CN116102501A - Three-functionality modified imidazole curing agent and preparation method and application thereof - Google Patents

Three-functionality modified imidazole curing agent and preparation method and application thereof Download PDF

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CN116102501A
CN116102501A CN202310199590.4A CN202310199590A CN116102501A CN 116102501 A CN116102501 A CN 116102501A CN 202310199590 A CN202310199590 A CN 202310199590A CN 116102501 A CN116102501 A CN 116102501A
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curing agent
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modified imidazole
imidazole curing
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陈恩宇
任华
谢涛
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Zhejiang University ZJU
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
    • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
    • C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
    • C08G59/50—Amines
    • C08G59/5046—Amines heterocyclic
    • C08G59/5053—Amines heterocyclic containing only nitrogen as a heteroatom
    • C08G59/5073—Amines heterocyclic containing only nitrogen as a heteroatom having two nitrogen atoms in the ring
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D233/00—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings
    • C07D233/54—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members
    • C07D233/56—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members with only hydrogen atoms or radicals containing only hydrogen and carbon atoms, attached to ring carbon atoms
    • C07D233/60—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members with only hydrogen atoms or radicals containing only hydrogen and carbon atoms, attached to ring carbon atoms with hydrocarbon radicals, substituted by oxygen or sulfur atoms, attached to ring nitrogen atoms
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    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D163/00—Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/03—Powdery paints
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2150/00—Compositions for coatings
    • C08G2150/20—Compositions for powder coatings

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Abstract

The invention relates to the technical field of epoxy resin curing agents, and provides a trifunctional modified imidazole curing agent, a preparation method and application thereof. According to the invention, benzene ring groups with good compatibility with epoxy resin are introduced into the modified imidazole curing agent structure, and meanwhile, the functionality of the curing agent is increased, so that the curing degree of the epoxy resin is improved, and the mechanical properties of a cured product are improved. The trifunctional modified imidazole curing agent provided by the invention has low curing temperature and high hardness of a cured product, and has very important application significance in the field of low-temperature curing of epoxy powder coatings. The invention also provides a preparation method of the trifunctional modified imidazole curing agent, which adopts the glycidyl ether with the triphenol methane structure and the common imidazole curing agent as main raw materials to prepare the trifunctional modified imidazole curing agent, has low cost and simple flow, and is suitable for industrial production.

Description

Three-functionality modified imidazole curing agent and preparation method and application thereof
Technical Field
The invention relates to the technical field of epoxy resin curing agents, in particular to a trifunctional modified imidazole curing agent, a preparation method and application thereof.
Background
The powder coating is a powder coating containing a solid resin as a main component, wherein the solid resin is usually an epoxy resin. The epoxy resin contains epoxy groups with higher activity, can react with substances containing more active hydrogen to cause ring-opening curing, and the cured epoxy resin coating has better mechanical properties and can be used for protecting a substrate. The conventional epoxy resin curing temperature is generally 180-200 ℃, and the high curing temperature makes the epoxy resin only applicable to heat-resistant substrates, so that the use of the epoxy resin on heat-sensitive substrates is limited.
The imidazole curing agent is a low-temperature curing agent of epoxy resin with higher curing activity, and can be cured completely at the temperature of 90-120 ℃ generally, but the mixed resin system of the imidazole curing agent is easy to be cured and deteriorated at normal temperature due to the excessive activity of the imidazole curing agent. At present, the imidazole curing agent is modified to reduce the activity, but the imidazole curing agent is limited to use in liquid resin. Therefore, the development of the modified imidazole suitable for the solid epoxy resin system has very important significance and application value.
The introduction of electron withdrawing groups and macromolecular groups by ring opening addition of secondary amines on imidazoles to epoxy groups on epoxy resins is a good modification method and such groups typically include benzene rings, cyano groups, and the like. The introduction of the above groups reduces the activity of the imidazole itself by reducing the electron cloud density on the imidazole and creating a steric effect. However, the introduction of the above groups may result in excessive reduction of imidazole activity and poor compatibility of the curing agent with the epoxy resin to thereby result in incomplete curing, and the mechanical properties of the resulting cured product may be reduced.
Accordingly, there is a need to provide a curing agent which is suitable for solid epoxy resins and which can improve the mechanical properties of the cured product.
Disclosure of Invention
In view of the above, the invention provides a trifunctional modified imidazole curing agent, and a preparation method and application thereof. The trifunctional modified imidazole curing agent provided by the invention is suitable for solid epoxy resin, and has low curing temperature and high mechanical strength of cured products.
In order to achieve the above object, the present invention provides the following technical solutions:
a trifunctional modified imidazole curing agent having the structure of formula I:
Figure BDA0004109444950000021
in formula I: r is R 1 Methyl, ethyl or phenyl; r is R 2 Is H or methyl.
Preferably, the molecular weight of the trifunctional modified imidazole curing agent is 706.84-892.39 g/mol.
The invention also provides a preparation method of the trifunctional modified imidazole curing agent, which comprises the following steps:
mixing 4,4' -trihydroxy trimethylbenzene, tetrabutylammonium bromide and epichlorohydrin for substitution reaction, mixing the obtained substitution reaction liquid with sodium hydroxide solution for ring closure reaction to obtain trifunctional glycidyl ether with a structure shown as formula II;
Figure BDA0004109444950000022
mixing the trifunctional glycidyl ether, the imidazole compound and the solvent for ring-opening reaction to obtain the trifunctional modified imidazole curing agent; the structure of the imidazole compound is shown in a formula III;
Figure BDA0004109444950000023
preferably, the mass ratio of the 4,4' -trihydroxy trimethylbenzene to the tetrabutylammonium bromide is 8-10:1-5;
the mass ratio of the 4,4' -trihydroxy trimethylbenzene to the epichlorohydrin is 8-10:85-92.
Preferably, the temperature of the substitution reaction is 85-120 ℃ and the time is 2-3.5 h.
Preferably, the mass ratio of the 4,4' -trihydroxy trimethylbenzene to the sodium hydroxide solution is 7-7.5:10-11; the concentration of the sodium hydroxide solution was 30wt%.
Preferably, the temperature of the ring-closure reaction is 40-44 ℃ and the time is 1.5-2 h.
Preferably, the mass ratio of the trifunctional glycidyl ether to the imidazole compound is 11-19:10-11; the mass ratio of the trifunctional glycidyl ether to the solvent is 14-27:10-11.
Preferably, the temperature of the ring-opening reaction is 100-120 ℃ and the time is 0.5-1 h.
The invention also provides an application of the trifunctional modified imidazole curing agent in the epoxy powder coating.
The invention provides a trifunctional modified imidazole curing agent, which has a structure shown in a formula I. The modified imidazole curing agent provided by the invention contains a rigid benzene ring structure in a molecular structure, has good compatibility with bisphenol A epoxy resin, and simultaneously provides a large number of rigid structures with better mechanical properties for cured samples; the invention also increases the functionality of the modified imidazole curing agent, and the structure of the three functional groups in the curing process is beneficial to improving the crosslinking density of the system and the content of the rigid structure, so that the curing degree of the epoxy resin can be improved, the mechanical property of the cured product is improved, the curing temperature is low, and the modified imidazole curing agent has very important significance in the field of low-temperature curing of the epoxy powder coating and has wide application prospect. The results of the examples show that the trifunctional modified imidazole curing agent provided by the invention is used for curing solid epoxy resin, the curing temperature is about 140 ℃, the curing agent has good low-temperature curing performance, the pencil hardness of the surface of the cured product can reach 3-4H, and the cured product has good mechanical properties.
The invention also provides a preparation method of the trifunctional modified imidazole curing agent, which adopts the glycidyl ether with the triphenol methane structure and the common imidazole curing agent as main raw materials to prepare the trifunctional modified imidazole curing agent, has low cost and simple flow, is easy to separate products after the reaction is finished, and is suitable for industrial production.
Drawings
FIG. 1 is a nuclear magnetic resonance spectrum of a trifunctional modified imidazole curing agent prepared in example 1 of the present invention.
Detailed Description
The invention provides a trifunctional modified imidazole curing agent, which has a structure shown in a formula I:
Figure BDA0004109444950000041
in formula I: r is R 1 Methyl, ethyl or phenyl; r is R 2 Is H or methyl.
In the present invention, when R 1 R is methyl or phenyl 2 Preferably H, when R 1 When ethyl, R 2 Preferably methyl.
The trifunctional modified imidazole curing agent provided by the invention has a structure similar to bisphenol A epoxy resin, has good compatibility, and imidazole connected to the glycidyl ether end group can be cured and crosslinked with the epoxy resin to form a polymer network, so that the obtained cured product has the characteristics of high hardness and low curing temperature, and can be used in surface coatings of some heat-sensitive substrates.
In the invention, the molecular weight of the trifunctional modified imidazole curing agent is 706.84-892.39 g/mol.
The invention also provides a preparation method of the trifunctional modified imidazole curing agent, which comprises the following steps:
mixing 4,4' -trihydroxy trimethylbenzene, tetrabutylammonium bromide and epichlorohydrin for substitution reaction, mixing the obtained substitution reaction liquid with sodium hydroxide solution for ring closure reaction to obtain trifunctional glycidyl ether with a structure shown as formula II;
Figure BDA0004109444950000042
mixing the trifunctional glycidyl ether, the imidazole compound and the solvent for ring-opening reaction to obtain the trifunctional modified imidazole curing agent; the structure of the imidazole compound is shown in a formula III;
Figure BDA0004109444950000051
in the invention, the synthetic route of the trifunctional modified imidazole curing agent is shown as a formula IV
Figure BDA0004109444950000052
The following describes the preparation method of the trifunctional modified imidazole curing agent in the present invention in detail.
The invention mixes 4,4' -trihydroxy trimethylbenzene, tetrabutylammonium bromide (TBAB) and epoxy chloropropane to carry out substitution reaction, and mixes the obtained substitution reaction liquid and sodium hydroxide solution to carry out ring closure reaction to obtain trifunctional glycidyl ether. In the invention, the mass ratio of the 4,4' -trihydroxy trimethylbenzene to the tetrabutylammonium bromide is preferably 8-10:1-5, more preferably 8.5-9.5:2-4; the mass ratio of the 4,4' -trihydroxy trimethylbenzene to the epichlorohydrin is preferably 8-10:85-92, more preferably 8.5-9.5:88-90.
In the present invention, the temperature of the substitution reaction is preferably 85 to 120 ℃, more preferably 90 to 110 ℃, and the time of the substitution reaction is preferably 2 to 3.5 hours, more preferably 2.5 to 3 hours.
In the invention, the mass ratio of the 4,4' -trihydroxy trimethylbenzene to the sodium hydroxide in the sodium hydroxide solution is preferably 7-7.5:10-11; the concentration of the sodium hydroxide solution is preferably 30wt%; the temperature of the ring closure reaction is preferably 40-44 ℃ and the time is preferably 1.5-2 h. After the substitution reaction is finished, the obtained ring-opening reaction liquid is cooled to 40-44 ℃, and then sodium hydroxide solution is slowly dripped into the system; the dropwise addition time of the sodium hydroxide solution is preferably 0.5 to 1 hour.
After the ring closure reaction is finished, the method preferably comprises the steps of cooling the obtained product liquid, filtering, washing the obtained filtrate, and performing reduced pressure distillation to obtain the trifunctional glycidyl ether; the invention removes sodium chloride generated in the reaction process by filtration, and removes unreacted epichlorohydrin and residual detergent by reduced pressure distillation; the washing detergent is preferably hot water or acetone, and the temperature of the hot water is preferably 80-90 ℃.
After the trifunctional glycidyl ether is obtained, the trifunctional glycidyl ether, the imidazole compound and the solvent are mixed for ring-opening reaction, and the trifunctional modified imidazole curing agent with the structure shown in the formula I is obtained. In the invention, the imidazole compound has a structure shown in a formula III, wherein R in the formula III 1 And R is 2 The species of (2) are the same as those in formula I, and are not described in detail herein; in a specific embodiment of the present invention, the imidazole compound is preferably one of 2-methylimidazole, 2-ethyl-4-methylimidazole and 2-phenylimidazole; the mass ratio of the trifunctional glycidyl ether to the imidazole compound is preferably 11-19:10-11, more preferably 12-18:10-11; the mass ratio of the trifunctional glycidyl ether to the solvent is preferably 14-27:10-11, more preferably 15-26:10-11; the solvent is preferably a benzene-based solvent, more preferably one or both of toluene and xylene. In the present invention, the temperature of the ring-opening reaction is preferably 100 to 120 ℃, more preferably 110 to 120 ℃, and the time of the ring-opening reaction is preferably 0.5 to 1h, more preferably 0.6 to 0.8h.
In the specific embodiment of the invention, the imidazole compound and the solvent are preferably mixed firstly, the mixture is stirred for 1h after being heated to 100-120 ℃ so that the imidazole compound is completely dissolved, and then the trifunctional glycidyl ether is dropwise added into the system; the dripping time of the trifunctional glycidyl ether is preferably 0.5-1 h; the time of the ring-opening reaction is counted from the completion of the addition of the trifunctional glycidyl ether.
After the ring-opening reaction is finished, the invention preferably pours out the upper liquid in the product feed liquid, and the residual product is dried after rotary evaporation to obtain the trifunctional modified imidazole curing agent with the structure shown in the formula I; in the invention, the drying temperature is preferably 80-90 ℃, and the drying time is preferably 5-8 h; the drying is preferably carried out in a vacuum environment; the invention removes the residual solvent on the surface of the product by drying.
The invention also provides an application of the trifunctional modified imidazole curing agent in the epoxy powder coating. In the invention, the trifunctional modified imidazole curing agent is specifically used as a curing agent of solid epoxy resin in an epoxy powder coating, wherein the solid epoxy resin is preferably bisphenol A type epoxy resin, more preferably E12 solid epoxy resin; the mass ratio of the trifunctional modified imidazole curing agent to the solid epoxy resin is preferably 0.15-5:100, more preferably 1.5-5:100; in the specific embodiment of the invention, the trifunctional modified imidazole curing agent and the solid epoxy resin are preferably mixed, melted and extruded, and the obtained mixture is sprayed on the surface of a substrate under the melting condition, and a solid coating is formed after curing; the curing temperature is preferably 138-142 ℃, more preferably 140 ℃, and the curing time is preferably 15-20 min; the substrate is preferably a heat-sensitive substrate.
The following description of the embodiments of the present invention will clearly and fully describe the technical solutions of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
29.2g of 4,4' -trihydroxybenzoyl methane, 3.4g of tetrabutylammonium bromide and 294g of epichlorohydrin were placed in a three-necked flask equipped with a reflux condenser and a thermometer, and the temperature was slowly raised to a liquid temperature in the flask to 85 ℃. The temperature was maintained for 3 hours and the temperature was reduced to 44 ℃ when the liquid in the flask turned from rose to yellow. 13.2g of NaOH was dissolved in 30.8g of deionized water, and the solution was slowly added dropwise, and the reaction was continued at the reaction temperature for 1.5 hours after the completion of the addition for 0.5 hours. After the reaction, naCl generated in the system is removed by cooling and precipitation. Adding deionized water at 80-90 ℃ into the yellow liquid product, cleaning for 3-4 times, and distilling under reduced pressure to remove epoxy chloropropane which is not completely reacted and redundant water to obtain the yellow product, namely the trifunctional glycidyl ether.
16.524g of 2-ethyl-4-methylimidazole and 10.62g of xylene were mixed and charged into a round bottom flask equipped with a reflux condenser, and the temperature was raised to 120℃and stirred for 1 hour until the imidazole was completely dissolved. 23.02g of the yellow product was slowly added and the dropwise addition was completed within 0.5 h. Keeping the temperature of the oil bath at 120 ℃ for continuous reaction for 0.5h, pouring out the upper solvent, removing the solvent from the lower product by rotary evaporation, and then drying in a vacuum oven at 85 ℃ for 6h until the lower product is completely dried to obtain an orange-yellow solid product, namely the trifunctional modified imidazole curing agent with the structure shown in formula I, wherein R is as follows 1 Is ethyl, R 2 Is methyl. The nuclear magnetic hydrogen spectrum of the product is shown in figure 1.
The mixture was obtained by mixing, melting and extruding 5.25g of the modified imidazole hardener and 350g of E12 solid epoxy resin. The mixture was cured at a constant temperature of 140℃by DSC, and the curing temperature was relatively low. The mixture is sprayed on a metal substrate, the surface of the coating after being melted and solidified for 15min is well leveled, the forward impact height of the solidified product is 50cm, the product is cracked after the forward impact height is 50cm, and the pencil hardness is 3H.
Example 2
14.6g of 4,4' -trihydroxy triphenylmethane, 1.7g of tetrabutylammonium bromide and 147g of epichlorohydrin are added into a three-necked flask provided with a reflux condenser and a thermometer, the temperature is slowly increased to heat the liquid in the three-necked flask to 115 ℃, the reflux reaction is kept for 2 hours, the liquid in the flask is changed from rose to orange yellow, and the temperature is reduced to 44 ℃. 6.6g of NaOH is dissolved in 15.4g of deionized water, slowly added dropwise to the solution, and the reaction temperature is maintained for further 1.5h after the addition of 0.5 h. After the reaction is finished, cooling, precipitating and separating to remove NaCl generated in the system, adding 15mL of acetone to clean the yellow liquid product for 3-4 times, and distilling under reduced pressure to remove unreacted completely epichlorohydrin and residual acetone to obtain the yellow product, namely the trifunctional glycidyl ether.
7.39g of 2-methylImidazole and 5.31g of xylene were mixed and added to a round bottom flask equipped with a reflux condenser, and the mixture was stirred for 1h at 120℃until imidazole was completely dissolved. 13.82g of the yellow product was slowly added and the dropwise addition was completed within 0.5 h. Keeping the temperature of the oil bath at 120 ℃ for continuous reaction for 0.5h, pouring out the upper solvent, rotationally steaming the lower product to remove the solvent, grinding, drying in a vacuum 90 ℃ oven for 3h until the lower product is completely dried to obtain a brown yellow solid product, namely the trifunctional modified imidazole curing agent with the structure shown in the formula I, wherein R is as follows 1 Is methyl, R 2 H. The nuclear magnetic hydrogen spectrum characteristic displacement of the product is 7.08,6.91,5.44,3.75-4.22 and 2.54ppm.
The mixture is obtained by mixing, melting and extruding 5g of the modified imidazole curing agent and 100g of E12 solid epoxy resin. The mixture was cured at a constant temperature of 140℃by DSC, and the curing temperature was relatively low. The mixture is sprayed on a metal substrate, the surface of the coating after being melted and solidified for 15min is well leveled, the forward impact height of the solidified product is 45cm and the back impact height is 35cm, and the pencil hardness is 4H.
Example 3
14.6g of 4,4' -trihydroxy triphenylmethane, 1.7g of tetrabutylammonium bromide and 147g of epichlorohydrin are added into a three-necked flask provided with a reflux condenser and a thermometer, the temperature is slowly increased to heat the liquid in the three-necked flask to 115 ℃, the reflux reaction is kept for 2 hours, the liquid in the flask is changed from rose to orange yellow, and the temperature is reduced to 44 ℃. 6.6g of NaOH is dissolved in 15.4g of deionized water, slowly added dropwise to the solution, and the reaction temperature is maintained for further 1.5h after the addition of 0.5 h. After the reaction is finished, cooling, precipitating and separating to remove NaCl generated in the system, adding deionized water at 90 ℃ to clean the yellow liquid product for 3-4 times, and distilling under reduced pressure to remove the epoxy chloropropane which is not completely reacted and the residual deionized water, thereby obtaining the yellow product, namely the trifunctional glycidyl ether.
8.77g of 2-phenylimidazoline and 6.37g of xylene were mixed and introduced into a round-bottomed flask equipped with a reflux condenser, heated to 120℃and stirred for 1h until the imidazole was completely dissolved. 9.22g of the yellow product was slowly added and the dropwise addition was completed within 0.5 h. Keeping the temperature of the oil bath at 110 DEG CReacting for 0.25h, pouring out the upper solvent, steaming the lower product to remove the solvent, grinding, drying in a vacuum 90 ℃ oven for 3h to completely dry to obtain a brown yellow solid product, namely the trifunctional modified imidazole curing agent with the structure shown in formula I, wherein R is 1 Is phenyl, R 2 H. The nuclear magnetic hydrogen spectrum characteristic displacement of the product is 7.49,7.68,6.95,6.85,3.75-4.25 and 3.35ppm.
The mixture was obtained by mixing, melting and extruding 7.5g of the modified imidazole hardener and 150g of E12 solid epoxy resin. The mixture is sprayed on a metal substrate, the surface of the coating after being melted and solidified for 15min at 140 ℃ is well leveled, the forward impact height of the solidified product is 35cm and the recoil height is 20cm, and the pencil hardness is 3H.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims (10)

1. The trifunctional modified imidazole curing agent is characterized by having a structure shown in a formula I:
Figure FDA0004109444930000011
in formula I: r is R 1 Methyl, ethyl or phenyl; r is R 2 Is H or methyl.
2. The trifunctional modified imidazole curing agent according to claim 1, wherein the trifunctional modified imidazole curing agent has a molecular weight of 706.84-892.39 g/mol.
3. The method for preparing the trifunctional modified imidazole curing agent according to claim 1 or 2, which is characterized by comprising the following steps:
mixing 4,4' -trihydroxy trimethylbenzene, tetrabutylammonium bromide and epichlorohydrin for substitution reaction, mixing the obtained substitution reaction liquid with sodium hydroxide solution for ring closure reaction to obtain trifunctional glycidyl ether with a structure shown as formula II;
Figure FDA0004109444930000012
mixing the trifunctional glycidyl ether, the imidazole compound and the solvent for ring-opening reaction to obtain the trifunctional modified imidazole curing agent; the structure of the imidazole compound is shown in a formula III;
Figure FDA0004109444930000013
4. the preparation method according to claim 3, wherein the mass ratio of the 4,4' -trihydroxybutylene to tetrabutylammonium bromide is 8-10:1-5;
the mass ratio of the 4,4' -trihydroxy trimethylbenzene to the epichlorohydrin is 8-10:85-92.
5. The method according to claim 3 or 4, wherein the temperature of the substitution reaction is 85 to 120 ℃ for 2 to 3.5 hours.
6. A method according to claim 3, characterized in that the mass ratio of the 4,4',4 "-trimethylbenzene trihydroxide to the sodium hydroxide solution is 7-7.5:10-11 and the concentration of the sodium hydroxide solution is 30wt%.
7. The method according to claim 3 or 6, wherein the temperature of the ring-closure reaction is 40 to 44 ℃ for 1.5 to 2 hours.
8. The preparation method according to claim 3, wherein the mass ratio of the trifunctional glycidyl ether to the imidazole compound is 11-19:10-11; the mass ratio of the trifunctional glycidyl ether to the solvent is 14-27:10-11.
9. The method according to claim 3, wherein the ring-opening reaction is carried out at a temperature of 100 to 120℃for a period of 0.5 to 1 hour.
10. Use of the trifunctional modified imidazole hardener according to claim 1 or 2 or prepared by the preparation method according to any one of claims 3 to 9 in epoxy powder coatings.
CN202310199590.4A 2023-02-27 2023-02-27 Three-functionality modified imidazole curing agent and preparation method and application thereof Pending CN116102501A (en)

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