Preparation method of weak-base water-soluble epoxy resin with high photosensitivity

Abstract

The invention relates to a preparation method of weak-base water-soluble epoxy resin with high photosensitivity. The preparation method comprises the following steps: preparation of epoxy chloropropane, preparation of a carbon fiber / epoxy resin composite material, preparation of guaiacol bisphenol (BGF), preparation of guaiacol epoxy resin, preparation of o-cresol formaldehyde epoxy resin, synthesis of o-cresol formaldehyde epoxy acrylate and preparation of weak-base water-soluble photosensitive resin. A chloropropene method, a column chromatography method, a chemical two-step method, a one-step method, a drying process and the like are creatively combined, the prepared weak-base water-soluble epoxy resin has the characteristics of higher photosensitivity, better photosensitivity and acid and alkali resistance, and the weak-base water-soluble epoxy resin has the advantages of convenience in raw material source, low cost, greenness, environment friendliness, higher stability and the like.

Description

Technical Field

[0001] The invention relates to a method for preparing a highly photosensitive weak-base water-soluble epoxy resin, belonging to the technical field of new materials. Background Art

[0002] As an important thermosetting resin, epoxy resin has been widely used in many fields such as coatings, adhesives, and electronic packaging. Traditional epoxy resins usually need to be formed through a certain curing process under the action of acid or amine curing agents. Moreover, ordinary epoxy resins also have obvious defects in water solubility. Most conventional epoxy resins have extremely poor solubility in water due to the characteristics of their chemical structure, which limits their application in some specific fields, such as water-based coatings and water-based adhesives. Although there are some so-called water-soluble epoxy resins on the market, they have problems such as unstable water solubility and poor solubility in weak alkaline environments. Summary of the invention

[0003] In view of the above problems, the present invention provides a method for preparing a highly photosensitizing weakly alkaline water-soluble epoxy resin.

[0004] The invention relates to a method for preparing a weak-base water-soluble epoxy resin with high photosensitivity, comprising the following steps: preparing epichlorohydrin, preparing a carbon fiber / epoxy resin composite material, preparing guaiacol-based bisphenol (BGF), preparing guaiacol-based epoxy resin, preparing o-cresol-formaldehyde epoxy resin, synthesizing o-cresol-formaldehyde epoxy acrylate, and preparing a weak-base water-soluble photosensitive resin.

[0005] Preferably, step (1) preparation of epichlorohydrin Propylene and chlorine are dried, mixed in a certain amount ratio, and introduced into a high-temperature chlorination reactor, and the generated hydrogen chloride is absorbed by lime water solution, and the oil phase is distilled under reduced pressure to obtain allyl chloride, and the prepared allyl chloride mixture is mixed with water under high-speed stirring, and chlorine is introduced to react fully, and then the product is degassed and added to the lime solution, stirred for reaction, separated from the oil phase, and distilled under reduced pressure to obtain epichlorohydrin; Step (2) Preparation of carbon fiber / epoxy resin composite material The epichlorohydrin prepared in step (1) is placed in a beaker together with the epoxy resin and the low molecular weight polyamide curing agent, multi-walled carbon nanotubes are weighed, ultrasonically dispersed in an acetone solution, and then added to the epoxy resin, and vigorously stirred, and the low molecular weight polyamide is added to the epoxy resin mixed with the multi-walled carbon nanotubes, and after mixing evenly, the mixture is poured into the dipping tank of the winding machine for standby use, the prepreg is cut and removed from the winding machine, and allowed to stand at room temperature to allow the residual acetone in the prepreg to fully volatilize, and the prepreg is pressed in an autoclave to obtain a carbon fiber / epoxy resin composite material; Step (3) Preparation of guaiacol-based bisphenol (BGF) First, the carbon fiber / epoxy resin composite material prepared in the above step (2) is prepared for use. At a certain temperature, epichlorohydrin, 4-methylguaiacol and phosphoric acid are respectively added into a three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser. Next, a formaldehyde aqueous solution is slowly added dropwise using a constant pressure dropping funnel. After the addition is completed, a golden yellow product is obtained by heating and constant temperature reaction. Finally, the product is washed with deionized water for several times until it is neutral, and purified by column chromatography to obtain guaiacol-based bisphenol (BGF); Step (4) Preparation of guaiacol-based epoxy resin In a three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser, the guaiacol-based bisphenol (BGF), triethylbenzylammonium chloride (TBAB) and epichlorohydrin prepared in step (3) are added respectively, and reacted at a certain temperature, and the excess epichlorohydrin is removed by vacuum distillation, and toluene and an aqueous NaOH solution are added to the reaction system, and the reaction is continued to obtain a white product, and the crude product is purified by column chromatography to obtain a guaiacol-based epoxy resin; Step (5) Preparation of o-cresol-formaldehyde epoxy resin A certain amount of the epoxy resin cured product of step (4) is taken together with phenolic formaldehyde and oxalic acid, and heated under nitrogen protection. After the heat preservation is completed, a small amount of toluene solvent is added for reaction. Then, sodium hydroxide is added, and the mixture is kept warm with water. Epichlorohydrin is removed in a vacuum. Hot distilled water is added and stirred to fully mix. The aqueous layer is separated and removed. Hot distilled water is added again, and the separated aqueous layer is repeatedly washed with water until the pH value of the separated aqueous layer is neutral. Toluene and other solvents are removed in a vacuum to obtain o-cresol formaldehyde epoxy resin. Step (6) Synthesis of o-cresol-formaldehyde epoxy acrylate Adding a polymerization inhibitor (hydroquinone) and a catalyst (carboxylate) to the o-cresol epoxy resin and the solvent prepared in step (5) at the same time, stirring evenly, slowly adding acrylic acid dropwise using a separatory funnel after the reaction temperature rises, and after the addition is completed, raising the temperature and keeping the temperature until the difference between the measured acid value and the initial acid value is small, thereby obtaining o-cresol epoxy acrylate; Step (7) Preparation of weakly alkaline water-soluble photosensitive resin Take appropriate amounts of o-cresol epoxy acrylate and butyl cellosolve from step (6), add a polymerization inhibitor (hydroquinone) and tetramethylammonium chloride, stir to make a transparent homogeneous solution, then add a toluene solution of maleic anhydride, slowly raise the temperature to the set reaction temperature, react for a period of time, and use reduced pressure distillation to remove the organic solvent to obtain a weakly alkaline water-soluble photosensitive resin.

[0006] The first technical purpose of the present invention is achieved through the following technical solutions: Preferably, step (1) preparation of epichlorohydrin After drying, propylene and chlorine are mixed in a ratio of 4-10:1-5 and introduced into a 1-5L high-temperature oxidation reactor, the reaction time is controlled to be 1-3 minutes, the generated hydrogen chloride is absorbed by a 15-20°C lime aqueous solution, and the oil phase is distilled under reduced pressure to obtain allyl chloride, and the prepared allyl chloride mixture is mixed with water under high-speed stirring, chlorine is introduced and fully reacted, and then the product is degassed and added to the lime solution, stirred for reaction, separated from the oil phase, and distilled under reduced pressure to obtain epichlorohydrin.

[0007] The present invention has the advantage that epichlorohydrin is prepared by using the allyl chloride method in the preparation step, wherein the allyl chloride is directly converted into epichlorohydrin, thereby eliminating the complicated process of reacting allyl chloride with hypochlorous acid to generate dichloropropanol and then further saponifying to generate epichlorohydrin in the traditional method. This direct conversion reduces the generation of intermediate steps and by-products, improves the selectivity and safety of the reaction, makes the preparation of epichlorohydrin more efficient and convenient, and makes the entire preparation step more environmentally friendly and safe, with a broader prospect for use.

[0008] Step (2) Preparation of carbon fiber / epoxy resin composite material The epichlorohydrin prepared in step (1) is placed in a beaker together with 125-150 g of epoxy resin and 75-80 g of a low molecular weight polyamide curing agent. 0.5-0.6% (mass fraction) of multi-walled carbon nanotubes are accurately weighed and ultrasonically dispersed in an acetone solution for 2-3 hours, and then added to the epoxy resin. The mixture is vigorously stirred at 60-65° C. for 1-2 hours. The low molecular weight polyamide is added to the epoxy resin mixed with the multi-walled carbon nanotubes, and after mixing evenly, the mixture is poured into a resin dipping tank of a wire winding machine for standby use. The prepreg is cut and removed from the wire winding machine, and allowed to stand at room temperature for 8-10 hours to allow the residual acetone in the prepreg to fully volatilize. The prepreg is pressed in an autoclave to obtain a carbon fiber / epoxy resin composite material.

[0009] The advantage of adopting the present invention is that high-performance carbon fiber is combined with epoxy resin in the preparation step. Carbon fiber is known for its high tensile strength and elastic modulus. When compounded with epoxy resin, the excellent properties of these two materials are superimposed. Epoxy resin, as a matrix material, can effectively transfer the reinforcing effect of carbon fiber to the entire composite material. The high strength of carbon fiber ensures that the composite material is not easy to break when subjected to load, and the high modulus makes the composite material less deformed when subjected to external force, maintaining good rigidity and stability. These advantages provide good performance and greater stability in the subsequent preparation of new composite resins.

[0010] Preferably, step (3) preparation of guaiacol-based bisphenol (BGF) First, the carbon fiber / epoxy resin composite material prepared in the above step (2) is prepared for use. At 50-60° C., epichlorohydrin, 30-35 g 4-methylguaiacol and 80-90% phosphoric acid are added into a 95-100 mL three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser. Next, a 35-40% formaldehyde aqueous solution is slowly added dropwise using a constant pressure dropping funnel. After the addition is completed, the mixture is heated to 90-92° C. and reacted at a constant temperature for 5-8 hours to obtain a golden yellow product. Finally, the mixture is washed with deionized water for 2-3 times until it is neutral, and purified by column chromatography to obtain guaiacol-based bisphenol BGF.

[0011] Preferably, step (4) preparation of guaiacol-based epoxy resin In a three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser, 13-15 g of the guaiacol-based bisphenol (BGF) prepared in step (3), 0.1-0.3 g of triethylbenzylammonium chloride (TBAB) and 80-100 mL of epichlorohydrin are added respectively, and the mixture is reacted at 90-100° C. for 6-7 hours. Subsequently, the excess epichlorohydrin is removed by reduced pressure distillation, 100-120 mL of toluene and 4.80-5.00 g of a NaOH aqueous solution are added to the reaction system, and the mixture is reacted at 90-100° C. for 3-4 hours to obtain a white product. The crude product is purified by column chromatography to obtain a guaiacol-based epoxy resin.

[0012] The invention has the advantages that, in this step, guaiacol-based bisphenol (BGF) is used to fuse with epoxy resin. Compared with traditional petroleum-based epoxy resin, the preparation process of guaiacol-based epoxy resin is more environmentally friendly, reduces pollution to the environment, and reduces the emission of toxic and harmful substances. In addition, since the benzene ring structure in the guaiacol molecule has strong thermal stability and acid and alkali resistance, the epoxy resin is not easy to decompose or degrade at high temperature and in chemical reactions. The combination of the two improves the overall performance of the guaiacol-based epoxy resin, so that the epoxy resin provides excellent heat resistance and chemical resistance for the subsequent preparation process.

[0013] Preferably, step (5) preparation of o-cresol-formaldehyde epoxy resin Take the epoxy resin cured product of step (4) and mix it with 1-2:0-2 phenolic acid and 0.5-2% oxalic acid, heat it to 75-100°C, then protect it with nitrogen, keep it warm for 4-6 hours, then add 10-15% toluene solvent to react, then add 40-45% sodium hydroxide dropwise for 2-4 hours, keep it warm with water for 1-2 hours, vacuum remove epichlorohydrin, add 45-50mL hot distilled water and stir to mix thoroughly, separate the liquid to remove the water layer, add hot distilled water, wash it repeatedly with water for 4-5 times until the pH value of the separated water layer is neutral, vacuum remove toluene and other solvents to obtain o-cresol epoxy resin.

[0014] The present invention has the advantage that an alkali neutralization reaction is used in the preparation step, and the alkali neutralization reaction helps to reduce by-products such as hydrogen chloride generated during the reaction. The reduction of these by-products not only improves the purity of the product, but also simplifies the subsequent treatment process. In addition, during the preparation process, sodium hydroxide is used as a catalyst to effectively promote the epoxidation reaction between o-cresol-formaldehyde resin and epichlorohydrin. The catalytic effect accelerates the reaction rate, thereby improving the production efficiency.

[0015] Preferably, step (6) the synthesis of o-cresol aldehyde epoxy acrylate Add a polymerization inhibitor (hydroquinone) and a catalyst (carboxylate) to the o-cresol epoxy resin prepared in step (5) and an organic solvent accounting for 65-70% of the resin, stir evenly, heat the reaction to 70-75°C, slowly add acrylic acid dropwise using a separatory funnel, and control the addition to be completed within 1.5-2 hours. Heat the temperature to 85-90°C and keep warm to obtain o-cresol epoxy acrylate.

[0016] Preferably, in step (7), the preparation of a weakly alkaline water-soluble photosensitive resin The o-cresol epoxy acrylate and butyl cellosolve prepared in step (6) are placed in a 250-300 mL beaker, and an inhibitor (hydroquinone) and tetramethylammonium chloride are added at the same time. The temperature is raised to 80-120° C. and stirred for 4-6 hours to make it a transparent homogeneous solution. Then, a toluene solution of maleic anhydride is added. After reacting for 2.5-6 hours, the organic solvent is removed by vacuum distillation to obtain a weakly alkaline water-soluble photosensitive resin.

[0017] The advantage of adopting the present invention is that the weakly alkaline water-soluble photosensitive resin has good solubility under alkaline conditions, which makes it easier to remove the unexposed part during the process of development, cleaning, etc., so as to obtain a clear image. This shows that the preparation improves the photosensitivity of the photosensitive resin in an alkaline environment. Combined with the advantages of the previous raw materials, this type of resin can be quickly cured under ultraviolet light to form a stable polymer structure. The fast light curing speed not only improves the production efficiency, but also helps to reduce energy consumption and pollution in the production process, which complies with the green environmental protection concept.

[0018] In summary, the present invention has the following beneficial effects: 1. The present invention has the advantage that epichlorohydrin is prepared by the allyl chloride method in the preparation step, wherein allyl chloride is directly converted into epichlorohydrin, eliminating the complicated process of reacting allyl chloride with hypochlorous acid to generate dichloropropanol and then further saponifying to generate epichlorohydrin in the traditional method. This direct conversion reduces the generation of intermediate steps and by-products, improves the selectivity and safety of the reaction, makes the preparation of epichlorohydrin more efficient and convenient, and makes the entire preparation step more environmentally friendly and safe, with a broader prospect for use; 2. The present invention has the advantage that high-performance carbon fiber is combined with epoxy resin in the preparation step. Carbon fiber is known for its high tensile strength and elastic modulus. When compounded with epoxy resin, the excellent properties of the two materials are superimposed. Epoxy resin, as a matrix material, can effectively transfer the reinforcing effect of carbon fiber to the entire composite material. The high strength of carbon fiber ensures that the composite material is not easy to break when subjected to load, while the high modulus makes the composite material less deformed when subjected to external force, maintaining good rigidity and stability. These advantages provide good performance and greater stability in the subsequent preparation of new composite resins. 3. The present invention has the advantages that, in this step, guaiacol-based bisphenol (BGF) is used to fuse with epoxy resin. Compared with traditional petroleum-based epoxy resin, the preparation process of guaiacol-based epoxy resin is more environmentally friendly, reduces pollution to the environment, and reduces the emission of toxic and harmful substances. In addition, since the benzene ring structure in the guaiacol molecule has strong thermal stability and acid and alkali resistance, the epoxy resin is not easy to decompose or degrade at high temperature and in chemical reactions. The combination of the two improves the overall performance of the guaiacol-based epoxy resin, so that the epoxy resin provides excellent heat resistance and chemical resistance for the subsequent preparation process; 4. The present invention has the advantages that an alkali neutralization reaction is used in the preparation step, which helps to reduce by-products such as hydrogen chloride generated during the reaction. The reduction of these by-products not only improves the purity of the product, but also simplifies the subsequent treatment process. In addition, during the preparation process, sodium hydroxide is used as a catalyst to effectively promote the epoxidation reaction between o-cresol-formaldehyde resin and epichlorohydrin. This catalytic effect accelerates the reaction rate, thereby improving production efficiency. 5. The advantage of the present invention is that the weakly alkaline water-soluble photosensitive resin has good solubility under alkaline conditions, which makes it easier to remove the unexposed part during the development, cleaning and other processes, thereby obtaining a clear image. This shows that the preparation improves the photosensitivity of the photosensitive resin in an alkaline environment. Combined with the advantages of the previous raw materials, this type of resin can be quickly cured under ultraviolet light to form a stable polymer structure. The fast photocuring speed not only improves production efficiency, but also helps to reduce energy consumption and pollution in the production process, in line with the concept of green environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The invention discloses a flow chart of a method for preparing a highly photosensitizing weakly alkaline water-soluble epoxy resin. DETAILED DESCRIPTION

[0020] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Without departing from the spirit and substance of the present invention, modifications or substitutions made to the methods, steps or conditions of the present invention are within the scope of the present invention.

[0021] If not specifically stated, the technical means used in the examples are conventional means known to those skilled in the art. In addition, all the raw materials used in the examples are known commercial products.

[0022] Example 1 Step (1) Preparation of epichlorohydrin Propylene and chlorine are dried, mixed in a ratio of 4:1, and introduced into a 2L high-temperature oxidation reactor, the reaction time is controlled to be 3 minutes, the generated hydrogen chloride is absorbed by a 15°C lime aqueous solution, and the oil phase is distilled under reduced pressure to obtain allyl chloride, and the prepared allyl chloride mixture is mixed with water under high-speed stirring, and chlorine is introduced to react fully, and then the product is degassed and added to the lime solution, stirred for reaction, separated from the oil phase, and distilled under reduced pressure to obtain epichlorohydrin; Step (2) Preparation of carbon fiber / epoxy resin composite material The epichlorohydrin prepared in step (1) is placed in a beaker together with 125 g of epoxy resin and 75 g of a low molecular weight polyamide curing agent, 0.5% (mass fraction) of multi-walled carbon nanotubes is accurately weighed, ultrasonically dispersed in an acetone solution for 2 h, and then added to the epoxy resin, vigorously stirred at 60° C. for 1 h, the low molecular weight polyamide is added to the epoxy resin mixed with the multi-walled carbon nanotubes, mixed evenly, and poured into the resin dipping tank of a wire winding machine for standby use, the prepreg is cut off from the wire winding machine, and left to stand at room temperature for 8 h to allow the residual acetone in the prepreg to fully volatilize, and the prepreg is pressed in an autoclave to obtain a carbon fiber / epoxy resin composite material; Step (3) Preparation of guaiacol-based bisphenol (BGF) First, the carbon fiber / epoxy resin composite material prepared in the above step (2) is prepared for use. At 50°C, epichlorohydrin, 30 g of 4-methylguaiacol and 80% phosphoric acid are added into a 100 mL three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser. Next, a 35% formaldehyde aqueous solution is slowly added dropwise using a constant pressure dropping funnel. After the addition is completed, the mixture is heated to 90°C and reacted at a constant temperature for 5 hours to obtain a golden yellow product. Finally, the mixture is washed twice with deionized water until it is neutral, and purified by column chromatography to obtain guaiacol-based bisphenol (BGF). Step (4) Preparation of guaiacol-based epoxy resin In a three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser, 13 g of the guaiacol-based bisphenol (BGF) prepared in step (3), 0.1 g of triethylbenzylammonium chloride (TBAB) and 80 mL of epichlorohydrin are added respectively, and the mixture is reacted at 90° C. for 6 h. Subsequently, the excess epichlorohydrin is removed by reduced pressure distillation, 100 mL of toluene and 4.80 g of an aqueous NaOH solution are added to the reaction system, and the reaction is continued at 90° C. for 3 h to obtain a white product. The crude product is purified by column chromatography to obtain a guaiacol-based epoxy resin. Step (5) Preparation of o-cresol-formaldehyde epoxy resin The epoxy resin cured product of step (4) was mixed with 1:0.7 phenolic acid and 0.5% oxalic acid, heated to 78°C, and then protected by nitrogen. After being kept warm for 4 hours, 15% toluene solvent was added for reaction. Then, 45% sodium hydroxide was added dropwise for 4 hours, and the mixture was kept warm with water for 1 hour. Epichlorohydrin was removed in vacuo, and 50 mL of hot distilled water was added and stirred to mix thoroughly. The water layer was separated and removed, and hot distilled water was added. The mixture was washed with water for 4 times until the value of the separated water layer was neutral. Toluene and other solvents were removed in vacuo to obtain o-cresol epoxy resin. Step (6) Synthesis of o-cresol-formaldehyde epoxy acrylate Add a polymerization inhibitor (hydroquinone) and a catalyst (carboxylate) to the o-cresol epoxy resin prepared in step (5) and a solvent accounting for 70% of the resin, stir evenly, heat the reaction to 75°C, slowly add acrylic acid dropwise using a separatory funnel, and control the addition to be completed within 2 hours. Heat the temperature to 90°C and keep it warm to obtain o-cresol epoxy acrylate; Step (7) Preparation of weakly alkaline water-soluble photosensitive resin Place the o-cresol epoxy acrylate and butyl cellosolve obtained in step (6) in a 300 mL beaker, add a polymerization inhibitor (hydroquinone) and tetramethylammonium chloride, heat to 120°C, and stir for 5 hours to make it a transparent homogeneous solution. Then, add a toluene solution of maleic anhydride. After reacting for 3.5 hours, remove the organic solvent by vacuum distillation to obtain a weakly alkaline water-soluble photosensitive resin.

[0023] Example 2 Step (1) Preparation of epichlorohydrin Propylene and chlorine are dried, mixed in a ratio of 5:2, and introduced into a 3L high-temperature oxidation reactor, the reaction time is controlled to be 2 minutes, the generated hydrogen chloride is absorbed by a 16°C lime aqueous solution, and the oil phase is distilled under reduced pressure to obtain allyl chloride, and the prepared allyl chloride mixture is mixed with water under high-speed stirring, and chlorine is introduced to react fully, and then the product is degassed and added to the lime solution, stirred for reaction, separated from the oil phase, and distilled under reduced pressure to obtain epichlorohydrin; Step (2) Preparation of carbon fiber / epoxy resin composite material The epichlorohydrin prepared in step (1) is placed in a beaker together with 125 g of epoxy resin and 75 g of a low molecular weight polyamide curing agent, 0.5% (mass fraction) of multi-walled carbon nanotubes is accurately weighed, ultrasonically dispersed in an acetone solution for 2 h, and then added to the epoxy resin, vigorously stirred at 60° C. for 1 h, the low molecular weight polyamide is added to the epoxy resin mixed with the multi-walled carbon nanotubes, mixed evenly, and poured into the resin dipping tank of a wire winding machine for standby use, the prepreg is cut off from the wire winding machine, and left to stand at room temperature for 8 h to allow the residual acetone in the prepreg to fully volatilize, and the prepreg is pressed in an autoclave to obtain a carbon fiber / epoxy resin composite material; Step (3) Preparation of guaiacol-based bisphenol (BGF) First, the carbon fiber / epoxy resin composite material prepared in the above step (2) is prepared for use. At 50° C., epichlorohydrin, 30 g of 4-methylguaiacol and 80% phosphoric acid are added into a 100 mL three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser. Next, a 35% formaldehyde aqueous solution is slowly added dropwise using a constant pressure dropping funnel. After the addition is completed, the solution is heated to 90° C. and reacted at a constant temperature for 5 hours to obtain a golden yellow product. Finally, the product is washed twice with deionized water until it is neutral, and purified by column chromatography to obtain guaiacol-based bisphenol (BGF). Step (4) Preparation of guaiacol-based epoxy resin In a three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser, 13 g of the guaiacol-based bisphenol (BGF) prepared in step (3), 0.1 g of triethylbenzylammonium chloride (TBAB) and 80 mL of epichlorohydrin are added respectively, and the mixture is reacted at 90° C. for 6 h. Subsequently, the excess epichlorohydrin is removed by reduced pressure distillation, 100 mL of toluene and 4.80 g of an aqueous NaOH solution are added to the reaction system, and the reaction is continued at 90° C. for 3 h to obtain a white product. The crude product is purified by column chromatography to obtain a guaiacol-based epoxy resin. Step (5) Preparation of o-cresol-formaldehyde epoxy resin The epoxy resin cured product of step (4) was mixed with 2:1 phenolic acid and 1% oxalic acid, heated to 75°C, and then protected with nitrogen. After being kept warm for 5 hours, 11% toluene solvent was added for reaction. Then, 40% sodium hydroxide was added dropwise for 4 hours, and the mixture was kept warm with water for 1 hour. Epichlorohydrin was removed in vacuo, and 45 mL of hot distilled water was added and stirred to mix thoroughly. The water layer was separated and removed, and hot distilled water was added. The mixture was washed with water for 4 times until the value of the separated water layer was neutral. The toluene and other solvents were removed in vacuo to obtain o-cresol epoxy resin. Step (6) Synthesis of o-cresol-formaldehyde epoxy acrylate Add a polymerization inhibitor (hydroquinone) and a catalyst (carboxylate) to the o-cresol epoxy resin prepared in step (5) and a solvent accounting for 65% of the resin, stir evenly, heat the reaction to 70°C, slowly add acrylic acid dropwise using a separatory funnel, and control the addition to be completed within 1.5 hours. Heat the temperature to 85°C and keep it warm to obtain o-cresol epoxy acrylate; Step (7) Preparation of weakly alkaline water-soluble photosensitive resin Place the o-cresol epoxy acrylate and butyl cellosolve obtained in step (6) in a 300 mL beaker, add a polymerization inhibitor (hydroquinone) and tetramethylammonium chloride, heat to 110°C, and stir for 5 hours to make it a transparent homogeneous solution. Then, add a toluene solution of maleic anhydride. After reacting for 4 hours, remove the organic solvent by vacuum distillation to obtain a weakly alkaline water-soluble photosensitive resin.

[0024] Example 3 Step (1) Preparation of epichlorohydrin Propylene and chlorine are dried, mixed in a ratio of 5:3, and introduced into a 4L high-temperature oxidation reactor, the reaction time is controlled to be 1 minute, the generated hydrogen chloride is absorbed by an 18°C ​​lime water solution, and the oil phase is distilled under reduced pressure to obtain allyl chloride, and the prepared allyl chloride mixture is mixed with water under high-speed stirring, and chlorine is introduced to react fully, and then the product is degassed and added to the lime solution, stirred for reaction, separated from the oil phase, and distilled under reduced pressure to obtain epichlorohydrin; Step (2) Preparation of carbon fiber / epoxy resin composite material The epichlorohydrin prepared in step (1) is placed in a beaker together with 125 g of epoxy resin and 75 g of a low molecular weight polyamide curing agent, 0.5% (mass fraction) of multi-walled carbon nanotubes is accurately weighed, ultrasonically dispersed in an acetone solution for 2 h, and then added to the epoxy resin, vigorously stirred at 60° C. for 1 h, the low molecular weight polyamide is added to the epoxy resin mixed with the multi-walled carbon nanotubes, mixed evenly, and poured into the resin dipping tank of a wire winding machine for standby use, the prepreg is cut off from the wire winding machine, and left to stand at room temperature for 8 h to allow the residual acetone in the prepreg to fully volatilize, and the prepreg is pressed in an autoclave to obtain a carbon fiber / epoxy resin composite material; Step (3) Preparation of guaiacol-based bisphenol (BGF) First, the carbon fiber / epoxy resin composite material prepared in the above step (2) is prepared for use. At 50° C., epichlorohydrin, 30 g of 4-methylguaiacol and 80% phosphoric acid are added into a 100 mL three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser. Next, a 35% formaldehyde aqueous solution is slowly added dropwise using a constant pressure dropping funnel. After the addition is completed, the solution is heated to 90° C. and reacted at a constant temperature for 5 hours to obtain a golden yellow product. Finally, the product is washed twice with deionized water until it is neutral, and purified by column chromatography to obtain guaiacol-based bisphenol (BGF). Step (4) Preparation of guaiacol-based epoxy resin In a three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser, 13 g of the guaiacol-based bisphenol (BGF) prepared in step (3), 0.1 g of triethylbenzylammonium chloride (TBAB) and 80 mL of epichlorohydrin are added respectively, and the mixture is reacted at 90° C. for 6 h. Subsequently, the excess epichlorohydrin is removed by reduced pressure distillation, 100 mL of toluene and 4.80 g of an aqueous NaOH solution are added to the reaction system, and the reaction is continued at 90° C. for 3 h to obtain a white product. The crude product is purified by column chromatography to obtain a guaiacol-based epoxy resin. Step (5) Preparation of o-cresol-formaldehyde epoxy resin Take the epoxy resin cured product of step (4) and 1:2 phenolic acid and 2% oxalic acid, heat to 80°C, then protect with nitrogen, keep warm for 6 hours, then add 12% toluene solvent to react, then add 44% sodium hydroxide dropwise for 5 hours, keep warm with water for 1 hour, vacuum remove epichlorohydrin, add 50 mL hot distilled water and stir to mix thoroughly, separate and remove the water layer, add hot distilled water, repeatedly wash with water 4 times until the value of the separated water layer is neutral, vacuum remove toluene and other solvents to obtain o-cresol epoxy resin; Step (6) Synthesis of o-cresol-formaldehyde epoxy acrylate Add a polymerization inhibitor (hydroquinone) and a catalyst (carboxylate) to the o-cresol epoxy resin prepared in step (5) and a solvent accounting for 68% of the resin, stir evenly, heat the reaction to 73°C, slowly add acrylic acid dropwise using a separatory funnel, and control the addition to be completed within 2 hours. Heat the temperature to 88°C and keep it warm to obtain o-cresol epoxy acrylate; Step (7) Preparation of weakly alkaline water-soluble photosensitive resin Place the o-cresol epoxy acrylate and butyl cellosolve obtained in step (6) in a 300 mL beaker, add a polymerization inhibitor (hydroquinone) and tetramethylammonium chloride, heat to 100°C, and stir for 5 hours to make it a transparent homogeneous solution. Then, add a toluene solution of maleic anhydride. After reacting for 5 hours, remove the organic solvent by vacuum distillation to obtain a weakly alkaline water-soluble photosensitive resin.

[0025] Example 4 Step (1) Preparation of epichlorohydrin Propylene and chlorine are dried, mixed in a ratio of 6:3, and introduced into a 5L high-temperature oxidation reactor, the reaction time is controlled to be 1 minute, the generated hydrogen chloride is absorbed by a 20°C lime aqueous solution, and the oil phase is distilled under reduced pressure to obtain allyl chloride, and the prepared allyl chloride mixture is mixed with water under high-speed stirring, and chlorine is introduced to react fully, and then the product is degassed and added to the lime solution, stirred for reaction, separated from the oil phase, and distilled under reduced pressure to obtain epichlorohydrin; Step (2) Preparation of carbon fiber / epoxy resin composite material The epichlorohydrin prepared in step (1) is placed in a beaker together with 125 g of epoxy resin and 75 g of a low molecular weight polyamide curing agent, 0.5% (mass fraction) of multi-walled carbon nanotubes is accurately weighed, ultrasonically dispersed in an acetone solution for 2 h, and then added to the epoxy resin, vigorously stirred at 60° C. for 1 h, the low molecular weight polyamide is added to the epoxy resin mixed with the multi-walled carbon nanotubes, mixed evenly, and poured into the resin dipping tank of a wire winding machine for standby use, the prepreg is cut off from the wire winding machine, and left to stand at room temperature for 8 h to allow the residual acetone in the prepreg to fully volatilize, and the prepreg is pressed in an autoclave to obtain a carbon fiber / epoxy resin composite material; Step (3) Preparation of guaiacol-based bisphenol (BGF) First, the carbon fiber / epoxy resin composite material prepared in the above step (2) is prepared for use. At 50° C., epichlorohydrin, 30 g of 4-methylguaiacol and 80% phosphoric acid are added into a 100 mL three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser. Next, a 35% formaldehyde aqueous solution is slowly added dropwise using a constant pressure dropping funnel. After the addition is completed, the solution is heated to 90° C. and reacted at a constant temperature for 5 hours to obtain a golden yellow product. Finally, the product is washed twice with deionized water until it is neutral, and purified by column chromatography to obtain guaiacol-based bisphenol (BGF). Step (4) Preparation of guaiacol-based epoxy resin In a three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser, 13 g of the guaiacol-based bisphenol (BGF) prepared in step (3), 0.1 g of triethylbenzylammonium chloride (TBAB) and 80 mL of epichlorohydrin are added respectively, and the mixture is reacted at 90° C. for 6 h. Subsequently, the excess epichlorohydrin is removed by reduced pressure distillation, 100 mL of toluene and 4.80 g of an aqueous NaOH solution are added to the reaction system, and the reaction is continued at 90° C. for 3 h to obtain a white product. The crude product is purified by column chromatography to obtain a guaiacol-based epoxy resin. Step (5) Preparation of o-cresol-formaldehyde epoxy resin Take the epoxy resin cured product of step (4) and 1.5:1 phenolic acid and 1.5% oxalic acid, heat to 90°C, then protect with nitrogen, keep warm for 5.5 hours, then add 14% toluene solvent to react, then add 43% sodium hydroxide dropwise for 2 hours, keep warm with water for 1.5 hours, vacuum remove epichlorohydrin, add 48 mL hot distilled water and stir to mix thoroughly, separate and remove the water layer, add hot distilled water, repeatedly wash with water 4 times until the value of the separated water layer is neutral, vacuum remove toluene and other solvents to obtain o-cresol epoxy resin; Step (6) Synthesis of o-cresol-formaldehyde epoxy acrylate Add a polymerization inhibitor (hydroquinone) and a catalyst (carboxylate) to the o-cresol epoxy resin prepared in step (5) and a solvent accounting for 66% of the resin, stir evenly, heat the reaction to 76°C, slowly add acrylic acid dropwise using a separatory funnel, and control the addition to be completed within 1.5 hours. Heat the temperature to 89°C and keep warm to obtain o-cresol epoxy acrylate; Step (7) Preparation of weakly alkaline water-soluble photosensitive resin Place the o-cresol epoxy acrylate and butyl cellosolve obtained in step (6) in a 300 mL beaker, add a polymerization inhibitor (hydroquinone) and tetramethylammonium chloride, raise the temperature to 95°C, and stir for 5 hours to make it a transparent homogeneous solution. Then, add a toluene solution of maleic anhydride. After reacting for 4.5 hours, remove the organic solvent by vacuum distillation to obtain a weakly alkaline water-soluble photosensitive resin.

[0026] Comparative Example 1 Step (1) Preparation of carbon fiber / epoxy resin composite material 125g of epoxy resin and 75g of low molecular weight polyamide curing agent are put into a beaker, 0.5% (mass fraction) of multi-walled carbon nanotubes are accurately weighed, ultrasonically dispersed in an acetone solution for 2h, and then added to the epoxy resin, vigorously stirred at 60°C for 1h, the low molecular weight polyamide is added to the epoxy resin mixed with the multi-walled carbon nanotubes, mixed evenly, and poured into the dipping tank of the winding machine for standby use, the prepreg is cut off from the winding machine, and left to stand at room temperature for 8h to fully volatilize the residual acetone in the prepreg, and the prepreg is pressed in an autoclave to obtain a carbon fiber / epoxy resin composite material; Step (2) Preparation of guaiacol-based bisphenol (BGF) First, the carbon fiber / epoxy resin composite material prepared in the above step (1) is prepared for use. At 50° C., epichlorohydrin, 30 g of 4-methylguaiacol and 80% phosphoric acid are respectively added into a 100 mL three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser. Next, a 35% formaldehyde aqueous solution is slowly added dropwise using a constant pressure dropping funnel. After the addition is completed, the mixture is heated to 90° C. and reacted at a constant temperature for 5 hours to obtain a golden yellow product. Finally, the mixture is washed twice with deionized water until it is neutral, and purified by column chromatography to obtain guaiacol-based bisphenol (BGF). Step (3) Preparation of guaiacol-based epoxy resin In a three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser, 13 g of the guaiacol-based bisphenol (BGF) prepared in step (2), 0.1 g of triethylbenzylammonium chloride (TBAB) and 80 mL of epichlorohydrin were added respectively, and the mixture was reacted at 90° C. for 6 h. Subsequently, the excess epichlorohydrin was removed by reduced pressure distillation, 100 mL of toluene and 4.80 g of an aqueous NaOH solution were added to the reaction system, and the reaction was continued at 90° C. for 3 h to obtain a white product. The crude product was purified by column chromatography to obtain a guaiacol-based epoxy resin. Step (4) Preparation of o-cresol-formaldehyde epoxy resin Take the epoxy resin cured product of step (3) and 1:2 phenolic acid and 2% oxalic acid, heat to 80°C, then protect with nitrogen, keep warm for 6 hours, then add 12% toluene solvent to react, then add 44% sodium hydroxide dropwise for 5 hours, keep warm with water for 1 hour, vacuum remove epichlorohydrin, add 50 mL hot distilled water and stir to mix thoroughly, separate and remove the water layer, add hot distilled water again, repeatedly wash with water 4 times until the value of the separated water layer is neutral, vacuum remove toluene and other solvents to obtain o-cresol epoxy resin; Step (5) Synthesis of o-cresol epoxy acrylate Add a polymerization inhibitor (hydroquinone) and a catalyst (carboxylate) to the o-cresol epoxy resin prepared in step (4) and a solvent accounting for 68% of the resin, stir evenly, heat the reaction to 73°C, slowly add acrylic acid dropwise using a separatory funnel, and control the addition to be completed within 2 hours. Heat the temperature to 88°C and keep it warm to obtain o-cresol epoxy acrylate; Step (6) Preparation of weakly alkaline water-soluble photosensitive resin Place the o-cresol epoxy acrylate and butyl cellosolve obtained in step (5) in a 300 mL beaker, add a polymerization inhibitor (hydroquinone) and tetramethylammonium chloride, raise the temperature to 85°C, and stir for 5 hours to make it a transparent homogeneous solution. Then, add a toluene solution of maleic anhydride. After reacting for 2.5 hours, remove the organic solvent by vacuum distillation to obtain a weakly alkaline water-soluble photosensitive resin.

[0027] Comparative Example 2

[0028] Step (1) Preparation of guaiacol-based bisphenol (BGF) At 50°C, epichlorohydrin, 30g 4-methylguaiacol and 80% phosphoric acid were added into a 100mL three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser. Next, a 35% formaldehyde aqueous solution was slowly added dropwise using a constant pressure dropping funnel. After the addition was completed, the mixture was heated to 90°C and kept at a constant temperature for 5h to obtain a golden yellow product. Finally, the product was washed twice with deionized water until it was neutral, and purified by column chromatography to obtain guaiacol-based bisphenol (BGF). Step (2) Preparation of o-cresol-formaldehyde epoxy resin The epoxy resin cured product of step (1) was mixed with 1.5:1 phenolic acid and 1.5% oxalic acid, heated to 90°C, and then protected with nitrogen. After the mixture was kept warm for 5.5 hours, 14% toluene solvent was added for reaction. Then, 43% sodium hydroxide was added dropwise for 2 hours, and the mixture was kept warm with water for 1.5 hours. Epichlorohydrin was removed in vacuo, 48 mL of hot distilled water was added and stirred to mix thoroughly, the water layer was separated and removed, and hot distilled water was added. The mixture was washed with water for 4 times until the value of the separated water layer was neutral. Toluene and other solvents were removed in vacuo to obtain o-cresol epoxy resin. Step (3) Synthesis of o-cresol epoxy acrylate Add a polymerization inhibitor (hydroquinone) and a catalyst (carboxylate) to the o-cresol epoxy resin prepared in step (2) and a solvent accounting for 66% of the resin, stir evenly, heat the reaction to 76°C, slowly add acrylic acid dropwise using a separatory funnel, and control the addition to be completed within 1.5 hours. Heat the temperature to 89°C and keep warm to obtain o-cresol epoxy acrylate; Step (4) Preparation of weakly alkaline water-soluble photosensitive resin Place the o-cresol epoxy acrylate and butyl cellosolve obtained in step (3) in a 300 mL beaker, add a polymerization inhibitor (hydroquinone) and tetramethylammonium chloride, raise the temperature to 80°C, and stir for 5 hours to make it a transparent homogeneous solution. Then add a toluene solution of maleic anhydride, take samples every 33 minutes to test the acid value, react for 3 hours, and use reduced pressure distillation to remove the organic solvent to obtain a weakly alkaline water-soluble photosensitive resin.

[0029] Comparison of detection experiments: The highly photosensitivity weak base water-soluble epoxy resins obtained in Examples 1 to 4 and Comparative Example Products 1 and 2 were tested. The specific testing method is as follows: Determination of acid value and characterization of reaction conversion rate The acid value is the mass (mg) of KOH consumed by the acidic components in each gram of sample. Accurately weigh 1.0g~1.5g of sample into a 250mL conical flask, add 10mL acetone solution to dissolve and 10mL pyridine / water = 2:1 hydrolysis solution to hydrolyze the excess anhydride, and leave it for 10 minutes. Add 3~5 drops of 1% phenolphthalein indicator, and titrate with potassium hydroxide-ethanol standard solution until pink appears and does not fade within 15 seconds. Perform a blank test.

[0030] Infrared spectroscopy The synthesized weakly alkaline water-soluble epoxy resin sample was prepared into a KBr solid pellet or an acetone solution and coated on a NaCl prism to form a thin film. The cured film was recorded using a Vector33 Fourier transform infrared spectrometer from Bruker, Germany.

[0031] Table 1 Determination of the effect of acid value on conversion rate at different reaction times

[0032] As shown in Table 1, Example 3 is the best and Comparative Example 1 is the worst. In Example 3, its reaction time is 5h, and the conversion rate is as high as 95.36%, indicating that the longer the reaction time of maleic anhydride-modified o-cresol epoxy acrylate under the influence of catalyst tetramethylammonium chloride, the higher the conversion rate, and saturation is reached when the reaction is 5h. The improvement of the conversion rate means that the reaction is more complete, thereby improving the curing performance of the weakly alkaline water-soluble photosensitive resin. The introduction of maleic anhydride can enhance the crosslinking density of o-cresol epoxy acrylate through chemical reaction, so that the cured coating or material has higher hardness and better acid and alkali resistance.

[0033] Table 2 Effect of different temperatures on reaction conversion

[0034] It can be seen from Table 2 that Example 3 has the highest conversion rate and the highest performance. The high conversion rate is accompanied by an accelerated reaction rate, indicating that the conversion rate of the resin increases with increasing temperature. When the reaction temperature reaches 120°C, the conversion rate reaches a peak value and the reaction rate is the fastest. The increase in conversion rate can make the weakly alkaline water-soluble photosensitive resin have stronger photocuring behavior and better photosensitivity in practical applications, and has good application prospects in the field of photoresists.

[0035] Table 3 Infrared spectrum analysis conversion rate test

[0036] As shown in Table 3, Example 3 has the highest conversion rate, and the irradiation time is 22s. After the photocuring system is irradiated with UV (ultraviolet light) for 15s, the conversion rate has exceeded 80%, indicating that the photosensitivity of the synthesized alkali-soluble photosensitive resin is good, and it reaches saturation at 22s, and the photosensitivity is the best. After irradiation for 22s, the conversion rate of the system reaches 84.78%. Even if the irradiation time is extended, the effect on the conversion rate is not obvious. With the polymerization of the prepolymer, the molecular chain of the molecule increases rapidly, the cross-linking density increases rapidly, and some photoactive groups are blocked, causing the reaction rate to become slower and slower. This characteristic of the photocuring reaction requires that its application should pay more attention to the initial stage of curing. It is not economical to try to increase the degree of curing by extending the curing time. Therefore, when the irradiation time is 22s, the photosensitivity of the weakly alkaline water-soluble photosensitive resin is most suitable.

[0037] This specific embodiment is merely an explanation of the present invention, and it is not a limitation of the present invention. A person skilled in the art can make non-creative modifications to the present embodiment as needed after reading this specification. However, as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

Claims

1. A method for preparing a highly photosensitizing weakly alkaline water-soluble epoxy resin, characterized in that: include: Preparation of epichlorohydrin, preparation of carbon fiber / epoxy resin composites, preparation of guaiacol-based bisphenol (BGF), preparation of guaiacol-based epoxy resin, preparation of o-cresol-formaldehyde epoxy resin, synthesis of o-cresol-formaldehyde epoxy acrylate, preparation of weak base water-soluble photosensitive resin.

2. The preparation of the highly photosensitivity weak base water-soluble epoxy resin according to claim 1, characterized in that: Step (1) Preparation of epichlorohydrin Propylene and chlorine are dried, mixed in a certain amount ratio, and introduced into a high-temperature chlorination reactor, and the generated hydrogen chloride is absorbed by lime water solution, and the oil phase is distilled under reduced pressure to obtain allyl chloride, and the prepared allyl chloride mixture is mixed with water under high-speed stirring, and chlorine is introduced to react fully, and then the product is degassed and added to the lime solution, stirred for reaction, separated from the oil phase, and distilled under reduced pressure to obtain epichlorohydrin; Step (2) Preparation of carbon fiber / epoxy resin composite material The epichlorohydrin prepared in step (1) is placed in a beaker together with the epoxy resin and the low molecular weight polyamide curing agent, multi-walled carbon nanotubes are weighed, ultrasonically dispersed in an acetone solution, and then added to the epoxy resin, and vigorously stirred, and the low molecular weight polyamide is added to the epoxy resin mixed with the multi-walled carbon nanotubes, and after mixing evenly, the mixture is poured into the dipping tank of the winding machine for standby use, the prepreg is cut and removed from the winding machine, and allowed to stand at room temperature to allow the residual acetone in the prepreg to fully volatilize, and the prepreg is pressed in an autoclave to obtain a carbon fiber / epoxy resin composite material; Step (3) Preparation of guaiacol-based bisphenol (BGF) First, the carbon fiber / epoxy resin composite material prepared in the above step (2) is prepared for use. At a certain temperature, epichlorohydrin, 4-methylguaiacol and phosphoric acid are respectively added into a three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser. Next, a formaldehyde aqueous solution is slowly added dropwise using a constant pressure dropping funnel. After the addition is completed, a golden yellow product is obtained by heating and constant temperature reaction. Finally, the product is washed with deionized water for several times until it is neutral, and purified by column chromatography to obtain guaiacol-based bisphenol (BGF); Step (4) Preparation of guaiacol-based epoxy resin In a three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser, the guaiacol-based bisphenol (BGF), triethylbenzylammonium chloride (TBAB) and epichlorohydrin prepared in step (3) are added respectively, and reacted at a certain temperature, and the excess epichlorohydrin is removed by vacuum distillation, and toluene and an aqueous NaOH solution are added to the reaction system, and the reaction is continued to obtain a white product, and the crude product is purified by column chromatography to obtain a guaiacol-based epoxy resin; Step (5) Preparation of o-cresol epoxy resin A certain amount of the epoxy resin cured product of step (4) is taken together with phenolic formaldehyde and oxalic acid, and heated under nitrogen protection. After the heat preservation is completed, a small amount of toluene solvent is added for reaction. Then, sodium hydroxide is added, and the mixture is kept warm with water. Epichlorohydrin is removed in a vacuum. Hot distilled water is added and stirred to fully mix. The aqueous layer is separated and removed. Hot distilled water is added again, and the separated aqueous layer is repeatedly washed with water until the pH value of the separated aqueous layer is neutral. Toluene and other solvents are removed in a vacuum to obtain o-cresol formaldehyde epoxy resin. Step (6) Synthesis of o-cresol-formaldehyde epoxy acrylate Adding a polymerization inhibitor (hydroquinone) and a catalyst (carboxylate) to the o-cresol epoxy resin and the solvent in step (5) at the same time, stirring evenly, slowly adding acrylic acid dropwise using a separatory funnel after the reaction temperature rises, and after the addition is complete, raising the temperature and maintaining the temperature until the difference between the measured acid value and the initial acid value is small, thereby obtaining o-cresol epoxy acrylate; Step (7) Preparation of weakly alkaline water-soluble photosensitive resin Take appropriate amounts of o-cresol epoxy acrylate and butyl cellosolve from step (6), add a polymerization inhibitor (hydroquinone) and tetramethylammonium chloride, stir to make a transparent homogeneous solution, then add a toluene solution of maleic anhydride, slowly raise the temperature to the set reaction temperature, react for a period of time, and use reduced pressure distillation to remove the organic solvent to obtain a weakly alkaline water-soluble photosensitive resin.

3. The preparation of a highly photosensitivity weak base water-soluble epoxy resin according to claim 2, characterized in that: Step (1) Preparation of epichlorohydrin After drying, propylene and chlorine are mixed in a ratio of 4-10:1-5 and introduced into a 1-5L high-temperature oxidation reactor, the reaction time is controlled to be 1-3 minutes, the generated hydrogen chloride is absorbed by a 15-20°C lime aqueous solution, and the oil phase is distilled under reduced pressure to obtain allyl chloride, and the prepared allyl chloride mixture is mixed with water under high-speed stirring, chlorine is introduced and fully reacted, and then the product is degassed and added to the lime solution, stirred for reaction, separated from the oil phase, and distilled under reduced pressure to obtain epichlorohydrin.

4. The preparation of a highly photosensitivity weak base water-soluble epoxy resin according to claim 3, characterized in that: Step (2) Preparation of carbon fiber / epoxy resin composite material The epichlorohydrin prepared in step (1) is placed in a beaker together with 125-150 g of epoxy resin and 75-80 g of a low molecular weight polyamide curing agent. 0.5-0.6% (mass fraction) of multi-walled carbon nanotubes are accurately weighed and ultrasonically dispersed in an acetone solution for 2-3 hours, and then added to the epoxy resin. The mixture is vigorously stirred at 60-65° C. for 1-2 hours. The low molecular weight polyamide is added to the epoxy resin mixed with the multi-walled carbon nanotubes, and after mixing evenly, the mixture is poured into a resin dipping tank of a wire winding machine for standby use. The prepreg is cut and removed from the wire winding machine, and allowed to stand at room temperature for 8-10 hours to allow the residual acetone in the prepreg to fully volatilize. The prepreg is pressed in an autoclave to obtain a carbon fiber / epoxy resin composite material.

5. The preparation of a highly photosensitivity weak base water-soluble epoxy resin according to claim 4, characterized in that: Step (3) Preparation of guaiacol-based bisphenol (BGF) First, the carbon fiber / epoxy resin composite material prepared in the above step (2) is prepared for use. At 50-60° C., epichlorohydrin, 30-35 g of 4-methylguaiacol and 80-90% phosphoric acid are respectively added into a 95-100 mL three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser. Next, a 35-40% formaldehyde aqueous solution is slowly added dropwise using a constant pressure dropping funnel. After the addition is completed, the mixture is heated to 90-92° C. and reacted at a constant temperature for 5-8 hours to obtain a golden yellow product. Finally, the mixture is washed with deionized water for 2-3 times until it is neutral, and purified by column chromatography to obtain guaiacol-based bisphenol BGF.

6. The preparation of a highly photosensitivity weak base water-soluble epoxy resin according to claim 5, characterized in that: Step (4) Preparation of guaiacol-based epoxy resin In a three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser, 13-15 g of the guaiacol-based bisphenol (BGF) prepared in step (3), 0.1-0.3 g of triethylbenzylammonium chloride (TBAB) and 80-100 mL of epichlorohydrin are added respectively, and the mixture is reacted at 90-100° C. for 6-7 hours. Subsequently, the excess epichlorohydrin is removed by reduced pressure distillation, 100-120 mL of toluene and 4.80-5.00 g of a NaOH aqueous solution are added to the reaction system, and the mixture is reacted at 90-100° C. for 3-4 hours to obtain a white product. The crude product is purified by column chromatography to obtain a guaiacol-based epoxy resin.

7. The preparation of a highly photosensitivity weak base water-soluble epoxy resin according to claim 6, characterized in that: Step (5) Preparation of o-cresol epoxy resin The epoxy resin cured product prepared in step (4) is mixed with 1-2:0-2 phenolic acid and 0.5-2% oxalic acid, and heated to 75-100°C, and then protected by nitrogen. After keeping warm for 4-6 hours, 10-15% toluene solvent is added for reaction. Next, 40-45% sodium hydroxide is added dropwise for 2-4 hours, and the mixture is kept warm with water for 1-2 hours. Epichlorohydrin is removed in vacuo, and 45-50 mL of hot distilled water is added and stirred to mix thoroughly. The aqueous layer is separated and removed, and hot distilled water is added. The mixture is washed repeatedly with water for 4-5 times until the pH value of the separated aqueous layer is neutral. Toluene and other solvents are removed in vacuo to obtain o-cresol epoxy resin.

8. The preparation of a highly photosensitivity weak base water-soluble epoxy resin according to claim 7, characterized in that: Step (6) Synthesis of o-cresol-formaldehyde epoxy acrylate Add a polymerization inhibitor (hydroquinone) and a catalyst (carboxylate) to the o-cresol epoxy resin prepared in step (5) and an organic solvent accounting for 65-70% of the resin, stir evenly, heat the reaction to 70-75°C, slowly add acrylic acid dropwise using a separatory funnel, and control the addition to be completed within 1.5-2 hours. Heat the temperature to 85-90°C and keep warm to obtain o-cresol epoxy acrylate.

9. The preparation of a highly photosensitivity weak base water-soluble epoxy resin according to claim 8, characterized in that: Step (7) Preparation of weakly alkaline water-soluble photosensitive resin Place the o-cresol epoxy acrylate and butyl cellosolve obtained in step (6) in a 250-300 mL beaker, add a polymerization inhibitor (hydroquinone) and tetramethylammonium chloride, heat to 80-120° C., stir for 4-6 hours to make it a transparent homogeneous solution, then add a toluene solution of maleic anhydride, react for 2.5-6 hours, and then use reduced pressure distillation to remove the organic solvent to obtain a weakly alkaline water-soluble photosensitive resin.

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