A polyimide copolymer based on bisphenol A diether dianhydride monomer

Abstract

The present invention provides a polyimide copolymer based on bisphenol A type diether dianhydride monomer, characterized in that it is obtained by copolymerizing tetraamine containing a polysiloxane structure, bisphenol A type diether dianhydride and diamine; its synthesis steps include: S1 synthesis of tetraamine containing a polysiloxane structure; S2 synthesis of polyamic acid and S3 imidization reaction of polyamic acid. The tetraamine containing a polysiloxane structure is obtained by a click reaction between a siloxane containing a tetraene group and / or an epoxy group and a terminal mercaptoamine. The present invention introduces a soft organic siloxane segment into a polyamide copolymer, improves the thermal stability of the polyimide copolymer, and makes the copolymer have better softness and impact resistance; at the same time, the methylsiloxane structure significantly improves the hydrophobicity and greatly reduces the hygroscopicity of the polyimide copolymer, thereby preparing a polymer material having excellent high-temperature thermal stability, good mechanical strength, tensile deformation ability and lower humidity.

Description

Technical Field

[0001] The invention belongs to the field of polymer synthesis, and in particular relates to a polyimide copolymer based on bisphenol A type diether dianhydride monomer. Background Art

[0002] Polyimide (PI) is a type of high-performance polymer with an imide ring in the main chain. It has excellent mechanical properties, dielectric properties and insulation properties. In addition, polyimide has excellent performance in low and high temperature resistance, radiation resistance, corrosion resistance, etc., and is widely used in various fields such as adhesives, coatings, fibers, foams, medicine, aerospace and films.

[0003] Most traditional aromatic polyimides are synthesized from aromatic diamines and aromatic dianhydrides, and the aromatic benzene structure contained in them can enhance the heat resistance, mechanical properties and chemical resistance of the polymer. However, the aromatic benzene structure has a high conjugation effect and strong intermolecular interaction, which makes the processing of polyimide films difficult; the amide ring has high rigidity, so the polyimide material has a high modulus, poor softness and high brittleness; in addition, due to the strong polarity of the amide bond, polyimide has a strong water absorption capacity, which affects the life of the material in a hot and humid environment, thereby limiting its application in various fields. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a polyimide copolymer based on bisphenol A diether dianhydride monomer.

[0005] The present invention relates to a polyimide copolymer based on bisphenol A type diether dianhydride monomer, which is obtained by copolymerizing tetraamine containing a polysiloxane structure, bisphenol A type diether dianhydride and diamine; the tetraamine containing a polysiloxane structure is obtained by a thiol-ene click reaction and / or a thiol-epoxy click reaction between a siloxane containing a tetraene group and / or an epoxy group and a terminal thiol amine;

[0006] As used herein, the term "siloxane containing tetraalkenyl and / or epoxy groups" includes siloxane containing four alkenyl groups, siloxane containing four epoxy groups, and siloxane containing both alkenyl and epoxy groups in the molecule and the sum of the number of alkenyl and epoxy groups is four; in the "siloxane containing tetraalkenyl and / or epoxy groups", there is no particular restriction on the position of the alkenyl and / or epoxy groups. It should be noted that the alkenyl and / or epoxy groups at the end groups have a higher reaction rate than the alkenyl and / or epoxy groups at the side chains, and the required reaction time is shorter. The reaction rate can be increased by adjusting the reaction temperature and changing the amount of catalyst.

[0007] As used herein, the term "terminal thiol amine" is an organic compound containing both a terminal thiol group and a primary amino group, including aliphatic primary / amides substituted with terminal thiol groups, benzyl (acyl) amines substituted with terminal thiol groups, nitrogen-containing heterocycles substituted with terminal thiol primary amino groups, and fatty acids (esters) substituted with terminal thiol primary amino groups; and because the click reaction can be completed in a very short time, common functional groups such as carboxyl, carbonyl, ester groups, etc. will not affect the click reaction, and therefore, other substituent groups in the "terminal thiol amine" molecule are not particularly limited.

[0008] The polyimide copolymer based on bisphenol A diether dianhydride monomer comprises the following steps of preparing the copolymer:

[0009] S1: Synthesis of tetraamine containing polysiloxane structure: Stirring tetraene- and / or epoxy-containing siloxane with terminal mercaptoamine under ultraviolet irradiation and catalyst to cause mercapto-ene click reaction and / or mercapto-epoxy click reaction; Precipitating the obtained viscous mixture in 10 volumes of ethanol three times to remove unreacted reactants and catalyst; Finally, the precipitate was vacuum dried at 60° C. to obtain tetraamine containing polysiloxane structure;

[0010] S2: Synthesis of polyamic acid: under nitrogen or inert gas atmosphere, add tetraamine containing polysiloxane structure into organic solvent, stir and dissolve at 0-20°C, add bisphenol A diether dianhydride in batches, mix and react for 6-12h under nitrogen or inert gas atmosphere; then continue to add organic solvent containing diamine, continue condensation reaction at 0-20°C for 6-12h to obtain material containing polyamic acid; too high reaction temperature increases reactivity, increases molecular weight, and causes viscosity of precursor composition to increase too fast.

[0011] S3: Imidization reaction of polyamic acid: first add excess imidization agent and acetic anhydride to the material containing polyamic acid obtained in S2, heat up to 50-60°C, and stir to react for 5-7h; then continue to heat up to 90-100°C and stir to react for 10-30min to form a high molecular weight polyimide solution; after the solution is cooled to room temperature, precipitate polyimide with ethanol, filter, and continue to rinse with ethanol for 3 times. After suction filtration, vacuum dry at 60°C for 18h-24h, then continue to heat up to 150°C and continue to dry for 6-18h to obtain a polyimide copolymer.

[0012] Preferably, in step S1, the molar ratio of the tetraene- and / or epoxy-containing siloxane to the terminal mercaptoamine is 1:(4.01-4.05); and the molar amount of the catalyst is 0.12%-0.25% of the molar amount of the tetraene- and / or epoxy-containing siloxane.

[0013] Preferably, the tetraamine containing a polysiloxane structure in step S2 is 3% to 15% of the total molar amount of the diamine and the tetraamine containing a polysiloxane structure; the molar amount of bisphenol A type diether dianhydride is 95% to 105% of the total molar amount of the amine groups in the diamine and the tetraamine containing a polysiloxane structure.

[0014] Preferably, when the thiol-ene click reaction occurs in step S1, the wavelength of the ultraviolet irradiation is 300-450 nm, and the irradiation time is 20-40 min; and the catalyst is a free radical initiator and / or a photobase generator.

[0015] Preferably, when the thiol-epoxy click reaction occurs in step S1, the wavelength of the ultraviolet irradiation is 200 to 320 nm, and the irradiation time is 40 to 60 min; the catalyst is a photobase generator and / or a photobase generator

[0016] Preferably, when the thiol-ene click reaction and the thiol-epoxy click reaction occur in step S1, the catalyst is selected from a combination of the above-mentioned photobase generator and a free radical initiator, and the thiol-epoxy polymerization is initiated by a strong base and the thiol-ene polymerization is initiated by a free radical.

[0017] Preferably, the free radical initiator is selected from azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, tri(pentafluorophenyl)boron, dimethylphenylphosphine, tri-n-butylphosphine, triisopropylphosphine, tribenzylphosphine, tricyclopentylphosphine, tri(dimethylamino)phosphine, tripyrrolidinophosphine, tri-n-octylphosphine, diphenyl ether, benzoin, benzoin dimethyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, benzoyl oxide, benzoyl peroxide tert-butyl ester and methyl ethyl ketone peroxide, benzophenone, 2,4-dihydroxybenzophenone, thiopropoxythioxanthone, 2 -one or more of isopropylthioxanthone; the photobase generator is selected from 1,8-bisdimethylaminonaphthalene, tetrabutylammonium fluoride, benzyltriethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium hydrogen sulfate, dihydrotrifluorotetrabutylammonium, 1,5,7-triazidobicyclo (4.4.0) dec-5-ene, 1,8-diazabicyclo (5.4.0) undec-7-ene (DBU), 1,5-diazabicyclo (4.3.0) non-5-ene, sodium tetraphenylborate, sodium tetra(p-tolyl)borate, and tetra(4-chlorophenyl)borate.

[0018] In the early stage of the click reaction, the reaction rate is relatively fast and the reaction products are oligomers. Therefore, in order to prevent the oligomers from connecting to each other to form long chains, the reaction time should not be too long. Since the thiol-ene click reaction is faster than the thiol-epoxy click reaction at the same concentration, when the click reaction contains epoxy groups, the stirring rate and reaction time can be appropriately extended to ensure sufficient reaction.

[0019] Preferably, the organic solvents in steps S1 and S2 are the same and are selected from one or more of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-methylpropionamide (DMPA), N,N-diethylformamide (DEF), N,N-diethylacetamide (DEAc), N,N-diethylpropionamide (DEPA), dimethyl sulfone (MSN), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), and N-ethylpyrrolidone (NEP); the organic solvent must be dehydrated before use: using benzophenone as an indicator, adding metallic sodium to the organic solvent for heat reflux dehydration until the solution turns dark blue; finally, freshly distilling it under normal pressure for use.

[0020] Preferably, the process conditions for the imidization in step S3 are: first increase the temperature to 300°C to 450°C at a rate of 5±1°C / min, maintain for 5 to 30 minutes, and then decrease to room temperature at a rate of 5±1°C / min.

[0021] Preferably, the amount of acetic anhydride and the imidization agent in step S3 is equivalent to 2-4 times the total molar amount of amino groups; the imidization agent is selected from one of triethylamine, low alkyl imidazole, low alkyl pyridine, picolinoline, and quinoline; the low alkyl imidazole includes but is not limited to imidazole, 1,2-dimethylimidazole, N-methylimidazole, N-benzyl-2-methylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole and 5-methylbenzimidazole; the low alkyl pyridine includes pyridine, 3,5-lutidine, 3,4-lutidine, 2,5-lutidine, 2,4-lutidine and 4-n-propylpyridine; quinoline includes but is not limited to isoquinoline, sec-butylquinoline, biquinoline, 2-amino-3,8-dimethylquinoline, dibenzoquinoline, and pyrazinequinoline.

[0022] Preferably, the diamine is selected from one or more of p-phenylenediamine, m-phenylenediamine, 4,4-oxydiphenylamine, 3,4-diaminophenyl ether, diaminodiphenyl sulfone, 4,4-diaminotriphenyl-p-phenylenediamine, 2,5-diaminotoluene, 2,6-naphthalenediamine, diaminobiphenyl, 4,4-diamino-2,2-dimethylbiphenyl, 3,3-dimethyl-4,4-diaminodiphenylmethane, 4,4-diaminobenzanilide, 2,6-diaminopyridine, 4-phenyl-2,6-bis(4-aminophenyl)pyridine, and 3,6-diaminocarbazole.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The polyimide copolymer provided by the present invention introduces a soft organic siloxane segment, which can greatly improve the adhesion of the polyimide copolymer to metals or silicon-containing inorganic materials; the siloxane chain bond is long and the rotation energy barrier is low, which can improve the modulus strength of the polyimide and reduce the stress caused by external forces, so that the copolymer has better softness, low-temperature toughness and impact resistance; at the same time, the tetraamine of the polysiloxane structure contains Si-O bonds with large bond energy, which can improve the thermal stability and flame retardancy of the polyimide after copolymerization with bisphenol A type diether dianhydride. In addition, the methylsiloxane structure significantly improves the hydrophobicity of the polyimide and greatly reduces the hygroscopicity of the polyimide, which is conducive to extending the life of the polyamide copolymer material in a hot and humid environment.

[0025] The present invention adds a tetraamine containing a polysiloxane structure to a conventional copolymerization system of diamine and bisphenol A type diether dianhydride to obtain a branched polyimide. Since the branched polyimide has multiple end groups, it develops from a central point to form a regular multi-branched polymer, and can have relatively more segments under the same solid content and viscosity conditions, giving the film-forming material relatively better mechanical properties.

[0026] The invention provides a polyimide copolymer based on bisphenol A diether dianhydride monomer, which uses a mercapto-olefin and / or mercapto-epoxy click reaction to achieve end group conversion and obtain a highly branched tetraamine structure. The reaction is simple and fast, the conditions are mild, the yield is high, it is green and environmentally friendly, and there are almost no by-products. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] 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 or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 Infrared spectra of the polyimide copolymers of Examples 1 to 4. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described in detail below in conjunction with several preferred embodiments and the accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments. The contents not described in detail in the specification of the present invention belong to the known technology of professional and technical personnel in this field.

[0030] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0031] In the description provided herein, the terms "comprising," "is," "containing," "having," and "including" are used in an open-ended manner and should therefore be interpreted to mean "including but not limited to." When an article, composition of matter, or method is claimed or described as "comprising" various steps or components, the apparatus, system, or method may also "consist essentially of" or "consist of" the various steps or components, unless otherwise stated.

[0032] Unless otherwise defined, the experimental materials used in the following examples and comparative examples can be purchased from conventional biochemical reagent companies.

[0033] Example 1

[0034] Preparation of a polyimide copolymer based on bisphenol A diether dianhydride monomer:

[0035] S1: Add 2.0 mmol of tetrakis(dimethylvinylsiloxy)silane (CAS No.: 60111-54-8), 8.02 mmol of 3-mercaptobenzamide (CAS No.: 569339-15-7) and 10 mL of anhydrous DMAc to a 50 mL beaker with a mechanical stirrer, mix well, add 0.4 mmol of 1,8-bis(dimethylaminonaphthalene) as a catalyst, and stir until completely dissolved; then keep stirring (speed 50 rpm) and irradiate under ultraviolet light (Intelli-Ray 600 type ultraviolet curing box, ultraviolet light irradiation distance 15 cm, room temperature) for 30 minutes to obtain a viscous mixture; after vacuum removal of DMAc, the mixture was precipitated three times in 10 volumes of ethanol to remove unreacted reactants and catalysts; the precipitate was vacuum dried at 60°C for 24 hours to obtain tetraamine 1 containing a tetrasiloxane structure with a yield of 97.6%. The structural formula of 1 is:

[0036]

[0037] The AVANCE superconducting nuclear magnetic resonance spectrometer of Bruker Company of Germany was used, and the solvent was deuterated chloroform (CDCl3, without internal standard) to test the nuclear magnetic hydrogen spectrum (400MHz) and nuclear magnetic carbon spectrum (101MHz) of the polyimide copolymer. The results are: 1 H NMR (400MHz, ppm): δ7.87~7.45 (16H,4×Ar- H ), 7.76(Ar-(N H 2)-C=O), 2.47 (8H, 4×-SC H2-), 1.03~0.69(8H,4×-SiC H 2-), 0.09(12H,4×Si-C H 3). 13 C NMR (101MHz, ppm): δ167.83(4C,Ar-(NH2)- C =O), 135.28~123.96 (24C, 6×O= C -Ar-S-), 36.7(4C,4×-S- C H2-), 13.09(4C,4×-Si C H2-), 1.26(8C,8×-Si C H3).

[0038] S2: Under N2 atmosphere, 0.2 mmol of tetraamine 1 containing tetrasiloxane structure was dissolved in 8 mL of anhydrous DMAc in a 50 mL three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser, and stirred to dissolve at 0°C; 2.03 mmol of bisphenol A diether dianhydride was added in batches, and stirred to react for 12 h under N2 atmosphere and 0°C; 2 mL of DMAc solution containing 1.6 mmol of diaminodiphenyl sulfone (CAS No.: 80-08-0) was added, and the reaction was continued under N2 atmosphere and 0°C with stirring for 24 h to obtain a material containing polyamic acid;

[0039] S3: Add excess triethylamine and acetic anhydride to the material containing polyamic acid obtained in S2, heat to 60°C, and stir to react for 5 hours; then continue to heat to 100°C and stir to react for 20 minutes to form a high-molecular polyimide solution; after the solution is cooled to room temperature, filter out the polyimide with ethanol precipitation, rinse with ethanol three times, filter, and vacuum dry at 60°C for 24 hours, then continue to heat to 150°C and continue to dry for 12 hours to obtain a polyimide copolymer.

[0040] Example 2

[0041] A polyimide copolymer based on bisphenol A type diether dianhydride monomer, the preparation process of which is compared with that of Example 1, wherein the tetraolefinic and / or epoxy siloxane used in step S1 is methacryloxypropyl tris(vinyldimethylsiloxy)silane (CAS No.: 17096-10-5), the terminal mercaptoamine used is 3-mercapto-1-propylamine (CAS No.: 462-47-5), the catalyst used is azobisisobutyronitrile, the organic solvent used is anhydrous DMF, and the other conditions are the same as those of Example 1, to obtain tetraamine 2 containing a tetrasiloxane structure, with a yield of 99.2%; the structure thereof is as follows:

[0042]

[0043] 1H NMR: δ7.36 (8H, 4×-N H 2), 4.11(2H,OC H 2-), 3.8(8H,4×NH2C H 2-), 3.55(1H, -C H (CH3)-COO-), 3.2~3.02(2H,-SC H 2-CH(CH3)-), 2.64(8H,4×NH2CH2C H 2-), 2.55(8H,4×NH2(CH2)2-C H 2S-), 2.47(6H,3×-SC H 2-CH2Si-), 1.51(2H,-SiCH2-C H 2-CH2O-), 1.34~1.23(2H,-SiC H 2-(CH2)2O-), 1.03~0.6(6H,3×-SCC H 2Si-), 0.21(2H,-SiC H 2Si-), 0.12~0.09(18H,6×-SiC H 3). 13 C NMR: δ175.1(1C, -O- C =O), 66.91(1C, -COO C H2-), 45.2(4C,4×NH2-CH2-), 41.44(1C,- C H(CH3)-C=O), 36.7~29.7(8C,8×-S C H2-(CH2)2NH2), 26.1(4C, 4×- C H2CH2NH2), 16.31(1C,-O-(CH2)2- C H2-Si-), 16.28(1C,- C H(CH3)-), 13.09(-SCH2- C H2-Si-), 2.4(1C,-Si C H2Si-), 1.26(6C, 6×-Si C H3).

[0044] The organic solvent used in step S2 is anhydrous DMF, the diamine used is 3,6-diaminocarbazole (CAS No.: 86-71-5), and the imidization agent used in step S3 is N-methylimidazole; the other conditions are the same as in Example 1 to obtain a polyimide copolymer.

[0045] Example 3

[0046] A polyimide copolymer based on bisphenol A type diether dianhydride monomer, the preparation process of which is compared with that of Example 1, wherein the tetraene and / or epoxy siloxane used in step S1 is 2,4,6,8-tetramethyl-2,4,6,8-tetra[3-(ethylene oxide methoxy)propyl]cyclotetrasilane (CAS No.: 60665-85-2), the terminal mercaptoamine used is 4-aminobenzenethiol (CAS No.: 1193-02-8), the catalyst used is tetrabutylammonium fluoride (TABF), the rotation speed is 100 rpm, the click reaction time is 60 min, the organic solvent used is anhydrous DMSO, and the other conditions are the same as those of Example 1, to obtain tetraamine 3 containing a tetrasiloxane structure, with a yield of 94.2%; the structure is as follows:

[0047]

[0048] 1 H NMR: δ8.21~6.78(16H,4×Ar- H ), 5.63(4H,4×-SC H -), 4.58(4H,4×Ar-N H 2), 4.43(8H,4×-OC H 2-CH(OH)S-), 4.36(4H,4×-O H ), 3.87~3.51(8H,4×-OC H 2(CH2)2Si-), 1.51(8H,4×-SiCH2C H 2-), 1.34~1.23(8H,4×-Si-C H 2-), 0.32(12H,4×-SiC H 3). 13 C NMR: δ148~112(24C,4×-S-Ph-NH2), 67.9(4C,4×-S C H(OH)-), 70.9(1C, -O- C H2CH(OH)S-), 66.9(4C,4×O- C H2-(CH2)2Si-), 26.3(4C,4×- C H2CH2Si-), 16.31(4C, -Si C H2-), 1.26(4×-Si C H3).

[0049] The organic solvent used in step S2 is anhydrous DMSO, the diamine used is 2,6-naphthalenediamine (CAS No.: 2243-67-6), and the imidization agent used in step S3 is 3,5-lutidine; the other conditions are the same as in Example 1 to obtain a polyimide copolymer.

[0050] Example 4

[0051] A polyimide copolymer based on bisphenol A type diether dianhydride monomer, in the preparation process, the tetraene and / or epoxy siloxane used in step S1 is methyl methacrylate trioxycyclosiloxane (CAS No. 921214-21-3), the terminal mercaptoamine used is mercaptoacetanilide carbamate (CAS No.: 64046-58-8), and the catalyst used is a compound of 1,5,7-triazidobicyclo (4.4.0) dec-5-ene (TBD) and 2-isopropylthioxanthone in a molar ratio of 1:3. The click reaction time is 50 minutes, the organic solvent used is anhydrous NMP, and the other conditions are the same as in Example 1, and the tetraamine 4 containing a tetrasiloxane structure is obtained with a yield of 95.2%; the structure is as follows:

[0052]

[0053] 1 H NMR: δ9.19 (4H, 4×Ar-N H -C=O), 7.62~7.13(24H,4×-NH-Ph), 6.56(4H,4×-C H -S-), 5.0(8H,4×- H 2N-COO-), 4.17~4.15(2H,-COOC H 2-), 3.93~3.91(4H,4×-C H (OH)-), 3.87~3.48(16H,8×-OC H 2-), 3.55(1H, -C H (CH3)-), 3.43~3.42(4H,4×-O H ), 3.02~2.62(8H,4×-SC H 2-), 1.51(8H,4×-SiCH2C H 2-), 1.34(3H, -CHC H 3), 1.23(8H,4×-SiC H 2-), 0.32~0.2(12H,4×-SiC H 3). 13 C NMR: δ175.09 (1C, - C OOCH2-), 165.58 (4C, 4×Ar-NH-C =O), 157.41(4C,4×NH2- C OO-), 139.2~120.28(24C,4×-NH-Ph), 86.6(4C,4×- C HS-), 73~70.9(3C,3×-O C H 2- CH(OH)-CS), 69.1~67.67(4C,4×- C H(OH)-), 66.91(4C,4×-O C H2-CH2CH2Si-), 65.88(1C, -COO C H(OH)-), 37.35(3C,3×-S C H2CH(OH)-), 30.48(1C,-S C H2CH(CH3)-), 26.3(4C,4×-SiCH2 C H2-), 16.31(4C,4×-Si C H2-), 1.26(4C,4×-Si C H3).

[0054] The organic solvent used in step S2 is anhydrous NMP, the diamine used is diaminobiphenyl (CAS No.: 621-95-4), the imidization agent used in step S3 is biquinoline, and the other conditions are the same as in Example 1 to obtain a polyimide copolymer.

[0055] The chemical composition of the polyimide copolymers obtained in Examples 1 to 4 was tested using a Nicolet 6700 Fourier transform infrared spectrometer from Thermo Fisher Scientific. The chemical composition of the polyimide copolymers obtained in Examples 1 to 4 was tested using a potassium bromide tablet with a wavelength range of 400-4000 cm -1 , resolution 4cm -1 The results are attached. Figure 1 .

[0056] Depend on Figure 1 , Examples 1 to 4 all showed absorption of chemical bonds related to Si atoms: 1130 cm -1 It is the stretching vibration of Si-O-Si bond, 836cm -1 The peak of Si-C stretching vibration is 807 cm -1 The peak at 3430cm is the Si-O stretching vibration peak, indicating that no Si-O-Si chain breakage occurs during the click reaction and no coupling reaction occurs in the polymer molecules. -1 The absorption peak near is the NH stretching vibration. The polyimide copolymer molecules of Examples 3 and 4 contain both -OH and NH at 3200-3400 cm-1 The absorption peak becomes broadened. 2833cm -1 、2916cm -1 The stronger absorption peaks at 1405cm are the stretching characteristic peaks of -CH2 and -CH3. -1 The peak at 1235cm is the stretching vibration absorption peak of CN. -1 The stronger peak at 1658cm is the characteristic absorption peak of ether bond (COC). -1 There are symmetric and asymmetric stretching vibration peaks of C=O of amide structure. Examples 1, 2, and 4 have 1778 and 1720 nm -1 There is a C=O bending vibration absorption peak at 690cm -1 and 770cm -1 They are the out-of-plane bending vibration and ring bending vibration of the benzene ring respectively.

[0057] Example 5

[0058] A polyimide copolymer based on bisphenol A diether dianhydride monomer. Compared with Example 1, the preparation process of the polyimide copolymer is as follows: the molar amount of tetraamine 1 containing a tetrasiloxane structure in step S2 is changed to 3% of the total molar amount of tetraamine 1 containing a tetrasiloxane structure and diamine; the other steps are the same as Example 1.

[0059] Example 6

[0060] A polyimide copolymer based on bisphenol A diether dianhydride monomer. Compared with Example 1, the preparation process of the polyimide copolymer is as follows: the molar amount of the tetraamine 1 containing a tetrasiloxane structure in step S2 is changed to 15% of the total molar amount of the tetraamine 1 containing a tetrasiloxane structure and the diamine; the other steps are the same as Example 1.

[0061] Comparative Example 1

[0062] A polyimide homopolymer is obtained by polymerization of bisphenol A type diether dianhydride and diamine, and its preparation process is as follows:

[0063] S1: Under N2 atmosphere, 2.0 mmol of diaminodiphenyl sulfone was dissolved in 10 mL of anhydrous DMAc in a 50 mL three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser, and stirred to dissolve at 0°C; 2.03 mmol of bisphenol A diether dianhydride was added in batches, and the mixture was stirred and reacted under N2 atmosphere at 0°C for 24 h to obtain a material containing polyamic acid;

[0064] S2: Add excess triethylamine and acetic anhydride to the polyamic acid-containing material obtained in S1, heat to 60°C, and stir to react for 5 hours; then continue to heat to 100°C and stir to react for 20 minutes to form a high-molecular polyimide solution; after the solution is cooled to room temperature, precipitate the solution with 10 times the volume of ethanol, filter and wash the precipitate with ethanol three times, and vacuum dry at 60°C for 6 hours; then heat to 200°C and continue to vacuum dry for 24 hours to obtain a polyimide homopolymer.

[0065] Comparative Example 2

[0066] A polyimide homopolymer is obtained by polymerization of bisphenol A type diether dianhydride and tetraamine 1 containing a tetrasiloxane structure, and the preparation process is as follows:

[0067] S1: Under N2 atmosphere, 1.0 mmol of tetraamine 1 containing tetrasiloxane structure was dissolved in 10 mL of anhydrous DMAc in a 50 mL three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser, and stirred to dissolve at 0°C; 2.03 mmol of bisphenol A diether dianhydride was added in batches, and the mixture was stirred and reacted under N2 atmosphere at 0°C for 24 h to obtain a material containing polyamic acid;

[0068] S2: Add excess triethylamine and acetic anhydride to the polyamic acid-containing material obtained in S1, heat to 60°C, and stir to react for 5 hours; then continue to heat to 100°C and stir to react for 20 minutes to form a high-molecular polyimide solution; after the solution is cooled to room temperature, precipitate the solution with 10 times the volume of ethanol, filter and wash the precipitate with ethanol three times, and vacuum dry at 60°C for 6 hours; then heat to 200°C and continue to vacuum dry for 24 hours to obtain a polyimide homopolymer.

[0069] The number average molecular weight (Mn), weight average molecular weight (Mw) and molecular weight distribution index (PDI) of the polyimide copolymers of Examples 1 to 6 and the polyimide homopolymers of Comparative Examples 1 to 2 were tested using an Agilent 1260 Infinity II high temperature gel permeation chromatography (GPC) system. Polystyrene was used as an external standard for calibration; HPLC grade 1,2,4-trichlorobenzene was used as an eluent with a flow rate of 1.0 mL / min; the injection volume was 100 μL, and the working column temperature was 150°C.

[0070] The polyimide copolymer in the present invention is a hyperbranched polymer, and the GPC test result is lower than the actual value. MALDI-TOF is used to measure the number average molecular weight of the polymer.

[0071] The viscosity of the polyimide copolymer was measured using an Ubbelohde viscometer (capillary diameter 0.65±0.05 mm) at a temperature of 25° C. and a blank solvent of NMP.

[0072] The glass transition temperature (T) of the polymers was measured using a TAQ20 differential scanning calorimeter (DSC) under a nitrogen atmosphere. g ). Before the test, the sample was dried at 120℃ for 4h, 6-8mg of sample was weighed, and the test was carried out in N2 atmosphere with a nitrogen flow rate of 20mL / min; the first heating rate was 20℃ / min, and the heating temperature range was 40-400℃; it was kept at 400℃ for 2min; then the temperature was rapidly reduced, and the cooling temperature range was 40-400℃; it was kept at 40℃ for 2min; then the second heating was carried out, and the heating rate was 20℃ / min, and the heating temperature range was 40-400℃.

[0073] A TAQ500 thermogravimetric analyzer was used with a nitrogen flow rate of 50 mL / min, a heating rate of 10 °C / min, and a test range of room temperature to 800 °C. The polymer sample was dried in an oven at 120 °C for 4 h before testing to eliminate the interference of the solvent in the film, and then 2 to 3 mg was accurately weighed for testing.

[0074] The test results of Examples 1 to 6 and the comparative example samples are shown in Table 1.

[0075] Table 1 Test results of Examples 1 to 6 and Comparative Examples

[0076]

[0077] In the table, T g —Glass transition temperature; T 5％ —5% thermal weight loss temperature; T ma —Maximum thermal weight loss temperature.

[0078] From Table 1, the viscosity of the comparative example and the example is higher than 0.40 dL / g. The viscosity of the polyimide copolymer of Example 1 is lower when it has a molecular weight equivalent to that of the polyimide homopolymers of Comparative Examples 1 and 2, because of the introduction of flexible chains such as sulfide bonds in the polyimide copolymer. Since the tetraamine 3 containing a tetrasiloxane structure has a large steric hindrance and a lower reaction activity than diaminodiphenyl sulfone, the viscosity of Comparative Example 2 is lower than that of Comparative Example 1.

[0079] From Table 1, the polyimide copolymers of Examples 1 to 6 exhibit good thermal stability. The temperature range of the glass transition temperature is 418 to 449°C, the temperature of thermal weight loss at 5% is 548 to 578°C, and the maximum thermal weight loss temperature is 565 to 596°C, which shows that the presence of silicon oxygen bonds and silicon methyl groups improves the thermal stability of the polyimide copolymer, and the presence of thioether bonds does not affect its thermal stability. The homopolymer of Comparative Example 1 does not contain tetramine, and its T gThe value is less than 400°C, indicating that the introduction of tetraamine with branched structure can enhance the cross-linking network density of the polymer system and improve the heat resistance of the polymer. The molar ratio of tetraamine 1 to diamine in tetrasiloxane structure in Example 1 and Examples 5-6 is different. As the molar ratio of tetraamine 1 increases, the molecular weight tends to decrease as a whole. On the one hand, the reaction steric hindrance caused by the hyperbranched structure of tetraamine increases, and on the other hand, the silyl methyl page reduces the reaction activity of diamine, thereby affecting the molecular weight of the polymer. However, within the scope of the present invention, the number average molecular weight is still generally higher than 60,000.

[0080] Test Case

[0081] The polyimide copolymer solids obtained in Examples 1 to 6 and the comparative example were respectively dissolved in NMP, stirred until completely dissolved, filtered through a 60-100 mesh (250-150 μm) double-layer nylon cloth, and then defoamed under vacuum conditions for 1 hour to obtain a polyimide casting solution with a solid content of 25%;

[0082] The casting solution was cast on a clean glass plate, and then placed in a forced air drying oven, first dried at 60°C for 12 hours to volatilize DMSO, and then heated to 150°C and continued to dry for 12 hours to ensure that trace amounts of DMSO were completely removed, to obtain a cured polymer film;

[0083] The glass plate was immersed in deionized water, the film was slowly peeled off, and dried at 100° C. for 6 h to obtain a polyimide (PI) film with a thickness of 70 to 80 μm.

[0084] The film samples were tested as follows:

[0085] 1) Water absorption rate: Cut the PI film sample into a rectangular shape with a length and width of 150mm×100mm, and pre-dry it in an oven at 100℃ for 12 hours to obtain a sample with a dry weight of m1(g). After soaking it in water at room temperature for 24 hours, measure the weight of the film after water absorption m2(g). The water absorption rate is (m2-m1) / m1×100%.

[0086] 2) Linear thermal expansion coefficient (CTE) test: The test was conducted using a German NetzschTMA402F3 thermomechanical analyzer with a temperature range of 50-250°C, a heating rate of 5°C / min, and a static force of 0.05 N. The CTE value was the average value of the length change per 1°C between 100 and 200°C.

[0087] 3) Mechanical properties: According to GB / T 2567-2008, an Instron-5869 electronic tensile testing machine was used, with a sample size of (4.5-5.0) cm×0.6 cm, a load of 100 N, a tensile speed of 5 mm / min, and a test temperature of room temperature. Five parallel experiments were set for each sample, and the results were averaged.

[0088] The test data of the polyimide films prepared by the examples and comparative examples are shown in Table 2.

[0089] Table 2 Test data of polyimide films prepared in Examples and Comparative Examples

[0090] PI film Water absorption / % CTE Tensile strength / MPa Elongation at break / % Example 1 0.45 37 239 17 Example 2 0.51 34 243 18 Example 3 0.79 39 257 14 Example 4 0.85 43 260 16 Example 5 0.39 40 248 20 Example 6 0.48 32 234 24 Comparative Example 1 2.13 26 187 45 Comparative Example 2 1.45 29 206 34

[0091] From Table 2, by introducing tetraamine containing polysiloxane bonds and thioether bonds, the linear thermal expansion coefficient, tensile strength and modulus of the polymer film products are much higher than those of the comparative example, and the thermodynamic properties are better. The hydrophobic siloxane group can reduce the interaction between the polymer molecular chain and the water molecules, so that the PI film obtained by the embodiment is significantly lower than the comparative example in terms of water absorption; on the other hand, siloxane can improve the stretchability and elongation at break of the polymer film, and has better flexibility. In Examples 3 to 4, the hygroscopicity of the polyimide film is larger than that of other embodiments due to the introduction of hydroxyl groups by the ring opening of the epoxy group in the click reaction; however, the hydroxyl polar group can form hydrogen bonds with the carbonyl group in the molecule, which can improve the mechanical properties of the material and offset the weakening effect of flexible chains such as siloxane groups, so the tensile strength is better. The PI product of the polyimide copolymer provided by the present invention has high thermal stability, excellent mechanical strength, tensile deformation ability and lower moisture resistance.

[0092] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification with reference to the aforementioned embodiments, and obtained relatively ideal results.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A polyimide copolymer based on bisphenol A diether dianhydride monomer, characterized in that: The polysiloxane-containing tetraamine is obtained by copolymerizing bisphenol A diether dianhydride and diamine; the polysiloxane-containing tetraamine is obtained by a click reaction between a tetraene-containing and / or epoxy-containing siloxane and a terminal mercaptoamine; The synthesis steps of the polyimide copolymer of bisphenol A type diether dianhydride monomer include: S1: Synthesis of tetraamine containing polysiloxane structure: Siloxane containing tetraene group and / or epoxy group and terminal mercaptoamine are stirred under ultraviolet radiation and catalyst to cause mercapto-ene click reaction and / or mercapto-epoxy click reaction to obtain tetraamine containing polysiloxane structure; S2: Synthesis of polyamic acid: polycondensation of tetraamine containing polysiloxane structure, bisphenol A type diether dianhydride and diamine in an anhydrous organic solvent to obtain a material containing polyamic acid; S3: Imidization reaction of polyamic acid: acetic anhydride and an imidization agent are added to the polyamic acid-containing material obtained in S2 to carry out intramolecular dehydration reaction of the polyamic acid to obtain a polyimide copolymer.

2. A polyimide copolymer based on bisphenol A diether dianhydride monomer as claimed in claim 1, characterized in that: In step S1, the molar ratio of the tetraene- and / or epoxy-containing siloxane to the terminal mercaptoamine is 1:(4.01-4.05); the molar amount of the catalyst is 0.12%-0.25% of the molar amount of the tetraene- and / or epoxy-containing siloxane.

3. A polyimide copolymer based on bisphenol A type diether dianhydride monomer as claimed in claim 1, characterized in that: The molar amount of the tetraamine containing a polysiloxane structure in step S2 is 3% to 15% of the total molar amount of the diamine and the tetraamine containing a polysiloxane structure; the molar amount of bisphenol A type diether dianhydride is 95% to 105% of the total molar amount of the amine groups in the diamine and the tetraamine containing a polysiloxane structure.

4. A polyimide copolymer based on bisphenol A diether dianhydride monomer as claimed in claim 1, characterized in that: When the thiol-ene click reaction occurs in step S1, the ultraviolet irradiation wavelength is 300-450 nm, and the irradiation time is 20-40 min; the catalyst is a free radical initiator and / or a photobase generator; when the thiol-epoxy click reaction occurs in step S1, the ultraviolet irradiation wavelength is 200-320 nm, and the irradiation time is 40-60 min; the catalyst is a free radical initiator and / or a photobase generator.

5. A polyimide copolymer based on bisphenol A type diether dianhydride monomer as claimed in claim 4, characterized in that: The free radical initiator is selected from azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, tri(pentafluorophenyl)boron, dimethylphenylphosphine, tri-n-butylphosphine, triisopropylphosphine, tribenzylphosphine, tricyclopentylphosphine, tri(dimethylamino)phosphine, tripyrrolidinophosphine, tri-n-octylphosphine, diphenyl ether, benzoin, benzoin dimethyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, benzoyl oxide, benzoyl peroxide tert-butyl ketone and methyl ethyl ketone peroxide, benzophenone, 2,4-dihydroxybenzophenone, thiopropoxythioxanthone, 2-isopropyl The photobase generator is selected from one or more of 1,8-bis(dimethylaminonaphthalene), tetrabutylammonium fluoride, benzyltriethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium hydrogen sulfate, dihydrotrifluorotetrabutylammonium, 1,5,7-triazidobicyclo(4.4.0)dec-5-ene, 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU), 1,5-diazabicyclo(4.3.0)non-5-ene, sodium tetraphenylborate, sodium tetra(p-tolyl)borate, and tetra(4-chlorophenyl)borate.

6. A polyimide copolymer based on bisphenol A type diether dianhydride monomer as claimed in claim 4, characterized in that: When the thiol-ene click reaction and the thiol-epoxy click reaction occur in step S1, the catalyst is selected from the photobase generator and the free radical initiator.

7. A polyimide copolymer based on bisphenol A diether dianhydride monomer as claimed in claim 1, characterized in that: The organic solvents in steps S1 and S2 are the same and are selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-methylpropionamide, N,N-diethylformamide, N,N-diethylacetamide, N,N-diethylpropionamide, dimethyl sulfone, dimethyl sulfoxide, N-methylpyrrolidone, and N-ethylpyrrolidone; the organic solvent must be dehydrated before use.

8. A polyimide copolymer based on bisphenol A diether dianhydride monomer as claimed in claim 1, characterized in that: The reaction conditions of imidization in step S3 are: firstly increase the temperature to 300°C to 450°C at a rate of 5±1°C / min, and maintain for 5 to 30 minutes; then decrease the temperature to room temperature at a rate of 5±1°C / min.

9. A polyimide copolymer based on bisphenol A type diether dianhydride monomer as claimed in claim 1, characterized in that: The amount of acetic anhydride and imidization agent used in step S3 is equivalent to 2-4 times the total molar amount of amino groups; The imidization agent is selected from one of triethylamine, low alkyl imidazole, low alkyl pyridine, picolinate, and quinoline; The low alkyl imidazoles include imidazole, 1,2-dimethylimidazole, N-methylimidazole, N-benzyl-2-methylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole and 5-methylbenzimidazole; the low alkyl pyridines include pyridine, 3,5-dimethylpyridine, 3,4-dimethylpyridine, 2,5-dimethylpyridine, 2,4-dimethylpyridine and 4-n-propylpyridine; the quinolines include sec-butylquinoline, biquinoline, 2-amino-3,8-dimethylquinoline, dibenzoquinoline and pyrazinequinoline.

10. A polyimide copolymer based on bisphenol A diether dianhydride monomer according to claim 1, characterized in that: The diamine is selected from one or more of p-phenylenediamine, m-phenylenediamine, 4,4-oxydiphenylamine, 3,4-diaminophenyl ether, diaminodiphenyl sulfone, 4,4-diaminotriphenyl-p-phenylenediamine, 2,5-diaminotoluene, 2,6-naphthalenediamine, diaminobiphenyl, 4,4-diamino-2,2-dimethylbiphenyl, 3,3-dimethyl-4,4-diaminodiphenylmethane, 4,4-diaminobenzanilide, 2,6-diaminopyridine, 4-phenyl-2,6-bis(4-aminophenyl)pyridine, and 3,6-diaminocarbazole.

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