A method for preparing an alicyclic epoxy resin

Abstract

The application discloses a preparation method of an alicyclic epoxy resin. The method comprises the following steps: performing two-stage etherification reactions of bisphenol A and epichlorohydrin under the action of a quaternary ammonium salt catalyst at low temperature and high temperature to obtain chlorohydrin ether; and sequentially performing catalytic hydrogenation reaction and ring closure reaction on the chlorohydrin ether. The method is simple and safe, the hydrogenation rate of benzene rings is high, and the prepared alicyclic epoxy resin has the characteristics of low epoxy equivalent weight and low total chlorine content.

Description

Technical Field

[0001] This invention relates to a method for preparing alicyclic epoxy resins, and more particularly to a method for preparing alicyclic 2,2′-bis(4-hydroxycyclohexyl)propane diglycidyl ether epoxy resin, belonging to the field of epoxy resin synthesis technology. Background Technology

[0002] Bisphenol A epoxy resins possess excellent adhesion, heat resistance, chemical resistance, and electrical properties, making them widely used in coatings, adhesives, fiberglass, laminates, electronic casting, potting, and encapsulation. However, due to the presence of benzene rings in their structure, their weather resistance, yellowing resistance, and UV resistance are relatively poor, limiting their application range, especially in outdoor applications. To improve the resin's weather resistance, yellowing resistance, and UV resistance, hydrogenated saturated double bonds are often used to enhance its antioxidant properties.

[0003] The properties of cured alicyclic 2,2′-di(4-hydroxycyclohexyl)propane diglycidyl ether epoxy resin are similar to those of bisphenol A type epoxy resin. However, due to the hydrogenation of the benzene ring to a saturated six-membered ring, its viscosity is significantly lower than that of ordinary bisphenol A type epoxy resin. The cured product has better thermal stability, chemical stability, corona resistance, and weather resistance. It is widely used in outdoor coatings, outdoor casting materials, and LED encapsulation materials, and can replace ordinary bisphenol A type epoxy resin in projects with requirements for weather resistance and UV resistance.

[0004] There are generally two methods for preparing 2,2′-bis(4-hydroxycyclohexyl)propane diglycidyl ether epoxy resin. One method involves etherifying hydrogenated bisphenol A with epichlorohydrin under a catalyst, followed by cyclization under alkali. Chinese patents CN102766113A and CN104193961A disclose a method using hydrogenated bisphenol A and epichlorohydrin as raw materials, with Lewis acid as a catalyst for etherification, followed by alkali-based ring-closing epoxidation to obtain hydrogenated bisphenol A epoxy resin. However, this method suffers from difficulties in etherifying alcohol hydroxyl groups compared to phenolic hydroxyl groups, requiring higher etherification temperatures and more β-addition during etherification, resulting in a high total chlorine content (typically 3-5%). This significantly impacts the product's performance and makes it unsuitable for electrical applications and applications requiring high weather resistance.

[0005] Another method involves the direct hydrogenation of bisphenol A epoxy resin. US Patent 6060611A discloses a method using bisphenol A epoxy resin as a raw material and tetrahydrofuran as a solvent to directly hydrogenate the resin at a temperature of 30–150°C and a pressure of 2–30 MPa to obtain hydrogenated bisphenol A epoxy resin. This method uses direct hydrogenation of the epoxy resin, causing partial hydrogenation and decomposition of the epoxy groups, with a decomposition rate of 5–10%. Using tetrahydrofuran as a solvent is problematic because tetrahydrofuran is easily oxidized; trace amounts of peroxides in tetrahydrofuran can reduce the activity of the hydrogenation catalyst, or even deactivate it, affecting the hydrogenation rate of the benzene ring in the product. Chinese Patent CN100513453A discloses a method using bisphenol A epoxy resin as a raw material and ethyl acetate as a solvent to directly hydrogenate the resin at a temperature of 30–150°C and a pressure of 2–15 MPa to obtain hydrogenated bisphenol A epoxy resin. This method uses direct hydrogenation of epoxy resin to decompose some of the epoxy groups, with a decomposition rate of 7-10%. Ethyl acetate is used as a solvent, and ethyl acetate is easily decomposed by hydrogenation under the action of a hydrogenation catalyst. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for preparing alicyclic epoxy resin, which has the characteristics of high hydrogenation rate of benzene ring, low epoxy equivalent and low total chlorine content.

[0007] To achieve the above-mentioned technical objectives, the present invention provides a method for preparing an alicyclic epoxy resin, wherein bisphenol A and epichlorohydrin are subjected to a two-stage etherification reaction at low temperature and high temperature under the action of a quaternary ammonium salt catalyst to obtain a chlorohydrin ether; the chlorohydrin ether is then subjected to a catalytic hydrogenation reaction and a ring-closing reaction in sequence to obtain the final product.

[0008] This invention first uses a quaternary ammonium salt as a catalyst, avoiding the use of catalysts containing sodium ions, to reduce the influence of sodium ions on the hydrogenation catalyst and lay the foundation for improving the hydrogenation rate of the benzene ring in chlorohydrin ethers. Then, by controlling the two-stage etherification reaction conditions, firstly, low-temperature etherification reduces etherification side reactions and increases the epoxy value of the product, followed by high-temperature etherification to ensure complete reaction of bisphenol A, and then catalytic hydrogenation reaction, which can hydrogenate the benzene ring on the chlorohydrin ether at a lower temperature, avoiding the decomposition of the chlorohydrin ether, increasing the benzene ring hydrogenation rate, and reducing the total chlorine content. Finally, by controlling the time of alkali addition, a ring-closing reaction is carried out. The final alicyclic epoxy resin has a high benzene ring hydrogenation rate, low epoxy equivalent, and low total chlorine content.

[0009] As a preferred embodiment, the first stage etherification reaction conditions of the two-stage etherification reaction are: temperature 60–80°C, time 3–4 hours; the second stage etherification reaction conditions are: temperature 95–105°C, time 0.5–1 hour. This invention employs a two-stage etherification method and controls the etherification conditions to ensure complete bisphenol A reaction. First, a relatively long low-temperature etherification process reduces etherification side reactions and increases the epoxy value of the product, while allowing most of the substrate to undergo etherification. Then, a short high-temperature etherification process is performed. This short high-temperature etherification ensures complete conversion of bisphenol A, while excessively long high-temperature etherification leads to side reactions. If the first-stage etherification temperature is too high or the etherification reaction time is too long, it will increase etherification side reactions and result in a low epoxy value in the product. If the second-stage etherification temperature is too low or the etherification time is too short, the bisphenol A etherification will be incomplete, resulting in a low epoxy value in the product. Furthermore, if the two-stage etherification reaction is not adopted, the content of hydrolyzed chlorine and the viscosity of the liquid in the product will increase significantly, while the hydrogenation rate of the benzene ring will decrease.

[0010] As a preferred embodiment, the quaternary ammonium salt catalyst is one of n-pentyltriphenylammonium bromide, tetrabutylammonium chloride, tetramethylammonium chloride, and benzyltriethylammonium chloride. The use of a quaternary ammonium salt as a catalyst in this invention avoids the introduction of sodium ions in the early stages, which is beneficial for subsequently improving the hydrogenation rate.

[0011] As a preferred embodiment, the molar ratio of bisphenol A to epichlorohydrin is 1:5 to 8. This invention controls the molar ratio of bisphenol A and epichlorohydrin to ensure complete reaction of bisphenol A and reduce byproducts generated in subsequent operations. If the molar ratio of bisphenol A to epichlorohydrin is too high, bisphenol A cannot react completely, resulting in bisphenol A residue and ultimately affecting the performance of the epoxy resin. If the molar ratio of bisphenol A to epichlorohydrin is too low, it increases the difficulty of subsequent impurity removal, leading to an increase in the chlorine content of the epoxy resin.

[0012] As a preferred embodiment, the mass ratio of bisphenol A to the quaternary ammonium salt catalyst is 100:1 to 2.

[0013] As a preferred embodiment, the conditions for the catalytic hydrogenation reaction are: temperature 60–120°C, pressure 4–8 MPa, and time 1.5–4 h. In this invention, if the catalytic hydrogenation reaction temperature is too low or the pressure is too low, the activation energy for the reaction will not be reached, and the reaction cannot proceed. Conversely, if the reaction temperature is too high or the pressure is too high, the reaction will be too rapid and release a large amount of heat. This will increase the epoxy group decomposition rate of the obtained bisphenol A epoxy resin and also pose a safety hazard.

[0014] As a preferred embodiment, the catalyst used in the catalytic hydrogenation reaction is an Rh / L molecular sieve catalyst.

[0015] As a preferred embodiment, the mass ratio of the catalyst to the chlorohydrin ether is 1 to 4:100.

[0016] As a preferred embodiment, an aqueous solution of sodium hydroxide and / or an aqueous solution of potassium hydroxide are used as a promoter in the ring-closing reaction, more preferably an aqueous solution of sodium hydroxide with a concentration of 20-30%. The role of sodium hydroxide in this invention is dechlorination; sodium hydroxide reacts with chlorine to produce sodium chloride, which then forms an epoxy group in the ring-closing reaction.

[0017] As a preferred embodiment, the molar ratio of the sodium hydroxide aqueous solution and / or potassium hydroxide aqueous solution to the hydrochlorohydrin ether is 2.1 to 2.5:1. If the molar ratio of the alkali solution to the hydrochlorohydrin ether is too low, incomplete ring closure of the product will occur; if the molar ratio is too high, cross-linking between product molecules will occur, affecting product quality.

[0018] As a preferred embodiment, the conditions for the ring-closure reaction are: a temperature of 90–100°C, an alkali addition time of 2–4 hours, and a ring-closure reaction time of 7–14 hours. Since the ring-closure reaction is endothermic, a certain temperature must be maintained during the reaction. However, if the temperature is too high, the ring-closed epoxy resin will undergo ring-opening polymerization at high temperatures, which will affect product quality.

[0019] As a preferred embodiment, the solvent used in the ring-closing reaction is at least one of toluene, ethylbenzene, xylene, methyl isobutyl ketone, and methyl ethyl ketone.

[0020] As a preferred embodiment, the mass ratio of solvent to hydrochlorohydrin ether used in the ring-closing reaction is 0.5 to 1:1. In this invention, if the mass ratio of solvent to hydrochlorohydrin ether is too high, the final epoxy resin will have a high organic chlorine content; if the mass ratio is too low, it will hinder the ring-closing reaction.

[0021] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0022] 1) In the preparation method of the present invention, the ring-opening etherification reaction uses a quaternary ammonium salt catalyst, which can effectively reduce the sodium ion content in chlorohydrin ethers and reduce the influence of sodium ions on the hydrogenation catalyst, thus laying the foundation for improving the hydrogenation rate of benzene ring in chlorohydrin ethers.

[0023] 2) In the preparation method of the present invention, the ring-opening etherification reaction is first etherified at low temperature to reduce etherification side reactions and increase the epoxy value of the product, and then etherified at high temperature to ensure complete conversion of bisphenol A.

[0024] 3) The Rh / L molecular sieve catalyst used in the hydrogenation reaction of the preparation method of the present invention can achieve a hydrogenation rate of more than 97% for the chlorohydrin ether benzene ring at a relatively low hydrogenation temperature.

[0025] 4) The alicyclic 2,2′-bis(4-hydroxycyclohexyl)propane diglycidyl ether epoxy resin prepared by the present invention has a benzene ring hydrogenation rate of over 97%, an epoxy equivalent of 185-192 g / eq, and a total chlorine content of no more than 0.3%. Detailed Implementation

[0026] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0027] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0028] Unless otherwise specified, all reagents and raw materials used in this invention are commercially available products or products that can be prepared by known methods.

[0029] The preparation method of the Rh / L molecular sieve catalyst used in this invention is as follows: 100g of L molecular sieve (Changling Branch of Sinopec Catalyst Company) is weighed and impregnated with an equal volume of RhCl3·3H2O (Rh≥39%) solution with a concentration of 12.9g / 100mL. The impregnation temperature is 30℃ and the impregnation time is 8h. The impregnation solution is dried at 120℃ for 24h, ground into fine powder, and reduced at 280℃ for 2h under a hydrogen atmosphere to obtain a molecular sieve catalyst with a mass percentage content of 5% Rh / L.

[0030] By changing the concentration of RhCl3·3H2O (Rh≥39%) solution to 8 g / 100 mL and 26 g / 100 mL respectively, and following the same method as above, 3% Rh / L molecular sieve catalysts and 10% Rh / L molecular sieve catalysts were prepared.

[0031] Example 1

[0032] 228.3 g of bisphenol A and 555 g of epichlorohydrin were added to a reaction vessel and stirred under nitrogen protection to completely dissolve bisphenol A in epichlorohydrin. The mixture was heated to 70 °C, and 2.3 g of n-pentyltriphenylammonium bromide was added. The reaction was carried out at 70 °C for 3 h, and then heated to 105 °C for 0.5 h. The mixture was washed with water until the pH of the aqueous phase was 6.5-7, and then excess epichlorohydrin was removed to obtain chlorohydrin ether.

[0033] In a 5L magnetically stirred autoclave, 420g of chlorohydrin ether, 12.6g of 5% Rh / L molecular sieve hydrogenation catalyst, and 1680g of isopropanol were added. The autoclave was sealed and purged with nitrogen, followed by hydrogen purging. The hydrogenation reaction was then carried out at 80℃ and 7MPa for 2 hours. After the reaction, the catalyst was removed by filtration, the isopropanol was recovered by distillation of the filtrate, and the solvent was removed at 180℃ and 10kPa to obtain chlorohydrin ether.

[0034] 425g of hydrochlorohydrin ether and 300g of toluene were added to a reaction vessel and stirred under nitrogen protection. The mixture was heated to 95℃, and 440g of 20% sodium hydroxide solution was added dropwise over 2 hours. After the addition was complete, the reaction continued for 7 hours. After the reaction was completed, 400g of toluene was added, stirring was stopped, the mixture was allowed to stand, water was separated, phosphoric acid was added dropwise for neutralization, and the aqueous phase was washed until the pH of the aqueous phase was 6.5-7. The organic phase was distilled to recover the toluene, and the solvent was removed at 170℃ and 10kPa to obtain 345g of 2,2′-di(4-hydroxycyclohexyl)propane diglycidyl ether epoxy resin. The obtained product was a colorless, transparent, viscous liquid with an epoxy equivalent of 185g / eq, a hydrolyzable chlorine content of 127μg / g, an inorganic chlorine content of 4μg / g, a total chlorine content of 0.23%, a viscosity of 1816mPas (25℃), and a benzene ring hydrogenation rate of 98.2%.

[0035] Example 2

[0036] 228.3 g of bisphenol A and 740 g of epichlorohydrin were added to a reaction vessel and stirred under nitrogen protection to completely dissolve bisphenol A in epichlorohydrin. The mixture was heated to 60 °C, and 3.5 g of tetrabutylammonium chloride was added. The reaction was carried out at 60 °C for 4 h, and then heated to 100 °C for 1 h. The mixture was washed with water until the pH of the aqueous phase was 6.5-7, and then excess epichlorohydrin was removed to obtain chlorohydrin ether.

[0037] In a 5L magnetically stirred autoclave, 420g of chlorohydrin ether, 16.8g of 3% Rh / L molecular sieve hydrogenation catalyst, and 1260g of isopropanol were added. The autoclave was sealed and purged with nitrogen, followed by hydrogen purging. The hydrogenation reaction was then carried out at 90℃ and 6MPa for 3 hours. After the reaction, the catalyst was removed by filtration, the isopropanol was recovered by distillation of the filtrate, and the solvent was removed at 180℃ and 10kPa to obtain chlorohydrin ether.

[0038] 425g of hydrochlorohydrin ether and 350g of toluene were added to a reaction vessel and stirred under nitrogen protection. The mixture was heated to 90℃, and 335g of 30% sodium hydroxide solution was added dropwise over 1.5h. After the addition was complete, the reaction continued for 6h. After the reaction was complete, 450g of toluene was added, stirring was stopped, the mixture was allowed to stand, water was separated, phosphoric acid was added dropwise for neutralization, and the aqueous phase was washed until the pH of the aqueous phase was 6.5-7. The organic phase was distilled to recover the toluene, and the solvent was removed at 170℃ and 10kPa to obtain 342g of 2,2′-di(4-hydroxycyclohexyl)propane diglycidyl ether epoxy resin. The obtained product was a colorless, transparent, viscous liquid with an epoxy equivalent of 188g / eq, a hydrolyzable chlorine content of 135μg / g, an inorganic chlorine content of 4μg / g, a total chlorine content of 0.24%, a viscosity of 2253mPas (25℃), and a benzene ring hydrogenation rate of 97.5%.

[0039] Example 3

[0040] 228.3 g of bisphenol A and 463 g of epichlorohydrin were added to a reaction vessel and stirred under nitrogen protection to completely dissolve bisphenol A in epichlorohydrin. The mixture was heated to 65 °C, and 4.6 g of tetramethylammonium chloride was added. The reaction was carried out at 65–75 °C for 4 h, and then heated to 95 °C for 1 h. The mixture was washed with water until the pH of the aqueous phase was 6.5–7, and then excess epichlorohydrin was removed to obtain chlorohydrin ether.

[0041] In a 5L magnetically stirred autoclave, 420g of chlorohydrin ether, 12.6g of 5% Rh / L molecular sieve hydrogenation catalyst, and 1680g of isopropanol were added. The autoclave was sealed and purged with nitrogen, followed by hydrogen purging. The hydrogenation reaction was then carried out at 100℃ and 5MPa for 3 hours. After the reaction, the catalyst was removed by filtration, the isopropanol was recovered by distillation of the filtrate, and the solvent was removed at 170℃ and 8kPa to obtain chlorohydrin ether.

[0042] 425g of hydrochlorohydrin ether and 420g of toluene were added to a reaction vessel and stirred under nitrogen protection. The mixture was heated to 100℃, and 440g of 20% sodium hydroxide solution was added dropwise over 2 hours. After the addition was complete, the reaction continued for 10 hours. After the reaction was complete, 380g of toluene was added, stirring was stopped, the mixture was allowed to stand, water was separated, phosphoric acid was added dropwise for neutralization, and the aqueous phase was washed until the pH reached 6.5-7. The organic phase was distilled to recover toluene, and the solvent was removed at 180℃ and 7kPa to obtain 343g of 2,2′-di(4-hydroxycyclohexyl)propane diglycidyl ether epoxy resin. The obtained product was a colorless, transparent, viscous liquid with an epoxy equivalent of 191g / eq, a hydrolyzable chlorine content of 135μg / g, an inorganic chlorine content of 5μg / g, a total chlorine content of 0.25%, a viscosity of 2678mPas (25℃), and a benzene ring hydrogenation rate of 97.7%.

[0043] Example 4

[0044] 228.3 g of bisphenol A and 555 g of epichlorohydrin were added to a reaction vessel and stirred under nitrogen protection to completely dissolve bisphenol A in epichlorohydrin. The mixture was heated to 70 °C, and 2.3 g of benzyltriethylammonium chloride was added. The mixture was then etherified at 80 °C for 4 h, and then heated to 105 °C for 0.5 h. The mixture was washed with water until the pH of the aqueous phase was 6.5–7, and then excess epichlorohydrin was removed to obtain chlorohydrin ether.

[0045] In a 5L magnetically stirred autoclave, 420g of chlorohydrin ether, 4.2g of 10% Rh / L molecular sieve hydrogenation catalyst, and 1680g of isopropanol were added. The autoclave was sealed and purged with nitrogen, followed by hydrogen purging. The hydrogenation reaction was then carried out at 100℃ and 7MPa for 2 hours. After the reaction, the catalyst was removed by filtration, the isopropanol was recovered by distillation of the filtrate, and the solvent was removed at 180℃ and 10kPa to obtain chlorohydrin ether.

[0046] 425g of hydrochlorohydrin ether and 270g of toluene were added to a reaction vessel and stirred under nitrogen protection. The mixture was heated to 95℃, and 440g of 20% sodium hydroxide solution was added dropwise over 2 hours. After the addition was complete, the reaction continued for 8 hours. After the reaction was completed, 600g of toluene was added, stirring was stopped, the mixture was allowed to stand, water was separated, phosphoric acid was added dropwise for neutralization, and the aqueous phase was washed until the pH reached 6.5–7. The organic phase was distilled to recover the toluene, and the solvent was removed at 170℃ and 10kPa to obtain 346g of 2,2′-di(4-hydroxycyclohexyl)propane diglycidyl ether epoxy resin. The obtained product was a colorless, transparent, viscous liquid with an epoxy equivalent of 190g / eq, a hydrolyzable chlorine content of 128μg / g, an inorganic chlorine content of 5μg / g, a total chlorine content of 0.22%, a viscosity of 2525mPas (25℃), and a benzene ring hydrogenation rate of 98.3%.

[0047] Example 5

[0048] 228.3 g of bisphenol A and 555 g of epichlorohydrin were added to a reaction vessel and stirred under nitrogen protection to completely dissolve bisphenol A in epichlorohydrin. The mixture was heated to 65 °C, and 3.2 g of n-pentyltriphenylammonium bromide was added. The reaction was carried out at 65 °C for 3 h, and then heated to 105 °C for 0.5 h. The mixture was washed with water until the pH of the aqueous phase was 6.5-7, and then excess epichlorohydrin was removed to obtain chlorohydrin ether.

[0049] In a 5L magnetically stirred autoclave, 420g of chlorohydrin ether, 12.6g of 5% Rh / L molecular sieve hydrogenation catalyst, and 2380g of isopropanol were added. The autoclave was sealed and purged with nitrogen, followed by hydrogen purging. The hydrogenation reaction was then carried out at 80℃ and 7MPa for 2 hours. After the reaction, the catalyst was removed by filtration, the isopropanol was recovered by distillation of the filtrate, and the solvent was removed at 170℃ and 8kPa to obtain chlorohydrin ether.

[0050] 425g of hydrochlorohydrin ether and 425g of toluene were added to a reaction vessel and stirred under nitrogen protection. The temperature was raised to 95℃, and 440g of 20% sodium hydroxide solution was added dropwise over 2 hours. After the addition was complete, the reaction continued for 9 hours. After the reaction was completed, 430g of toluene was added, stirring was stopped, the mixture was allowed to stand, water was separated, phosphoric acid was added dropwise for neutralization, and the aqueous phase was washed until the pH reached 6.5-7. The organic phase was distilled to recover toluene, and the solvent was removed at 170℃ and 8kPa to obtain 343g of 2,2′-di(4-hydroxycyclohexyl)propane diglycidyl ether epoxy resin. The obtained product was a colorless, transparent, viscous liquid with an epoxy equivalent of 187g / eq, a hydrolyzable chlorine content of 124μg / g, an inorganic chlorine content of 4μg / g, a total chlorine content of 0.24%, a viscosity of 2285mPas (25℃), and a benzene ring hydrogenation rate of 97.8%.

[0051] Comparative Example 1

[0052] This comparative experiment directly used hydrogenated bisphenol A and epichlorohydrin as raw materials to prepare alicyclic epoxy resin by first etherification and then cyclization under the action of a catalyst.

[0053] 240.4 g of hydrogenated bisphenol A and 280 g of toluene were added to a reaction vessel and stirred until the hydrogenated bisphenol A was completely dissolved in the toluene. The mixture was heated to 113 °C and refluxed for dehydration. After dehydration for 1 hour, the mixture was cooled to 100 °C and 0.7 g of boron trifluoride diethyl ether solution was added. 207 g of epichlorohydrin was added dropwise over 2.5 hours. After the addition was complete, the reaction continued for another 0.5 hours. The etherification reaction temperature was maintained at 98–102 °C. After the reaction was completed, 140 g of toluene was recovered by distillation. 270g of pure water was added to the reaction vessel, followed by 210g of a 49% sodium hydroxide aqueous solution over 2 hours at a reaction temperature of 90°C. The reaction was continued for another 8 hours after the addition was complete. After the reaction, 280g of toluene was added, stirring was stopped, the mixture was allowed to stand, water was separated, phosphoric acid was added for neutralization, and the mixture was washed with water until the pH of the aqueous phase reached 6.5–7. The organic phase was distilled to recover the toluene, and the solvent was removed at 170°C and 8 kPa to obtain 369g of 2,2′-di(4-hydroxycyclohexyl)propane diglycidyl ether epoxy resin. The resulting product was a colorless, transparent, viscous liquid with an epoxy equivalent of 228 g / eq, a hydrolyzable chlorine content of 565 μg / g, an inorganic chlorine content of 5 μg / g, a total chlorine content of 3.27%, and a viscosity of 2785 mPas (25°C). It is evident that compared to the present invention, the hydrolyzable chlorine content of the obtained product is significantly increased, and the total chlorine content and epoxy equivalent are much higher than those of the example.

[0054] Comparative Example 2

[0055] This comparative example uses bisphenol A epoxy resin as raw material and directly hydrogenates it to prepare alicyclic epoxy resin.

[0056] 1000g of bisphenol A epoxy resin CYD-128 (Sinopec Baling Petrochemical Company, epoxy equivalent 189g / eq) was dissolved in 3000g of toluene, then washed three times with 900g of deionized water at 60℃, and then the toluene in the solution was removed. The sodium content of the treated bisphenol A epoxy resin was 0.08μg / g.

[0057] In a 2L magnetically stirred autoclave, 150g of pretreated bisphenol A epoxy resin, 1.5g of 5% Rh / L molecular sieve hydrogenation catalyst, and 850g of isopropanol were added. The autoclave was sealed and purged with nitrogen, followed by hydrogen purging. The hydrogenation reaction was then carried out at 100℃ and 6MPa for 3 hours. After the reaction, the catalyst was removed by filtration, and the isopropanol was recovered by distillation of the filtrate. The solvent was removed at 180℃ and 20kPa to obtain a colorless and transparent hydrogenated bisphenol A epoxy resin with an epoxy equivalent of 199g / eq, an epoxy group decomposition rate of 4.8%, a hydrolyzable chlorine content of 206μg / g, an inorganic chlorine content of 5μg / g, a total chlorine content of 0.25%, a viscosity of 3126mPas (25℃), and a benzene ring hydrogenation rate of 97.6%. When bisphenol A epoxy resin is used as a raw material to directly hydrogenate and prepare alicyclic epoxy resin, although the total chlorine content in the product is low, epoxy group decomposition occurs, and the epoxy equivalent of the product is higher than that in the example.

[0058] Comparative Example 3

[0059] The only difference between this comparative example and Example 1 is that the two-stage etherification reaction is not used; instead, etherification is performed directly at 80°C for 3.5 hours, while all other conditions remain the same. 332 g of 2,2′-di(4-hydroxycyclohexyl)propane diglycidyl ether epoxy resin was obtained. The resulting product is a colorless, transparent, viscous liquid with an epoxy equivalent of 210 g / eq, a hydrolyzable chlorine content of 203 μg / g, an inorganic chlorine content of 5 μg / g, a total chlorine content of 0.35%, a viscosity of 3629 mPas (25°C), and a benzene ring hydrogenation rate of 93.1%. When the two-stage etherification reaction is not used, the hydrolyzable chlorine content and liquid viscosity of the resulting product increase significantly, while the benzene ring hydrogenation rate decreases.

[0060] Comparative Example 4

[0061] The only difference between this comparative example and Example 1 is that the etherification reaction uses sodium hydroxide solution as a catalyst instead of a quaternary ammonium salt; 20g of 30% sodium hydroxide solution is added as a catalyst, while all other conditions remain the same. 312g of 2,2′-di(4-hydroxycyclohexyl)propane diglycidyl ether epoxy resin was obtained. The resulting product is a colorless, transparent, viscous liquid with an epoxy equivalent of 218g / eq, a hydrolyzable chlorine content of 402μg / g, an inorganic chlorine content of 5μg / g, a total chlorine content of 0.38%, a viscosity of 4627mPas (25℃), and a benzene ring hydrogenation rate of 72.6%.

Claims

1. A process for the preparation of a cycloaliphatic epoxy resin, characterized in that: Bisphenol A and epichlorohydrin are subjected to a two-stage etherification reaction at low temperature and high temperature under the action of a quaternary ammonium salt catalyst to obtain chlorohydrin ether; the chlorohydrin ether is then subjected to a catalytic hydrogenation reaction and a ring-closing reaction in sequence to obtain the final product. The first stage of the two-stage etherification reaction is carried out at a temperature of 60–80°C for 3–4 hours; the second stage of the two-stage etherification reaction is carried out at a temperature of 95–105°C for 0.5–1 hour; the catalyst used in the catalytic hydrogenation reaction is an Rh / L molecular sieve catalyst; and the closed-ring reaction uses sodium hydroxide aqueous solution and / or potassium hydroxide aqueous solution as a promoter.

2. The method of claim 1, wherein the method is characterized by: The quaternary ammonium salt catalyst is one of n-pentyltriphenylammonium bromide, tetrabutylammonium chloride, tetramethylammonium chloride, and benzyltriethylammonium chloride.

3. The method for preparing an alicyclic epoxy resin according to claim 1, characterized in that: The molar ratio of bisphenol A to epichlorohydrin is 1:5 to 8.

4. The method for preparing an alicyclic epoxy resin according to claim 2 or 3, characterized in that: The mass ratio of bisphenol A to quaternary ammonium salt catalyst is 100:1 to 2.

5. The method for preparing an alicyclic epoxy resin according to claim 1, characterized in that: The conditions for the catalytic hydrogenation reaction are: temperature 60–120°C, pressure 4–8 MPa, and time 1.5–4 h.

6. The method for preparing an alicyclic epoxy resin according to claim 1, characterized in that: The mass ratio of the catalyst to the chlorohydrin ether is 1 to 4:

100.

7. The method for preparing an alicyclic epoxy resin according to claim 1, characterized in that: The molar ratio of the sodium hydroxide aqueous solution and / or potassium hydroxide aqueous solution to hydrochlorohydrin ether is 2.1 to 2.5:

1.

8. The method for preparing an alicyclic epoxy resin according to claim 1, characterized in that: The conditions for the closed-loop reaction are: temperature 90–100℃ and time 7–14h.

9. A method for preparing an alicyclic epoxy resin according to claim 1 or 8, characterized in that: The solvent used in the closed-ring reaction is at least one of toluene, ethylbenzene, xylene, methyl isobutyl ketone, and methyl ethyl ketone.