Degradable epoxy resin monomer, epoxy resin, composite material and preparation method and degradation method thereof

Abstract

The invention provides a degradable epoxy resin monomer, epoxy resin, a composite material and a preparation method and a degradation method of the degradable epoxy resin monomer, the epoxy resin and the composite material. Wherein R is selected from carbonate bonds and ester bonds; the degradable imine epoxy resin disclosed by the invention can be quickly degraded, and can solve the problems of harsh degradation conditions and slow degradation rate of the existing degradable epoxy resin.

Description

Technical Field

[0001] The invention belongs to the field of composite materials, and in particular relates to a degradable epoxy resin monomer, epoxy resin, composite material and a preparation method and a degradation method thereof. Background Art

[0002] As a functional resin material with the advantages of chemical resistance, strong adhesion, heat resistance, and electrical insulation, epoxy resin is widely used in electrical and electronic, mechanical construction, carbon fiber composites, fiberglass composites, and aerospace. Among them, in the field of carbon fiber composites and fiberglass composites, the composite material made of epoxy resin and glass fiber or carbon fiber has the characteristics of light weight, high strength and long service life. The Chinese patent document with publication number CN118546497A discloses a water-degradable epoxy resin and a preparation method thereof, using tetraethyl orthosilicate and methyldiethanolamine as raw materials, and obtaining a hyperbranched polysiloxane through a one-pot polycondensation reaction; the hyperbranched polysiloxane is mixed with an epoxy / anhydride resin system, and cured to obtain an epoxy resin that can be degraded and recovered in water. Compared with the prior art, the invention provides an epoxy resin that can be degraded and recovered in water without the presence of a traditional metal catalyst, which overcomes the defect of large pollution caused by traditional metal catalysts; at the same time, the epoxy resin has good toughness. In view of the shortcomings of the prior art, a water-degradable epoxy resin and a preparation method thereof are provided, which have the commonality of commercially available epoxy resins, are cured by acid anhydrides, can be effectively degraded and recycled in pure water, and can be used in the fields of electronic circuits, aerospace, etc. Therefore, as the requirements for product equipment in production and life gradually increase, the production demand for epoxy resins has reached an unprecedented height, while the pollution treatment of epoxy resins still remains at incineration and high-temperature pyrolysis, and the pollution problem remains severe.

[0003] As we all know, epoxy resin with a three-dimensional network cross-linked structure is infusible and difficult to reprocess and reuse like thermoplastic resin. The large amount of waste epoxy resin will cause irreversible environmental pollution, which is one of the key issues restricting the future application and development of epoxy resin composite materials. At the same time, there are high-value high-performance reinforcements in epoxy resin composite materials, and their recycling and reuse are also a key problem that the industry generally pays attention to. With the increasing attention of mankind to environmental protection and sustainable development, the degradation, recycling and reuse of epoxy resin has become a problem of widespread concern in various countries.

[0004] Therefore, it is necessary to provide an epoxy resin preparation method and a degradation and recycling method that can solve the problem that the existing degradable epoxy resin has mechanical properties far lower than those of traditional epoxy resins due to its degradable weak bonds, and at the same time solve the problems of harsh degradation conditions, slow degradation rate and recycling of the existing degradable epoxy resins. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a degradable epoxy resin monomer, epoxy resin, composite material and preparation method and degradation method thereof, aiming to solve the problem that the mechanical properties of the existing degradable epoxy resin are far lower than those of the traditional epoxy resin due to its degradable weak bonds, and at the same time solve the problems of harsh degradation conditions, slow degradation rate and recycling of the existing degradable epoxy resin.

[0006] In order to solve the above problems, the first aspect of the present invention provides a degradable epoxy resin monomer, the structural formula of which is shown in Formula 1 below; wherein R is selected from: a carbonate bond, an ester bond;

[0007]

[0008] The second aspect of the present invention provides a method for preparing a degradable epoxy resin monomer, comprising the following steps:

[0009] Bisphenol A is dissolved in a first solvent, triethylamine and allyl chloroformate are added, and then m-chloroperbenzoic acid is added to react to obtain the degradable imine epoxy resin monomer.

[0010] Preferably, the reaction temperature is 0 to 50° C., and the reaction time is 1 to 5 hours; the method further comprises filtering after the reaction is completed, separating the filtrate, and then evaporating the filtrate to obtain the degradable imine epoxy resin monomer; the solvent is water, isopentane, n-pentane, petroleum ether, hexane, cyclohexane, cyclopentane, heptane, carbon tetrachloride, benzene, toluene, xylene, chlorobenzene, o-dichlorobenzene, dichloromethane, carbon tetrachloride, methanol, ethanol, ethylene glycol, propanol, isopropanol, butanol, isobutanol, tert-butanol, amyl alcohol, benzyl alcohol, ethyl acetate, ether, petroleum ether, isopropyl ether, tetrahydrofuran, chloroform, dioxane, pyridine, acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide, or a mixture of several thereof.

[0011] The third aspect of the present invention provides a degradable epoxy resin:

[0012] The raw materials for its preparation include the degradable epoxy resin monomer as claimed in claim 1, a modified epoxy resin and a curing agent;

[0013] The mass ratio of the total mass of the degradable epoxy resin monomer and the modified epoxy resin to the curing agent is 0.1 to 10:1;

[0014] The structural formula of the degradable epoxy resin is shown in Formula 2 below:

[0015]

[0016] Preferably, the mass ratio of the degradable epoxy resin monomer to the modified epoxy resin is 1:1.

[0017] A fourth aspect of the present invention provides a method for preparing the above-mentioned degradable epoxy resin, comprising the following steps:

[0018] The degradable epoxy resin monomer, the modified epoxy resin and the curing agent are dissolved in a solvent and stirred, and then heated and cured in a mold to obtain the degradable epoxy resin.

[0019] The fifth aspect of the present invention provides a degradable epoxy resin composite material, the raw materials for preparing the composite material include:

[0020] Such as the above-mentioned degradable epoxy resin monomer, curing agent and auxiliary materials.

[0021] Preferably, the curing agent is a mixture of one or more of aliphatic amines, alicyclic amines, aromatic polyamines, polyamides, polyether amines, phenolic amines, amide amines, tertiary amines and imidazoles; the auxiliary material is a mixture of one or more of accelerators, diluents, plasticizers, toughening agents, thickeners, coupling agents, defoamers, leveling agents, ultraviolet absorbers, antioxidants, brighteners, fluorescent agents, pigments and fillers.

[0022] A sixth aspect of the present invention provides a method for degrading the above-mentioned degradable epoxy resin or degradable epoxy resin composite material, comprising:

[0023] A mixed solution of an alkaline solution and an amine solution is used as a degradation solution, and the degradable epoxy resin or the degradable epoxy resin composite material is added;

[0024] The mass concentration of the alkaline solution is 0.1-50%; the temperature during degradation is 0-200°C; and the time is 1-10 hours.

[0025] Preferably, the amine in the amine solution is one or a mixture of ethylenediamine, propylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, oleylamine, ethanolamine, diethanolamine, isopropanolamine, aniline, benzylamine, p-methylbenzylamine and N-ethylbenzylamine; the solvent in the amine solution is one or a mixture of water, isopentane, n-pentane, petroleum ether, hexane, cyclohexane, cyclopentane, heptane, carbon tetrachloride, benzene, toluene, xylene, chlorobenzene, o-dichlorobenzene, dichloromethane, carbon tetrachloride, methanol, ethanol, ethylene glycol, propanol, isopropanol, butanol, isobutanol, tert-butanol, amyl alcohol, benzyl alcohol, ethyl acetate, ether, petroleum ether, isopropyl ether, tetrahydrofuran, chloroform, dioxane, pyridine, acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide.

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

[0027] The degradable epoxy resin monomer of the present invention introduces carbonate bonds, ester bonds, etc. that can be rapidly degraded into epoxy resin through esterification reaction to prepare degradable amine-cured epoxy resin. Since the rigid ring introduced by the present invention has higher rigidity than other chemical weak bond structures, it is not easy to break under external loads, thereby making the degradable epoxy resin have mechanical properties comparable to those of traditional epoxy resins; therefore, the prepared epoxy resin can have excellent mechanical and degradation properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a characterization diagram of bisphenol A recovered after degradation from Examples 2, 3 and 4 of the present invention, and analyzed by high performance liquid chromatography. DETAILED DESCRIPTION

[0029] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0030] A first aspect of an embodiment of the present invention provides a degradable epoxy resin monomer,

[0031] Its structural formula is shown in Formula 1 below; wherein R is selected from: carbonate bond, ester bond;

[0032]

[0033] The degradable epoxy resin monomer of the embodiment of the present invention is based on the bisphenol A structure, and carbonate bonds and ester bonds are introduced. Among them, the carbonate bonds and ester bonds are weak bonds and can be degraded quickly, which can solve the problems of harsh degradation conditions and slow degradation rate of existing degradable epoxy resins; the benzene ring of bisphenol A is a rigid ring, which has higher rigidity than other chemical weak bond structures contained in epoxy resins 182, 184, etc., and is not easy to break under external loads, thereby making the degradable epoxy resin have mechanical properties comparable to traditional epoxy resins; therefore, the prepared epoxy resin can have both excellent mechanical and degradation properties.

[0034] A second aspect of an embodiment of the present invention provides a method for preparing a degradable epoxy resin monomer, comprising the following steps:

[0035] Bisphenol A is dissolved in a first solvent, triethylamine and allyl chloroformate are added, and then m-chloroperbenzoic acid is added to react to obtain the degradable imine epoxy resin monomer.

[0036] In some embodiments, the reaction temperature is 0 to 50° C., and the reaction time is 1 to 5 hours; the method further comprises filtering after the reaction is completed, separating the filtrate, and then evaporating the filtrate to obtain the degradable imine epoxy resin monomer; the solvent is water, isopentane, n-pentane, petroleum ether, hexane, cyclohexane, cyclopentane, heptane, carbon tetrachloride, benzene, toluene, xylene, chlorobenzene, o-dichlorobenzene, dichloromethane, carbon tetrachloride, methanol, ethanol, ethylene glycol, propanol, isopropanol, butanol, isobutanol, tert-butanol, amyl alcohol, benzyl alcohol, ethyl acetate, ether, petroleum ether, isopropyl ether, tetrahydrofuran, chloroform, dioxane, pyridine, acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide, or a mixture of several thereof.

[0037] A third aspect of the embodiments of the present invention provides a degradable epoxy resin:

[0038] The raw materials for its preparation include the degradable epoxy resin monomer as claimed in claim 1, a modified epoxy resin and a curing agent;

[0039] The mass ratio of the total mass of the degradable epoxy resin monomer and the modified epoxy resin to the curing agent is 0.1 to 10:1;

[0040] The structural formula of the degradable epoxy resin is shown in Formula 2 below:

[0041]

[0042] In some embodiments, the mass ratio of the degradable epoxy resin monomer to the modified epoxy resin is 1:1.

[0043] A fourth aspect of the embodiments of the present invention provides a method for preparing the above-mentioned degradable epoxy resin, comprising the following steps:

[0044] The degradable epoxy resin monomer, the modified epoxy resin and the curing agent are dissolved in a solvent and stirred, and then heated and cured in a mold to obtain the degradable epoxy resin.

[0045] A fifth aspect of the embodiments of the present invention provides a degradable epoxy resin composite material, the raw materials for preparing the composite material include:

[0046] Such as the above-mentioned degradable epoxy resin monomer, curing agent and auxiliary materials.

[0047] In some embodiments, the curing agent is a mixture of one or more of aliphatic amines, alicyclic amines, aromatic polyamines, polyamides, polyether amines, phenolic amines, amide amines, tertiary amines and imidazoles; the auxiliary material is a mixture of one or more of accelerators, diluents, plasticizers, toughening agents, thickeners, coupling agents, defoamers, leveling agents, ultraviolet absorbers, antioxidants, brighteners, fluorescent agents, pigments and fillers.

[0048] A sixth aspect of the embodiments of the present invention provides a method for degrading the above-mentioned degradable epoxy resin or degradable epoxy resin composite material, comprising:

[0049] A mixed solution of an alkaline solution and an amine solution is used as a degradation solution, and the degradable epoxy resin or the degradable epoxy resin composite material is added;

[0050] The mass concentration of the alkaline solution is 0.1-50%; the temperature during degradation is 0-200°C; and the time is 1-10 hours.

[0051] In some embodiments, the amine in the amine solution is one or a mixture of ethylenediamine, propylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, oleylamine, ethanolamine, diethanolamine, isopropanolamine, aniline, benzylamine, p-methylbenzylamine and N-ethylbenzylamine; the solvent in the amine solution is one or a mixture of water, isopentane, n-pentane, petroleum ether, hexane, cyclohexane, cyclopentane, heptane, carbon tetrachloride, benzene, toluene, xylene, chlorobenzene, o-dichlorobenzene, dichloromethane, carbon tetrachloride, methanol, ethanol, ethylene glycol, propanol, isopropanol, butanol, isobutanol, tert-butanol, amyl alcohol, benzyl alcohol, ethyl acetate, ether, petroleum ether, isopropyl ether, tetrahydrofuran, chloroform, dioxane, pyridine, acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide.

[0052] Example 1

[0053] The preparation method of the degradable imine epoxy resin of this embodiment comprises the following steps:

[0054] Dissolve 60 parts of bisphenol A in a solvent, control the temperature at 25°C under stirring, add 53 parts of triethylamine and 63 parts of allyl chloroformate dropwise, add 136 parts of m-chloroperbenzoic acid after the addition is completed, continue to react for 3 hours, filter and separate, and rotary evaporate the filtrate to obtain a degradable imine epoxy resin.

[0055] The degradable imide epoxy resin and 127 epoxy resin were mixed in a mass ratio of 8:2, and then a curing agent was added and cured at 80°C for 8 hours. The ratio of alicyclic amine curing agent to epoxy resin was 100:35. The mechanical properties and degradation properties of the cured samples were tested.

[0056] Sample curing size: bending performance sample size is 80mm*10mm*4mm; tensile performance sample size is 200mm*10mm*4mm;

[0057] The degradation method of the degradable imine epoxy resin of this embodiment comprises the following steps:

[0058] At 150°C, a mixed solution of amine and alkali is used as the degradation liquid. The amine is ethylenediamine, tetraethylenepentamine, and ethanolamine mixed in the ratio of 1:1:1. The alkali is sodium hydroxide. The solvent is water. The mass concentration of the alkali solution is 1%. The degradation temperature is 150°C. Under stirring conditions, the degradation of degradable thermosetting epoxy resin and degradable epoxy resin composites is achieved. The heating temperature is 150°C; the heating time is 3.5h. The degradation mixture is rotary evaporated and then washed with water to recover bisphenol A.

[0059] Example 2

[0060] The preparation method of the degradable imine epoxy resin of this embodiment comprises the following steps:

[0061] Dissolve 60 parts of bisphenol A in a solvent, control the temperature at 25°C under stirring, add 53 parts of triethylamine and 63 parts of allyl chloroformate dropwise, add 136 parts of m-chloroperbenzoic acid after the addition is completed, continue to react for 3 hours, filter and separate, and rotary evaporate the filtrate to obtain a degradable imine epoxy resin.

[0062] The degradable imide epoxy resin and 127 epoxy resin were mixed in a mass ratio of 6:4, a curing agent was added, and the mixture was cured at 80°C for 8 hours. The ratio of the alicyclic amine curing agent to the epoxy resin was 100:35. The mechanical properties and degradation properties of the cured samples were tested.

[0063] Sample curing size: bending performance sample size is 80mm*10mm*4mm; tensile performance sample size is 200mm*10mm*4mm;

[0064] The degradation method of the degradable imine epoxy resin of this embodiment comprises the following steps:

[0065] At 150°C, a mixed solution of amine and alkali is used as the degradation liquid. The amine is ethylenediamine, tetraethylenepentamine, and ethanolamine mixed in the ratio of 1:1:1. The alkali is sodium hydroxide. The solvent is water. The mass concentration of the alkali solution is 1%. The degradation temperature is 150°C. Under stirring conditions, the degradation of degradable thermosetting epoxy resin and degradable epoxy resin composites is achieved. The heating temperature is 150°C; the heating time is 3.5h. The degradation mixture is rotary evaporated and then washed with water to recover bisphenol A.

[0066] Example 3

[0067] The preparation method of the degradable imine epoxy resin of this embodiment comprises the following steps:

[0068] Dissolve 60 parts of bisphenol A in a solvent, control the temperature at 25°C under stirring, add 53 parts of triethylamine and 63 parts of allyl chloroformate dropwise, add 136 parts of m-chloroperbenzoic acid after the addition is completed, continue to react for 3 hours, filter and separate, and rotary evaporate the filtrate to obtain a degradable imine epoxy resin.

[0069] The degradable imide epoxy resin and 127 epoxy resin were mixed in a mass ratio of 4:6, a curing agent was added, and the mixture was cured at 80°C for 8 hours. The ratio of the alicyclic amine curing agent to the epoxy resin was 100:35. The mechanical properties and degradation properties of the cured samples were tested.

[0070] Sample curing size: bending performance sample size is 80mm*10mm*4mm; tensile performance sample size is 200mm*10mm*4mm;

[0071] The degradation method of the degradable imine epoxy resin of this embodiment comprises the following steps:

[0072] At 150°C, a mixed solution of amine and alkali is used as the degradation liquid. The amine is ethylenediamine, tetraethylenepentamine, and ethanolamine mixed in the ratio of 1:1:1. The alkali is sodium hydroxide. The solvent is water. The mass concentration of the alkali solution is 1%. The degradation temperature is 150°C. Under stirring conditions, the degradation of degradable thermosetting epoxy resin and degradable epoxy resin composites is achieved. The heating temperature is 150°C; the heating time is 3.5h. The degradation mixture is rotary evaporated and then washed with water to recover bisphenol A.

[0073] Example 4

[0074] The preparation method of the degradable imine epoxy resin of this embodiment comprises the following steps:

[0075] Dissolve 60 parts of bisphenol A in a solvent, control the temperature at 25°C under stirring, add 53 parts of triethylamine and 63 parts of allyl chloroformate dropwise, add 136 parts of m-chloroperbenzoic acid after the addition is completed, continue to react for 3 hours, filter and separate, and rotary evaporate the filtrate to obtain a degradable imine epoxy resin.

[0076] The degradable imide epoxy resin and 127 epoxy resin were mixed in a mass ratio of 2:8, alicyclic amine curing agent was added and cured at 80°C for 8 hours. The ratio of curing agent to epoxy resin was 100:35. The cured samples were subjected to mechanical property tests and degradation performance tests.

[0077] Sample curing size: bending performance sample size is 80mm*10mm*4mm; tensile performance sample size is 200mm*10mm*4mm;

[0078] The degradation method of the degradable imine epoxy resin of this embodiment comprises the following steps:

[0079] At 150°C, a mixed solution of amine and alkali is used as the degradation liquid. The amine is ethylenediamine, tetraethylenepentamine, and ethanolamine mixed in the ratio of 1:1:1. The alkali is sodium hydroxide. The solvent is water. The mass concentration of the alkali solution is 1%. The degradation temperature is 150°C. Under stirring conditions, the degradation of degradable thermosetting epoxy resin and degradable epoxy resin composites is achieved. The heating temperature is 150°C; the heating time is 3.5h. The degradation mixture is rotary evaporated and then washed with water to recover bisphenol A.

[0080] Comparative Example 1

[0081] The preparation method of the degradable imine epoxy resin of this comparative example comprises the following steps:

[0082] 127 epoxy resin and modified resin were mixed in a mass ratio of 8:2, a curing agent was added, and the mixture was cured at 80°C for 8 hours. The mechanical properties and degradation properties of the cured samples were tested.

[0083] Sample curing size: bending performance sample size is 80mm*10mm*4mm; tensile performance sample size is 200mm*10mm*4mm.

[0084] Table 1 Mechanical properties and degradation performance tests of various embodiments and comparative examples

[0085]

[0086] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A degradable epoxy resin monomer, characterized in that: Its structural formula is shown in Formula 1 below; wherein R is selected from: carbonate bond, ester bond; 2. A method for preparing a degradable epoxy resin monomer, characterized in that: The steps include: Bisphenol A is dissolved in a first solvent, triethylamine and allyl chloroformate are added, and then m-chloroperbenzoic acid is added to react to obtain the degradable imine epoxy resin monomer.

3. The method for preparing a degradable epoxy resin monomer according to claim 2, characterized in that: The reaction temperature is 0 to 50°C and the reaction time is 1 to 5 hours; The method further comprises: after the reaction is completed, filtering to separate the filtrate, and then evaporating the filtrate to obtain the degradable imine epoxy resin monomer; The solvent is one or a mixture of water, isopentane, n-pentane, petroleum ether, hexane, cyclohexane, cyclopentane, heptane, carbon tetrachloride, benzene, toluene, xylene, chlorobenzene, o-dichlorobenzene, dichloromethane, carbon tetrachloride, methanol, ethanol, ethylene glycol, propanol, isopropanol, butanol, isobutanol, tert-butanol, amyl alcohol, benzyl alcohol, ethyl acetate, ether, petroleum ether, isopropyl ether, tetrahydrofuran, chloroform, dioxane, pyridine, acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide.

4. A degradable epoxy resin, characterized in that: The raw materials for its preparation include the degradable epoxy resin monomer as claimed in claim 1, a modified epoxy resin and a curing agent; The mass ratio of the total mass of the degradable epoxy resin monomer and the modified epoxy resin to the curing agent is 0.1 to 10:1; The structural formula of the degradable epoxy resin is shown in Formula 2 below:

5. The degradable epoxy resin according to claim 4, characterized in that: The mass ratio of the degradable epoxy resin monomer to the modified epoxy resin is 1:

1.

6. A method for preparing a degradable epoxy resin as claimed in claim 4, characterized in that: The following steps are involved: The degradable epoxy resin monomer, the modified epoxy resin and the curing agent are dissolved in a solvent and stirred, and then heated and cured in a mold to obtain the degradable epoxy resin.

7. A degradable epoxy resin composite material, characterized in that: The raw materials for its preparation include: The degradable epoxy resin monomer, curing agent and auxiliary materials as claimed in claim 1.

8. The degradable epoxy resin according to claim 4 or the degradable epoxy resin composite material according to claim 7, characterized in that: The curing agent is one or a mixture of aliphatic amines, alicyclic amines, aromatic polyamines, polyamides, polyetheramines, phenolic amines, amidoamines, tertiary amines and imidazoles; The auxiliary material is one or a mixture of several of accelerator, diluent, plasticizer, toughening agent, thickener, coupling agent, defoamer, leveling agent, ultraviolet absorber, antioxidant, brightener, fluorescent agent, pigment and filler.

9. A method for degrading the degradable epoxy resin according to claim 4 or the degradable epoxy resin composite material according to claim 7, characterized in that: include: A mixed solution of an alkaline solution and an amine solution is used as a degradation solution, and the degradable epoxy resin or the degradable epoxy resin composite material is added; The mass concentration of the alkaline solution is 0.1-50%; the temperature during degradation is 0-200°C; and the time is 1-10 hours.

10. The degradation method according to claim 9, characterized in that: The amine in the amine solution is one or a mixture of ethylenediamine, propylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, oleylamine, ethanolamine, diethanolamine, isopropanolamine, aniline, benzylamine, p-methylbenzylamine and N-ethylbenzylamine; The solvent in the amine solution is one or a mixture of water, isopentane, n-pentane, petroleum ether, hexane, cyclohexane, cyclopentane, heptane, carbon tetrachloride, benzene, toluene, xylene, chlorobenzene, o-dichlorobenzene, dichloromethane, carbon tetrachloride, methanol, ethanol, ethylene glycol, propanol, isopropanol, butanol, isobutanol, tert-butanol, amyl alcohol, benzyl alcohol, ethyl acetate, ether, petroleum ether, isopropyl ether, tetrahydrofuran, chloroform, dioxane, pyridine, acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide.

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