Toughened and modified polyimide thermosetting resin as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of thermosetting resin, and particularly relates to toughened and modified polyimide thermosetting resin as well as a preparation method and application thereof. The invention provides toughened and modified polyimide thermosetting resin which has a structure as shown in a formula I. According to the invention, the long alkyl chain amino-terminated monomer is introduced into the main molecular chain of the polyimide thermosetting resin, and the flexible unit is embedded into the cross-linked three-dimensional network structure, so that the impact toughness of the polyimide thermosetting resin can be effectively improved while the high glass transition temperature of the resin material is maintained. The polyimide thermosetting resin disclosed by the invention does not use MDA monomers and methanol, so that the harm and pollution of the resin to human bodies and the environment are avoided. The thermosetting resin used in the invention is synthesized by only one-step esterification reaction and only one reaction kettle, the esterification reaction temperature is low, the process is simple, the energy consumption is saved, and the cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of thermosetting resins, and in particular relates to a toughened and modified polyimide thermosetting resin and a preparation method and application thereof. Background Art

[0002] In 1972, NASA Lewis Research Center in the United States first reported the preparation of PMR-15 polyimide thermosetting resin by in-situ polymerization of monomer reactants (Thermal Stable Polyimide from Solutions of Monomeric Reactants, J. Appl. Polym. Sci., 1972, 16:905; US Patent 3,745,149). The glass transition temperature (T g ) up to 316℃, and has been widely used in a variety of high-tech fields such as aviation, aerospace, and oil extraction. In the following decades, T g Higher polyimide thermosetting resin. However, the cross-linked three-dimensional network structure formed by the reaction of diamine with dianhydride and end-capping agent improves the heat resistance and dimensional stability of the material, but also increases the brittleness of the material. When subjected to impact, it is difficult to absorb and disperse the impact energy, and cracks are formed and quickly collapsed, causing huge economic losses to the application of aerospace and automobile manufacturing industries.

[0003] At present, the methods for improving the toughness of thermosetting polyimide composites mainly include toughening modification methods of molecular main chain structure and thermoplastic polymer blending. Among them, the toughening modification method based on the molecular main chain structure aims to solve the performance problem of toughness in the most direct and effective way and fundamentally, which has attracted the attention of many researchers and has become a hot research direction. LaRC-RP46 and the LP series resins developed by Aviation Industry Composites Co., Ltd. respectively use 3,4-diaminodiphenyl ether and bisphenol A diphenyl ether diamine with flexible segments to synthesize thermosetting polyimide resins. Compared with PMR-15 prepared with diaminodiphenylmethane monomer, its toughness performance has not been greatly improved. Similarly, Changchun Institute of Applied Chemistry uses thioether dianhydride instead of ketoanhydride in PMR-15, and the interlaminar fracture toughness is increased by 5-7 times, and the glass transition temperature is also increased by 60°C. However, thioether dianhydride is expensive, resulting in high resin cost. In the 1990s, NASA developed polyimide resins terminated with phenylethynyl groups under the support of the HSCT program. Among them, the polyimide composite material prepared with PETI-5 showed a toughness level that reached high-toughness epoxy resin-based composite materials. However, while improving the toughness of the polyimide resin matrix and the composite material, the increase in the length of the chain segments between the crosslinking points leads to a decrease in the crosslinking density, thus sacrificing heat resistance and process performance to a certain extent. In addition, phenylethynyl end-capping agents and thioether dianhydride also have the problem of being expensive.

[0004] Another toughening method using thermoplastic polymer blending technology to obtain a semi-interpenetrating network is one of the effective toughening methods for thermosetting composites, but the difficulty lies in the control of the process. Selecting a thermoplastic polymer that matches the main chain structure of thermosetting polyimide is the key to obtaining a semi-interpenetrating network and achieving blending toughening. The heat resistance must be similar to that of the matrix resin, otherwise it will affect the use temperature of the toughened modified composite material. The composite materials prepared by the blending toughening modification method often have a high porosity. Due to the introduction of the toughening component, the process performance of the original resin is reduced, which is also the main problem of the blending method.

[0005] Therefore, currently polyimide thermosetting resin materials still cannot guarantee high heat resistance and excellent impact toughness at the same time. Summary of the invention

[0006] The object of the present invention is to provide a toughened and modified polyimide thermosetting resin and a preparation method and application thereof. The toughened and modified polyimide thermosetting resin provided by the present invention can greatly improve its toughness without affecting the original high glass transition temperature.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides a toughened and modified polyimide thermosetting resin having a structure shown in Formula I:

[0009]

[0010] In formula I: Ar1 is a residue of an aromatic diamine monomer, Ar1 is selected from one or more of a phenyl group, a biphenyl group, a substituted biphenyl group, a diphenyl ether group and a triphenyl ether group, and the substituent of the substituted biphenyl group is a C1-10 alkyl group or a halogen-substituted C1-10 alkyl group;

[0011] Ar2 is a residue of an aromatic dianhydride monomer, and Ar2 is selected from one or more of a phenyl group, a biphenyl group, a diphenyl ether group, and a benzophenone group;

[0012] Ar3 is a residue of a long alkane chain diamine monomer, and the number of carbon atoms in Ar3 is 5 to 10;

[0013] n is a positive integer of 1-5, and m is a positive integer of 1-3.

[0014] Preferably, Ar1 is selected from any one or more of the structures represented by the following formulas (1) to (7):

[0015]

[0016] Preferably, Ar2 is selected from any one or more of the structures shown in the following formulas (8) to (14):

[0017]

[0018] Preferably, the long alkane chain diamine monomer is selected from one or more of 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane and 1,10-diaminodecane.

[0019] Preferably, the toughened and modified polyimide thermosetting resin has a glass transition temperature of 300 to 420°C and an impact toughness of 6.82 to 8.34 kJ / m 2 .

[0020] The present invention provides a method for preparing a monomer mixture solution of a toughened and modified polyimide thermosetting resin according to the above technical solution, comprising the following steps:

[0021] The aromatic dianhydride monomer, the reactive end-capping agent and the alcohol solvent are mixed to carry out an esterification reaction to obtain an esterification solution;

[0022] The esterification solution, aromatic diamine monomer, long alkane chain diamine monomer and alcohol solvent are mixed to obtain the monomer mixture solution of the toughened and modified polyimide thermosetting resin.

[0023] Preferably, the reactive end-capping agent is nadic anhydride; the mass ratio of the aromatic dianhydride monomer to the reactive end-capping agent is 100:(20-55);

[0024] The mass ratio of the aromatic dianhydride monomer to the aromatic diamine monomer is 100:(80-130);

[0025] The mass ratio of the aromatic dianhydride monomer to the long alkane chain diamine monomer is 100:(5-10).

[0026] Preferably, the temperature of the esterification reaction is 60-100° C. and the time is 2-6 hours.

[0027] The present invention provides a method for preparing a toughened and modified polyimide thermosetting resin molding powder according to the above technical solution, comprising the following steps:

[0028] According to the preparation method described in the above technical solution, a monomer mixture solution of the toughened and modified polyimide thermosetting resin described in the above technical solution is obtained;

[0029] The monomer mixture solution of the toughened and modified polyimide thermosetting resin is sequentially concentrated and heat-treated to obtain molding powder of the toughened and modified polyimide thermosetting resin.

[0030] The present invention provides the use of the toughened modified polyimide thermosetting resin described in the above technical scheme or the monomer mixture solution of the toughened modified polyimide thermosetting resin prepared by the preparation method described in the above technical scheme or the molding powder of the toughened modified polyimide thermosetting resin prepared by the preparation method described in the above technical scheme in pure resin molded parts or resin-based carbon fiber composite materials.

[0031] The present invention provides a toughened and modified polyimide thermosetting resin having a structure shown in Formula I; wherein: Ar1 is a residue of an aromatic diamine monomer, Ar1 is selected from one or more of phenyl, biphenyl, substituted biphenyl, diphenyl ether and triphenyl ether, and the substituent of the substituted biphenyl is a C1-10 alkyl or a halogen-substituted C1-10 alkyl; Ar2 is a residue of an aromatic dianhydride monomer, Ar2 is selected from one or more of phenyl, biphenyl, diphenyl ether and benzophenone; Ar3 is a residue of a long alkane chain diamine monomer, and the number of carbon atoms in Ar3 is 5-10; n is a positive integer of 1-5, and m is a positive integer of 1-3. The toughened and modified polyimide thermosetting resin described in the present invention can greatly improve its toughness without affecting the original high glass transition temperature.

[0032] The present invention has the following beneficial effects:

[0033] The present invention introduces long alkyl chain terminal amino monomers into the main molecular chain of polyimide thermosetting resin, embeds flexible units into a cross-linked three-dimensional network structure, and can effectively improve the impact toughness of polyimide thermosetting resin while maintaining a high glass transition temperature of the resin material.

[0034] The polyimide thermosetting resin of the present invention does not use MDA monomer and methanol solution, thus avoiding the harm and pollution of the resin to human body and environment.

[0035] The thermosetting resin used in the present invention uses only one-step esterification reaction, and only one reactor is used to complete the synthesis of the resin. The esterification reaction temperature is low, the process is simple, energy consumption is saved, and the cost is reduced. DETAILED DESCRIPTION

[0036] The present invention provides a toughened and modified polyimide thermosetting resin having a structure shown in Formula I:

[0037]

[0038] In formula I: Ar1 is a residue of an aromatic diamine monomer, Ar1 is selected from one or more of a phenyl group, a biphenyl group, a substituted biphenyl group, a diphenyl ether group and a triphenyl ether group, and the substituent of the substituted biphenyl group is a C1-10 alkyl group or a halogen-substituted C1-10 alkyl group;

[0039] Ar2 is a residue of an aromatic dianhydride monomer, and Ar2 is selected from one or more of a phenyl group, a biphenyl group, a diphenyl ether group, and a benzophenone group;

[0040] Ar3 is a residue of a long alkane chain diamine monomer, and the number of carbon atoms in Ar3 is 5 to 10;

[0041] n is a positive integer of 1-5, and m is a positive integer of 1-3.

[0042] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0043] The m toughened and modified polyimide thermosetting resin of the structure shown in Formula I provided by the present invention Unit and n The arrangement order of the units is free to combine, and the structure shown in formula 1 only indicates Unit and The number of units and the connection relationship with the end-capping group.

[0044] In the present invention, the substituent of the substituted biphenyl group is a C1-10 alkyl group or a halogen-substituted C1-10 alkyl group. The C1-10 alkyl group is preferably a C1-5 alkyl group, and is particularly preferably a methyl group, an ethyl group, a propyl group or a butyl group. The halogen-substituted C1-10 alkyl group is preferably a halogen-substituted C1-5 alkyl group, and is particularly preferably a halogen-substituted methyl group, a halogen-substituted ethyl group, a halogen-substituted propyl group or a halogen-substituted butyl group. The halogen is preferably F, Cl or Br.

[0045] In the present invention, Ar1 is preferably selected from any one or more of the structures represented by the following formulas (1) to (7):

[0046]

[0047] In the present invention, Ar2 is preferably selected from any one or more of the structures represented by the following formulas (8) to (14):

[0048]

[0049] In the present invention, the long alkane chain diamine monomer is preferably selected from one or more of 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane and 1,10-diaminodecane.

[0050] In the present invention, the glass transition temperature of the toughened and modified polyimide thermosetting resin is preferably 300 to 420°C, and the impact toughness is preferably 6.82 to 8.34 kJ / m 2 .

[0051] The present invention provides a method for preparing a monomer mixture solution of a toughened and modified polyimide thermosetting resin according to the above technical solution, comprising the following steps:

[0052] The aromatic dianhydride monomer, the reactive end-capping agent and the alcohol solvent are mixed to carry out an esterification reaction to obtain an esterification solution;

[0053] The esterification solution, aromatic diamine monomer, long alkane chain diamine monomer and alcohol solvent are mixed to obtain the monomer mixture solution of the toughened and modified polyimide thermosetting resin.

[0054] The present invention mixes an aromatic dianhydride monomer, a reactive end-capping agent and an alcohol solvent (hereinafter referred to as the first alcohol solvent) for esterification reaction to obtain an esterification solution. In the present invention, the aromatic dianhydride monomer preferably includes 3,3,4,4-benzophenone tetracarboxylic dianhydride (BTDA), 4,4-diphenyl ether tetracarboxylic dianhydride (ODPA) or bisphenol A dianhydride (BPADA). The reactive end-capping agent is preferably nadic anhydride (NA). The mass ratio of the aromatic dianhydride monomer and the reactive end-capping agent is preferably 100: (20-55), and in the embodiment, it is specifically 100: 40, 100: 48, 100: 30, 100: 52 or 100: 42. The first alcohol solvent is preferably methanol and / or ethanol, and in the embodiment, it is specifically ethanol. The first alcohol solvent is preferably an anhydrous alcohol solvent. In the present invention, the mixing of the aromatic dianhydride monomer, the reactive end-capping agent and the alcohol solvent preferably includes: adding the aromatic dianhydride monomer and the reactive end-capping agent to the first alcohol solvent. The esterification reaction is preferably carried out under heating reflux, and the temperature of the esterification reaction is preferably 60 to 100° C., more preferably 70 to 80° C. The time of the esterification reaction is preferably 2 to 6 hours, more preferably 3 to 4 hours. The time of the esterification reaction cannot be too long, otherwise it will lead to excessive esterification of the aromatic dianhydride monomer, affecting the subsequent toughening and modification of the polyimide thermosetting resin molding powder and the further processing of the prepreg.

[0055] After obtaining the esterification solution, the present invention mixes the esterification solution, aromatic diamine monomer, long alkane diamine monomer and alcohol solvent (hereinafter referred to as the second alcohol solvent) to obtain the monomer mixture solution of the toughened modified polyimide thermosetting resin. In the present invention, the aromatic diamine monomer is preferably 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl (m-TOL) or 3,4'-diaminodiphenyl ether (3,4'-ODA). The number of carbon atoms in the long alkane chain diamine monomer is preferably 5 to 10, and the long alkane chain diamine monomer is preferably selected from one or more of 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, and 1,10-diaminodecane; more preferably selected from one or more of 1,7-diaminoheptane (Z7Z), 1,8-diaminooctane (Z8Z), 1,9-diaminononane (Z9Z) and 1,10-diaminodecane (Z10Z). The mass ratio of the aromatic dianhydride monomer to the aromatic diamine monomer is preferably 100:(80 to 130), more preferably 100:(80 to 120), and specifically 100:98, 100:86, 100:90, 100:82 or 100:80 in the embodiments. The mass ratio of the aromatic dianhydride monomer to the long alkane diamine monomer is preferably 100:(5-10), and in the embodiment, it is specifically 100:8, 100:7, 100:9 or 100:10. The second alcohol solvent is preferably methanol and / or ethanol, and in the embodiment, it is specifically ethanol. The second alcohol solvent is an anhydrous alcohol solvent. In the present invention, the mixing of the esterification solution, the aromatic diamine monomer, the long alkane diamine monomer and the second alcohol solvent preferably includes: adding the aromatic diamine monomer and the long alkane diamine monomer to the esterification solution, then adding the second alcohol solvent, and finally stirring and mixing in a protective gas atmosphere. The present invention has no special requirements for the amount of the second alcohol solvent, and ensures that the solid content of the mixture solution obtained after adding the second alcohol solvent is preferably 50-80%. In the present invention, the stirring and mixing is preferably carried out in a protective gas atmosphere, and the protective gas is preferably nitrogen. The temperature of the stirring and mixing is preferably 25-30°C, and the time is preferably 5-15h.

[0056] In the present invention, the solid content of the monomer mixture solution of the toughened and modified polyimide thermosetting resin is preferably 50-80%.

[0057] The present invention provides a method for preparing a toughened and modified polyimide thermosetting resin molding powder according to the above technical solution, comprising the following steps:

[0058] According to the preparation method described in the above technical solution, a monomer mixture solution of the toughened and modified polyimide thermosetting resin described in the above technical solution is obtained;

[0059] The toughened and modified polyimide thermosetting resin monomer mixture solution is sequentially concentrated and heat-treated to obtain the toughened and modified polyimide thermosetting resin molding powder.

[0060] In the present invention, the concentration is preferably vacuum rotary evaporation, and the concentration temperature is preferably 50-80°C, more preferably 60°C. If the concentration temperature is too high, the resin liquid will easily boil and burst. The heat treatment is preferably forced air drying, and the temperature control procedure of the heat treatment preferably includes: heating from room temperature to a first temperature for a first insulation; after the first insulation, continue to heat from the first temperature to a second temperature for a second insulation, after the second insulation, continue to heat from the second temperature to a third temperature for a third insulation, and after the third insulation, continue to heat from the third temperature to a fourth temperature for a fourth insulation. The second temperature is preferably 70-90°C, more preferably 90°C; the first insulation time is preferably 1-1.5h, more preferably 1.5h; the second temperature is preferably 100-130°C, more preferably 130°C; the second insulation time is preferably 1h, the third temperature is preferably 150-170°C, more preferably 170°C; the third insulation time is preferably 1h, the fourth temperature is preferably 180-220°C, more preferably 200°C; the fourth insulation time is preferably 2h. In the present invention, during the heat treatment process, the resin in the concentrated resin solution gradually foams and expands, during which water and alcohol solvent are removed between the aromatic dianhydride monomer, the aromatic diamine monomer and the reactive end-capping agent to form polyimide molecules end-capped with nadic anhydride. In the present invention, a thermal imidization reaction occurs during the heat treatment process of preparing the molding powder.

[0061] In the present invention, after the heat treatment is completed, a heat treatment product is obtained. In the present invention, the heat treatment product is preferably crushed and ground in sequence to obtain a toughened and modified polyimide thermosetting resin molding powder. The present invention has no special requirements for the specific implementation process of the crushing and grinding.

[0062] In the present invention, the toughened and modified polyimide thermosetting resin of the structure shown in Formula I is prepared by mixing an esterified solution of an aromatic dianhydride monomer and a reactive end-capping agent with a long alkane diamine and an aromatic diamine monomer to obtain a monomer mixture solution; and subjecting the monomer mixture solution to a heat treatment (thermal imidization reaction) to obtain a molding powder of the toughened and modified polyimide thermosetting resin. The preparation method provided by the present invention is simple to operate and is suitable for industrial production.

[0063] The present invention provides the use of the toughened modified polyimide thermosetting resin described in the above technical scheme or the monomer mixture solution of the toughened modified polyimide thermosetting resin prepared by the preparation method described in the above technical scheme or the molding powder of the toughened modified polyimide thermosetting resin prepared by the preparation method described in the above technical scheme in pure resin molded parts or resin-based carbon fiber composite materials.

[0064] In the present invention, when the toughened and modified polyimide thermosetting resin is applied to a pure resin molded part, the preparation method of the pure resin molded part preferably comprises the following steps:

[0065] The molding powder of the toughened and modified polyimide thermosetting resin is loaded into a mold; then hot pressing is performed to obtain the compression molded part of the pure resin.

[0066] In the present invention, the mold is preferably a steel mold, and the mold includes a mold sleeve, a lower mold core and an upper mold core. Before the mold is used, the present invention preferably coats a release agent on the mold surface, and then dries it at room temperature, and the drying time is preferably 10 minutes. The hot pressing is carried out in a hot press, and the temperature control program of the hot pressing preferably includes: heating from room temperature to the first temperature at a first heating rate for the first insulation, after the first insulation is completed, heating from the first temperature to the second temperature at a second heating rate, starting from the second temperature for pressurization, under pressurization, heating from the second temperature to the third temperature at a third heating rate for the third insulation, and releasing the pressure after the third insulation is completed. The first heating rate is preferably 5°C / min. The first temperature is preferably 200°C, and the first insulation time is preferably 30min. The second heating rate is preferably 4°C / min, the second temperature is preferably 240°C, the pressure of the pressurization is 1.5-2MPa, the third heating rate is preferably 2°C / min, the third temperature is preferably 320°C, and the third insulation time is preferably 2h.

[0067] As a specific application example of the present invention, a method for preparing a pure resin molded part using a toughened and modified polyimide thermosetting resin molding powder specifically includes:

[0068] a) Assemble the mold sleeve and lower mold core of the steel mold, spray the release agent on the mold surface, and dry it at room temperature for 10 minutes;

[0069] b) Pour the molding powder into the mold, evenly stack it, and slowly press the upper mold core into the mold sleeve;

[0070] c) Place the mold on the heating plate of the hot press and set the following program for hot pressing:

[0071] Room temperature (turn on cooling cycle machine)—(5℃ / min)—200℃ / 30min—(4℃ / min)

[0072] —240℃ (apply 1.5~2MPa pressure)—(2℃ / min)—320℃ / 2h (observe the pressure and adjust appropriately)—release the pressure after the insulation is completed.

[0073] In the present invention, when the toughened and modified polyimide thermosetting resin is applied to a resin-based carbon fiber composite material, the method for preparing the resin-based carbon fiber composite material preferably comprises the following steps:

[0074] The solution of the toughened and modified polyimide thermosetting resin is coated on the carbon fiber cloth, and then dried and hot-pressed in sequence to obtain the resin-based carbon fiber composite material.

[0075] In the present invention, the drying is preferably air-drying. The hot pressing is carried out in a hot press, and the temperature control program of the hot pressing preferably includes: heating from room temperature to a first temperature at a first heating rate for a first insulation, after the first insulation is completed, heating from the first temperature to a second temperature at a second heating rate for a second insulation, after the second insulation is completed, heating from the second temperature to a third temperature at a third heating rate, starting pressurization from the third temperature without insulation, under pressurized conditions, heating from the third temperature to a fourth temperature at a fourth heating rate for a fourth insulation, and releasing the pressure after the fourth insulation is completed. The first heating rate is preferably 3°C / min. The room temperature is 25°C, the first temperature is preferably 150°C, and the first insulation time is preferably 30min. The second heating rate is preferably 0.5°C / min, the second temperature is preferably 200°C, the second insulation time is preferably 120min, the third heating rate is preferably 3°C / min, the third temperature is preferably 240-244°C, the pressurization pressure is 1.5-2MPa, the fourth heating rate is preferably 2°C / min, the fourth temperature is preferably 320°C, and the fourth insulation time is preferably 2h.

[0076] The pressure data in the present invention are all relative pressure data.

[0077] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0078] Example 1

[0079] A method for preparing a monomer mixture solution of a toughened and modified polyimide thermosetting resin is provided: 100 parts of 3,3,4,4-benzophenonetetracarboxylic dianhydride (BTDA) and 48 parts of nadic anhydride (NA) are added to a three-necked flask containing 118 parts of ethanol, a stirring blade, a condenser, a nitrogen branch pipe, and a thermometer are added, and an ethanol solution of BTDE and NE is obtained by esterification reaction at 80°C for 4 hours; 7 parts of 1,10-diaminodecane (Z10Z) and 98 parts of 4,4′-diamino-2,2′-dimethyl-1,1′-biphenyl (m-TOL) are added to the ethanol solution of BTDE and NE, and the ethanol solution is supplemented until the solid content is 50%. Stirring is continued for 15 hours under nitrogen protection at room temperature to fully dissolve m-TOL and Z10Z, and then the monomer mixture solution BNT50-Z107 of the toughened and modified polyimide thermosetting resin of Z10Z is obtained.

[0080] The Tg of the toughened and modified polyimide thermosetting resin prepared in this embodiment is about 416°C, which is basically consistent with the Tg of 414°C of the polyimide thermosetting resin with the same monomer combination without Z10Z toughening modification. Its impact toughness is between 6.82 and 7.85 Jm 2 .

[0081] Among them, the preparation method of the polyimide thermosetting resin of the same monomer combination without Z10Z toughening modification (i.e., the product of Comparative Example 1) is basically the same as that of Example 1, except that the preparation raw material of "7 parts of 1,10-diaminodecane (Z10Z)" is omitted.

[0082] Example 2

[0083] The preparation method is basically the same as that of Example 1, except that the amount of Z10Z used is 5 parts.

[0084] Example 3

[0085] The preparation method is basically the same as that of Example 1, except that the amount of Z10Z used is 10 parts.

[0086] Comparative Example 1

[0087] The preparation method is basically the same as that of Example 1, except that the amount of Z10Z used is 0 parts.

[0088] Example 4

[0089] A method for preparing a monomer mixture solution of a toughened and modified polyimide thermosetting resin is provided: 100 parts of 3,3,4,4-benzophenone tetracarboxylic dianhydride (BTDA) and 30 parts of norbornene anhydride (NA) are added to a three-necked flask containing 105 parts of ethanol, a stirring paddle, a condenser, a nitrogen branch pipe, and a thermometer are added, and an esterification reaction is carried out at 80°C for 4 hours to obtain an ethanol solution of BTDE and NE; 9 parts of 1,8-diaminooctane (Z8Z) and 86 parts of 3,4′-diaminodiphenyl ether (3,4′-ODA) are added to the ethanol solution of BTDE and NE, and the ethanol solution is supplemented until the solid content is 50%. Stirring is continued for 15 hours at room temperature and under nitrogen protection, 3,4′-ODA and Z8Z are fully dissolved, and then the monomer mixture solution BNO50-Z89 of the toughened and modified polyimide thermosetting resin of Z8Z is obtained.

[0090] The Tg of the toughened and modified polyimide thermosetting resin prepared in this embodiment is about 386°C, which is basically consistent with the Tg of 385°C of the polyimide thermosetting resin of the same monomer combination without Z8Z toughening modification, and its impact toughness is between 7.26 and 8.04 Jm 2 .

[0091] The preparation method of the polyimide thermosetting resin of the same monomer combination without Z8Z toughening modification is basically the same as that of Example 2, except that the preparation raw material of "9 parts of 1,8-diaminooctane (Z8Z)" is omitted.

[0092] Example 5

[0093] A method for preparing a monomer mixture solution of a toughened and modified polyimide thermosetting resin is provided: 100 parts of 4,4-diphenyl ether tetracarboxylic dianhydride (ODPA) and 52 parts of nadic anhydride (NA) are added to a three-necked flask containing 120 parts of ethanol, a stirring blade, a condenser, a nitrogen branch pipe, and a thermometer are added, and an ethanol solution of ODPE and NE is obtained by esterification reaction at 80°C for 4 hours; 10 parts of 1,9-diaminononane (Z9Z) and 90 parts of 3,4′-diaminodiphenyl ether (3,4′-ODA) are added to the ethanol solution of ODPE and NE, and the ethanol solution is supplemented until the solid content is 45%. Stirring is continued for 15 hours at room temperature and under nitrogen protection, 3,4′-ODA and Z9Z are fully dissolved, and then the monomer mixture solution ONO45-Z910 of the Z9Z toughened and modified polyimide thermosetting resin is obtained.

[0094] The Tg of the toughened and modified polyimide thermosetting resin prepared in this embodiment is about 350°C, which is close to the Tg of 356°C of the non-Z9Z toughened and modified polyimide thermosetting resin. Its impact toughness is between 7.55 and 8.23 ​​Jm. 2 .

[0095] The preparation method of the polyimide thermosetting resin of the same monomer combination without Z9Z toughening modification is basically the same as that of Example 3, except that the preparation raw material of "10 parts of 1,9-diaminononane (Z9Z)" is omitted.

[0096] Example 6

[0097] A method for preparing a monomer mixture solution of a toughened and modified polyimide thermosetting resin is provided: 100 parts of bisphenol A dianhydride (BPADA) and 42 parts of nadic anhydride (NA) are added to a three-necked flask containing 95 parts of ethanol, a stirring blade, a condenser, a nitrogen branch pipe, and a thermometer are added, and an esterification reaction is carried out at 80°C for 4 hours to obtain an ethanol solution of BPADE and NE; 10 parts of 1,7-diaminoheptane (Z7Z) and 82 parts of 4,4′-diamino-2,2′-dimethyl-1,1′-biphenyl (m-TOL) are added to the ethanol solution of BPADE and NE, and the ethanol solution is supplemented until the solid content is 55%. Stirring is continued for 15 hours at room temperature and under nitrogen protection, 3,4′-ODA and Z7Z are fully dissolved, and then the monomer mixture solution BPNT55-Z710 of a Z7Z toughened and modified polyimide thermosetting resin is obtained.

[0098] The Tg of the toughened and modified polyimide thermosetting resin prepared in this embodiment is about 326°C, which is close to the Tg of 330°C of the non-Z7Z toughened and modified polyimide thermosetting resin. Its impact toughness is between 7.42 and 8.16 Jm 2 .

[0099] The preparation method of the polyimide thermosetting resin of the same monomer combination without Z7Z toughening modification is basically the same as that of Example 4, except that the preparation raw material of "10 parts of 1,7-diaminoheptane (Z7Z)" is omitted.

[0100] Example 7

[0101] A method for preparing a monomer mixture solution of a toughened and modified polyimide thermosetting resin is provided: 100 parts of bisphenol A dianhydride (BPADA) and 42 parts of norbornene anhydride (NA) are added to a three-necked flask containing 95 parts of ethanol, a stirring blade, a condenser, a nitrogen branch pipe, and a thermometer are added, and an esterification reaction is carried out at 80°C for 4 hours to obtain an ethanol solution of BPADE and NE; 7 parts of 1,10-diaminodecane (Z10Z) and 80 parts of 3,4′-diaminodiphenyl ether (3,4′-ODA) are added to the ethanol solution of BPADE and NE, and the ethanol solution is supplemented until the solid content is 55%. Stirring is continued for 15 hours at room temperature and under nitrogen protection to fully dissolve 3,4′-ODA and Z10Z, and then the monomer mixture solution BPNO55-Z107 of a Z10Z toughened and modified polyimide thermosetting resin is obtained.

[0102] The Tg of the toughened and modified polyimide thermosetting resin prepared in this embodiment is about 308°C, which is close to the Tg of 312°C of the polyimide thermosetting resin without Z10Z toughening and modification. Its impact toughness is between 7.68 and 8.34 J m 2 .

[0103] The preparation method of the polyimide thermosetting resin of the same monomer combination without Z10Z toughening modification is basically the same as that of Example 5, except that the preparation raw material of "7 parts of 1,10-diaminodecane (Z10Z)" is omitted.

[0104] Application Example 1

[0105] In order to investigate the toughening effect of the polyimide thermosetting resin prepared in the above examples, this application example uses the monomer mixture solution (solid content of 50%) of the toughened and modified polyimide thermosetting resin prepared in the above examples 1, 2, 3 and comparative example 1 as the matrix resin and carbon fiber to prepare a composite material. The preparation method of the polyimide thermosetting resin toughened carbon fiber composite material provided in this application example is carried out according to the following steps:

[0106] 1) Cut a carbon fiber cloth of a certain size, weigh it and record it as m1, prepare a release paper larger than the carbon fiber cloth and lay it flat under the carbon fiber cloth;

[0107] 2) Weigh a certain amount of a monomer mixture solution of a toughened and modified polyimide thermosetting resin prepared in Example 1, Example 2, Example 3 or Comparative Example 1, wherein the weight of the resin (dry weight) is two-thirds of the weight of the carbon fiber cloth;

[0108] 3) Use a brush to evenly apply the resin solution on the carbon fiber cloth, cover it with a layer of release paper, and use a roller to continuously roll the resin solution to make it more evenly distributed in the carbon fiber cloth;

[0109] 4) Tear off the surface release paper, place in a fume hood, and air-dry to remove most of the solvent to obtain the prepreg;

[0110] 5) Cutting, stacking, placing in a hot press, and preparing a polyimide thermosetting resin-based carbon fiber composite laminate according to the following hot pressing process:

[0111] (a) Room temperature 25°C to 150°C, heating rate 3°C / min (42 min), keep warm for 30 min;

[0112] (b) 150°C to 200°C, heating rate 0.5°C / min (100 min), holding time 120 min;

[0113] (c) 200°C to 240°C, heating rate 3°C / min (14 min), no heat preservation, and applying a pressure of 1.5-2 MPa when the temperature reaches 244°C;

[0114] (d) 240℃ to 320℃, heating rate 2℃ / min, keep warm for 2h. During this period, the pressure will increase with the temperature increase. Observe the pressure change and reduce the pressure appropriately to maintain the pressure at 1.5-2MPa;

[0115] (e) After the 320℃ insulation is completed, the pressure is released to normal pressure.

[0116] The performance tests of the four groups of polyimide thermosetting resin-based carbon fiber composite laminates prepared in Example 1 are carried out, and the results are shown in Table 1. Sample 1 in Table 1 is a sample obtained from the monomer mixture solution of the toughened modified polyimide thermosetting resin prepared in Comparative Example 1, sample 2 is a sample obtained from the monomer mixture solution of the toughened modified polyimide thermosetting resin prepared in Example 2, sample 3 is a sample obtained from the monomer mixture solution of the toughened modified polyimide thermosetting resin prepared in Example 1, and sample 4 is a sample obtained from the monomer mixture solution of the toughened modified polyimide thermosetting resin prepared in Example 3.

[0117] The test results show that the introduction of toughened and modified polyimide thermosetting resin significantly improves the impact strength of polyimide thermosetting resin-based carbon fiber composite laminates. Compared with ordinary polyimide thermosetting resins, the impact strength can be increased by 70%.

[0118] Table 1 Characterization results of physical and mechanical properties of resin-based carbon fiber composite materials prepared from polyimide thermosetting resins prepared in Examples 1 to 3 and Comparative Example 1

[0119]

[0120]

[0121] It can be seen from Table 1 that the introduction of long alkane chain organic diamine (such as Z10Z) significantly improves the impact strength of BNT50, and the impact strength of the resin-based carbon fiber composite material obtained by the BNT50-Z107 product prepared in Example 1 reaches the maximum, which is 15.30 kJ / m 2 Compared with the BNT50 prepared in Comparative Example 2, the resin-based carbon fiber composite material obtained was improved by 70.8%.

[0122] It can be seen from the above embodiments that the present invention, by introducing a long alkyl chain terminal amino monomer into the main molecular chain of the polyimide thermosetting resin, embeds the flexible unit into a cross-linked three-dimensional network structure, and can effectively improve the impact toughness of the polyimide thermosetting resin while maintaining a high glass transition temperature of the resin material. At the same time, the polyimide thermosetting resin of the present invention does not use MDA monomer and methanol solution, thereby avoiding the harm and pollution of the resin to the human body and the environment. Finally, the thermosetting resin used in the present invention uses only a one-step esterification reaction, and only one reactor can be used to complete the synthesis of the resin. The esterification reaction temperature is low, the process is simple, energy consumption is saved, and costs are reduced.

[0123] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A toughened and modified polyimide thermosetting resin, characterized in that: It has the structure shown in formula I: In formula I: Ar1 is a residue of an aromatic diamine monomer, Ar1 is selected from one or more of a phenyl group, a biphenyl group, a substituted biphenyl group, a diphenyl ether group and a triphenyl ether group, and the substituent of the substituted biphenyl group is a C1-10 alkyl group or a halogen-substituted C1-10 alkyl group; Ar2 is a residue of an aromatic dianhydride monomer, and Ar2 is selected from one or more of a phenyl group, a biphenyl group, a diphenyl ether group, and a benzophenone group; Ar3 is a residue of a long alkane chain diamine monomer, and the number of carbon atoms in Ar3 is 5 to 10; n is a positive integer of 1-5, and m is a positive integer of 1-3.

2. The toughened and modified polyimide thermosetting resin according to claim 1, characterized in that: Ar1 is selected from any one or more of the structures represented by the following formula (1) to formula (7):

3. The toughened and modified polyimide thermosetting resin according to claim 1, characterized in that: Ar2 is selected from any one or more of the structures shown in the following formula (8) to formula (14):

4. The toughened and modified polyimide thermosetting resin according to claim 1, characterized in that: The long alkane chain diamine monomer is selected from one or more of 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane and 1,10-diaminodecane.

5. The toughened and modified polyimide thermosetting resin according to any one of claims 1 to 4, characterized in that: The toughened and modified polyimide thermosetting resin has a glass transition temperature of 300 to 420° C. and an impact toughness of 6.82 to 8.34 kJ / m 2 .

6. The method for preparing the monomer mixture solution of toughened and modified polyimide thermosetting resin according to any one of claims 1 to 5, characterized in that: The following steps are involved: The aromatic dianhydride monomer, the reactive end-capping agent and the alcohol solvent are mixed to carry out an esterification reaction to obtain an esterification solution; The esterification solution, aromatic diamine monomer, long alkane chain diamine monomer and alcohol solvent are mixed to obtain the monomer mixture solution of the toughened and modified polyimide thermosetting resin.

7. The preparation method according to claim 6, characterized in that: The reactive end-capping agent is nadic anhydride; the mass ratio of the aromatic dianhydride monomer to the reactive end-capping agent is 100:(20-55); The mass ratio of the aromatic dianhydride monomer to the aromatic diamine monomer is 100:(80-130); The mass ratio of the aromatic dianhydride monomer to the long alkane chain diamine monomer is 100:(5-10).

8. The preparation method according to claim 6, characterized in that: The temperature of the esterification reaction is 60-100° C., and the time is 2-6 hours.

9. The method for preparing the toughened and modified polyimide thermosetting resin molding powder according to any one of claims 1 to 5, characterized in that: The following steps are involved: A monomer mixture solution of the toughened and modified polyimide thermosetting resin according to any one of claims 1 to 5 is obtained according to the preparation method according to any one of claims 6 to 8; The monomer mixture solution of the toughened and modified polyimide thermosetting resin is sequentially concentrated and heat-treated to obtain molding powder of the toughened and modified polyimide thermosetting resin.

10. Use of the toughened modified polyimide thermosetting resin according to any one of claims 1 to 5, or the monomer mixture solution of the toughened modified polyimide thermosetting resin prepared by the preparation method according to any one of claims 6 to 8, or the molding powder of the toughened modified polyimide thermosetting resin prepared by the preparation method according to claim 9 in pure resin molded parts or resin-based carbon fiber composite materials.

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