CN116144176B - Polyimide composition, film, preparation method and application thereof - Google Patents

Polyimide composition, film, preparation method and application thereof Download PDF

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CN116144176B
CN116144176B CN202310422392.XA CN202310422392A CN116144176B CN 116144176 B CN116144176 B CN 116144176B CN 202310422392 A CN202310422392 A CN 202310422392A CN 116144176 B CN116144176 B CN 116144176B
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polyimide
film
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CN116144176A (en
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杨振东
王汉利
王鹤
王云飞
杨月勇
徐志强
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Shandong Huaxia Shenzhou New Material Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L79/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen or carbon only, not provided for in groups C08L61/00 - C08L77/00
    • C08L79/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
    • C08L79/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/22—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion
    • B01D53/228—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion characterised by specific membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0006—Organic membrane manufacture by chemical reactions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/58—Other polymers having nitrogen in the main chain, with or without oxygen or carbon only
    • B01D71/62—Polycondensates having nitrogen-containing heterocyclic rings in the main chain
    • B01D71/64—Polyimides; Polyamide-imides; Polyester-imides; Polyamide acids or similar polyimide precursors
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/20—Halogens or halogen compounds
    • B01D2257/206—Organic halogen compounds
    • B01D2257/2066—Fluorine
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2379/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2361/00 - C08J2377/00
    • C08J2379/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
    • C08J2379/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2479/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2461/00 - C08J2477/00
    • C08J2479/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
    • C08J2479/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors

Abstract

The invention belongs to the technical field of functional polymer materials, and particularly relates to a polyimide composition, a film, a preparation method and application thereof. The polyimide composition disclosed by the invention consists of polyimide I and polyimide II in a weight ratio of 10:1-5, wherein the number average molecular weight of the polyimide I is 40000-150000 g/mol, and the number average molecular weight of the polyimide II is 1000-6000 g/mol. The polyimide gas separation membrane prepared from the polyimide composition has high selectivity and high permeability, and can efficiently separate R22/HFP gas, wherein the permeation coefficient of R22 is more than or equal to 40Barrer, and the selection coefficient of R22/HFP is more than or equal to 50. Meanwhile, the heat-resistant modified polypropylene composite material has good heat-resistant stability and excellent plasticizing resistance, so that the heat-resistant modified polypropylene composite material can be applied to recycling of fluorine-containing gas, waste of the fluorine-containing gas is reduced, and greenhouse effect is slowed down.

Description

Polyimide composition, film, preparation method and application thereof
Technical Field
The invention belongs to the technical field of functional polymer materials, and particularly relates to a polyimide composition, a film, a preparation method and application thereof.
Background
Polyimide (PI) has excellent thermal stability and chemical stability, adjustable structure, high mechanical strength, easy film forming property and better permeability and selectivity, is one of ideal gas separation membrane materials, and has been applied to separation of various gases, such as CO 2 /CH 4 、CO 2 /N 2 Etc., can be well separated using conventional polyimide.
However, conventional polyimide has low permeability to fluorine-containing gas, thereby decreasing separation efficiency. The patent KR1020170068827A, CN1830929A, CN107837654a reports a separation method of a common gas and a fluorine-containing gas, but the membrane used in the separation method has high permeation rate to the common gas, but extremely low permeation rate to the fluorine-containing gas, and when the two separated gases are both fluorine-containing gases, the separation efficiency is seriously affected, so that the separation purpose cannot be realized. And because the boiling point of the fluorine-containing gas is higher than that of the conventional gas, the fluorine-containing gas has higher congeability and plasticizing effect on the polyimide film. Therefore, when separating such gases, not only the permeability of the polyimide film to one of the fluorine-containing gases is improved, but also the selective permeability of the fluorine-containing gases is ensured, and at the same time, the plasticizing resistance of the polyimide is also ensured.
JP2016538351A discloses a self-crosslinking film formation by using a polyimide containing a carboxyl group or a polyaminodiamine in the synthesis of a polyimide. Although the obtained self-crosslinking polyimide film has better separation performance and plasticizing resistance, the molecular weight of the prepared polyimide is low due to the influence of low reactivity and the like of the polyaminodiamine, so that the prepared film has poorer mechanical property and gas permeability. Chinese patent document CN114395127a discloses a polyimide resin for separating fluorine-containing gas and a method for producing the same, and the polyimide gas separation membrane produced by the patent has both high selectivity and high permeability, and is capable of separating fluorine-containing gases R32 (difluoromethane) and R134a (1, 2-tetrafluoroethane). Although this patent solves the problems of permeability and plasticization of fluorine-containing gases R32 and R134a, it is difficult to combine the separation of different fluorine-containing gases due to the particularity of the fluorine-containing gases, and it is difficult for the polyimide gas separation membrane to achieve high separation efficiency for R22 (difluoromethane) and HFP (hexafluoropropylene).
Chinese patent document CN105555838A discloses a self-crosslinkable and self-crosslinked aromatic polyimide membrane for separation, which is mainly used for air purification, gas separation in natural gas, etc., and the separated gas is mostly oxygen, nitrogen, methane, etc. with smaller molecular size. However, the aromatic polyimide polymer contains side groups of carboxyl and hydroxyl in the same structure, the chain spacing of the formed crosslinked network structure is reduced due to the crosslinked structure, and the molecular diameter size of R22 and HFP is large, so that the aromatic polyimide polymer has low permeability to R22 and HFP, and high separation efficiency is difficult to realize.
Disclosure of Invention
The invention provides a polyimide composition, a polyimide film, a preparation method and application thereof, and aims to solve the problem that the existing polyimide film cannot efficiently separate R22 and HFP.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the polyimide composition is characterized by comprising polyimide I and polyimide II, wherein the weight ratio of the polyimide I to the polyimide II is 10:1-5;
the number average molecular weight of the polyimide I is 40000-150000 g/mol, and the number average molecular weight of the polyimide II is 1000-6000 g/mol;
the structural general formula of the polyimide I is shown as formula (1):
，
the number of repeating units m of the polyimide resin I of the formula (1) 1 And m 2 ，m 1 +m 2 Is a positive integer of 100 to 200, m 1 、m 2 Respectively are integers greater than or equal to 0;
the polyimide II has a structural general formula shown in a formula (2):
。
the polyimide II resin has a repeating unit number n of 5 to 20.
Wherein Ar is 1 、Ar 2 、Ar 3 Each independently selected from one of the following structures, and Ar 1 With Ar 2 The same or different:
、/>、/>、、/>、/>etc.
R 2 The structure is as follows:
x is selected from C 1 ~C 5 Is a hydrocarbon group; y is selected from->（-COOH）、（-COCl）、/>(-COBr), etc.
R 1 、R 3 Respectively selected from one of the following structures:
、/>、/>、/>、、/>、、/>、/>、、/>etc.
R 4 Is any one of the following structures:
、/>、、/>、/>、、/>etc.
Preferably, in the composition, the number average molecular weight of polyimide I is 45000-100000 g/mol, and the number average molecular weight of polyimide II is 1000-5000 g/mol.
Preferably Ar 1 、Ar 2 、Ar 3 Each independently selected from one of the following structures:
、/>、/>、、/>、/>；
R 1 、R 3 respectively selected from one of the following structures:
、/>、/>、、/>；
R 4 selected from the following structures:
、/>、/>、。
further preferably Ar 1 Is thatOr->；Ar 2 Is that、/>Or->；Ar 3 Is that、/>、/>；
R 1 Is thatOr->；
R 3 Is that、/>、/>。
Further preferably, m 2 Is not 0, ar 1 With Ar 2 The same applies. In polyimide I, ar 1 -R 1 The molar percentage of the structural units is 0-50%, preferably 0-30%.
Most preferably, the weight ratio of polyimide I to polyimide II in the composition is 10:1; the number average molecular weight of the polyimide I is 90000-100000 g/mol, and the number average molecular weight of the polyimide II is 1000-1500 g/mol; ar (Ar) 1 、Ar 2 Is that，R 1 Is->，R 2 Is->，Ar 3 Is that，R 3 Is->，R 4 Is->。
The invention also provides application of the composition in separating fluorine-containing gas.
The invention also provides application of the composition in separating difluoromethane and hexafluoropropylene.
The invention also provides a polymer based on the polyimide composition, which is obtained by crosslinking polyimide I and polyimide II.
The invention also provides a cross-linked polyimide film based on the polyimide composition, which comprises a polymer obtained by cross-linking polyimide I and polyimide II.
Preferably, the thickness of the crosslinked polyimide film is 75-150 μm, and the film thickness is controlled by the addition amount of the solution. The glass transition temperature of the crosslinked polyimide film is more than 300 ℃, preferably 310-360 ℃.
The invention also provides a method for preparing the crosslinked polyimide film, which comprises the following steps:
dissolving the polyimide composition into an organic solvent to obtain a polyimide composition uniform solution with certain solid content, and forming a film to obtain an initial polyimide composition film; then post-treating under nitrogen atmosphere to obtain the cross-linked polyimide film.
Preferably, the initial polyimide composition film is prepared by a cast film-forming process.
Preferably, the composition solution is filtered and vacuum defoamed prior to film formation.
Preferably, the organic solvent in the method for preparing the cross-linked polyimide film is at least one of N, N-Dimethylformamide (DMF), N-dimethylacetamide (DMAc) or N-methylpyrrolidone (NMP); the solid content is 10-30%; the drying temperature of the film forming is 80-120 ℃ and the drying time is 8-24 h; the post-treatment temperature is 250-350 ℃, and the post-treatment time is 10-60 minutes.
The invention also provides application of the cross-linked polyimide film in separating fluorine-containing gas, and the preferable fluorine-containing gas is difluoro-chloromethane and hexafluoropropylene. The permeability coefficient for R22 is greater than 40Barrer, preferably greater than 60Barrer, at 25 ℃,0.2 MPa; the selection coefficient for R22/HFP is greater than 50; the plasticizing pressure is more than 0.6MPa. Most preferably, the permeability coefficient of the crosslinked polyimide film to R22 is 79-80 Barrer at 25 ℃ and 0.2MPa, and the separation coefficient is 60-65.
According to the invention, different polyimide containing special functional groups is combined to obtain a polyimide composition with good compatibility and stability in the same solvent, and a cross-linked network structure obtained by heating and cross-linking a high-molecular polyimide I containing side group functional groups and a low-molecular polyimide II containing end group functional groups is realized, so that the hole size of the network structure is between 4.8 and 5.3, the obtained high permeability of R22 and high selectivity of R22/HFP are realized, the limitation of a trade-off effect is broken through, and the membrane separation efficiency is improved.
The beneficial effects of the invention are that
Compared with the prior art, the invention has the following beneficial effects:
1. the polyimide gas separation membrane prepared from the polyimide composition has high selectivity and high permeability, and can efficiently separate R22/HFP gas, wherein the permeation coefficient of R22 is more than or equal to 40Barrer, and the selection coefficient of R22/HFP is more than or equal to 50. Meanwhile, the glass has good heat-resistant stability, the glass transition temperature is higher than 300 ℃, the excellent plasticizing resistance is achieved, and the plasticizing pressure is higher than 0.6MPa.
2. The preparation method of the invention is scientific, reasonable, simple and easy to implement, and the existing polyimide separation membrane is mostly added with a small molecular cross-linking agent in the preparation process, and the small molecular cross-linking agent can influence the usability of the membrane. The method can solve the problem of film defect caused by removing the small molecular cross-linking agent used in the traditional cross-linking method.
3. The polyimide gas separation membrane is used for separating fluorine-containing gas, can reduce the emission of the fluorine-containing gas and slow down the greenhouse effect.
Drawings
FIG. 1 is a GPC chart of polyimide I in example 1.
FIG. 2 is an FT-IR chart of polyimide I in example 1.
Detailed Description
The preparation method of the polyimide resin I in the polyimide composition of the specific embodiment of the invention comprises the following steps:
under the protection of nitrogen, diamine is completely dissolved in an organic solvent, dianhydride is added to form a homogeneous solution, a catalyst and a dehydrating agent are added to continuously react for 5-18 hours at the temperature of 5-210 ℃, and the obtained reaction product is solidified and molded in a precipitant to obtain polyimide resin I.
The diamine comprises at least R 2 Diamines of the type, may also include R 1 A type diamine; the dianhydride comprises at least Ar 2 Type dianhydride, may also include Ar 1 And (3) a type dianhydride.
The Ar is as follows 1 Dianhydride and Ar 2 The dianhydride is one of 4,4'- (hexafluoroisopropyl) diphthalic anhydride (6 FDA), 2,3',3,4 '-biphenyl tetracarboxylic dianhydride (3, 4' -BPDA), 3', 4' -Benzophenone Tetracarboxylic Dianhydride (BTDA) and the like.
The R is 1 The diamine is selected from 2, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (6 FAP), 2-bis (3-amino-4-hydroxyphenyl) propane (BAP), 3-dihydroxybenzidine (HAB), 2,3 '-bis (trifluoromethyl) -4,4' -diaminobiphenyl (TFMB), 3, 5-diaminophenylacetic acid (DAPA), 3, 5-diaminophenylacetyl chloride (DAPC), 3, 5-diaminophenylacetyl bromide (DAPB), 3, 5-diaminobenzoic acid (DABA) and the like; r is R 2 The diamine is selected from 3, 5-diaminophenylacetic acid (DAPA), 3, 5-diaminophenylacetyl chloride (DAPC), 3, 5-diaminophenylacetyl bromide (DAPB), 3, 5-diaminobenzoic acid (DABA), etc.
In the preparation method of the polyimide resin I, the molar ratio of dianhydride to diamine is 1.0-1.05:1. Preferably Ar 2 Dianhydride, R in diamine 1 The diamine accounts for 0-50% of the diamine by mole, preferably 0-30%.
The organic solvent is at least one of N, N-Dimethylformamide (DMF), N-dimethylacetamide (DMAc) or N-methylpyrrolidone (NMP); the solid content of the homogeneous solution is 15-40 wt%, and the non-volatile matters in the homogeneous solution are dianhydride and diamine.
The catalyst is one of triethylamine, isoquinoline or pyridine, and the molar ratio of the catalyst to dianhydride is 0.01-5:1; the dehydrating agent is one of acetic anhydride, toluene or dimethylbenzene, and the molar ratio of the dehydrating agent to the catalyst is 1-20:1; the precipitant is at least one of pure water, ethanol or methanol.
Washing and drying the cured and formed product, wherein the washing is performed by using pure water, ethanol or methanol, and the drying conditions are as follows: the temperature is 80-150 ℃ and the time is 24-48 h.
The invention also provides a preparation method of polyimide resin II in the polyimide composition, which comprises the following steps: under the protection of nitrogen, R is as follows 3 Dissolving diamine in organic solvent completely, adding Ar 3 Adding a blocking agent after reacting for a period of time, continuously reacting for a period of time to form a homogeneous solution, and finally adding a catalyst and a dehydrating agent, and continuously reacting for a certain period of time to obtain a polyimide solution; pouring into a precipitator for solidification and molding, washing and drying to obtain polyimide resin II.
The Ar is as follows 3 The dianhydride is one of pyromellitic dianhydride (PMDA), 2,3,6, 7-naphthalene tetracarboxylic dianhydride (2, 3,6, 7-NTDA), 1,4,5, 8-naphthalene tetracarboxylic anhydride (1, 4,5, 8-NTDA) and the like. The R is 3 The diamine is selected from 2,4, 6-trimethyl-1, 3-phenylenediamine (TMPDA), 2,3,5, 6-tetramethyl-p-phenylenediamine (Durene), 4' -diaminodiphenyl ether (ODA), etc.
Ar in preparation method of polyimide resin II 3 Dianhydride and R 3 The molar ratio of the diamine is 1.2-2:1. The organic solvent is at least one of N, N-Dimethylformamide (DMF), N-dimethylacetamide (DMAc) or N-methylpyrrolidone (NMP). The solid content of the homogeneous solution is 5-10wt%.
The end capping agent is one of 3, 3-dihydroxybenzidine (HAB), 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (6 FAP), 2-bis (3-amino-4-hydroxyphenyl) propane (BAP), p-aminophenol (PAPO) and 4- (4, 5-dihydro-2-oxazolyl) aniline (DHOA). The usage amount of the end capping agent is 15-40% (mole fraction).
The catalyst is one of triethylamine, isoquinoline or pyridine, and the catalyst is Ar 3 The molar ratio of the dianhydride is 0.01-5:1, preferably 0.5-5:1; the dehydrating agent is one of acetic anhydride, toluene or xylene, and the molar ratio of the dehydrating agent to the catalyst is 1-20:1, preferably 1-10:1; the reaction temperature is 5-210 ℃ and the reaction time is 5-18 h; the precipitant is pure water, ethanol or methanolOne less.
The invention is further illustrated by the following examples, in which the raw materials are commercially available, except for the specific descriptions.
Example 1
Preparation of polyimide I (6 FDA-DAPA): in a four-necked flask equipped with mechanical stirring, a thermometer and a nitrogen inlet, 16.62g of 3, 5-diaminophenylacetic acid (DAPA) and 358.49 g of N, N-Dimethylformamide (DMF) were charged, and stirred under nitrogen until all dissolved. 46.65g of 4,4' - (hexafluoroisopropyl) diphthalic anhydride (6 FDA) was added at 5℃to give a homogeneous solution with 15% solids. 50.65g g triethylamine and 51.10g acetic anhydride were mixed and added to the homogeneous solution, and the temperature was kept at 5℃to continue the reaction for 18 hours to obtain a polyimide solution. Precipitating with pure water, collecting solid material, washing with pure water for several times, filtering, and oven drying to obtain polyimide resin I (6 FDA-DAPA) with 97% yield and 6.1X10-number average molecular weight 4 g/mol。
As can be seen from FIG. 1, polyimide I has a number average molecular weight of 61271 and a molecular weight distribution of 1.52. As can be seen from FIG. 2, 1720cm -1 And 1785cm -1 Symmetrical stretching vibration peak and asymmetrical stretching vibration peak with C=O respectively, 1600cm -1 A C=O stretching vibration peak of 718cm -1 Symmetrical stretching vibration peak of C-N, 1351cm -1 An asymmetric stretching vibration peak of C-N of 1250cm -1 、964cm -1 Is the bending vibration peak of O-H.
Preparation of polyimide II (PMDA-Durene/HAB): in a four-necked flask equipped with mechanical stirring, a thermometer and a nitrogen inlet, 3.29g of 2,3,5, 6-tetramethyl-p-phenylenediamine (Durene) and 206.16g of N, N-Dimethylformamide (DMF) are added, the mixture is stirred under the protection of nitrogen until the mixture is completely dissolved, 5.23g of pyromellitic dianhydride (PMDA) is added at 5 ℃, after 2 hours of reaction, 3-dihydroxybenzidine (HAB) serving as a blocking agent is added, after 4 hours of continuous reaction, a homogeneous solution with 5 percent of solid content is obtained, 12.15g of triethylamine and 12.26g of acetic anhydride are mixed and then added into the homogeneous solution, the temperature is kept at 5 ℃ and the reaction is continued for 18 hours, thus obtaining polyimideA solution. Precipitating with pure water, collecting solid material, washing with pure water for several times, filtering, and oven drying to obtain polyimide resin II (PMDA-Durene/HAB) with 95% yield and 2.7X10 number average molecular weight 3 g/mol。
Polyimide I (6 FDA-DAPA) and polyimide II (PMDA-Durene/HAB) prepared in example 1 were dissolved in N, N-Dimethylformamide (DMF) at a weight ratio of 10:4 to prepare a polyimide composition solution having a solids content of 20%. Then mechanically stirring to make the composition solution uniform, filtering and vacuum defoaming, pouring into a super flat culture dish, drying at 80 ℃ under air atmosphere for 24 hours to obtain an initial polyimide composition film, and then performing post-treatment in a muffle furnace at 350 ℃ under nitrogen atmosphere for 10 minutes to obtain the cross-linked polyimide gas separation membrane with the thickness of 75 mu m.
The glass transition temperature of the crosslinked polyimide separation membrane is 350.24 ℃; the gas permeability coefficient for R22 was 70.6Barrer and the separation coefficient for R22/HFP was 50.9 at 25℃and 0.2 MPa.
Example 2
Preparation steps of polyimide I (6 FDA-DAPA/6 FAP): into a four-necked flask equipped with mechanical stirring, a thermometer and a nitrogen inlet, 14.96g of 3, 5-diaminophenylacetic acid (DAPA), 3.66g of 2, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (6 FAP) and 261.06 g of N-methylpyrrolidone (NMP) were charged, and stirred under nitrogen until all dissolved, and 46.65g was charged at 30 ℃.4,4' - (hexafluoroisopropyl) diphthalic anhydride (6 FDA) gave a homogeneous solution with 20% solids. 7.91g of pyridine and 92.14g of toluene were mixed and added to the homogeneous solution, and the reaction was continued at 210℃for 5 hours to obtain a polyimide solution I. Precipitating with mixed solution of pure water and ethanol, collecting solid material, washing with pure water for several times, filtering, and oven drying to obtain polyimide resin I with 96% yield and 9.5X10 number average molecular weight 4 g/mol. Polyimide II (PMDA-Durene/DHOA) preparation procedure: into a four-necked flask equipped with mechanical stirring, a thermometer, a nitrogen inlet was charged 3.29g of 2,3,5, 6-tetramethylp-phenylenediamine (Durene) and124.41g N-methylpyrrolidone (NMP) was stirred under nitrogen until it was completely dissolved, 6.54g of pyromellitic dianhydride (PMDA) was added at 30℃and reacted for 2 hours, then 4- (4, 5-dihydro-2-oxazolyl) aniline (DHOA) as a capping agent was added and the reaction was continued for 4 hours to give a homogeneous solution having a solid content of 10%, 1.19g of pyridine and 15.93g of xylene were mixed and then added to the homogeneous solution, and the temperature was kept at 210℃and the reaction was continued for 5 hours to give a polyimide solution. Precipitating with mixed solution of pure water and ethanol, collecting solid material, washing with pure water for several times, filtering, and oven drying to obtain polyimide resin II (PMDA-Durene/DHOA) with 90% yield and 1.4X10 number average molecular weight 3 g/mol。
A polyimide composition solution having a solids content of 10% was prepared by dissolving the high molecular weight polyimide I (6 FDA-DAPA/6 FAP) prepared in example 2 and the low molecular weight polyimide II (PMDA-Durene/DHOA) in a weight ratio of 10:1 into N, N-dimethylacetamide (DMAc). Then using mechanical stirring to make the composition solution become uniform, filtering and vacuum defoamating, pouring into a super flat culture dish, drying in 100 ℃ air atmosphere for 16 hours to obtain an initial polyimide composition film, and then performing post-treatment in a muffle furnace at 250 ℃ in nitrogen atmosphere for 60 minutes to obtain the crosslinked polyimide separation film with the thickness of 150 mu m.
The glass transition temperature of the crosslinked polyimide separation membrane is 319.81 ℃; the gas permeation coefficient for R22 was 79.6Barrer and the separation coefficient for R22/HFP was 64.8 at 25℃and 0.2 MPa.
Example 3
Polyimide i (BPDA-DAPC) preparation procedure: into a four-necked flask equipped with a mechanical stirrer, a thermometer and a nitrogen inlet, 18.46g of 3, 5-diaminophenylacetyl chloride (DAPC) and 279.68g of N, N-dimethylacetamide (DMAc) were added, the mixture was stirred under nitrogen until all of them dissolved, 30.89g of 2,3',3,4' -biphenyltetracarboxylic dianhydride (BPDA) was added at 30℃to obtain a homogeneous solution having a solid content of 15%, 50.65g of triethylamine and 51.10g of acetic anhydride were mixed and then added to the homogeneous solution, the temperature was maintained at 30℃and the reaction was continued for 18 hours to obtain a polyimide solution. PouringPrecipitating in a mixture of pure water and methanol, collecting solid material, washing with pure water for several times, filtering, and oven drying to obtain polyimide resin with 97% yield and 4.8X10 number average molecular weight 4 g/mol. Preparation procedure of polyimide II (2.3.6.7-NTDA-ODA/BAP): into a four-necked flask equipped with a mechanical stirrer, a thermometer and a nitrogen inlet, 4.00g of 2,4, 6-trimethyl-1, 3-phenylenediamine (TMPDA) and 172.95 g of N, N-dimethylacetamide (DMAc) were added, the mixture was stirred under nitrogen until all of them dissolved, 8.05 g of 2.3.6.7-naphthalene tetracarboxylic dianhydride (2.3.6.7-NTDA) was added at 50℃to react for 2 hours, 7.17 g of 2, 2-bis (3-amino-4-hydroxyphenyl) propane (BAP) as a capping agent was added to react for 4 hours to obtain a homogeneous solution having a solid content of 10%, 15.19g of triethylamine and 15.33g of acetic anhydride were mixed and then added to the homogeneous solution, and the temperature was kept at 50℃to react for 8 hours to obtain a polyimide solution. Precipitating with ethanol, collecting solid material, washing with ethanol for several times, filtering, and oven drying to obtain polyimide resin with 92% yield and number average molecular weight of 1.9X10 3 g/mol。
Polyimide I (BPDA-DAPC) prepared in example 3 and polyimide II (2.3.6.7-NTDA-ODA/BAP) were dissolved in N-methylpyrrolidone (NMP) in a weight ratio of 10:3 to prepare a polyimide composition solution having a solids content of 20%. Then using mechanical stirring to make the composition solution become uniform, filtering and vacuum defoamating, pouring into a super flat culture dish, drying under the air atmosphere of 120 ℃ for 8 hours to obtain an initial polyimide composition film, and then performing post-treatment in a muffle furnace of 300 ℃ under the nitrogen atmosphere for 30 minutes to obtain the cross-linked polyimide composition film with the thickness of 120 mu m.
The glass transition temperature of the crosslinked polyimide separation membrane was 310.67 ℃, the gas permeation coefficient for R22 was 64.8Barrer at 25 ℃ and 0.2MPa, and the separation coefficient for R22/HFP was 54.4.
Example 4
Preparation of polyimide I (BPDA-DAPC/BAP): 12.92g of 3, 5-diaminophenylacetyl chloride was introduced into a four-necked flask equipped with mechanical stirring, thermometer, nitrogen inletDAPC), 7.75g of 2, 2-bis (3-amino-4-hydroxyphenyl) propane (BAP) and 75.14g of n, n-dimethylformamide (DMAc) were stirred under nitrogen until all dissolved, 29.42g of 2,3',3,4' -biphenyltetracarboxylic dianhydride (BPDA) was added at 30 ℃ to obtain a homogeneous solution having a solid content of 40%, 0.13g of isoquinoline and 1.84g of toluene were mixed and added to the above homogeneous solution, and the temperature was maintained at 160 ℃ to continue the reaction for 10 hours to obtain a polyimide solution. Precipitating with ethanol and methanol, collecting solid material, washing with ethanol for several times, filtering, and oven drying to obtain polyimide resin with 96% yield and 7.3X10 number average molecular weight 4 g/mol。
Preparation of polyimide II (1, 4,5, 8-NTDA-TMPDA/PAPO): 3.00g of 2,4, 6-trimethyl-1, 3-phenylenediamine (TMPDA) and 343.84g N-methylpyrrolidone (NMP) are added into a four-neck flask provided with a mechanical stirring, a thermometer and a nitrogen inlet, the mixture is stirred under the protection of nitrogen until the mixture is completely dissolved, 10.73g of 1,4,5, 8-naphthalene tetracarboxylic dianhydride (1, 4,5, 8-NTDA) is added at 30 ℃, after 2 hours of reaction, 4.365g of p-aminophenol (PAPO) as a blocking agent is added, after 4 hours of continuous reaction, a homogeneous solution with 5 percent of solid content is obtained, 5.17g of isoquinoline and 18.43g of toluene are mixed and then added into the homogeneous solution, the temperature is kept at 210 ℃, and the reaction is continued for 10 hours, so as to obtain a polyimide solution. Precipitating with mixed solution of methanol and ethanol, collecting solid material, washing with ethanol for several times, filtering, and oven drying to obtain polyimide resin II (1, 4,5, 8-NTDA-TMPDA/PAPO) with 93% yield and 4.7X10 number average molecular weight 3 g/mol。
Polyimide composition solutions having a solids content of 20% were prepared by dissolving polyimide I (BPDA-DAPC/BAP) prepared in example 4 and polyimide II (1, 4,5, 8-NTDA-TMPDA/PAPO) in a weight ratio of 10:3 into N, N-dimethylacetamide (DMAc). Then using mechanical stirring to make the composition solution become uniform, filtering and vacuum defoamating, pouring into a super flat culture dish, drying at 100 ℃ under air atmosphere for 16 hours to obtain an initial polyimide composition film, and then performing post-treatment for 30 minutes in a muffle furnace at 300 ℃ under nitrogen atmosphere to obtain the crosslinked polyimide composition film with the thickness of 100 mu m.
The glass transition temperature of the crosslinked polyimide separation membrane was 330.66 ℃, the gas permeation coefficient for R22 was 42.5Barrer at 25 ℃ and 0.2MPa, and the separation coefficient for R22/HFP was 70.1.
Example 5
Preparation of polyimide I (BTDA-DAPB): into a four-necked flask equipped with a mechanical stirrer, a thermometer and a nitrogen inlet, 22.91g of 3, 5-diaminophenylacetyl bromide (DAPB) and 320.36 g of N, N-dimethylacetamide (DMAc) were added, and the mixture was stirred under nitrogen until all of them dissolved, 33.63g of 3,3', 4' -Benzophenone Tetracarboxylic Dianhydride (BTDA) was added at 30℃to obtain a homogeneous solution having a solid content of 15%, 50.65g of triethylamine and 51.10g of acetic anhydride were mixed and then added to the homogeneous solution, and the temperature was kept at 70℃to continue the reaction for 15 hours to obtain a polyimide solution. Precipitating with mixed solution of methanol and ethanol, collecting solid material, filtering with ethanol for several times, oven drying to obtain polyimide resin with 97% yield and number average molecular weight of 5.5X10 4 g/mol。
Polyimide II (1, 4,5, 8-NTDA-TMPDA/PAPO) was the same as in example 7.
A polyimide composition solution having a solid content of 30% was prepared by dissolving the high molecular weight polyimide I (BPDA-DAPB) prepared in example 5 and the low molecular weight polyimide II (1, 4,5, 8-NTDA-TMPDA/PAPO) in a weight ratio of 10:5 into N, N-Dimethylformamide (DMF). Then using mechanical stirring to make the composition solution become uniform, filtering and vacuum defoamating, pouring into a super flat culture dish, drying under 80 ℃ air atmosphere for 24 hours to obtain an initial polyimide composition film, and then performing post-treatment in a muffle furnace at 350 ℃ under nitrogen atmosphere for 10 minutes to obtain the cross-linked polyimide composition film with the thickness of 100 mu m.
The glass transition temperature of the crosslinked polyimide separation membrane was 320.33 ℃, the gas permeation coefficient for R22 was 68.2Barrer at 25 ℃ and 0.2MPa, and the separation coefficient for R22/HFP was 55.6.
Comparative example 1
Polyimide I (6 FDA-DAPA) in example 1 was dissolved in N, N-Dimethylformamide (DMF), a polyimide solution having a solid content of 10% was prepared, filtered and vacuum defoamed, poured into a superflat dish, dried in an air atmosphere at 80℃for 24 hours to obtain an initial polyimide film, and then post-treated in a muffle furnace at 350℃under nitrogen atmosphere for 10 minutes to obtain a polyimide film having a thickness of 75. Mu.m.
The glass transition temperature of the polyimide separation membrane was 305.6 ℃. The gas permeability coefficient for R22 was 10.6Barrer and the separation coefficient for R22/HFP was 64.9 at 25℃and 0.2 MPa.
Comparative example 2
Polyimide II (PMDA-Durene/HAB) prepared in example 1 was dissolved in N, N-dimethylacetamide (DMAc) to prepare a polyimide solution with a solid content of 10%, filtered and vacuum defoamed, poured into a super plate, dried under an air atmosphere at 80℃for 24 hours to obtain an initial polyimide film, and then post-treated in a muffle furnace at 350℃for 10 minutes under a nitrogen atmosphere to obtain a polyimide film with a thickness of 75. Mu.m. Because of the low molecular weight, the prepared polyimide film has poor mechanical properties and cannot be subjected to thermal performance and gas permeability tests.
Comparative example 3
Polyimide films were prepared and tested for performance by the method of example 5 in chinese patent document CN114395127a (202111638518.4), and the glass transition temperature of the polyimide separation film was 310.5 ℃. The gas permeation coefficient for R22 was 28.9Barrer and the separation coefficient for R22/HFP was 69.4 at 25℃and 0.2 MPa.
Comparative example 4
Polyimide films were prepared and tested for performance by the method of example 1 of chinese patent document CN105555838A (201480051190.8), and the glass transition temperature of the polyimide separation film was 285.5 ℃. The gas permeation coefficient for R22 was 3.4Barrer and the separation coefficient for R22/HFP was 69.1 at 25℃and 0.2 MPa.

Claims (10)

1. The use of a polyimide film for separating fluorine-containing gases, wherein the film is a cross-linked polyimide film based on a polyimide composition, the film comprising a polymer obtained by cross-linking polyimide i and polyimide ii;
the composition consists of polyimide I and polyimide II, wherein the weight ratio of the polyimide I to the polyimide II is 10:1-5;
the number average molecular weight of the polyimide I is 40000-150000 g/mol, and the number average molecular weight of the polyimide II is 1000-6000 g/mol;
the structural general formula of the polyimide I is shown as formula (1):
，
the number of repeating units m of the polyimide resin I of the formula (1) 1 And m 2 ，m 1 +m 2 Is a positive integer of 100 to 200, m 1 、m 2 Respectively are integers greater than or equal to 0; m is m 2 Ar in polyimide I, other than 0 1 -R 1 The mol percentage of the structural units is 0-30%;
the polyimide II has a structural general formula shown in a formula (2):
，
the polyimide II resin has a repeating unit number n, wherein n is an integer of 5 to 20;
wherein Ar is 1 、Ar 2 、Ar 3 Each independently selected from one of the following structures, and Ar 1 With Ar 2 The same or different:
、/>、/>、/>、、/>；
R 2 the structure is as follows:
x is selected from C 1 ~C 5 Is a hydrocarbon group; y is selected from->、/>、；
R 1 Selected from one of the following structures:
、/>、/>、/>、、/>、、/>、/>、、/>；
R 3 selected from one of the following structures:
、/>、/>、；
R 4 is any one of the following structures:
、/>、、/>、/>、、/>。
2. the use according to claim 1, wherein the number average molecular weight of polyimide i in the composition is 45000-100000 g/mol and the number average molecular weight of polyimide ii is 1000-5000 g/mol.
3. The use according to claim 1, wherein Ar 1 、Ar 2 、Ar 3 Each independently selected from one of the following structures:
、/>、/>、/>、/>、/>；
R 1 selected from one of the following structures:
、/>、/>、、/>；
R 3 selected from one of the following structures:
、/>、/>；
R 4 selected from the following structures:
、/>、/>、。
4. the use according to claim 1, wherein,
Ar 1 is thatOr->；
Ar 2 Is that、/>Or->；
Ar 3 Is that、/>、/>；
R 1 Is thatOr->；
R 3 Is that、/>、/>。
5. The use according to claim 1, wherein Ar 1 With Ar 2 The same applies.
6. The use according to claim 1, wherein the weight ratio of polyimide i to polyimide ii in the composition is 10:1; the number average molecular weight of the polyimide I is 90000-100000 g/mol, and the number average molecular weight of the polyimide II is 1000-1500 g/mol; ar (Ar) 1 、Ar 2 Is that，R 1 Is->，R 2 Is->，Ar 3 Is->，R 3 Is->，R 4 Is->。
7. The use according to claim 1, wherein the polyimide film has a thickness of 75 to 150 μm.
8. The use according to claim 1, wherein the polyimide film is prepared by a process comprising the steps of:
dissolving the composition into an organic solvent to obtain a polyimide composition uniform solution with a certain solid content, and forming a film to obtain an initial polyimide composition film; then post-treating under nitrogen atmosphere to obtain the cross-linked polyimide film.
9. The use according to claim 8, wherein the organic solvent is at least one of N, N-dimethylformamide, N-dimethylacetamide or N-methylpyrrolidone; the solid content is 10-30%; the post-treatment temperature is 250-350 ℃, and the post-treatment time is 10-60 minutes.
10. The use according to claim 8, characterized in that it is in the separation of difluoromethane and hexafluoropropylene.
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CN113845659A (en) * 2021-10-20 2021-12-28 天津理工大学 Network type polyimide resin with flexible side chain, preparation method thereof and application in gas separation
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US5647894A (en) * 1994-06-08 1997-07-15 Nitto Denko Corporation Gas separating composite membrane and process for producing the same
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