Dielectric thermal-conduction enhanced bio-based high-temperature-resistant epoxy resin, and preparation method and application thereof

Abstract

Disclosed in the present invention are a dielectricity and thermal conductivity enhanced bio-based high-temperature-resistant epoxy resin, a preparation method therefor, and an application thereof. Th

Description

5 TECHNICAL FIELD The present invention belongs to the field of polymer synthesis, and particularly relates to a dielectric thermal-conduction enhanced bio-based high-temperature-resistant epoxy resin, and a preparation method and application thereof. 10 BACKGROUND Epoxy resin polymer is usually formed by cross-linking polymerization of an epoxy resin monomer and a curing agent, and is widely used in coating adhesive and electronic and electrical industries, multi-component composite materials and 15 engineering technology research fields. However, at present, most commercial CM epoxy resins are prepared from petroleum raw materials, and a bisphenol A epoxy resin accounts for more than 90% of total epoxy resin output. Although epichlorohydrin, which is one of raw materials, may be prepared from glycerin, which is a biomass raw material, bisphenol A, which is another main raw material, 1 20 can only be produced from the petroleum raw materials at present. Petroleum is a non-renewable resource, and has been consumed in large quantities at present, causing a series of problems such as shortage of petroleum resources, soaring price of petroleum and environmental pollution, which have forced people to focus on the field of sustainable development. In addition, the bisphenol A epoxy resin 25 has high viscosity at room temperature, poor fluidity, and high requirements on a construction process, and the epoxy resin obtained by curing has poor flame retardance and electrical conductivity, so that an application of the epoxy resin in high-tech fields is limited. In 2019, the patent CN110408003A disclosed a preparation method of a 30 honokiol epoxy resin, and corresponding difunctional and tetrafunctional epoxy resins were prepared with a natural Mangnolia officinalis derivative as a raw material. The Mangnolia officinalis derivative may be used for preparing Chinese herbal medicines and cosmetics, and has been proved to be a safe and low toxic compound. The preparation of the epoxy resin from this raw material can reduce health hazards of the epoxy resin to a human body. Moreover, a preparation process of the bio-based epoxy resin is simple and efficient, and is beneficial for large-scale production. It is more noteworthy that the bio-based epoxy resin after curing has excellent thermal resistance, mechanical property and flame 5 retardance. However, there is no literature report on researches of dielectric property and thermal conductivity of related materials. In 2017, the patent CN107057289A disclosed a high-thermal-conductivity and high-temperature-resistant epoxy resin and a preparation method thereof, and a potting epoxy resin was used as a potting material and applied to high-thermal- 10 conductivity and high-temperature-resistant potting of new energy power batteries and motors, and wind power generation stators and motors. Meanwhile, there are few literature reports on bio-based epoxy resin materials with high thermal conductivity, high temperature resistance and strong electrical conductivity. Therefore, through the in-depth development of bio-based compounds, the 15 preparation of dielectric thermal-conduction enhanced high-temperature-resistant CM bio-based epoxy resin materials has a good research and application value, and is also one of frontier directions of functional transformation and application research of bio-based materials. 20 SUMMARY Object of the invention: the technical problem to be solved by the present invention is to provide a dielectric thermal-conduction enhanced bio-based high-temperature-resistant epoxy resin aiming at the defects in the prior art. The technical problem to be further solved by the present invention is to 25 provide a preparation method of the dielectric thermal-conduction enhanced biobased high-temperature-resistant epoxy resin above. The technical problem to be finally solved by the present invention is to provide an application of the dielectric thermal-conduction enhanced bio-based high-temperature-resistant epoxy resin above in a dielectric capacitor material. 30 In order to solve the first technical problem above, the present invention discloses a dielectric thermal-conduction enhanced bio-based high-temperature-resistant epoxy resin, wherein a frequency range is 0 MHz to 3 MHz, a dielectric constant remains constant at 8.2 to 10 basically. 17 07 23 Further, a change of a dielectric loss of the epoxy resin with a frequency is no higher than 0.075. Further, a thermal conductivity coefficient of the epoxy resin is no less than 0.43 W / m*K, and a specific heat capacity is no less than 2.3 J / g*K. 5 Preferably, the thermal conductivity coefficient of the epoxy resin is no less than 0.743 W / m*K, and the specific heat capacity is no less than 5.364 J / g*K. Further, an initial decomposition temperature of the epoxy resin is 405°C to 420°C, and a temperature corresponding to a maximum decomposition rate is 445°C to 455°C; and preferably, the initial decomposition temperature of the epoxy 10 resin is 410°C, and the temperature corresponding to the maximum decomposition rate is 451 °C. Further, the epoxy resin is capable of being extinguished after burning for 60 seconds, and preferably for 25 seconds. In order to solve the second technical problem above, the present invention 15 discloses a preparation method of the epoxy resin above, wherein an epoxy resin monomer used in a preparation process comprises a compound shown in formula DBDBBB: The epoxy resin monomer may be the compound shown in formula DBDBBB 20 itself, or a mixture of the compound shown in formula DBDBBB and other monomers, such as a mixture of the compound shown in formula DBDBBB and DGEBA. o o DGEBA The compound shown in formula DBDBBB is prepared by a reaction of 25 honokiol (a compound shown in formula C) and epichlorohydrin. Specifically, the reaction comprises: uniformly mixing epichlorohydrin, tetrabutylammonium bromide and 50% w / w sodium hydroxide solution at room temperature for 30 minutes, dropwise adding honokiol dissolved with 5 tetrahydrofurane, extracting the mixture with dichloromethane after complete reaction at 50°C, drying the extracted organic phase with anhydrous sodium sulfate, then concentrating the dried organic phase by rotary distillation, and separating the concentrated organic phase by a silica gel column (petroleum ether and ethyl acetate 30 / 1 to 6 / 1) to obtain the compound. 10 A weight ratio of the epichlorohydrin to the tetrabutylammonium bromide and the sodium hydroxide solution is (38 to 42): 1: (26 to 32). A mass ratio of the honokiol to the epichlorohydrin is 1: (4 to 5); and a dosage ratio of the honokiol to the tetrahydrofuran is 0.2 g / mL to 0.3 g / mL. According to the preparation method of the epoxy resin, epoxy DBDBBB and 15 an amine curing agent are subjected to a solventless curing reaction to prepare a corresponding bio-based epoxy resin polymer material; and specifically, the preparation method comprises the following steps of: (1) introducing nitrogen into the epoxy resin monomer (the compound shown in formula DBDBBB) to obtain a deoxygenated epoxy resin monomer; 20 (2) adding a curing agent into the deoxygenated epoxy resin monomer obtained in the step (1) at a certain temperature in a nitrogen atmosphere, melting the mixture at a high temperature, uniformly stirring, and pouring the mixture into a mold; and (3) curing the mold in the step (2) at a high temperature in the nitrogen 25 atmosphere, cooling the mold in the nitrogen atmosphere, and demoulding to obtain the epoxy resin. In the step (2), the curing agent is a diamine curing agent. In the step (2), the diamine curing agent is any one or a combination two of 4,4'-diaminodiphenyl sulfone (44DDS) shown in formula A and 3,3'- 30 diaminodiphenyl sulfone (33DDS) shown in formula B (1 mol of curing agent contains 4 mol of NH-): A B In the step (2), an addition amount of the curing agent is controlled, so that a molar ratio of ethylene oxide group in the epoxy resin monomer to NH- in the curing agent is 1: 0.85 to 1: 1.2. 5 In the step (2), the melting at the high temperature is carried out at a temperature of 120°C to 195°C, and preferably at a temperature of 150°C to 170°C. In the step (3), the curing at the high temperature is carried out at a temperature of 170°C to 215°C, and preferably at a temperature of 200°C to 215°C. In the step (3), the curing at the high temperature lasts for 3 hours to 10 hours, 10 and preferably for 4 hours to 6 hours. In order to solve the third technical problem above, the present invention discloses an application of the dielectric thermal-conduction enhanced bio-based CO high-temperature-resistant epoxy resin above in a dielectric capacitor material. C\J This is because the bio-based epoxy resin material prepared by the 15 DBDBBB / DDS system in the present invention not only has excellent thermal stability and flame retardance, but also has excellent dielectric property and thermal conductivity, for example, at a frequency of 1,000 Hz, dielectric parameters (9.74 and 0.026) of DBDBBB / 44DDS are similar to dielectric parameters (10 and 0.04) of a fluorine-containing polyvinylidene fluoride (PVDF) dielectric material. 20 Beneficial effects: compared with the prior art, the present invention has the following advantages: (1) According to the present invention, the bio-based raw material honokiol is prepared into a green environment-friendly non-petroleum-based epoxy resin 25 material through simple conversion, the raw material is widely available, and the obtained product has strong substitutability for a petroleum-based product and high biological safety, so that biological resources are fully and efficiently utilized and a development requirement of green chemistry is met. (2) A curing process of the epoxy resin is simple in operation and convenient 30 in process, and has no solvent pollution and a high green level. (3) According to the present invention, the polymer system composed of the raw material has certain flame retardance, without using a halogen or phosphorus flame retardant or an inorganic flame retardant, so that biological safety is high. (4) A dielectric constant (s') of the obtained epoxy resin material is greater than 5 5, a dielectric constant of a traditional resin material is 2 to 4, and a dielectric constant of this system is increased to 8.2 to 10, so that there is obvious improvement compared with the traditional polymer material. (5) In terms of thermal conductivity, low thermal conductivity of traditional polymer resin (- 0.3 W / m*K) greatly limits an application thereof in electronic 10 industry; and a thermal conductivity coefficient and a specific heat capacity of a common epoxy resin material are 0.2 W / nvK to 2.2 W / m*K and 0.8 J / g«K to 1.5 J / g*K respectively, while the epoxy resin material reported in this patent has good thermal conductivity coefficient and specific heat capacity (0.743 W / m*K and 5.364 J / g*K) at the same time, so that an application of a corresponding functional 15 electronic product can be realized. (6) The decomposition temperature of the material obtained by the present invention reaches a maximum value (410°C) in current bio-based epoxy resin, and the temperature corresponding to the maximum decomposition rate also reaches a corresponding maximum value (451 °C), so that excellent thermal stability is shown. 20 (7) The dielectric thermal-conduction enhanced high-temperature-resistant polymer material is synthesized based on the bio-based honokiol for the first time in the present invention, which may satisfy substitution of some related petroleumbased chemicals and lay a foundation for further functional research of bio-based materials. 25 BRIEF DESCRIPTION OF THE DRAWINGS The present invention is further described in detail hereinafter with reference to the drawings and specific embodiments, and the advantages of the above and / or other aspects of the present invention will be clearer. 30 FIG. 1 shows 1H-NMR of DBDBBB. FIG. 2 is an infrared spectrogram of DBDBBB / 44DDS and DBDBDBBB / 33DDS epoxy resins (Embodiments 4 and 5). FIG. 3 is a TG spectrogram of the DBDBBB / 44DDS and DBDBDBBB / 33DDS epoxy resins (Embodiments 4 and 5). FIG. 4 shows dielectric properties of the epoxy resins (Embodiments 4 and 5). FIG. 5 shows thermal conductivities of the epoxy resins at room temperature (Embodiments 4 and 5). FIG. 6 shows flame retardance experiments of the DBDBBB / 44DDS and 5 DBDBDBBB / 33DDS epoxy resins (Embodiments 4 and 5). DETAILED DESCRIPTION A detection method in the following embodiments is as follows. Thermogravimetric test parameters: test instrument: Discovery TGA-550, 10 temperature range: 40°C to 900°C, flow rate of nitrogen: 20 mL / min, and heating rate: 20 °C / min. Dielectric test parameters: test instrument: Novocontrol Concept 80, temperature: 25°C, and test frequency: 0 Hz to 3 MHz. Thermal conductivity test parameters: test instrument: NETZSCH LFA 427, 15 temperature range: 25°C, and flow rate of argon 80 mL / min. C\l Combustion experiments are carried out according to the national standard GB 2408-96. Embodiment 1 Epichlorohydrin (64.75 g), tetrabutylammonium bromide (1.61 g) and 50% 20 (w / w) sodium hydroxide solution (48 g) were successively added into a single mouth reaction bottle, uniformly mixed at room temperature for 30 minutes, and dropwise added with honokiol (13.31 g) dissolved with tetrahydrofurane (60 mL), the mixture was extracted with dichloromethane after complete reaction at 50°C, and the extracted organic phase was dried with anhydrous sodium sulfate, then 25 concentrated by rotary distillation, and separated by a silica gel column (petroleum ether and ethyl acetate 30 / 1 to 6 / 1) to obtain 15.4 g of colorless DBDBBB liquid, with a yield of 85%, and a H-nuclear magnetic resonance spectrum shown in FIG. 1. Embodiment 2 30 The epoxy resin monomer DBDBBB (3.78 g) prepared in Embodiment 1 was added into a sample bottle, and introduced with nitrogen. After an oxygen component was removed, 4,4'-diaminodiphenyl sulfone (compound A, 1.24 g) was added in a nitrogen atmosphere. Air was further removed, and the mixture was fully mixed and stirred, and heated to 165°C to melt and mix the two uniformly. The material was poured into a stainless steel mold plate at 170°C, then heated at 210°C, cured for 2 hours, and then naturally cooled in a nitrogen atmosphere to obtain a transparent epoxy resin polymer. Embodiment 3 5 The epoxy resin monomer DBDBBB (3.78 g) prepared in Embodiment 1 was added into a sample bottle, and introduced with nitrogen. After an oxygen component was removed, 3,3'-diaminodiphenyl sulfone (compound B, 1.24 g) was added in a nitrogen atmosphere. Air was further removed, and the mixture was fully mixed and stirred, and heated to 180°C to melt and mix the two uniformly. The 10 material was poured into a stainless steel mold plate at 170°C, then heated at 210°C, cured for 2 hours, and then naturally cooled in a nitrogen atmosphere to obtain a faint yellow transparent epoxy resin polymer. Embodiment 4 15 The epoxy resin monomer DBDBBB (7.56 g) prepared in Embodiment 1 was C\l added into a sample bottle, and introduced with nitrogen. After an oxygen component was removed, 4,4'-diaminodiphenyl sulfone (compound A, 2.48 g) was added in a nitrogen atmosphere. Air was further removed, and the mixture was fully mixed and stirred, and heated to 150°C to melt and mix the two uniformly. The 20 material was poured into a stainless steel mold plate at 170°C, then heated at 210°C, cured for 2 hours, and then naturally cooled in a nitrogen atmosphere to obtain a transparent epoxy resin polymer. A dielectric constant of the obtained epoxy resin polymer was 9.74, and a change of a dielectric loss with a frequency was 0.026. 25 Embodiment 5 The epoxy resin monomer DBDBBB (7.56 g) prepared in Embodiment 1 was added into a sample bottle, and introduced with nitrogen. After an oxygen component was removed, 3,3'-diaminodiphenyl sulfone (compound B, 2.48 g) was added in a nitrogen atmosphere. Air was further removed, and the mixture was 30 fully mixed and stirred, and heated to 170°C to melt and mix the two uniformly. The material was poured into a stainless steel mold plate at 170°C, then heated at 210°C, cured for 2 hours, and then naturally cooled in a nitrogen atmosphere to obtain a faint yellow transparent epoxy resin polymer. Infrared spectra of the epoxy resin polymers prepared in Embodiment 4 and Embodiment 5 are shown in FIG. 2, TG spectra of the epoxy resin polymers are shown in FIG. 3, dielectric properties of the epoxy resin polymers are shown in FIG. 4, thermal conductivities of the epoxy resin polymers are shown in FIG. 5, and 5 flame retardance experiments of the epoxy resin polymers are shown in FIG. 6. Comparative Example 1 Similar to Embodiment 4, the epoxy resin monomer was replaced by DGEBA from DBDBDBBB, melted at 180°C and then poured, and then cured at 215°C for 2 hours to obtain the epoxy resin material. A combustion experiment showed that the 10 combustion lasted for 155 seconds and then was extinguished, which showed that the corresponding DBDBBB material system had better flame retardance. A dielectric test showed that, in a range of 0 MHz to 3 MHz, a charge of a dielectric loss of the DGEBA / 44DDS polymer with a frequency (0.1 to 0.45) was great, which was obviously higher than that of the DBDBBB / DDS system (<0.075). Therefore, 15 the DGEBA / DDS system was not suitable for being used as a dielectric material due to large energy consumption and a high calorific value. In addition, a thermal conductivity coefficient and a specific heat capacity of the DGEBA / 44DDS were both small, which were 0.333 W / m*K and 1.96 J / g«K respectively, and were obviously smaller than those of the bio-based DBDBBB / DDS system. However, a 20 thermal conductivity coefficient and a specific heat capacity of a common epoxy resin material were 0.2 W / nvK to 2.2 W / nvK and 0.8 J / g*K to 1.5 J / g»K respectively. Therefore, the polymer system developed based on the bio-based DBDBBB not only had flame retardance, but also had obviously enhanced dielectric property and thermal conductivity. DGEBA The present invention provides an idea and a method for a dielectric thermalconduction enhanced bio-based high-temperature-resistant epoxy resin and a preparation method thereof, with many methods and ways to realize the technical solution specifically. Those described above are merely the preferred embodiments 30 of the present invention, and it should be pointed out that those of ordinary skills in the art may further make improvements and decorations without departing from the principle of the present invention, and these improvements and decorations should also be regarded as the scope of protection of the present invention. All the unspecified components in the embodiments can be realized by the prior art. 17 07 23

Claims

1. A dielectric thermal-conduction enhanced bio-based high-temperature-resistant epoxy resin, wherein a dielectric constant of the epoxy resin is 8.2 to 10.

2. The epoxy resin according to claim 1, wherein a thermal conductivity coefficient of the epoxy resin is no less than 0.43 W / m»K, and a specific heat capacity is no less than 2.3 J / g*K.

3. A preparation method of the epoxy resin according to claim 1 or 2, wherein an epoxy resin monomer used in a preparation process comprises a compound shown in formula DBDBBB:

4. The preparation method according to claim 3, wherein the compound shown in formula DBDBBB is prepared by a reaction of honokiol and epichlorohydrin.

5. The preparation method according to claim 3, comprising the following steps of:(1) introducing nitrogen into the epoxy resin monomer to obtain a deoxygenated epoxy resin monomer;(2) adding a curing agent into the deoxygenated epoxy resin monomer obtained in the step (1) in a nitrogen atmosphere, melting the mixture at a high temperature, uniformly stirring, and pouring the mixture into a mold; and(3) curing the mold in the step (2) at a high temperature in the nitrogen atmosphere, cooling the mold in the nitrogen atmosphere, and demoulding to obtain the epoxy resin.

6. The preparation method according to claim 5, wherein in the step (2), the curing agent is a diamine curing agent.

7. The preparation method according to claim 6, wherein in the step (2), the diamine curing agent is any one or a combination two of 4,4'-diaminodiphenyl sulfone shown in formula A and 3,3'-diaminodiphenyl sulfone shown in formula B:

8. The preparation method according to claim 6, wherein in the step (2), an addition amount of the curing agent is controlled, so that a molar ratio of ethylene oxide group in the epoxy resin monomer to NH- in the curing agent is 1: 0.85 to 1: 1.2; and the melting at the high temperature is carried out at a temperature of10 120°C to 195°C.

9. The preparation method according to claim 6, wherein in the step (3), the curing at the high temperature is carried out at a temperature of 170°C to 215°C, and lasts for 3 hours to 10 hours.1510. An application of the dielectric thermal-conduction enhanced bio-based high-temperature-resistant epoxy resin according to claim 1 or 2 in a dielectric capacitor material.

Images