Cashew nut shell oil modified phenolic aldehyde amine epoxy curing agent and preparation method thereof

Abstract

The invention discloses a cashew nut shell oil modified phenolic aldehyde amine epoxy curing agent and a preparation method thereof. The cashew nut shell oil modified phenolic aldehyde amine epoxy curing agent is prepared from the following components in percentage by mass: 10-20% of low-molecular fatty amine, 15-30% of formaldehyde, 35-55% of cashew nut shell oil and 15-20% of organic alcohol. Performance detection shows that the cured product has the characteristics of quick drying and high hardness, has toughness and impact resistance similar to those of a polyamide curing agent, is also suitable for low-temperature curing under a normal-temperature curing condition, is low in price and has good curing performance compared with a common phenolic aldehyde amine epoxy curing agent, and is suitable for being used in the field of high-temperature curing. The epoxy resin is mainly suitable for epoxy floor coatings, building structural adhesives and the like.

Description

Technical Field

[0001] The invention relates to a cashew nut shell oil-modified phenolic amine epoxy curing agent, belonging to the technical field of polymer materials. Background Art

[0002] The two-component system composed of epoxy resin and epoxy resin curing agent is widely used in floor coatings, anti-corrosion coatings, adhesives, composite materials and other fields due to its small curing shrinkage, adhesion, heat resistance, chemical resistance, and excellent mechanical and electrical properties.

[0003] With society's growing emphasis on environmental protection, primary polyethylene polyamine and aromatic amine curing agents have been replaced by non-toxic or low-toxic modified amines. The use of curing agents can be challenging in extreme weather conditions, such as low temperatures. Conventional curing agents often struggle to achieve the desired effect, requiring the addition of accelerators. However, excessive accelerator addition can make the cured epoxy resin brittle. Summary of the Invention

[0004] Purpose of the Invention: This invention aims to provide an epoxy curing agent with excellent workability, moderate viscosity, low-temperature curing properties, a moderate curing time, good compatibility with most curing agents and epoxy products, low toxicity, high gloss cured films, and a wide range of epoxy resin mixes, allowing customers to adjust the ratio according to specific needs. This epoxy curing agent is primarily used in primers for floor coatings, anti-corrosion coatings for building structural adhesives, and epoxy fiberglass reinforced plastics. Another object of the invention is to provide a method for preparing this epoxy curing agent.

[0005] Technical solution: To achieve the above objectives, the technical solution adopted by the present invention is:

[0006] A cashew nut shell oil-modified phenolic amine epoxy curing agent is prepared from the following raw materials in percentage by mass: 10%-20% of low-molecular fatty amine, 15-30% of formaldehyde, 35-55% of cashew nut shell oil, and 15%-20% of organic alcohols.

[0007] As a preferred embodiment, in the cashew nut shell liquid modified phenolic amine epoxy curing agent, the fatty amine is ethylenediamine or the like.

[0008] As a preferred embodiment, the cashew nut shell liquid modified phenolic amine epoxy curing agent and the formaldehyde are 37% formaldehyde solution.

[0009] The present invention provides a method for preparing a cashew nut shell liquid modified phenalkamine epoxy curing agent, which comprises the following steps:

[0010] (1) adding cashew nut shell liquid and fatty amine into a reactor according to mass percentage and stirring to mix the materials uniformly;

[0011] (2) Then, nitrogen or carbon dioxide protective gas is introduced to remove the air from the kettle and the temperature is raised to 50-60°C;

[0012] (3) Pour the measured formaldehyde solution into the high-level tank;

[0013] (4) Add the formaldehyde solution in the overhead tank to the reactor within a specified time, with the addition time being no less than 1 hour, and the temperature being controlled at 60-80°C;

[0014] (5) After the formaldehyde solution is added dropwise, the reaction is carried out at 70-80°C for 3 hours;

[0015] (6) After the heat preservation is completed, vacuum dehydration is carried out until the water is clear and transparent.

[0016] (7) After complete dehydration, cool to below 65°C, add measured methanol, and stir thoroughly to obtain a fatty amine modified epoxy curing agent.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0018] The present invention obtains the best raw material ratio composition through a large number of experimental screenings. The present invention is synthesized through the Mannich reaction according to the performance requirements of the application occasion. Because it contains phenolic hydroxyl groups, it has low-temperature curing performance.

[0019] During the experimental process, the present invention discovered that the amount of each raw material is crucial. The appropriate amount of fatty amine and long-chain cardanol can achieve excellent curing speed and flexibility. Therefore, the present invention screened through extensive experiments to obtain the optimal composition and amount ratio of each raw material.

[0020] Performance testing has shown that the epoxy curing agent prepared by this invention has excellent performance indicators such as hardness and flexibility. In addition, under room temperature curing conditions, it is also suitable for curing at temperatures around 0°C in northern China, with good curing performance. It can meet the application requirements of floor coatings and building structural adhesives, achieving very good technical results. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a reaction equation flow chart of the present invention. DETAILED DESCRIPTION

[0022] Example 1

[0023] 1. A cashew nut shell liquid modified phenolic amine epoxy curing agent, which is made from the following raw materials in percentage by mass:

[0024] 10% ethylenediamine, 55% cashew nut shell liquid, 15% formaldehyde (37% volume concentration), 20% methanol.

[0025] 2. A method for preparing a cashew nut shell liquid modified phenolic amine epoxy curing agent, comprising the following steps:

[0026] (1) Adding cashew nut shell liquid and ethylenediamine according to the above mass percentages into a reaction kettle and stirring to mix the materials evenly;

[0027] (2) Then, nitrogen protective gas is introduced to remove the air from the kettle, and the temperature is raised to 50-60°C;

[0028] (3) Pour the measured volume concentration of 37% formaldehyde solution into the high-level tank;

[0029] (4) Add the formaldehyde solution in the header tank to the reactor within a specified time, with the addition time being no less than 1 hour, and the temperature during this period being controlled at 60-80°C;

[0030] (5) After the formaldehyde solution is added dropwise, the reaction is carried out at 70-80°C for 3 hours;

[0031] (6) After the heat preservation is completed, vacuum dehydration is carried out until the water is clear and transparent.

[0032] (7) After complete dehydration, the mixture was cooled to below 65° C., and a measured amount of methanol was added and stirred for 30 minutes to obtain a cashew nut shell oil-modified phenolic amine epoxy curing agent.

[0033] Example 2

[0034] 1. A cashew nut shell liquid modified phenolic amine epoxy curing agent, which is made from the following raw materials in percentage by mass:

[0035] 15% ethylenediamine, 45% cashew nut shell liquid, 20% formaldehyde (37% volume concentration), 20% methanol.

[0036] 2. A method for preparing a fatty amine-modified epoxy curing agent, comprising the following steps:

[0037] (1) Adding cashew nut shell liquid and ethylenediamine according to the above mass percentages into a reactor and stirring to mix the materials evenly;

[0038] (2) Then, nitrogen protective gas is introduced to remove the air from the kettle, and the temperature is raised to 50-60°C;

[0039] (3) Add the measured 37% volume concentration formaldehyde solution into the high-level tank;

[0040] (4) Add the formaldehyde solution in the overhead tank to the reactor within a specified time, with the addition time being no less than 1 hour, and the temperature being controlled at 60-80°C;

[0041] (5) After the formaldehyde solution is added dropwise, the reaction is carried out at 70-80°C for 3 hours;

[0042] (6) After the heat preservation is completed, vacuum dehydration is carried out until the water is clear and transparent.

[0043] (7) After complete dehydration, the mixture was cooled to below 65° C., and a measured amount of methanol was added and stirred for 30 minutes to obtain a cashew nut shell oil-modified phenolic amine epoxy curing agent.

[0044] Example 3

[0045] 1. A cashew nut shell liquid modified phenolic amine epoxy curing agent, which is made from the following raw materials in percentage by mass:

[0046] 20% ethylenediamine, 35% cashew nut shell liquid, 30% formaldehyde (37% volume concentration), 15% methanol.

[0047] 2. A method for preparing a cashew nut shell liquid modified phenolic amine epoxy curing agent, comprising the following steps:

[0048] (1) Adding cashew nut shell liquid and ethylenediamine according to the above mass percentages into a reaction kettle and stirring to mix the materials evenly;

[0049] (2) Then, nitrogen protective gas is introduced to remove the air from the kettle, and the temperature is raised to 50-60°C;

[0050] (3) Pour the measured formaldehyde solution (37% volume concentration) into the high-level tank;

[0051] (4) Add the formaldehyde solution in the overhead tank to the reactor within a specified time, with the addition time being no less than 1 hour, and the temperature being controlled at 60-80°C;

[0052] (5) After the formaldehyde solution is added dropwise, the reaction is carried out at 70-80°C for 3 hours;

[0053] (6) After the heat preservation is completed, vacuum dehydration is carried out until the water is clear and transparent.

[0054] (7) After complete dehydration, the mixture was cooled to below 65° C., and a measured amount of methanol was added and stirred for 30 minutes to obtain a cashew nut shell oil-modified phenolic amine epoxy curing agent.

[0055] Example 4 Performance Test

[0056] According to the numbers shown in Table 1 below, epoxy resin (828 epoxy resin produced by Jiangsu Sanmu Chemical Co., Ltd.), diluent, filler, and additives were mixed with the cashew nut shell liquid-modified phenolic amine epoxy curing agent prepared in Examples 1 to 3 in the appropriate proportions to form an epoxy floor intermediate mortar layer, which was then evenly coated on top of the epoxy sealing primer. The basic properties measured after curing are shown in Table 2 below.

[0057] Table 1 Experimental formula

[0058]

[0059] Table 2 Performance test results of cashew nut shell oil modified phenolic amine epoxy curing agent examples with different formulation ratios

[0060]

[0061]

[0062] After comprehensive analysis of the three embodiments, embodiment 3 has the best comprehensive performance such as curing time and flexibility.

[0063] The curing performance of the cashew nut shell liquid modified phenolic amine epoxy curing agent prepared in Example 3 of the present invention was tested at different temperatures. The test results are shown in Table 3 below.

[0064] Table 3 Comparison of low temperature curing performance of cashew nut shell oil modified phenolic amine epoxy curing agent in Example 2

[0065] 0℃ curing, 72h performance Curing at 10℃, 72h performance Curing at 25℃, 72h performance Adhesion Level 1-2 Level 1-2 Level 1-2 flexibility 1 1 1 Hardness (Shore) 76 79 81 Impact 50 positive and negative 50 positive and negative 50 positive and negative .

[0066] The above performance test results show that the modified epoxy curing agent prepared by the present invention using different raw materials through a large number of experimental screenings has excellent performance indicators such as appearance, hardness, flexibility, etc., and a moderate curing time, which meets the application requirements of most customers and achieves very good technical results.

[0067] 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 cashew nut shell oil-modified phenolic amine epoxy curing agent, characterized in that: It is made of the following raw materials in percentage by mass: 10%-20% low molecular weight fatty amines, 15-30% formaldehyde, 35-55% cashew nut shell oil, 15%-20% organic alcohols.

2. A cashew nut shell oil modified phenolic amine epoxy curing agent according to claim 1, characterized in that: It is made of the following raw materials in percentage by mass: 10% ethylenediamine, 55% cashew nut shell oil, 15% formaldehyde, 20% organic alcohols.

3. A cashew nut shell oil modified phenolic amine epoxy curing agent according to claim 1, characterized in that: It is made of the following raw materials in percentage by mass: 15% ethylenediamine, 45% cashew nut shell oil, 20% formaldehyde, 20% organic alcohols.

4. A cashew nut shell oil modified phenolic amine epoxy curing agent according to claim 1, characterized in that: It is made of the following raw materials in percentage by mass: 20% ethylenediamine, 35% cashew nut shell oil, 30% formaldehyde, 15% organic alcohols.

5. The cashew nut shell oil modified phenolic amine epoxy curing agent according to claim 1, characterized in that: The low molecular weight aliphatic amines used include ethylenediamine.

6. The cashew nut shell oil modified phenolic amine epoxy curing agent according to claim 1, characterized in that: The formaldehyde is 37% formaldehyde solution or paraformaldehyde.

7. The cashew nut shell oil-modified phenolic amine epoxy curing agent according to claim 1, characterized in that: The organic alcohol is methanol or ethanol.

8. The method for preparing the cashew nut shell oil-modified phenolic amine epoxy curing agent according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) adding cashew nut shell liquid and low molecular weight fatty amine into a reaction kettle according to mass percentage, and stirring to make the materials mix evenly; (2) Then, nitrogen or carbon dioxide protective gas is introduced to remove the air in the kettle, and the temperature is raised to 50-60°C; (3) Pour the measured formaldehyde solution into the high-level tank; (4) dripping the formaldehyde solution in the high-level tank into the reactor within a specified time, during which the temperature is controlled at 60-80°C; (5) After the formaldehyde solution is added dropwise, the reaction is carried out at 70-80°C for 2-3 hours; (6) After the heat preservation is completed, vacuum dehydration is performed until the water is clear and transparent; (7) After complete dehydration, the mixture is cooled to below 65° C., a measured amount of organic alcohol is added, and the mixture is stirred thoroughly to obtain a cashew nut shell oil-modified phenolic amine epoxy curing agent.

9. Use of the cashew nut shell liquid modified phenolic amine epoxy curing agent according to any one of claims 1 to 7 as an epoxy resin curing agent.

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