Imidazole Mannich base epoxy resin curing agent with good damp-heat resistance and acid resistance as well as preparation method and application of imidazole Mannich base epoxy resin curing agent

Abstract

The invention discloses an imidazole Mannich base epoxy resin curing agent with good damp-heat resistance and acid resistance and a preparation method thereof. The imidazole Mannich base epoxy resin curing agent is prepared from 25-65% of an imidazole substance, 5-35% of an aldehyde substance and 20-60% of a polyamine substance. Performance detection shows that the product is high in curing speed, high in mechanical strength and good in humidity and heat resistance, particularly compared with a traditional phenol Mannich base epoxy resin curing agent, the humidity and heat resistance and the acid resistance are obviously improved, the epoxy resin curing agent is suitable for corrosion prevention of steel pipes of oil gas mines, natural gas transportation and the like, and a very good technical effect is achieved.

Description

Technical Field

[0001] The invention relates to an epoxy resin curing agent, in particular to an imidazo Mannich base epoxy resin curing agent with fast curing speed, high mechanical strength, good moisture and heat resistance and acid resistance and a preparation method, belonging to the technical field of polymer materials. Background Art

[0002] Acidizing is a commonly used measure to improve oil well recovery in oil fields, but the injection of acid will cause serious corrosion to the pipeline, and the dissolved Fe 3+ Entering the formation will cause permanent damage to the formation, resulting in great economic losses and environmental pollution. In industrial applications, the commonly used protection methods for related pipelines are: coating, electroplating, hot-dip galvanizing, cathodic protection and adding corrosion inhibitors.

[0003] Using coatings to protect metals is the simplest and most effective method. Among them, epoxy resin coatings are widely used in anti-corrosion coatings due to their excellent adhesion and excellent chemical resistance. However, for metals that are in acidic media for a long time, ordinary epoxy anti-corrosion coatings are difficult to achieve long-term high-quality protection, mainly because the performance of epoxy curing agents is limited.

[0004] The present invention starts from the molecular structure design, integrates the structural characteristics of epoxy curing agent and organic corrosion inhibitor, and obtains an imidazole Mannich base epoxy curing agent through the Mannich reaction of imidazole substances, aldehyde substances and polyamine substances. The imidazole structure in the curing agent provides good rigidity, heat resistance and acid resistance, and the tertiary amine structure has the effect of promoting curing, so the product has fast curing speed, high mechanical strength, good moisture and heat resistance, and in particular, compared with the traditional phenol Mannich base epoxy resin curing agent, the acid resistance is significantly improved, and it is suitable for the corrosion protection of steel pipes such as oil and gas mines and natural gas transportation. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide an epoxy resin curing agent with fast curing speed, high mechanical strength, good moisture and heat resistance and acid resistance to meet the anti-corrosion needs of steel pipes in oil and gas mines, natural gas transportation, etc.; another purpose of the present invention is to provide a method for preparing the epoxy resin curing agent.

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

[0007] An imidazole Mannich base epoxy resin curing agent with good moisture resistance, heat resistance and acid resistance is prepared from the following raw materials in percentage by mass: 25-65% of imidazole substances, 5-35% of aldehyde substances and 20-60% of polyamine substances.

[0008] As a preferred embodiment, the above-mentioned imidazole Mannich base epoxy resin curing agent with good moisture and heat resistance and acid resistance, the imidazole substance is one or a mixture of imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, benzimidazole.

[0009] As a preferred embodiment, in the above-mentioned imidazole Mannich base epoxy resin curing agent with good moisture and heat resistance and acid resistance, the aldehyde substance is one or a mixture of formaldehyde, acetaldehyde, n-butyraldehyde, benzaldehyde, and cinnamaldehyde.

[0010] As a preferred embodiment, the above-mentioned imidazolinium Mannich base epoxy resin curing agent with good moisture and heat resistance and acid resistance, the polyamine substance is one or a mixture of several of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, pentamethylenediamine, hexamethylenediamine, 2-methylpentamethylenediamine, isophoronediamine, 1,3-cyclohexyldimethylamine, meta-xylylenediamine, cyclohexyldiamine, cyclopentamethylenediamine, diaminodicyclohexylmethane, and diaminodiphenylmethane.

[0011] The preparation method of the imidazole Mannich base epoxy resin curing agent with good moisture and heat resistance and acid resistance of the present invention comprises the following steps:

[0012] (1) adding imidazole substances and polyamine substances according to mass percentage into a reactor, stirring to mix the materials evenly, and heating to 50-60° C.;

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

[0014] (3) adding the aldehyde substances in the high-level tank into the reactor in batches, during which the temperature is controlled at 50-80°C;

[0015] (4) After the aldehyde material is added, the temperature is raised to 80-100° C. and kept for reaction for 2-4 hours;

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

[0017] (6) After the water is completely removed, the mixture is cooled and filtered, and then packaged to obtain the finished product: an imidazole Mannich base epoxy resin curing agent having good resistance to moisture, heat and acid.

[0018] The present invention mainly improves the deficiencies of the prior art through the following solutions:

[0019] 1. The product of the present invention has a novel structure. No epoxy curing agent with this structure has been reported. The novel structure gives it unique properties.

[0020] 2. The conventional Mannich base epoxy curing agent adopts the Mannich reaction of phenol, aldehyde and amine. The present invention replaces phenol with imidazole substances. The imidazole ring has a considerable rigidity with the benzene ring. Meanwhile, the tertiary amine on the imidazole ring has a stronger ability to promote the curing speed than the hydroxyl group of phenol. Therefore, the imidazole Mannich base epoxy curing agent has a faster curing speed.

[0021] 3. The imidazole Mannich base obtained by the Mannich reaction of imidazole substances, aldehydes and amines has the effect of slowing down acid corrosion. Therefore, the imidazole Mannich base epoxy curing agent has better acid resistance than the traditional Mannich base epoxy curing agent.

[0022] 4. The present invention can achieve diversity in product molecular structure through raw material selection, thereby designing products suitable for different usage requirements.

[0023] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0024] The present invention designs a novel epoxy curing agent, which obtains an imidazole Mannich base by a Mannich reaction of imidazole substances, aldehydes and amines, and has the following advantages: 1. The imidazole group is introduced, and the curing agent has a fast curing speed and excellent mechanical strength; 2. The imidazole Mannich base structure has a corrosion inhibition effect. After the curing agent is matched with epoxy resin, the paint film dries quickly, has excellent mechanical strength and resistance to moisture, heat and acid, and is suitable for the anti-corrosion of steel pipes such as oil and gas mines and natural gas transportation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the reaction equation of Example 1 of the present invention. DETAILED DESCRIPTION

[0026] Example 1

[0027] 1. An imidazole Mannich base epoxy resin curing agent with good moisture resistance, heat resistance and acid resistance is made of the following raw materials in percentage by mass: 57% benzimidazole, 14% formaldehyde and 29% ethylenediamine.

[0028] 2. A method for preparing an imidazole Mannich base epoxy resin curing agent having good moisture and heat resistance and acid resistance, comprising the following steps:

[0029] (1) 570 g of benzimidazole and 290 g of ethylenediamine were added to a reactor, stirred to mix the materials evenly, and heated to 50-60° C.;

[0030] (2) Add 140 g of formaldehyde into the high-level tank;

[0031] (3) Adding formaldehyde from the header tank into the reactor in batches, during which the temperature is controlled at 70-80°C;

[0032] (4) After the formaldehyde is added, the temperature is raised to 90-100°C and kept for reaction for 4 hours;

[0033] (5) After the insulation is completed, turn on the vacuum pump to remove the water generated by the reaction;

[0034] (6) After the water is completely removed, the mixture is cooled, filtered, and packaged to obtain the finished product.

[0035] Example 2

[0036] 1. An imidazole Mannich base epoxy resin curing agent with good moisture resistance, heat resistance and acid resistance is made of the following raw materials in percentage by mass: 45% benzimidazole, 11% formaldehyde and 44% hexamethylenediamine.

[0037] 2. A method for preparing an imidazole Mannich base epoxy resin curing agent having good moisture and heat resistance and acid resistance, comprising the following steps:

[0038] (1) Add 450 g of benzimidazole and 440 g of hexamethylenediamine into a reactor, stir to mix the materials evenly, and heat to 50-60° C.;

[0039] (2) Add 110 g of formaldehyde into the high-level tank;

[0040] (3) Adding formaldehyde from the header tank into the reactor in batches, during which the temperature is controlled at 70-80°C;

[0041] (4) After the formaldehyde is added, the temperature is raised to 90-100°C and kept for reaction for 4 hours;

[0042] (5) After the insulation is completed, turn on the vacuum pump to remove the water generated by the reaction;

[0043] (6) After the water is completely removed, the mixture is cooled, filtered, and packaged to obtain the finished product.

[0044] Example 3

[0045] 1. An imidazole Mannich base epoxy resin curing agent with good moisture resistance, heat resistance and acid resistance is made of the following raw materials in percentage by mass: 42% benzimidazole, 10% formaldehyde and 48% m-xylylenediamine.

[0046] 2. A method for preparing an imidazole Mannich base epoxy resin curing agent having good moisture and heat resistance and acid resistance, comprising the following steps:

[0047] (1) 420 g of benzimidazole and 480 g of m-xylylenediamine were added to a reactor, stirred to mix the materials evenly, and heated to 50-60° C.;

[0048] (2) Add 100 g of formaldehyde into the high-level tank;

[0049] (3) Adding formaldehyde from the header tank into the reactor in batches, during which the temperature is controlled at 70-80°C;

[0050] (4) After the formaldehyde is added, the temperature is raised to 90-100°C and kept for reaction for 4 hours;

[0051] (5) After the insulation is completed, turn on the vacuum pump to remove the water generated by the reaction;

[0052] (6) After the water is completely removed, the mixture is cooled, filtered, and packaged to obtain the finished product.

[0053] Example 4

[0054] 1. An imidazole Mannich base epoxy resin curing agent with good moisture resistance, heat resistance and acid resistance is made of the following raw materials in percentage by mass: 33% benzimidazole, 29% benzaldehyde and 38% m-xylylenediamine.

[0055] 2. A method for preparing an imidazole Mannich base epoxy resin curing agent having good moisture and heat resistance and acid resistance, comprising the following steps:

[0056] (1) 330 g of benzimidazole and 380 g of m-xylylenediamine were added to a reactor, stirred to mix the materials evenly, and heated to 50-60° C.;

[0057] (2) 290 g of benzaldehyde was added to the header tank;

[0058] (3) adding benzaldehyde from the header tank into the reactor in batches, during which the temperature is controlled at 70-80° C.;

[0059] (4) After the benzaldehyde is added, the temperature is raised to 90-100° C. and kept for reaction for 4 hours;

[0060] (5) After the insulation is completed, turn on the vacuum pump to remove the water generated by the reaction;

[0061] (6) After the water is completely removed, the mixture is cooled, filtered, and packaged to obtain the finished product.

[0062] Example 5

[0063] 1. An imidazole Mannich base epoxy resin curing agent with good moisture resistance, heat resistance and acid resistance is made of the following raw materials in percentage by mass: 48% of 2-methylimidazole, 17% of formaldehyde and 35% of ethylenediamine.

[0064] 2. A method for preparing an imidazole Mannich base epoxy resin curing agent having good moisture and heat resistance and acid resistance, comprising the following steps:

[0065] (1) 480 g of 2-methylimidazole and 350 g of ethylenediamine were added to a reactor, stirred to mix the materials evenly, and heated to 50-60° C.;

[0066] (2) Add 170 g of formaldehyde into the high-level tank;

[0067] (3) Adding formaldehyde from the header tank into the reactor in batches, during which the temperature is controlled at 70-80°C;

[0068] (4) After the formaldehyde is added, the temperature is raised to 90-100°C and kept for reaction for 4 hours;

[0069] (5) After the insulation is completed, turn on the vacuum pump to remove the water generated by the reaction;

[0070] (6) After the water is completely removed, the mixture is cooled, filtered, and packaged to obtain the finished product.

[0071] Example 6 Comparative Example

[0072] 1. In Example 1, the benzimidazole is replaced by an equal molar amount of phenol, which is prepared from the following raw materials in percentage by mass: 51% phenol, 16% formaldehyde, and 33% ethylenediamine.

[0073] 2. A method for preparing a phenol Mannich base epoxy resin curing agent, comprising the following steps:

[0074] (1) 510 g of phenol and 330 g of ethylenediamine were added to a reactor, stirred to mix the materials evenly, and heated to 50-60° C.;

[0075] (2) Add 160 g of formaldehyde into the high-level tank;

[0076] (3) Adding formaldehyde from the header tank into the reactor in batches, during which the temperature is controlled at 70-80°C;

[0077] (4) After the formaldehyde is added, the temperature is raised to 90-100°C and kept for reaction for 4 hours;

[0078] (5) After the insulation is completed, turn on the vacuum pump to remove the water generated by the reaction;

[0079] (6) After the water is completely removed, the mixture is cooled, filtered, and packaged to obtain the finished product.

[0080] Example 7 Performance Test

[0081] Epoxy resin (828 produced by Jiangsu Sanmu Chemical Co., Ltd.) was mixed evenly with the epoxy resin curing agent prepared in Examples 1-6, and evenly coated on the tinplate to form a film with a film thickness of 40 μm. The basic properties of the finished product after curing were measured as shown in the following table.

[0082]

[0083]

[0084] .

[0085] The above performance test results show that, by selecting imidazoles, aldehydes and polyamines, curing agents with different properties can be designed, wherein the heat and moisture resistance and acid resistance of embodiments 3 and 4 are better, and the flexibility of embodiments 1 and 2 is better, so that they can be applied to different occasions. Compared with the traditional phenol-type Mannich base epoxy curing agent (embodiment 6), the imidazole Mannich base epoxy curing agent has similar mechanical properties, but the acid resistance of the coating has been greatly improved, making it suitable for corrosion protection under acidic conditions, such as corrosion protection of steel pipes such as oil and gas mines and natural gas transportation, and has achieved very good technical effects.

[0086] 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 principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An imidazole Mannich base epoxy resin curing agent with good heat and moisture resistance and acid resistance, characterized in that: The invention is prepared from the following raw materials in the following mass percentages: 25-65% of imidazole substances, 5-35% of aldehyde substances and 20-60% of polyamine substances.

2. An imidazole Mannich base epoxy resin curing agent with good heat and moisture resistance and acid resistance, characterized in that: The invention is prepared from the following raw materials in percentage by mass: 57% of benzimidazole, 14% of formaldehyde and 29% of ethylenediamine.

3. An imidazole Mannich base epoxy resin curing agent with good heat and moisture resistance and acid resistance, characterized in that: 45% benzimidazole, 11% formaldehyde, 44% hexamethylenediamine.

4. An imidazole Mannich base epoxy resin curing agent with good heat and moisture resistance and acid resistance, characterized in that: 42% benzimidazole, 10% formaldehyde, 48% m-xylylenediamine.

5. The imidazole Mannich base epoxy resin curing agent with good heat and moisture resistance and acid resistance according to claim 1, characterized in that: The imidazole substance is one or a mixture of imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole and benzimidazole.

6. The imidazole Mannich base epoxy resin curing agent with good heat and moisture resistance and acid resistance according to claim 1, characterized in that: The aldehyde substance is one or a mixture of formaldehyde, acetaldehyde, n-butyraldehyde, benzaldehyde and cinnamaldehyde.

7. The imidazole Mannich base epoxy resin curing agent with good heat and moisture resistance and acid resistance according to claim 1, characterized in that: The polyamine substance is one or a mixture of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, pentanediamine, hexanediamine, 2-methylpentanediamine, isophoronediamine, 1,3-cyclohexanedimethylamine, meta-xylylenediamine, cyclohexanediamine, cyclopentanediamine, diaminodicyclohexylmethane, and diaminodiphenylmethane.

8. The method for preparing the imidazole Mannich base epoxy resin curing agent with good moisture and heat resistance and acid resistance according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) adding imidazole substances and polyamine substances according to mass percentage into a reactor, stirring to mix the materials evenly, and heating to 40-60° C.; (2) adding the measured aldehyde substances into the high-level tank; (3) adding the aldehyde substances in the high-level tank into the reactor in batches, during which the temperature is controlled at 50-80°C; (4) After the aldehyde material is added, the temperature is raised to 70-100° C. for reaction; (5) After the insulation is completed, turn on the vacuum pump to remove the water generated by the reaction; (6) After the water is completely removed, the mixture is cooled and filtered, and packaged to obtain an imidazole Mannich base epoxy resin curing agent having good heat and moisture resistance and acid resistance.

9. The method for preparing the imidazole Mannich base epoxy resin curing agent with good moisture and heat resistance and acid resistance according to claim 8, characterized in that: The following steps are involved: (1) adding imidazole substances and polyamine substances according to mass percentage into a reactor, stirring to mix the materials evenly, and heating to 50-60° C.; (2) adding the measured aldehyde substances into the high-level tank; (3) adding the aldehyde substances in the high-level tank into the reactor in batches, during which the temperature is controlled at 50-80°C; (4) After the aldehyde material is added, the temperature is raised to 80-100° C. and kept for reaction for 2-4 hours; (5) After the insulation is completed, turn on the vacuum pump to remove the water generated by the reaction; (6) After the water is completely removed, the mixture is cooled and filtered, and packaged to obtain an imidazole Mannich base epoxy resin curing agent having good heat and moisture resistance and acid resistance.

10. Use of the imidazolin-Mannich base epoxy resin curing agent with good moisture resistance, heat resistance and acid resistance as claimed in any one of claims 1 to 8 as an epoxy resin curing agent in anti-corrosion coatings for oil and gas mines and natural gas transportation steel pipes.

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