Preparation method of low-temperature tough epoxy resin containing polycarbonate intermediate
By synthesizing covalent bonding of low molecular weight polycarbonate intermediates and epoxy resins, the toughness problem of epoxy resin in high and low temperature environments is solved, and an epoxy resin with both high and low temperature mechanical properties and good processability is achieved. in the spacecraft structure.
Patent Information
- Application Number
- CN202411383111.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-30
- Publication Date
- 2024-12-27
AI Technical Summary
Existing epoxy resins are prone to cracking and debonding in alternating environments of high and low temperatures, making it difficult to take into account both high-temperature strength and low-temperature toughness, and conventional toughening methods are difficult to ensure the processability of the resin and the performance requirements of the composite material.
By synthesizing covalent bonds between low molecular weight polycarbonate intermediates (PC-O) and epoxy resins, nitrogen, ethanol and protonated solvents are used to regulate the reactions to form an epoxy resin with significant low-temperature secondary relaxation ability (EP) -PC) to improve its glass transition temperature and mechanical properties.
The high and low temperature mechanical properties of epoxy resin are achieved, which significantly improves its low temperature toughness and processability, ensures excellent mechanical properties at -50℃, room temperature and 100℃, and is suitable for spacecraft structural composite materials.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of chemical materials and relates to a method for preparing a low-temperature tough epoxy resin containing a polycarbonate intermediate and capable of withstanding high and low temperatures. Background Art
[0002] Epoxy resin has good mechanical properties, chemical stability and electrical insulation properties, and is a very representative composite matrix resin. In the field of aerospace, fiber-reinforced epoxy resin-based composites have the advantages of low density, high specific strength, high modulus and good processability, and have been widely used in aerospace, ships, oceans and polar engineering. The continuous upgrading of aerospace engines and aircraft has put forward higher requirements on the performance of corresponding epoxy resin-based composite materials. For example, the temperature on the surface of the moon can reach up to 150℃ and down to -180℃; the surface temperature of Mars is about -34℃ to -80℃, and the temperature of the universe is even close to absolute zero. Secondly, the cryogenic fuels required for high-efficiency thrusters, such as liquid hydrogen and liquid oxygen tanks, face ultra-low temperature environments such as -253℃ and -183℃. In addition, aerospace engines and aircraft will experience high temperature environments during ignition and passing through the atmosphere. Alternating high and low temperatures and extreme low temperature conditions far exceed the operating temperature range of conventional epoxy resin-based composite materials, resulting in conventional epoxy resins being easily cracked, debonded and failing under low temperatures and alternating high and low temperature conditions when used to manufacture structural components such as aerospace vehicles, leading to significant losses.
[0003] Improving the toughness of epoxy resin, especially its low-temperature toughness, has always been the focus of researchers in this field. So far, researchers at home and abroad have developed a variety of methods for toughening epoxy resin, which can be summarized as follows: ① Compounding low glass transition temperature polymers such as rubber and polysiloxane with epoxy resin; ② Introducing thermoplastic polymers with flexible segments such as polyethersulfone, polyurethane, and hyperbranched polymers into epoxy resin; ③ Designing the molecular structure of epoxy resin or curing agent to introduce flexible segments into the cross-linked network of epoxy resin; ④ Adding surface-modified inorganic nanoparticles. Although these methods can improve the toughness of epoxy resin to a certain extent, composite rubber and low glass transition temperature polymers will sacrifice the modulus of the resin, making it difficult to take into account the high temperature strength and low temperature toughness of the resin; adding toughening methods such as thermoplastic polymers and nanoparticles cannot ensure the good processability of the resin prepreg required for winding molding. Therefore, it is urgent to develop an epoxy resin system that can take into account the high and low temperature performance of epoxy resin and is suitable for the fiber cloth prepreg molding process.
[0004] Polycarbonate is a kind of thermoplastic with excellent mechanical properties. gAs high as 150°C, it can also show significant secondary relaxation at -100°C. Its good high temperature strength and low temperature toughness provide a reference for obtaining epoxy resins that can withstand high and low temperatures. However, the PC molecular chain segments are rigid and have strong intermolecular forces. Directly blending PC with epoxy resins is very easy to separate into phases; combining PC and epoxy compounds through chemical bonds will greatly increase the viscosity of the resin and deteriorate its solubility, making it difficult to apply it to the dipping process. If a low molecular weight PC intermediate is used to synthesize epoxy resins, it is expected to overcome the shortcomings of direct PC modification and fully reflect the advantages of PC in epoxy resins. The patent (CN 114044880B) reports the work of preparing polycarbonate epoxy resins by reacting polycarbonate diols (PH-90) with epichlorohydrin, which is used to prepare solvent-free anti-corrosion coatings. The resulting coating has the advantages of high hardness, water resistance and wear resistance. The invention technology uses sodium hydroxide to catalyze the reaction of PH-90 and epichlorohydrin. However, in actual applications, in a system containing strong alkali, the ester bonds in PC are easily hydrolyzed, making it difficult to ensure that the final product contains sufficiently long PC segments, and it is impossible to effectively exhibit low-temperature secondary relaxation ability. Summary of the invention
[0005] The purpose of the present invention is to provide a kind of high-temperature mechanical properties with good high and low temperature mechanical properties, while taking into account the high T g The invention discloses a method for preparing a low-temperature tough epoxy resin containing a polycarbonate intermediate and having enhanced low-temperature toughness under the conditions of good high-temperature mechanical properties.
[0006] To achieve the above object, the preparation method adopted by the present invention is as follows:
[0007] 1) Synthesis of low molecular weight PC-O
[0008] 1-1) 100 parts by mass of bisphenol A and 0.5-1.2 parts of catalyst A are added to a tubular reactor, heated until the bisphenol A is melted, nitrogen is introduced under mechanical stirring, a water separator is installed, and the temperature is raised to 180-185° C.;
[0009] 1-2) adding 100 to 300 parts of dimethyl carbonate under stirring, and keeping the temperature to react until no bubbles appear on the liquid surface of the material in the tubular reactor;
[0010] 1-3) centrifuging the reaction product to remove the catalyst A therein, and vacuum drying;
[0011] 1-4) adding ethanol to the dried product at a mass ratio of 1:3, stirring and filtering to remove extremely low molecular weight components in the product, and drying the filter cake to obtain low molecular weight PC-O;
[0012] 2) Epoxidation modification of PC oligomers
[0013] 2-1) 100 parts by mass of an epoxy compound containing no alcoholic hydroxyl group are added to a four-necked flask, nitrogen is introduced under stirring, and the temperature is raised to 60° C.;
[0014] 2-2) 20 to 35 parts of low molecular weight PC-O are dissolved in 70 to 120 parts of THF, and then 1 to 6 parts of catalyst B and 1 to 6 parts of DMF are added thereto to obtain a mixed solution;
[0015] 2-3) heating the four-necked flask to 78-82° C. and adding the mixed solution to the epoxy compound containing no alcoholic hydroxyl group by a peristaltic pump under stirring;
[0016] 2-4) After the addition is completed, the reaction is continued at the temperature for 2 hours, the system is heated to 90° C., the solvent is removed by vacuum distillation, and the obtained resin is transferred to a vacuum oven for drying to obtain an epoxy resin containing a PC segment structure, which is recorded as an epoxidized EP-PC resin of an oligomer;
[0017] 3) EP-PC curing and casting preparation
[0018] Take 100 parts of oligomer epoxidized EP-PC resin by mass and heat it to 50-75°C, add 25-35 parts of curing agent thereto, stir evenly, remove bubbles in vacuum and then pour, and then cure according to the temperature program of 80°C / 1h+120°C / 1h+170°C / 1.5h to obtain a low-temperature tough epoxy resin containing a polycarbonate intermediate with good high and low temperature resistance.
[0019] The catalyst A is one of calcium acetylacetonate, zinc acetylacetonate or zirconium acetylacetonate or a mixture of any proportions thereof.
[0020] The dimethyl carbonate is added below the raw material liquid level of the tubular reactor by pumping.
[0021] The molecular weight M of the low molecular weight PC-O is n =1700~2000.
[0022] The epoxy compound not containing alcoholic hydroxyl group is one of ethylene glycol glycidyl ether, bisphenol A glycidyl ether, TDE-85 epoxy resin or AG-80 epoxy resin, or a mixture of any proportion of the two or more thereof.
[0023] The catalyst B is one or a mixture of any proportion of boron trifluoride etherate, DMP-30 and dimethylimidazole.
[0024] The above 2-4) is dried in a vacuum oven at 70° C. and a vacuum degree of -0.095 MPa to constant weight.
[0025] The curing agent is one of diaminodiphenylmethane (DDM), diaminodiphenyl sulfone (DDS), polyetheramine D230, meta-phenylenediamine, diethyltoluenediamine, or a mixture of any proportions thereof.
[0026] The present invention successfully introduces PC segments with suitable chain lengths into traditional epoxy resins, and can retain the characteristic structures of PC and epoxy resins respectively, and can effectively combine PC intermediates and epoxy groups to obtain modified epoxy resins (denoted as EP-PC) with moderate viscosity and good reactivity. After curing, EP-PC resins show outstanding low-temperature secondary relaxation properties and high glass transition temperatures, and have good high and low temperature mechanical properties. This is a new approach to bulk toughening of typical thermosetting resins represented by epoxy resins, while taking into account the high T g The low-temperature toughness is enhanced under the conditions of good high-temperature mechanical properties to prepare epoxy resin-based composite materials that can withstand low temperatures and alternating high and low temperatures.
[0027] The technical difficulties overcome by the present invention include: ① synthesizing PC-O with a moderate molecular weight, and ② controlling the appropriate degree of reaction between PC-O and epoxy resin. In the first step of the reaction, due to the existence of an equilibrium in the transesterification reaction, the byproduct methanol needs to be removed in time to shift the equilibrium to the positive direction. However, the temperature of the transesterification reaction is far higher than the boiling point of DMC. If traditional measures such as heating and vacuuming are used to remove methanol, DMC will inevitably leave the reaction system before it is fully reacted, resulting in a low yield and molecular weight of the expected product. The raw material BPA and catalyst A form a sufficiently high liquid level, and DMC is pumped into the bottom of the liquid level. In the process of DMC diffusing to the liquid surface, there is enough time to contact BPA and participate in the reaction. The use of this method can significantly increase the yield to more than 70%. In the second step, if the hydroxyl groups in PC-O do not react completely with the epoxy groups, the resin system will be separated due to the strong rigidity of the PC-O segments; and once the phenolic hydroxyl groups in PC-O react with the epoxy groups, alcoholic hydroxyl groups are generated, which will easily consume the epoxy groups in the presence of Lewis acid catalysts. Excessive consumption of epoxy groups will lead to a decrease in the functionality of the resin, making it difficult to form a complete cross-linked structure. Therefore, the present invention introduces a small amount of protonated solvent DMF to balance the catalytic properties of boron trifluoride ether, and strictly controls the feed rate, reaction time and reaction temperature to regulate the ratio of the reaction materials, so that the PC-O segments are effectively combined with the epoxy compound (the resulting resin is uniform and transparent), and retains enough epoxy groups (the epoxy equivalent of the resin is about 0.22 to 0.24 mol / g).
[0028] Compared with the prior art, the present invention has the following beneficial technologies:
[0029] 1) PC segments are effectively introduced into epoxy resin molecules through covalent bonds, thereby obtaining a cross-linked epoxy resin with significant low-temperature secondary relaxation ability;
[0030] 2) The rigid structure and secondary relaxation units of the PC chain segments are synergistically utilized, taking into account the good low-temperature toughness and high glass transition temperature of the epoxy resin, to obtain a composite matrix resin that can withstand high and low temperatures.
[0031] 3) Compared with conventional methods such as nanoparticle modification and thermoplastic resin modification, the resin obtained by the present invention has good processability and can be conveniently used for molding and casting.
[0032] In short, the present invention introduces a PC-like low molecular weight component to give the epoxy resin outstanding low-temperature secondary relaxation properties, improve the low-temperature toughness of the resin while ensuring its high glass transition temperature. The resulting EP-PC epoxy resin has good processability and can show excellent mechanical properties at -50°C, room temperature and 100°C after curing. In particular, the elongation at break at low temperatures is significantly better than commercially available resins. The present invention develops a universal new approach to toughening and modifying epoxy resins, and the resulting high and low temperature resistant epoxy resin is expected to be used as a matrix resin for aerospace vehicle structural composite materials. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Figure 1 (a) and (b) are the FTIR spectra of EP-PC obtained in Example 3 and Example 6 of the present invention, respectively.
[0034] Table 1 shows the molecular weight information of the EP-PC resin obtained in the present invention. Thanks to the low molecular weight PC-O, the average molecular weight of the obtained EP-PC is also low, ensuring good processability of the resin.
[0035] Figure 2 The DSC curves of the EP-PC resins obtained in Examples 1, 2 and 7 of the present invention are shown.
[0036] Figure 3 : (a), (c) and (e) are stress-strain curves of commercially available TDE-85 epoxy resin after curing at -50°C, room temperature and 100°C respectively; (b), (d) and (f) are stress-strain curves of the EP-PC resin cured product prepared in Example 6 of the present invention at -50°C, room temperature and 100°C respectively.
[0037] Figure 4 The tan δ curves of the EP-PC resin cured sample obtained in the present invention, the commercially available TDE-85 resin cured sample and PC (1 Hz, 3°C / min) are plotted against temperature. DETAILED DESCRIPTION
[0038] The implementation of the technical solution of the present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.
[0039] Embodiment 1:
[0040] 1) Synthesis of low molecular weight PC-O
[0041] 1-1) 100 parts by mass of bisphenol A and 0.5 parts of catalyst calcium acetylacetonate are added to a tubular reactor, heated until the bisphenol A is melted, nitrogen is introduced under mechanical stirring, a water separator is installed, and the temperature is raised to 180° C.;
[0042] 1-2) adding 120 parts of dimethyl carbonate to the tubular reactor below the raw material liquid level by pumping under stirring, and keeping the temperature to react until no bubbles appear on the material liquid level in the tubular reactor;
[0043] 1-3) centrifuging the reaction product at 10000 rpm to remove the catalyst A therein, and vacuum drying;
[0044] 1-4) adding ethanol to the dried product at a mass ratio of 1:3, stirring and filtering to remove extremely low molecular weight components in the product, and drying the filter cake to obtain low molecular weight PC-O;
[0045] 2) Epoxidation modification of PC oligomers
[0046] 2-1) 100 parts by mass of TDE-85 epoxy resin, an epoxy compound not containing alcoholic hydroxyl groups, were added to a four-necked flask, nitrogen was introduced, and the temperature was raised to 60° C.;
[0047] 2-2) 25 parts of low molecular weight PC-O were dissolved in 70 parts of THF, and 4 parts of catalyst boron trifluoride ether and 5 parts of DMF were added thereto to obtain a mixed solution;
[0048] 2-3) heating the four-necked flask to 80° C. and adding the mixed solution into the epoxy compound containing no alcoholic hydroxyl group by a peristaltic pump under stirring;
[0049] 2-4) After the addition is completed, the reaction is continued at the temperature for 2 hours, the system is heated to 90°C, the solvent is removed by vacuum distillation, and the obtained resin is transferred to a vacuum oven at 70°C and a vacuum degree of -0.095 MPa to dry to constant weight to obtain an epoxy resin containing a PC segment structure, which is recorded as an epoxidized EP-PC resin of oligomer;
[0050] 3) EP-PC curing and casting preparation
[0051] 100 parts by mass of the epoxidized EP-PC resin of the oligomer are heated to 60°C, 25 parts of the curing agent diaminodiphenylmethane (DDM) are added thereto, stirred evenly, and poured after vacuum removal of bubbles, and then cured according to the temperature program of 80°C / 1h+120°C / 1h+170°C / 1.5h to obtain a low-temperature tough epoxy resin containing a polycarbonate intermediate with good high and low temperature resistance.
[0052] Embodiment 2:
[0053] 1) Synthesis of low molecular weight PC-O
[0054] 1-1) 100 parts by mass of bisphenol A and 0.7 parts by mass of catalyst calcium acetylacetonate are added to a tubular reactor, heated until the bisphenol A is melted, nitrogen is introduced under mechanical stirring, a water separator is installed, and the temperature is raised to 180° C.;
[0055] 1-2) adding 110 parts of dimethyl carbonate to the tubular reactor below the raw material liquid level by pumping under stirring, and keeping the temperature to react until no bubbles appear on the material liquid level in the tubular reactor;
[0056] 1-3) centrifuging the reaction product at 10000 rpm to remove the catalyst A therein, and vacuum drying;
[0057] 1-4) adding ethanol to the dried product at a mass ratio of 1:3, stirring and filtering to remove extremely low molecular weight components in the product, and drying the filter cake to obtain low molecular weight PC-O;
[0058] 2) Epoxidation modification of PC oligomers
[0059] 2-1) 100 parts by mass of ethylene glycol glycidyl ether of an epoxy compound not containing alcoholic hydroxyl groups were added to a four-necked flask, nitrogen was introduced under stirring, and the temperature was raised to 60° C.;
[0060] 2-2) 20 parts of low molecular weight PC-O were dissolved in 70 parts of THF, and then 1 part of catalyst boron trifluoride ether and 2 parts of DMF were added thereto to obtain a mixed solution;
[0061] 2-3) heating the four-necked flask to 78° C. and adding the mixed solution to the epoxy compound containing no alcoholic hydroxyl group by a peristaltic pump under stirring;
[0062] 2-4) After the addition is completed, the reaction is continued at the temperature for 2 hours, the system is heated to 90°C, the solvent is removed by vacuum distillation, and the obtained resin is transferred to a vacuum oven at 70°C and a vacuum degree of -0.095 MPa to dry to constant weight to obtain an epoxy resin containing a PC segment structure, which is recorded as an epoxidized EP-PC resin of oligomer;
[0063] 3) EP-PC curing and casting preparation
[0064] 100 parts by mass of the epoxidized EP-PC resin of the oligomer are heated to 50°C, 23 parts of the curing agent diaminodiphenylmethane (DDM) and 2 parts of diethyltoluenediamine are added thereto, stirred evenly, and poured after vacuum removal of bubbles, and then cured according to the temperature program of 80°C / 1h+120°C / 1h+170°C / 1.5h to obtain a low-temperature tough epoxy resin containing a polycarbonate intermediate with good high and low temperature resistance.
[0065] Embodiment 3:
[0066] 1) Synthesis of low molecular weight PC-O
[0067] 1-1) 100 parts by mass of bisphenol A and 0.9 parts by mass of catalyst calcium acetylacetonate were added to a tubular reactor, heated until the bisphenol A was melted, nitrogen was introduced under mechanical stirring, a water separator was installed, and the temperature was raised to 183° C.;
[0068] 1-2) adding 150 parts of dimethyl carbonate to the tubular reactor below the raw material liquid level by pumping under stirring, and keeping the temperature to react until no bubbles appear on the material liquid level in the tubular reactor;
[0069] 1-3) centrifuging the reaction product at 10000 rpm to remove the catalyst A therein, and vacuum drying;
[0070] 1-4) adding ethanol to the dried product at a mass ratio of 1:3, stirring and filtering to remove extremely low molecular weight components in the product, and drying the filter cake to obtain low molecular weight PC-O;
[0071] 2) Epoxidation modification of PC oligomers
[0072] 2-1) 100 parts by mass of bisphenol A glycidyl ether, an epoxy compound not containing alcoholic hydroxyl groups, was added to a four-necked flask, nitrogen was introduced, and the temperature was raised to 60° C.;
[0073] 2-2) 30 parts of low molecular weight PC-O were dissolved in 90 parts of THF, and then 2 parts of catalyst DMP-30 and 1 part of DMF were added thereto to obtain a mixed solution;
[0074] 2-3) heating the four-necked flask to 78° C. and adding the mixed solution to the epoxy compound containing no alcoholic hydroxyl group by a peristaltic pump under stirring;
[0075] 2-4) After the addition is completed, the reaction is continued at the temperature for 2 hours, the system is heated to 90°C, the solvent is removed by vacuum distillation, and the obtained resin is transferred to a vacuum oven at 70°C and a vacuum degree of -0.095 MPa to dry to constant weight to obtain an epoxy resin containing a PC segment structure, which is recorded as an epoxidized EP-PC resin of oligomer;
[0076] 3) EP-PC curing and casting preparation
[0077] 100 parts of oligomer epoxidized EP-PC resin are heated to 55°C by mass, 25 parts of curing agent diaminodiphenyl sulfone (DDS) and 3 parts of meta-xylylenediamine are added thereto, stirred evenly, and poured after vacuum removal of bubbles, and then cured according to a temperature program of 80°C / 1h+120°C / 1h+170°C / 1.5h to obtain a low-temperature tough epoxy resin containing a polycarbonate intermediate with good high and low temperature resistance.
[0078] Embodiment 4:
[0079] 1) Synthesis of low molecular weight PC-O
[0080] 1-1) 100 parts by mass of bisphenol A and 1.1 parts of catalyst zinc acetylacetonate are added to a tubular reactor, heated until the bisphenol A is melted, nitrogen is introduced under mechanical stirring, a water separator is installed, and the temperature is raised to 180° C.;
[0081] 1-2) adding 250 parts of dimethyl carbonate to the tubular reactor below the raw material liquid level by pumping under stirring, and keeping the temperature to react until no bubbles appear on the material liquid level in the tubular reactor;
[0082] 1-3) centrifuging the reaction product at 10000 rpm to remove the catalyst A therein, and vacuum drying;
[0083] 1-4) adding ethanol to the dried product at a mass ratio of 1:3, stirring and filtering to remove extremely low molecular weight components in the product, and drying the filter cake to obtain low molecular weight PC-O;
[0084] 2) Epoxidation modification of PC oligomers
[0085] 2-1) 100 parts by mass of an epoxy compound AG-80 epoxy resin containing no alcoholic hydroxyl group were added to a four-necked flask, nitrogen was introduced under stirring, and the temperature was raised to 60° C.;
[0086] 2-2) 20 parts of low molecular weight PC-O were dissolved in 80 parts of THF, and 6 parts of a catalyst mixture of boron trifluoride etherate and dimethylimidazole and 5 parts of DMF were added thereto to obtain a mixed solution;
[0087] 2-3) heating the four-necked flask to 80° C. and adding the mixed solution into the epoxy compound containing no alcoholic hydroxyl group by a peristaltic pump under stirring;
[0088] 2-4) After the addition is completed, the reaction is continued at the temperature for 2 hours, the system is heated to 90°C, the solvent is removed by vacuum distillation, and the obtained resin is transferred to a vacuum oven at 70°C and a vacuum degree of -0.095 MPa to dry to constant weight to obtain an epoxy resin containing a PC segment structure, which is recorded as an epoxidized EP-PC resin of oligomer;
[0089] 3) EP-PC curing and casting preparation
[0090] 100 parts of oligomer epoxidized EP-PC resin by mass were heated to 75°C, 30 parts of curing agent diaminodiphenylmethane (DDM) and 5 parts of polyetheramine D230 were added thereto, stirred evenly, and poured after vacuum removal of bubbles, and then cured according to a temperature program of 80°C / 1h+120°C / 1h+170°C / 1.5h to obtain a low-temperature tough epoxy resin containing a polycarbonate intermediate with good high and low temperature resistance.
[0091] Embodiment 5:
[0092] 1) Synthesis of low molecular weight PC-O
[0093] 1-1) 100 parts by mass of bisphenol A and 1.2 parts by mass of a mixture of zirconium acetylacetonate and zinc acetylacetonate catalysts are added to a tubular reactor, heated until the bisphenol A is melted, nitrogen is introduced under mechanical stirring, a water separator is installed, and the temperature is raised to 180° C.;
[0094] 1-2) adding 300 parts of dimethyl carbonate to below the raw material liquid level of the tubular reactor by pumping under stirring, and keeping the temperature to react until no bubbles appear on the material liquid level in the tubular reactor;
[0095] 1-3) centrifuging the reaction product at 10000 rpm to remove the catalyst A therein, and vacuum drying;
[0096] 1-4) adding ethanol to the dried product at a mass ratio of 1:3, stirring and filtering to remove extremely low molecular weight components in the product, and drying the filter cake to obtain low molecular weight PC-O;
[0097] 2) Epoxidation modification of PC oligomers
[0098] 2-1) 100 parts by mass of a mixture of TDE-85 epoxy resin and AG-80 epoxy resin, epoxy compounds not containing alcoholic hydroxyl groups, were added to a four-necked flask, nitrogen was introduced, and the temperature was raised to 60° C.;
[0099] 2-2) 35 parts of low molecular weight PC-O were dissolved in 120 parts of THF, and then 3 parts of catalyst DMP-30 and 1 part of DMF were added thereto to obtain a mixed solution;
[0100] 2-3) heating the four-necked flask to 82° C. and adding the mixed solution to the epoxy compound containing no alcoholic hydroxyl group by a peristaltic pump under stirring;
[0101] 2-4) After the addition is completed, the reaction is continued at the temperature for 2 hours, the system is heated to 90°C, the solvent is removed by vacuum distillation, and the obtained resin is transferred to a vacuum oven at 70°C and a vacuum degree of -0.095 MPa to dry to constant weight to obtain an epoxy resin containing a PC segment structure, which is recorded as an epoxidized EP-PC resin of oligomer;
[0102] 3) EP-PC curing and casting preparation
[0103] 100 parts by mass of the epoxidized EP-PC resin of the oligomer are heated to 65°C, 30 parts of the curing agent diaminodiphenyl sulfone (DDS) are added thereto, stirred evenly, and poured after vacuum removal of bubbles, and then cured according to the temperature program of 80°C / 1h+120°C / 1h+170°C / 1.5h to obtain a low-temperature tough epoxy resin containing a polycarbonate intermediate with good high and low temperature resistance.
[0104] Embodiment 6:
[0105] 1) Synthesis of low molecular weight PC-O
[0106] 1-1) 100 parts by mass of bisphenol A and 0.8 parts of catalyst calcium acetylacetonate are added to a tubular reactor, heated until the bisphenol A is melted, nitrogen is introduced under mechanical stirring, a water separator is installed, and the temperature is raised to 185° C.;
[0107] 1-2) adding 280 parts of dimethyl carbonate to the tubular reactor below the raw material liquid level by pumping under stirring, and keeping the temperature to react until no bubbles appear on the material liquid level in the tubular reactor;
[0108] 1-3) centrifuging the reaction product at 10000 rpm to remove the catalyst A therein, and vacuum drying;
[0109] 1-4) adding ethanol to the dried product at a mass ratio of 1:3, stirring and filtering to remove extremely low molecular weight components in the product, and drying the filter cake to obtain low molecular weight PC-O;
[0110] 2) Epoxidation modification of PC oligomers
[0111] 2-1) 100 parts by mass of TDE-85 epoxy resin and bisphenol A diglycidyl ether, an epoxy compound not containing alcoholic hydroxyl groups, were added to a four-necked flask, nitrogen was introduced, and the temperature was raised to 60° C.;
[0112] 2-2) 33 parts of low molecular weight PC-O were dissolved in 110 parts of THF, and 6 parts of catalyst boron trifluoride ether and 6 parts of DMF were added thereto to obtain a mixed solution;
[0113] 2-3) heating the four-necked flask to 80° C. and adding the mixed solution into the epoxy compound containing no alcoholic hydroxyl group by a peristaltic pump under stirring;
[0114] 2-4) After the addition is completed, the reaction is continued at the temperature for 2 hours, the system is heated to 90°C, the solvent is removed by vacuum distillation, and the obtained resin is transferred to a vacuum oven at 70°C and a vacuum degree of -0.095 MPa to dry to constant weight to obtain an epoxy resin containing a PC segment structure, which is recorded as an epoxidized EP-PC resin of oligomer;
[0115] 3) EP-PC curing and casting preparation
[0116] 100 parts by mass of the epoxidized EP-PC resin of the oligomer are heated to 70°C, 30 parts of the curing agent diaminodiphenylmethane (DDM) and 2 parts of polyetheramine D230 are added thereto, stirred evenly, and poured after vacuum removal of bubbles, and then cured according to the temperature program of 80°C / 1h+120°C / 1h+170°C / 1.5h to obtain a low-temperature tough epoxy resin containing a polycarbonate intermediate with good high and low temperature resistance.
[0117] Embodiment 7:
[0118] 1) Synthesis of low molecular weight PC-O
[0119] 1-1) 100 parts by mass of bisphenol A and 1 part of catalyst calcium acetylacetonate are added to a tubular reactor, heated until the bisphenol A is melted, nitrogen is introduced under mechanical stirring, a water separator is installed, and the temperature is raised to 185° C.;
[0120] 1-2) adding 200 parts of dimethyl carbonate to the tubular reactor below the raw material liquid level by pumping under stirring, and keeping the temperature to react until no bubbles appear on the material liquid level in the tubular reactor;
[0121] 1-3) centrifuging the reaction product at 10000 rpm to remove the catalyst A therein, and vacuum drying;
[0122] 1-4) adding ethanol to the dried product at a mass ratio of 1:3, stirring and filtering to remove extremely low molecular weight components in the product, and drying the filter cake to obtain low molecular weight PC-O;
[0123] 2) Epoxidation modification of PC oligomers
[0124] 2-1) 100 parts by mass of an epoxy compound AG-80 epoxy resin containing no alcoholic hydroxyl group were added to a four-necked flask, nitrogen was introduced under stirring, and the temperature was raised to 60° C.;
[0125] 2-2) 28 parts of low molecular weight PC-O were dissolved in 90 parts of THF, and 5 parts of catalyst boron trifluoride ether and 6 parts of DMF were added thereto to obtain a mixed solution;
[0126] 2-3) heating the four-necked flask to 80° C. and adding the mixed solution into the epoxy compound containing no alcoholic hydroxyl group by a peristaltic pump under stirring;
[0127] 2-4) After the addition is completed, the reaction is continued at the temperature for 2 hours, the system is heated to 90°C, the solvent is removed by vacuum distillation, and the obtained resin is transferred to a vacuum oven at 70°C and a vacuum degree of -0.095 MPa to dry to constant weight to obtain an epoxy resin containing a PC segment structure, which is recorded as an epoxidized EP-PC resin of oligomer;
[0128] 3) EP-PC curing and casting preparation
[0129] 100 parts by mass of the epoxidized EP-PC resin of the oligomer are heated to 70°C, 33 parts of the curing agent DDM and 2 parts of the polyetheramine are added thereto, stirred evenly, the bubbles are removed by vacuum and then poured, and then cured according to the temperature program of 80°C / 1h+120°C / 1h+170°C / 1.5h to obtain a low-temperature tough epoxy resin containing a polycarbonate intermediate with good high and low temperature resistance.
[0130] from Figure 1 It can be seen that the EP-PC resin synthesized in the present invention not only retains the ester group (1768cm -1 ), and retains sufficient epoxy functional groups (912-914 cm -1 ).
[0131] Table 1 shows the molecular weight information of the EP-PC resin obtained in the present invention. Thanks to the low molecular weight PC-O, the average molecular weight of the obtained EP-PC is also low, ensuring good processability of the resin.
[0132] Table 1. Molecular weight information and glass transition temperature of EP-PC resin
[0133]
[0134] from Figure 2It can be seen that the technology of the present invention has good universality, and the type of epoxy compound and the ratio of epoxy compound to PC-O can be selected according to application needs, thereby adjusting the glass transition temperature of the modified resin (uncured state).
[0135] from Figure 3 It can be seen that the mechanical properties of EP-PC resin at room temperature and 100°C are close to those of TDE-85 resin, but at -50°C, the elongation at break of EP-PC resin cured product increases significantly.
[0136] from Figure 4 It can be seen that thanks to the effectively introduced PC-O segments, the EP-PC resin cured product exhibits significant secondary relaxation behavior at low temperatures (about -70°C), while the tanδ curve of the TDE-85 resin with the same degree of cure is relatively flat in this range, and the secondary relaxation is not obvious. It is precisely because of this outstanding low-temperature secondary relaxation behavior that the EP-PC resin has excellent low-temperature mechanical properties.
Claims
1. A method for preparing a low-temperature tough epoxy resin containing a polycarbonate intermediate, characterized in that: 1) Synthesis of low molecular weight PC-O 1-1) 100 parts by mass of bisphenol A and 0.5-1.2 parts of catalyst A are added to a tubular reactor, heated until the bisphenol A is melted, nitrogen is introduced under mechanical stirring, a water separator is installed, and the temperature is raised to 180-185° C.; 1-2) adding 100 to 300 parts of dimethyl carbonate under stirring, and keeping the temperature to react until no bubbles appear on the liquid surface of the material in the tubular reactor; 1-3) centrifuging the reaction product to remove the catalyst A therein, and vacuum drying; 1-4) adding ethanol to the dried product at a mass ratio of 1:3, stirring and filtering to remove extremely low molecular weight components in the product, and drying the filter cake to obtain low molecular weight PC-O; 2) Epoxidation modification of PC oligomers 2-1) 100 parts by mass of an epoxy compound containing no alcoholic hydroxyl group are added to a four-necked flask, nitrogen is introduced under stirring, and the temperature is raised to 60° C.; 2-2) 20 to 35 parts of low molecular weight PC-O are dissolved in 70 to 120 parts of THF, and then 1 to 6 parts of catalyst B and 1 to 6 parts of DMF are added thereto to obtain a mixed solution; 2-3) heating the four-necked flask to 78-82° C. and adding the mixed solution to the epoxy compound containing no alcoholic hydroxyl group by a peristaltic pump under stirring; 2-4) After the addition is completed, the reaction is continued at the temperature for 2 hours, the system is heated to 90° C., the solvent is removed by vacuum distillation, and the obtained resin is transferred to a vacuum oven for drying to obtain an epoxy resin containing a PC segment structure, which is recorded as an epoxidized EP-PC resin of an oligomer; 3) EP-PC curing and casting preparation Take 100 parts of oligomer epoxidized EP-PC resin by mass and heat it to 50-75°C, add 25-35 parts of curing agent thereto, stir evenly, remove bubbles in vacuum and then pour, and then cure according to the temperature program of 80°C / 1h+120°C / 1h+170°C / 1.5h to obtain a low-temperature tough epoxy resin containing a polycarbonate intermediate with good high and low temperature resistance.
2. The method for preparing a low-temperature tough epoxy resin containing a polycarbonate intermediate according to claim 1, characterized in that: The catalyst A is one of calcium acetylacetonate, zinc acetylacetonate or zirconium acetylacetonate or a mixture of any proportions thereof.
3. The method for preparing a low-temperature tough epoxy resin containing a polycarbonate intermediate according to claim 1, characterized in that: The dimethyl carbonate is added below the raw material liquid level of the tubular reactor by pumping.
4. The method for preparing a low-temperature tough epoxy resin containing a polycarbonate intermediate according to claim 1, characterized in that: The molecular weight M of the low molecular weight PC-O is n =1700~2000.
5. The method for preparing a low-temperature tough epoxy resin containing a polycarbonate intermediate according to claim 1, characterized in that: The epoxy compound not containing alcoholic hydroxyl group is one of ethylene glycol glycidyl ether, bisphenol A glycidyl ether, TDE-85 epoxy resin or AG-80 epoxy resin, or a mixture of any proportion of the two or more thereof.
6. The method for preparing a low-temperature tough epoxy resin containing a polycarbonate intermediate according to claim 1, characterized in that: The catalyst B is one or a mixture of any proportion of boron trifluoride etherate, DMP-30 and dimethylimidazole.
7. The method for preparing a low-temperature tough epoxy resin containing a polycarbonate intermediate according to claim 1, characterized in that: The above 2-4) is dried in a vacuum oven at 70° C. and a vacuum degree of -0.095 MPa to constant weight.
8. The method for preparing a low-temperature tough epoxy resin containing a polycarbonate intermediate according to claim 1, characterized in that: The curing agent is one of diaminodiphenylmethane (DDM), diaminodiphenyl sulfone (DDS), polyetheramine D230, meta-phenylenediamine, diethyltoluenediamine, or a mixture of any proportions thereof.