Diethyltoluenediamine epoxy resin, preparation method thereof and modified epoxy resin

Abstract

The invention provides diethyltoluenediamine epoxy resin, a preparation method thereof and modified epoxy resin, and belongs to the technical field of resin materials. The diethyltoluenediamine epoxy resin provided by the invention has a structure as shown in a formula I. The structure of the DETGA provided by the invention contains a rigid benzene ring structure and a flexible ethyl structure, so that the rigid strength and toughness of an epoxy system can be improved; meanwhile, DETGA has multiple epoxy groups and is similar to E-51 bisphenol A epoxy resin in structure, so that DETGA can be uniformly dispersed in a system; the epoxy value of the diethyltoluenediamine epoxy resin provided by the invention is greater than or equal to 0.80 eq / 100g, the viscosity is less than or equal to 4000 mPa.s, and the rigidity, toughness, high temperature resistance and processability of an E-51 epoxy resin cured product can be improved after the diethyltoluenediamine epoxy resin is doped into an E-51 epoxy resin system. # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the technical field of resin materials, and in particular relates to a diethyltoluenediamine epoxy resin and a preparation method thereof, and a modified epoxy resin. Background Art

[0002] Epoxy resin (EP) has been widely used in electrical insulation materials, adhesives, coatings, electronic packaging and casting due to its low cost and excellent performance. However, general-purpose bisphenol A epoxy resin E-51 often does not have the performance of high modulus composite materials and sufficient heat resistance, and its own high viscosity and other problems limit its application in high-tech fields. Generally, adding inhibitors, fillers, nanomaterials, etc. to epoxy resin systems is an effective way to improve the heat resistance and mechanical properties of epoxy resins. However, these methods usually further increase the viscosity of the system and cause serious operational problems. Based on the general correlation between resin structure and performance, it can be found that higher crosslinking density can effectively improve the mechanical properties and heat resistance of the resin, so the development of multifunctional epoxides is one of the most effective ways to achieve this requirement. Among them, glycidylamine epoxy resin has the characteristics of multiple epoxy functionalities and high epoxy value. It can form a highly cross-linked three-dimensional network structure with acid anhydride and aromatic amine curing agents at an appropriate temperature. Its cured product has a high cross-linking density, excellent mechanical properties and good heat resistance. It can effectively improve the mechanical properties and heat resistance of bisphenol A epoxy resin and has attracted much attention.

[0003] In the prior art, N,N,N′,N′-tetraglycidylamine-4,4′-diaminodiphenylmethane (TGDDM) is generally used as a typical representative of multifunctional amine epoxides, but it still has certain shortcomings, such as high viscosity (10000-12000 mPa·s (25°C)), easy self-crosslinking, poor processability and hard and brittle cured products, etc., which limits its application in some occasions. Summary of the invention

[0004] The purpose of the present invention is to provide a diethyltoluenediamine epoxy resin and a preparation method thereof, and a modified epoxy resin. The diethyltoluenediamine epoxy resin prepared by the present invention has low viscosity, is not easy to self-crosslink, and has excellent processability.

[0005] In order to achieve the purpose of the present invention, the present invention provides the following technical solutions:

[0006] A diethyltoluenediamine epoxy resin having a structure shown in Formula I:

[0007]

[0008] Preferably, the epoxy value of the diethyltoluenediamine epoxy resin is ≥0.80eq / 100g, and the viscosity is ≤4000mPa·s.

[0009] The present invention also provides a method for preparing the diethyltoluenediamine epoxy resin described in the above technical solution, comprising the following steps:

[0010] Diethyltoluenediamine, epichlorohydrin, a promoter and a phase transfer catalyst are mixed and subjected to a ring-opening reaction to obtain an intermediate product having a structure shown in formula II;

[0011]

[0012] The intermediate product is mixed with an inorganic alkali solution to carry out a ring-closing reaction to obtain the diethyltoluenediamine epoxy resin.

[0013] Preferably, the promoter is an alcohol reagent; and the phase transfer catalyst is a quaternary ammonium salt.

[0014] Preferably, the inorganic base in the inorganic base solution is an alkali metal hydroxide.

[0015] Preferably, the molar ratio of diethyltoluenediamine to epichlorohydrin is 1:4 to 10;

[0016] The mass of the accelerator is 1 to 40% of the mass of diethyltoluenediamine;

[0017] The mass of the phase transfer catalyst is 0.05-0.5% of the total mass of diethyltoluenediamine, epichlorohydrin and the inorganic base;

[0018] The molar ratio of the diethyltoluenediamine to the inorganic base in the inorganic base solution is 1:4-5.

[0019] Preferably, the ring-opening reaction is carried out at a temperature of 30 to 130° C. and for a time of 2 to 8 hours.

[0020] Preferably, the temperature of the ring-closing reaction is 30-100° C., and the time is 0.5-5 h.

[0021] The present invention also provides a modified epoxy resin, which is a modified epoxy resin using the diethyltoluenediamine epoxy resin described in the above technical solution or the diethyltoluenediamine epoxy resin prepared by the preparation method described in the above technical solution as a modifier.

[0022] Preferably, the following components are included:

[0023] Epoxy resin;

[0024] Diethyltoluenediamine epoxy resin accounting for 5 to 20% by mass of the epoxy resin;

[0025] A curing agent that matches the total epoxy value of the epoxy resin and the diethyltoluenediamine epoxy resin.

[0026] The present invention provides a diethyltoluenediamine epoxy resin having a structure shown in Formula I. The diethyltoluenediamine epoxy resin (DETGA) provided by the present invention contains a rigid benzene ring structure and a flexible ethyl structure, which can improve the rigidity and toughness of the epoxy system; at the same time, since DETGA has multiple epoxy groups, it is similar to the structure of E-51 bisphenol A type epoxy resin and can be uniformly dispersed in the system; and the diethyltoluenediamine epoxy resin provided by the present invention has an epoxy value of ≥0.80eq / 100g and a viscosity of ≤4000mPa·s, and can be added to the E-51 epoxy resin system to improve the rigidity, toughness and high temperature resistance of the epoxy resin cured product.

[0027]

[0028] The present invention also provides a method for preparing the epoxy resin described in the above technical scheme. The present invention uses diethyltoluenediamine as a raw material for modification, adopts a "two-step method" (ring-opening reaction and ring-closing reaction) for preparation, and coordinates and controls the ratio of each raw material, the temperature and time of the ring-opening reaction and the ring-closing reaction to ensure the epoxidation degree of the raw material, and obtains a diethyltoluenediamine epoxy resin with an epoxide value of ≥0.80eq / 100g and a viscosity of ≤4000mPa·s. The raw material source for the preparation is wide, the operation is simple, and the method is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0030] Figure 1 IR spectra of diethyltoluenediamine and the diethyltoluenediamine epoxy resin obtained in Example 1;

[0031] Figure 2 1 is the H NMR spectrum of diethyltoluenediamine and the diethyltoluenediamine epoxy resin obtained in Example 1;

[0032] Figure 3 The scanning electron microscope images of the impact fracture surfaces of pure E-51 epoxy resin and modified E-51 epoxy resin with 10 wt% diethyltoluenediamine epoxy resin added;

[0033] Figure 4 It is the thermal weight loss curve of pure E-51 epoxy resin and modified E-51 epoxy resin with 10wt% diethyltoluenediamine epoxy resin added;

[0034] Figure 5This is a storage stability test diagram of the diethyltoluenediamine epoxy resin obtained in Example 1. DETAILED DESCRIPTION

[0035] The present invention provides a diethyltoluenediamine epoxy resin having a structure shown in Formula I:

[0036]

[0037] In the present invention, the epoxy value of the diethyltoluenediamine epoxy resin is ≥0.80eq / 100g, and in a specific embodiment, it can be 0.81eq / 100g, 0.82eq / 100g, 0.83eq / 100g, 0.85eq / 100g or 0.88eq / 100g; the viscosity is ≤4000mPa·s, and in a specific embodiment, it can be 3400mPa·s, 3500mPa·s, 3600mPa·s or 3800mPa·s.

[0038] The diethyltoluenediamine epoxy resin of the present invention is a diethyltoluenediamine epoxy resin monomer.

[0039] The present invention also provides a method for preparing the diethyltoluenediamine epoxy resin described in the above technical solution, comprising the following steps:

[0040] Mixing diethyltoluenediamine, epichlorohydrin, a promoter and a phase transfer catalyst, and performing a ring-opening reaction to obtain an intermediate product with a structure shown in formula II;

[0041] The intermediate product is mixed with an inorganic alkali solution to carry out a ring-closing reaction to obtain the diethyltoluenediamine epoxy resin.

[0042] In the present invention, unless otherwise specified, all preparation raw materials are preferably commercially available products well known to those skilled in the art.

[0043] In the present invention, the promoter is an alcohol reagent, and the alcohol reagent can be a low-carbon alcohol reagent; the low-carbon alcohol reagent can be one or more of methanol, ethanol, isopropanol, isobutanol, n-propanol and n-butanol. In a specific embodiment, it can be isopropanol or ethanol, and the ethanol is anhydrous ethanol. In the present invention, the promoter can help catalyze the ring-opening reaction.

[0044] In the present invention, the phase transfer catalyst is a quaternary ammonium salt; the quaternary ammonium salt may be one or more of benzyltriethylammonium chloride (BTEAC), benzyltrimethylammonium chloride (BTMAC), tetrabutylammonium bromide (TBAB), tetrabutylammonium chloride (TBAC), tetrabutylammonium hydrogen sulfate, trioctylmethylammonium chloride, dodecyltrimethylammonium chloride and tetradecyltrimethylammonium chloride. In a specific embodiment, it may be benzyltriethylammonium chloride, tetrabutylammonium bromide or tetrabutylammonium chloride.

[0045] In the present invention, the inorganic base in the inorganic base solution is an alkali metal hydroxide; in a specific embodiment, the inorganic base solution can be a NaOH solution and / or a KOH solution; the concentration of the inorganic base in the inorganic base solution can be 20-40wt%, and in a specific embodiment, it can be 25wt%, 30wt%, 32wt%, 35wt% or 38wt%.

[0046] In the present invention, the molar ratio of diethyltoluenediamine (DETDA) to epichlorohydrin (ECH) can be 1:4-10, and in a specific embodiment, it can be 1:5, 1:6 or 1:8; the mass of the accelerator can be 1-40% of the mass of diethyltoluenediamine, and in a specific embodiment, it can be 5%, 10%, 20% or 30%; the mass of the phase transfer catalyst can be 0.05-0.5% of the total mass of diethyltoluenediamine, epichlorohydrin and inorganic base, and in a specific embodiment, it can be 0.1%, 0.15%, 0.2% or 0.3%; the molar ratio of diethyltoluenediamine to the inorganic base in the inorganic base solution can be 1:4-5, and in a specific embodiment, it can be 1:4.1, 1:4.2, 1:4.3 or 1:4.5.

[0047] In the present invention, the diethyltoluenediamine, epichlorohydrin, accelerator and phase transfer catalyst are mixed in a manner that: diethyltoluenediamine, epichlorohydrin and accelerator are mixed evenly, and then epichlorohydrin is added dropwise. In the present invention, the dropwise addition time of epichlorohydrin can be 0.5 to 6 hours, and in a specific embodiment, it can be 1 hour, 2 hours, 3 hours or 5 hours. The epichlorohydrin of the present invention is added dropwise, which has the advantage of a stable reaction, and can prevent a sudden temperature rise caused by a violent ring-opening reaction, which affects product quality and causes danger.

[0048] In the present invention, the temperature of the ring-opening reaction can be 30-130°C, and in a specific embodiment, can be 50°C, 70°C, 90°C or 110°C; the time can be 2-8h, and in a specific embodiment, can be 3h, 5h, 6h or 7h. In the present invention, the temperature is raised to the ring-opening reaction temperature, and epichlorohydrin is added dropwise to carry out the ring-opening reaction. The present invention has no particular limitation on the heating rate for raising the temperature to the temperature required for the ring-opening reaction.

[0049] In the present invention, the temperature of the ring-closing reaction can be 30 to 100°C, and in a specific embodiment, can be 50°C, 60°C, 70°C or 90°C; the time can be 0.5 to 5h, and in a specific embodiment, can be 1h, 2h, 3h or 4h. In the present invention, after the ring-opening reaction, the temperature is lowered to the temperature required for the ring-closing reaction, and an inorganic alkali solution is added to carry out the ring-closing reaction. The present invention does not specifically limit the cooling rate to the temperature required for the ring-closing reaction.

[0050] In the present invention, the ring-closing reaction further includes refining; the refining includes the following steps: solid-liquid separation of the product liquid obtained from the ring-closing reaction to obtain a liquid component; layering the liquid component to obtain an organic phase and a brine phase; washing, neutralizing and distilling the organic phase in sequence to obtain the diethyltoluenediamine epoxy resin.

[0051] The present invention has no special limitation on the solid-liquid separation, and a solid-liquid separation method familiar to those skilled in the art can be used. In a specific embodiment, it can be filtration, suction filtration or centrifugal separation. In the present invention, the neutralizing agent used for the neutralization includes one or more of sodium dihydrogen phosphate, potassium dihydrogen phosphate and acetic acid, and in a specific embodiment, it can be sodium dihydrogen phosphate; the present invention has no special limitation on the amount of the neutralizing agent; the present invention is neutralized to a pH value of 7 to 8, and in a specific embodiment, it can be 7.3 or 7.5. The present invention has no special limitation on the conditions of the distillation, and it can be used to completely recover the organic solvent and unreacted epichlorohydrin.

[0052] The present invention has no particular limitation on the device used for preparing the diethyltoluenediamine epoxy resin, and a reaction device well known to those skilled in the art can be used. In a specific embodiment, the "two-step method" (ring-opening reaction and ring-closing reaction) can be carried out in a four-necked flask; the four-necked flask is equipped with a mechanical stirrer with a mechanical seal, a reflux condenser and a thermometer.

[0053] The invention adopts a "two-step method" (ring-opening reaction and ring-closing reaction) for preparation, and coordinately controls the ratio of each raw material, the temperature, time and pressure of the ring-opening reaction and the ring-closing reaction to ensure the epoxidation degree of the raw material, and obtains a diethyltoluenediamine epoxy resin with an epoxide value of ≥0.80eq / 100g and a viscosity of ≤4000mPa·s.

[0054] The present invention also provides a modified epoxy resin, which is the diethyltoluenediamine epoxy resin described in the above technical solution or the diethyltoluenediamine epoxy resin modified epoxy resin prepared by the preparation method of the above technical solution.

[0055] In the present invention, the modified epoxy resin comprises the following components:

[0056] Epoxy resin;

[0057] The diethyltoluenediamine epoxy resin accounts for 5 to 20% of the epoxy resin by mass;

[0058] A curing agent that matches the total epoxy value of the epoxy resin and the diethyltoluenediamine epoxy resin.

[0059] In the present invention, the epoxy resin may be a bisphenol A epoxy resin. In a specific embodiment, the bisphenol A epoxy resin may be E-51 bisphenol A epoxy resin. The curing agent may be 4,4'-diaminodiphenylmethane.

[0060] In the present invention, the mass of the diethyltoluenediamine epoxy resin accounts for 5-20% of the mass of the bisphenol A epoxy resin. In a specific embodiment, it can be 8%, 10%, 12% or 15%.

[0061] In the present invention, the curing agent matches the total epoxy value of the epoxy resin and the diethyltoluenediamine epoxy resin. In a specific embodiment, the amount of the curing agent is calculated by the formula II as follows:

[0062] G = (M × E) / Hn Formula II;

[0063] In formula II: G is the number of grams of curing agent required for 100g of epoxy resin, g; M is the molecular weight of the curing agent, g / mol; E is the epoxy value of the epoxy resin, eq / 100g; Hn is the total number of active hydrogens in the curing agent molecule.

[0064] In the present invention, the preparation method of the modified epoxy resin comprises the following steps:

[0065] The diethyltoluenediamine epoxy resin, epoxy resin and curing agent are mixed and cured to obtain the modified epoxy resin.

[0066] In the present invention, the curing is graded curing, which includes sequentially performing first curing, second curing and third curing; the temperature of the first curing is 100-120°C, which can be 110°C or 115°C in a specific embodiment, and the time is 1-3h, which can be 2h or 2.5h in a specific embodiment; the temperature of the second curing is 130-140°C, which can be 135°C or 138°C in a specific embodiment, and the time is 1-3h, which can be 2h or 2.5h in a specific embodiment; the temperature of the third curing is 150-160°C, which can be 155°C or 158°C in a specific embodiment, and the time is 1-3h, which can be 2h or 2.5h in a specific embodiment.

[0067] In the present invention, the curing further includes aging for 5 to 10 days; the aging temperature can be room temperature; the aging time can be 5 to 10 days, and in a specific embodiment, it can be 6 days, 7 days or 8 days.

[0068] In order to further illustrate the present invention, the diethyltoluenediamine epoxy resin and its preparation method and modified epoxy resin provided by the present invention are described in detail below in conjunction with the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0069] The raw material parameters used in the following examples of the present invention are as follows:

[0070] Diethyltoluenediamine, tetrabutylammonium bromide, tetrabutylammonium chloride, benzyltriethylammonium chloride, anhydrous ethanol, isopropyl alcohol, sodium hydroxide, potassium hydroxide, epichlorohydrin, E-51 bisphenol A epoxy resin, and 4,4'-diaminodiphenylmethane were industrial grade and were sourced from Anhui Xinyuan Technology Co., Ltd.;

[0071] Hydrochloric acid, acetone, xylene, and toluene were of analytical grade and were sourced from Nanjing Chemical Reagent Co., Ltd.

[0072] Example 1

[0073] Weigh 89.0g of diethyltoluenediamine, 17.8g of anhydrous ethanol and 0.89g of benzyltriethylammonium chloride into a four-necked flask equipped with a reflux condenser, a thermometer and a constant pressure dropping funnel, raise the temperature to 80°C, and add 203.5g of ECH, add dropwise for 1 hour, carry out ring-opening reaction at 80°C and normal pressure for 2 hours, cool to 40°C, add 256.3g of 32wt% NaOH aqueous solution dropwise within 1 hour, keep warm at 40°C and normal pressure for 1 hour of ring-closing reaction, filter the product after the reaction, separate the filtrate, remove the brine phase, add sodium dihydrogen phosphate to the organic phase for neutralization, wash with water, control the vacuum degree to -0.09MPa and the kettle temperature to ≤130°C to distill and recover the epichlorohydrin in the organic phase to obtain diethyltoluenediamine epoxy resin, and use the hydrochloric acid-acetone method to detect the epoxy value, which is 0.85eq / 100g; the viscosity is 3400mPa·s.

[0074] The FTIR test was performed using the American Nicolet FTIR-360 Fourier transform infrared spectrometer. Specifically, the potassium bromide coating method was used with a measurement range of 400 to 4000 cm -1 , the results are as follows Figure 1 shown.

[0075] Figure 1 The infrared spectra of diethyltoluenediamine and the diethyltoluenediamine epoxy resin obtained in Example 1, wherein (a) is diethyltoluenediamine, (b) is diethyltoluenediamine epoxy resin, and Figure 1 It can be seen that 3456.9cm -1 、3372.8cm -1 The peak at 3456.9cm is the NH stretching vibration absorption peak on the amino chain of the raw material DETDA. In the infrared spectrum of DETGA, the original peak at 3456.9cm -1 、3372.8cm -1 The peak at 909cm -1The characteristic absorption peak of epoxy group appeared at , indicating that DETDA successfully underwent epoxidation reaction.

[0076] The structure was characterized by Burker Fourier TrnasofmrAVANCE600 spectrometer, and the characterization solvent was deuterated chloroform. The results are as follows Figure 2 shown.

[0077] Figure 2 is the nuclear magnetic hydrogen spectrum of diethyltoluenediamine and the diethyltoluenediamine epoxy resin obtained in Example 1, Figure 2 It can be seen that 1 In the H NMR spectrum, DETGA showed peaks of hydrogen in the methylene group connected to the epoxy group at δ=3.33ppm and δ=3.58ppm, and peaks of hydrogen in the methine group on the epoxy group at δ=2.54ppm, while peaks at δ=2.60ppm and δ=2.35ppm were hydrogen in the methylene group of the epoxy group. 1 The H NMR spectrum showed that the product DETGA was successfully synthesized.

[0078] Based on the analysis of infrared spectrum and nuclear magnetic hydrogen spectrum data, it can be known that the main component structural formula of diethyltoluenediamine epoxy resin is as shown in Formula I.

[0079] Example 2

[0080] 89.0 g of diethyltoluenediamine, 8.9 g of anhydrous ethanol and 0.89 g of tetrabutylammonium bromide were weighed and added into a four-necked flask equipped with a reflux condenser, a thermometer and a constant pressure dropping funnel. The temperature was raised to 70° C., 222 g of ECH was added dropwise, and the addition was completed within 1 h. The ring-opening reaction was carried out at 70° C. and normal pressure for 2 h. The temperature was lowered to 30° C., 336 g of a 25 wt% NaOH aqueous solution was added dropwise, and the addition was completed within 1 h. The ring-closing reaction was kept at 30° C. and normal pressure for 1 h. After the reaction was completed, the obtained product was filtered, and the filtrate obtained by filtration was layered to remove the brine phase. Sodium dihydrogen phosphate was added to the organic phase for neutralization, washed with water, and the vacuum degree was controlled to be -0.09 MPa and the kettle temperature was ≤130° C. to distill and recover the epichlorohydrin in the organic phase to obtain diethyltoluenediamine epoxy resin with an epoxide value of 0.83 eq / 100 g and a viscosity of 3600 mPa·s.

[0081] Example 3

[0082] 89.0g of diethyltoluenediamine, 8.9g of isopropanol and 0.45g of benzyltetrabutylammonium chloride were weighed and added into a four-necked flask equipped with a reflux condenser, a thermometer and a constant pressure dropping funnel. The temperature was raised to 70°C, 194.3g of ECH was added dropwise, and the addition was completed within 1h. The ring-opening reaction was carried out at 70°C and normal pressure for 6h. The temperature was lowered to 50°C, and 205g of a 40wt% NaOH aqueous solution was added dropwise, and the addition was completed within 1h. The ring-closing reaction was kept at 50°C and normal pressure for 1h. After the reaction was completed, the obtained product was filtered, and the filtrate obtained by filtration was layered to exclude the brine phase. Sodium dihydrogen phosphate was added to the organic phase for neutralization, washed with water, and the vacuum degree was controlled to be -0.09MPa and the kettle temperature was ≤130°C to distill and recover the epichlorohydrin in the organic phase to obtain diethyltoluenediamine epoxy resin with an epoxide value of 0.81eq / 100g and a viscosity of 3500mPa·s.

[0083] Example 4

[0084] 89.0g of diethyltoluenediamine, 8.9g of isopropanol and 1.8g of benzyltetrabutylammonium chloride were weighed and added into a four-necked flask equipped with a reflux condenser, a thermometer and a constant pressure dropping funnel. The temperature was raised to 90°C, 222g of ECH was added dropwise, and the addition was completed within 1h. The ring-opening reaction was carried out at 90°C and normal pressure for 6h. The temperature was lowered to 50°C, and 256.3g of a 32wt% NaOH aqueous solution was added dropwise, and the addition was completed within 1h. The ring-closing reaction was kept at 50°C and normal pressure for 1h. After the reaction was completed, the obtained product was filtered, and the filtrate obtained by filtration was layered to remove the brine phase. Sodium dihydrogen phosphate was added to the organic phase for neutralization, washed with water, and the vacuum degree was controlled to be -0.09MPa and the kettle temperature was ≤130°C to distill and recover the epichlorohydrin in the organic phase to obtain diethyltoluenediamine epoxy resin with an epoxide value of 0.78eq / 100g and a viscosity of 3900mPa·s.

[0085] Application Example 1

[0086] The diethyltoluenediamine epoxy resin prepared in Example 1 was added to 65g of E-51 bisphenol A epoxy resin, and then 3.25g of 4,4'-diaminodiphenylmethane was added for curing. The curing conditions were: heating from room temperature to 100°C and then keeping it for 2h, then heating to 130°C and then keeping it for 2h, then heating to 160°C and then keeping it for 2h (recorded as 100°C / 2h+130°C / 2h+160°C / 2h), aging at room temperature for 7d to obtain diethyltoluenediamine epoxy resin modified bisphenol A epoxy resin, wherein the calculation method of the amount of diethyltoluenediamine epoxy resin added was: the mass fraction of diethyltoluenediamine epoxy resin in bisphenol A epoxy resin. The performance test results are shown in Table 1.

[0087] Table 1 Performance test results of diethyltoluenediamine epoxy resin modified bisphenol A epoxy resin

[0088]

[0089] From the results in Table 1, it can be seen that the addition of diethyltoluenediamine epoxy resin can significantly improve the tensile strength (55.97-68.45MPa), elongation at break (3.54-4.92%), flexural strength (87.04-109.55MPa) and impact strength (13.61-19.2kJ / m 2 ). Among them, the tensile strength and elongation at break of the cured product of 10% diethyltoluenediamine epoxy resin are the best, and the bending strength and impact strength are also very high, and its comprehensive mechanical properties are the best.

[0090] Scanning electron microscope test: After the fracture surface of the impact samples of pure E-51 epoxy resin and modified E-51 epoxy resin with 10wt% diethyltoluenediamine epoxy resin was gold plated, the pore morphology was observed using an American Quanta 200 environmental scanning electron microscope. The results are as follows: Figure 3 shown.

[0091] Figure 3 The scanning electron microscope images of the impact fracture surfaces of pure E-51 epoxy resin and modified E-51 epoxy resin with 10 wt% diethyltoluenediamine epoxy resin added, wherein (a) is pure E-51 epoxy resin, and (b) is modified E-51 epoxy resin with 10 wt% diethyltoluenediamine epoxy resin added. Figure 3 It can be seen that the surface of the pure E-51 cured product is smooth and flat, with only a few cracks. When 10% DETGA is added, although a small part of the tough fracture characteristics such as ridges and oriented strands appear, the fracture surface of the cured product becomes smoother overall, with more smooth and regular cracks, which is a typical characteristic of rigid fracture, overcoming the disadvantages of hardness and brittleness. This is because the addition of a small amount of DETGA instead of E-51 increases the crosslinking density of the composite resin. Therefore, compared with pure E-51 resin, the rigidity of the composite resin is enhanced, and the tensile strength and bending strength are greater than those of pure E-51 resin.

[0092] The thermal stability of pure E-51 epoxy resin and modified E-51 epoxy resin with 10wt% diethyltoluenediamine epoxy resin was tested and analyzed using a TGA / DSCl / 1100SF thermogravimetric analyzer. The test parameters of the thermogravimetric analyzer were set as follows: temperature range 30-700°C, temperature rise rate 10°C / min, carrier gas nitrogen, and its flow rate 40mL / min; the results are as follows Figure 4 shown.

[0093] Figure 4The thermal weight loss curves of pure E-51 epoxy resin and modified E-51 epoxy resin with 10 wt% diethyltoluenediamine epoxy resin added, wherein (a) is pure E-51 epoxy resin, (b) is modified E-51 epoxy resin with 10 wt% diethyltoluenediamine epoxy resin added, Figure 5 It can be seen that the residue amount of 10% DETGA / E-51 solidified material at 700℃ is 14.5%, which is 1.2% higher than that of pure E-51 solidified material; and the temperature at which the maximum decomposition rate of 10% DETGA / E-51 solidified material is at 382~386℃, which is 2~4℃ higher than that of pure E-51 solidified material, and the thermal stability has been improved to a certain extent. The reason may be that the introduction of the rigid benzene ring structure not only greatly improves the mechanical properties of the material, but also significantly improves the thermal stability.

[0094] Figure 5 This is a storage stability test diagram of the diethyltoluenediamine epoxy resin obtained in Example 1. Figure 5 It can be seen that as time changes, the viscosity of the diethyltoluenediamine epoxy resin provided by the present invention tends to be stable and is not easy to cross-link.

[0095] It can be seen from the above embodiments and application examples that the diethyltoluenediamine epoxy resin provided by the present invention has a relatively high epoxy value. After being added to the E-51 resin, the toughness, rigidity and high temperature resistance of the cured product can be improved.

[0096] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A diethyltoluenediamine epoxy resin, characterized in that It has the structure shown in formula I:

2. The diethyltoluenediamine epoxy resin according to claim 1, characterized in that: The epoxy value of the diethyltoluenediamine epoxy resin is ≥0.80eq / 100g, and the viscosity is ≤4000mPa·s.

3. The method for preparing the diethyltoluenediamine epoxy resin according to claim 1 or 2, characterized in that: The following steps are involved: Diethyltoluenediamine, epichlorohydrin, a promoter and a phase transfer catalyst are mixed and subjected to a ring-opening reaction to obtain an intermediate product having a structure shown in formula II; The intermediate product is mixed with an inorganic alkali solution to carry out a ring-closing reaction to obtain the diethyltoluenediamine epoxy resin.

4. The preparation method according to claim 3, characterized in that: The promoter is an alcohol reagent; and the phase transfer catalyst is a quaternary ammonium salt.

5. The preparation method according to claim 3, characterized in that: The inorganic base in the inorganic base solution is an alkali metal hydroxide.

6. The preparation method according to claim 3, characterized in that: The molar ratio of diethyltoluenediamine to epichlorohydrin is 1:4-10; The mass of the accelerator is 1 to 40% of the mass of diethyltoluenediamine; The mass of the phase transfer catalyst is 0.05-0.5% of the total mass of diethyltoluenediamine, epichlorohydrin and the inorganic base; The molar ratio of the diethyltoluenediamine to the inorganic base in the inorganic base solution is 1:4-5.

7. The preparation method according to claim 3 or 6, characterized in that: The temperature of the ring-opening reaction is 30-130° C., and the time is 2-8 hours.

8. The preparation method according to claim 3 or 6, characterized in that: The temperature of the ring-closing reaction is 30-100° C., and the time is 0.5-5 h.

9. A modified epoxy resin, characterized in that: A modified epoxy resin using the diethyltoluenediamine epoxy resin as claimed in claim 1 or 2 or the diethyltoluenediamine epoxy resin prepared by the preparation method according to claims 3 to 8 as a modifier.

10. The modified epoxy resin according to claim 9, characterized in that: Includes the following components: Epoxy resin; Diethyltoluenediamine epoxy resin accounting for 5 to 20% by mass of the epoxy resin; A curing agent that matches the total epoxy value of the epoxy resin and the diethyltoluenediamine epoxy resin.

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