1. The rigid polyimide foam material is characterized by comprising a structure that epoxy groups after ring opening are grafted into polyimide chains.

2. The rigid polyimide foam of claim 1, wherein said epoxy groups are provided by an epoxy resin;

the hard polyimide foam material contains a structure formed by condensation polymerization of epoxy groups with active two ends and carboxyl in a dianhydride esterification ring-opening molecular structure and a five-membered ring structure formed by the epoxy groups with active two ends and isocyanic acid radical in a polymer molecular chain;

the rigid polyimide foam material is formed by bonding an epoxy resin polymer and a polyimide polymer through a chemical bond;

the hard polyimide foam material is an epoxy resin reinforced hard polyimide foam material.

3. The rigid polyimide foam according to claim 2, wherein the epoxy resin has a structure according to formula (I):

the rigid polyimide foam material has a structure shown in formulas (II) and (III):

wherein R is one or more of formulas (2) to (7);

the hard polyimide foam material is provided with a graft type interpenetrating network system formed by bonding epoxy resin polymer chains with polyimide polymer chains and randomly penetrating and intertwining the epoxy resin polymer chains and the polyimide polymer chains;

the density of the hard polyimide foam material is 30-150 kg/m³；

The tensile strength of the rigid polyimide foam material is 0.4-2 MPa.

4. The hard polyimide foam material is characterized by comprising the following raw materials in parts by weight:

5. the rigid polyimide foam according to claim 4, wherein the aromatic dianhydride has a structure represented by formula (1):

wherein R is one or more of formulas (2) to (7);

6. the rigid polyimide foam material of claim 4, wherein the polymeric MDI comprises one or more of PM-200, 44V20, M20S, 5005, MR-200, M200, PAPI27, and PAPI 13;

the functionality of the polymeric MDI is 2.1-3.9;

the solvent comprises one or more of DMF, DMAC, NMP and DMSO;

the low molecular alcohol comprises CH₃OH、C₂H₅OH and C₃H₇One or more of OH;

the foam stabilizer comprises one or more of OFX-0193, OFX-8417, OFX-8468, L550, L540, L580, L668 and L5333.

7. The rigid polyimide foam according to claim 4, wherein the catalyst comprises one or more of triethylenediamine, N-methylmorpholine, N '-diethylpiperazine, N' -diethyl-2-methylpiperazine, N-2-hydroxypropyl dimethylmorpholine, triethanolamine, N-dimethylethanolamine, stannous octoate, dibutyltin dilaurate, dibutyltin diacetate, potassium isooctanoate, potassium oleate, and cobalt isooctanoate;

the foaming agent comprises one or more of acetone, water, methanol, ethanol, cyclopentane and isopentane;

the epoxy resin comprises one or more of E54, E51, E44, E42, E31, R130, R139, R140, R144, R301, DER321, DER330, and DER 337;

the epoxy value of the epoxy resin is 0.2-0.6;

the rigid polyimide foam material has a closed cell structure;

the opening rate of the hard polyimide foam material is 1-10%;

the aperture of the rigid polyimide foam material is 80-300 microns.

8. A method for producing the rigid polyimide foam according to any one of claims 1 to 3 or the rigid polyimide foam according to any one of claims 4 to 7, comprising the steps of:

1) reacting aromatic dianhydride, a solvent and low molecular alcohol to obtain a reaction solution;

2) reacting the reaction solution obtained in the step with epoxy resin again to obtain a prepolymer solution;

3) and mixing the prepolymer solution, the catalyst, the foaming agent and the foam stabilizer, adding polymeric MDI, continuously mixing, foaming and molding in a mold, and finally curing to obtain the hard polyimide foam material.

9. The production method according to claim 8, wherein the reaction means includes a reflux reaction;

the reaction temperature is 40-90 ℃;

the reaction time is 2.5-6 h;

the temperature of the secondary reaction is 70-90 ℃;

the secondary reaction time is 0.5-2 h;

the continuous mixing is high speed mixing.

10. The preparation method according to claim 8, wherein the rotation speed of the continuous mixing is 500-2000 rpm;

the time for continuously mixing is 8-25 s;

the step of standing is also included after the foaming molding;

the standing time is 12-25 min;

the curing temperature is 180-250 ℃;

the curing time is 2-5 h.

Background

Polyimide foam is produced in the 60 s of the 20 th century, and compared with other traditional polymer foams, the polyimide foam has the advantages of heat insulation, shock absorption, noise reduction and the like shared by foams, and has the specific performances of high and low temperature resistance (-250-450 ℃), non-combustibility, radiation resistance, low smoke generation rate, less decomposition and release of toxic gases and the like. Polyimide foam is soft open-cell foam in general, and is increasingly used as heat insulation and sound absorption materials in a plurality of high-tech fields such as aerospace, space stations, naval vessels, nuclear power stations and the like in recent years. With the development of high and new technologies such as aerospace and the like, higher requirements are put forward on the performance of polyimide foam, good heat insulation and heat preservation effects are required, and meanwhile, the polyimide foam also has the effect of bearing structural load, so that the requirements on the hard high-pressure-resistant polyimide foam are urgent.

Typical methods of reinforcing polyimide foams are fiber reinforcement, particulate reinforcement, and the like. The phenomenon that bubbles exist in a product and foams are unstable in the post-treatment process is easily caused by fiber reinforcement, and the viscosity of a foaming system is easily increased due to particle reinforcement, so that foaming is difficult.

Therefore, how to find a suitable polyimide foam modification method solves the problems existing in the existing reinforced polyimide foam, has great significance for better improving the mechanical property of the polyimide foam and widening the foam application field, and is one of the focuses of various research and development manufacturers and a front-line researcher.

Disclosure of Invention

In view of the above, the technical problem to be solved by the present invention is to provide a rigid polyimide foam material and a preparation method thereof, and in particular, to an epoxy resin reinforced rigid polyimide foam material and a preparation method thereof. And the process is simple and easy to control, and is favorable for realizing industrial continuous production.

The invention provides a rigid polyimide foam material which contains a structure that epoxy groups after ring opening are connected into a polyimide chain.

Preferably, the epoxy groups are provided by an epoxy resin;

the hard polyimide foam material contains a structure formed by condensation polymerization of epoxy groups with active two ends and carboxyl in a dianhydride esterification ring-opening molecular structure and a five-membered ring structure formed by the epoxy groups with active two ends and isocyanic acid radical in a polymer molecular chain;

the rigid polyimide foam material is formed by bonding an epoxy resin polymer and a polyimide polymer through a chemical bond;

the hard polyimide foam material is an epoxy resin reinforced hard polyimide foam material.

Preferably, the epoxy resin has a structure shown in formula (I):

the rigid polyimide foam material has a structure shown in formulas (II) and (III):

wherein R is one or more of formulas (2) to (7);

the hard polyimide foam material is provided with a graft type interpenetrating network system formed by bonding epoxy resin polymer chains with polyimide polymer chains and randomly penetrating and intertwining the epoxy resin polymer chains and the polyimide polymer chains;

the density of the hard polyimide foam material is 30-150 kg/m³；

The tensile strength of the rigid polyimide foam material is 0.4-2 MPa.

The invention provides a rigid polyimide foam material which comprises the following raw materials in parts by weight:

15-40 parts by weight of aromatic dianhydride;

10-45 parts by weight of polymeric MDI;

20-50 parts by weight of a solvent;

1-5.0 parts by weight of low molecular alcohol;

6-18 parts of a foam stabilizer;

0.5-4 parts by weight of a catalyst;

4-16 parts by weight of a foaming agent;

5-15 parts of epoxy resin.

Preferably, the aromatic dianhydride has a structure represented by formula (1):

wherein R is one or more of formulas (2) to (7);

preferably, the polymeric MDI comprises one or more of PM-200, 44V20, M20S, 5005, MR-200, M200, PAPI27 and PAPI 13;

the functionality of the polymeric MDI is 2.1-3.9;

the solvent comprises one or more of DMF, DMAC, NMP and DMSO;

the low molecular alcohol comprises CH₃OH、C₂H₅OH and C₃H₇One of OHOr a plurality thereof;

the foam stabilizer comprises one or more of OFX-0193, OFX-8417, OFX-8468, L550, L540, L580, L668 and L5333.

Preferably, the catalyst comprises one or more of triethylenediamine, N-methylmorpholine, N '-diethylpiperazine, N' -diethyl-2-methylpiperazine, N-2-hydroxypropyl dimethylmorpholine, triethanolamine, N-dimethylethanolamine, stannous octoate, dibutyltin dilaurate, dibutyltin diacetate, potassium isooctanoate, potassium oleate and cobalt isooctanoate;

the foaming agent comprises one or more of acetone, water, methanol, ethanol, cyclopentane and isopentane;

the epoxy resin comprises one or more of E54, E51, E44, E42, E31, R130, R139, R140, R144, R301, DER321, DER330, and DER 337;

the epoxy value of the epoxy resin is 0.2-0.6;

the rigid polyimide foam material has a closed cell structure;

the opening rate of the hard polyimide foam material is 1-10%;

the aperture of the rigid polyimide foam material is 80-300 microns.

The invention provides a rigid polyimide foam material as defined in any of the above technical schemes or a preparation method of the rigid polyimide foam material as defined in any of the above technical schemes, comprising the following steps:

1) reacting aromatic dianhydride, a solvent and low molecular alcohol to obtain a reaction solution;

2) reacting the reaction solution obtained in the step with epoxy resin again to obtain a prepolymer solution;

3) and mixing the prepolymer solution, the catalyst, the foaming agent and the foam stabilizer, adding polymeric MDI, continuously mixing, foaming and molding in a mold, and finally curing to obtain the hard polyimide foam material.

Preferably, the reaction mode comprises a reflux reaction;

the reaction temperature is 40-90 ℃;

the reaction time is 2.5-6 h;

the temperature of the secondary reaction is 70-90 ℃;

the secondary reaction time is 0.5-2 h;

the continuous mixing is high speed mixing.

Preferably, the rotation speed of the continuous mixing is 500-2000 rpm;

the time for continuously mixing is 8-25 s;

the step of standing is also included after the foaming molding;

the standing time is 12-25 min;

the curing temperature is 180-250 ℃;

the curing time is 2-5 h.

The invention provides a rigid polyimide foam material which contains a structure that epoxy groups after ring opening are connected into a polyimide chain. Compared with the prior art, the invention aims at the existing fiber-reinforced and particle-reinforced polyimide foam. The foaming process has the problems of unstable foam in the bubble and post-treatment process, easy rapid increase of the viscosity of the foaming system, difficult foaming and the like. The invention particularly adopts the polymer interpenetrating network enhancing technology, is easier to control, can improve the dispersibility of different components in a blend system, stabilizes each phase, increases the network density, has affinity with phase interfaces, and can obviously improve the mechanical property of the material.

The invention creatively provides a hard polyimide foam material with a special structure, which adopts epoxy resin to reinforce the polyimide foam material, epoxy groups are connected into a polyimide chain structure after ring opening, active epoxy groups at two ends can carry out polycondensation reaction with carboxyl in a dianhydride esterification ring-opening molecular structure, and can also form a five-membered ring with isocyanic acid radical in a polymer molecular chain. The epoxy resin and the polyimide are combined through chemical bonds and are randomly penetrated and entangled with each other to form a graft type interpenetrating network system, so that the epoxy resin has good dispersibility and interface affinity in the polyimide system, a 'forced co-dissolution' synergistic effect is achieved, the problem of compatibility of the polymer system is effectively solved, the mechanical property of the polyimide foam is improved, and the method has important significance for widening the application field of the polyimide foam.

According to the rigid polyimide foam material provided by the invention, the interpenetrating network foam material is prepared from the epoxy resin and the polyimide, so that the mechanical property of the polyimide foam is greatly improved, and meanwhile, the excellent heat resistance is kept. And the process is simple and easy to control, and is favorable for realizing industrial continuous production.

Experimental results show that the density of the epoxy resin reinforced hard polyimide foam material prepared by the invention is 59kg/m³The compression strength is 0.915MPa, the tensile strength is 1.018MPa, the shear strength is 0.796MPa, the 5% thermal weight loss temperature is 334 ℃, and the comprehensive performance and the mechanical property are excellent.

Detailed Description

For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.

All of the starting materials of the present invention, without particular limitation as to their source, may be purchased commercially or prepared according to conventional methods well known to those skilled in the art.

All of the starting materials of the present invention are not particularly limited in their purity, and the present invention preferably employs purity requirements that are conventional in the art of analytically pure or rigid polyimide foam preparation.

All the raw materials, the marks and the acronyms thereof belong to the conventional marks and acronyms in the field, each mark and acronym is clear and definite in the field of related application, and the raw materials can be purchased from the market or prepared by a conventional method by the technical staff in the field according to the marks, the acronyms and the corresponding application.

The invention provides a rigid polyimide foam material which contains a structure that epoxy groups after ring opening are connected into a polyimide chain.

In the present invention, the epoxy group is preferably provided by an epoxy resin.

In the present invention, the rigid polyimide foam is preferably an epoxy resin reinforced rigid polyimide foam.

In the invention, in the rigid polyimide foam material, a structure formed by condensation polymerization of epoxy groups with active two ends and carboxyl in a dianhydride esterification ring-opening molecular structure and a five-membered ring structure formed by epoxy groups with active two ends and isocyanic acid radical in a polymer molecular chain are preferred.

In the present invention, the rigid polyimide foam is preferably formed by bonding an epoxy polymer and a polyimide polymer through a chemical bond.

In the present invention, the epoxy resin preferably has a structure represented by formula (I):

in the present invention, the rigid polyimide foam preferably has a structure as shown in formulas (II) and (III):

among them, the R is preferably one or more of formulae (2) to (7), more preferably formula (2), (3), (4), (5), (6) or (7).

In the present invention, the rigid polyimide foam preferably has a graft type interpenetrating network system in which epoxy resin polymer chains are bonded to polyimide polymer chains and are randomly through-entangled with each other.

In the present invention, the density of the rigid polyimide foam is preferably 30 to 150kg/m³More preferably 50 to 130kg/m³More preferably 70 to 110kg/m³。

In the present invention, the tensile strength of the rigid polyimide foam is preferably 0.4 to 2MPa, more preferably 0.6 to 1.8MPa, more preferably 0.8 to 1.6MPa, and more preferably 1.0 to 1.4 MPa.

The invention provides a rigid polyimide foam material which comprises the following raw materials in parts by weight:

15-40 parts by weight of aromatic dianhydride;

10-45 parts by weight of polymeric MDI;

20-50 parts by weight of a solvent;

1-5.0 parts by weight of low molecular alcohol;

6-18 parts of a foam stabilizer;

0.5-4 parts by weight of a catalyst;

4-16 parts by weight of a foaming agent;

5-15 parts of epoxy resin.

In the present invention, the aromatic dianhydride is preferably added in an amount of 15 to 40 parts by weight, more preferably 18 to 37 parts by weight, more preferably 21 to 34 parts by weight, and more preferably 24 to 30 parts by weight.

In the present invention, the aromatic dianhydride preferably has a structure represented by formula (1):

wherein R is preferably one or more of formulae (2) to (7), more preferably (2), (3), (4), (5), (6) or (7).

In the present invention, the polymeric MDI is preferably added in an amount of 10 to 45 parts by weight, more preferably 15 to 40 parts by weight, more preferably 20 to 35 parts by weight, and more preferably 25 to 30 parts by weight. The polymeric MDI preferably comprises one or more of PM-200, 44V20, M20S, 5005, MR-200, M200, PAPI27 and PAPI13, more preferably PM-200, 44V20, M20S, 5005, MR-200, M200, PAPI27 or PAPI 13.

In the invention, the functionality of the polymeric MDI is preferably 2.1-3.9, more preferably 2.5-3.4, and more preferably 2.9-3.0.

In the present invention, the solvent is preferably added in an amount of 20 to 50 parts by weight, more preferably 25 to 45 parts by weight, and still more preferably 30 to 40 parts by weight.

In the present invention, the solvent preferably includes one or more of DMF, DMAC, NMP, and DMSO, more preferably DMF, DMAC, NMP, or DMSO.

In the present invention, the low molecular alcohol is preferably added in an amount of 1 to 5.0 parts by weight, more preferably 1.5 to 4.5 parts by weight, more preferably 2.0 to 4.0 parts by weight, and more preferably 2.5 to 3.5 parts by weight.

In the present invention, the low molecular alcohol preferably includes CH₃OH、C₂H₅OH and C₃H₇One or more of OH, more preferably CH₃OH、C₂H₅OH or C₃H₇OH。

In the invention, the addition amount of the foam stabilizer is preferably 6 to 18 parts by weight, more preferably 8 to 16 parts by weight, and still more preferably 10 to 14 parts by weight.

In the present invention, the foam stabilizer preferably comprises one or more of OFX-0193, OFX-8417, OFX-8468, L550, L540, L580, L668 and L5333, and more preferably OFX-0193, OFX-8417, OFX-8468, L550, L540, L580, L668 or L5333.

In the present invention, the amount of the catalyst added is preferably 0.5 to 4 parts by weight, more preferably 1 to 3.5 parts by weight, more preferably 1.5 to 3.0 parts by weight, and more preferably 2.0 to 2.5 parts by weight.

In the present invention, the catalyst preferably includes one or more of triethylenediamine, N-methylmorpholine, N '-diethylpiperazine, N' -diethyl-2-methylpiperazine, N-2-hydroxypropyldimethylmorpholine, triethanolamine, N-dimethylethanolamine, stannous octoate, dibutyltin dilaurate, dibutyltin diacetate, potassium isooctanoate, potassium oleate and cobalt isooctanoate, more preferably triethylenediamine, N-methylmorpholine, N '-diethylpiperazine, N' -diethyl-2-methylpiperazine, N-2-hydroxypropyldimethylmorpholine, triethanolamine, N-dimethylethanolamine, stannous octoate, dibutyltin dilaurate, dibutyltin diacetate, iron oxide, zinc oxide, Potassium isooctanoate, potassium oleate or cobalt isooctanoate.

In the present invention, the amount of the blowing agent added is preferably 4 to 16 parts by weight, more preferably 6 to 14 parts by weight, and still more preferably 8 to 12 parts by weight.

In the present invention, the blowing agent preferably includes one or more of acetone, water, methanol, ethanol, cyclopentane and isopentane, more preferably acetone, water, methanol, ethanol, cyclopentane or isopentane.

In the present invention, the epoxy resin is preferably added in an amount of 5 to 15 parts by weight, more preferably 7 to 13 parts by weight, and still more preferably 9 to 11 parts by weight.

In the present invention, the epoxy resin preferably includes one or more of E54, E51, E44, E42, E31, R130, R139, R140, R144, R301, DER321, DER330, and DER337, and more preferably E54, E51, E44, E42, E31, R130, R139, R140, R144, R301, DER321, DER330, or DER 337.

In the present invention, the epoxy value of the epoxy resin is preferably 0.2 to 0.6, more preferably 0.25 to 0.55, more preferably 0.3 to 0.5, and more preferably 0.35 to 0.45.

In the present invention, the rigid polyimide foam preferably has a closed cell structure.

In the present invention, the rigid polyimide foam preferably has an open cell content of 1% to 10%, more preferably 3% to 8%, and still more preferably 5% to 6%.

In the invention, the aperture of the rigid polyimide foam material is preferably 80-300 μm, more preferably 120-260 μm, and more preferably 160-220 μm.

The invention also provides a rigid polyimide foam material as defined in any one of the above technical requirements or a method for preparing a rigid polyimide foam material as defined in any one of the above technical requirements, comprising the steps of:

1) reacting aromatic dianhydride, a solvent and low molecular alcohol to obtain a reaction solution;

2) reacting the reaction solution obtained in the step with epoxy resin again to obtain a prepolymer solution;

3) and mixing the prepolymer solution, the catalyst, the foaming agent and the foam stabilizer, adding polymeric MDI, continuously mixing, foaming and molding in a mold, and finally curing to obtain the hard polyimide foam material.

The method comprises the steps of firstly reacting aromatic dianhydride, a solvent and low molecular alcohol to obtain a reaction solution.

In the present invention, the reaction mode preferably includes a reflux reaction.

In the invention, the reaction temperature is preferably 40-90 ℃, more preferably 50-80 ℃, and more preferably 60-70 ℃.

In the invention, the reaction time is preferably 2.5-6 h, more preferably 3-5.5 h, more preferably 3.5-5.0 h, and more preferably 4.0-4.5 h.

In the present invention, the reaction solution is preferably a transparent solution.

The invention further reacts the reaction liquid obtained in the step with epoxy resin again to obtain prepolymer solution.

In the invention, the temperature of the secondary reaction is preferably 70-90 ℃, more preferably 74-86 ℃, and more preferably 78-82 ℃.

In the invention, the time for the secondary reaction is preferably 0.5 to 2 hours, more preferably 0.8 to 1.7 hours, and more preferably 1.1 to 1.4 hours.

In the present invention, it is preferable to further include a temperature reduction step after the re-reaction. Specifically, the temperature is preferably reduced to room temperature. Wherein the room temperature is preferably 5-35 ℃.

Finally, mixing the prepolymer solution, the catalyst, the foaming agent and the foam stabilizer, adding polymeric MDI, continuously mixing, foaming and molding in a mold, and finally curing to obtain the hard polyimide foam material.

In the present invention, the continuous mixing is preferably high-speed mixing.

In the invention, the rotation speed of the continuous mixing is preferably 500-2000 rpm, more preferably 750-1750 rpm, and more preferably 1000-1500 rpm.

In the invention, the time for continuously mixing is preferably 8-25 s, more preferably 10-23 s, more preferably 13-20 s, and more preferably 15-18 s.

In the present invention, the temperature of the foam molding is preferably room temperature. Wherein the room temperature is preferably 5-35 ℃.

In the present invention, the foaming preferably includes a standing step after the foaming.

In the invention, the standing time is preferably 12-25 min, more preferably 14-23 min, more preferably 16-21 min, and more preferably 18-19 min.

In the invention, the curing temperature is preferably 180-250 ℃, more preferably 190-240 ℃, more preferably 200-230 ℃, and more preferably 210-220 ℃.

In the invention, the curing time is preferably 2-5 h, more preferably 2.5-4.5 h, and more preferably 3-4 h.

The invention is a complete and refined integral preparation process, better ensures the performance and the structure of the epoxy resin reinforced rigid polyimide foam material, and the preparation method of the rigid polyimide foam material can specifically comprise the following steps:

(1) adding aromatic dianhydride into a solvent, and then adding low molecular alcohol for reflux reaction at the temperature of 40-90 ℃ for 2.5-6 hours to obtain a transparent solution;

(2) adding epoxy resin into the transparent solution for further reaction at the temperature of 70-90 ℃ for 0.5-2 h to obtain a prepolymer solution;

(3) cooling the prepolymer solution to room temperature, adding a catalyst, a foaming agent and a foam stabilizer, and uniformly stirring to obtain a mixed solution;

(4) mixing the mixed solution and the polymeric MDI at a high speed of 500-2000 rpm for 8-25 s, injecting into a mold, foaming and molding at room temperature, and standing for 12-25 min;

(5) and finally, baking and curing the foam at the temperature of 180-250 ℃ for 2-5 h.

The invention can realize interpenetrating network systems of various forms of mutual random through entanglement by controlling the addition amount and reaction conditions of the epoxy resin, in the reaction process, the aromatic dianhydride is firstly esterified and opened in a ring manner, when ester which does not react with the epoxy resin exists, isocyanate in a later-stage polymer chain does not react with the epoxy resin, and then the interpenetrating network system formed by the mutual random through entanglement and formed by the conventional polyimide and the epoxy resin grafted polyimide is obtained. In the reaction process, when epoxy resin which does not participate in the reaction exists, an interpenetrating network system formed by the physical interpenetration of the epoxy resin and the mutual random interpenetration entanglement formed by the epoxy resin grafted polyimide is formed in a polymer system; an interpenetrating network system formed by the mutual random interpenetrating entanglement of the three components of the conventional polyimide and the epoxy resin grafted polyimide and the physical interpenetrating of the epoxy resin can be formed.

The invention provides an epoxy resin reinforced hard polyimide foam material and a preparation method thereof. According to the rigid polyimide foam material with the special structure, the epoxy resin reinforced polyimide foam material is adopted, epoxy groups are connected into a polyimide chain structure after being subjected to ring opening, active epoxy groups at two ends can be subjected to condensation polymerization with carboxyl in a dianhydride esterification ring-opening molecular structure, and can also form a five-membered ring with isocyanic acid radical in a polymer molecular chain. The epoxy resin and the polyimide are combined through chemical bonds and are randomly penetrated and entangled with each other to form a graft type interpenetrating network system, so that the epoxy resin has good dispersibility and interface affinity in the polyimide system, a 'forced co-dissolution' synergistic effect is achieved, the problem of compatibility of the polymer system is effectively solved, the mechanical property of the polyimide foam is improved, and the method has important significance for widening the application field of the polyimide foam.

According to the rigid polyimide foam material provided by the invention, the interpenetrating network foam material is prepared from the epoxy resin and the polyimide, so that the mechanical property of the polyimide foam is greatly improved, and meanwhile, the excellent heat resistance is kept. And the process is simple and easy to control, and is favorable for realizing industrial continuous production.

Experimental results show that the density of the epoxy resin reinforced hard polyimide foam material prepared by the invention is 59kg/m³The compression strength is 0.915MPa, the tensile strength is 1.018MPa, the shear strength is 0.796MPa, the 5% thermal weight loss temperature is 334 ℃, and the comprehensive performance and the mechanical property are excellent.

For further illustration of the present invention, a rigid polyimide foam and a method for preparing the same according to the present invention will be described in detail with reference to the following examples, but it should be understood that the present invention is not limited to the following examples, but the present invention is not limited to the following examples.

Example 1

(1) 22 parts of PMDA are added to 38 parts of DMAC, and 1.8 parts of CH are added₃Carrying out OH reflux reaction at 70 ℃ for 4h to obtain a transparent solution;

(2) adding 5 parts of E44 into the transparent solution for further reaction at 80 ℃ for 1.5 hours to obtain a prepolymer solution;

(3) cooling the prepolymer solution to room temperature, adding 0.3 part of triethylene diamine, 0.5 part of N, N-dimethylethanolamine, 0.8 part of stannous octoate, 6 parts of water and 8 parts of OFX-8417, and uniformly stirring to obtain a mixed solution;

(4) mixing the mixed solution with 24 parts of M20S at 1200rpm for 15s, injecting into a mold, foaming at room temperature, and standing for 15 min;

(5) finally, the foam is baked and cured at the temperature of 210 ℃ for 3.5 hours.

Example 2

(1) 22 parts of PMDA are added to 38 parts of DMAC, and 1.8 parts of CH are added₃Carrying out OH reflux reaction at 70 ℃ for 4h to obtain a transparent solution;

(2) adding 8 parts of E44 into the transparent solution for further reaction at 80 ℃ for 1.5 hours to obtain a prepolymer solution;

(3) cooling the prepolymer solution to room temperature, adding 0.3 part of triethylene diamine, 0.5 part of N, N-dimethylethanolamine, 0.8 part of stannous octoate, 6 parts of water and 8 parts of OFX-8417, and uniformly stirring to obtain a mixed solution;

(4) mixing the mixed solution with 24 parts of M20S at 1200rpm for 15s, injecting into a mold, foaming at room temperature, and standing for 15 min;

(5) finally, the foam is baked and cured at the temperature of 210 ℃ for 3.5 hours.

Example 3

(1) 22 parts of PMDA are added to 38 parts of DMAC, and 1.8 parts of CH are added₃Carrying out OH reflux reaction at 70 ℃ for 4h to obtain a transparent solution;

(2) adding 12 parts of E44 into the transparent solution for further reaction at 80 ℃ for 1.5 hours to obtain a prepolymer solution;

(3) cooling the prepolymer solution to room temperature, adding 0.3 part of triethylene diamine, 0.5 part of N, N-dimethylethanolamine, 0.8 part of stannous octoate, 6 parts of water and 8 parts of OFX-8417, and uniformly stirring to obtain a mixed solution;

(4) mixing the mixed solution with 24 parts of M20S at 1200rpm for 15s, injecting into a mold, foaming at room temperature, and standing for 15 min;

(5) finally, the foam is baked and cured at the temperature of 210 ℃ for 3.5 hours.

Example 4

(1) 22 parts of PMDA are added to 38 parts of DMAC, and 1.8 parts of CH are added₃OH reflux reaction at 70 deg.C for 4 hr to obtain methanolA clear solution;

(2) adding 5 parts of E31 into the transparent solution for further reaction at 80 ℃ for 1.5 hours to obtain a prepolymer solution;

(3) cooling the prepolymer solution to room temperature, adding 0.3 part of triethylene diamine, 0.5 part of N, N-dimethylethanolamine, 0.8 part of stannous octoate, 6 parts of water and 8 parts of OFX-8417, and uniformly stirring to obtain a mixed solution;

(4) mixing the mixed solution with 24 parts of M20S at 1200rpm for 15s, injecting into a mold, foaming at room temperature, and standing for 15 min;

(5) finally, the foam is baked and cured at the temperature of 210 ℃ for 3.5 hours.

Example 5

(1) 22 parts of PMDA are added to 38 parts of DMAC, and 1.8 parts of CH are added₃Carrying out OH reflux reaction at 70 ℃ for 4h to obtain a transparent solution;

(2) adding 5 parts of E51 into the transparent solution for further reaction at 80 ℃ for 1.5 hours to obtain a prepolymer solution;

(3) cooling the prepolymer solution to room temperature, adding 0.3 part of triethylene diamine, 0.5 part of N, N-dimethylethanolamine, 0.8 part of stannous octoate, 6 parts of water and 8 parts of OFX-8417, and uniformly stirring to obtain a mixed solution;

(4) mixing the mixed solution with 24 parts of M20S at 1200rpm for 15s, injecting into a mold, foaming at room temperature, and standing for 15 min;

(5) finally, the foam is baked and cured at the temperature of 210 ℃ for 3.5 hours.

Comparative example 1

(1) 22 parts of PMDA are added to 38 parts of DMAC, and 1.8 parts of CH are added₃Carrying out OH reflux reaction at 70 ℃ for 4h to obtain a transparent solution;

(2) cooling the transparent solution to room temperature, adding 0.3 part of triethylene diamine, 0.5 part of N, N-dimethylethanolamine, 0.8 part of stannous octoate, 6 parts of water and 8 parts of OFX-8417, and uniformly stirring to obtain a mixed solution;

(3) mixing the mixed solution with 24 parts of M20S at 1200rpm for 15s, injecting into a mold, foaming at room temperature, and standing for 15 min;

(4) finally, the foam is baked and cured at the temperature of 210 ℃ for 3.5 hours.

The performance of the epoxy resin reinforced hard polyimide foam material prepared in the examples 1 to 5 of the present invention and the polyimide foam material prepared in the comparative example 1 was tested.

The foam density test standard is GB/T6343-.

Referring to table 1, table 1 shows the results of performance tests of polyimide foams prepared in examples of the present invention and comparative examples.

TABLE 1

As can be seen from Table 1, the epoxy resins of the same type and different mass parts are selected for examples 1 to 3, and the epoxy resins of the same type and different mass parts are selected for examples 4 and 5. Compared with comparative example 1, the compression strength, the tensile strength and the shear strength of the examples 1 to 5 are obviously improved, and the heat resistance of the foam is slightly reduced. With the increase of the epoxy value in the epoxy resin, the grafting reaction between the polyimide and the epoxy resin between two phases is increased, so that a polymer system forms an intercrossed network structure, and the mechanical property of the foam is improved.

According to the invention, by selecting proper epoxy resin and adjusting the addition amount, the density of 59kg/m can be prepared³The hard polyimide foam material has the compression strength of 0.915MPa, the tensile strength of 1.018MPa, the shear strength of 0.796MPa, the 5 percent thermal weight loss temperature of 334 ℃, excellent comprehensive performance and outstanding mechanical property.

While the present invention has been described in detail with respect to an epoxy resin reinforced rigid polyimide foam and a method of making the same, the principles and embodiments of the present invention are described herein using specific examples, which are set forth only to facilitate an understanding of the methods and their core concepts, including the best mode, and to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention. The scope of the invention is defined by the claims and may include other embodiments that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.