A method for preparing epoxy resin

Abstract

The present invention proposes a method for preparing an epoxy resin, which belongs to the technical field of resin synthesis. The method for preparing the epoxy resin comprises the following steps: 1) under nitrogen protection, epichlorohydrin and phenolic resin are added to a high-speed shearing machine for shearing and stirring to obtain a mixed material; 2) the mixed material is heated to 45-65°C, an alkaline catalyst is added, and the mixture is transferred to a high-pressure homogenizer after reacting for 1-4 hours; 3) the reaction material is homogenized in a high-pressure homogenizer, and an alkaline catalyst is added dropwise during homogenization to obtain a semi-finished product; 4) the semi-finished product is placed in a thin film evaporator to remove epichlorohydrin to obtain an epoxy resin. The method for preparing the epoxy resin provided by the present invention has a short reaction time, high reaction efficiency, can be produced continuously, has few side reactions, and is environmentally friendly.

Description

Technical Field

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

[0002] In the process of preparing epoxy resin, many raw materials are needed, but these raw materials are often mixed by adding them one by one, and the mixing effect cannot be guaranteed. At the same time, the viscosity of the prepared resin is generally controlled by adding a regulator to adjust the viscosity. This method will affect the properties of the preparation itself, and the environmental protection of the treatment cannot be guaranteed, which will produce waste. In addition, epoxy resin is basically prepared intermittently, which not only takes a long time to react, resulting in low production efficiency; but also each step of the operation takes a long time in the reactor, and multiple groups of reactors are needed to increase production capacity, resulting in large equipment investment. Summary of the invention

[0003] The invention provides a method for preparing an epoxy resin. The method has short reaction time, can be continuously produced, has high production efficiency and has few side reactions.

[0004] In order to achieve the above object, the present invention provides a method for preparing an epoxy resin, comprising the following steps:

[0005] 1) Under nitrogen protection, epichlorohydrin and phenolic resin are added into a high-speed shearing machine for shearing and stirring to obtain a mixed material;

[0006] 2) heating the mixture to 45-65° C., adding an alkaline catalyst, reacting for 1-4 hours, and then transferring the mixture to a high-pressure homogenizer;

[0007] 3) homogenizing the reaction materials in a high-pressure homogenizer, and adding a basic catalyst dropwise during homogenization to obtain a semi-finished product;

[0008] 4) The semi-finished product is placed in a thin film evaporator to remove epichlorohydrin to obtain epoxy resin.

[0009] Preferably, the phenolic resin in step 1) is o-cresol phenolic resin, phenol phenolic resin, bisphenol A phenolic resin, bisphenol F or bisphenol A.

[0010] Preferably, the molar ratio of epichlorohydrin to phenolic resin in step 1) is 1 to 8:1.

[0011] Preferably, the alkaline catalyst in step 2) is sodium hydroxide or potassium hydroxide; the molar ratio of the alkaline catalyst to the phenolic resin is 0.05 to 0.3:1.

[0012] Preferably, the alkaline catalyst in step 3) is sodium hydroxide or potassium hydroxide; the molar ratio of the alkaline catalyst to the phenolic resin is 0.45 to 1.95:1.

[0013] Preferably, in step 3), a reducing decolorizing agent is added dropwise while homogenizing; the reducing decolorizing agent is zinc powder or sodium borohydride; and the molar ratio of the reducing decolorizing agent to the phenolic resin is 0.001 to 0.01:1.

[0014] Preferably, the pressure during high pressure homogenization in step 3) is 3-100 MPa, the temperature is 30-80° C., and the time is 10-120 min.

[0015] Preferably, in step 4), the temperature in the thin film evaporator is controlled at 100-200°C.

[0016] Preferably, after removing epichlorohydrin in step 4), washing and desolventizing are performed in sequence; toluene, xylene, cyclohexanone, acetone or methyl isobutyl ketone is used for dissolution during washing, the washing temperature is 50 to 90° C., and the washing times are 3 to 7 times.

[0017] Preferably, a thin film evaporator is used for desolventizing, and the temperature in the thin film evaporator is controlled at 100-200°C.

[0018] Compared with the prior art, the advantages and positive effects of the present invention are:

[0019] The preparation method of the epoxy resin provided by the present invention places the prepared mixture in a high-speed shearing machine and a high-pressure homogenizer during the preparation process. Compared with the traditional method of adjusting the viscosity of the mixture by adding reagents, this method can be achieved by a purely physical method without adding additional additives, thereby not changing the composition of the mixture and reducing the occurrence of side reactions; and under the action of the high-pressure homogenizer, the reaction time can be shortened, the probability of side reactions is further reduced, the reaction efficiency is improved, and continuous production is possible; at the same time, the treatment is environmentally friendly.

[0020] At the same time, the method can collect the heat generated by the reactions in each step and the excess heat in the reaction process, collect and utilize the heat generated in the chemical reaction process itself and the excess heat, avoid heat waste, significantly improve the dehydration efficiency of semi-finished products, reduce the energy consumption of the preparation process, and is suitable for industrial promotion. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0022] The present invention provides a method for preparing an epoxy resin, comprising the following steps:

[0023] 1) Under nitrogen protection, epichlorohydrin and phenolic resin are added into a high-speed shearing machine for shearing and stirring to obtain a mixed material;

[0024] 2) heating the mixture to 45-65° C., adding an alkaline catalyst, reacting for 1-4 hours, and then transferring the mixture to a high-pressure homogenizer;

[0025] 3) homogenizing the reaction materials in a high-pressure homogenizer, and adding a basic catalyst dropwise during homogenization to obtain a semi-finished product;

[0026] 4) The semi-finished product is placed in a thin film evaporator to remove epichlorohydrin to obtain epoxy resin.

[0027] The present invention adds epichlorohydrin and phenolic resin in a high-speed shearing machine under nitrogen protection to perform shearing and stirring to obtain a mixed material. In the present invention, the phenolic resin is preferably o-cresol phenolic resin, phenol phenolic resin, bisphenol A phenolic resin, bisphenol F or bisphenol A. In the present invention, the molar ratio of epichlorohydrin to phenolic resin is preferably 1 to 8:1.

[0028] After obtaining the mixed material, the present invention heats the mixed material to 45-65° C., adds an alkaline catalyst, reacts for 1-4 hours, and then transfers the liquid to a high-pressure homogenizer. In the present invention, the alkaline catalyst is preferably sodium hydroxide or potassium hydroxide; the molar ratio of the alkaline catalyst to the phenolic resin is preferably 0.05-0.3:1. In the present invention, nitrogen is continuously introduced during the reaction for protection.

[0029] After the liquid is transferred to the high-pressure homogenizer, the present invention homogenizes the reaction material in the high-pressure homogenizer, and drops an alkaline catalyst during homogenization to obtain a semi-finished product. In the present invention, the pressure during high-pressure homogenization is preferably 3-100Mpa, the temperature is preferably 30-80°C, and the time is preferably 10-120min. In the present invention, the alkaline catalyst is preferably sodium hydroxide or potassium hydroxide; the molar ratio of the alkaline catalyst to the phenolic resin is preferably 0.45-1.95:1. In the present invention, a reducing decolorant is preferably added dropwise while homogenizing; the reducing decolorant is preferably zinc powder or sodium borohydride; the mass ratio of the reducing decolorant to the phenolic resin is preferably 0.001-0.01:1. The present invention puts the reacting material into a high-pressure homogenizer for high-pressure homogenization. During the high-pressure homogenization process, the material can not only be fully mixed, but also the high-pressure solution quickly passes through the homogenization chamber. Under the action of the booster mechanism, the material will be simultaneously subjected to mechanical forces such as high-speed shearing, high-frequency oscillation, cavitation and convection impact and corresponding thermal effects. The mechanical force and chemical effect caused thereby can induce changes in the physical and structural properties of the material macromolecules, and ultimately achieve the effect of homogenization and viscosity adjustment. The method can achieve viscosity adjustment by purely physical methods, will not change the composition of the mixed material, and will not affect the product properties. Moreover, under the action of the high-pressure homogenizer, the reaction time is shortened, the reaction efficiency is improved, and continuous production is possible; at the same time, the treatment is environmentally friendly.

[0030] After obtaining the semi-finished product, the present invention places the semi-finished product in a thin film evaporator to remove epichlorohydrin to obtain epoxy resin. In the present invention, the temperature in the thin film evaporator is preferably controlled at 100-200°C. In the present invention, washing and desolventizing treatment are performed in sequence after removing epichlorohydrin. In the present invention, toluene, xylene, cyclohexanone, acetone or methyl isobutyl ketone are preferably used for dissolving during the washing, and pure water is added to wash it after the dissolution is complete. In the present invention, the washing temperature is preferably 50-90°C, and the number of washings is preferably 3-7 times. In the present invention, a thin film evaporator is preferably used for desolventizing treatment, and the temperature in the thin film evaporator is preferably controlled at 100-200°C.

[0031] In the present invention, it is preferred to centrally introduce the heat generated during the chemical reaction and the excess heat into the heat pipe to recover the heat, and introduce the heat stored in the heat pipe into the thin film evaporator to provide a heat source to avoid heat waste.

[0032] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0033] Example 1

[0034] S1, selecting raw materials for preparation, including o-cresol phenolic resin, epichlorohydrin and sodium hydroxide, the molar ratio of epichlorohydrin to o-cresol phenolic resin is 4.5:1, and the molar ratio of the total amount of alkaline catalyst to o-cresol phenolic resin is 0.95:1;

[0035] S2, add epichlorohydrin into the high-speed shearing machine, add o-cresol phenolic resin into the high-speed shearing machine, and keep the temperature at 55°C and introduce nitrogen protective gas;

[0036] S3, raising the temperature in the high-speed shearing machine to 60°C, adding alkaline catalyst sodium hydroxide, the molar ratio of the alkaline catalyst to the o-cresol phenolic resin being 0.10:1, mixing and reacting for 3 hours, transferring the liquid, and continuously keeping the temperature and introducing nitrogen protective gas;

[0037] S4, taking out the mixture after the reaction in S3 and transferring it into a high-pressure homogenizer, while dropping the alkaline catalyst and the reducing decolorizing agent zinc powder, reacting in the high-pressure homogenizer for 60 minutes, the molar ratio of the alkaline catalyst to the raw material is 0.85:1, the mass ratio of the reducing decolorizing agent to the phenolic resin is 0.005:1, the homogenizer pressure is 20MPa, and the homogenizer temperature is maintained at 50°C;

[0038] S5, placing the solution after the reaction in S4 in a thin film evaporator to remove epichlorohydrin in the system at 150°C;

[0039] S6, the semi-finished product after removing epichlorohydrin is placed in a washing device, toluene is added to stir and dissolve, and after the dissolution is complete, pure water is added to wash it 3 times to wash away the sodium chloride therein;

[0040] S7, centrally introducing the heat generated in the above reaction into a heat pipe to recover the heat;

[0041] S8. Place the washed resin solution in a thin film evaporator, introduce the heat stored in the heat pipe into the thin film evaporator, and provide a heat source to perform a final rapid desolventizing treatment on the semi-finished product at 150° C. Take out the desolventized finished product, cool it, and store it.

[0042] Example 2

[0043] S1. Selecting raw materials for preparation, including bisphenol A, epichlorohydrin and sodium hydroxide, the molar ratio of epichlorohydrin to bisphenol A is 6.0:1, and the molar ratio of the total amount of alkaline catalyst to bisphenol A is 1.30:1;

[0044] S2, add epichlorohydrin into the high-speed shearing machine, add bisphenol A into the high-speed shearing machine, keep the temperature at 45°C and introduce nitrogen protective gas;

[0045] S3, raising the temperature in the high-speed shearing machine to 55° C., adding alkaline catalyst sodium hydroxide, the molar ratio of the alkaline catalyst to bisphenol A being 0.3:1, mixing and reacting for 2 hours, and then transferring the liquid, and continuously keeping the temperature and introducing nitrogen protective gas;

[0046] S4, taking out the mixture after the reaction in S3 and transferring it into a high-pressure homogenizer, while dropping an alkaline catalyst and a reducing decolorizing agent sodium borohydride, reacting in the high-pressure homogenizer for 90 minutes, the molar ratio of the alkaline catalyst to bisphenol A is 1.0:1, the mass ratio of the reducing decolorizing agent to bisphenol A is 0.008:1, the pressure of the homogenizer is 30 MPa, and the temperature of the homogenizer is maintained at 40°C;

[0047] S5, placing the solution after the reaction in S4 in a thin film evaporator to remove epichlorohydrin in the system at 150°C;

[0048] S6, the semi-finished product after removing epichlorohydrin is placed in a washing device, toluene is added to stir and dissolve, and after the dissolution is complete, pure water is added to wash it 4 times to wash away the sodium chloride therein;

[0049] S7, centrally introducing the heat generated in the above reaction into a heat pipe to recover the heat;

[0050] S8. Place the washed resin solution in a thin film evaporator, introduce the heat stored in the heat pipe into the desolventizing device, and provide a heat source to perform a final rapid desolventizing treatment on the semi-finished product at 150° C. Take out the desolventized finished product, cool it, and store it.

[0051] Example 3

[0052] S1, selecting raw materials for preparation, including phenol novolac resin, epichlorohydrin and sodium hydroxide, the molar ratio of epichlorohydrin to phenol novolac resin is 4.0:1, and the molar ratio of alkaline catalyst to phenol novolac resin is 1.1:1;

[0053] S2, add epichlorohydrin into the high-speed shearing machine, add phenolic resin into the high-speed shearing machine, and continue to keep warm and introduce nitrogen protective gas;

[0054] S3, raising the temperature in the high-speed shearing machine to 55°C, adding alkaline catalyst sodium hydroxide, the molar ratio of the alkaline catalyst to the phenol-formaldehyde resin is 0.08:1, mixing and reacting for 3 hours, and then transferring the liquid, and continuously keeping the temperature and passing nitrogen protective gas;

[0055] S4, taking out the mixture after the reaction in S3 and transferring it into a high-pressure homogenizer, while dropping the alkaline catalyst and the reducing decolorizing agent sodium borohydride, reacting in the high-pressure homogenizer for 30 minutes, the mass ratio of the reducing decolorizing agent to the phenol novolac resin is 0.001:1, the molar ratio of the alkaline catalyst to the phenol novolac resin is 1.02:1, the homogenizer pressure is 10MPa, and the homogenizer temperature is maintained at 50°C;

[0056] S5, placing the solution after the reaction in S4 in a thin film evaporator to remove epichlorohydrin in the system at 150°C;

[0057] S6, placing the semi-finished product after removing epichlorohydrin in a washing device, adding methyl isobutyl ketone to stir and dissolve, and after complete dissolution, adding pure water to wash it 4 times to wash away the sodium chloride in it;

[0058] S7, centrally introducing the heat generated in the above reaction into a heat pipe to recover the heat;

[0059] S8. Place the washed resin solution in a thin film evaporator, introduce the heat stored in the heat pipe into the desolventizing device, and provide a heat source to perform a final rapid desolventizing treatment on the semi-finished product at 200° C. Take out the desolventized finished product, cool it, and store it.

[0060] Example 4

[0061] S1. Selecting raw materials for preparation, including bisphenol F, epichlorohydrin and sodium hydroxide, the molar ratio of epichlorohydrin to bisphenol F is 8:1, and the molar ratio of the alkaline catalyst to bisphenol F is 1.2:1;

[0062] S2, add epichlorohydrin into the high-speed shearing machine, add bisphenol F into the high-speed shearing machine, and continue to keep warm and introduce nitrogen protective gas;

[0063] S3, raising the temperature in the high-speed shearing machine to 50°C, adding alkaline catalyst sodium hydroxide, the molar ratio of the alkaline catalyst to bisphenol F is 0.18:1, mixing and reacting for 3 hours, and then transferring the liquid, and continuously keeping the temperature to pass nitrogen protective gas;

[0064] S4, taking out the mixture after the reaction in S3 and transferring it into a high-pressure homogenizer, while dropping the alkaline catalyst and the reducing decolorizing agent zinc powder, reacting in the high-pressure homogenizer for 90 minutes, the molar ratio of the reducing decolorizing agent to bisphenol F is 0.002:1, the molar ratio of the alkaline catalyst to the raw material is 1.02:1, the homogenizer pressure is 3MPa, and the homogenizer temperature is maintained at 50°C;

[0065] S5, placing the solution after the reaction in S4 in a thin film evaporator to remove epichlorohydrin in the system at 200°C;

[0066] S6, the semi-finished product after removing epichlorohydrin is placed in a washing device, xylene is added to stir and dissolve, and after the dissolution is complete, pure water is added to wash it 4 times to wash away the sodium chloride in it;

[0067] S7, centrally introducing the heat generated in the above reaction into a heat pipe to recover the heat;

[0068] S8. Place the washed resin solution in a thin film evaporator, introduce the heat stored in the heat pipe into the desolventizing device, provide a heat source, remove the solvent in the system at 200°C, and cool and store it.

[0069] Comparative Example 1

[0070] S1, adding o-cresol-formaldehyde resin and epichlorohydrin into a reactor connected to a reflux cooler, wherein the molar ratio of epichlorohydrin to o-cresol-formaldehyde resin is 4.0:1, and completely dissolving at a temperature of 50° C. to obtain a raw material mixed solution;

[0071] S2, adding 50 wt.% NaOH aqueous solution to the raw material reaction liquid obtained in step S1, with the molar ratio of the alkaline catalyst to the o-cresol resin being 0.1:1, and reacting at a temperature of 60° C. for 4 hours to obtain reaction liquid I;

[0072] S3, adding 50% wt. NaOH aqueous solution to the reaction solution I obtained in step S2 at a temperature of 63° C. and a vacuum degree of 10 KPa for 4 hours, with the molar ratio of the alkaline catalyst to the o-cresol resin being 0.85:1, and performing a reflux dehydration reaction to obtain a reaction solution II;

[0073] 4) recovering excess epichlorohydrin in the reaction solution II obtained in step S3 at a temperature of 130° C. and a vacuum degree of 3 KPa to obtain a crude phenolic epoxy resin product;

[0074] 5) adding 160 g of methyl isobutyl ketone to dissolve the crude phenolic epoxy resin obtained in step 4), adding 50 wt.% of NaOH aqueous solution, and performing a refining reaction at 80° C. for 2 hours to obtain a reaction solution III;

[0075] 6) Add 100 g of pure water to the reaction solution III obtained in step 5), add 2 wt.% of phosphoric acid for neutralization, neutralize the reaction solution, separate the liquids, and recover methyl isobutyl ketone at a temperature of 160° C. and a pressure of 3 KPa to obtain o-cresol epoxy resin.

[0076] Performance Testing

[0077] The yield, epoxy equivalent and hydrolyzed chlorine of the epoxy resins prepared in the examples and comparative examples were tested, and the specific results are shown in Table 1.

[0078] Table 1 Performance test results

[0079] Epoxy equivalent Hydrolyzed chlorine / ppm Reaction time / h Yield / % Example 1 201 68 4 97 Example 2 186 70 3.5 97 Example 3 180 58 3.5 97 Example 4 173 64 4.5h 97 Comparative Example 1 186 132 8h 97

[0080] It can be seen from Table 1 that the method provided by the present invention is time-consuming, has a higher reaction efficiency, and has lower hydrolyzed chlorine and relatively fewer by-products.

[0081] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing an epoxy resin, characterized in that: The steps include: 1) Under nitrogen protection, epichlorohydrin and phenolic resin are added into a high-speed shearing machine for shearing and stirring to obtain a mixed material; 2) heating the mixture to 45-65° C., adding an alkaline catalyst, reacting for 1-4 hours, and then transferring the mixture to a high-pressure homogenizer; 3) homogenizing the reaction materials in a high-pressure homogenizer, and adding a basic catalyst dropwise during homogenization to obtain a semi-finished product; 4) The semi-finished product is placed in a thin film evaporator to remove epichlorohydrin to obtain epoxy resin.

2. The preparation method according to claim 1, characterized in that: The phenolic resin in step 1) is o-cresol phenolic resin, phenol phenolic resin, bisphenol A phenolic resin or bisphenol F phenolic resin.

3. The preparation method according to claim 1, characterized in that: The molar ratio of epichlorohydrin to phenolic resin in step 1) is 1 to 8:

1.

4. The preparation method according to claim 1, characterized in that: In step 2), the alkaline catalyst is sodium hydroxide or potassium hydroxide; the molar ratio of the alkaline catalyst to the phenolic resin is 0.05 to 0.3:

1.

5. The preparation method according to claim 1, characterized in that: In step 3), the alkaline catalyst is sodium hydroxide or potassium hydroxide; the molar ratio of the alkaline catalyst to the phenolic resin is 0.45 to 1.95:

1.

6. The preparation method according to claim 1, characterized in that: In step 3), a reducing decolorizing agent is added dropwise while homogenizing; the reducing decolorizing agent is zinc powder or sodium borohydride; and the molar ratio of the reducing decolorizing agent to the phenolic resin is 0.001 to 0.01:

1.

7. The preparation method according to claim 1, characterized in that: The pressure during high pressure homogenization in step 3) is 3-100 MPa, the temperature is 30-80° C., and the time is 10-120 min.

8. The preparation method according to claim 1, characterized in that: In step 4), the temperature in the thin film evaporator is controlled at 100-200°C.

9. The preparation method according to claim 1, characterized in that: After removing epichlorohydrin in step 4), washing and desolventizing are performed in sequence; toluene, xylene, cyclohexanone, acetone or methyl isobutyl ketone is used for dissolution during washing, the washing temperature is 50 to 90° C., and the washing times are 3 to 7 times.

10. The preparation method according to claim 9, characterized in that: A thin film evaporator is used for desolventizing, and the temperature in the thin film evaporator is controlled at 100-200°C.