamethylenediamine, hexamethylenediamine, isophoronediamine, 1,3-cyclohexanedimethylamine, 4,4-diaminodiphenylmethane, m-xylylenediamine, cyclohexanediamine, and cyclopentanediamine.

[0010] As a preferred embodiment, in the above-mentioned bromine-containing flame-retardant epoxy resin curing agent, the aldehyde substance is one or a mixture of formaldehyde solution, acetaldehyde solution, butyraldehyde solution.

[0011] The method for preparing the bromine-containing flame-retardant epoxy resin curing agent of the present invention comprises the following steps:

[0012] (1) Add 2-bromophenol and polyamines according to mass percentage or molar ratio into a reaction flask, stir and heat to mix the materials evenly;

[0013] (2) adding the measured aldehyde substances into the high-level tank;

[0014] (3) dripping the aldehydes in the header tank into the reaction flask;

[0015] (4) After the addition is complete, continue the reaction at room temperature;

[0016] (5) After the insulation is completed, turn on the vacuum pump to remove the water generated by the reaction;

[0017] (6) cooling and filtering, and packaging to obtain the finished product of bromine-containing flame-retardant epoxy resin curing agent.

[0018] As a preferred embodiment, the method for preparing the bromine-containing flame-retardant epoxy resin curing agent of the present invention comprises the following steps:

[0019] (1) Add 2-bromophenol and polyamines according to mass percentage into a reaction flask, stir and heat to mix the materials evenly;

[0020] (2) adding the measured aldehyde substances into the high-level tank;

[0021] (3) Add the aldehydes in the header tank to the reaction flask while controlling the temperature at 50-70°C;

[0022] (4) After the addition is complete, heat the mixture at 70-90°C for 2-4 hours;

[0023] (5) After the insulation is completed, turn on the vacuum pump to remove the water generated by the reaction;

[0024] (6) cooling and filtering, and packaging to obtain the finished product of bromine-containing flame-retardant epoxy resin curing agent.

[0025] As a preferred embodiment, in the above method for preparing a bromine-containing flame-retardant epoxy resin curing agent, in step (3), the aldehyde substance in the header tank is dripped into the reaction flask, and the temperature is optimally controlled at 70°C. In step (4), the reaction temperature is 80°C and the reaction time is 3 hours.

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

[0027] The product of the present invention uses a Mannich-type epoxy resin curing agent as its base structure, exhibiting rapid curing speed, excellent mechanical properties, and corrosion resistance. Furthermore, the introduction of bromine using 2-bromophenol enhances the system's fire resistance and flame retardancy, making it suitable for use in construction and electronic materials applications requiring fire protection.

[0028] During the experiment, the present invention found that the amount of 2-bromophenol is critical. If the amount of 2-bromophenol is less than the amount of the present invention, the fire resistance and flame retardant properties of the curing agent are not significantly improved compared with the ordinary Mannich-type epoxy curing agent; if the amount of 2-bromophenol is more than the amount of the present invention, the viscosity of the curing agent increases, resulting in the need to add a diluent during use and affecting its flame retardant properties. In addition, if the amount of aldehyde substance is more than the amount of the present invention, it will also increase the viscosity of the curing agent, which will also result in the need to add a diluent during use of the curing agent and affect its flame retardant properties. Therefore, the optimal molar ratio of phenol, aldehyde, and amine screened by the present invention is 1:2:1

[0029] After performance testing, the results show that the prepared epoxy resin curing agent not only has the characteristics of quick drying and high hardness of general Mannich-type epoxy resin curing agents, but also has good fire resistance and flame retardant properties. It is suitable for construction and electronic materials fields with fire protection requirements, and has achieved very good technical results. DETAILED DESCRIPTION

[0030] Example 1

[0031] 1. A bromine-containing flame-retardant epoxy resin curing agent, which is made from the following raw materials in percentage by mass:

[0032] 44% 2-bromophenol, 15% ethylenediamine, 41% formaldehyde solution (phenol, aldehyde, amine molar ratio 1:2:1).

[0033] 2. A method for preparing a bromine-containing flame-retardant epoxy resin curing agent, comprising the following steps:

[0034] (1) Add 346 g of 2-bromophenol and 120 g of ethylenediamine into a reaction flask and stir to mix the materials evenly;

[0035] (2) 324 g of 37% formaldehyde solution was added to the header tank;

[0036] (3) Add the 37% formaldehyde solution in the header tank dropwise into the reaction flask while controlling the temperature at 70°C.

[0037] (4) After the addition was complete, the reaction was kept at 80°C for 3 hours;

[0038] (5) After the insulation is completed, turn on the vacuum pump to remove the water generated by the reaction;

[0039] (6) cooling and filtering, and packaging to obtain the finished product of bromine-containing flame-retardant epoxy resin curing agent.

[0040] Example 2

[0041] 1. A bromine-containing flame-retardant epoxy resin curing agent, which is made from the following raw materials in percentage by mass:

[0042] 41% 2-bromophenol, 25% diethylenetriamine, 34% butyraldehyde (phenol, aldehyde, amine molar ratio 1:2:1).

[0043] 2. A method for preparing a bromine-containing flame-retardant epoxy resin curing agent, comprising the following steps:

[0044] (1) Add 346 g of 2-bromophenol and 206 g of diethylenetriamine into a reaction flask and stir to mix the materials evenly;

[0045] (2) Add 288 g of butyraldehyde into the header tank;

[0046] (3) Add butyraldehyde from the header tank to the reaction flask while controlling the temperature at 70°C.

[0047] (4) After the addition was complete, the reaction was kept at 80°C for 3 hours;

[0048] (5) After the heat preservation is completed, the mixture is cooled and filtered, and then packaged to obtain the finished bromine-containing flame-retardant epoxy resin curing agent.

[0049] Example 3

[0050] 1. A bromine-containing flame-retardant epoxy resin curing agent, which is made from the following raw materials in percentage by mass:

[0051] 38% 2-bromophenol, 13% ethylenediamine, 49% acetaldehyde solution (phenol, aldehyde, amine molar ratio 1:2:1).

[0052] 2. A method for preparing a bromine-containing flame-retardant epoxy resin curing agent, comprising the following steps:

[0053] (1) Add 346 g of 2-bromophenol and 120 g of ethylenediamine into a reaction flask and stir to mix the materials evenly;

[0054] (2) adding 440 g of 40% acetaldehyde solution into the header tank;

[0055] (3) Add the acetaldehyde solution in the header tank to the reaction flask while controlling the temperature at 70°C.

[0056] (4) After the addition was complete, the reaction was kept at 80°C for 3 hours;

[0057] (5) After the insulation is completed, turn on the vacuum pump to remove the water generated by the reaction;

[0058] (6) cooling and filtering, and packaging to obtain the finished product of bromine-containing flame-retardant epoxy resin curing agent.

[0059] Comparative Example 1

[0060] 1. The 2-bromophenol in Example 1 was replaced with an equal molar amount of phenol to obtain a conventional bromine-free Mannich-type epoxy resin curing agent, which was prepared from the following raw materials in percentage by mass: 30% phenol, 19% ethylenediamine, and 51% formaldehyde solution (phenol, aldehyde, and amine in a molar ratio of 1:2:1).

[0061] 2. A method for preparing a conventional bromine-free Mannich-type epoxy resin curing agent, comprising the following steps:

[0062] (1) Add 188g of phenol and 120g of ethylenediamine into a reaction flask and stir to mix the materials evenly;

[0063] (2) 324 g of 37% formaldehyde solution was added to the header tank;

[0064] (3) Add the formaldehyde solution in the header tank to the reaction flask while controlling the temperature at 70°C.

[0065] (4) After the addition was complete, the reaction was kept at 80°C for 3 hours;

[0066] (5) After the insulation is completed, turn on the vacuum pump to remove the water generated by the reaction;

[0067] (6) cooling and filtering, and packaging to obtain the finished product of bromine-free epoxy resin curing agent.

[0068] Comparative Example 2

[0069] 1. Increase the amount of 2-bromophenol in Example 1 and adjust the molar ratio of phenol, aldehyde, and amine to 1.5:2:1. The product is prepared from the following raw materials in the following mass percentages: 54% 2-bromophenol, 12% ethylenediamine, and 34% formaldehyde solution.

[0070] 2. A method for preparing a bromine-containing flame-retardant epoxy resin curing agent, comprising the following steps:

[0071] (1) Add 519 g of 2-bromophenol and 120 g of ethylenediamine into a reaction flask and stir to mix the materials evenly.

[0072] (2) 324 g of 37% formaldehyde solution was added to the header tank;

[0073] (3) Add the formaldehyde solution in the header tank to the reaction flask while controlling the temperature at 70°C.

[0074] (4) After the addition was complete, the reaction was kept at 80°C for 3 hours;

[0075] (5) After the insulation is completed, turn on the vacuum pump to remove the water generated by the reaction;

[0076] (6) cooling and filtering, and packaging to obtain the finished product of bromine-containing flame-retardant epoxy resin curing agent.

[0077] Example 4 Performance Test

[0078] Epoxy resin (Model 828 epoxy resin, manufactured by Jiangsu Sanmu Chemical Co., Ltd.) was mixed with the epoxy resin curing agent prepared in Examples 1-3 and Comparative Examples 1-2 according to the calculated ratio and then evenly coated on tinplate to form a film with a thickness of 40 μm. The curing agent prepared in Comparative Example 2 had a high viscosity (30,000 mPa·s / 25°C). For ease of operation, it was diluted with 20% benzyl alcohol for application testing. The basic properties of the finished products prepared in Examples 1-3 and Comparative Examples 1-2 after curing were measured and are shown in Table 1 below.

[0079] Table 1 Performance test results

[0080]

[0081] The hardness test method in the above embodiment adopts the pencil scratch method according to the standard GB / T6739-2006; the flame retardant performance test and evaluation refer to GB / T8626.

[0082] The above performance test results show that the coating films prepared in Examples 1-3 and Comparative Examples 1-2 all have high hardness. This is because these examples are all Mannich condensation products and have a phenalkamine molecular structure. The benzene ring structure in the molecule imparts high hardness. Referring to Comparative Example 1, Examples 1-3 and Comparative Example 2 all introduce Br into their molecular structures, and they all achieve high flame retardancy. However, due to the higher viscosity of Comparative Example 2, a diluent must be added during actual application, which reduces its inherent flame retardancy.

[0083] 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 principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A bromine-containing flame-retardant epoxy resin curing agent, characterized in that: It is prepared from 2-bromophenol, polyamines and aldehydes in a molar ratio of 1:2:1; It is made of the following raw materials in the following mass percentages: 35-45% of 2-bromophenol, 10-25% of polyamine substances, and 25-50% of aldehyde substances; The preparation method of the bromine-containing flame-retardant epoxy resin curing agent comprises the following steps: (1) Add 2-bromophenol and polyamines into a reaction flask according to mass percentage and molar ratio, stir and heat to mix the materials evenly; (2) Put the measured aldehyde substances into the high-level tank; (3) Drop the aldehydes in the high-level tank into the reaction bottle; (4) After the addition is completed, continue to keep the reaction warm; (5) After the insulation is completed, turn on the vacuum pump to remove the water generated by the reaction; (6) Cooling, filtering, and packaging to obtain the finished product of bromine-containing flame-retardant epoxy resin curing agent.

2. The bromine-containing flame-retardant epoxy resin curing agent according to claim 1, characterized in that The polyamine substance is one or a mixture of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, pentanediamine, hexamethylenediamine, isophoronediamine, 1,3-cyclohexanedimethylamine, 4,4-diaminodiphenylmethane, m-xylylenediamine, cyclohexanediamine, and cyclopentanediamine.

3. The bromine-containing flame-retardant epoxy resin curing agent according to claim 1 or 2, characterized in that The aldehyde substance is one or a mixture of formaldehyde solution, acetaldehyde solution and butyraldehyde solution.

4. The method for preparing the bromine-containing flame-retardant epoxy resin curing agent according to claim 1, characterized in that: The following steps are involved: (1) Add 2-bromophenol and polyamines into a reaction flask according to mass percentage and molar ratio, stir and heat to mix the materials evenly; (2) Put the measured aldehyde substances into the high-level tank; (3) Add the aldehydes in the high-level tank to the reaction bottle while controlling the temperature at 50-70°C; (4) After the addition is complete, heat the reaction at 70-90°C for 2-4 hours; (5) After the insulation is completed, turn on the vacuum pump to remove the water generated by the reaction; (6) Cooling, filtering, and packaging to obtain the finished product of bromine-containing flame-retardant epoxy resin curing agent.

5. The method for preparing a bromine-containing flame-retardant epoxy resin curing agent according to claim 4, wherein: In the step (3), the aldehyde substance in the high-level tank is dripped into the reaction bottle, and the temperature is optimally controlled at 70°C.

6. The method for preparing a bromine-containing flame-retardant epoxy resin curing agent according to claim 4 or 5, characterized in that: The reaction temperature of step (4) is 80° C. and the reaction time is 3 hours.

7. Use of the curing agent according to any one of claims 1 to 3 as an epoxy resin curing additive.

Images