CN114989432B

CN114989432B - Polyimide, preparation method and application thereof, thermoplastic polyimide engineering plastic, and preparation method and application thereof

Info

Publication number: CN114989432B
Application number: CN202210804405.5A
Authority: CN
Inventors: 职欣心; 高艳爽; 杜萱哲; 任茜; 张燕; 杨昶旭; 王晓蕾; 刘金刚
Original assignee: China University of Geosciences Beijing
Current assignee: China University of Geosciences Beijing
Priority date: 2022-07-08
Filing date: 2022-07-08
Publication date: 2023-05-05
Anticipated expiration: 2042-07-08
Also published as: CN114989432A

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to polyimide, a preparation method and application thereof, thermoplastic polyimide engineering plastic, and a preparation method and application thereof. The polyimide provided by the invention adopts a semi-alicyclic structure, wherein the introduction of the non-conjugated alicyclic structure in the dianhydride monomer can effectively inhibit CT interaction in a PI molecular chain based on the low molecular density and low polarity of the polyimide, and reduce the absorption of charges to visible light in the transfer and transition processes, so that the optical transparency of the polyimide can be effectively improved; the conjugated double bond of the benzene ring structure in the diamine monomer reduces the free rotation of the molecular chain and increases the rigidity of the molecular chain, so that the polyimide has good heat-resistant stability, the flexible ether bond can endow the polyimide molecular chain segment with good flexibility, when external force acts, the coiled molecule can be straightened, the molecule returns to the original coiled state after the external force is removed, and the mechanical properties of polyimide such as bending, compression, stretching and the like are improved.

Description

Polyimide, preparation method and application thereof, thermoplastic polyimide engineering plastic, and preparation method and application thereof

Technical Field

The invention belongs to the technical field of high polymer materials, and particularly relates to polyimide, a preparation method and application thereof, thermoplastic polyimide engineering plastic, and a preparation method and application thereof.

Background

In recent years, polyimide (PI) engineering plastics have received a great deal of attention in high-tech fields such as aviation, aerospace, microelectronics and the like due to the characteristics of high temperature resistance level, excellent mechanical properties, self-lubrication and the like. PI engineering plastics can be broadly classified into Thermoplastic PI (TPI) materials and thermosetting PI materials according to their structural characteristics. Among them, TPI engineering plastics have been rapidly developed in recent years due to the traction required by emerging industries such as large airplanes, new energy automobiles, wind power, and the like. TPI engineering plastics have the high temperature resistance, high insulation and high mechanical properties of PI materials and the melt processability of conventional thermoplastic engineering plastics, so that the TPI engineering plastics can be widely used for manufacturing parts such as bearings, auxiliary bearing parts and the like in the high technical field.

The excellent combination of properties has led to the development of TPI engineering plastics over the last decades, and a variety of commercial products have been developed, including Sanjing Chemie, japan

And->

Series, sauter Arabic Sabic +.>

And->

Series, mitsubishi gas Co., japan +.>

Series, domestic Shanghai institute of synthetic resins +.>

Series and vinca kawasaki polyimide materials limited

Series, etc. Although TPI engineering plastics have been widely used in a number of high technical fields, few basic studies so far have focused on colorless or pale transparencies of TPI engineering plastics. This is mainly due to the fact that in order to achieve good melt flow properties, conventional TPI engineering plastics tend to have molecular structures designed to favor crystallization. For example, the number of the cells to be processed,

and->

The components are semi-crystalline TPI engineering plastics. The existence of the crystallization area causes the incident light to be scattered and refracted due to the existence of the crystallization, so that the transmittance of the TPI engineering plastic is obviously deteriorated. In addition, in order to maintain a good temperature resistance level, the conventional commercial TPI engineering plastics basically use a wholly aromatic molecular chain structure, and thus, a Charge Transfer (CT) effect between a diamine unit as an electron donor and a dianhydride unit as an electron acceptor is strong. This CT action occurs not only within the molecular chain of TPI, but also between the molecular chains. The charge will absorb visible light significantly during the transfer and transition processes, making the TPI appear darker in appearance.

In recent years, the rapid development of optical communication technology has been increasingly pressing the demand for engineering plastics which are light in weight, high in strength, high in temperature resistance, low in dielectric, light in color and high in transparency. Conventional optical plastics such as polymethyl methacrylate (PMMA), polystyrene (PS), polycarbonate (PC), and Cyclic Olefin Polymer (COP) cannot meet the above application requirements. TPI engineering plastics, which are known to be excellent in high temperature resistance, face a great challenge in terms of optical properties. Because of the inherent highly conjugated structural features and charge transfer effects of TPI materials, there are great technical difficulties in achieving colorless transparentization.

The research achievement obtained in the research field of colorless transparent PI (CPI) films at home and abroad in recent years provides a beneficial reference for the research of light-color TPI engineering plastics. For the PI film, the CT interaction in the PI molecular chain can be obviously reduced by introducing certain specific groups, such as trifluoromethyl, hexafluoroisopropyl, sulfonyl, alicyclic and other non-conjugated structures with high electronegativity and huge free volume into the PI molecular chain, so that the color of the PI product can be effectively improved. For TPI engineering plastics, the modification means still has higher theoretical guiding significance, but the influence of the specific structural characteristics of the TPI engineering plastics, including thickness, crystallization characteristics, manufacturing process and the like on the appearance and color of the products thereof needs to be comprehensively considered in the process of molecular design. Researchers have prepared TPI resins by copolymerizing the fluorine-containing dianhydride monomer 4,4' - (hexafluoroisopropylidene) diphthalic anhydride (6 FDA) with a fluorine-containing diamine monomer, such as 4,4' -diamino-2, 2' -bistrifluoromethyl biphenyl (TFDB), a conventional wholly aromatic diamine monomer, and the like, and have prepared molded sheets by a molding process. Optical photographs show that the introduction of fluorine-containing groups does not produce a significant improvement in the optical transparency of the TPI molded articles. The prepared TPI molded tablets exhibited a translucent appearance ranging from dark brown to amber. Researchers also prepared TPI resin from ether bond-containing dianhydride, 3', 4' -diphenyl ether tetracarboxylic dianhydride (ODPA) and fluorine-containing diamine 1, 4-bis [ (4-amino-2-trifluoromethyl) phenoxy ] benzene (6 FAPB), and prepared TPI thin-walled parts by injection molding technology. The TPI article still exhibits a darker color and a translucent appearance.

Disclosure of Invention

In view of the above, the present invention aims to provide a polyimide, a preparation method and an application thereof, a thermoplastic polyimide engineering plastic, a preparation method and an application thereof, and the polyimide provided by the present invention has good heat-resistant stability and good optical transparency.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides polyimide, which has a structure shown in a formula I:

in formula I, the X includes

And/or +.>

The Ar comprises

And/or +.>

0<n is less than or equal to 300 and n is an integer.

Preferably, the polyimide is

n＝192；

n＝207；/>

n=234 or

n＝271。

The invention also provides a preparation method of the polyimide, which comprises the following steps:

mixing an aromatic diamine monomer, a dianhydride monomer and an aprotic strongly polar solvent, and performing polycondensation reaction to obtain a polyamic acid solution;

mixing the polyamic acid solution, an entrainer and a tertiary amine catalyst, and performing dehydration cyclization reaction to obtain a soluble polyimide solution;

mixing the soluble polyimide solution with organic alcohol, and performing alcohol precipitation to obtain polyimide;

the aromatic diamine monomer comprises

And/or

The dianhydride monomer comprises

And/or +.>

Preferably, the molar ratio of the dianhydride monomer to the aromatic diamine monomer is (0.95-1.02): 1.02-0.95.

Preferably, the aprotic polar solvent comprises one or more of N-methylpyrrolidone, m-cresol, N-dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide and gamma-butyrolactone; the entrainer comprises one or more of benzene, toluene and cyclohexane; the tertiary amine catalyst comprises one or more of pyridine, isoquinoline and triethylamine.

Preferably, the temperature of the polycondensation reaction is 10-30 ℃ and the time is 1-30 h; the temperature of the dehydration cyclization reaction is 120-200 ℃ and the time is 1-30 h.

The invention also provides application of the polyimide prepared by the technical scheme or the preparation method of the polyimide in thermoplastic polyimide engineering plastics.

The invention also provides a thermoplastic polyimide engineering plastic, which comprises polyimide; the polyimide is prepared by the polyimide prepared by the technical scheme or the preparation method.

The invention also provides a preparation method of the thermoplastic polyimide engineering plastic, which comprises the following steps:

polyimide is dissolved in an organic solvent to obtain polyimide solution;

mixing the polyimide solution and the alcohol solution, and sequentially carrying out first crushing, filtering, washing and drying to obtain molding powder;

sequentially carrying out second crushing and screening on the molding powder to obtain superfine molding powder;

and solidifying the superfine molding powder to obtain the thermoplastic polyimide engineering plastic.

The invention also provides application of the thermoplastic polyimide engineering plastic prepared by the technical scheme or the preparation method of the technical scheme in the fields of packaging substrates, optical communication and optical component manufacturing.

The invention provides polyimide, which has a structure shown in a formula I:

in formula I, the X includes

And/or +.>

/>

The Ar comprises

And/or +.>

0<n is less than or equal to 300 and n is an integer.

The polyimide provided by the invention adopts a semi-alicyclic structure, wherein the introduction of the non-conjugated alicyclic structure in the dianhydride monomer can effectively inhibit the Charge Transfer (CT) interaction in a Polyimide (PI) molecular chain based on the low molecular density and low polarity, and reduce the absorption of charges to visible light in the transfer and transition processes, so that the optical transparency of the polyimide can be effectively improved; the conjugated double bond of the benzene ring structure contained in the diamine monomer makes the free rotation of the molecular chain smaller, and increases the rigidity of the molecular chain, so that the polyimide has good heat-resistant stability, in addition, the flexible ether bond can endow the polyimide molecular chain segment with good flexibility, when external force acts on the molecule, the curled molecule can be straightened, and after the external force is removed, the molecule is restored to the original curled state, so that the mechanical properties of the polyimide such as bending, compression, stretching and the like are all improved.

Drawings

FIG. 1 is an infrared spectrum of a polyimide engineering plastic molded sheet prepared in examples 1 to 4;

FIG. 2 is a TGA spectrum of the molded sheet of polyimide engineering plastic prepared in application examples 1 to 4;

FIG. 3 is a DSC chart of the polyimide engineering plastic molded sheets prepared in application examples 1 to 4;

FIG. 4 is an ultraviolet-visible spectrum of the polyimide engineering plastic molded sheets prepared in application examples 1 to 4.

Detailed Description

The invention provides polyimide, which has a structure shown in a formula I:

in formula I, the X includes

And/or +.>

The Ar comprises

And/or +.>

0<n is less than or equal to 300 and n is an integer.

When the X is

And->

In the process, the position arrangement of the two groups is not particularly limited, and any arrangement mode can be adopted.

In the present invention, n is preferably 100 to 300; the polyimide is preferably

n＝192；/>

n＝207；

n=234 or->

n＝271。/>

the aromatic diamine monomer comprises

And/or

The dianhydride monomer comprises

And/or +.>

The present invention is not limited to the specific source of the raw materials used, and may be commercially available products known to those skilled in the art, unless otherwise specified.

The invention mixes aromatic diamine monomer, dianhydride monomer and aprotic strong polar solvent for polycondensation reaction to obtain polyamic acid solution.

In the present invention, the aromatic diamine monomer comprises

(1, 3-bis (3-aminophenoxy) benzene) and/or +.>

(1, 3-bis (4-aminophenoxy) benzene), more preferably +.>

When the aromatic diamine monomer is +.>

In the process, the proportion of the two raw materials is not particularly limited, and the two raw materials can be mixed at random.

In the present invention, the dianhydride monomer comprises

(ccHPMDA) and/or

(ctHPMDA), preferably->

When dianhydride monomer is->

In the process, the proportion of the two raw materials is not particularly limited, and the two raw materials can be mixed at random. Wherein the molecular structure of 1S,2R,4S, 5R-hydrogenated pyromellitic dianhydride (ccHPMDA) is in a boat form, 4 carbonyl groups are in an exo configuration, namely all face to the outside, the stereo barrier during polymerization is large, and 1R,2S,4S, 5R-hydrogenated pyromellitic dianhydride (ctHPMDA) moleculesThe structure assumes a boat-like shape with 2 carbonyl groups in the-exo configuration, toward the outside, and 2 carbonyl groups in the-endo configuration, toward the inside, with relatively little steric hindrance in polymerization.

In the present invention, the molar ratio of the dianhydride monomer to the aromatic diamine monomer is preferably (0.95 to 1.02): 1.02 to 0.95, more preferably (0.98 to 1.01): 1.

In the present invention, the aprotic strongly polar solvent preferably includes one or more of N-methylpyrrolidone, m-cresol, N-dimethylformamide, N-dimethylacetamide, dimethylsulfoxide and γ -butyrolactone, more preferably γ -butyrolactone; when the aprotic polar solvent is the aprotic polar solvent, the mixture ratio of the aprotic polar solvents of different types is not particularly limited, and the aprotic polar solvent can be mixed at random; the ratio of the mass of the aromatic diamine monomer and the dianhydride monomer to the total mass of the aromatic diamine monomer, the dianhydride monomer and the aprotic highly polar solvent is preferably (10 to 30): 100, more preferably (15 to 30): 100.

In the invention, the mixing process of the aromatic diamine monomer, the dianhydride monomer and the aprotic polar solvent is preferably to dissolve the aromatic diamine monomer in the aprotic polar solvent under the protection of nitrogen, form a homogeneous solution under the condition of stirring, and then add the dianhydride monomer; the temperature of the stirring is preferably normal temperature; the stirring time is preferably 10min. The stirring speed is not particularly limited, and the stirring speed well known in the art is adopted to uniformly mix the materials.

In the present invention, the temperature of the polycondensation reaction is preferably 10 to 30 ℃, more preferably 15 to 25 ℃, and the time is preferably 1 to 30 hours, more preferably 1 to 10 hours; the polycondensation reaction is carried out under the protection of nitrogen.

After the polyamic acid solution is obtained, the polyamic acid solution, the entrainer and the tertiary amine catalyst are mixed, and a dehydration cyclization reaction is carried out to obtain the soluble polyimide solution.

In the present invention, the entrainer preferably includes one or more of benzene, toluene and cyclohexane, more preferably toluene; when the entrainer is the above-mentioned several kinds, the invention has no special limitation on the mixture ratio of different kinds of entrainers, and the entrainer can be mixed at random; the tertiary amine catalyst preferably comprises one or more of pyridine, isoquinoline and triethylamine, and more preferably isoquinoline; when the tertiary amine catalyst is the above-mentioned several kinds, the proportion of the tertiary amine catalyst of different kinds is not particularly limited, and any proportion can be used; the amount of the entrainer and the tertiary amine catalyst used in the present invention is not particularly limited, and the entrainer and the tertiary amine catalyst can be used in amounts well known in the art. In the embodiment of the invention, the mass ratio of the aromatic diamine monomer to the entrainer is preferably 29.234:150; the mass ratio of the aromatic diamine monomer to the tertiary amine catalyst is preferably 29.234:0.5. The mixing process of the polyamic acid solution, the entrainer and the tertiary amine catalyst is not particularly limited, and may be a mixing process well known in the art.

In the present invention, the temperature of the dehydrative ring closure reaction is preferably 120 to 200 ℃, more preferably 130 to 180 ℃, and the time is preferably 1 to 30 hours, more preferably 3 to 10 hours; the dehydrative ring closure reaction is preferably carried out under reflux conditions; the equipment used for the polycondensation reaction and the dehydrate cyclization reaction is preferably a 1000mL four-necked glass flask composed of a mechanical stirrer, a tetrafluoro stirring rod, a thermometer, a Dean-Stark trap and a dry nitrogen inlet and outlet.

In the embodiment of the invention, the dehydration cyclization reaction specifically comprises the following steps: heating to 130-140 ℃, maintaining reflux dehydration for 6h, continuously heating to 180 ℃, distilling out redundant entrainer by a water separator, replacing the water separator with a reflux condenser tube, maintaining constant temperature for continuous reaction for 3h, and naturally cooling to normal temperature.

After the soluble polyimide solution is obtained, the invention mixes the soluble polyimide solution and the organic alcohol, and carries out alcohol precipitation to obtain polyimide.

In the present invention, the organic alcohol is preferably ethanol.

After the alcohol precipitation is finished, the polyimide is obtained by separating, washing and drying the materials after the alcohol precipitation in sequence.

In the present invention, the separation process is preferably carried out by filtration after standing overnight; the filtering process is not particularly limited, and filtering processes well known in the art can be adopted; the washing is preferably performed with ethanol; the drying equipment is preferably a vacuum drying oven; the drying temperature is preferably 60 to 120 ℃, more preferably 60 to 90 ℃; the drying time is preferably 5 to 30 hours, more preferably 10 to 25 hours.

polyimide is dissolved in an organic solvent to obtain polyimide solution;

Polyimide is dissolved in an organic solvent to obtain a polyimide solution.

In the present invention, the organic solvent is preferably one or more of N-methylpyrrolidone (NMP), N-dimethylacetamide (DMAc), dimethylsulfoxide (DMSO) and N, N-Dimethylformamide (DMF), more preferably N, N-dimethylacetamide (DMAc); the ratio of the mass of the polyimide to the total mass of the polyimide and the organic solvent is preferably (1 to 20): 100, more preferably (5 to 10): 100. The process of dissolving the polyimide in the organic solvent is not particularly limited, and a dissolving process well known in the art may be adopted.

After the polyimide solution is obtained, the alcohol solution is preferably stirred at room temperature for 12 hours. The stirring rate of the present invention is not particularly limited, and may be determined as needed.

After the polyimide solution is obtained, the polyimide solution and the alcohol solution are mixed, and the first crushing, the filtering, the washing and the drying are sequentially carried out to obtain the molding powder.

In the present invention, the alcohol solution is preferably an aqueous ethanol solution; the mass concentration of the alcohol solution is preferably 50%; the mixing process of the polyimide solution and the alcohol solution is preferably to pour the polyimide solution into the alcohol solution; the first comminution apparatus is preferably a high speed pulverizer; the washing is preferably performed with ethanol; the drying equipment is preferably a vacuum drying oven; the drying temperature is preferably 60 to 120 ℃, more preferably 60 to 90 ℃; the drying time is preferably 5 to 25 hours, more preferably 10 to 15 hours. The filtering process is not particularly limited in the present invention, and a filtering process well known in the art may be used.

After the molding powder is obtained, the molding powder is subjected to secondary crushing and screening in sequence to obtain the superfine molding powder. In the present invention, the first pulverizing apparatus is preferably a high-speed pulverizer; the sieving is preferably performed using a 200 mesh screen.

After the superfine molding powder is obtained, the invention preferably fills the superfine molding powder into a mold and cures the superfine molding powder to obtain the thermoplastic polyimide engineering plastic.

In the invention, the mold is preferably a stainless steel mold, the specification and the size of the mold are not particularly limited, and the mold can be selected according to actual needs; in the embodiment of the invention, the die is 80X 60X 120mm in size ³ Is a rectangular stainless steel mold; the filling amount of the superfine molding powder is not particularly limited, and the filling amount is determined according to actual needs; the curing device is preferably a molding press; the curing temperature is preferably 230 to 300 ℃, more preferably 250 to 300 ℃; the curing time is preferably 1 to 5 hours, more preferably 1 to 3 hours. In the application example of the invention, the curing conditions are as follows: 1) Rise under contact pressureThe temperature is up to 250 ℃; 2) When the temperature is raised to 250 ℃, applying 1.5MPa pressure, then raising the temperature to 300 ℃, and keeping the temperature for 1h under 2.0MPa pressure; 3) Naturally cooling to below 100deg.C, releasing the applied pressure, and opening the mold.

In the present invention, the optical communication field preferably includes optical waveguide and infrared signal transmission; the optics field preferably includes an optical lens, lens or image sensor. In addition, the portable mobile communication equipment parts applying the optical components of the thermoplastic polyimide engineering plastics disclosed by the invention also belong to the protection scope of the invention.

The application mode of the thermoplastic polyimide engineering plastic in the packaging substrate is not particularly limited, and the application mode well known in the art can be adopted.

The technical solutions of the present invention will be clearly and completely described in the following in connection with the embodiments of the present invention.

Example 1

Setting up a 1000mL four-necked glass flask consisting of a mechanical stirrer, a tetrafluoro stirring rod, a thermometer, a Dean-Stark water separator and a dry nitrogen inlet and outlet in a clean room, adding 120.0g of gamma-butyrolactone (GBL), introducing nitrogen, then adding 1, 3-bis (3-aminophenoxy) benzene 133APB (29.234 g,0.1 mol), stirring at normal temperature for 10min under the protection of nitrogen to obtain a homogeneous solution, adding 1S,2R,4S, 5R-hydrogenated pyromellitic dianhydride (ccHPMDA) (22.4170 g,0.1 mol) into the homogeneous solution, simultaneously adding 35.0g of gamma-butyrolactone (GBL), and carrying out polycondensation reaction at 25:100 ℃ by the mass ratio of 1, 3-bis (3-aminophenoxy) benzene to 1S,2R,4S, 5R-hydrogenated pyromellitic dianhydride to the total mass of 1, 3-bis (3-aminophenoxy) benzene, 1S,2R, 5R-hydrogenated pyromellitic dianhydride and gamma-butyrolactone, and stirring for 3h under the condition of 25 ℃; 150g of toluene and 0.5g of isoquinoline are added into the polyamic acid solution, the temperature is raised to 130 ℃, the azeotropic mixture of toluene and water is distilled out in the reaction system, the reflux dehydration is maintained for 6 hours until no water is distilled out in the water separator, the temperature is raised to 180 ℃ continuously, the excessive toluene is distilled out through the water separator, the water separator is replaced by a reflux condenser tube, the constant temperature is maintained for continuous reaction for 3 hours, the temperature is naturally lowered to normal temperature, the obtained pale yellow viscous solution is slowly poured into the excessive alcohol solution (75 vol%) to obtain pale yellow filiform sediment, the resin obtained after standing overnight is filtered and collected, the resin is fully washed by ethanol, and the filiform polyimide is obtained after vacuum drying for 24 hours at 80 ℃. The polyimide structure is as follows:

n＝192。

example 2

The difference from example 1 is that 1, 3-bis (3-aminophenoxy) benzene (133 APB) was replaced with 1, 3-bis (4-aminophenoxy) benzene (134 APB), and the remainder was identical to example 1, the polyimide having the structure shown below:

n＝207。

example 3

The difference from example 1 is that 1S,2R,4S, 5R-hydrogenated pyromellitic dianhydride (ccHPMDA) was replaced with 1R,2S,4S, 5R-hydrogenated pyromellitic dianhydride (ctHPMDA), and the rest was the same as in example 1, and the structure of the polyimide was as follows:

n＝234。

example 4

The difference from example 3 is that 1, 3-bis (3-aminophenoxy) benzene (133 APB) was replaced with 1, 3-bis (4-aminophenoxy) benzene (134 APB), and the remainder was identical to example 3, the polyimide having the structure shown below:

n＝271。

comparative example 1

Prepared by Shanghai institute of synthetic resins

YS-20 resin is polymerized by 3,3', 4' -diphenyl ether tetracarboxylic dianhydride (ODPA) and 4,4' -diaminodiphenyl ether (ODA).

Comparative example 2

Manufactured by Mitsui chemical Co., ltd

PL450C resin comprising pyromellitic dianhydride (PMDA) and 4,4' -bis [4- (3-aminophenoxy)]Biphenyl (BAPB) is polymerized.

Application example 1

A500 mL three-necked flask was charged with dried 10.0g of the polyimide prepared in example 1 and 190g of ultra-dry dimethylacetamide (DMAc) to prepare a polyimide solution having a solids content of 5 wt.%; stirring at normal temperature for 24h, slowly pouring the polyimide solution into a high-speed pulverizer containing alcohol solution (50 wt.%), pulverizing, filtering and collecting polyimide powder obtained by precipitation, fully washing with ethanol, and drying in a vacuum drying oven at 80 ℃ for 12h to obtain polyimide powder; pulverizing the powder again, sieving with 200 mesh sieve to obtain polyimide superfine powder, and filling the powder into rectangular stainless steel mold (80×60×120 mm) ³ ) In which the polyimide powder thickness was controlled to 5mm, a stainless steel mold was placed in a molding press (L0003-M1, IDM instrument, australia), and a polyimide molded sheet was prepared by the following procedure: 1) Slowly heating to 250 ℃ under the contact pressure; 2) When the temperature rises to 250 ℃, 1.5MPa pressure is applied, then the temperature is further increased to 300 ℃ and the mixture is kept for 1h under 2.0MPa pressure; 3) And (3) opening the die to obtain the polyimide engineering plastic die-pressed sheet with the thickness of 3mm.

Application example 2

The difference from application example 1 is that the polyimide was the polyimide prepared in example 2, and the rest was the same as application example 1.

Application example 3

The difference from application example 1 is that the polyimide was the polyimide prepared in example 3, and the rest was the same as application example 1.

Application example 4

The difference from application example 1 is that the polyimide was the polyimide prepared in example 4, and the rest was the same as application example 1.

Comparative application example 1

The difference from application example 1 is that polyimide was used in comparative example 1

YS-20 resin, the remainder was the same as in application example 1.

Comparative application example 2

The difference from application example 1 is that polyimide is in comparative example 2

PL450C resin, the remainder of which was identical to application example 1.

Performance testing

(1) Molecular weight: the polyimides prepared in examples 1 to 4 were subjected to molecular weight testing using an LC-20AD type Gel Permeation Chromatography (GPC) system from Shimadzu corporation, wherein N-methylpyrrolidone (NMP) was used as a mobile phase. The molecular weights obtained were number average molecular weights.

The polyimide prepared in example 1 had a number average molecular weight (Mn) of 93000g/mol; the polyimide prepared in example 2 had a number average molecular weight (Mn) of 100000g/mol; the polyimide prepared in example 3 had a number average molecular weight (Mn) of 113000g/mol; the polyimide prepared in example 4 had a number average molecular weight (Mn) of 131000g/mol.

(2) Fourier Transform Infrared (FTIR) spectroscopic testing of the polyimides prepared in examples 1 to 4: the wave number range was determined using a Tensor-27FT-IR spectrometer from Bruker, germany: 4000-400 cm ^-1 The results are shown in FIG. 1.

As can be seen from FIG. 1, the imide ring was accurately recognized at 1775cm ^-1 、1701cm ^-1 1381cm ^-1 Characteristic absorption peaks at.

(3) Thermal decomposition temperature: the thermal decomposition temperatures of the polyimide engineering plastic molded sheets prepared in application examples 1 to 4 were measured using a STA-8000 thermogravimetric analyzer (TGA) from Perkin-Elmer, U.S.A., at a temperature ranging from 30 to 760℃and a temperature rising rate of 20℃per minute, under a nitrogen atmosphere at a gas flow rate of 20mL/min, and the results are shown in FIG. 2.

As can be seen from FIG. 2, the polyimide engineering plastic molding sheets prepared by the method of the invention exhibit low thermal weight loss before 450 ℃, and begin to rapidly undergo thermal decomposition after the temperature exceeds 500 ℃.

(4) Glass transition temperature: the glass transition temperatures of the polyimide engineering plastic molded sheets prepared in application examples 1 to 4 were measured by using a DSC214 type Differential Scanning Calorimeter (DSC) of German resistant company, the measurement temperature range was 30 to 400 ℃, the temperature rise rate was 5 ℃/min, the measurement environment was nitrogen, and the gas flow rate was 20mL/min, and the results are shown in FIG. 3.

As can be seen from fig. 3, the glass transition temperature of the polyimide engineering plastic molding sheet prepared in application example 1 was 200.3 ℃, the glass transition temperature of the polyimide engineering plastic molding sheet prepared in application example 2 was 249.1 ℃, the glass transition temperature of the polyimide engineering plastic molding sheet prepared in application example 3 was 200.7 ℃, and the glass transition temperature of the polyimide engineering plastic molding sheet prepared in application example 4 was 253.1 ℃, and good heat stability was exhibited.

(5) Ultraviolet visible spectrum (UV-Vis): the polyimide engineering plastic molded sheets prepared in application examples 1 to 4 and the plastic molded sheets prepared in comparative application examples 1 and 2 were tested using a U-3210 spectrophotometer by Hitachi, japan, the results of the polyimide engineering plastic molded sheets prepared in application examples 1 to 4 are shown in FIG. 4, and ultraviolet cut-off wavelengths and light transmittance at wavelengths of 400nm and 760nm are shown in Table 1.

Table 1 optical properties of the plastic molded sheets prepared in application examples 1 to 4 and comparative application examples 1 to 2

As can be seen from table 1, the light transmittance of the polyimide engineering plastic molded sheets prepared according to the present invention is significantly higher than that of the wholly aromatic TPI molded sheets in the comparative examples, such as the material of comparative example 1 (λcut=487 nm; t400=0, t760=19.3%) based on 3,3', 4' -diphenyl ether tetracarboxylic dianhydride (ODPA) and 4,4' -diaminodiphenyl ether (ODA) and the material of commercial base

Comparative example 2 material of PL450C (λcut=602 nm; t400=0; t760=3.9%).

(6) CIE Lab parameters: the polyimide engineering plastic molded sheets prepared in application examples 1 to 4 and the plastic molded sheets prepared in comparative application examples 1 and 2 were measured using an X-rite Ci7800 spectrophotometer in the United states (film thickness: 25 μm, molded sheet thickness: 3 mm). L represents luminance, when it approaches 100, it tends to be white, and approaches 0 to be black; a in the parameters is a positive value indicating a red trend and a negative value indicating a green trend; the results are shown in table 1, where b is positive to indicate a yellow color and negative to indicate a blue color.

As can be seen from Table 1, the brightness (L) values of the polyimide engineering plastic molding sheets prepared by the invention are higher than 80, and the yellowness index (b) is between 20 and 30, which indicates that the colors of the materials are mainly bright yellow. In contrast, comparative example 1 had a value of L53.78, a as high as 21.34, and b as high as 87.93, indicating that the color is predominantly dark yellow and the color of comparative example 2 is predominantly black and red. The semi-crystalline molecular structure characteristic of comparative application example 2 is responsible for its poor light transmittance and high haze.

(7) The polyimide engineering plastic molded sheets prepared in application examples 2 and 4 and the plastic molded sheets prepared in comparative application examples 1 and 2 were cut to the required dimensions according to national standards, and subjected to performance tests such as stretching, bending, compression and the like, and the test methods were as follows:

tensile strength: was performed on an Instron model 5567 microcomputer controlled universal tester. Reference is made to the "determination of tensile Properties of plastics" in national Standard GB/T1040.2-2006. Part 2: test conditions for molding and extruding plastics "rectangular bars were used, with dimensions of about 150X 10X 4mm ³ The test temperature was room temperature and the sample loading rate was 2mm/min.

Flexural strength, flexural modulus: was performed on an Instron model 5567 microcomputer controlled universal tester. According to the 'determination of plastic bending property' in national standard GB/T9341-2008: test method for small samples "Plastic molded sheets were machined into rectangular bars with dimensions 80X 10X 4mm ³ The test temperature was room temperature and the sample loading rate was 2mm/min.

Compressive strength, compression modulus: was performed on an Instron model 5567 microcomputer controlled universal tester. According to the "measurement of Plastic compression Property" of national Standard GB/T1041-2008, a plastic molded sheet was machined to a size of about 10X 4mm ³ Is measured at room temperature.

Impact strength: the test was performed on an XJUD-5.5 cantilever impact tester. Determination of impact Properties of Plastic simply-supported Beam according to national Standard GB/T1043.1-2008 part 1: non-instrumented impact test "by machining a plastic molded sheet to a size of about 80X 10X 4mm ³ Is measured at room temperature.

The test results are shown in Table 2.

TABLE 2 mechanical Properties of Plastic molded sheets

As is clear from Table 2, the polyimide engineering plastic molded sheet prepared in application example 2 had a flexural strength of 159.0.+ -. 2.3MPa, a flexural modulus of 3.46.+ -. 0.13GPa, a compressive strength of 159.3.+ -. 1.5MPa, a compressive modulus of 1.58.+ -. 0.27GPa, and an impact strength of 55.8.+ -. 16.8KJ/m ² Tensile strength of 116.8.+ -. 0.8MPa and elongation of 12.02.1% and a heat distortion temperature of 235.7 ℃.

The polyimide engineering plastic molded sheet prepared in application example 4 has a bending strength of 181.8+ -3.9 MPa, a bending modulus of 4.08+ -0.07 GPa, a compression strength of 154.0+ -2.9 MPa, a compression modulus of 1.64+ -0.35 GPa, and an impact strength of 70.8+ -16.5 KJ/m ² The tensile strength was 138.5.+ -. 0.6MPa, the elongation was 17.4.+ -. 1.2% and the heat distortion temperature was 213.0 ℃.

As can be seen from the data shown in Table 2, the polyimide engineering plastics prepared by the invention have the advantages of higher Heat Distortion Temperature (HDT), outstanding bending strength and bending modulus, and higher compressive strength and tensile strength. The performance disadvantages are mainly reflected in relatively low elongation at break and impact strength. For example, the HDT in application example 2 and application example 4 were 235.7℃and 213.0 ℃respectively in terms of heat stability. The former employs the HDT of example 2 to be comparable to the higher levels of the current commercial TPI materials. It is noted that the glass transition temperatures of the materials of application example 2 and application example 4 were 249.1 ℃ and 253.1 ℃, respectively. Although the glass transition temperature value of application example 4 was 4℃higher than that of example 2, the HDT value was 22.7℃lower than that of application example 2. Since the glass transition temperature test is performed under an unstressed condition, the HDT test is performed under a certain load. It can be seen that PI materials based on ctHPMDA (application example 3 and application example 4) are more prone to deformation under a certain load, mainly due to their spatial configuration. In terms of bending performance, the bending strengths of application example 2 and application example 4 are 159.0 + -2.3 MPa and 181.8+ -3.9 MPa, respectively, and the bending moduli thereof are 3.46+ -0.13 GPa and 4.08+ -0.07 GPa, respectively, which are at high levels in all materials. In terms of compression properties, the materials of application example 2 and application example 4 exhibited higher compressive strength, but their compressive modulus was relatively low. The materials of application example 2 and application example 4 also exhibited higher tensile strength in terms of tensile properties, but their elongation at break was relatively low. In terms of impact strength, the materials of application example 2 and application example 4 were at a lower level in all materials. Therefore, the TPI engineering plastic developed by the invention is more suitable for manufacturing the bending-resistant and pressure-resistant parts in high-temperature environments (less than or equal to 210 ℃).

Although the foregoing embodiments have been described in some, but not all, embodiments of the invention, according to which one can obtain other embodiments without inventiveness, these embodiments are all within the scope of the invention.

Claims

1. The preparation method of the thermoplastic polyimide engineering plastic is characterized by comprising the following steps of:

setting up a 1000mL four-necked glass flask consisting of a mechanical stirrer, a tetrafluoro stirring rod, a thermometer, a Dean-Stark water separator and a dry nitrogen inlet and outlet in a clean room, adding 120.0g of gamma-butyrolactone into the flask, introducing nitrogen into the flask, adding 29.234g of 1, 3-bis (3-aminophenoxy) benzene 133APB, stirring for 10min under the protection of nitrogen at normal temperature to obtain a homogeneous solution, adding 22.4170g of 0.1mol of 1S,2R,4S, 5R-hydrogenated pyromellitic dianhydride into the homogeneous solution, simultaneously adding 35.0g of gamma-butyrolactone, the mass ratio of 1, 3-bis (3-aminophenoxy) benzene to 1S,2R,4S, 5R-hydrogenated pyromellitic dianhydride to the total mass of 1, 3-bis (3-aminophenoxy) benzene, 1S,2R,4S, 5R-hydrogenated pyromellitic dianhydride and gamma-butyrolactone is 25:100, and stirring at 25 ℃ for 3h to obtain a polyamic acid solution; adding 150g of toluene and 0.5g of isoquinoline into the polyamic acid solution, heating to 130 ℃, distilling off the azeotrope of toluene and water in a reaction system, maintaining reflux dehydration for 6 hours until no water in a water separator is distilled off, continuously heating to 180 ℃, distilling off excessive toluene through the water separator, replacing the water separator with a reflux condenser tube, maintaining constant temperature for continuous reaction for 3 hours, naturally cooling to normal temperature, slowly pouring the obtained pale yellow viscous solution into excessive 75vol% alcohol solution to obtain pale yellow filamentous precipitate, standing overnight, filtering and collecting obtained resin, fully washing with ethanol, and vacuum drying at 80 ℃ for 24 hours to obtain filamentous polyimide; the polyimide structure is as follows:

a 500mL three-necked flask was charged with dried 10.0g of the polyimide and 190g of ultra-dry dimethylacetamide to prepare a polyimide solution having a solids content of 5 wt.%; stirring at normal temperature for 24 hours, slowly pouring the polyimide solution into a high-speed pulverizer with 50wt.% of alcoholic solution for pulverization, filtering and collecting polyimide powder obtained by precipitation, fully washing with ethanol, and drying in a vacuum drying oven at 80 ℃ for 12 hours to obtain polyimide powder; pulverizing the powder again, sieving with 200 mesh sieve to obtain polyimide superfine powder, and filling the powder into 80×60×120mm ³ The polyimide powder thickness was controlled to 5mm, and the stainless steel mold was placed in a molding press to prepare a polyimide molded sheet by the following procedure: 1) Slowly heating to 250 ℃ under the contact pressure; 2) When the temperature rises to 250 ℃, 1.5MPa pressure is applied, then the temperature is further increased to 300 ℃ and the mixture is kept for 1h under 2.0MPa pressure; 3) And (3) opening the die to obtain the polyimide engineering plastic die-pressed sheet with the thickness of 3mm.