CN111002668A - Artificial graphite composite membrane and preparation method thereof - Google Patents
Artificial graphite composite membrane and preparation method thereof Download PDFInfo
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- CN111002668A CN111002668A CN201911317095.9A CN201911317095A CN111002668A CN 111002668 A CN111002668 A CN 111002668A CN 201911317095 A CN201911317095 A CN 201911317095A CN 111002668 A CN111002668 A CN 111002668A
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- artificial graphite
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- polyamic acid
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- 239000002131 composite material Substances 0.000 title claims abstract description 66
- 229910021383 artificial graphite Inorganic materials 0.000 title claims abstract description 64
- 239000012528 membrane Substances 0.000 title claims abstract description 46
- 238000002360 preparation method Methods 0.000 title claims abstract description 11
- 229920002678 cellulose Polymers 0.000 claims abstract description 51
- 239000001913 cellulose Substances 0.000 claims abstract description 51
- 239000002159 nanocrystal Substances 0.000 claims abstract description 48
- 229920005575 poly(amic acid) Polymers 0.000 claims abstract description 31
- 239000000203 mixture Substances 0.000 claims abstract description 26
- 239000000178 monomer Substances 0.000 claims abstract description 24
- GTDPSWPPOUPBNX-UHFFFAOYSA-N ac1mqpva Chemical compound CC12C(=O)OC(=O)C1(C)C1(C)C2(C)C(=O)OC1=O GTDPSWPPOUPBNX-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229920001721 polyimide Polymers 0.000 claims abstract description 18
- 238000006068 polycondensation reaction Methods 0.000 claims abstract description 15
- 125000003118 aryl group Chemical group 0.000 claims abstract description 14
- 150000004984 aromatic diamines Chemical class 0.000 claims abstract description 13
- 239000002904 solvent Substances 0.000 claims abstract description 13
- 239000012298 atmosphere Substances 0.000 claims abstract description 7
- 108010025899 gelatin film Proteins 0.000 claims abstract description 5
- 239000000126 substance Substances 0.000 claims abstract description 5
- 238000000034 method Methods 0.000 claims description 31
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 30
- 229910002804 graphite Inorganic materials 0.000 claims description 19
- 239000010439 graphite Substances 0.000 claims description 19
- WFDIJRYMOXRFFG-UHFFFAOYSA-N Acetic anhydride Chemical compound CC(=O)OC(C)=O WFDIJRYMOXRFFG-UHFFFAOYSA-N 0.000 claims description 9
- 238000003763 carbonization Methods 0.000 claims description 9
- 238000005087 graphitization Methods 0.000 claims description 9
- 229910052799 carbon Inorganic materials 0.000 claims description 7
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 claims description 6
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 claims description 6
- 125000000524 functional group Chemical group 0.000 claims description 5
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 4
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims description 4
- 239000003054 catalyst Substances 0.000 claims description 4
- 239000012024 dehydrating agents Substances 0.000 claims description 4
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 4
- AWJUIBRHMBBTKR-UHFFFAOYSA-N isoquinoline Chemical compound C1=NC=CC2=CC=CC=C21 AWJUIBRHMBBTKR-UHFFFAOYSA-N 0.000 claims description 4
- MFRIHAYPQRLWNB-UHFFFAOYSA-N sodium tert-butoxide Chemical compound [Na+].CC(C)(C)[O-] MFRIHAYPQRLWNB-UHFFFAOYSA-N 0.000 claims description 4
- HLBLWEWZXPIGSM-UHFFFAOYSA-N 4-Aminophenyl ether Chemical compound C1=CC(N)=CC=C1OC1=CC=C(N)C=C1 HLBLWEWZXPIGSM-UHFFFAOYSA-N 0.000 claims description 3
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 3
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 claims description 3
- NOGFHTGYPKWWRX-UHFFFAOYSA-N 2,2,6,6-tetramethyloxan-4-one Chemical compound CC1(C)CC(=O)CC(C)(C)O1 NOGFHTGYPKWWRX-UHFFFAOYSA-N 0.000 claims description 2
- YXZUDXLWSOZHFN-UHFFFAOYSA-N 2,3-diethylpyridine Chemical compound CCC1=CC=CN=C1CC YXZUDXLWSOZHFN-UHFFFAOYSA-N 0.000 claims description 2
- ZBMISJGHVWNWTE-UHFFFAOYSA-N 3-(4-aminophenoxy)aniline Chemical compound C1=CC(N)=CC=C1OC1=CC=CC(N)=C1 ZBMISJGHVWNWTE-UHFFFAOYSA-N 0.000 claims description 2
- YBRVSVVVWCFQMG-UHFFFAOYSA-N 4,4'-diaminodiphenylmethane Chemical compound C1=CC(N)=CC=C1CC1=CC=C(N)C=C1 YBRVSVVVWCFQMG-UHFFFAOYSA-N 0.000 claims description 2
- CQMIJLIXKMKFQW-UHFFFAOYSA-N 4-phenylbenzene-1,2,3,5-tetracarboxylic acid Chemical compound OC(=O)C1=C(C(O)=O)C(C(=O)O)=CC(C(O)=O)=C1C1=CC=CC=C1 CQMIJLIXKMKFQW-UHFFFAOYSA-N 0.000 claims description 2
- DKPFZGUDAPQIHT-UHFFFAOYSA-N Butyl acetate Natural products CCCCOC(C)=O DKPFZGUDAPQIHT-UHFFFAOYSA-N 0.000 claims description 2
- QOSSAOTZNIDXMA-UHFFFAOYSA-N Dicylcohexylcarbodiimide Chemical compound C1CCCCC1N=C=NC1CCCCC1 QOSSAOTZNIDXMA-UHFFFAOYSA-N 0.000 claims description 2
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 2
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 2
- 239000012965 benzophenone Substances 0.000 claims description 2
- FUZZWVXGSFPDMH-UHFFFAOYSA-N hexanoic acid Chemical compound CCCCCC(O)=O FUZZWVXGSFPDMH-UHFFFAOYSA-N 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 238000004321 preservation Methods 0.000 claims description 2
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 claims description 2
- 150000002148 esters Chemical class 0.000 claims 1
- 230000017525 heat dissipation Effects 0.000 description 10
- 238000012546 transfer Methods 0.000 description 8
- 235000012431 wafers Nutrition 0.000 description 8
- 238000003490 calendering Methods 0.000 description 7
- 239000000835 fiber Substances 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000004642 Polyimide Substances 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910021389 graphene Inorganic materials 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000002604 ultrasonography Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229920000742 Cotton Polymers 0.000 description 2
- 239000004952 Polyamide Substances 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- 238000010030 laminating Methods 0.000 description 2
- 238000010907 mechanical stirring Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229920002647 polyamide Polymers 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- VLDPXPPHXDGHEW-UHFFFAOYSA-N 1-chloro-2-dichlorophosphoryloxybenzene Chemical compound ClC1=CC=CC=C1OP(Cl)(Cl)=O VLDPXPPHXDGHEW-UHFFFAOYSA-N 0.000 description 1
- 235000017166 Bambusa arundinacea Nutrition 0.000 description 1
- 235000017491 Bambusa tulda Nutrition 0.000 description 1
- 240000006240 Linum usitatissimum Species 0.000 description 1
- 235000004431 Linum usitatissimum Nutrition 0.000 description 1
- 244000082204 Phyllostachys viridis Species 0.000 description 1
- 235000015334 Phyllostachys viridis Nutrition 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- 239000011425 bamboo Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- USIUVYZYUHIAEV-UHFFFAOYSA-N diphenyl ether Natural products C=1C=CC=CC=1OC1=CC=CC=C1 USIUVYZYUHIAEV-UHFFFAOYSA-N 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000000265 homogenisation Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000003760 magnetic stirring Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- GDOPTJXRTPNYNR-UHFFFAOYSA-N methyl-cyclopentane Natural products CC1CCCC1 GDOPTJXRTPNYNR-UHFFFAOYSA-N 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000002464 physical blending Methods 0.000 description 1
- 239000002798 polar solvent Substances 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 125000006158 tetracarboxylic acid group Chemical group 0.000 description 1
Images
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/28—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42
- B32B27/281—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42 comprising polyimides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
- B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
- B32B3/02—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by features of form at particular places, e.g. in edge regions
- B32B3/08—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by features of form at particular places, e.g. in edge regions characterised by added members at particular parts
- B32B3/085—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by features of form at particular places, e.g. in edge regions characterised by added members at particular parts spaced apart pieces on the surface of a layer
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B33/00—Layered products characterised by particular properties or particular surface features, e.g. particular surface coatings; Layered products designed for particular purposes not covered by another single class
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/15—Nano-sized carbon materials
- C01B32/18—Nanoonions; Nanoscrolls; Nanohorns; Nanocones; Nanowalls
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/30—Properties of the layers or laminate having particular thermal properties
- B32B2307/302—Conductive
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2457/00—Electrical equipment
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Abstract
The invention relates to a preparation method of an artificial graphite composite membrane, which comprises the following steps: dispersing cellulose nanocrystals in a solvent, sequentially adding an aromatic diamine monomer and an aromatic dianhydride monomer, and carrying out polycondensation reaction to obtain a cellulose nanocrystal modified polyamic acid mixture; carrying out chemical imidization treatment on the obtained polyamic acid mixture, removing partial solvent to obtain a gel film, and carrying out biaxial tension and high-temperature treatment to obtain a modified polyimide film; and (3) under an inert atmosphere, treating the obtained modified polyimide film, and graphitizing at a high temperature to obtain the artificial graphite composite film. The invention also provides an artificial graphite composite membrane.
Description
Technical Field
The invention relates to the field of film materials, in particular to an artificial graphite composite film and a preparation method thereof.
Background
With the rapid development of various electronic and electrical devices toward miniaturization, high power, light weight, and integration, the heat generated per unit volume will be significantly increased, and therefore, higher requirements are put on the heat dissipation performance of the devices, especially for 5G electronic communication devices. Compared with the commonly used metal-based or ceramic-based heat dissipation materials, the carbon-based heat dissipation material (such as natural graphite, graphene and carbon nano tubes) has the advantages of high heat conductivity coefficient, light density, low thermal expansion coefficient, good flexibility and the like, and can meet the heat dissipation requirements of future integrated electronic equipment, so that the heat dissipation material is widely researched.
Although the graphite heat dissipation film prepared from graphene or graphene oxide can achieve ultra-high heat conduction performance, the preparation method of the graphite heat dissipation film only stays in a laboratory stage, and the graphite heat dissipation film is difficult to adapt to industrial production. High heat conductivity graphite film (in current industrial production)>1000W·m-1·K-1) Mainly prepared by sintering polyimide at high temperature. Although the in-plane thermal conductivity coefficient of the polyimide-based graphite composite film can reach 1000 W.m-1·K-1Above, however, the thermal conductivity in the vertical direction is usually low, usually less than 5 W.m-1·K-1Therefore, heat is not easy to diffuse rapidly along the vertical direction, and the heat dissipation capability in practical use is greatly limited.
Disclosure of Invention
In view of this, the present invention provides an artificial graphite composite film having a high thermal conductivity in the vertical direction.
A preparation method of an artificial graphite composite membrane comprises the following steps:
dispersing cellulose nanocrystals in a solvent, sequentially adding an aromatic diamine monomer and an aromatic dianhydride monomer, and carrying out polycondensation reaction to obtain a cellulose nanocrystal modified polyamic acid mixture;
carrying out chemical imidization treatment on the obtained polyamic acid mixture, removing partial solvent to obtain a gel film, and carrying out biaxial tension and high-temperature treatment to obtain a modified polyimide film;
and (3) under an inert atmosphere, treating the obtained modified polyimide film, and graphitizing at a high temperature to obtain the artificial graphite composite film.
The present invention also provides an artificial graphite composite membrane comprising graphite wafer structures and rod-like crystalline carbon aggregates located between adjacent graphite wafer structures.
Compared with the prior art, the preparation method of the artificial graphite composite membrane has the advantages that the cellulose nanocrystals are added before the polycondensation reaction for synthesizing the polyamic acid, so that the cellulose nanocrystals can be uniformly dispersed in the polyamic acid and partially participate in the polycondensation reaction to form covalent bond connection with the polyamic acid, promote good interface combination between the cellulose nanocrystals and the polyamic acid, and further reduce interface phonon scattering. Finally, through carbonization and high-temperature graphitization treatment, the doped cellulose nanocrystals are converted into highly crystallized rod-shaped crystalline carbon which is distributed between adjacent graphite wafer structures in an aggregate form and is tightly combined with the graphite wafers, so that phonon scattering of heat transmitted along the vertical direction of the film can be obviously reduced, the heat conductivity coefficients of the film in the in-plane direction and the vertical direction are improved, and the heat conductivity coefficient in the vertical direction can reach 10 W.m-1·K-1The above. The artificial graphite composite membrane can play an excellent heat dissipation effect in future integrated and thin electronic equipment and the like, and has important application value.
The preparation method is simple to operate and easy to industrialize.
Drawings
Fig. 1 is a schematic view of the microstructure of the artificial graphite composite membrane according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of the present invention.
Referring to fig. 1, the present invention provides an artificial graphite composite membrane including a plurality of graphite wafer structures and rod-shaped crystalline carbon aggregates between the adjacent graphite wafer structures. The rod-shaped crystalline carbon may serve to improve the heat conductivity of the artificial graphite composite membrane in the vertical direction. Specifically, the artificial graphite composite membrane has a thermal conductivity in a direction perpendicular to the surface thereof>10W·m-1·K-1。
The invention also provides a preparation method of the artificial graphite composite membrane, which comprises the following steps:
s1, dispersing the cellulose nanocrystals in a solvent, sequentially adding an aromatic diamine monomer and an aromatic dianhydride monomer, and carrying out polycondensation reaction to obtain a polyamide acid mixture modified by the cellulose nanocrystals;
s2, performing chemical imidization treatment on the obtained polyamic acid mixture, removing partial solvent to obtain a gel film, and performing biaxial tension and high-temperature treatment to obtain a modified polyimide film; and
and S3, sequentially carrying out carbonization treatment and high-temperature graphitization treatment on the obtained modified polyimide film in an inert atmosphere to obtain the artificial graphite composite film.
The reason why the cellulose nanocrystals are dispersed in the solvent in advance in step S1 is: the surface of the cellulose nanocrystal is provided with polar functional groups such as hydroxyl, carboxyl or amino, and the like, and the functional groups can partially participate in the reaction in the polycondensation reaction to form covalent bond connection with polyamic acid, so that the cellulose nanocrystal and polyamic acid are firmly combined. Preferably, the functional group is at least one of a hydroxyl group, a carboxyl group and an amino group.
The source of the cellulose nanocrystal is not limited, and the cellulose nanocrystal can be prepared by a TEMPO oxidation method of a crude fiber raw material, comprises one or more of cotton fiber, bamboo fiber, microcrystalline fiber and flax fiber, and is preferably prepared by taking the microcrystalline fiber and the cotton fiber as raw materials. The cellulose nanocrystal is low in manufacturing cost and wide in source. Preferably, the crystallinity of the cellulose nanocrystal is more than 85%, the length is 100nm-200nm, and the diameter is 5nm-20 nm.
The method of dispersing the cellulose nanocrystals in the solvent may be physical blending means such as at least one of magnetic stirring, mechanical stirring, high-speed homogenization, water bath ultrasound, probe ultrasound.
The content of the cellulose nanocrystal in the polyamic acid mixture is 0.4-8.0%. Preferably, the cellulose nanocrystals are contained in the polyamic acid mixture in an amount of 1.0% to 5.0% considering that too little cellulose nanocrystal addition is insufficient to form a sufficiently effective connection between all graphite wafer structures, while excessive cellulose nanocrystal addition increases the spacing between adjacent graphite wafer structures and deteriorates mechanical properties.
The mass ratio of the cellulose nanocrystal to the sum of the aromatic diamine and the aromatic dianhydride monomer is 1 (1-49). Preferably, the mass ratio of the cellulose nanocrystal to the sum of the aromatic diamine and the aromatic dianhydride monomer is 1 (3-19) for the same reason as the above-mentioned preference of the cellulose nanocrystal.
The solvent is organic polar solvent, so that the raw materials can be uniformly dispersed, and specifically can be one of N-methylpyrrolidone, N-dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide and butyl acetate. The aromatic diamine monomer is one of 4,4 '-diaminodiphenyl ether, 1, 4-p-phenylenediamine, 3, 4' -diaminodiphenyl ether and 4, 4-diaminodiphenylmethane. The aromatic dianhydride monomer comprises one of 1,2,4, 5-pyromellitic dianhydride, 3 ', 4,4 ' -biphenyl tetracarboxylic dianhydride, 4,4 ' -benzophenone dianhydride and 3,3 ', 4,4 ' -diphenyl ether tetracarboxylic dianhydride. The molar ratio of the aromatic diamine monomer to the aromatic dianhydride monomer is 1:1-1: 1.05. The temperature of the polycondensation reaction is 2-25 ℃, and the time of the polycondensation reaction is 4-18 hours. In order to make the polyamic acid have a larger molecular weight, it is preferable that the molar ratio of the aromatic diamine monomer to the aromatic dianhydride monomer is 1:1 to 1:1.01, the temperature of the polycondensation reaction is 2 ℃ to 5 ℃, and the time of the polycondensation reaction is 6 hours to 8 hours.
It is noted that the aromatic dianhydride monomer is added last, and preferably slowly with mechanical agitation, so that the polycondensation reaction proceeds sufficiently.
In step S2, the step of chemically imidizing the polyamic acid mixture is specifically: and adding a dehydrating agent and a catalyst to the polyamic acid mixture, wherein the catalyst comprises at least one of triethylamine, pyridine, diethyl pyridine and isoquinoline, and the dehydrating agent comprises at least one of acetic anhydride, dicyclohexyl carbodiimide, benzoic anhydride and sodium tert-butoxide. The stretching process can be as follows: and (3) carrying out biaxial stretching at the temperature of 80-140 ℃, wherein the stretching ratio is 1.1-1.9 times, and preferably 1.1-1.5 times. Further, the membrane after biaxial stretching is respectively kept for 5min to 30min at the temperature of 120 ℃ to 200 ℃ and for 5min to 20min at the temperature of 200 ℃ to 350 ℃ under the protection of nitrogen and tension.
In this case, the thickness of the modified polyimide film obtained is 10 μm to 100. mu.m, preferably 30 μm to 100. mu.m.
In step S3, the carbonization process includes a first treatment process and a second treatment process, the first treatment process is performed by maintaining the temperature at 600 ℃ to 1000 ℃ for 0.5 hour to 1.5 hours, and the second treatment process is performed by maintaining the temperature at 1200 ℃ to 1600 ℃ for 0.5 hour to 1.5 hours. Preferably, the carbonization process includes a first treatment process of maintaining the temperature at 800-900 ℃ for 1-1.5 hours and a second treatment process of maintaining the temperature at 1500-1600 ℃ for 0.5-1 hour, considering that too low temperature or too little time may result in a low carbonization degree, and too high temperature or too long time may cause damage to the modified polyimide film.
The high-temperature graphitization process is that heat preservation is carried out for 0.5 to 1.5 hours at 2600 to 3000 ℃ under inert atmosphere. Preferably, the high temperature graphitization process is performed at 2800 deg.C-2850 deg.C for 0.5 hours to 1 hour under an inert atmosphere, considering that too low a temperature or too little time may result in a low graphitization degree of the carbonized film, while too high a temperature or too long a time may cause excessive energy loss or possible damage to the film.
Of course, in practice, the modified polyimide film may be processed by using additional graphite paper as a substrate during carbonization and high-temperature graphitization. The resulting artificial graphite composite membrane may, of course, be subjected to a further calendering step. The role of calendering is: eliminate the gas remained in the film during the sintering process, so that the film structure is more compact and uniform for better application.
The thickness of the artificial graphite composite membrane is 20-60 microns, preferably 20-40 microns.
Hereinafter, the artificial graphite composite membrane and the method for preparing the artificial graphite composite membrane according to the present invention will be described with reference to examples.
Example 1
(1) Adding a certain amount of cellulose nanocrystalline with carboxylated surfaces into N-methyl pyrrolidone, and uniformly dispersing the cellulose nanocrystalline in an organic solvent through water bath ultrasound. Adding 4, 4' -diaminodiphenyl ether into the solution, mechanically stirring to fully dissolve the solution, then reducing the temperature of the system to 5 ℃, gradually adding equal molar amount of pyromellitic dianhydride while stirring, reacting for 6 hours, so that the viscosity of the system is obviously increased, and obtaining a viscous polyamide acid mixture modified by the cellulose nanocrystal. Wherein the mass percentage of the cellulose nanocrystal in the polyamic acid mixture is 1.0%. Since the molar ratios of the aromatic diamine monomer and the aromatic dianhydride monomer are equal, it is assumed that the polycondensation reaction is complete and the polyamic acid mixture has a solids content of about 20 wt%.
(2) Adding acetic anhydride and pyridine to the cellulose nanocrystal-modified polyamic acid mixture obtained in step (1) with mechanical stirring. After being mixed evenly, the air bubbles in the solution are removed by multiple air exhaust and air release in a vacuum oven, and then the film is quickly formed on a flat and clean glass plate by casting. Heating the platform to 50-60 deg.C for 10-20min, and 80-100 deg.C for 10-20min, and volatilizing solvent to obtain non-sticky gel film. Further, the glass plate was peeled off, and the resultant was put into a biaxial stretching jig to be subjected to biaxial stretching treatment, with the stretching ratio being controlled to 1.4. And then placing the film into an oven under the action of tension, and keeping the film at 150 ℃ for 20min and 320 ℃ for 15min to obtain the modified polyimide film.
(3) Cutting the polyimide film doped with the cellulose nanocrystals into a proper size, crossly laminating the polyimide film with graphite paper, applying a certain pressure, putting the polyimide film into a carbonization furnace under the protection of argon, raising the temperature to 800 ℃ according to a program, keeping the temperature for 60min, keeping the temperature at 1500 ℃ for 40min, and then naturally cooling to room temperature to obtain the carbonized film.
(4) And (3) alternately laminating the obtained carbonized film and graphite paper, applying a certain pressure, putting the carbonized film and the graphite paper into a graphitization furnace under the protection of argon, raising the temperature to 2800 ℃ according to a program, keeping the temperature for 40min, naturally cooling the carbonized film to room temperature, and performing calendaring treatment to obtain the final rod-shaped crystal carbon composite artificial graphite composite film.
The in-plane and vertical heat conduction performance of the obtained artificial graphite composite film is tested by a laser flash method heat conduction tester LFA467 of Germany Chineseme corporation, and the test result is as follows: the in-plane and perpendicular thermal conductivities are shown in table 1. The following examples were also tested using this.
Example 2
The same parts of this example as those of example 1 are not repeated, and the difference from example 1 is that the mass percentage of the surface-carboxylated cellulose nanocrystal in the polyamic acid mixture in step (1) is 2.0%. The heat transfer properties of the finally obtained artificial graphite composite membrane are shown in table 1.
Example 3
The same parts of this example as those of example 1 are not repeated, and the difference from example 1 is that the mass percentage of the surface-carboxylated cellulose nanocrystal in the polyamic acid mixture in step (1) is 3.0%. The heat transfer properties of the finally obtained artificial graphite composite membrane are shown in table 1.
Example 4
The same parts of this example as those of example 1 are not repeated, and the difference from example 1 is that the mass percentage of the cellulose nanocrystal in the polyamic acid mixture in step (1) is 4.0%. The heat transfer properties of the finally obtained artificial graphite composite membrane are shown in table 1.
Example 5
The same parts of this example as those of example 1 are not repeated, and the difference from example 1 is that the mass percentage of the surface-carboxylated cellulose nanocrystal in the polyamic acid mixture in step (1) is 5.0%. The heat transfer properties of the finally obtained artificial graphite composite membrane are shown in table 1.
Example 6
The same parts of this example as those of example 1 are not repeated, and the difference from example 1 is that the mass percentage of the surface-carboxylated cellulose nanocrystal in the polyamic acid mixture in step (1) is 0.4%. The heat transfer properties of the finally obtained artificial graphite composite membrane are shown in table 1.
Example 7
The same parts of this example as those of example 1 are not repeated, and the difference from example 1 is that the mass percentage of the surface-carboxylated cellulose nanocrystal in the polyamic acid mixture in step (1) is 8.0%. The heat transfer properties of the finally obtained artificial graphite composite membrane are shown in table 1.
Example 8
The same parts of this embodiment as those of embodiment 2 are not repeated, and the difference from embodiment 2 is that the cellulose nanocrystal added in step (1) is a surface-hydroxylated cellulose nanocrystal. The heat transfer properties of the finally obtained artificial graphite composite membrane are shown in table 1.
Example 9
The same parts of this embodiment as those of embodiment 2 are not repeated, and the difference from embodiment 2 is that the cellulose nanocrystal added in step (1) is a surface aminated cellulose nanocrystal. The heat transfer properties of the finally obtained artificial graphite composite membrane are shown in table 1.
Example 10
The same parts of this example as those of example 2 are not repeated, and the difference from example 2 is that the cellulose nanocrystals added in step (1) are surface-esterified cellulose nanocrystals, and the heat conductivity of the finally obtained artificial graphite composite membrane is shown in table 1.
Example 11
The same parts as those in example 2 are not repeated, and the difference from example 2 is that the thickness of the artificial graphite composite film obtained after the calendering in step (4) is 20 μm, and the heat conductivity of the artificial graphite composite film finally obtained is shown in table 1.
Example 12
The same parts as those in example 2 are not repeated, and the difference from example 2 is that the thickness of the artificial graphite composite film obtained after the calendering in step (4) is 40 μm, and the heat conductivity of the artificial graphite composite film finally obtained is shown in table 1.
Example 13
The same parts of this example as those of example 2 are not repeated, and the difference from example 2 is that the thickness of the artificial graphite composite film obtained after the calendering in step (4) is 50 μm, and the heat conductivity of the finally obtained artificial graphite composite film is shown in table 1.
Example 14
The same parts of this example as those of example 2 are not repeated, and the difference from example 2 is that the thickness of the artificial graphite composite film obtained after the calendering in step (4) is 60 μm, and the heat conductivity of the finally obtained artificial graphite composite film is shown in table 1.
In order to better illustrate the advantageous effects of the artificial graphite composite membrane of the present invention, the present invention also provides comparative example 1.
Comparative example 1
The same parts of the comparative example and example 1 are not repeated, and the difference from example 1 is that the cellulose nanocrystals are not added in the step (1), and the heat conduction performance of the finally obtained artificial graphite composite membrane is shown in table 1.
TABLE 1
As can be seen from Table 1, comparing example 2 with examples 8-10, it can be seen that the different modification of the functionalized cellulose nanocrystals provided by the present invention have different enhancing effects on the obtained artificial graphite composite membrane, wherein the effects of carboxyl and hydroxyl are most prominentIt is presumed that the covalent bond is formed better and the bond is tighter with the polyimide. As can be seen from comparison of examples 1 to 7, the content of the cellulose nanocrystals in the polyamic acid mixture was in the range of 1.0 wt% to 5.0 wt%, and the resulting artificial graphite composite film was excellent in thermal conductivity. Comparing example 2 with examples 11 to 14, it can be seen that the artificial graphite composite membrane can realize an in-plane thermal conductivity of more than 1200 W.m in the thickness range of 20 μm to 60 μm-1·K-1And a thermal conductivity greater than 10 W.m in the vertical direction-1·K-1。
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (14)
1. The preparation method of the artificial graphite composite membrane is characterized by comprising the following steps of:
dispersing cellulose nanocrystals in a solvent, sequentially adding an aromatic diamine monomer and an aromatic dianhydride monomer, and carrying out polycondensation reaction to obtain a cellulose nanocrystal modified polyamic acid mixture;
carrying out chemical imidization treatment on the obtained polyamic acid mixture, removing partial solvent to obtain a gel film, and carrying out biaxial tension and high-temperature treatment to obtain a modified polyimide film; and
and sequentially carrying out carbonization treatment and high-temperature graphitization treatment on the obtained modified polyimide film in an inert atmosphere to obtain the artificial graphite composite film.
2. The method for preparing the artificial graphite composite membrane according to claim 1, wherein the surface of the cellulose nanocrystal has a functional group, and the functional group is at least one of hydroxyl, carboxyl, amino and ester.
3. The preparation method of the artificial graphite composite film according to claim 1, wherein the content of the cellulose nanocrystal in the polyamic acid mixture is 0.4% -8.0%, and the mass ratio of the cellulose nanocrystal to the sum of the aromatic diamine and the aromatic dianhydride monomer is 1 (1-49).
4. The method for preparing the artificial graphite composite membrane according to claim 3, wherein the solvent is one of N-methylpyrrolidone, N-dimethylformamide, N-dimethylacetamide, dimethylsulfoxide, and butyl acetate.
5. The method of preparing the artificial graphite composite film according to claim 1, wherein the aromatic diamine monomer is one of 4,4 ' -diaminodiphenyl ether, 1, 4-p-phenylenediamine, 3,4 ' -diaminodiphenyl ether and 4, 4-diaminodiphenylmethane, and the aromatic dianhydride monomer includes one of 1,2,4, 5-pyromellitic dianhydride, 3 ', 4,4 ' -biphenyltetracarboxylic dianhydride, 4,4 ' -benzophenone dianhydride and 3,3 ', 4,4 ' -diphenylethertetracarboxylic dianhydride.
6. The method for preparing the artificial graphite composite membrane according to claim 1, wherein the molar ratio of the aromatic diamine monomer to the aromatic dianhydride monomer is 1:1 to 1: 1.05.
7. The method for preparing the artificial graphite composite membrane according to claim 1, wherein the temperature of the polycondensation reaction is 2 ℃ to 25 ℃, and the time of the polycondensation reaction is 4 hours to 18 hours.
8. The method for preparing the artificial graphite composite membrane according to claim 1, wherein the carbonization process comprises a first treatment process and a second treatment process, the first treatment process is performed by keeping the temperature at 600-1000 ℃ for 0.5-1.5 hours, and the second treatment process is performed by keeping the temperature at 1200-1600 ℃ for 0.5-1.5 hours.
9. A method for preparing the artificial graphite composite membrane according to claim 1, wherein the thickness of the artificial graphite composite membrane is 20 to 60 μm.
10. The method for preparing the artificial graphite composite membrane according to claim 1, wherein the high temperature graphitization process is heat preservation at 2600 ℃ to 3000 ℃ for 0.5 hour to 1.5 hours under an inert atmosphere.
11. The method for preparing the artificial graphite composite membrane according to claim 1, wherein the chemical imidization treatment of the polyamic acid mixture comprises: and adding a dehydrating agent and a catalyst to the polyamic acid mixture, wherein the catalyst comprises at least one of triethylamine, pyridine, diethyl pyridine and isoquinoline, and the dehydrating agent comprises at least one of acetic anhydride, dicyclohexyl carbodiimide, benzoic anhydride and sodium tert-butoxide.
12. An artificial graphite composite membrane obtained by the production method according to any one of claims 1 to 11, wherein the artificial graphite composite membrane comprises graphite wafer structures and rod-like crystalline carbon aggregates located between adjacent graphite wafer structures.
13. The artificial graphite composite membrane according to claim 12, wherein the artificial graphite composite membrane has a thermal conductivity in a direction perpendicular to a surface thereof>10W·m-1·K-1。
14. Use of the artificial graphite composite membrane according to claim 12 in the field of heat conduction.
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| CN112266260A (en) * | 2020-10-21 | 2021-01-26 | 安徽国风塑业股份有限公司 | Preparation method of polyimide graphite film |
| CN114524432A (en) * | 2022-02-09 | 2022-05-24 | 蜂巢能源科技股份有限公司 | Lithium ion battery cathode material, preparation method thereof and lithium ion battery |
| CN114736019A (en) * | 2022-06-10 | 2022-07-12 | 宁波长阳科技股份有限公司 | Artificial graphite sheet with high vertical heat conduction and radiating fin comprising artificial graphite sheet |
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| GB2421506B (en) * | 2003-05-22 | 2008-07-09 | Zyvex Corp | Nanocomposites and methods thereto |
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| CN104342850A (en) * | 2013-08-08 | 2015-02-11 | 珠海市红旌发展有限公司 | Polyimide film containing nanocrystal cellulose and preparation method thereof |
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| CN114736019A (en) * | 2022-06-10 | 2022-07-12 | 宁波长阳科技股份有限公司 | Artificial graphite sheet with high vertical heat conduction and radiating fin comprising artificial graphite sheet |
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