Phenol epoxy resin and method for producing the same

Abstract

To provide a phenol epoxy resin and a method for producing the same.SOLUTION: A method for producing a phenol epoxy resin includes: adding cardanol and vanillin to a reaction tank; heating the reaction tank, adding an acidic catalyst thereto when a temperature reaches 60°C to 90°C, thereby conducting a polycondensation reaction of cardanol and vanillin, and forming a phenol resin; mixing the phenol resin and epichlorohydrin and conducting a substitution reaction at a temperature of 55°C to 70°C, and thereby forming a phenol epoxy resin. The vanillin is a limited reagent. An acidic coefficient pKa in water at 25°C of the acidic catalyst is less than 3.1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a phenolic epoxy resin and a method for producing the same, and more particularly to a phenolic epoxy resin produced from a biomass material and a method for producing the same. [Background technology]

[0002] Thermosetting epoxy resins have excellent comprehensive properties and are widely used in coatings, adhesives, encapsulating adhesives and composite materials. However, the main source of traditional epoxy resins is petrochemicals.

[0003] For example, bisphenol epoxy resin, which currently has the highest yield, has mature biomass technology for epichlorohydrin, the main raw material for producing bisphenol epoxy resin. However, the raw material for bisphenol is still produced by decomposing petroleum products. Furthermore, bisphenol is known to be biologically toxic, and many countries have explicitly banned the use of bisphenol in materials that come into contact with food or the human body.

[0004] Therefore, faced with the shortage of petroleum, increasing environmental awareness, and limited applications due to biological toxicity, research departments are conducting research into monomers that can be used to replace bisphenols in order to overcome the above problems and produce environmentally friendly products made entirely from biomass materials.

[0005] Therefore, overcoming the above-mentioned drawbacks by improving the material structure and producing epoxy resins using biomass materials as raw materials is an important task for this project. Summary of the Invention [Problem to be solved by the invention]

[0006] The technical problem to be solved by the present invention is to provide a phenolic epoxy resin and a method for producing the same, which address the shortcomings of the prior art. [Means for solving the problem]

[0007] To solve the above technical problems, one technical solution adopted by the present invention is to provide a method for producing phenolic epoxy resin. The method for producing phenolic epoxy resin includes adding cardanol and vanillin to a reaction tank, heating the reaction tank, and adding an acidic catalyst when the temperature reaches 60°C to 90°C to carry out a polycondensation reaction between the cardanol and vanillin to form a phenolic resin. At a temperature of 55°C to 70°C, the phenolic resin is mixed with epichlorohydrin to carry out a substitution reaction to form the phenolic epoxy resin. Vanillin is the limiting reagent. The acidic catalyst has an acidity constant (pKa) of less than 3.1 in water at 25°C.

[0008] In one embodiment, the acidic catalyst has an acidity coefficient pKa in water at 25° C. of −2 to 1.5.

[0009] In one embodiment, the amount of the acid catalyst added is 0.25 parts by weight to 1 part by weight, where the total weight of cardanol and vanillin is 100 parts by weight.

[0010] In one embodiment, the acid catalyst is methanesulfonic acid.

[0011] In one embodiment, the method for producing a phenolic epoxy resin further comprises quenching the polycondensation reaction after forming the phenolic resin by adding an alkaline solution to the reaction tank.

[0012] In one embodiment, the alkaline solution is aqueous sodium hydroxide.

[0013] In one embodiment, after adding the alkaline solution, an acidic substance is added so as to control the pH of the phenolic resin to 6.5 to 7.5.

[0014] In one embodiment, the acidic substance is oxalic acid.

[0015] In one embodiment, the method for producing a phenolic resin includes adding an acidic substance and then adding an extraction solvent to extract the phenolic resin, and then mixing the phenolic resin with epichlorohydrin to carry out a substitution reaction, and the extraction solvent is selected from the group consisting of ethyl acetate, toluene, and methyl isobutyl ketone.

[0016] In one embodiment, the substitution reaction is carried out by mixing the phenolic resin, epichlorohydrin, and a surfactant that is an alcohol ether solvent.

[0017] In one embodiment, the weight average molecular weight of the phenolic resin is 4,000 g / mol to 10,000 g / mol.

[0018] In one embodiment, the hydroxyl equivalent of the phenolic resin is 200 g / equivalent to 250 g / equivalent.

[0019] Another technical solution adopted by the present invention to solve the above technical problems is to provide a phenolic epoxy resin, which is produced by the above method. [Effects of the Invention]

[0020] As an advantageous effect of the present invention, the phenolic epoxy resin and the production method thereof according to the present invention can produce a phenolic epoxy resin made from biomass materials, which can be used as an alternative to conventional petrochemical-derived phenolic epoxy resins, by virtue of the technical features of "adding cardanol and vanillin to a reaction tank" and "the acidity coefficient pKa of the acidic catalyst in water at 25°C is less than 3.1." [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a flowchart of a method for producing a phenolic epoxy resin according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing the reaction mechanism between the phenolic resin of the present invention and epichlorohydrin. DETAILED DESCRIPTION OF THE INVENTION

[0022] To better understand the features and technical contents of the present invention, please refer to the following detailed description of the present invention and the accompanying drawings, which are provided for reference and explanation only and are not intended to limit the scope of the present invention.

[0023] The following describes "phenolic epoxy resins and methods for producing the same" according to certain specific embodiments of the present invention, and those skilled in the art will be able to understand the advantages and benefits of the present invention based on the disclosure herein. The present invention can be implemented or applied in other different specific embodiments, and various modifications and changes can be made to the details herein based on different perspectives and applications without departing from the concept of the present invention. As previously explained, the accompanying drawings are for simple schematic illustrations and are not drawn to scale. The technical content of the present invention will be described in more detail based on the following embodiments, but the disclosed content does not limit the scope of protection of the present invention. Furthermore, the term "or" used in the present specification may include any one or more combinations of the relevant listed items, depending on the actual situation.

[0024] To overcome the above-mentioned problems of raw material toxicity and shortage of petrochemical raw materials, the present invention provides a phenolic epoxy resin made entirely from biomass materials by selecting synthetic monomers, which contributes to environmental protection. After selecting a specific biomass material, the synthesis process needs to be adjusted according to its characteristics.

[0025] Specifically, in the present invention, cardanol and vanillin are used as raw materials, and a polycondensation reaction is carried out to synthesize a phenolic resin (steps S1 to S5), followed by a substitution reaction of the phenolic resin with epichlorohydrin (steps S6 to S10), thereby obtaining a phenolic epoxy resin produced entirely from biomass materials. Therefore, the phenolic epoxy resin of the present invention can be used as a substitute for conventional bisphenol A-type phenolic epoxy resins.

[0026] Both cardanol and vanillin are derived from biomass materials, with cardanol being used as a replacement for currently commonly used phenols (e.g., bisphenol A), and vanillin being used as a replacement for highly toxic formaldehyde. Thus, the structural formula of the phenolic resin of the present invention may be represented as follows: [ka] Here, n is an integer from 5 to 25.

[0027] As shown in Figure 1, the method for producing a phenolic epoxy resin according to the present invention includes steps S1 to S10, which will be described later. These steps include mixing cardanol and vanillin (step S1), adding an acidic catalyst to carry out a polycondensation reaction (step S2), adding an alkaline solution to terminate the polycondensation reaction (step S3), adding an acidic substance to control the pH to neutral (step S4), adding an extraction solvent to obtain a phenolic resin (step S5), mixing the phenolic resin, epichlorohydrin, and a surfactant (step S6), adding a first alkaline solution to carry out a dehydrogenation reaction (step S7), adding a second alkaline solution to carry out a ring-closing reaction (step S8), removing the remaining epichlorohydrin (step S9), and adding an extraction solvent to obtain a phenolic epoxy resin (step S10).

[0028] In step S1, cardanol and vanillin are added to a reaction tank, where vanillin is the limiting reagent, i.e., the number of moles of cardanol added exceeds the number of moles of vanillin added, ensuring that the synthesized phenolic resin has hydroxyl groups at both ends, which is advantageous for the subsequent substitution reaction.

[0029] In one preferred embodiment, in order to ensure the specificity of the reaction, nitrogen may be introduced into the reaction tank, and the polycondensation reaction of cardanol and vanillin may be carried out in a nitrogen atmosphere.

[0030] In step S2, in order to accelerate the polycondensation reaction between cardanol and vanillin, the reaction tank is heated to a temperature of 60°C to 90°C, and an acidic catalyst is further added to carry out the polycondensation reaction between cardanol and vanillin, thereby forming a phenolic resin.

[0031] It is noteworthy that, in the conventional polycondensation reaction between formaldehyde and phenol, a weak acid is used. On the other hand, the reactivity of cardanol with vanillin is relatively low. Therefore, in the present invention, a strong acidic catalyst is used to promote the polycondensation reaction. Specifically, the acidic catalyst has an acidity constant (pKa) of less than 3.1 in water at 25°C.

[0032] When the acidic catalyst has a low acidity coefficient pKa (e.g., hydrochloric acid, sulfuric acid, phosphoric acid), it can dissociate into a relatively large number of hydrogen ions, which results in intense heat generation during the polycondensation reaction, making it difficult to control the progress of the reaction, and leading to a wide distribution range of the weight-average molecular weight of the phenolic resin (i.e., a high dispersion index of the polymer).

[0033] When the acidity coefficient pKa of the acid catalyst is relatively high (e.g., citric acid, oxalic acid), it is relatively difficult for the acid catalyst to dissociate into hydrogen ions, resulting in weak reactivity of cardanol and vanillin, and a relatively low molecular weight of the phenolic resin.

[0034] Experiments have shown that the acidity constant pKa of the acid catalyst in water at 25° C. is preferably −2.9 to 1.5, more preferably −2.0 to −1.5. For example, the acid catalyst may be methanesulfonic acid or p-toluenesulfonic acid, with methanesulfonic acid being most preferred.

[0035] In order to control the reaction stability of the polycondensation reaction, in addition to the temperature and the type of acid catalyst, the amount of the acid catalyst added is also controlled in the present invention. The amount of the acid catalyst added is 0.25 to 1 part by weight, preferably 0.5 to 0.6 parts by weight, based on 100 parts by weight of the total weight of cardanol and vanillin.

[0036] In step S3, the vanillin content in the reaction tank is measured by liquid chromatography (LC), and when the weight percent concentration of vanillin in the reaction tank becomes less than 0.1%, an alkaline solution is added to terminate the polycondensation reaction. In one exemplary embodiment, the polycondensation reaction in step S2 proceeds for about 3.5 to 4.5 hours.

[0037] Specifically, the addition of an alkaline solution can neutralize the acid catalyst and terminate the polycondensation reaction. The alkaline solution may be a 40 wt% to 60 wt% aqueous solution of sodium hydroxide or a 40 wt% to 60 wt% aqueous solution of potassium hydroxide, but the present invention is not limited thereto.

[0038] In step S4, an acidic substance is added to control the pH to a neutral level (i.e., pH 6.5 to 7.5), thereby preventing decomposition of the produced phenolic resin. For example, the acidic substance may be oxalic acid. However, there is no limit to the amount of acidic substance added, as long as the pH in the reaction tank is controlled to a neutral level.

[0039] After the steps S1 to S4, the reaction tank contains a variety of organic and aqueous phase substances, and the phenolic resin can be purified by washing and extraction with water.

[0040] In step S5, the mixture is washed with an extraction solvent, and the reaction tank is separated into an organic phase and an aqueous phase, with the phenolic resin present in the organic phase. The aqueous phase is then removed by reflux dehydration at a temperature of 110°C to 130°C, and the extraction solvent is then removed under a pressure environment of 5 torr to 400 torr to obtain the phenolic resin.

[0041] According to experiments, the extraction solvent may be selected from the group consisting of ethyl acetate, toluene, and methyl isobutyl ketone, which can achieve a relatively good extraction effect on phenolic resin, and methyl isobutyl ketone is the most preferred.

[0042] When cardanol of different purity levels was tested, the higher the purity of the cardanol, the lighter the color of the phenolic resin produced. Specifically, cardanol with a product number of NX-2024 manufactured by Cardolite has a purity of 87% or higher, and the phenolic resin produced therefrom has a relatively dark color. Cardanol with a product number of NX-2026 manufactured by Cardolite has a purity of 96% or higher, and the phenolic resin produced therefrom has a relatively light color.

[0043] In step S6, the phenolic resin obtained in step S5, epichlorohydrin (ECH), and a surfactant are mixed together. The surfactant improves the compatibility of the phenolic resin and epichlorohydrin and promotes the reaction between the epichlorohydrin and the phenolic resin, resulting in the substitution of hydroxyl groups of the phenolic resin with epoxy groups.

[0044] Specifically, the surfactant may be an alcohol ether solvent, for example, the surfactant may be selected from the group consisting of ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether.

[0045] In one preferred embodiment, the amount of epichlorohydrin added is 400 to 800 parts by weight per 100 parts by weight of the phenolic resin. For example, the amount of epichlorohydrin added may be 450, 500, 550, 600, 650, 700, or 750 parts by weight. More preferably, the amount of epichlorohydrin added may be 600 to 700 parts by weight per 100 parts by weight of the phenolic resin.

[0046] In steps S7 and S8, the reaction tank is heated to 55-70°C, and a first alkaline solution is added to carry out a dehydrogenation reaction, and then a second alkaline solution is further added to carry out a ring-closing reaction, thereby obtaining a phenolic epoxy resin. In one preferred embodiment, the reaction temperature of the ring-closing reaction is higher than that of the dehydrogenation reaction, and the temperature difference between the reaction temperatures of the ring-closing reaction and the dehydrogenation reaction is 5-10°C.

[0047] FIG. 2 illustrates the reaction mechanism between the phenolic resin and epichlorohydrin in steps S7 and S8. In the example shown in FIG. 2, the first alkaline solution is a 50 wt% aqueous solution of sodium hydroxide. The addition of the first alkaline solution removes the hydrogen atoms of the hydroxyl groups in the phenolic resin. The presence of a surfactant favors the reaction between epichlorohydrin and the phenolic resin, and the hydroxyl groups originally in the phenolic resin are replaced with epoxy groups. The second alkaline solution is a 50 wt% aqueous solution of sodium hydroxide. The addition of the second alkaline solution promotes the dechlorination of epichlorohydrin and closes the loop, completing the substitution reaction.

[0048] The types of the first alkaline solution and the second alkaline solution are not limited to those described above, and the first alkaline solution and the second alkaline solution may be the same or different. For example, the first alkaline solution and the second alkaline solution may independently be a 50 wt% aqueous potassium hydroxide solution.

[0049] In one example, the amount of the first alkaline solution added is greater than the amount of the second alkaline solution added, for example, the amount of the first alkaline solution added is 2.5 to 4 times the amount of the second alkaline solution added.

[0050] In step S7, the reaction tank is heated to a temperature of 55°C to 65°C, and then a first alkaline solution is added dropwise to carry out a dehydrogenation reaction, thereby removing the hydrogen atoms of the hydroxyl groups in the phenolic resin. For example, the dropping rate of the first alkaline solution is 0.1 g / min to 0.4 g / min. To observe the degree of the dehydrogenation reaction, the phenolic resin is irradiated with ultraviolet light having a wavelength of 310 nm, and the hydroxyl group content in the phenolic resin is quantified based on the absorbance. When the hydroxyl group equivalent of the phenolic resin becomes lower than 3% of the hydroxyl group equivalent of the original phenolic resin, a second alkaline solution is added, and step S8 is carried out.

[0051] In one example, the first alkaline solution is added dropwise for 1.5 to 3.5 hours, and the dehydrogenation reaction in step S7 takes approximately 1.5 to 3.5 hours. After the first alkaline solution is added dropwise, stirring is continued for 30 minutes to ensure complete dehydrogenation of the hydroxyl groups in the phenolic resin. The temperature is then raised to 65°C, and dehydration is carried out for 30 minutes under a pressure of 5 torr to 400 torr. Water is produced during the dehydrogenation reaction, and the presence of water can lead to hydrolysis of the phenolic resin. Therefore, after the dehydrogenation reaction is complete, a dehydration treatment is first performed once, and then step S8 is continued.

[0052] In step S8, the reaction tank is heated to a temperature of 60°C to 70°C, and then a second alkaline solution is added dropwise to carry out a ring-closing reaction, thereby promoting epichlorohydrin dechlorination and closing the loop. For example, the dropwise addition rate of the second alkaline solution is 0.05 g / min to 0.15 g / min. In one example, the dropwise addition time of the second alkaline solution is 1 to 2.5 hours, so that the ring-closing reaction time in step S8 is approximately 1 to 2.5 hours. After the dropwise addition of the second alkaline solution is completed, the temperature is raised to 75°C within 30 minutes, and dehydration is carried out for 30 minutes.

[0053] In step S9, unreacted epichlorohydrin is removed at a temperature of 120°C to 130°C, thereby preventing epichlorohydrin from affecting the purity of the phenolic epoxy resin.

[0054] In step S10, the reaction tank is cooled to a temperature of 70°C to 80°C, and then an extraction solvent and a neutralization solution are added at normal pressure and washed with water, resulting in the formation of an organic phase and an aqueous phase in the reaction tank. The extraction solvent extracts the phenolic epoxy resin into the organic phase, and the neutralization solution forms a sodium chloride salt together with the chloride ions removed from the epichlorohydrin. Next, the aqueous phase is removed by reflux dehydration at a temperature of 110°C to 130°C, and then the extraction solvent is removed under a pressure environment of 5 torr to 400 torr to obtain the phenolic resin.

[0055] Experiments have shown that the extraction solvent may be selected from the group consisting of ethyl acetate, toluene, and methyl isobutyl ketone, with methyl isobutyl ketone being preferred. The neutralization solution may be a 35 wt% aqueous sodium hydroxide solution, although the present invention is not limited thereto.

[0056] [Synthesis of phenolic epoxy resin] To prove that the manufacturing method of the present invention can manufacture phenolic epoxy resins, phenolic resins of Examples 1 to 3 were manufactured according to the above steps S1 to S5. After manufacturing, the weight average molecular weight of the phenolic resins was measured by gel permeation chromatography (GPC), and the hydroxyl equivalent weight of the phenolic resins was measured by a potentiometric titrator. The results are shown in Table 1.

[0057] According to the above steps S6 to S10, the phenolic resin of Example 1, epichlorohydrin, and a surfactant were mixed to produce the phenolic epoxy resins of Examples 4 to 6. After production, the epoxy equivalent of the phenolic epoxy resin was measured using a potentiometric titrator, and the viscosity of the phenolic epoxy resin was measured using a viscometer at a temperature of 25°C. The results are shown in Table 2.

[0058] [Example 1] 190 g (equivalent weight: 0.63 mol) of cardanol and 76 g (equivalent weight: 0.5 mol) of vanillin were added to a reaction tank, and nitrogen gas was introduced to maintain a nitrogen atmosphere. The reaction tank was heated, and when the temperature reached 70°C, 1.5 g of methanesulfonic acid (acid catalyst) was added, and the polycondensation reaction was carried out for 4 hours.

[0059] After the reaction was completed, 1 g of 50 wt% aqueous sodium hydroxide solution (alkaline solution) and 0.1 g of oxalic acid (acidic substance) were added to stop the polycondensation reaction, and the mixture was extracted with methyl isobutyl ketone (extraction solvent) and washed with water. After washing with water, the reaction tank was heated to 120°C and dehydrated under reflux, and then the extraction solvent was removed at a pressure of 10 torr to obtain a phenolic resin.

[0060] The phenolic resin in Example 1 was a pale yellow liquid, and the weight average molecular weight of the phenolic resin was 7406 g / mol, and the hydroxyl group equivalent of the phenolic resin was 230 g / equivalent.

[0061] [Example 2] The operating conditions of Example 2 were similar to those of Example 1, except that the polycondensation reaction was carried out at a temperature of 65°C in Example 2. The phenolic resin of Example 2 was a pale yellow liquid, and the weight-average molecular weight of the phenolic resin was 5329 g / mol, and the hydroxyl equivalent of the phenolic resin was 242 g / equivalent.

[0062] [Example 3] The operating conditions of Example 3 were similar to those of Example 1, except that the polycondensation reaction in Example 3 was carried out at a temperature of 85°C. The phenolic resin in Example 3 was a pale yellow liquid, and the weight-average molecular weight of the phenolic resin was 9593 g / mol, and the hydroxyl equivalent weight of the phenolic resin was 223 g / equivalent.

[0063] [Table 1]

[0064] According to the results in Table 1, biomass phenolic resin can be produced using cardanol and vanillin as raw materials according to steps S1 to S5 of the present invention. Furthermore, the weight-average molecular weight of the phenolic resin increases as the temperature of the polycondensation reaction increases.

[0065] The weight average molecular weight of the phenolic resin may be 4000 g / mol to 10000 g / mol when the temperature of the polycondensation reaction is 60° C. to 90° C. In another embodiment, the temperature of the polycondensation reaction may be a positive integer between 60° C. and 90° C., and the weight average molecular weight of the phenolic resin may be a positive integer between 4000 g / mol and 10000 g / mol.

[0066] The hydroxyl equivalent of the phenolic resin may be 200 g / equivalent to 250 g / equivalent, for example, 210 g / equivalent, 220 g / equivalent, 230 g / equivalent, or 240 g / equivalent.

[0067] [Example 4] To a reaction tank was added 150 g of the phenolic resin obtained in Example 1, 990 g of epichlorohydrin, and 125 g of diethylene glycol monomethyl ether (surfactant).

[0068] After heating the reaction tank to 60°C, 99 g of 50 wt% aqueous sodium hydroxide solution (first alkaline solution) was added dropwise to carry out the dehydrogenation reaction. The total addition time was 2.5 hours. After the addition was completed, stirring was carried out for 30 minutes to ensure complete dehydrogenation of the phenolic resin. After heating the reaction tank to 65°C, dehydration was carried out for 30 minutes at a pressure of 190 torr.

[0069] Next, 33 g of a 50 wt % aqueous sodium hydroxide solution (second alkaline solution) was added dropwise to carry out a ring-closing reaction, and the total dropwise addition time was 2 hours. After the dropwise addition was completed, the temperature was raised to 75°C within 30 minutes to dehydrate for 30 minutes, and then further raised to 125°C to remove residual epichlorohydrin.

[0070] When the reaction tank was cooled to 75°C, 200g of ethyl acetate (extraction solvent) and 15g of 35wt% aqueous sodium hydroxide solution (neutralization solution) were added and washed with water. After washing with water, the reaction tank was heated to 120°C and dehydrated under reflux, and the extraction solvent was removed at a pressure of 10 torr to obtain a phenolic epoxy resin. The epoxy equivalent of the phenolic epoxy resin in Example 4 was 312g / equivalent and its viscosity was 11,000cps.

[0071] [Example 5] The operating conditions of Example 5 were similar to those of Example 4, except that the amount of epichlorohydrin added in Example 5 was 1100 g and the dropwise addition time of the first alkaline solution was 1.5 hours. The epoxy equivalent of the phenolic epoxy resin in Example 5 was 308 g / equivalent, and its viscosity was 11,300 cps.

[0072] [Example 6] The operating conditions of Example 6 were similar to those of Example 4, with the difference being that the total dropping time of the first alkaline solution in Example 6 was 2 hours, the total dropping time of the second alkaline solution was 1.5 hours, and the extraction solvent used for water washing of the phenolic epoxy resin was methyl isobutyl ketone. The epoxy equivalent of the phenolic epoxy resin in Example 6 was 293 g / eq, and its viscosity was 12,100 cps.

[0073] [Table 2]

[0074] According to the results in Table 2, based on steps S6 to S10 of the present invention, the terminal groups of biomass phenolic resin may be substituted with epoxy groups, and a biomass material that combines the excellent properties of both epoxy resin and phenolic resin can be produced.

[0075] Based on Examples 4 to 6, the epoxy equivalent of the phenolic epoxy resin may be 250 g / eq to 350 g / eq, and the viscosity of the phenolic epoxy resin may be 10,000 cps to 15,000 cps. In other embodiments, the epoxy equivalent of the phenolic epoxy resin may be 250 g / eq to 350 g / eq, and the viscosity of the phenolic epoxy resin may be 10,000 cps to 15,000 cps.

[0076] [Advantageous Effects of the Embodiments] As an advantageous effect of the present invention, the phenolic epoxy resin and the production method thereof according to the present invention can produce a phenolic epoxy resin made from biomass materials, which can be used as an alternative to conventional petrochemical-derived phenolic epoxy resins, by virtue of the technical features of "adding cardanol and vanillin to a reaction tank" and "the acidity coefficient pKa of the acidic catalyst in water at 25°C is less than 3.1."

[0077] The above disclosure is merely a preferred embodiment of the present invention, and the scope of the claims of the present invention is not limited thereto. Therefore, all equivalent technical modifications made using the contents of the specification and drawings of the present invention are included in the scope of the claims of the present invention.

Claims

1. adding cardanol and vanillin, a limiting reagent, to a reaction tank; heating the reaction tank and adding an acid catalyst when the temperature reaches 60°C to 90°C to carry out a polycondensation reaction of the cardanol and the vanillin to form a phenolic resin; mixing the phenolic resin with epichlorohydrin at a temperature of 55°C to 70°C to carry out a substitution reaction to form a phenolic epoxy resin; The method for producing a phenolic epoxy resin, wherein the acidic catalyst has an acidity coefficient pKa in water at 25°C of less than 3.

1.

2. 2. The method for producing a phenolic epoxy resin according to claim 1, wherein the acidic catalyst has an acidity coefficient pKa in water at 25°C of -2 to 1.

5.

3. 2. The method for producing a phenolic epoxy resin according to claim 1, wherein the amount of the acidic catalyst added is 0.25 parts by weight to 1 part by weight, where the total weight of the cardanol and the vanillin is 100 parts by weight.

4. 2. The method for producing a phenolic epoxy resin according to claim 1, wherein the acidic catalyst is methanesulfonic acid.

5. 10. The method for producing a phenolic epoxy resin according to claim 1, further comprising quenching the polycondensation reaction by adding an alkaline solution to the reaction tank after forming the phenolic resin.

6. 6. The method for producing a phenolic epoxy resin according to claim 5, wherein the alkaline solution is an aqueous sodium hydroxide solution.

7. 6. The method for producing a phenolic epoxy resin according to claim 5, wherein after adding the alkaline solution, an acidic substance is added so as to control the pH of the phenolic resin to 6.5 to 7.

5.

8. The method for producing a phenolic epoxy resin according to claim 7, wherein the acidic substance is oxalic acid.

9. 8. The method for producing a phenolic epoxy resin according to claim 7, wherein after adding the acidic substance, an extraction solvent is added to extract the phenolic resin, and the phenolic resin and the epichlorohydrin are mixed to carry out a substitution reaction, and the extraction solvent is selected from the group consisting of ethyl acetate, toluene and methyl isobutyl ketone.

10. 2. The method for producing a phenolic epoxy resin according to claim 1, wherein the substitution reaction is carried out by mixing the phenolic resin, the epichlorohydrin, and a surfactant which is an alcohol ether solvent.

11. The method for producing a phenolic epoxy resin according to claim 1, wherein the weight average molecular weight of the phenolic resin is 4,000 g / mol to 10,000 g / mol.

12. 2. The method for producing a phenolic epoxy resin according to claim 1, wherein the hydroxyl group equivalent of the phenolic resin is 200 g / equivalent to 250 g / equivalent.

13. A phenolic epoxy resin produced by the method for producing a phenolic epoxy resin according to any one of claims 1 to 12.

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