Preparation method and application of naphthalene-based phenolic epoxy resin

Abstract

The application discloses a preparation method and application of a naphthalene phenolic epoxy resin, and the preparation method comprises the following steps: performing etherification reaction on a phenol containing a naphthalene ring structure, epichlorohydrin, a cosolvent I and an etherification catalyst, and performing post-treatment to obtain a naphthalene chlorohydrin ether; adding a cosolvent II, an aldehyde compound and a phenolic aldehyde condensation catalyst to perform polycondensation reaction, separating waste water, and obtaining a naphthalene phenolic chlorohydrin ether organic phase solution; adding the cosolvent II and dropwise adding a ring closure catalyst to perform ring closure reaction, and obtaining a naphthalene phenolic epoxy resin crude product; and dissolving the naphthalene phenolic epoxy resin crude product in a cosolvent III, adding a refining catalyst and a phase transfer catalyst to perform refining reaction, and obtaining a naphthalene phenolic epoxy resin finished product. The naphthalene phenolic epoxy resin has a low epoxy equivalent weight, the heat resistance of a cured product is excellent, and the content of hydrolysis chlorine in the resin is low, so that the corrosion risk of a subsequent prepared circuit can be reduced.

Description

Technical Field

[0001] This invention belongs to the field of special epoxy resin technology, specifically relating to a method for preparing a naphthalene-based phenolic epoxy resin and its application. Background Technology

[0002] Since the mid-20th century, epoxy resins, as an important class of thermosetting polymers, have been widely used in coatings, composite materials, electronic packaging, and other fields. In recent years, naphthol-based epoxy resins, developed by introducing naphthalene ring structures (often using naphthol as a raw material) into the epoxy resin backbone, have attracted widespread attention due to their unique properties. Naphthalene rings possess a rigid planar fused ring structure, high chemical stability, and hydrophobicity. The rigid structure of the naphthalene ring effectively restricts the movement of molecular chain segments, significantly increasing the glass transition temperature and thermal decomposition temperature of the resin, allowing it to maintain structural and performance stability even at high temperatures. Simultaneously, the introduction of naphthalene rings enhances the rigidity of the molecular chain and increases the crosslinking density, significantly reducing the material's coefficient of thermal expansion. This characteristic makes it more compatible with the thermal expansion behavior of electronic components such as silicon chips and ceramic substrates, greatly reducing interface failure problems caused by thermal stress and improving the long-term reliability of electronic devices. Furthermore, highly polar epoxy groups are generally detrimental to dielectric properties. The hydrophobicity of the naphthalene ring and its large π-conjugated system effectively reduce the dielectric constant and dielectric loss of the resin, enabling it to maintain excellent dielectric stability in high-frequency applications such as 5G communication and millimeter-wave radar. Therefore, naphthol-based epoxy resins represent an important development direction for high-performance epoxy resins and have become one of the key candidate materials for next-generation advanced encapsulation materials and high-performance composite matrix materials.

[0003] However, it is difficult to achieve an excellent balance between heat resistance, dimensional stability and electrical properties, and there is an urgent need to develop a naphthol-based epoxy resin material that has both excellent heat resistance and electrical properties. Summary of the Invention

[0004] To address the shortcomings of existing technologies, a method for preparing naphthalene-based phenolic epoxy resin is provided.

[0005] The objective of this invention is achieved through the following technical solution: In a first aspect, the present invention provides a method for preparing a naphthalene-based phenolic epoxy resin, the preparation method comprising, A phenol containing a naphthalene ring structure, epichlorohydrin, cosolvent I, and etherification catalyst were subjected to an etherification reaction, and the post-treatment yielded naphthalene-based glycidyl ethers. A condensation reaction was carried out by adding cosolvent II, aldehyde compounds, and a phenolic condensation catalyst to obtain a naphthalene-based phenolic glycidyl ether organic phase solution. Add cosolvent II and dropwise add ring-closing catalyst to carry out ring-closing reaction to obtain crude naphthalene-based phenolic epoxy resin; The crude naphthalene-based phenolic epoxy resin was dissolved in cosolvent III, and a refining catalyst and a phase transfer catalyst were added to carry out a refining reaction to obtain the naphthalene-based phenolic epoxy resin. The molar ratio of the phenol containing the naphthalene ring structure to epichlorohydrin is 1:4~8; The molar ratio of the naphthalene-based glycidyl ether and the aldehyde compound is 1:0.7~0.9; The phenol containing the naphthalene ring structure is selected from 2-naphthol, 2,7-dinaphthol, 1,6-dinaphthol, 1-naphthol or halonaphthol; The aldehyde compounds are selected from formaldehyde, paraformaldehyde, acetaldehyde, or butyraldehyde.

[0006] Based on this scheme, etherification is performed first to convert naphthol into glycidyl ether, followed by phenolic condensation. This allows each naphthalene ring unit to have an open-ring epoxy group before chain extension, resulting in higher epoxy functionality and a more uniform cross-linked network. Furthermore, the molecular weight can be controlled by the degree of condensation. If phenolic condensation is performed before etherification, the etherification reaction will be incomplete and the yield will be low. During purification, explosive polymerization will occur, producing a large amount of intermediate layers. Increasing the reaction temperature for etherification and ring closure at this point will lead to increased byproducts, epoxy equivalent, total chlorine, and hydrolyzed chlorine.

[0007] On the other hand, the inorganic phase OH is purified by using a phase transfer catalyst. - Introducing the organic phase allows for secondary ring closure of residual chlorine, forming epoxy groups, while effectively reducing the amount of hydrolyzable chlorine. Without purification, the total chlorine content and hydrolyzable chlorine in the product will increase significantly. Only through purification and phase transfer catalytic reaction can the hydrolyzable chlorine be controlled below 100 ppm, resulting in a low-chlorine, high-purity epoxy resin.

[0008] Based on this scheme, at this ratio, excess epichlorohydrin can inhibit the linear molecular growth after ring opening and reduce the formation of non-hydrolyzable chlorine. However, further increasing the amount of epichlorohydrin results in both raw material waste and the inability to further reduce the epoxy equivalent of the product, while increasing the total chlorine content.

[0009] Under this ratio, the aldehyde compounds control the degree of polymerization of the naphthalene-based epoxy resin molecular chain within the range of 1 to 10, resulting in a lower molecular weight of individual molecular chains. The increase in the number of epoxy groups is greater than the increase in molecular weight, thereby controlling the epoxy equivalent of the naphthalene-based epoxy resin within the range of 160 g / mol to 220 g / mol.

[0010] Based on this scheme, in the above-mentioned phenolic condensation reaction, aldehyde compounds, on the one hand, act as chain extenders to connect naphthalene rings through methylene bridges (-CH2-); secondly, they construct a rigid phenolic skeleton to improve the heat resistance of the material; thirdly, they control the hydroxyl density by controlling the degree of condensation, thereby regulating the epoxy equivalent; and fourthly, they adjust the amount of aldehyde to make the crosslinking density controllable and achieve designable performance.

[0011] In some specific embodiments of the present invention, the post-processing includes, After the etherification reaction is completed, the temperature is raised to 120~140℃, and the excess epichlorohydrin is recovered under a relative vacuum of 0.8~0.9.

[0012] Based on this scheme, the above method can recover the excess epichlorohydrin after the reaction, which helps to continue the condensation reaction and ring-closing reaction to obtain high-purity, low-chlorine naphthalene-based phenolic epoxy resin.

[0013] In some specific embodiments of the present invention, the naphthalene-based phenolic epoxy resin has an epoxy equivalent of 160~220 g / mol, total chlorine <1000 ppm, and hydrolyzed chlorine <100 ppm.

[0014] Based on this scheme, when the epoxy equivalent is controlled within the range of 160 g / mol to 220 g / mol, the pure resin and phenolic system, after curing, exhibits a high Tg. g This method effectively controls the glassy thermal expansion coefficient (CTE1) within the range of 70~120 ppm / ℃ and the elastic thermal expansion coefficient (CTE2) within the range of 150~200 ppm / ℃, exhibiting excellent heat resistance and maintaining a balance in overall performance. Simultaneously, controlling the total chlorine content to <1000 ppm and the hydrolyzed chlorine content to <100 ppm helps to effectively reduce the risk of corrosion to circuits caused by chlorine components in the resin during the preparation of electronic materials, thereby improving the safety and stability of the material during use.

[0015] In some specific embodiments of the present invention, the etherification catalyst is selected from one of quaternary ammonium salts and quaternary phosphorus salts; the quaternary ammonium salt is selected from one of tetramethylammonium chloride, tetraethylammonium chloride, benzyltriethylammonium chloride, tetramethylammonium bromide, and tetraethylammonium bromide; and the quaternary phosphorus salt is selected from one of triphenylethylphosphine bromide, tetraphenylphosphine bromide, and tetrabutylphosphine bromide.

[0016] In some specific embodiments of the present invention, the phenolic condensation catalyst is selected from one of acetic acid, sulfuric acid, nitric acid, and p-methanesulfonic acid.

[0017] Based on this scheme, using quaternary ammonium or quaternary phosphate salts as catalysts in the etherification reaction can generate only naphthalene-based chlorohydrin ether intermediates without further ring closure. Choosing an acidic condensation catalyst in this case does not affect the chlorohydrin ether structure and significantly increases the solubility of the naphthalene-based chlorohydrin ether, thereby reducing the difficulty of condensation and simplifying the process. Furthermore, using quaternary ammonium salts as etherification catalysts promotes the reaction in a homogeneous environment, reducing byproducts.

[0018] In some specific embodiments of the present invention, the closed-ring catalyst is selected from potassium hydroxide and sodium hydroxide. The above-mentioned closed-ring catalyst provides OH... - Ions promote intramolecular nucleophilic substitution in chlorohydrin ether intermediates, forming epoxy groups, which can achieve efficient ring closure, completely transform the chlorohydrin ether structure, and reduce the content of hydrolyzable chlorine. In the purification step, it works synergistically with quaternary ammonium salts to achieve efficient secondary ring closure.

[0019] In some specific embodiments of the present invention, the phase transfer catalyst includes, but is not limited to, benzyltriethylammonium chloride, tetramethylammonium chloride, tetraethylammonium bromide, and tetrabutylammonium bromide. The above-mentioned phase transfer catalysts can synergistically perform secondary ring-closure and dechlorination treatment on the crude product with the ring-closing catalyst. Simultaneously, the secondary ring-closure can be carried out under mild conditions, thereby effectively protecting the already formed epoxy groups.

[0020] In some specific embodiments of the present invention, co-solvent I is selected from one or more of toluene, ethylene glycol diethyl ether, ethylene glycol monoethyl ether, methyl isobutyl ketone, ethanol, and isopropanol; co-solvent II is selected from one or more of toluene, ethylene glycol monomethyl ether, methyl isobutyl ketone, and isopropanol; and co-solvent III is selected from toluene and methyl isobutyl ketone. All of the above co-solvents can dissolve the reaction raw materials, promote the contact between the two phases, and improve the efficiency of each reaction.

[0021] In some specific embodiments of the present invention, the etherification reaction is carried out at a temperature of 80~110°C and for a reaction time of 4~6 hours.

[0022] Based on this scheme, under the temperature conditions of the etherification reaction, naphthol is completely converted into a chlorohydrin ether structure with a narrow molecular weight distribution, and the resulting intermediate has a regular structure, which is beneficial for subsequent polycondensation reactions.

[0023] In some specific embodiments of the present invention, the temperature of the polycondensation reaction is 80~90°C, and the time of the polycondensation reaction is 6~10 h.

[0024] Based on this scheme, under the given temperature and duration conditions of the polycondensation reaction, the conversion rate of naphthol is fast and close to complete. Below 80°C or for less than 6 hours, unreacted naphthol chlorohydrin ethers remain in the system. Above 90°C and for more than 10 hours, the reaction is easily intensified, the molecular weight will increase disorderly, resulting in more insoluble products, which is not conducive to subsequent water washing and separation, thus reducing the yield.

[0025] In some specific embodiments of the present invention, the temperature of the closed-loop reaction is 100~120℃, and the time of the closed-loop reaction is 6~8 h.

[0026] Based on this technical solution, under the above-mentioned reaction temperature and duration conditions, hydrolysis and ring-opening to generate diols or polymerization reactions are avoided under alkaline conditions, thereby reducing the epoxy group content, increasing the epoxy equivalent, and abnormally increasing the viscosity.

[0027] In some specific embodiments of the present invention, the temperature of the purification reaction is 50~60℃, and the purification reaction time is 1~2h.

[0028] Based on this technical solution, under conditions of 50-60℃ and 1-2 hours, the phase transfer efficiency is high, the epoxy groups are stable, side reactions are few, and hydrolytic chlorine is low. At a purification temperature of 40℃, the purification reaction efficiency is low, while at 70℃, the epoxy equivalent increases and explosive polymerization is easily initiated. Extending the purification reaction time reduces the overall yield and generates more byproducts.

[0029] Secondly, the present invention also provides the application of the naphthalene-based phenolic epoxy resin prepared by the preparation method described in the first aspect in the preparation of electronic materials.

[0030] Based on this technical solution, the total chlorine content of the naphthalene-based phenolic epoxy resin is <1000 ppm and the hydrolyzed chlorine content is <100 ppm. In the preparation of electronic materials, this significantly reduces the risk of corrosion to circuits caused by chlorine components in the resin, and improves the safety and stability of electronic materials during use. Attached Figure Description

[0031] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the synthesis path in Embodiments 1-6 of the present invention.

[0033] Figure 2 The image shows the FT-IR spectrum of the product obtained in Example 1 of this invention.

[0034] Figure 3The image shows the FT-IR spectrum of the product obtained in Example 2 of this invention. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to specific embodiments. The following embodiments are not intended to limit the present invention, but only to illustrate the present invention. Unless otherwise specified, the experimental methods used in the following embodiments are generally performed under conventional conditions. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.

[0036] In this invention, the epoxy equivalent of the naphthol phenolic epoxy resin is determined according to GB / T4612-2008, "Determination of Epoxy Equivalent of Epoxy Compounds in Plastics". The specific test method is as follows: Take a sample containing 0.6 mmol to 0.9 mmol of epoxy groups, where the sample mass is in the range of (0.6 × EE ~ 0.9 × EE) mg, and EE is the estimated epoxy equivalent of the sample. Add 10 mL of chloroform, stir and heat to dissolve the sample, cool to room temperature, add 20 mL of glacial acetic acid and 10 mL of tetraethylammonium bromide solution, and use potentiometric titration. Place the electrode in the sample and titrate the solution with perchloric acid solution. Record the temperature t of the perchloric acid solution to correct for the volume of the solution when the temperature changes. Simultaneously, a blank test is performed, which is conducted using the same steps and reagents, but without a sample.

[0037] The total chlorine content of the naphthol phenolic epoxy resin in this invention is determined according to GB / T 4618.3-2008 Determination of Chlorine Content in Plastic Epoxy Resins Part 3: Total Chlorine. The specific test method is as follows: When weighing the sample, if the expected total chlorine content is less than 1%, weigh a sample containing 0.5~1.5 mg of chlorine; if the expected total chlorine content is greater than 1%, weigh a sample containing 5~15 mg of chlorine. Then, add 25 mL of diethylene glycol butyl ether and stir to dissolve the test sample. Subsequently, add 25 mL of a 1,2-propanediol solution of potassium hydroxide. While stirring, heat the solution under reflux for 10 min. After cooling, pour 5 mL of acetone into a reflux condenser and transfer the solution from the flask to a 200 mL beaker. The inside of the flask was washed three times with a total of 50 mL of glacial acetic acid, and the washing solution was added to the solution in the beaker. The electrode was placed in the solution. If the expected total chlorine content was less than 1%, potentiometric titration was performed with 0.01 mol / L silver nitrate solution. If the expected total chlorine content was greater than 1%, potentiometric titration was performed with 0.1 mol / L silver nitrate solution. Blank tests were performed using the same method.

[0038] The hydrolytic chlorine content of the naphthol phenolic epoxy resin in this invention is determined according to GB / T 4618.2-2008 Determination of chlorine content in epoxy resins for plastics - Part 2: Saponifiable chlorine. The specific test method is as follows: Weigh a sample containing 1.78 mg or less of saponifiable chlorine, add 25 mL of 2-butoxyethanol, stir and heat to dissolve the sample, cool to room temperature, take 25 mL of sodium hydroxide in 2-butoxyethanol solution and mix thoroughly. Let the mixture stand at room temperature for 2 h, add 100 mL of butanone and 25 mL of glacial acetic acid to the mixture and stir until the precipitate is completely dissolved. Place the electrode in the sample solution and perform potentiometric titration with silver nitrate standard solution.

[0039] Figure 1 Schematic diagrams of the synthetic pathways for Examples 1-6 are shown. Here, n is an average of 1-10. R1 is selected from hydrogen atoms or hydroxyl groups. When R1 is a hydrogen atom, R2, R3, and R4 are all hydrogen atoms; when R1 is a hydroxyl group, R2 and R3 are chlorohydrin ether groups, and R4 is a glycidyl group.

[0040] Example 1

[0041] This embodiment provides a method for preparing 2,7-dinaphthol phenolic epoxy resin, specifically as follows: (1) Etherification reaction: Add 160 g of 2,7-dinaphthol, 740 g of epichlorohydrin, 360 g of methyl isobutyl ketone and 0.8 g of tetramethylammonium chloride to a 2 L glass reactor equipped with a stirrer, thermometer and reflux condenser. Replace with nitrogen 3 to 5 times, heat the reaction mixture to 90 °C to carry out the etherification reaction, and keep warm for 4 h. After the reaction was completed, the temperature was raised to 120°C, and the excess epichlorohydrin was recovered under a relative vacuum of 0.8~0.9 to obtain naphthalene-based glycidyl alcohol ethers.

[0042] (2) Phenolic condensation reaction: 360 g of methyl isobutyl ketone was added to completely dissolve the naphthalene-based glycidyl ether product obtained in step (1), followed by the addition of 60 g of 40% formaldehyde aqueous solution, nitrogen purging 3-5 times, and heating to 80℃. 3 g of concentrated sulfuric acid was added to the reactor in two batches. The first batch consisted of 1 g of concentrated sulfuric acid, and the temperature was maintained at 80℃ for 2 h. The second batch consisted of 2 g of concentrated sulfuric acid, and the temperature was maintained at 80℃ for 4 h. 10 wt% sodium carbonate aqueous solution was added to neutralize the concentrated sulfuric acid. The mixture was washed until the pH of the aqueous phase was 7-8 to obtain the intermediate product, namely the methyl isobutyl ketone solution of 2,7-dinaphthol phenolic chlorohydrin ether.

[0043] (3) Ring-closing reaction: 360 g of methyl isobutyl ketone was added to the intermediate product obtained in step (2), the temperature was raised to 110°C, and then 140 g of 50% sodium hydroxide aqueous solution was slowly added dropwise to carry out the ring-closing reaction. The dropwise addition time was controlled within 2 h. After keeping the temperature at 110°C for 6 h, 280 g of pure water was added and stirred for 30 min. The aqueous phase was washed until the pH value reached 7~8. The mixture was allowed to stand and separated. The solvent was removed by negative pressure. The relative vacuum degree was 0.8~0.9, the temperature was controlled at 120°C, and finally nitrogen was bubbled to remove the residual methyl isobutyl ketone to obtain crude 2,7-dinaphthol phenolic epoxy resin.

[0044] (4) Refining and purification: Dissolve the crude 2,7-dinaphthol phenolic epoxy resin obtained in step (3) with 820 g of methyl isobutyl ketone, heat to 50°C, add 4.1 g of benzyltriethylammonium chloride and 50 g of 30% sodium hydroxide aqueous solution, react at 50°C for 1.0 h, after the reaction is completed, add pure water to wash until the pH of the aqueous phase is 7~8, filter with diatomaceous earth to remove insoluble matter, transfer the filtrate to another reactor, remove the solvent by negative pressure, the relative vacuum degree is 0.8~0.9, and the temperature is controlled at 110°C to obtain high-purity, low-chlorine 2,7-dinaphthol phenolic epoxy resin.

[0045] The synthetic route of the 2,7-dinaphthol phenolic epoxy resin in Example 1 is as follows:

[0046] Example 2

[0047] This embodiment provides a method for preparing 2,7-dinaphthol phenolic epoxy resin, specifically as follows: (1) Etherification reaction: Add 160g of 2,7-dinaphthol, 740g of epichlorohydrin, 360g of isopropanol and 0.8g of tetramethylammonium chloride to a 2L glass reactor equipped with a stirrer, thermometer and reflux condenser. Replace with nitrogen 3 to 5 times, heat the reaction mixture to 80℃ for etherification reaction and keep warm for 6 h. After the reaction was completed, the temperature was raised to 120°C, and the excess epichlorohydrin was recovered under a relative vacuum of 0.8~0.9 to obtain naphthalene-based glycidyl alcohol ethers.

[0048] (2) Phenolic condensation reaction: 360 g of isopropanol was added to completely dissolve the naphthalene-based glycidyl ether product obtained in step (1), followed by 60 g of 40% formaldehyde aqueous solution, nitrogen purging 3-5 times, and heating to 80℃. 3 g of glacial acetic acid was added to the reactor in two batches. The first batch consisted of 1 g of glacial acetic acid, and the temperature was maintained at 80℃ for 2 h. The second batch consisted of 2 g of glacial acetic acid, and the temperature was maintained at 80℃ for 4 h. 10 wt% sodium carbonate aqueous solution was added to neutralize the glacial acetic acid, and the intermediate product, namely the isopropanol solution of 2,7-dinaphthol phenolic chlorohydrin ether, was obtained.

[0049] (3) Ring-closing reaction: 360 g of isopropanol was added to the organic solution of the intermediate product obtained in step (2), the temperature was raised to 90℃ and refluxed, and 140 g of 50% sodium hydroxide aqueous solution was added dropwise to carry out the ring-closing reaction. The dropwise addition time was controlled within 2 h. After keeping the temperature at 90℃ for 6 h, 280 g of pure water was added and stirred for 30 min. The mixture was allowed to stand and separated. The solvent was removed by negative pressure with a relative vacuum of 0.8~0.9 and a temperature controlled at 120℃. Finally, nitrogen was bubbled to remove residual toluene to obtain crude 2,7-dinaphthol phenolic epoxy resin.

[0050] (4) Refining and purification: Dissolve the crude 2,7-dinaphthol phenolic epoxy resin obtained in step (3) with 820 g toluene, heat to 50°C, add 4.1 g of benzyltriethylammonium chloride and 50 g of 30% sodium hydroxide aqueous solution, react at 50°C for 1.0 h, after the reaction is completed, add pure water to wash until the pH of the aqueous phase is 7~8, filter with diatomaceous earth to remove insoluble matter, transfer the filtrate to another reactor, remove the solvent by negative pressure, the relative vacuum degree is 0.8~0.9, and the temperature is controlled at 110°C to obtain high-purity low-chlorine 2,7-dinaphthol phenolic epoxy resin.

[0051] The synthesis route of the 2,7-dinaphthol phenolic epoxy resin in Example 2 is the same as that in Example 1.

[0052] The FT-IR spectra of the final product 2,7-dinaphthol phenolic epoxy resin from Examples 1 and 2 were tested, and the results are as follows: Figure 2 and Figure 3 As shown. Among them, Figure 2 The image shows the FT-IR spectrum of the product from Example 1. Figure 3 The image shows the FT-IR spectrum of the product from Example 2. Figure 2 and Figure 3 As can be seen from the examples, 2,7-dinaphthol phenolic epoxy resin was successfully prepared in Examples 5 and 6.

[0053] Example 3 This embodiment provides a method for preparing 2-naphthol phenolic epoxy resin, specifically as follows: (1) Etherification reaction: Add 144 g of 2-naphthol, 370 g of epichlorohydrin, 185 g of methyl isobutyl ketone and 0.8 g of benzyltriethylammonium chloride to a 2L glass reactor equipped with a stirrer, thermometer and reflux condenser. Replace with nitrogen 3 to 5 times, heat the reaction mixture to 90℃ for etherification reaction and keep warm for 6 h. After the reaction was completed, the temperature was raised to 120°C, and the excess epichlorohydrin was recovered under a relative vacuum of 0.8~0.9 to obtain naphthalene-based glycidyl alcohol ethers.

[0054] (2) Phenolic condensation reaction: 360 g of methyl isobutyl ketone was added to completely dissolve the naphthalene-based glycidyl ether product obtained in step (1), followed by 60 g of 40% formaldehyde aqueous solution, nitrogen purging 3-5 times, and heating to 80℃. 3 g of concentrated sulfuric acid was added to the reactor in two batches. The first batch consisted of 1 g of concentrated sulfuric acid, and the temperature was maintained at 80℃ for 2 h. The second batch consisted of 2 g of concentrated sulfuric acid, and the temperature was maintained at 80℃ for 4 h. After the reaction was completed, 10 wt% sodium carbonate aqueous solution was added to neutralize the concentrated sulfuric acid. The mixture was washed with water until the pH of the aqueous phase reached 7-8, and the intermediate product, namely the methyl isobutyl ketone solution of 2-naphthol phenolic condensate glycidyl ether, was obtained.

[0055] (3) Ring-closing reaction: 360 g of methyl isobutyl ketone was added to the intermediate product obtained in step (2), the temperature was raised to 110°C, and then 140 g of 50% sodium hydroxide aqueous solution was slowly added dropwise to carry out the ring-closing reaction. The dropwise addition time was controlled at 2 h. After keeping the temperature at 110°C for 6 h, 280 g of pure water was added and stirred for 30 min. The aqueous phase was washed until the pH value reached 7~8. The mixture was allowed to stand and separated. The solvent was removed by negative pressure with a relative vacuum of 0.8~0.9 and the temperature was controlled at 120°C. Finally, nitrogen was bubbled to remove the residual methyl isobutyl ketone, and crude 2-naphthol phenolic epoxy resin was obtained.

[0056] (4) Refining and purification: Dissolve the crude 2-naphthol phenolic epoxy resin obtained in step (3) with 820 g of methyl isobutyl ketone, heat to 50°C, add 4.1 g of benzyltriethylammonium chloride and 50 g of 30% sodium hydroxide aqueous solution, react at 50°C for 1.0 h, after the reaction is completed, add pure water to wash until the pH of the aqueous phase is 7~8, filter with diatomaceous earth to remove insoluble matter, transfer the filtrate to another reactor, remove the solvent by negative pressure, the relative vacuum degree is 0.8~0.9, and the temperature is controlled at 120°C to obtain high-purity low-chlorine 2-naphthol phenolic epoxy resin.

[0057] The synthesis route of the 2-naphthol phenolic epoxy resin in Example 3 is as follows:

[0058] Example 4

[0059] This embodiment provides a method for preparing 2-naphthol phenolic epoxy resin, specifically as follows: (1) Etherification reaction: Add 144 g of 2-naphthol, 370 g of epichlorohydrin, 185 g of isobutanol and 0.8 g of tetramethylammonium chloride to a 2L glass reactor equipped with a stirrer, thermometer and reflux condenser. Replace with nitrogen 3 to 5 times, heat the reaction mixture to 100℃ for etherification reaction and keep warm for 4 h. After the reaction was completed, the temperature was raised to 120°C, and the excess epichlorohydrin was recovered under a relative vacuum of 0.8~0.9 to obtain naphthalene-based glycidyl alcohol ethers.

[0060] (2) Phenolic condensation reaction: 360 g of toluene was added to completely dissolve the naphthalene-based glycidyl ether product obtained in step (1). Then, 60 g of 40% formaldehyde aqueous solution was added, and nitrogen was used to replace the solution 3-5 times. The temperature was raised to 90℃. 3 g of glacial acetic acid was added to the reactor in two batches. The first batch consisted of 1 g of glacial acetic acid, and the temperature was maintained at 90℃ for 2 h. The second batch consisted of 2 g of glacial acetic acid, and the temperature was maintained at 90℃ for 4 h. After the reaction was completed, 10 wt% sodium carbonate aqueous solution was added to neutralize the glacial acetic acid. The mixture was washed until the pH of the aqueous phase was 7-8 to obtain the intermediate product, namely a toluene solution of 2-naphthol phenolic chlorohydrin ether.

[0061] (3) Ring-closing reaction: 360 g of toluene was added to the intermediate product obtained in step (2), the temperature was raised to 110℃, and 140 g of 50% sodium hydroxide aqueous solution was added dropwise to carry out the ring-closing reaction. The dropwise addition time was controlled within 2 h. After keeping the temperature at 110℃ for 6 h, 280 g of pure water was added and stirred for 30 min. The aqueous phase was washed until the pH value reached 7~8. The mixture was allowed to stand and separated. The solvent was removed by negative pressure with a relative vacuum of 0.8~0.9 and the temperature was controlled at 120℃. Finally, nitrogen was bubbled to remove the residual toluene to obtain crude 2-naphthol phenolic epoxy resin.

[0062] (4) Refining and purification: Dissolve the crude 2-naphthol phenolic epoxy resin obtained in step (3) with 820 g toluene, heat to 60℃, add 4.1 g tetramethylammonium chloride and 50 g 20% ​​sodium hydroxide aqueous solution, react at 60℃ for 1.0 h, after the reaction is completed, add pure water to wash until the pH of the aqueous phase is 7~8, filter with diatomaceous earth to remove insoluble matter, transfer the filtrate to another reactor, remove the solvent by negative pressure, the relative vacuum degree is 0.8~0.9, the temperature is controlled at 110℃, and high-purity low-chlorine 2-naphthol phenolic epoxy resin is obtained.

[0063] The synthesis route of the 2-naphthol phenolic epoxy resin in Example 4 is the same as that in Example 3.

[0064] Example 5 This embodiment provides a method for preparing 1,6-dinaphthol phenolic epoxy resin, specifically as follows: (1) Etherification reaction: Add 160 g of 1,6-dinaphthol, 740 g of epichlorohydrin, 360 g of ethylene glycol diethyl ether, and 0.8 g of tetramethylammonium bromide to a 2 L glass reactor equipped with a stirrer, thermometer and reflux condenser. Replace with nitrogen 3 to 5 times, heat the reaction mixture to 90 °C for etherification reaction, and keep warm for 6 h. After the reaction was completed, the temperature was raised to 120°C, and the excess epichlorohydrin was recovered under a relative vacuum of 0.8~0.9 to obtain naphthalene-based glycidyl alcohol ethers.

[0065] (2) Phenolic condensation reaction: 360 g of ethylene glycol diethyl ether was added to completely dissolve the naphthalene-based glycidyl ether product obtained in step (1). Then, 60 g of 40% formaldehyde aqueous solution was added, and nitrogen was used to replace the solution 3-5 times. The temperature was raised to 90℃. 3 g of concentrated sulfuric acid was added to the reaction vessel in two batches. The first batch consisted of 1 g of concentrated sulfuric acid, and the temperature was maintained at 90℃ for 2 h. The second batch consisted of 2 g of concentrated sulfuric acid, and the temperature was maintained at 90℃ for 4 h. After the reaction was completed, 10 wt% sodium carbonate aqueous solution was added to neutralize the concentrated sulfuric acid. After separation, the intermediate product, namely the ethylene glycol diethyl ether solution of 1,6-dinaphthol phenolic chlorohydrin ether, was obtained.

[0066] (3) Ring-closing reaction: 360 g of ethylene glycol diethyl ether was added to the intermediate product obtained in step (2), the temperature was raised to 110°C, and then 140 g of 50% sodium hydroxide aqueous solution was slowly added dropwise to carry out the ring-closing reaction. The dropwise addition time was controlled within 2 h. After keeping the temperature at 110°C for 6 h, 280 g of pure water was added and stirred for 30 min. The mixture was allowed to stand and separated. The solvent was removed by negative pressure with a relative vacuum of 0.8~0.9 and a temperature controlled at 120°C. Finally, nitrogen was bubbled to remove the residual ethylene glycol diethyl ether to obtain crude 1,6-dinaphthol phenolic epoxy resin.

[0067] (4) Refining and purification: Dissolve the crude 1,6-dinaphthol phenolic epoxy resin obtained in step (3) with 820 g of methyl isobutyl ketone, heat to 50°C, add 4.1 g of benzyltriethylammonium chloride and 50 g of 30% sodium hydroxide aqueous solution, react at 50°C for 1.0 h, after the reaction is completed, add pure water to wash until the pH of the aqueous phase is 7~8, filter with diatomaceous earth to remove insoluble matter, transfer the filtrate to another reactor, remove the solvent by negative pressure, the relative vacuum degree is 0.8~0.9, and the temperature is controlled at 110°C to obtain high-purity low-chlorine 1,6-dinaphthol phenolic epoxy resin.

[0068] The synthesis route of the 1,6-dinaphthol phenolic epoxy resin in Example 5 is as follows:

[0069] Example 6 This embodiment provides a method for preparing 1,6-naphthyldiphenol phenolic epoxy resin, specifically as follows: (1) Etherification reaction: Add 160g of 1,6-dinaphthol, 740g of epichlorohydrin, 360g of ethylene glycol monoethyl ether, and 0.8g of tetraethylammonium chloride to a 2L glass reactor equipped with a stirrer, thermometer and reflux condenser. Replace with nitrogen 3 to 5 times, heat the reaction mixture to 100℃ for etherification reaction, and keep warm for 4 h. After the reaction was completed, the temperature was raised to 120°C, and the excess epichlorohydrin was recovered under a relative vacuum of 0.8~0.9 to obtain naphthalene-based glycidyl alcohol ethers.

[0070] (2) Phenolic condensation reaction: 360 g of ethylene glycol monoethyl ether was added to completely dissolve the naphthalene-based glycidyl ether obtained in step (1). Then, 60 g of 40% formaldehyde aqueous solution was added, and nitrogen was used to replace the solution 3-5 times. The temperature was raised to 80℃. 3 g of glacial acetic acid was added to the reactor in two batches. The first batch consisted of 1 g of glacial acetic acid, and the temperature was maintained at 80℃ for 2 h. The second batch consisted of 2 g of glacial acetic acid, and the temperature was maintained at 90℃ for 4 h. The glacial acetic acid was neutralized by adding 10 wt% sodium carbonate aqueous solution to obtain the intermediate product, namely, the ethylene glycol monoethyl ether solution of 1,6-naphthodiol phenolic chlorohydrin ether.

[0071] (3) Ring-closing reaction: 360 g of ethylene glycol monoethyl ether was added to the intermediate product obtained in step (2), the temperature was raised to 110°C, and 140 g of 50% sodium hydroxide aqueous solution was added dropwise to carry out the ring-closing reaction. The dropwise addition time was controlled within 2 h. After keeping the temperature at 110°C for 6 h, 280 g of pure water was added and stirred for 30 min. The mixture was allowed to stand and separated. The solvent was removed by negative pressure with a relative vacuum of 0.8~0.9 and a temperature controlled at 120°C. Finally, nitrogen was bubbled to remove the residual ethylene glycol monoethyl ether to obtain crude 1,6-dinaphthol phenolic epoxy resin.

[0072] (4) Refining and purification: Dissolve the crude 1,6-dinaphthol phenolic epoxy resin obtained in step (3) with 820 g toluene, heat to 50°C, add 4.1 g of benzyltriethylammonium chloride and 50 g of 20% sodium hydroxide aqueous solution, react at 50°C for 1.0 h, after the reaction is completed, add pure water to wash until the pH of the aqueous phase is 7~8, filter with diatomaceous earth to remove insoluble matter, transfer the filtrate to another reactor, remove the solvent by negative pressure, the relative vacuum degree is 0.8~0.9, and the temperature is controlled at 110°C to obtain high-purity low-chlorine 1,6-dinaphthol phenolic epoxy resin.

[0073] The synthesis route of the 1,6-naphthol phenolic epoxy resin in Example 6 is the same as that in Example 5.

[0074] The yields, epoxy equivalents, total chlorine, and hydrolyzed chlorine of Examples 1-6 were determined, and the results are shown in Table 1.

[0075] Table 1. Comparison of yield, epoxy equivalent, total chlorine, and hydrolyzed chlorine in Examples 1-6

[0076]

[0077] As shown in Table 1, the naphthalene-based phenolic epoxy resins prepared in Examples 1-6 of this invention all achieved yields of over 95%, with the highest yield reaching 98%. The epoxy equivalent was consistently below 220 g / mol, indicating high epoxy functionality. This resulted in more complete curing and crosslinking of the pure resin with the phenolic system, leading to higher Tg. gIt exhibits excellent heat resistance. Meanwhile, the total chlorine content is below 1000 ppm, and the hydrolyzed chlorine content is below 100 ppm, effectively reducing the risk of corrosion to subsequently manufactured circuits by chlorine in the resin. This enhances the safety and stability of the material during use, making it suitable for direct application in high-end electronic materials such as copper-clad laminates and electronic packaging.

[0078] In summary, this invention overcomes the problems of insufficient etherification, easy burst polymerization, and multiple intermediate layers in traditional processes by employing a unique synthetic route of first etherification, then polycondensation, and finally ring closure, thereby obtaining high-purity naphthalene-based phenolic epoxy resins with high yield. Using quaternary ammonium or quaternary phosphate salts as catalysts in the etherification reaction ensures that only naphthalene-based chlorohydrin ether intermediates are generated without further ring closure. Choosing an acidic condensation catalyst at this point does not affect the chlorohydrin ether structure and significantly increases the solubility of the naphthalene-based chlorohydrin ether, thus significantly reducing the difficulty of condensation and simplifying the process. Furthermore, adding excess epichlorohydrin suppresses side reactions and reduces the formation of non-hydrolyzable chlorine. The addition of purification and phase transfer catalytic steps achieves secondary ring closure and deep chlorination reduction.

[0079] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a naphthalene-based phenolic epoxy resin, characterized in that: include, A phenol containing a naphthalene ring structure, epichlorohydrin, cosolvent I, and etherification catalyst were subjected to an etherification reaction, and the post-treatment yielded naphthalene-based glycidyl ethers. A condensation reaction was carried out by adding cosolvent II, aldehyde compounds, and a phenolic condensation catalyst to obtain a naphthalene-based phenolic glycidyl ether organic phase solution. Add cosolvent II and dropwise add ring-closing catalyst to carry out ring-closing reaction to obtain crude naphthalene-based phenolic epoxy resin; The crude naphthalene-based phenolic epoxy resin was dissolved in cosolvent III, and a refining catalyst and a phase transfer catalyst were added to carry out a refining reaction to obtain the naphthalene-based phenolic epoxy resin. The molar ratio of the phenol containing the naphthalene ring structure to epichlorohydrin is 1:4~8; The molar ratio of the naphthalene-based glycidyl ether and the aldehyde compound is 1:0.7~0.9; The phenol containing the naphthalene ring structure is selected from 2-naphthol, 2,7-dinaphthol, 1-naphthol, 1,6-dinaphthol or halonaphthol; The aldehyde compounds are selected from formaldehyde, paraformaldehyde, acetaldehyde, or butyraldehyde.

2. The preparation method according to claim 1, characterized in that: The post-processing includes, After the etherification reaction is completed, the temperature is raised to 120~140℃, and the excess epichlorohydrin is recovered under a relative vacuum of 0.8~0.

9.

3. The preparation method according to claim 1, characterized in that: The naphthalene-based phenolic epoxy resin has an epoxy equivalent of 160~220 g / mol, total chlorine <1000 ppm, and hydrolyzed chlorine <100 ppm.

4. The preparation method according to claim 1, characterized in that: The etherification catalyst is selected from one of quaternary ammonium salts and quaternary phosphorus salts; the quaternary ammonium salt is selected from one of tetramethylammonium chloride, tetraethylammonium chloride, benzyltriethylammonium chloride, tetramethylammonium bromide, and tetraethylammonium bromide; the quaternary phosphorus salt is selected from one of triphenylethylphosphine bromide, tetraphenylphosphine bromide, and tetrabutylphosphine bromide.

5. The preparation method according to claim 1, characterized in that: The phenolic condensation catalyst is selected from acetic acid, sulfuric acid, nitric acid, and p-methanesulfonic acid; the ring-closing catalyst is selected from potassium hydroxide and sodium hydroxide; the phase transfer catalyst includes, but is not limited to, benzyltriethylammonium chloride, tetramethylammonium chloride, tetraethylammonium bromide, and tetrabutylammonium bromide.

6. The preparation method according to claim 1, characterized in that: The co-solvent I is selected from one or more of toluene, ethylene glycol diethyl ether, ethylene glycol monoethyl ether, methyl isobutyl ketone, ethanol, and isopropanol; the co-solvent II is selected from one or more of toluene, ethylene glycol monomethyl ether, methyl isobutyl ketone, and isopropanol; and the co-solvent III is selected from toluene and methyl isobutyl ketone.

7. The preparation method according to claim 4, characterized in that: The etherification reaction is carried out at a temperature of 80-110°C for 4-6 hours.

8. The preparation method according to claim 5, characterized in that: The polycondensation reaction is carried out at a temperature of 80-90°C for 6-10 hours.

9. The preparation method according to claim 5, characterized in that: The closed-loop reaction is carried out at a temperature of 100~120℃ for 6~8 hours.

10. The preparation method according to claim 5, characterized in that: The purification reaction is carried out at a temperature of 50-60°C for 1-2 hours.

11. The application of the naphthalene-based phenolic epoxy resin prepared by any one of the preparation methods according to claims 1 to 10 in the preparation of electronic materials.

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