Special high-temperature-resistant polyacrylamide foam material and preparation method thereof

Abstract

The invention discloses a high-temperature-resistant polyacrylamide foam material and a preparation method thereof. The high-temperature-resistant polyacrylamide foam material is prepared from carboxyl-containing acrylic monomers, cyano-containing acrylonitrile monomers, a linear polyimide polymer, a cosolvent, an initiator, a foaming agent, a cross-linking agent and other raw materials, and has excellent high-temperature resistance.

Description

Technical Field

[0001] The present application relates to the technical field of material preparation, and in particular to a high-temperature resistant polyacrylimide foam material and a preparation method and application thereof. Background Art

[0002] Polymethacrylimide (PMI) foam material is a cross-linked rigid closed-cell foam with outstanding structural stability and mechanical properties. It is currently the heat-resistant foam plastic with the highest strength and stiffness. It can achieve one-time co-curing of composite sandwich structures. It has an important position and wide application in many high-tech fields such as aerospace, rail transportation, radar antenna covers, wind power generation, ships, and new energy vehicles.

[0003] Most of the currently available PMI foam materials can only be used at 130-180°C. Although they meet most application environments, they are difficult to use in hot-pressing composites with special engineering materials. This is because the hot-pressing temperature of special engineering materials is mostly above 200°C, which greatly limits the application of currently available PMI in hot-pressing composite materials.

[0004] With the high-speed and lightweight development in the fields of aerospace and weapons, higher requirements are placed on foam materials, and their service environment is gradually evolving towards more extreme high temperatures. In this case, the defect that the conventional PMI foam cannot be used at high temperatures needs to be overcome urgently. Therefore, developing polyacrylimide foam materials that have both good mechanical properties and excellent high temperature resistance and can be used in the hot pressing molding process of special engineering materials has become one of the current research directions. Summary of the invention

[0005] The purpose of the present application is to provide a high-temperature resistant polyacrylimide foam material that can be used for special engineering materials, which can be used in the high-temperature special engineering material preparation process while maintaining the excellent mechanical properties of the foam.

[0006] Specifically, the present application provides a high temperature resistant polyacrylimide foam material, which includes the following raw materials: carboxyl-containing acrylic monomers, cyano-containing acrylonitrile monomers, linear polyimide polymers, cosolvents, initiators, foaming agents, and crosslinking agents, and the mass parts of the raw materials are arranged as follows:

[0007] 10-80 parts of carboxyl-containing acrylic monomer,

[0008] 10-80 parts of cyano-containing acrylonitrile monomers,

[0009] 1-45 parts of linear polyimide polymer,

[0010] Solvent 0.1-10 parts,

[0011] Initiator 0.1-20 parts,

[0012] 0.1-20 parts of foaming agent,

[0013] Crosslinking agent 0.1-20 parts.

[0014] Furthermore, the mass fraction of the raw materials is as follows:

[0015] 40-70 parts of carboxyl-containing acrylic monomer

[0016] 20-60 parts of cyano-containing acrylonitrile monomer

[0017] Linear polyimide polymer 5-35 parts

[0018] 1-5 parts of cosolvent,

[0019] Initiator 1-5 parts

[0020] Foaming agent 1-10 parts

[0021] 1-5 parts of crosslinking agent.

[0022] Furthermore, the linear polyimide polymer is a polymer of an aromatic diamine monomer and a dianhydride monomer, and the molar ratio of the aromatic diamine monomer to the dianhydride monomer is 1:1.

[0023] Furthermore, the linear polyimide polymer is prepared by the following method:

[0024] Mixing the dianhydride monomer and the alcohol solvent, heating and refluxing for 1-8 hours to form an alcohol solution of a diacid diester structure;

[0025] Adding the alcohol solution of the diacid diester structure to a mixed solution of an aromatic diamine monomer and an alcohol solvent, reacting for 1-7 hours under nitrogen protection to obtain a linear polyimide polymer solution;

[0026] The linear polyimide polymer solution is subjected to rotary evaporation, vacuum drying and pulverization to obtain the linear polyimide polymer.

[0027] Furthermore, the aromatic diamine monomer is selected from one or more of m-phenylenediamine, p-phenylenediamine, 1,5-naphthalene diamine, 4,4'-diaminodiphenyl ether, and 2,2-bis[4-(4-aminophenoxy)phenyl]propane; the alcohol solvent is selected from one or more of methanol, ethanol, and propanol; and the dianhydride monomer is selected from one or more of 1,2,4,5-pyromellitic anhydride, 2,3,3',4'-biphenyltetracarboxylic anhydride, bisphenol A diphenyl ether dianhydride, 3,3',4,4'-benzophenonetetracarboxylic anhydride, and pyromellitic anhydride.

[0028] Furthermore, the carboxyl-containing acrylic monomer is methacrylic acid, acrylic acid or a mixture thereof; the cyano-containing acrylonitrile monomer is methacrylonitrile, acrylonitrile or a mixture thereof.

[0029] Furthermore, the co-solvent is selected from one or more of NMP, DMAC, DMF, DMSO, toluene and chloroform, and more preferably DMAC or DMF.

[0030] Further, the initiator is selected from one or more of tert-amyl peroxyacetate, benzoyl peroxide, tert-butyl peroxy 2-ethylhexanoate, tert-amyl peroxybenzoate, tert-butyl peroxybenzoate, azobisisobutyronitrile and azoisobutylcyanamide, preferably tert-amyl peroxyacetate and benzoyl peroxide.

[0031] Furthermore, the foaming agent is selected from one or more of formamide, ethanol, propanol, isopropanol, tert-butanol and pentanol, preferably ethanol or propanol.

[0032] Furthermore, the cross-linking agent is selected from one or more of polyols, metal oxides, metal salt compounds, acrylamide, and methacrylamide.

[0033] Furthermore, the polyol is selected from glycerol, 1,4-butanediol, pentaerythritol or polyether polyol, the metal oxide is calcium oxide, magnesium oxide or zinc oxide, and the metal salt compound is methacrylate metal salt or acrylate metal salt.

[0034] More preferably, the cross-linking agent is zinc oxide or methacrylamide.

[0035] Furthermore, the present application also provides a method for preparing the high temperature resistant polyacrylimide foam material, which comprises the following steps:

[0036] A carboxyl-containing acrylic monomer, a cyano-containing acrylonitrile monomer, a linear polyimide polymer, a cosolvent, an initiator, a foaming agent and a crosslinking agent are stirred and mixed in proportion at room temperature for 1-8 hours to form a homogeneous solution;

[0037] The homogeneous solution is injected into a mold, and polymerized at 20-130° C. for 100-350 hours to obtain a polyimide foam prepolymer copolymer;

[0038] The polyimide foam prepolymer copolymer obtained above is heated and foamed in the range of 180-250° C. to obtain the high temperature resistant polyacrylimide foam material.

[0039] The present application also provides applications of the high temperature resistant polyacrylimide foam material in the fields of aviation, aerospace, military industry, high temperature resistant materials, etc.

[0040] Effects of the Invention

[0041] The polyacrylimide foam material provided by the present application adds a linear polyimide polymer to the raw material components of rigid foam plastics such as acrylic acid and acrylonitrile monomers, and adds a cosolvent to help the linear polyimide polymer dissolve better in the matrix material, inducing the formation of a semi-interpenetrating network copolymer structure, which can effectively improve the high temperature resistance and mechanical properties of the PMI foam material. At the same time, the linear polyimide polymer will undergo a cross-linking reaction at 200-230°C, which can increase the cross-linking degree of the system, increase the glass transition temperature of the PMI foam, and reduce the melt viscosity, thereby further improving the high temperature resistance of the PMI material. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is the DSC test chart of polyacrylimide foam material. DETAILED DESCRIPTION

[0043] The present application is further described in detail below in conjunction with specific implementation methods. The examples given are intended to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0044] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the functional differences of components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" are open-ended terms and should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present application, but the description is based on the general principles of the specification and is not intended to limit the scope of the present application. The scope of protection of the present application shall be determined by the attached claims.

[0045] The present application relates to a high temperature resistant polyacrylimide foam material, which comprises the following raw materials: carboxyl-containing acrylic monomers, cyano-containing acrylonitrile monomers, linear polyimide polymers, cosolvents, initiators, foaming agents and crosslinking agents. In a specific embodiment, the mass parts of the raw materials are arranged as follows:

[0046] 10-80 parts of carboxyl-containing acrylic monomer,

[0047] 10-80 parts of cyano-containing acrylonitrile monomers,

[0048] 1-45 parts of linear polyimide polymer,

[0049] Solvent 0.1-10 parts,

[0050] Initiator 0.1-20 parts,

[0051] 0.1-20 parts of foaming agent,

[0052] Crosslinking agent 0.1-20 parts.

[0053] In a preferred embodiment, the mass fractions of the raw materials are arranged as follows:

[0054] 40-70 parts of carboxyl-containing acrylic monomer,

[0055] 20-60 parts of cyano-containing acrylonitrile monomer

[0056] Linear polyimide polymer 5-35 parts

[0057] 1-5 parts of cosolvent,

[0058] Initiator 1-5 parts

[0059] Foaming agent 1-10 parts

[0060] 1-5 parts of crosslinking agent.

[0061] In a specific embodiment of the present application, the linear polyimide polymer is a polymer of an aromatic diamine monomer and a dianhydride monomer.

[0062] Aromatic diamine monomers are compounds containing two aromatic hydrocarbon rings and amino groups in the molecule, one of which is a bicyclic aromatic hydrocarbon composed of two benzene rings sharing one carbon atom. Its molecular structure is highly stable, has strong electron affinity and spatial interception ability, is not prone to oxidation or reduction reactions, and can be used to form many high-performance materials.

[0063] Dianhydride is an organic compound containing two acyl groups. It can be produced by the reaction of acyl chloride and anhydride and is often used as an acylating agent, reducing agent or exchange agent.

[0064] In a specific embodiment, the molar ratio of the aromatic diamine monomer to the dianhydride monomer is 2:1 to 1:2, for example, 2:1, 3:2, 4:3, 5:4, 1:1, 4:5, 3:4, 2:3, 1:2, preferably, the molar ratio is 1:1.

[0065] In a specific embodiment of the present application, the linear polyimide polymer can be prepared by the following method:

[0066] The dianhydride monomer is mixed with an alcohol solvent, and heated under reflux for 1-8 hours to form an alcohol solution with a diacid diester structure;

[0067] Adding the alcohol solution of the diacid diester structure to a mixed solution of an aromatic diamine monomer and an alcohol solvent, reacting for 1-7 hours under nitrogen protection to obtain a linear polyimide polymer solution;

[0068] The linear polyimide polymer solution is subjected to rotary evaporation, vacuum drying and pulverization to obtain the linear polyimide polymer.

[0069] In a specific embodiment, the aromatic diamine monomer is selected from one or more of m-phenylenediamine, p-phenylenediamine, 1,5-naphthalenediamine, 4,4'-diaminodiphenyl ether, and 2,2-bis[4-(4-aminophenoxy)phenyl]propane.

[0070] In a specific embodiment, the alcohol solvent is selected from one or more of methanol, ethanol and propanol.

[0071] In a specific embodiment, the dianhydride monomer is selected from one or more of 1,2,4,5-pyromellitic anhydride, 2,3,3',4'-biphenyltetracarboxylic anhydride, bisphenol A diphenyl ether dianhydride, 3,3',4,4'-benzophenonetetracarboxylic anhydride and pyromellitic anhydride.

[0072] In a preferred embodiment, the aromatic diamine monomer is p-phenylenediamine, the alcohol solvent is ethanol, and the dianhydride monomer is bisphenol A diphenyl ether dianhydride.

[0073] In the present application, the polymer formed by the aromatic diamine monomer and the dianhydride monomer is a polyimide polymer with a linear structure, which can be added to rigid foam materials such as PMI to further form a copolymer with an interpenetrating network structure, effectively improving the mechanical properties of the foam material at high temperatures.

[0074] In a specific embodiment of the present application, the carboxyl-containing acrylic monomer is acrylic acid, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, or a mixture thereof; the cyano-containing acrylonitrile monomer is methacrylonitrile, acrylonitrile or a mixture thereof.

[0075] In a specific embodiment of the present application, the co-solvent is selected from one or more of NMP, DMAC, DMF, DMSO, toluene, and chloroform. In a preferred embodiment, the solvent is DMAC or DMF.

[0076] DMAC is dimethylacetamide, the full name is N, N-dimethylacetamide (chemical formula: CH3C(O)N(CH3)2, abbreviated as DMAC or DMA, which is a non-protonic polar solvent.

[0077] NMP is N-methylpyrrolidone with the chemical formula of C5H9NO. It is miscible with water in any proportion, soluble in ether, acetone, esters, halogenated hydrocarbons, aromatic hydrocarbons and other organic solvents, and is completely miscible with almost all solvents.

[0078] DMF is N,N-dimethylformamide, with the chemical formula C3H7NO. It is not only a widely used chemical raw material, but also an excellent solvent with a wide range of uses. It can be mixed with water and most organic solvents at will, and has good solubility for a variety of organic and inorganic compounds.

[0079] In the embodiment of the present application, the addition of the co-solvent can make the linear polyimide polymer and the raw materials of the rigid foam more uniformly and fully mixed, which is conducive to forming a semi-interpenetrating network copolymer structure with better high temperature resistance.

[0080] In a specific embodiment of the present application, the initiator is selected from one or more of tert-amyl peroxyacetate, benzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-amyl peroxybenzoate, tert-butyl peroxybenzoate, azobisisobutyronitrile and azoisobutylcyanoformamide.

[0081] In a specific embodiment of the present application, the foaming agent is selected from one or more of formamide, ethanol, propanol, isopropanol, water, tert-butyl alcohol and amyl alcohol. In a preferred embodiment, it is ethanol or propanol.

[0082] In a specific embodiment of the present application, the cross-linking agent is selected from one or more of polyols, metal oxides, metal salt compounds, acrylamide, and methacrylamide.

[0083] In a specific embodiment, the polyols can be selected from glycerol, 1,4-butanediol, pentaerythritol or polyether polyols. The polyol crosslinking agent can increase the covalent bond level of the rigid foam raw material and form a stronger network polymer structure.

[0084] In a specific embodiment, the metal oxide is selected from calcium oxide, magnesium oxide or zinc oxide.

[0085] In a specific embodiment, the metal salt compound is selected from methacrylate metal salt or acrylate metal salt.

[0086] In a preferred embodiment, the cross-linking agent is zinc oxide or methacrylamide.

[0087] The present application also provides a method for preparing the high temperature resistant polyacrylimide foam material, which comprises the following steps:

[0088] A carboxyl-containing acrylic monomer, a cyano-containing acrylonitrile monomer, a linear polyimide polymer, a cosolvent, an initiator, a foaming agent and a crosslinking agent are stirred and mixed in proportion at room temperature for 1-8 hours to form a homogeneous solution;

[0089] The homogeneous solution is injected into a mold, and polymerized at 20-130° C. for 100-350 hours to obtain a polyimide foam prepolymer copolymer;

[0090] The polyimide foam prepolymer copolymer obtained above is heated and foamed in the range of 180-250° C. to obtain the high temperature resistant polyacrylimide foam material.

[0091] The present application also provides the application of the high temperature resistant polyacrylimide foam material in the fields of aviation, aerospace, military industry, high temperature resistant materials, etc., especially in the fields of high temperature resistant thermal insulation materials, high temperature resistant structural sandwich materials, high temperature resistant sound insulation materials or high temperature resistant wave-transmitting materials.

[0092] The present application prepares a PMI / PI rigid foam suitable for special high temperature resistance, with acrylic acid / methacrylic acid and acrylonitrile / methacrylonitrile as the main materials, adding linear polyimide polymer and cosolvent, initiator, foaming agent, crosslinking agent and mixing evenly, and performing free radical polymerization and foaming to prepare high temperature resistant PMI / PI foam. The foam produced has good mechanical properties and excellent high temperature resistance, and can be hot pressed in special engineering materials to further expand the application field of PMI foam.

[0093] Example

[0094] The present application provides a general and / or specific description of the materials and test methods used in the experiments. In the following examples, unless otherwise specified, % represents wt%, i.e., weight percentage. Among the reagents used, methacrylonitrile was purchased from Ningbo Jinfei Chemical Technology Co., Ltd., methacrylic acid was purchased from Ningbo Huajia Chemical Co., Ltd., and other reagents or instruments used without indicating the manufacturer are conventional reagent products or conventional experimental instruments that can be purchased commercially.

[0095] Example 1

[0096] (1) Preparation of linear polyimide polymers:

[0097] Add 52g of bisphenol A diphenyl ether dianhydride to 30g of ethanol, and heat under reflux for 5 hours to form an alcohol solution with a diacid diester structure;

[0098] The above solution was mixed with 11 g of p-phenylenediamine and 30 g of ethanol, and reacted for 3.5 hours under nitrogen protection to synthesize a linear polyimide polymer solution;

[0099] The linear polyimide polymer solution is subjected to rotary evaporation, vacuum drying and pulverization to obtain the linear polyimide polymer.

[0100] (2) 50 g of methacrylic acid, 20 g of methacrylonitrile, 15 g of the linear polyimide polymer prepared in step (1), 5 g of DMAC, 2 g of benzoyl peroxide, 6 g of propanol and 2 g of zinc oxide were stirred and mixed at room temperature for 7 hours to form a homogeneous solution;

[0101] (3) injecting the homogeneous solution into a mold, and polymerizing at 50-110° C. for 200 hours to obtain a polyimide foam prepolymer copolymer;

[0102] (4) The polyimide foam prepolymer copolymer obtained above is heated and foamed at a temperature within a range of 190-230° C. to obtain the high temperature resistant polyacrylimide foam material.

[0103] Example 2

[0104] (1) Preparation of linear polyimide polymers:

[0105] 21.8 g of pyromellitic dianhydride was added to 20 g of amyl alcohol, and the mixture was heated under reflux for 3.5 hours to form an alcohol solution with a diacid diester structure;

[0106] The above solution was mixed with 15.8 g of 1,5-naphthalenediamine and 15 g of amyl alcohol, and reacted for 6.5 hours under nitrogen protection to synthesize a linear polyimide polymer solution;

[0107] The linear polyimide polymer solution is subjected to rotary evaporation, vacuum drying and pulverization to obtain the linear polyimide polymer.

[0108] (2) 50 g of methacrylic acid, 20 g of methacrylonitrile, 15 g of the linear polyimide polymer prepared in step (1), 5 g of DMAC, 2 g of benzoyl peroxide, 6 g of propanol and 2 g of zinc oxide were stirred and mixed at room temperature for 3 hours to form a homogeneous solution;

[0109] (3) injecting the homogeneous solution into a mold, and polymerizing it at 20-100° C. for 180 hours to obtain a polyimide foam prepolymer copolymer;

[0110] (4) The polyimide foam prepolymer copolymer obtained above is heated and foamed at a temperature within a range of 190-230° C. to obtain the high temperature resistant polyacrylimide foam material.

[0111] Example 3

[0112] (1) Preparation of linear polyimide polymers:

[0113] Add 52g of bisphenol A diphenyl ether dianhydride to 30g of ethanol, and heat under reflux for 5 hours to form an alcohol solution with a diacid diester structure;

[0114] The above solution was mixed with 11 g of p-phenylenediamine and 30 g of ethanol, and reacted for 3.5 hours under nitrogen protection to synthesize a linear polyimide polymer solution;

[0115] The linear polyimide polymer solution is subjected to rotary evaporation, vacuum drying and pulverization to obtain the linear polyimide polymer.

[0116] (2) 50 g of acrylic acid, 20 g of acrylonitrile, 15 g of the linear polyimide polymer prepared in step (1), 5 g of NMP, 2 g of tert-amyl peroxyacetate, 6 g of tert-butyl alcohol and 2 g of calcium oxide were stirred and mixed at room temperature for 2.5 hours to form a homogeneous solution;

[0117] (3) injecting the homogeneous solution into a mold, and polymerizing it at 20-100° C. for 180 hours to obtain a polyimide foam prepolymer copolymer;

[0118] (4) The polyimide foam prepolymer copolymer obtained above is heated and foamed at a temperature within a range of 180-210° C. to obtain the high temperature resistant polyacrylimide foam material.

[0119] Example 4

[0120] (1) Preparation of linear polyimide polymers:

[0121] Add 52g of bisphenol A diphenyl ether dianhydride to 30g of ethanol, and heat under reflux for 5 hours to form an alcohol solution with a diacid diester structure;

[0122] The above solution was mixed with 11 g of p-phenylenediamine and 30 g of ethanol, and reacted for 3.5 hours under nitrogen protection to synthesize a linear polyimide polymer solution;

[0123] The linear polyimide polymer solution is subjected to rotary evaporation, vacuum drying and pulverization to obtain the linear polyimide polymer.

[0124] (2) 30 g of acrylic acid, 15 g of acrylonitrile, 40 g of the linear polyimide polymer prepared in step (1), 5 g of NMP, 2.5 g of tert-amyl peroxyacetate, 5 g of tert-butyl alcohol and 2.5 g of calcium oxide were stirred and mixed at room temperature for 2.5 hours to form a homogeneous solution;

[0125] (3) injecting the homogeneous solution into a mold, and polymerizing it at 20-100° C. for 180 hours to obtain a polyimide foam prepolymer copolymer;

[0126] (4) The polyimide foam prepolymer copolymer obtained above is heated and foamed at a temperature within a range of 180-210° C. to obtain the high temperature resistant polyacrylimide foam material.

[0127] Example 5

[0128] (1) Preparation of linear polyimide polymers:

[0129] 21.8 g of pyromellitic dianhydride was added to 20 g of amyl alcohol, and the mixture was heated under reflux for 3.5 hours to form an alcohol solution with a diacid diester structure;

[0130] The above solution was mixed with 15.8 g of 1,5-naphthalenediamine and 15 g of amyl alcohol, and reacted for 6.5 hours under nitrogen protection to synthesize a linear polyimide polymer solution;

[0131] The linear polyimide polymer solution is subjected to rotary evaporation, vacuum drying and pulverization to obtain the linear polyimide polymer.

[0132] (2) 30 g of acrylic acid, 15 g of acrylonitrile, 40 g of the linear polyimide polymer prepared in step (1), 5 g of NMP, 2.5 g of tert-amyl peroxyacetate, 5 g of tert-butyl alcohol and 2.5 g of calcium oxide were stirred and mixed at room temperature for 2.5 hours to form a homogeneous solution;

[0133] (3) injecting the homogeneous solution into a mold, and polymerizing it at 20-100° C. for 180 hours to obtain a polyimide foam prepolymer copolymer;

[0134] (4) The polyimide foam prepolymer copolymer obtained above is heated and foamed at a temperature within a range of 180-210° C. to obtain the high temperature resistant polyacrylimide foam material.

[0135] Comparative Example 1

[0136] (1) 60 g of methacrylic acid, 30 g of methacrylonitrile, 2 g of benzoyl peroxide, 6 g of propanol and 2 g of zinc oxide were stirred and mixed at room temperature for 7 hours to form a homogeneous solution;

[0137] (2) injecting the homogeneous solution into a mold, and polymerizing it at 50-110° C. for 200 hours to obtain a foamed prepolymer copolymer resin sheet;

[0138] (3) The foamed prepolymer copolymer resin sheet obtained above is heated and foamed at a temperature in the range of 190-230° C. to obtain a PMI material.

[0139] Comparative Example 2

[0140] (1) Preparation of linear polyimide polymers:

[0141] Add 52g of bisphenol A diphenyl ether dianhydride to 30g of ethanol, and heat under reflux for 5 hours to form an alcohol solution with a diacid diester structure;

[0142] The above solution was mixed with 11 g of p-phenylenediamine and 30 g of ethanol, and reacted for 3.5 hours under nitrogen protection to synthesize a linear polyimide polymer solution;

[0143] The linear polyimide polymer solution is subjected to rotary evaporation, vacuum drying and pulverization to obtain the linear polyimide polymer.

[0144] (2) 50 g of methacrylic acid, 25 g of methacrylonitrile, 15 g of the linear polyimide polymer prepared in step (1), 2 g of benzoyl peroxide, 6 g of propanol and 2 g of calcium oxide were stirred and mixed at room temperature for 7 hours to form a homogeneous solution;

[0145] (3) injecting the homogeneous solution into a mold, and polymerizing the solution at 50-110° C. for 200 hours to obtain a polyimide foam prepolymer copolymer resin sheet;

[0146] (4) The polyimide foam prepolymer copolymer resin sheet obtained above is heated and foamed in the range of 190-230° C. to obtain the high temperature resistant polyacrylimide foam material.

[0147] Experimental example: Determination of mechanical and temperature resistance properties

[0148] 1. The mechanical properties and high temperature resistance of the polyacrylimide foam materials obtained in the above examples and comparative examples were measured, and the results are shown in Table 1.

[0149] Among them, the apparent density is determined in accordance with "GB / T 6343-2009 Determination of apparent density of cellular plastics and rubber"; the heat deformation temperature is determined in accordance with "DIN 53424-1978 High temperature dimensional stability under bending stress and compressive stress"; the high temperature compression creep is determined in accordance with "GB / T 15048-94 Compression creep test method for rigid cellular plastics"; the tensile strength is determined in accordance with "ASTM-D638-2010 Plastic tensile test"; the compressive strength is determined in accordance with "GB / T 8813-2008 Determination of compression properties of rigid cellular plastics".

[0150] Table 1 Test results of mechanical and high temperature resistance properties of polyacrylimide foam materials

[0151]

[0152] 2. Thermal stability test was conducted on Example 1 and Comparative Examples 1 and 2. The DSC curve was obtained by using a Q100 differential scanning calorimeter (TA, USA). The test environment was a nitrogen atmosphere, the heating rate was 20°C / min, and the test temperature range was 40–280°C. The results are shown in Figure 1 It can be seen that compared with Comparative Examples 1 and 2, the endothermic peak of Example 1 shifts to the high temperature range, indicating that the construction of the polyacrylimide polymer semi-interpenetrating network system in Example 1 can give the foam better thermal stability.

[0153] It can be seen from the above experimental results that the polyacrylimide foam material provided in the embodiments of the present application has good mechanical properties and excellent high temperature resistance.

[0154] The above is only the preferred embodiment of the present application, and does not limit the present application in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present application without departing from the technical solution of the present application still falls within the protection scope of the technical solution of the present application.

Claims

1. A high temperature resistant polyacrylimide foam material, wherein: The invention comprises the following raw materials: carboxyl-containing acrylic monomer, cyano-containing acrylonitrile monomer, linear polyimide polymer, cosolvent, initiator, foaming agent, crosslinking agent, and the mass parts of the raw materials are as follows: 10-80 parts of carboxyl-containing acrylic monomer, 10-80 parts of cyano-containing acrylonitrile monomers, 1-45 parts of linear polyimide polymer, Solvent 0.1-10 parts, Initiator 0.1-20 parts, 0.1-20 parts of foaming agent, Crosslinking agent 0.1-20 parts.

2. The high temperature resistant polyacrylimide foam material according to claim 1, wherein: The linear polyimide polymer is a polymer of an aromatic diamine monomer and a dianhydride monomer, and the molar ratio of the aromatic diamine monomer to the dianhydride monomer is 1:

1.

3. The high temperature resistant polyacrylimide foam material according to claim 1 or 2, wherein: The linear polyimide polymer is prepared by the following method: Mixing the dianhydride monomer and the alcohol solvent, heating and refluxing for 1-8 hours to form an alcohol solution of a diacid diester structure; Adding the alcohol solution of the diacid diester structure to a mixed solution of an aromatic diamine monomer and an alcohol solvent, reacting for 1-7 hours under nitrogen protection to obtain a linear polyimide polymer solution; The linear polyimide polymer solution is subjected to rotary evaporation, vacuum drying and pulverization to obtain the linear polyimide polymer.

4. The high temperature resistant polyacrylimide foam material according to claim 3, wherein: The aromatic diamine monomer is selected from one or more of m-phenylenediamine, p-phenylenediamine, 1,5-naphthalene diamine, 4,4'-diaminodiphenyl ether, and 2,2-bis[4-(4-aminophenoxy)phenyl]propane; the alcohol solvent is selected from one or more of methanol, ethanol, and propanol; the dianhydride monomer is selected from one or more of 1,2,4,5-pyromellitic anhydride, 2,3,3',4'-biphenyltetracarboxylic anhydride, bisphenol A diphenyl ether dianhydride, 3,3',4,4'-benzophenonetetracarboxylic anhydride, and pyromellitic anhydride.

5. The high temperature resistant polyacrylimide foam material according to claim 1, wherein: The carboxyl-containing acrylic monomer is methacrylic acid, acrylic acid or a mixture thereof; the cyano-containing acrylonitrile monomer is methacrylonitrile, acrylonitrile or a mixture thereof.

6. The high temperature resistant polyacrylimide foam material according to claim 1, wherein: The co-solvent is selected from one or more of NMP, DMAC, DMF, DMSO, toluene and chloroform.

7. The high temperature resistant polyacrylimide foam material according to claim 1, wherein: The initiator is selected from one or more of tert-amyl peroxyacetate, benzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-amyl peroxybenzoate, tert-butyl peroxybenzoate, azobisisobutyronitrile and azoisobutylcyanoformamide.

8. The high temperature resistant polyacrylimide foam material according to claim 1, wherein: The foaming agent is selected from one or more of formamide, ethanol, propanol, isopropanol, tert-butanol and amyl alcohol.

9. The high temperature resistant polyacrylimide foam material according to claim 1, wherein: The cross-linking agent is selected from one or more of polyols, metal oxides, metal salt compounds, acrylamide, and methacrylamide.

10. A method for preparing a high temperature resistant polyacrylimide foam material according to any one of claims 1 to 9, wherein: The steps include: A carboxyl-containing acrylic monomer, a cyano-containing acrylonitrile monomer, a linear polyimide polymer, a cosolvent, an initiator, a foaming agent and a crosslinking agent are stirred and mixed in proportion at room temperature for 1-8 hours to form a homogeneous solution; The homogeneous solution is injected into a mold, and polymerized at 20-130° C. for 100-350 hours to obtain a polyimide foam prepolymer copolymer; The polyimide foam prepolymer copolymer obtained above is heated and foamed in the range of 180-250° C. to obtain the high temperature resistant polyacrylimide foam material.

11. Use of the high temperature resistant polyacrylimide foam material according to any one of claims 1 to 9 in the fields of aviation, aerospace, military industry, high temperature resistant materials, etc.

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