Preparation method of modified epoxy resin

Abstract

The invention discloses a preparation method of modified epoxy resin, which comprises the following steps: (1) weighing bisphenol S, bisphenol A, epoxy chloropropane and a catalyst, and preparing to obtain a modified bisphenol compound; (2) weighing a modified bisphenol compound, a disulfone compound, epoxy chloropropane and a sodium hydroxide solution; (3) adding a bisphenol compound, a disulfone compound and epichlorohydrin into a reaction container, fully stirring and mixing to obtain an intermediate, and adding a sodium hydroxide solution to start an etherification reaction to form a prepolymer; (4) after the etherification reaction is finished, continuously adding a sodium hydroxide solution to carry out ring-closure reaction, and removing HCl to form modified epoxy resin; and (5) after the reaction is finished, recovering unreacted raw materials through reduced pressure distillation, then washing the modified epoxy resin with water, and then removing impurities and the solvent to obtain the purified modified epoxy resin. According to the invention, bisphenol S is modified by bisphenol A, so that the adhesive property of the epoxy resin is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of epoxy resins, and in particular to a method for preparing a modified epoxy resin. Background Art

[0002] Epoxy resin is usually a liquid resin system, which can achieve its final use purpose after being cured at room temperature or heated. Epoxy resin has a small shrinkage rate during the curing reaction, and its cured product has excellent adhesion, heat resistance, chemical resistance, mechanical properties and electrical properties. It plays an important role in electronics, electrical, mechanical manufacturing, chemical corrosion protection, aerospace, shipping, chemical building materials, water conservancy and electricity and many other industrial fields. It is a variety of thermosetting resins with a large application volume and has become an indispensable basic material in various industrial fields.

[0003] After curing, epoxy resin has a high cross-linking density and a large rigidity of the cross-linking network skeleton, which makes it difficult for the molecular chains to slide relative to each other. As a result, it has the disadvantages of being brittle, poor in fatigue resistance, heat resistance, and impact toughness, which limits its application. Therefore, how to prepare modified epoxy resin with high bonding performance has become a problem that needs to be solved urgently. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a modified epoxy resin. The preparation process is simple and easy to control. By combining bisphenol and bissulfone, the crosslinking density and molecular chain rigidity of the epoxy resin are changed, and the mechanical strength, heat resistance, chemical corrosion resistance and bonding performance of the epoxy resin are significantly enhanced, and the bonding performance is enhanced by 30-80%.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solution: A method for preparing a modified epoxy resin of the present invention has the following innovative features: comprising the following steps: (1) According to a set ratio, bisphenol S, bisphenol A, epichlorohydrin and a catalyst are weighed in order to prepare a modified bisphenol compound; (2) According to the set ratio, weigh the modified bisphenol compound, the bissulfone compound, epichlorohydrin and the sodium hydroxide solution in order; (3) firstly, a bisphenol compound, a bissulfone compound and epichlorohydrin are added into a reaction container in a one-time manner, and then stirred and mixed to obtain an intermediate, and then a sodium hydroxide solution is added to initiate an etherification reaction to form a prepolymer; (4) After the etherification reaction is completed, sodium hydroxide solution is continued to be added to cause a ring-closing reaction to remove HCl, thereby forming a modified epoxy resin; (5) After the reaction is completed, the unreacted raw materials are recovered by vacuum distillation, and then the modified epoxy resin is washed with water to remove impurities and solvents, thereby obtaining a purified modified epoxy resin.

[0006] Preferably, in the above step (1), the specific process for preparing the modified bisphenol compound is: (1.1) Add bisphenol S, bisphenol A and epichlorohydrin into a reaction container and stir and mix them in an oil bath until the solution in the reaction container becomes clear and transparent; (1.2) Then, the catalyst is added to the reaction vessel at a fixed rate and the catalytic reaction is allowed to proceed for a certain period of time; (1.3) After the reaction is completed, filter the reaction solution with a Buchner funnel, remove the precipitate, add toluene to dissolve it, and then wash and separate it with distilled water repeatedly until the aqueous phase is neutral; (1.4) After vacuum distillation and drying, an active diluent is first added, and then a curing agent is added to obtain a modified bisphenol compound.

[0007] Preferably, in the above step (1.1), the molar ratio of bisphenol S, bisphenol A and epichlorohydrin is 3:2:75, and they are added into the reaction container in a one-time feeding manner.

[0008] Preferably, in the above step (1.2), the catalyst is a 25% to 35% sodium hydroxide solution, and the catalytic reaction temperature is 90 to 100° C., and the reaction time is 8 to 9 hours.

[0009] Preferably, in the above step (1.4), drying is performed at 120°C for 3 hours; the added active diluent is ethylene glycol diglycidyl ether epoxy, and its amount is 15% to 20%; the added curing agent is a low molecular weight polyamide resin, and it is first cured at 23°C for 24 hours, then heated to 100°C, and cured at this temperature for 1 hour.

[0010] Preferably, in the above step (2), the molar ratio of the bisphenol compound to the bissulfone compound is 1:1, and the molar ratio of the bisphenol compound to epichlorohydrin is 1:1-10.

[0011] Preferably, in the above step (3), the temperature of the etherification reaction is 60-70° C., and the molar ratio of the intermediate to the sodium hydroxide solution is 1:1-10.

[0012] Preferably, in the above step (4), the temperature of the ring-closing reaction is 70-85° C., the reaction time is 2-4 h, and the molar ratio of the prepolymer to the sodium hydroxide solution is 1:1-10.

[0013] Preferably, the stirring rate in the step is 50 rpm to 400 rpm.

[0014] Beneficial effects of the present invention: (1) The preparation process of the present invention is simple and easy to control. By combining bisphenol and bissulfone, the crosslinking density and molecular chain rigidity of the epoxy resin are changed, and the mechanical strength, heat resistance, chemical corrosion resistance and bonding performance of the epoxy resin are significantly enhanced, and the bonding performance is enhanced by 30-80%; (2) The present invention modifies bisphenol S by using bisphenol A, thereby significantly improving the shear strength and bonding performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 The present invention is a schematic flow chart of a method for preparing a modified epoxy resin. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be clearly and completely described below through specific implementation methods.

[0018] A method for preparing a modified epoxy resin of the present invention, as Figure 1 As shown, the following steps are included: (1) According to a set ratio, bisphenol S, bisphenol A, epichlorohydrin and a catalyst are weighed in order to prepare a modified bisphenol compound.

[0019] In the above steps, the specific process for preparing the modified bisphenol compound is: (1.1) Add bisphenol S, bisphenol A and epichlorohydrin into a reaction container and stir and mix them in an oil bath until the solution in the reaction container becomes clear and transparent; The molar ratio of bisphenol S, bisphenol A and epichlorohydrin is 3:2:75, and they are added into the reaction container in a one-time feeding manner.

[0020] Since the viscosity of bisphenol S epoxy resin is relatively large, the adhesive prepared into it does not wet the surface of the bonded material well and has low bonding strength. To solve this problem, the present invention uses a physical blending method to modify bisphenol S by bisphenol A, that is, adding bisphenol A to destroy the crystallinity of bisphenol S, thereby increasing the shear strength and bonding performance. At this time, the shear strength is 9.35Mpa and the viscosity of the blended resin is 37000mPa·s.

[0021] The invention increases shear strength and bonding performance by physically blending bisphenol S and bisphenol A.

[0022] (1.2) Then, the catalyst is added to the reaction vessel at a fixed rate and the catalytic reaction is allowed to proceed for a certain period of time; The catalyst is 25% to 35% sodium hydroxide solution, and the catalytic reaction temperature is 90 to 100°C, and the reaction time is 8 to 9 hours.

[0023] (1.3) After the reaction is completed, the reaction solution is filtered using a Buchner funnel to remove the precipitate and then toluene is added to dissolve it. The solution is then repeatedly washed and separated using distilled water until the aqueous phase is neutral.

[0024] (1.4) After vacuum distillation and drying, a reactive diluent is first added, and then a curing agent is added to obtain a modified bisphenol compound; Among them, drying is carried out at 120°C for 3 hours; the added active diluent is ethylene glycol diglycidyl ether epoxy, and its dosage is 15%~20%, so as to increase the wetting ability of the adhesive on the bonded surface by adding the active diluent containing epoxy group; the added curing agent is low molecular weight polyamide resin, and 15% low molecular weight polyamide resin is added, and then it is cured at 23°C for 24 hours, and then the temperature is increased to 100°C and cured at this temperature for 1 hour.

[0025] (2) According to the set ratio, weigh the modified bisphenol compound, the bissulfone compound, epichlorohydrin and the sodium hydroxide solution in order; In the above steps, the molar ratio of the bisphenol compound to the bissulfone compound is 1:1, and the molar ratio of the bisphenol compound to epichlorohydrin is 1:1-10.

[0026] (3) firstly, a bisphenol compound, a bissulfone compound and epichlorohydrin are added into a reaction container in a one-time manner, and then stirred and mixed to obtain an intermediate, and then a sodium hydroxide solution is added to initiate an etherification reaction to form a prepolymer; In the above steps, the temperature of the etherification reaction is 60-70° C., and the molar ratio of the intermediate to the sodium hydroxide solution is 1:1-10.

[0027] (4) After the etherification reaction is completed, sodium hydroxide solution is continued to be added to cause a ring-closing reaction to remove HCl, thereby forming a modified epoxy resin; In the above steps, the temperature of the ring-closing reaction is 70-85° C., the reaction time is 2-4 hours, and the molar ratio of the prepolymer to the sodium hydroxide solution is 1:1-10.

[0028] (5) After the reaction is completed, the unreacted raw materials are recovered by vacuum distillation, and then the modified epoxy resin is washed with water to remove impurities and solvents, thereby obtaining a purified modified epoxy resin.

[0029] The stirring rate in the steps of the present invention is 50 rpm to 400 rpm.

[0030] Beneficial effects of the present invention: (1) The preparation process of the present invention is simple and easy to control. By combining bisphenol and bissulfone, the crosslinking density and molecular chain rigidity of the epoxy resin are changed, and the mechanical strength, heat resistance, chemical corrosion resistance and bonding performance of the epoxy resin are significantly enhanced, and the bonding performance is enhanced by 30-80%; (2) The present invention modifies bisphenol S by using bisphenol A, thereby significantly improving the shear strength and bonding performance.

[0031] The embodiments described above are merely descriptions of preferred implementation modes of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary engineering technicians in the field should fall within the protection scope of the present invention. The technical contents for which protection is sought in the present invention have been fully recorded in the technical requirements.

Claims

1. A method for preparing a modified epoxy resin, characterized in that The following steps are involved: (1) According to a set ratio, bisphenol S, bisphenol A, epichlorohydrin and a catalyst are weighed in order to prepare a modified bisphenol compound; (2) According to the set ratio, weigh the modified bisphenol compound, the bissulfone compound, epichlorohydrin and the sodium hydroxide solution in order; (3) firstly, a bisphenol compound, a bissulfone compound and epichlorohydrin are added into a reaction container in a one-time manner, and then stirred and mixed to obtain an intermediate, and then a sodium hydroxide solution is added to initiate an etherification reaction to form a prepolymer; (4) After the etherification reaction is completed, sodium hydroxide solution is continued to be added to cause a ring-closing reaction to remove HCl, thereby forming a modified epoxy resin; (5) After the reaction is completed, the unreacted raw materials are recovered by vacuum distillation, and then the modified epoxy resin is washed with water to remove impurities and solvents, thereby obtaining a purified modified epoxy resin.

2. A method for preparing a modified epoxy resin according to claim 1, characterized in that: In the above step (1), the specific process for preparing the modified bisphenol compound is as follows: (1.1) Add bisphenol S, bisphenol A and epichlorohydrin into a reaction container and stir and mix them in an oil bath until the solution in the reaction container becomes clear and transparent; (1.2) Then, the catalyst is added to the reaction vessel at a fixed rate and the catalytic reaction is allowed to proceed for a certain period of time; (1.3) After the reaction is completed, filter the reaction solution with a Buchner funnel, remove the precipitate, then add toluene to dissolve it, and then wash and separate the solution repeatedly with distilled water until the aqueous phase is neutral; (1.4) After vacuum distillation and drying, an active diluent is first added, and then a curing agent is added to obtain a modified bisphenol compound.

3. A method for preparing a modified epoxy resin according to claim 2, characterized in that: In the above step (1.1), the molar ratio of bisphenol S, bisphenol A and epichlorohydrin is 3:2:75, and they are added into the reaction container in a one-time feeding manner.

4. A method for preparing a modified epoxy resin according to claim 2, characterized in that: In the above step (1.2), the catalyst is selected from 25% to 35% sodium hydroxide solution, and the catalytic reaction temperature is 90 to 100° C., and the reaction time is 8 to 9 hours.

5. A method for preparing a modified epoxy resin according to claim 2, characterized in that: In the above step (1.4), drying is performed at 120°C for 3 hours; the active diluent added is ethylene glycol diglycidyl ether epoxy, and the amount thereof is 15% to 20%; the curing agent added is a low molecular weight polyamide resin, and the curing is first performed at 23°C for 24 hours, then the temperature is raised to 100°C, and the curing is performed at this temperature for 1 hour.

6. A method for preparing a modified epoxy resin according to claim 1, characterized in that: In the above step (2), the molar ratio of the bisphenol compound to the bissulfone compound is 1:1, and the molar ratio of the bisphenol compound to epichlorohydrin is 1:1-10.

7. A method for preparing a modified epoxy resin according to claim 1, characterized in that: In the above step (3), the temperature of the etherification reaction is 60-70° C., and the molar ratio of the intermediate to the sodium hydroxide solution is 1:1-10.

8. A method for preparing a modified epoxy resin according to claim 1, characterized in that: In the above step (4), the temperature of the ring-closing reaction is 70-85°C, the reaction time is 2-4 hours, and the molar ratio of the prepolymer to the sodium hydroxide solution is 1:1-10.

9. The method for preparing a modified epoxy resin according to claim 1, characterized in that: The stirring rate in the step is 50 rpm to 400 rpm.

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