A phenolic amine adduct and preparation method thereof

Abstract

The invention discloses a phenolic amine adduct in the technical field of epoxy curing agent preparation and a preparation method thereof. The method comprises the following steps: 1) mixing an aminophenol compound, a solvent, and a chain extender at 80-120° C. for reaction for 4-8 hours, and then adding a capping agent and mixing to obtain an intermediate; and 2) dropwise adding the intermediate to a raw amine, and reacting at 60-90° C. for 2-8 hours to obtain the phenolic amine adduct. The method aims to obtain an amine curing agent having a phenolic hydroxyl group in its structure. Compared with the phenalkamine technology based on the Mannich reaction, the method does not require the use of toxic aldehydes and ketones, nor does it require a complex dehydration process. The synthesis process is simple and efficient, and the raw material conversion rate is high. The product has the advantages of fast curing speed, low-temperature curing capability, and no oil surface whitening in a high-humidity environment as an epoxy resin curing agent. By selecting specific raw materials, a water-based product can also be prepared, and has a wide range of uses.

Description

Technical Field

[0001] The present invention relates to the technical field of epoxy resin curing agents, in particular to a phenolic amine adduct and a preparation method thereof. Background Art

[0002] Amines and their modifications are commonly used as curing agents for epoxy resins. However, both epoxy resins with amines and polyamides suffer from slow curing at low temperatures. In particular, in high-humidity environments, amine compounds are unable to react with the epoxy resin in a timely manner, instead absorbing moisture and carbon dioxide and migrating to the surface, resulting in "greasy" and "whitening" effects. To address these issues, phenols are often used as accelerators. The principle is that the phenolic hydroxyl group has a weak acidity, which binds to the more electronegative oxygen atom in the epoxy group to promote the ring opening of the epoxy group and accelerate the reaction rate. Furthermore, the phenolic hydroxyl group can undergo a reversible weak salt-forming reaction with amines, inhibiting the salt formation between the amine and carbon dioxide, while not interfering with the chemical reaction stoichiometry of the epoxy group and the active hydrogen of the amine.

[0003] To utilize phenolic hydroxyl groups in epoxy resin systems, one approach is to directly add phenolic compounds to the epoxy resin or curing agent. Small molecule phenols such as phenol, o-cresol, and salicylic acid exhibit significant crystallinity and poor compatibility with resins. Long-chain alkylphenols, such as nonylphenol, are increasingly restricted or even banned due to their reproductive toxicity and high toxicity to aquatic organisms. While styrenated phenol offers excellent overall performance, it does not participate in the crosslinking and curing reaction. Excessive use significantly reduces the crosslink density of the cured product, limiting its effectiveness. Another approach is to introduce phenolic hydroxyl groups into the structure of amines through chemical synthesis. A typical example is phenalkamine, which is obtained through the Mannich condensation reaction of phenols (such as phenol and cardanol), aldehydes (primarily formaldehyde), and polyamines. It is currently widely used in epoxy resin curing agents.

[0004] The phenolic amine structure has a high content of phenolic hydroxyl groups, reacts quickly when cured with epoxy resin, has a high cross-linking density, and has good low-temperature curing properties and excellent physical and chemical properties. However, the technical route of preparing phenolic amines by Mannich reaction has inevitable defects: phenolic amines generally use formaldehyde as a coupling agent for phenol and amine. It is well known that formaldehyde is a Class 1 carcinogen and has chronic and long-term hazards to the human body; whether formaldehyde aqueous solution or polyformaldehyde is used, formaldehyde residues and volatilization exist in the production process and the finished product, posing a threat to the health of production personnel and users; in order to remove the hazards of formaldehyde, some inventions use other coupling agents based on the Mannich reaction, such as CN201610738722.6, a Mannich base epoxy resin curing agent, which uses benzaldehyde to react with cardanol and polyamines, dehydrates and cools after the reaction, and then adds isooctanoic acid and stirs to obtain the product; CN202110490672.5 mentions a preparation method for an aldehyde-free water-based cardanol ketoneamine epoxy curing agent, which uses ketones instead of aldehydes for the Mannich reaction. According to the mechanism of the Mannich reaction, if a substituted aldehyde (benzaldehyde) or ketone is used, the reaction rate and raw material conversion rate will be greatly reduced because the steric hindrance effect is much greater than that of formaldehyde. Therefore, although the technical route of the above invention has theoretical feasibility, it lacks practical application value. A large number of small molecular aldehyde and ketone compounds remain in the system, which are also irritating and toxic. On the other hand, the Mannich reaction is a condensation reaction, and a dehydration operation must be performed to increase the conversion rate, which makes the process complicated. Summary of the Invention

[0005] In response to the deficiencies in the prior art, the present invention provides a phenolic amine adduct and a method for preparing the same, thereby resolving the risk of formaldehyde commonly used in existing phenalkamine technology and promoting the technological development of solvent-free, solvent-based and water-based epoxy curing agents.

[0006] The object of the present invention is achieved in this way: a phenolic amine adduct is prepared by comprising the following raw materials in parts by mass:

[0007] 10-40 parts of raw material amine, 10-30 parts of aminophenol, 20-50 parts of chain extender, and 10-35 parts of end-capping agent.

[0008] Furthermore, the raw material amine includes one or more of aliphatic amine, alicyclic amine, aromatic amine and polyether amine.

[0009] Furthermore, the fatty amine comprises one or more of ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, 1,4-butylenediamine, 1,5-pentanediamine, 1,6-hexanediamine, diethylenetriamine, triethylenetetramine and N,N-bis(3-aminopropyl)ethylenediamine;

[0010] The alicyclic amine comprises one or more of menthane diamine, isophorone diamine, 1,3-cyclohexane dimethylamine, methylcyclohexane diamine and 4,4-diaminodicyclohexylmethane;

[0011] The aromatic amine is 1,3-m-phenylenediamine;

[0012] The polyetheramine is selected from one or more of the trade names D230, D400, D2000 and ED2003.

[0013] Furthermore, the aminophenol comprises one or more of 3-aminophenol, p-aminophenol, p-aminophenol, o-amino-p-tert-butylphenol, 2-aminoresorcinol, and 2-amino-4-cyclohexylphenol.

[0014] Furthermore, the chain extender is selected from one or more of bisphenol A epoxy resin with an epoxy equivalent of 100 to 600 g / eq, ethylene glycol diglycidyl ether with an epoxy equivalent of 100 to 600 g / eq, polypropylene glycol diglycidyl ether with an epoxy equivalent of 200 to 800 g / eq, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,2-cyclohexanediol diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, dipropylene glycol diglycidyl ether and dimer acid diglycidyl ester.

[0015] Furthermore, the end-capping agent is selected from one or more of butyl glycidyl ether, phenyl glycidyl ether, benzyl glycidyl ether, C12-14 alkyl glycidyl ether, neodecanoic acid glycidyl ester, and cardanol glycidyl ether.

[0016] A method for preparing a phenolic amine adduct comprises the following steps:

[0017] Step 1) aminophenol and a chain extender are mixed, and the mixture is heated to a certain temperature to react to obtain an intermediate, and then a capping agent is added and mixed to obtain a dropwise solution;

[0018] Step 2) adding the dropwise addition liquid to the heated raw amine within a set time to react and keep the temperature, and obtaining a phenolic amine adduct after the temperature is maintained.

[0019] Furthermore, the specific process of the reaction in step 1) is: heating to 80-120°C and keeping warm for 4-8 hours;

[0020] The specific process of the reaction in step 2) is as follows: the temperature of the bottom liquid of the kettle is raised to 60-90°C, the temperature of the dropwise added liquid is maintained at 20-40°C, the dropwise addition is performed for 1-4 hours, and after the dropwise addition is completed, the temperature is maintained at 60-90°C for 1-4 hours to obtain a phenolic amine adduct.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention uses amino-containing phenolic compounds (aminophenols) to introduce phenolic hydroxyl groups into the chemical structure of the curing agent based on a simple and mature epoxy-amine addition reaction. There are no volatile carcinogens in the raw materials and products. The raw material conversion rate is high during the reaction, there are almost no side reactions, the process is simple and easy to produce, and the shortcomings of existing phenolic amine technology, such as health risks and complex processes, can be solved.

[0023] (2) The present invention can conveniently and flexibly adjust performance indicators such as curing speed, hardness, flexibility, and hydrophilicity by screening the raw material amine, chain extender, and end-capping agent. Therefore, based on the same process, curing agents for solvent-free or solvent-based systems can be prepared, as well as water-based curing agents;

[0024] (3) The phenolic amine adduct obtained by the present invention can be directly used as a single curing agent, or can be mixed with other amine curing agents to improve its low-temperature curing performance and other properties, and has a wide range of uses. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] Example 1

[0027] A method for preparing a phenolic amine adduct A comprises the following steps:

[0028] (1) Add 10 parts by weight of D230 polyetheramine, 5 parts by weight of ethylenediamine and 18 parts by weight of isophoronediamine into a reactor, mix well and heat to 65°C to prepare the bottom liquid;

[0029] (2) Add 9 parts by weight of 3-aminophenol and 25 parts by weight of bisphenol A epoxy resin with an epoxy equivalent of 189 to the dropping tank, mix and heat to 100°C and keep warm for 4 hours, then add 18 parts by weight of butyl glycidyl ether and 15 parts by weight of phenyl glycidyl ether, mix and cool to 30°C, and add dropwise to the bottom liquid of the kettle for 3 hours, maintaining the temperature of the material in the kettle at 65°C. After the addition is completed, the temperature of the material in the kettle is raised to 80°C and kept warm for 3 hours to obtain phenolic amine adduct A with an active hydrogen equivalent of 131g / eq.

[0030] (3) Take 41 parts by weight of phenolic amine adduct A and 59 parts by weight of bisphenol A epoxy resin with an epoxy equivalent of 189 g / eq and mix them evenly in a container. Take a small amount and use a 100 μm wire rod to make a film on a tinplate. Place it in a constant temperature and humidity chamber at 5°C and 85% humidity to cure for 24 hours and observe the appearance of the coating; the remaining mixture is divided into two parts and placed in an environment of 25°C and 5°C respectively to record the gel time.

[0031] Example 2

[0032] A method for preparing a phenolic amine adduct B comprises the following steps:

[0033] (1) Add 20 parts by weight of D400 polyetheramine and 10 parts by weight of diethylenetriamine into the reactor, mix well and heat to 70°C to prepare the bottom liquid;

[0034] (2) Add 10 parts by weight of p-aminophenol, 28 parts by weight of bisphenol A epoxy resin with an epoxy equivalent of 189 g / eq, and 17 parts by weight of polypropylene glycol diglycidyl ether with an epoxy equivalent of 300 g / eq into a dropping tank, mix, heat to 100°C, and keep warm for 4 hours. Then add 15 parts by weight of o-cresol glycidyl ether, mix, cool to 30°C, and dropwise add to the bottom liquid of the kettle for 3 hours, maintaining the temperature of the material in the kettle at 70°C. After the dropwise addition is completed, the temperature of the material in the kettle is raised to 80°C and kept warm for 3 hours to obtain phenolic amine adduct B with an active hydrogen equivalent of 173 g / eq.

[0035] (3) Take 48 parts by weight of phenolic amine adduct B and 52 parts by weight of bisphenol A epoxy resin with an epoxy equivalent of 189 g / eq and mix them evenly in a container. Take a small amount and use a 100 μm wire rod to make a film on a tinplate. Place it in a constant temperature and humidity chamber at 5°C and 85% humidity to cure for 24 hours and observe the appearance of the coating; the remaining mixed liquid is divided into two parts and placed in an environment of 25°C and 5°C respectively to record the gel time.

[0036] Example 3

[0037] A method for preparing a phenolic amine adduct C comprises the following steps:

[0038] (1) Add 17 parts by weight of isophorone diamine and 10 parts by weight of diethylenetriamine into a reaction kettle, mix well, and then heat to 70°C to prepare the bottom liquid;

[0039] (2) Add 15 parts by weight of p-aminophenol and 33 parts by weight of bisphenol A epoxy resin with an epoxy equivalent of 189 g / eq to a dropping tank, then heat to 120°C and keep warm for 4 hours. Then add 25 parts by weight of C12-14 alkyl glycidyl ether, cool to 30°C, and dropwise add to the bottom liquid of the kettle for 3 hours, maintaining the temperature of the material in the kettle at 70°C. After the addition is completed, the temperature of the material in the kettle is raised to 80°C and kept warm for 3 hours to obtain phenolic amine adduct C with an active hydrogen equivalent of 133 g / eq.

[0040] (3) Take 41 parts by weight of phenolic amine adduct C and 59 parts by weight of bisphenol A epoxy resin with an epoxy equivalent of 189 g / eq and mix them evenly in a container. Take a small amount and use a 100 μm wire rod to make a film on a tinplate. Place it in a constant temperature and humidity chamber at 5°C and 85% humidity to cure for 24 hours and observe the appearance of the coating; the remaining mixed liquid is divided into two parts and placed in an environment of 25°C and 5°C respectively to record the gel time.

[0041] Example 4

[0042] A method for preparing a phenolic amine adduct D comprises the following steps:

[0043] (1) Add 20 parts by weight of D2000 polyetheramine and 18 parts by weight of diethylenetriamine into a reactor, mix well, and then heat to 70°C to prepare the bottom liquid;

[0044] (2) Add 14 parts by weight of o-amino-p-tert-butylphenol and 32 parts by weight of bisphenol A epoxy resin with an epoxy equivalent of 189 g / eq to a dropping tank, then heat to 120°C and keep warm for 4 hours. Then add 16 parts by weight of phenyl glycidyl ether, mix, cool to 30°C, and dropwise add to the bottom liquid of the kettle for 3 hours, maintaining the temperature of the material in the kettle at 70°C. After the dropwise addition is completed, the temperature of the material in the kettle is raised to 80°C and kept warm for 3 hours to obtain phenolic amine adduct D with an active hydrogen equivalent of 123 g / eq.

[0045] (3) Take 39 parts by weight of phenolic amine adduct D and 61 parts by weight of bisphenol A epoxy resin with an epoxy equivalent of 189 g / eq and mix them evenly in a container. Take a small amount and use a 100 μm wire rod to make a film on a tinplate. Place it in a constant temperature and humidity chamber at 5°C and 85% humidity to cure for 24 hours and observe the appearance of the coating; the remaining mixture is divided into two parts and placed in an environment of 25°C and 5°C respectively to record the gel time.

[0046] Example 5

[0047] A method for preparing a phenolic amine adduct E comprises the following steps:

[0048] (1) Add 18 parts by weight of 1,6-hexanediamine and 4 parts by weight of diethylenetriamine into a reaction kettle, mix well, and then heat to 60°C to prepare the bottom liquid;

[0049] (2) Add 16 parts by weight of 2-aminoresorcinol, 30 parts by weight of bisphenol A epoxy resin with an epoxy equivalent of 189 g / eq, and 20 parts by weight of polyethylene glycol diglycidyl ether with an epoxy equivalent of 280 g / eq into a dropping tank, heat the mixture to 120°C and keep it warm for 4 hours, then add 12 parts by weight of C12-14 alkyl glycidyl ether, cool the mixture to 30°C, and drop it into the bottom liquid of the kettle for 3 hours, maintaining the temperature of the material in the kettle at 60°C. After the addition is completed, raise the temperature of the material in the kettle to 80°C and keep it warm for 3 hours to obtain phenolic amine adduct E with an active hydrogen equivalent of 120 g / eq.

[0050] (3) Take 39 parts by weight of phenolic amine adduct E and 61 parts by weight of bisphenol A epoxy resin with an epoxy equivalent of 189 g / eq and mix them evenly in a container. Take a small amount and use a 100 μm wire rod to make a film on a tinplate. Place it in a constant temperature and humidity chamber at 5°C and 85% humidity to cure for 24 hours and observe the appearance of the coating; the remaining mixture is divided into two parts, placed in an environment of 25°C and 5°C respectively, and the gel time is recorded.

[0051] Example 6

[0052] A method for preparing a phenolic amine adduct F comprises the following steps:

[0053] (1) Add 12 parts by weight of D400 polyetheramine and 20 parts by weight of isophorone diamine into a reactor, mix well, and then heat to 70°C to prepare the bottom liquid;

[0054] (2) Add 19 parts by weight of 2-amino-4-cyclohexylphenol, 22 parts by weight of bisphenol A epoxy resin with an epoxy equivalent of 189 g / eq, and 12 parts by weight of polyethylene glycol diglycidyl ether with an epoxy equivalent of 280 g / eq into a dropping tank, heat the mixture to 120°C and keep it warm for 4 hours, then add 15 parts by weight of phenyl glycidyl ether, cool the mixture to 30°C, and drop it into the bottom liquid of the kettle for 3 hours, maintaining the temperature of the material in the kettle at 60°C. After the addition is completed, raise the temperature of the material in the kettle to 80°C and keep it warm for 3 hours to obtain a phenolic amine adduct F with an active hydrogen equivalent of 181 g / eq.

[0055] (3) Take 49 parts by weight of phenolic amine adduct F and 51 parts by weight of bisphenol A epoxy resin with an epoxy equivalent of 189 g / eq and mix them evenly in a container. Take a small amount and use a 100 μm wire rod to make a film on a tinplate. Place it in a constant temperature and humidity chamber at 5°C and 85% humidity to cure for 24 hours and observe the appearance of the coating; the remaining mixture is divided into two parts, placed in an environment of 25°C and 5°C respectively, and the gel time is recorded.

[0056] Comparative Example 1

[0057] Take 34 parts by weight of a commercially available epoxy resin-added amine curing agent with an active hydrogen equivalent of 93 g / eq and 66 parts by weight of a bisphenol A epoxy resin with an epoxy equivalent of 189 g / eq and mix them evenly in a container. Take a small amount and use a 100 μm wire rod to form a film on a tinplate. Place it in a constant temperature and humidity chamber at 5°C and 85% humidity to cure for 24 hours, and observe the appearance of the coating; the remaining mixed liquid is divided into two parts, placed in an environment of 25°C and 5°C respectively, and the gel time is recorded.

[0058] Comparative Example 2

[0059] Take 33 parts by weight of a commercially available polyamide curing agent with an active hydrogen equivalent of 93 g / eq and 67 parts by weight of a bisphenol A epoxy resin with an epoxy equivalent of 189 g / eq and mix them evenly in a container. Take a small amount and use a 100 μm wire rod to form a film on a tinplate. Place it in a constant temperature and humidity chamber at 5°C and 85% humidity to cure for 24 hours and observe the appearance of the coating; the remaining mixed liquid is divided into two parts, placed in an environment of 25°C and 5°C respectively, and the gel time is recorded.

[0060] Comparative Example 3

[0061] Take 33 parts by weight of a commercially available phenolic amine curing agent with an active hydrogen equivalent of 95 g / eq and 67 parts by weight of a bisphenol A epoxy resin with an epoxy equivalent of 189 g / eq and mix them evenly in a container. Take a small amount and use a 100 μm wire rod to form a film on a tinplate. Place it in a constant temperature and humidity chamber at 5°C and 85% humidity to cure for 24 hours, and observe the appearance of the coating; the remaining mixture is divided into two parts, and placed in an environment of 25°C and 5°C respectively to record the gel time.

[0062] The present invention does not use formaldehyde and does not require complex processes such as dehydration, is easy to produce on a large scale, and better meets the industry's needs for rapid curing, low-temperature curing, and construction in high-humidity environments. By using an amino-containing phenolic compound (aminophenol), phenolic hydroxyl groups can be introduced into the chemical structure of the curing agent based on a simple and mature epoxy-amine addition reaction. By screening the raw material amine, chain extender, and end-capping agent, performance indicators such as curing speed, hardness, flexibility, and hydrophilicity can be conveniently and flexibly adjusted. The raw material conversion rate is high during the reaction, there are almost no side reactions, the process is simple and easy to produce, and the risk of formaldehyde being commonly used in existing phenalkamine technology can be resolved. This has a driving effect on the technical development of solvent-free, solvent-based, and water-based epoxy curing agents.

[0063] 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.

[0064] The performance tests described in the above examples and comparative examples include the gel time of the curing agent and epoxy resin mixture at different temperatures, and the appearance of the coating in a low temperature and high humidity environment after film formation. The test results are shown in Table 1:

[0065] Table 1: Curing properties of phenolic amine adducts

[0066]

[0067] As shown in Table 1, the phenolic amine adduct obtained by the present invention, when used in combination with a standard liquid epoxy resin, exhibits room temperature curing speed, low-temperature curing performance, and performance in high-humidity and low-temperature environments comparable to or even superior to commercially available phenalkamine curing agents, and significantly outperforms non-phenol-modified addition amines and polyamides. Therefore, the present invention can completely replace formaldehyde-based phenalkamine products in terms of application performance, while significantly surpassing existing phenalkamine technologies in terms of environmental friendliness and ease of production.

[0068] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a phenolic amine adduct, wherein the phenolic amine adduct is prepared from the following raw materials in parts by weight: 10-40 parts of raw material amine, 10-30 parts of aminophenol, 20-50 parts of chain extender, 10-35 parts of end-capping agent; The raw material amine comprises one or more of aliphatic amine, alicyclic amine, aromatic amine and polyether amine; The fatty amine comprises one or more of ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, 1,4-butylenediamine, 1,5-pentanediamine, 1,6-hexanediamine, diethylenetriamine, triethylenetetramine and N,N-bis(3-aminopropyl)ethylenediamine; The alicyclic amine comprises one or more of menthane diamine, isophorone diamine, 1,3-cyclohexane dimethylamine, methylcyclohexane diamine and 4,4-diaminodicyclohexylmethane; The aromatic amine is 1,3-m-phenylenediamine; The polyetheramine is selected from one or more of the trade names D230, D400, D2000 and ED2003; The aminophenol comprises one or more of 3-aminophenol, p-aminophenol, p-aminophenol, o-amino-p-tert-butylphenol, 2-aminoresorcinol, and 2-amino-4-cyclohexylphenol; The chain extender is selected from one or more of bisphenol A epoxy resin with an epoxy equivalent of 100 to 600 g / eq, ethylene glycol diglycidyl ether with an epoxy equivalent of 100 to 600 g / eq, polypropylene glycol diglycidyl ether with an epoxy equivalent of 200 to 800 g / eq, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,2-cyclohexanediol diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, dipropylene glycol diglycidyl ether and dimer acid diglycidyl ester; The end-capping agent is selected from one or more of butyl glycidyl ether, phenyl glycidyl ether, benzyl glycidyl ether, C12-14 alkyl glycidyl ether, neodecanoic acid glycidyl ester, and cardanol glycidyl ether; It is characterized in that The following steps are involved: Step 1) aminophenol and a chain extender are mixed, and the mixture is heated to a certain temperature to react to obtain an intermediate, and then a capping agent is added and mixed to obtain a dropwise solution; Step 2) adding the dropwise addition liquid to the heated raw amine within a set time to react and keep the temperature, and obtaining a phenolic amine adduct after the temperature is maintained.

2. The method for preparing a phenolic amine adduct according to claim 1, wherein: The specific process of the reaction in step 1) is: heating to 80-120°C and keeping warm for 4-8 hours; The specific process of the reaction in step 2) is as follows: the temperature of the bottom liquid of the kettle is raised to 60-90°C, the temperature of the dropwise added liquid is maintained at 20-40°C, the dropwise addition is performed for 1-4 hours, and after the dropwise addition is completed, the temperature is maintained at 60-90°C for 1-4 hours to obtain a phenolic amine adduct.

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