A method for synthesizing alicyclic epoxy resin

Abstract

The present invention belongs to the preparation technology of epoxy resin, and specifically relates to a new synthesis method of alicyclic epoxy resin. 3,4-epoxycyclohexyl-1-methanol and ester compounds are used as raw materials, and reacted in the presence of a catalyst to obtain alicyclic epoxy resin; the catalyst is one or more of tetraethoxytitanium, tetrabutoxytitanium, dibutyltin dilaurate, diethyltin oxide, and dibutyltin oxide. The present invention avoids the danger of conventional epoxidation reactions and introduces epoxy groups through new reactions. This new idea directly generates special epoxy resins with the help of commonly available and cheap epoxy compounds, reduces the amount of three wastes generated and the total halogen content, and the cost of the process and the EHS feasibility are better achieved.

Description

Technical Field

[0001] The invention belongs to the preparation technology of epoxy resin, and specifically relates to a new synthesis method of alicyclic epoxy resin. Background Art

[0002] The epoxy group in the structure of alicyclic epoxy resin is directly connected to the alicyclic ring, the structure is stable and the alicyclic ring is in a saturated state, so the resin formed has good weather resistance, UV resistance, excellent electrical insulation performance, good thermal stability, excellent process performance, high safety factor and other characteristics. As a diluent, it is widely used in insulating potting materials, composite materials, coatings, adhesives, and light curing. At present, the scheme for obtaining epoxy groups in alicyclic epoxy resins often uses peroxides to epoxidize carbon-carbon double bonds. Patent application US006075155A reports various conditions for epoxidation reactions. The epoxidation reagents involved include peracetic acid, peroxyphosphotungstate, etc. Most of them are high-energy compounds and are relatively dangerous when used; Patent application CN202010225333.X reports the use of a microreactor for continuous reaction and the use of low-concentration hydrogen peroxide for epoxidation reaction to further reduce the danger of epoxidation reaction, but the equipment used is complex; how to better reduce the danger of the reaction has become the research focus of the industrialization of epoxidation process. Summary of the invention

[0003] The prior art uses 3-cyclohexene-1-methanol and (meth) methyl (or ethyl) acrylate as raw materials to prepare the intermediate (meth) acrylate-3-cyclohexenyl methyl ester, and then uses potassium persulfate as an oxidant and low-carbon ketone as a reaction medium to carry out a selective epoxidation reaction of carbon-carbon double bonds under relatively mild reaction conditions; this method synthesizes the substrate of the epoxidation reaction, and the epoxy resin is subsequently prepared by the epoxidation method, and there are still dangers in the production process. The present invention avoids the dangers of conventional epoxidation reactions and introduces epoxy groups through a new reaction. This new idea uses commonly available and cheap epoxy compounds to directly generate special epoxy resins, reduces the amount of three wastes generated and the total halogen content, and the cost of the process and the EHS feasibility are better achieved.

[0004] The present invention adopts the following technical solution:

[0005] A method for synthesizing an alicyclic epoxy resin comprises taking 3,4-epoxycyclohexyl-1-methanol and an ester compound as raw materials and reacting them in the presence of a catalyst to obtain the alicyclic epoxy resin.

[0006] In the present invention, the chemical structural formula of the ester compound is as follows:

[0007]

[0008] Where n is the number of arms, ranging from 1 to 4; R is one of the following structures:

[0009]

[0010] The dotted lines represent substitution positions, and their number is consistent with n.

[0011] In the present invention, the catalyst is one or more of tetraethoxytitanium, tetrabutoxytitanium, dibutyltin dilaurate, diethyltin oxide, and dibutyltin oxide.

[0012] In the present invention, no oxidizing agent is required for the reaction.

[0013] Preferably, when the ester compound is an acrylic ester compound, the raw material contains a polymerization inhibitor, such as phenothiazine.

[0014] In the present invention, for the monoester compound (n=1), the molar ratio of 3,4-epoxycyclohexyl-1-methanol, the ester compound, and the catalyst is 1:(1.5-2.5):(0.01-0.05), preferably 1:(1.8-2.2):(0.02-0.04); for the diester compound (n=2), the molar ratio of 3,4-epoxycyclohexyl-1-methanol, the ester compound, and the catalyst is (2.8-4.0):1:(0.02-0.08), preferably (3.0-3.3):1:(0.04-0.06).

[0015] In the present invention, the reaction temperature is 100° C. to 110° C., and the reaction time is 5 to 6 hours. After the reaction is completed, the reaction is distilled under reduced pressure to obtain an alicyclic epoxy resin.

[0016] The present invention uses 3,4-epoxycyclohexyl-1-methanol to directly generate corresponding epoxy resin, uses the ester to be reacted and the generated epoxy resin itself as solvent, does not introduce other solvents, uses molecular distillation to perform low-temperature distillation on heat-sensitive acrylic resin to obtain the product, and uses alkoxy titanium and organic tin catalysts in the process, thereby avoiding the use of solvents and oxidants in the prior art.

[0017] The present invention avoids the danger of conventional epoxidation reactions and introduces epoxy groups through a new reaction. This new idea directly generates special epoxy resins using commonly available and inexpensive epoxy compounds, reduces the amount of three wastes generated and the total halogen content, and better achieves process costs and EHS feasibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The nuclear magnetic hydrogen spectrum (CDCl 3 ,400MHz).

[0019] Figure 2The nuclear magnetic hydrogen spectrum (CDCl 3 ,400MHz).

[0020] Figure 3 The nuclear magnetic hydrogen spectrum (CDCl 3 ,400MHz).

[0021] Figure 4 The nuclear magnetic hydrogen spectrum (CDCl 3 ,400MHz). DETAILED DESCRIPTION

[0022] The present invention discloses a method for synthesizing a cycloaliphatic epoxy resin, which uses 3,4-epoxycyclohexyl-1-methanol to directly exchange with an ester to generate a corresponding epoxy resin, without the need for an oxidant and a solvent, and can obtain the product in high yield. The reaction diagram is as follows:

[0023]

[0024] R is one of the following groups:

[0025]

[0026] According to the invention, monofunctional alicyclic epoxy resin and difunctional alicyclic epoxy resin can be obtained when n is 1 to 2. The raw material 3,4-epoxycyclohexyl-1-methanol is an existing compound.

[0027] The present invention provides a new idea for synthesizing special epoxy resins. The method uses 3,4-epoxycyclohexyl-1-methanol and methyl ester to synthesize the corresponding epoxy resin through an ester exchange reaction, and the catalyst is an alkoxy titanium compound, a dialkyl tin compound, a quaternary ammonium alcohol salt, etc. The purpose of the present invention is to develop a new method for synthesizing special epoxy resins, which has the characteristics of easy availability of corresponding raw materials, simple operation, rapid reaction and high yield, overcomes the dangers caused by the use of high-energy compounds such as peroxyacids, peroxysalts, hydrogen peroxide in traditional methods, and overcomes the shortcomings of excessive halogens caused by the use of halogenated solvents.

[0028] The compounds used in the present invention are all existing products, and the specific preparation operations and testing methods are all conventional techniques. Unless otherwise specified, the yield is a molar yield.

[0029] Embodiment 1

[0030]

[0031] 128.17 kg 3,4-epoxycyclohexyl-1-methanol, 200.23 kg methyl methacrylate, 9.61 kg tetrabutoxytitanium, and 1.28 kg phenothiazine were added to a 500 L reactor, and the temperature was raised to 95° C. to start distilling out the methanol-methyl methacrylate mixture, which was kept warm for 0.5 h, and then reacted at 105° C. for 5 hours (at this time, no obvious liquid was distilled out, and the 3,4-epoxycyclohexyl-1-methanol content was ≤1.0 wt % when the sampling GC was taken), and the reaction was stopped; the reaction solution was vacuumed at 2000 Pa The excess methyl methacrylate was removed by reduced pressure distillation at 80°C, and the concentrated solution was distilled at 2Pa ​​vacuum degree at 55°C to obtain 186.7kg of 3,4-epoxycyclohexylmethyl methacrylate with a molar yield of 93.1%; purity of 97.5%; epoxy equivalent: 201.04g / mol, viscosity 10.8CP; the molar ratio of the above 3,4-epoxycyclohexyl-1-methanol, methyl methacrylate and tetrabutoxytitanium was 1:2:0.03.

[0032] Embodiment 2

[0033]

[0034] 128.17 kg 3,4-epoxycyclohexyl-1-methanol, 172.18 kg methyl acrylate, 9.61 kg tetrabutoxytitanium, and 1.28 kg phenothiazine were added to a 500 L reactor, and the temperature was raised to 98° C. to start distilling out a methanol-methyl acrylate mixture, which was kept warm for 0.5 h, and then reacted at 105° C. for 5 hours, and the reaction was stopped; the reaction solution was subjected to reduced pressure distillation at 80° C. at a vacuum degree of 2000 Pa to remove excess methyl acrylate, and the concentrated solution was subjected to molecular distillation at a vacuum degree of 2 Pa at a reduced pressure distillation of 55° C. to obtain 167.6 kg 3,4-epoxycyclohexyl methacrylate, with a molar yield of 92.0%; a purity of 96.7%; an epoxy equivalent of 192.7 g / mol, and a viscosity of 9.9 CP; the molar ratio of the above 3,4-epoxycyclohexyl-1-methanol, methyl acrylate, and tetrabutoxytitanium was 1:2:0.03.

[0035] On the basis of Example 2, the molar ratio of raw materials and the reaction time were changed, and the results are shown in Table 1.

[0036] Table 1 Different raw material molar ratios and reaction times

[0037]

[0038]

[0039] On the basis of Example 2, the raw material catalyst selection and reaction time were changed, and the results are shown in Table 2.

[0040] Table 2 Different catalysts, reaction time

[0041]

[0042] Embodiment 3

[0043]

[0044] Add 128.17 kg 3,4-epoxycyclohexyl-1-methanol and 312.36 kg 3,4-epoxycyclohexyl-1-methyl carboxylate and 9.61 kg of tetrabutoxytitanium were reacted at 100° C. for 7 hours (no obvious liquid was evaporated at this time, and the content of 3,4-epoxycyclohexyl-1-methanol was ≤1.0 wt % when the sample was taken by GC), and the reaction was stopped; the reaction solution was subjected to reduced pressure distillation at 95° C. at a vacuum degree of 500 Pa to remove excess 3,4-epoxycyclohexyl-1-methyl carboxylate, and the concentrated solution was subjected to molecular distillation at a vacuum degree of 2 Pa at a reduced pressure distillation degree of 144° C. to obtain 249.5 kg of 3,4-epoxycyclohexylcarboxylic acid-3,4-epoxycyclohexylmethyl ester, with a molar yield of 99.0%; purity of 98.2%; epoxy equivalent: 131 g / mol, viscosity 242 CP; the molar ratio of the above-mentioned 3,4-epoxycyclohexyl-1-methanol, 3,4-epoxycyclohexyl-1-methyl carboxylate and tetrabutoxytitanium was 1:2:0.03.

[0045] Embodiment 4

[0046]

[0047] Add 369.13 kg into the 500L reactor 3,4-epoxycyclohexyl-1-methanol, 167.23kg dimethyl adipate, 18.5kg tetrabutoxytitanium; react at 105°C for 8 hours (no obvious liquid evaporated at this time, sampling GC detection 3,4-epoxycyclohexyl-1-methanol content ≤1.0wt%), stop the reaction; the reaction solution is vacuum distilled at 300Pa and 105°C to remove excess 3,4-epoxycyclohexyl-1-methanol, and the concentrated solution is molecularly distilled at 2Pa ​​and 198°C to obtain 317.0kg of bis((3,4-epoxycyclohexyl)methyl)adipate, with a molar yield of 90.1%; purity: 98.2%; epoxy equivalent: 185g / mol, viscosity 575CP; the molar ratio of the above 3,4-epoxycyclohexyl-1-methanol, dimethyl adipate, and tetrabutoxytitanium is 3:1:0.06.

[0048] Figure 1 The nuclear magnetic hydrogen spectrum (CDCl 3 ,400MHz). Figure 2 The nuclear magnetic hydrogen spectrum (CDCl 3 ,400MHz). Figure 3The nuclear magnetic hydrogen spectrum (CDCl 3 ,400MHz). Figure 4 The nuclear magnetic hydrogen spectrum (CDCl 3 , 400MHz). Cycloaliphatic epoxy resins are usually obtained by epoxidation reaction using double bonds. The commonly used oxidant is peracid, or phase transfer catalyst combined with hydrogen peroxide oxidation. Peracid has a high risk factor, and a large amount of wastewater will be generated during the post-reaction treatment process. The acidic reaction system will also cause corrosion to equipment pipelines. At the same time, chloroalkanes are often used as solvents in epoxidation reactions, and their residues often lead to excessive halogen residues in epoxy resins, limiting the application of epoxy resins in the electronics industry. The present invention uses a new method to prepare cycloaliphatic epoxy resins, which simplifies the operation, reduces the risk of the reaction, and reduces the total halogen content.

Claims

1. A method for synthesizing an alicyclic epoxy resin, characterized in that: 3,4-epoxycyclohexyl-1-methanol and an ester compound are used as raw materials and reacted in the presence of a catalyst to obtain an alicyclic epoxy resin; the catalyst is tetrabutoxytitanium; the ester compound is methyl methacrylate, methyl acrylate, 3,4-epoxycyclohexyl-1-methyl carboxylate or dimethyl adipate; for the monoester compound, the molar ratio of 3,4-epoxycyclohexyl-1-methanol, the ester compound and the catalyst is 1:(1.5-2.5):(0.01-0.05); for the diester compound, the molar ratio of 3,4-epoxycyclohexyl-1-methanol, the ester compound and the catalyst is (2.8-4.0):1:(0.02-0.08); the reaction temperature is 100°C-110°C and the reaction time is 5-6 hours.

2. The method for synthesizing alicyclic epoxy resin according to claim 1, characterized in that: The reaction does not require an oxidizing agent.

3. The method for synthesizing alicyclic epoxy resin according to claim 1, characterized in that: When the ester compound is an acrylic acid ester compound, the raw material contains a polymerization inhibitor.

Images