A dielectric thermal conductivity enhanced bio-based high temperature resistant epoxy resin and its preparation method and application

Abstract

The present invention discloses a dielectric thermal conductivity enhanced bio-based high temperature resistant epoxy resin and a preparation method and application thereof, wherein the dielectric constant of the epoxy resin is 8.2 to 10. The method has a simple operation process and a short curing time. The obtained bio-epoxy resin polymer material has excellent performance, the dielectric constant is increased to between 8.2 and 10, and it has good thermal conductivity and heat capacity ratio (0.743 W / m·K, 5.364 J / g·K), which can meet the application of corresponding functional electronic products.

Description

Technical Field

[0001] The invention belongs to the field of polymer synthesis, and specifically relates to a dielectric thermal conductivity enhanced bio-based high temperature resistant epoxy resin and a preparation method and application thereof. Background Art

[0002] Epoxy resin polymers are usually cross-linked and polymerized by epoxy resin monomer materials and curing agents, and are widely used in the coating adhesive and electronic and electrical industries, multi-component composite materials, and engineering technology research fields. However, most of the commercial epoxy resins are currently produced from petroleum raw materials, and more than 90% of the total output of epoxy resins is bisphenol A epoxy resin. Although one of its raw materials, epichlorohydrin, can be produced from biomass raw material glycerol, another main raw material, bisphenol A, can only be produced from petroleum raw materials. Petroleum is a non-renewable resource that has been consumed in large quantities. The resulting shortage of petroleum resources, soaring oil prices, and environmental pollution have forced people to focus their research on the field of sustainable development. In addition, bisphenol A epoxy resin has high viscosity and poor fluidity at room temperature, and has high requirements for construction technology. The flame retardancy and electrical conductivity of the cured epoxy resin are poor, and its application in the field of high technology is limited.

[0003] Patent CN110408003A in 2019 discloses a method for preparing honokiol epoxy resin, and uses natural magnolia bark derivatives as raw materials to prepare corresponding difunctional and tetrafunctional epoxy resins. Magnolia bark derivatives can be used to prepare Chinese herbal medicines and cosmetics, and have been proven to be safe and low-toxic compounds. Using this as a raw material to prepare epoxy resin can reduce the health risks of epoxy resin to the human body. Moreover, the preparation process of the bio-based epoxy resin is simple and efficient, which is conducive to large-scale production. More importantly, the bio-based epoxy resin has excellent heat resistance, mechanical properties and flame retardant properties after curing. However, there is no literature report on the research of dielectric properties and thermal conductivity of related materials.

[0004] Patent CN107057289A in 2017 discloses a high thermal conductivity and high temperature resistant epoxy resin and its preparation method. The potting epoxy resin is used as a potting material and is applied to high conductivity and high temperature resistant potting of new energy power batteries and motors, wind power generation stators and motors. 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 preparation of dielectric thermal conductivity enhanced high temperature resistant bio-based epoxy resin materials has good research and application value, and is also one of the frontier directions of research on the functional transformation and application of bio-based materials. Summary of the invention

[0005] Purpose of the invention: The technical problem to be solved by the present invention is to provide a dielectric thermally conductive enhanced bio-based high temperature resistant epoxy resin in view of the deficiencies in the prior art.

[0006] The technical problem that the present invention also solves is to provide the above-mentioned dielectric thermal conductivity enhanced bio-based high temperature resistant epoxy resin and a preparation method thereof.

[0007] The final technical problem to be solved by the present invention is to provide the application of the above-mentioned dielectric thermal conductivity enhanced bio-based high temperature resistant epoxy resin in dielectric capacitor materials.

[0008] In order to solve the first technical problem mentioned above, the present invention discloses a dielectric thermal conductivity enhanced bio-based high temperature resistant epoxy resin, in which the dielectric constant is basically kept constant at 8.2 to 10 in the frequency range of 0-3 MHz.

[0009] Furthermore, the dielectric loss of the epoxy resin varies with frequency and is no more than 0.075.

[0010] Furthermore, the thermal conductivity of the epoxy resin is not less than 0.43 W / m·K, and the heat capacity ratio is not less than 2.3 J / g·K

[0011] Preferably, the thermal conductivity of the epoxy resin is not less than 0.743 W / m·K, and the heat capacity ratio is not less than 5.364 J / g·K.

[0012] Furthermore, the initial decomposition temperature of the epoxy resin is 405-420°C, and the temperature corresponding to the maximum decomposition rate is 445-455°C; preferably, the initial decomposition temperature of the epoxy resin is 410°C, and the temperature corresponding to the maximum decomposition rate is 451°C.

[0013] Furthermore, the epoxy resin can be extinguished after burning for 60 seconds, more preferably 25 seconds.

[0014] In order to solve the second technical problem, the present invention discloses a method for preparing the epoxy resin. The epoxy resin monomer used in the preparation process includes a compound represented by the formula DBDBBB;

[0015]

[0016] That is, the epoxy resin monomer may be the compound represented by the formula DBDBBB itself, or may be a mixture of the compound represented by the formula DBDBBB and other monomers, such as a mixture of the compound represented by the formula DBDBBB and DGEBA.

[0017]

[0018] Wherein, the compound represented by formula DBDBBB is prepared by reacting honokiol (the compound represented by formula C) with epichlorohydrin;

[0019]

[0020] Specifically, the reaction is to mix epichlorohydrin, tetrabutylammonium bromide and 50% w / w sodium hydroxide aqueous solution at room temperature for 30 minutes, then add honokiol dissolved in tetrahydrofuran dropwise, and after the reaction is complete at 50°C, extract with dichloromethane, dry the organic phase obtained by extraction with anhydrous sodium sulfate, concentrate it with rotary evaporation, and separate it with a silica gel column (petroleum ether and ethyl acetate 30 / 1-6 / 1) to obtain the product.

[0021] Wherein, the weight ratio of epichlorohydrin, tetrabutylammonium bromide and sodium hydroxide aqueous solution is (38-42):1:(26-32).

[0022] The mass ratio of honokiol to epichlorohydrin is 1:(4-5); and the dosage ratio of honokiol to tetrahydrofuran is 0.2-0.3 g / mL.

[0023] The preparation method of the epoxy resin comprises the following steps: preparing the corresponding bio-based epoxy resin polymer material by solvent-free curing reaction of epoxy DBDBBB and an amine curing agent; specifically, the method comprises the following steps:

[0024] (1) introducing nitrogen into an epoxy resin monomer (a compound represented by the formula DBDBBB) to obtain a deoxygenated epoxy resin monomer;

[0025] (2) under nitrogen atmosphere, at a certain temperature, adding a curing agent to the deoxygenated epoxy resin monomer obtained in step (1), melting at high temperature, stirring evenly, and pouring into a mold;

[0026] (3) The mold in step (2) is cured at high temperature under a nitrogen atmosphere, cooled under a nitrogen atmosphere, and demolded to obtain the product.

[0027] In step (2), the curing agent is a diamine curing agent.

[0028] In step (2), the diamine curing agent is any one or a combination of 4,4′-diaminodiphenyl sulfone (44DDS) shown in formula A and 3,3′-diaminodiphenyl sulfone (33DDS) shown in formula B (1 mol of the curing agent contains 4 mol NH-);

[0029]

[0030] In step (2), the amount of curing agent added is controlled so that the molar ratio of the ethylene oxide group in the epoxy resin monomer to the NH- in the curing agent is 1:0.85 to 1:1.2.

[0031] In step (2), the high temperature melting temperature is 120-195°C, preferably 150-170°C.

[0032] In step (3), the high temperature curing is performed at a temperature of 170 to 215°C, preferably 200 to 215°C.

[0033] In step (3), the high temperature curing has a curing time of 3 to 10 hours, preferably 4 to 6 hours.

[0034] In order to solve the third technical problem mentioned above, the present invention discloses the application of the above dielectric thermal conductivity enhanced bio-based high temperature resistant epoxy resin in dielectric capacitor materials.

[0035] This is because the bio-based epoxy resin material prepared by the DBDBBB / DDS system in the present invention not only has excellent thermal stability and flame retardancy, but also has relatively excellent dielectric properties and thermal conductivity. For example, at a frequency of 1000 Hz, the dielectric parameters of DBDBBB / 44DDS (9.74, 0.026) are similar to those of fluorinated polyvinylidene fluoride dielectric material (PVDF) (10, 0.04), showing good substitutability.

[0036] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0037] (1) The bio-based raw material and magnolia bark phenol of the present invention are prepared by simple conversion to obtain a green and environmentally friendly non-petroleum-based epoxy resin material. The raw material has a wide source, and the obtained product is highly substitutable for petroleum-based products and has high biosafety, which fully realizes the efficient utilization of biological resources and meets the development requirements of green chemistry.

[0038] (2) The epoxy resin curing process is simple to operate, convenient in process, free of solvent pollution, and has a high level of greenness.

[0039] (3) The polymer system formed by the raw materials of the present invention has certain flame retardancy, does not use halogen or phosphorus flame retardants or inorganic flame retardants, and has high biological safety.

[0040] (4) The dielectric constant (ε′) of the obtained epoxy resin material is greater than 5. The dielectric constant of traditional resin materials is between 2 and 4. The dielectric constant of this system is increased to between 8.2 and 10, which is a significant improvement compared with traditional polymer materials.

[0041] (5) In terms of thermal conductivity, the low thermal conductivity of traditional polymer resins (~0.3W / m·K) has largely limited their application in the electronics industry. The thermal conductivity and specific heat capacity of common epoxy resin materials are 0.2-2.2W / m·K and 0.8-1.5J / g·K, respectively. The epoxy resin material reported in this patent has both good thermal conductivity and heat capacity ratio (0.743W / m·K, 5.364J / g·K), which can meet the application requirements of corresponding functional electronic products.

[0042] (6) The decomposition temperature of the material obtained by the present invention is the highest among the current bio-based epoxy resins (410°C), and the temperature corresponding to the maximum decomposition rate also reaches the corresponding maximum value (451°C), showing excellent thermal stability.

[0043] (7) The present invention is the first to synthesize a high-temperature resistant polymer material with enhanced dielectric thermal conductivity based on bio-based magnolia phenol, which can meet the requirements of replacing some related petroleum-based chemicals and also lay the foundation for further research on the functionalization of bio-based materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0045] Figure 1 For DBDBBB 1 H-NMR.

[0046] Figure 2 The infrared spectra of DBDBBB / 44DDS and DBDBBB / 33DDS epoxy resins (Examples 4 and 5).

[0047] Figure 3 TG spectra of DBDBBB / 44DDS and DBDBBB / 33DDS epoxy resins (Examples 4, 5).

[0048] Figure 4 is the dielectric property of epoxy resin (Examples 4, 5).

[0049] Figure 5 is the thermal conductivity of epoxy resin at room temperature (Examples 4, 5).

[0050] Figure 6 This is the flame retardancy test of DBDBB / 44DDS and DBDBB / 33DDS epoxy resins (Examples 4 and 5). DETAILED DESCRIPTION

[0051] The detection methods in the following embodiments are as follows:

[0052] Thermogravimetric test parameters: test instrument Discovery TGA-550, temperature range 40-900°C, nitrogen flow rate 20mL / min, heating rate 20°C / min.

[0053] Dielectric test parameters: Test instrument Novocontrol Concept 80, 25°C, test frequency 0Hz-3MHz. Thermal conductivity test: Test instrument NETZSCH LFA 427, 25°C, argon flow rate 80mL / min.

[0054] The combustion experiment is carried out in accordance with the national standard GB 2408-96.

[0055] Example 1

[0056] Epichlorohydrin (64.75 g), tetrabutylammonium bromide (1.61 g) and 48 g of 50% (w / w) sodium hydroxide aqueous solution were added successively to a single-mouth reaction bottle. After being mixed evenly at room temperature for half an hour, honokiol (13.31 g) dissolved in tetrahydrofuran (60 mL) was added dropwise. After the reaction was complete at 50° C., dichloromethane was extracted, and the organic phase obtained by the extraction was dried over anhydrous sodium sulfate, concentrated by rotary evaporation, and separated by a silica gel column (petroleum ether and ethyl acetate 30 / 1-6 / 1) to obtain 15.4 g of colorless DBDBBB liquid with a yield of 85%. Its hydrogen spectrum nuclear magnetic resonance is as follows Figure 1 shown.

[0057] Example 2

[0058] The epoxy resin monomer DBDBBB (3.78 g) prepared in Example 1 was weighed into a sample bottle, and nitrogen was introduced to remove the oxygen component. Then, 4,4′-diaminodiphenyl sulfone (Compound A, 1.24 g) was added under nitrogen atmosphere, and air was further removed. The mixture was fully mixed and stirred, and the temperature was raised to 165°C to melt and mix the two. The material was poured into a 170°C stainless steel mold plate, and then heated in an atmosphere of 210°C. After curing for 2 hours, it was naturally cooled under nitrogen atmosphere to obtain a transparent epoxy resin polymer.

[0059] Example 3

[0060] The epoxy resin monomer DBDBBB (3.78 g) prepared in Example 1 was weighed into a sample bottle, and nitrogen was introduced to remove the oxygen component. Then, 3,3′-diaminodiphenyl sulfone (Compound B, 1.24 g) was added under a nitrogen atmosphere, and the air was further removed. The mixture was fully mixed and stirred, and the temperature was raised to 180°C to melt and mix the two. The material was poured into a 170°C stainless steel abrasive plate, and then heated in an atmosphere of 210°C. After curing for 2 hours, it was naturally cooled under a nitrogen atmosphere to obtain a light yellow transparent epoxy resin polymer.

[0061] Example 4

[0062] The epoxy resin monomer DBDBBB (7.56 g) prepared in Example 1 was weighed into a sample bottle, and nitrogen was introduced to remove the oxygen component. Then, 4,4′-diaminodiphenyl sulfone (Compound A, 2.48 g) was added under nitrogen atmosphere, and the air was further removed. The mixture was fully mixed and stirred, and the temperature was raised to 150°C to melt and mix the two. The material was poured into a 170°C stainless steel mold plate, and then heated in an atmosphere of 210°C. After curing for 2 hours, it was naturally cooled in a nitrogen atmosphere to obtain a transparent epoxy resin polymer. The dielectric constant of the obtained epoxy resin polymer was 9.74, and the change of dielectric loss with frequency was 0.026.

[0063] Example 5

[0064] The epoxy resin monomer DBDBBB (7.56 g) prepared in Example 1 was weighed into a sample bottle, and nitrogen was introduced to remove the oxygen component. Then, 3,3′-diaminodiphenyl sulfone (Compound B, 2.48 g) was added under a nitrogen atmosphere, and the air was further removed. The mixture was fully mixed and stirred, and the temperature was raised to 170°C to melt and mix the two. The material was poured into a 170°C stainless steel abrasive plate, and then heated in an atmosphere of 210°C. After curing for 2 hours, it was naturally cooled under a nitrogen atmosphere to obtain a light yellow transparent epoxy resin polymer.

[0065] Infrared spectra of epoxy resin polymers prepared in Example 4 and Example 5 Figure 2 As shown, TG Figure 3 The dielectric properties are shown in Figure 4 As shown, the thermal conductivity is Figure 5 As shown, the flame retardant test Figure 6 shown.

[0066] Comparative Example 1

[0067] As in Example 4, the epoxy resin monomer was replaced from DBDBBB to DGEBA, and the epoxy resin material was melted at 180°C and then cast, and then cured at 215°C for 2h. The combustion test found that the combustion continued for 155s before it was extinguished, indicating that the corresponding DBDBBB material system has better flame retardant properties. Dielectric tests found that in the range of 0-3MHz, the dielectric loss of DGEBA / 44DDS polymer varies greatly with frequency (0.1-0.45), which is significantly higher than that of DBDBBB / DDS system (<0.075). Therefore, the DGEBA / DDS system has a large energy consumption in energy storage and a large heat generation, and is not suitable for use as a dielectric material. In addition, the thermal conductivity and specific heat capacity of DGEBA / 44DDS are both small, 0.333W / m·K and 1.96J / g·K", respectively, which are significantly smaller than those of the bio-based DBDBBB / DDS system. The thermal conductivity and specific heat capacity of common epoxy resin materials are 0.2-2.2W / m·K and 0.8-1.5J / g·K, respectively. Therefore, the polymer system developed based on bio-based DBDBBB is not only flame retardant, but also has significantly enhanced dielectric and thermal conductivity properties.

[0068]

[0069] The present invention provides a dielectric thermal conductivity enhanced bio-based high temperature resistant epoxy resin and a method for preparing the same. There are many methods and approaches to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. A method for preparing an epoxy resin, characterized in that: The steps include: (1) introducing nitrogen into the epoxy resin monomer to obtain a deoxygenated epoxy resin monomer; (2) under a nitrogen atmosphere, adding a curing agent to the deoxygenated epoxy resin monomer obtained in step (1), melting at high temperature, stirring evenly, and pouring into a mold; (3) curing the mold in step (2) at high temperature under a nitrogen atmosphere, cooling under a nitrogen atmosphere, and demolding to obtain the product; In step (1), the epoxy resin monomer comprises a compound represented by the formula DBDBBB; The preparation method of the compound represented by the formula DBDBBB is as follows: after mixing epichlorohydrin, tetrabutylammonium bromide and sodium hydroxide aqueous solution at room temperature for half an hour, adding honokiol dissolved in tetrahydrofuran, reacting completely at 50°C, extracting, drying the organic phase obtained by extraction, concentrating, and column separation to obtain the compound; wherein the mass ratio of epichlorohydrin, tetrabutylammonium bromide, sodium hydroxide, and honokiol is 64.75:1.61:24:13.31; In step (2), the amount of curing agent added is controlled so that the molar ratio of the oxirane group in the epoxy resin monomer to the NH- in the curing agent is 1:0.85 to 1:1.2; In step (3), the high temperature curing temperature is 170-215°C; In step (2), the curing agent is any one or a combination of 4,4'-diaminodiphenyl sulfone as shown in formula A and 3,3'-diaminodiphenyl sulfone as shown in formula B; In step (2), the high temperature melting temperature is 120-195°C.

2. The preparation method according to claim 1, characterized in that: In step (3), the high temperature curing has a curing time of 3 to 10 hours.

3. The dielectric thermal conductivity enhanced bio-based high temperature resistant epoxy resin prepared by the method of claim 1 or 2, characterized in that: The dielectric constant of the epoxy resin is 8.2-10.

4. The epoxy resin according to claim 3, characterized in that: The thermal conductivity of the epoxy resin is not less than 0.43 W / m·K, and the heat capacity ratio is not less than 2.3 J / g·K.

5. Use of the dielectric thermal conductivity enhanced bio-based high temperature resistant epoxy resin according to claim 3 in dielectric capacitor materials.

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