Epoxy resin nonionic emulsifier, method for preparing same, and water-based epoxy emulsion

Abstract

The application provides an epoxy resin nonionic emulsifier, a preparation method thereof and a water-based epoxy emulsion, and is prepared by the following method: an organic silane containing a hydrolysable functional group and dextran are sequentially added into a water-methanol mixed solvent, the pH value of the mixed solution is adjusted to 3-5 by using an organic acid, stirring is carried out at 35-60 DEG C for 0.5-4 h until the mixed solution is clear and transparent; then, a catalyst, boron trifluoride ether aqueous solution, is slowly added dropwise, and reaction is carried out at 40-60 DEG C for 2-6 h, lye is added dropwise until the pH value is neutral, and after recovery of the solvent, the organic silicon modified polysaccharide epoxy resin nonionic emulsifier OP is obtained. The emulsion prepared by the application has good hydrophobic performance on the surface, improves the water resistance and corrosion resistance of the water-based epoxy emulsion cured film, and simultaneously, under the synergistic toughening effect of the carboxylated dextran and the organic silicon, the tensile strength and flexibility of the water-based epoxy emulsion cured film are significantly improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of epoxy emulsion, and particularly relates to an epoxy resin nonionic emulsifier, a preparation method thereof and a water-based epoxy emulsion. BACKGROUND

[0002] The water-based epoxy emulsion has excellent bonding performance, electrical insulation and corrosion resistance, and is prepared by using water as a dispersion medium, so it has small viscosity, is easy to use and clean, is green and environmentally friendly, and has attracted extensive attention. Common methods for preparing the water-based epoxy emulsion include a mechanical method (direct emulsification method), a chemical modification method, a phase inversion method and a curing agent emulsification method. The phase inversion method is to disperse the epoxy resin into small droplets under the action of high-speed shearing, and slowly add water in the process, so that the mixed system is changed from water-in-oil into oil-in-water, phase inversion occurs, and the water-based epoxy emulsion is obtained.

[0003] The emulsifier is a key factor affecting the performance of the water-based epoxy emulsion prepared by the phase inversion method. The epoxy resin emulsifier can be divided into three types of cationic, anionic and nonionic types according to the chemical structure, and the nonionic emulsifier is most widely used. The existing technology generally introduces polyethylene glycol with different molecular weights into the epoxy resin to obtain the nonionic emulsifier by a chemical synthesis method. Since the polyethylene glycol molecular chain segment is a hydrophilic group, the prepared water-based epoxy emulsion has slow room temperature curing speed, and the water resistance and corrosion resistance of the cured film are seriously affected, thereby affecting the comprehensive performance and application effect of the water-based epoxy emulsion. SUMMARY

[0004] In view of the problems in the prior art, the first object of the present application is to provide an epoxy resin nonionic emulsifier and a preparation method thereof, and the second object is to provide a water-based epoxy emulsion. The water resistance, wear resistance and toughness are improved.

[0005] The first object is achieved by the following technical scheme: a preparation method of an epoxy resin nonionic emulsifier, characterized by the following method: an organic silane containing a hydrolysable functional group and carboxylated dextran are sequentially added into a water-methanol mixed solvent, an organic acid is used to adjust the pH value of the mixed solution to 3-5, stirring is performed at 35-60 DEG C for 0.5-4 h until the mixed solution is clear and transparent; then a catalyst, boron trifluoride ether aqueous solution, is slowly added dropwise, and reaction is performed at 40-60 DEG C for 2-6 h, an alkali solution is added dropwise until the pH value is neutral, and after recovery of the solvent, the organic silicon modified polysaccharide epoxy resin nonionic emulsifier OP is obtained.

[0006] The structural formula of the bisphenol A epoxy resin is:

[0007]

[0008] The structural formula of the carboxylated dextran is:

[0009] In the above scheme, the structure of the organic silane containing hydrolysable functional group is: R n SiX 4-n wherein X is a monovalent hydrolysable functional group, Si-X can be hydrolyzed into Si-OH; R is an alkyl group, and n is 1-3.

[0010] In the above scheme, X is halogen or alkoxy.

[0011] In the above scheme, the organic silane containing hydrolysable functional group is one of propyl trimethoxysilane, propyl triethoxysilane, dimethyl diethoxysilane, trimethyl ethoxysilane, propyl dimethyl chlorosilane, dimethyl dichlorosilane, and propyl trichlorosilane.

[0012] In the above scheme, the molar ratio of the organic silane containing hydrolysable functional group to the carboxylated dextran is 1:1-3, the volume ratio in the water-methanol mixed solvent is 1:3, the mass of boron trifluoride ether is 0.1%-5% of the mass of the organic silane, and the average molecular weight of the carboxylated dextran is 4000-9000 Da.

[0013] In the above scheme, the lye is a sodium hydroxide solution or a potassium hydroxide solution.

[0014] A preparation method of the epoxy resin non-ionic emulsifier, and the epoxy resin non-ionic emulsifier OP prepared by the method.

[0015] The second object of the present application is achieved in that an aqueous epoxy emulsion is characterized in that it is prepared by mixing OP with bisphenol A epoxy resin, heating in a water bath at 50-60°C, high-speed dispersion, and slowly adding water until the viscosity of the system suddenly decreases and the system changes from water-in-oil to oil-in-water, adjusting the solid content of the aqueous epoxy emulsion by adding water (in the examples of the present application, the solid content is adjusted to 50±0.5%, and the solid content can be adjusted according to requirements), and continuing high-speed dispersion for 0.5-1 h to obtain a non-ionic aqueous epoxy emulsion.

[0016] In the above scheme, the addition amount of OP is 20-35 parts by mass, and the bisphenol A epoxy resin is 100 parts, and the bisphenol A epoxy resin is at least one of epoxy E44 and epoxy E51.

[0017] In the above scheme, the dispersion is carried out at 2000-4000 r / min.

[0018] The present application utilizes the organic silane containing hydrolysable functional group to hydrolyze into epoxy silanol under weak acidic condition, and reacts with the carboxyl in carboxylated dextran to form silicate under the action of catalyst, i.e. organic silicon modified polysaccharide nonionic emulsifier, and then uses phase inversion method to emulsify bisphenol A epoxy resin, i.e. waterborne epoxy emulsion. The preparation principle is that the organic silane hydrolyzes into silanol with alkyl chain under weak acidic condition, and the carboxylated dextran is modified by introducing carboxyl into dextran, and has the characteristics of dextran molecule, and the carboxyl reacts with the silicon hydroxyl in the hydrolysis product of the organic silane to form organic silicon modified polysaccharide nonionic emulsifier, and the waterborne epoxy emulsion is prepared by using phase inversion method to emulsify bisphenol A epoxy resin.

[0019] The molecular structure characteristics of the organic silicon modified polysaccharide nonionic emulsifier are that it contains organic silicon hydrophobic group and carboxylated dextran nonionic surface active at the same time, wherein the organic silicon hydrophobic group can improve the room temperature curing speed of the waterborne epoxy emulsion, and endows the cured film with better hydrophobic property, thereby improving the water resistance and corrosion resistance, and can also improve the toughness of the cured film of the waterborne epoxy emulsion; the carboxylated dextran with average molecular weight of 4000-9000 Da is selected in the present application, and the hydrophilicity and mechanical property are considered, on the one hand, the polyhydroxy in the carboxyl dextran enhances the hydrophilicity of the epoxy resin, and the waterborne epoxy resin can be obtained, on the other hand, the long chain polyring in the introduced carboxyl dextran enhances the toughness of the cured film of the waterborne epoxy emulsion. DETAILED DESCRIPTION

[0020] The present application will be further described below in combination with examples.

[0021] Example 1

[0022] The total mass of 60 g of propyl trimethoxysilane (C3H7Si(OCH3)3) and carboxylated dextran with average molecular weight of 4000 Da is sequentially added into 120 ml of water-methanol (the volume ratio of water to methanol is 1:3) mixed solvent, wherein the molar ratio of propyl trimethoxysilane to 4000 Da carboxylated dextran is 1:3; the pH value of the mixed solution is adjusted to about 4 by using acetic acid, and stirring is carried out at 45℃ for 2 h until the mixed solution is clear and transparent; then the catalyst aqueous solution of boron trifluoride ether is slowly added dropwise, the mass of boron trifluoride ether is 0.5% of the mass of propyl trimethoxysilane, and reaction is carried out at 50℃ for 3 h, and the aqueous solution of NaOH is added dropwise until the pH value is neutral, and after recovering the solvent, the organic silicon modified polysaccharide nonionic emulsifier OP1 is obtained.

[0023] Mix 20 parts of the polysaccharide emulsifier OP1 prepared in the previous step and 100 parts of epoxy resin E51, heat in a water bath at 50°C, disperse at a high speed of 2500 r / min, and slowly add water dropwise until the viscosity of the system suddenly decreases from water-in-oil to oil-in-water, add water to a total amount of 120 parts, adjust the solid content of the waterborne epoxy emulsion to 50±0.5%, and continue to disperse at a high speed of 2500 r / min for 0.5 h to obtain a non-ionic waterborne epoxy emulsion WE1.

[0024] Example 2

[0025] Add 60 g of total mass of propyl triethoxysilane (C3H7Si(OC2H5)3) and carboxylated dextran with an average molecular weight of 4000 Da into 120 ml of a mixed solvent of water-methanol (water to methanol in a volume ratio of 1:3) in sequence, wherein the molar ratio of propyl triethoxysilane to 4000 Da carboxylated dextran is 1:3; adjust the pH value of the mixed solution to 3 with acetic acid, stir at 50°C for 2 h until the mixed solution is clear and transparent; then slowly add a catalyst of aqueous boron trifluoride ether solution, the mass of boron trifluoride ether is 1.0% of the mass of propyl triethoxysilane, and react at 55°C for 4 h, add aqueous KOH solution until the pH value is neutral, and after recovering the solvent, obtain the non-ionic polysaccharide emulsifier OP2 modified by organosilicon.

[0026] Mix 20 parts of the polysaccharide emulsifier OP2 prepared in the previous step and 100 parts of epoxy resin E44, heat in a water bath at 55°C, disperse at a high speed of 3000 r / min, and slowly add water dropwise until the viscosity of the system suddenly decreases from water-in-oil to oil-in-water, add water to a total amount of 120 parts, continue to disperse at a high speed of 3000 r / min for 0.5 h to obtain a non-ionic waterborne epoxy emulsion WE2.

[0027] Example 3

[0028] Add 60 g of total mass of dimethyl diethoxysilane ((CH3)2Si(OC2H5)2) and carboxylated dextran with an average molecular weight of 4000 Da into 120 ml of a mixed solvent of water-methanol (water to methanol in a volume ratio of 1:3) in sequence, wherein the molar ratio of dimethyl diethoxysilane to 4000 Da carboxylated dextran is 1:2; adjust the pH value of the mixed solution to 5 with acetic acid, stir at 55°C for 2 h until the mixed solution is clear and transparent; then slowly add a catalyst of aqueous boron trifluoride ether solution, the mass of boron trifluoride ether is 0.8% of the mass of dimethyl diethoxysilane, and react at 55°C for 4 h, add aqueous KOH solution until the pH value is neutral, and after recovering the solvent, obtain the non-ionic polysaccharide emulsifier OP3 modified by organosilicon.

[0029] Mix 25 parts of the polysaccharide emulsifier OP3 prepared in the previous step, 50 parts of the epoxy resin E44 and 50 parts of the epoxy resin E51, heat in a water bath at 55°C, disperse at a high speed of 3000 r / min, and slowly add water dropwise until the viscosity of the system suddenly decreases from water-in-oil to oil-in-water, add water to a total amount of 125 parts, and continue to disperse at a high speed of 2500 r / min for 1 h. After recovering the solvent, a non-ionic waterborne epoxy emulsion WE3 is obtained.

[0030] Example 4

[0031] Add 60 g of trimethylethoxysilane ((CH3)3SiOC2H5) and carboxylated dextran with an average molecular weight of 5000 Da into 120 ml of a mixed solvent of water-methanol (water to methanol in a volume ratio of 1:3) in sequence, wherein the molar ratio of trimethylethoxysilane to carboxylated dextran with 5000 Da is 1:1; adjust the pH value of the mixed solution to 4 by using acetic acid, stir at 50°C for 2 h until the mixed solution is clear and transparent; then slowly add a catalyst of an aqueous solution of boron trifluoride ether, the mass of boron trifluoride ether is 0.1% of the mass of trimethylethoxysilane, and react at 60°C for 4 h, add an aqueous solution of NaOH until the pH value is neutral, and recover the solvent. After recovering the solvent, an organic silicon modified polysaccharide non-ionic emulsifier OP4 is obtained.

[0032] Mix 30 parts of the polysaccharide emulsifier OP4 prepared in the previous step and 100 parts of the epoxy resin E44, heat in a water bath at 55°C, disperse at a high speed of 3500 r / min, and slowly add water dropwise until the viscosity of the system suddenly decreases from water-in-oil to oil-in-water, add water to a total amount of 130 parts, and continue to disperse at a high speed of 3500 r / min for 0.5 h. A non-ionic waterborne epoxy emulsion WE4 is obtained.

[0033] Example 5

[0034] Add 60 g of propyldimethylchlorosilane (C3H7(CH3)2SiCl) and carboxylated dextran with an average molecular weight of 6000 Da into 120 ml of a mixed solvent of water-methanol (water to methanol in a volume ratio of 1:3) in sequence, wherein the molar ratio of propyldimethylchlorosilane to carboxylated dextran with 6000 Da is 1:1; adjust the pH value of the mixed solution to 5 by using acetic acid, stir at 35°C for 4 h until the mixed solution is clear and transparent; then slowly add a catalyst of an aqueous solution of boron trifluoride ether, the mass of boron trifluoride ether is 1.5% of the mass of propyldimethylchlorosilane, and react at 60°C for 2 h, add an aqueous solution of NaOH until the pH value is neutral, and recover the solvent. After recovering the solvent, an organic silicon modified polysaccharide non-ionic emulsifier OP5 is obtained.

[0035] Mix 25 parts of the polysaccharide emulsifier OP5 prepared in the previous step and 100 parts of epoxy resin E51, heat in a water bath at 50°C, disperse at a high speed of 3000 r / min, and slowly add water dropwise until the viscosity of the system suddenly decreases from water-in-oil to oil-in-water, and then add water to a total amount of 125 parts, and continue to disperse at a high speed of 3000 r / min for 0.5 h to obtain a non-ionic water-based epoxy emulsion WE5.

[0036] Example 6

[0037] Add 60 g of dimethyl dichlorosilane ((CH3)2SiCl2) and carboxylated dextran with an average molecular weight of 7000 Da into 120 ml of a mixed solvent of water-methanol (water to methanol in a volume ratio of 1:3) in sequence, wherein the molar ratio of dimethyl dichlorosilane to 7000 Da carboxylated dextran is 1:2; adjust the pH value of the mixed solution to about 4 by using acetic acid, stir at 40°C for 2 h until the mixed solution is clear and transparent; then slowly add a catalyst of boron trifluoride ether aqueous solution, the mass of boron trifluoride ether is 1.0% of the mass of dimethyl dichlorosilane, and react at 40°C for 6 h, add KOH aqueous solution until the pH value is neutral, and then recover the solvent to obtain the non-ionic polysaccharide emulsifier OP6 modified by silicone.

[0038] Mix 35 parts of the polysaccharide emulsifier OP6 prepared in the previous step and 100 parts of epoxy resin E44, heat in a water bath at 55°C, disperse at a high speed of 4000 r / min, and slowly add water dropwise until the viscosity of the system suddenly decreases from water-in-oil to oil-in-water, and then add water to a total amount of 135 parts, and continue to disperse at a high speed of 4000 r / min for 0.5 h to obtain a non-ionic water-based epoxy emulsion WE6.

[0039] Example 7

[0040] Add 60 g of propyl trichlorosilane (C3H7SiCl3) and carboxylated dextran with an average molecular weight of 9000 Da into 120 ml of a mixed solvent of water-methanol (water to methanol in a volume ratio of 1:3) in sequence, wherein the molar ratio of propyl trichlorosilane to 9000 Da carboxylated dextran is 1:3; adjust the pH value of the mixed solution to about 4 by using acetic acid, stir at 60°C for 0.5 h until the mixed solution is clear and transparent; then slowly add a catalyst of boron trifluoride ether aqueous solution, the mass of boron trifluoride ether is 5% of the mass of propyl trichlorosilane, and react at 55°C for 5 h, add KOH aqueous solution until the pH value is neutral, and then recover the solvent to obtain the non-ionic polysaccharide emulsifier OP7 modified by silicone.

[0041] The nonionic emulsifier OP7 prepared in the above step 30 parts and 50 parts of epoxy resin E44, 50 parts of epoxy resin E51 are mixed, heated in a water bath at 60°C, dispersed at a high speed of 4000 r / min, and water is slowly added dropwise until the viscosity of the system suddenly decreases from water-in-oil to oil-in-water, the total amount of water is added to 130 parts, and the high-speed dispersion is continued at 4000 r / min for 0.5 h, thereby obtaining a nonionic waterborne epoxy emulsion WE7.

[0042] Comparative example:

[0043] The bisphenol A epoxy resin E51 is mixed with polyethylene glycol 4000 at a molar ratio of 1:1, heated to 60°C, and when the reaction mixture is melted, the catalyst boron trifluoride ether solution is slowly added dropwise, the mass of boron trifluoride ether is 0.5% of the mass of bisphenol A epoxy resin E51; the temperature is raised to 65°C and reacted for 4 h, thereby obtaining a nonionic emulsifier OP0.

[0044] The nonionic emulsifier OP0 prepared in the above step 20 parts and 100 parts of epoxy resin E51 are mixed, heated in a water bath at 50°C, dispersed at a high speed of 2500 r / min, and water is slowly added dropwise until the viscosity of the system suddenly decreases from water-in-oil to oil-in-water, the total amount of water is added to 120 parts, and the high-speed dispersion is continued at 2500 r / min for 0.5 h, thereby obtaining a nonionic waterborne epoxy emulsion WE0.

[0045] The performance test results of the waterborne epoxy emulsion WE0-WE7 prepared in the above examples are shown in Table 1; and the waterborne epoxy emulsion WE0-WE7 is mixed with a waterborne epoxy curing agent at a certain mass ratio to form a WE0-WE7 cured film, and the main performance of the cured film is shown in Table 2.

[0046] The waterborne epoxy curing agent is a modified polyamine with a solid content of 50%, a pH of 9-10, a rotary viscosity of 630 mpa﹒s at 25°C, and an active hydrogen equivalent of 230 (solid parts); the amount of waterborne epoxy curing agent is calculated according to the formula: W (%) = active hydrogen equivalent in curing agent x epoxy value.

[0047] Table 1 and Table 2 are respectively the main performance parameters of the nonionic waterborne epoxy emulsion WE0-WE7 and the cured film in the examples.

[0048] Table 1 Main performance parameters of WE0-WE7 in the examples

[0049]

[0050] Table 2 Main performance parameters of WE0-WE7 cured film in the examples

[0051]

[0052] From table 1, it can be seen that the average particle sizes of WE1-WE7 and the comparative sample WE0 are all about 1 μm, the particle sizes are small, and the storage stability is excellent; the epoxy value is mainly related to the proportion of bisphenol A epoxy resin component in the emulsion and the epoxy value of the epoxy resin itself.

[0053] From table 2, it can be seen that the waterborne epoxy emulsion WE1-1E7 emulsified by the polysaccharide emulsifier modified by organosilicon has obviously improved hydrophobicity due to the introduction of organosilicon component, the contact angle of the cured film with water is all more than 90°, the surface has good hydrophobicity, thus the water absorption in the water, acid and alkali media is all greatly reduced compared with the comparative sample, and the water resistance and corrosion resistance of the waterborne epoxy emulsion cured film are improved; at the same time, under the synergistic toughening effect of carboxymethyl dextran and organosilicon, the tensile strength and flexibility of the waterborne epoxy emulsion cured film are significantly improved.

[0054] Although the embodiments of the present application have been shown and described, it is to be understood that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a nonionic epoxy resin emulsifier, characterized in that, The preparation method is as follows: An organosilane containing a hydrolyzable functional group and carboxylated dextran are sequentially added to a water-methanol mixed solvent. The pH of the mixture is adjusted to 3-5 using an organic acid, and the mixture is stirred at 35-60℃ for 0.5-4 hours until it becomes clear and transparent. Then, an aqueous solution of boron trifluoride ether catalyst is slowly added dropwise, and the reaction is carried out at 40-60℃ for 2-6 hours. Alkali solution is added dropwise until the pH is neutral. After recovering the solvent, the organosilicon-modified polysaccharide epoxy resin nonionic emulsifier OP is obtained. The structural formula of the organosilane containing the hydrolyzable functional group is: R n SiX 4-n Where X is a monovalent hydrolyzable functional group, and Si-X can be hydrolyzed to Si-OH; R is an alkyl group, and n is 1~3; X is a halogen or alkoxy group; The molar ratio of the organosilane containing hydrolyzable functional groups to the carboxylated dextran is 1:1 to 3, the volume ratio in the water-methanol mixed solvent is 1:3, the mass of boron trifluoride diethyl ether is 0.1% to 5% of the mass of the organosilane, and the average molecular weight of the carboxylated dextran is 4000 to 9000 Da.

2. The method for preparing the epoxy resin nonionic emulsifier according to claim 1, characterized in that: The organosilane containing a hydrolyzable functional group is one of propyltrimethoxysilane, propyltriethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, propyldimethylchlorosilane, dimethyldichlorosilane, and propyltrichlorosilane.

3. The method for preparing the epoxy resin nonionic emulsifier according to claim 1, characterized in that: The alkaline solution is a sodium hydroxide solution or a potassium hydroxide solution.

4. An epoxy resin nonionic emulsifier OP prepared by the preparation method of the epoxy resin nonionic emulsifier according to any one of claims 1-3.

5. An aqueous epoxy emulsion, characterized in that, Prepared by the following method: Mix the OP of claim 4 with bisphenol A epoxy resin, heat in a water bath at 50°C to 60°C, disperse at high speed, and slowly add water dropwise until the viscosity of the system suddenly decreases from water-in-oil to oil-in-water. Add water to adjust the solid content of the waterborne epoxy emulsion, and continue high-speed dispersion for 0.5 to 1 hour to obtain a nonionic waterborne epoxy emulsion.

6. The aqueous epoxy emulsion according to claim 5, characterized in that: The amount of OP added is 20-35 parts by weight, and the amount of bisphenol A epoxy resin is 100 parts, wherein the bisphenol A epoxy resin is at least one of epoxy E44 and epoxy E51.

7. The aqueous epoxy emulsion according to claim 6, characterized in that: Disperse at a speed of 2000 r / min to 4000 r / min.

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