Organosilicon-doped polyimide flexible foam material, and preparation method and application thereof
阅读说明：本技术 一种有机硅掺杂聚酰亚胺软质泡沫材料及制备方法、应用 (Organosilicon-doped polyimide flexible foam material, and preparation method and application thereof ) 是由 周光远 聂赫然 黄志成 顾铭茜 于 2021-08-06 设计创作，主要内容包括：本发明提供了一种聚酰亚胺软质泡沫材料,所述聚酰亚胺链结构中含有Si-C键和/或Si-O键；所述聚酰亚胺包括芳香族聚酰亚胺。该具有特定结构的有机硅掺杂聚酰亚胺软质泡沫材料,利用具有特殊结构的含硅芳香族二酐和芳香族二胺两类主原材料制备,由于所使用单体中存在C-Si键和/或Si-O键,使得本发明提供聚酰亚胺软质泡沫材料具有非常优异的耐高低温性能和高效的阻燃防火性能,同时保持极好的柔韧性,并且在抗紫外线方面表现突出。此外,本发明提供的有机硅掺杂聚酰亚胺软质泡沫材料具有表观密度较小的特点,而且工艺简单、易于控制,有利于实现工业连续化生产,非常适合应用于航空航天飞行器领域。(The invention provides a polyimide flexible foam material, wherein a polyimide chain structure contains Si-C bonds and/or Si-O bonds; the polyimide includes an aromatic polyimide. The organic silicon-doped polyimide flexible foam material with the specific structure is prepared by using two main raw materials of silicon-containing aromatic dianhydride and aromatic diamine with special structures, and because C-Si bonds and/or Si-O bonds exist in the used monomers, the polyimide flexible foam material provided by the invention has excellent high and low temperature resistance and efficient flame-retardant and fireproof performances, and simultaneously keeps excellent flexibility and is outstanding in ultraviolet resistance. In addition, the organosilicon-doped polyimide flexible foam material provided by the invention has the characteristic of small apparent density, is simple in process and easy to control, is beneficial to realizing industrial continuous production, and is very suitable for being applied to the field of aerospace aircrafts.)
1. A polyimide flexible foam material characterized in that the polyimide chain structure contains Si-C bonds and/or Si-O bonds;
the polyimide includes an aromatic polyimide.
2. The polyimide flexible foam according to claim 1, wherein the Si-C bonds are linked in a polyimide chain structure by Si bonds;
the Si-O bond is connected in the polyimide chain structure through O or Si;
the Si-C bond and/or the Si-O bond are/is connected into a polyimide chain structure through aromatic dianhydride;
the density of the polyimide flexible foam material is less than or equal to 10kg/m3；
The polyimide flexible foam material has a compression set of 10% or less.
3. The polyimide flexible foam according to claim 2, wherein the aromatic dianhydride is a silicon-containing aromatic dianhydride;
the silicon-containing aromatic dianhydride is characterized in that a group containing the Si-C bond and/or a group containing the Si-O bond is bridged between benzene rings of two phthalic anhydrides;
when the group containing the Si-C bond and/or the group containing the Si-O bond contains a rigid group, the molar ratio of the Si to the rigid group is more than or equal to 2;
the polyimide soft foam material is an organosilicon-doped polyimide soft foam material;
the polyimide soft foam material is used for aerospace aircrafts.
4. The polyimide flexible foam according to claim 2, wherein the group having the Si-C bond and/or the group having the Si-O bond is bridged between a benzene ring and a benzene ring of an aromatic dianhydride;
the aromatic dianhydride has a structure shown as a structural formula (1):
wherein R is selected from one or more of structural formulas (2) to (6);
5. the polyimide soft foam material is characterized by comprising the following raw materials in parts by mass:
6. the polyimide flexible foam according to claim 5, wherein the aromatic diamine has a structure represented by the formula (7);
wherein X is selected from one or more of structural formulas (8) to (12);
the polyimide flexible foam material has an open-cell structure;
the opening rate of the polyimide soft foam material is 95-100%;
the aperture of the polyimide flexible foam material is 150-300 mu m.
7. The polyimide flexible foam according to claim 5, wherein the solvent comprises one or more of DMF, DMAC, NMP and DMSO;
the small molecular weight alcohol comprises CH3OH、C2H5OH and C3H7One or more of OH;
the other auxiliary agents comprise one or more of a foam stabilizer, a catalyst and a foaming agent;
the foam stabilizer comprises one or more of OFX-0193, OFX-8417, OFX-8468, L550, L540, L580, L668 and L5333;
the catalyst comprises one or more of triethylene diamine, N-methylmorpholine, N '-diethylpiperazine, N' -diethyl-2-methylpiperazine and N-2-hydroxypropyl dimethylmorpholine;
the foaming agent comprises one or more of barium azodicarboxylate, azodicarbonamide, boric acid, sodium alpha-olefin sulfonate and sodium bicarbonate.
8. A method for producing the polyimide flexible foam according to any one of claims 1 to 4 or the polyimide flexible foam according to any one of claims 5 to 7, comprising the steps of:
1) carrying out esterification reaction on aromatic dianhydride, a solvent and low molecular weight alcohol to obtain an intermediate;
2) and (3) reacting the intermediate obtained in the step, aromatic diamine and other auxiliaries to obtain a foaming precursor, and performing foaming molding to obtain the polyimide flexible foam material.
9. The preparation method according to claim 8, wherein the temperature of the esterification reaction is 50 to 80 ℃;
the esterification reaction time is 1-5 h;
the reaction temperature is 100-150 ℃;
the reaction time is 2-5 h;
the foaming molding temperature is 200-250 ℃;
the foaming and forming time is 1-30 min.
10. Use of the flexible polyimide foam according to any one of claims 1 to 4, the flexible polyimide foam according to any one of claims 5 to 7, or the flexible polyimide foam produced by the production method according to any one of claims 8 to 9 in the field of aerospace.
Technical Field
The invention belongs to the technical field of polyimide flexible foam materials, relates to a polyimide flexible foam material, and a preparation method and application thereof, and particularly relates to an organic silicon doped polyimide flexible foam material, a preparation method thereof, and application thereof in the aerospace field.
Background
Polyimide is a polymer with excellent heat resistance, has good mechanical property and electrical property, radiation resistance and corrosion resistance, and is widely applied to the fields of aerospace, military, electronics and the like. The polyimide material with the foam structure not only keeps excellent temperature resistance, flame retardance and other performances of the original resin, but also has outstanding heat preservation characteristic and comprehensive performances of light weight, good flexible resilience, environmental protection, no toxicity, flame retardance, convenient use and the like.
The polyimide foam material is used as the most elegant heat-insulating sound-insulating material and is applied to the basic configuration in the aerospace field of various countries and military ships of developed countries in the west. In the field of aerospace, in the long-term service of conventional polyimide foam materials, in the face of extreme conditions such as ultrahigh temperature, ultralow temperature, strong radiation and the like, more severe requirements are put forward on the aspects of temperature resistance, radiation resistance and the like of the materials so as to meet the corresponding industry requirements. Meanwhile, huge heat is generated due to air friction in the launching process of the aerospace craft, and the requirements for further improving the heat insulation performance and the flame retardant performance of the polyimide foam material are met in order to protect the safety of relevant equipment inside the aerospace craft.
Therefore, how to further improve the heat insulation performance and the flame retardant performance of the polyimide foam material, and better satisfy the application requirements of the downstream industry, especially the higher requirements in the aerospace field, has become one of the focuses of many research and development manufacturers and the first line of research personnel.
Disclosure of Invention
In view of the above, the technical problem to be solved by the present invention is to provide a polyimide flexible foam material, a preparation method and an application thereof, and in particular, to an organosilicon-doped polyimide flexible foam material, a preparation method thereof and an application thereof in the aerospace field. The polyimide flexible foam material provided by the invention is introduced with silicon element and/or oxygen element through a bridging structure design, so that the polyimide flexible foam material has excellent high and low temperature resistance and efficient flame-retardant and fireproof performance, keeps excellent flexibility and is outstanding in ultraviolet resistance. And the process is simple and easy to control, and is favorable for realizing industrial continuous production.
The invention provides a polyimide flexible foam material, wherein a polyimide chain structure contains Si-C bonds and/or Si-O bonds;
the polyimide includes an aromatic polyimide.
Preferably, the Si — C bond is linked in the polyimide chain structure through Si;
the Si-O bond is connected in the polyimide chain structure through O or Si;
the Si-C bond and/or the Si-O bond are/is connected into a polyimide chain structure through aromatic dianhydride;
the density of the polyimide flexible foam material is less than or equal to 10kg/m3；
The polyimide flexible foam material has a compression set of 10% or less.
Preferably, the aromatic dianhydride is silicon-containing aromatic dianhydride;
the silicon-containing aromatic dianhydride is characterized in that a group containing the Si-C bond and/or a group containing the Si-O bond is bridged between benzene rings of two phthalic anhydrides;
when the group containing the Si-C bond and/or the group containing the Si-O bond contains a rigid group, the molar ratio of the Si to the rigid group is more than or equal to 2;
the polyimide soft foam material is an organosilicon-doped polyimide soft foam material;
the polyimide soft foam material is used for aerospace aircrafts.
Preferably, the group containing the Si-C bond and/or the group containing the Si-O bond is bridged between a benzene ring and a benzene ring of the aromatic dianhydride;
the aromatic dianhydride has a structure shown as a structural formula (1):
wherein R is selected from one or more of structural formulas (2) to (6);
the invention provides a polyimide soft foam material which comprises the following raw materials in parts by weight:
preferably, the aromatic diamine has a structure represented by formula (7);
wherein X is selected from one or more of structural formulas (8) to (12);
the polyimide flexible foam material has an open-cell structure;
the opening rate of the polyimide soft foam material is 95-100%;
the aperture of the polyimide flexible foam material is 150-300 mu m.
Preferably, the solvent comprises one or more of DMF, DMAC, NMP and DMSO;
the small molecular weight alcohol comprises CH3OH、C2H5OH and C3H7One or more of OH;
the other auxiliary agents comprise one or more of a foam stabilizer, a catalyst and a foaming agent;
the foam stabilizer comprises one or more of OFX-0193, OFX-8417, OFX-8468, L550, L540, L580, L668 and L5333;
the catalyst comprises one or more of triethylene diamine, N-methylmorpholine, N '-diethylpiperazine, N' -diethyl-2-methylpiperazine and N-2-hydroxypropyl dimethylmorpholine;
the foaming agent comprises one or more of barium azodicarboxylate, azodicarbonamide, boric acid, sodium alpha-olefin sulfonate and sodium bicarbonate.
The present invention provides a polyimide flexible foam material according to any one of the above technical aspects or a method for producing a polyimide flexible foam material according to any one of the above technical aspects, comprising the steps of:
1) carrying out esterification reaction on aromatic dianhydride, a solvent and low molecular weight alcohol to obtain an intermediate;
2) and (3) reacting the intermediate obtained in the step, aromatic diamine and other auxiliaries to obtain a foaming precursor, and performing foaming molding to obtain the polyimide flexible foam material.
Preferably, the temperature of the esterification reaction is 50-80 ℃;
the esterification reaction time is 1-5 h;
the reaction temperature is 100-150 ℃;
the reaction time is 2-5 h;
the foaming molding temperature is 200-250 ℃;
the foaming and forming time is 1-30 min.
The invention also provides the polyimide flexible foam material prepared by the preparation method of any one of the above technical schemes, and the application of the polyimide flexible foam material prepared by any one of the above technical schemes or the polyimide flexible foam material prepared by the preparation method of any one of the above technical schemes in the aerospace field.
The invention provides a polyimide flexible foam material, wherein a polyimide chain structure contains Si-C bonds and/or Si-O bonds; the polyimide includes an aromatic polyimide. Compared with the prior art, the invention aims at the problem that the heat-insulating property and the flame retardant property of the existing soft polyimide foam material need to be further improved. The invention particularly adopts an organic silicon compound as an improved research direction, the organic silicon compound is in a main chain structure with a silicon-oxygen bond, the bond energy of a carbon-carbon bond is 82.6 kilocalories per gram molecule, and the bond energy of the silicon-oxygen bond is 121 kilocalories per gram molecule in organic silicon, so the organic silicon compound has high thermal stability, and the chemical bond of the molecule is not broken or decomposed at high temperature (or radiation irradiation). The organosilicon can resist high temperature and low temperature, and can be used in a wide temperature range. The change with temperature is small whether the chemical property or the physical and mechanical property is changed. And the organosilicon series compounds are not easy to be decomposed by ultraviolet light and ozone, and have better thermal stability, irradiation resistance and weather resistance than other high polymer materials. The backbone of silicone is very flexible, has the characteristics of low surface tension and low surface energy, and the intermolecular force is much weaker than that of hydrocarbon. The invention further utilizes a specific organic silicon doping mode to obtain the organic silicon doped polyimide foam material with a specific structure, thereby meeting the requirements of the organic silicon doped polyimide foam material in the field of aerospace.
According to the organosilicon-doped polyimide soft foam material with the specific structure, the bridging part of the aromatic dianhydride is designed, silicon element and/or oxygen element is introduced into the bridging structure, silicon-containing aromatic dianhydride monomers with different structures are prepared, so that the aromatic silicon dianhydride has outstanding temperature resistance, flame retardance, ultraviolet resistance and other performances, the silicon-containing aromatic dianhydride and specific aromatic diamine are combined and introduced into a specific position in a polyimide high polymer main chain, and the organosilicon-doped polyimide soft foam material prepared from the silicon-containing aromatic dianhydride monomers is obtained, so that the organosilicon-doped polyimide soft foam material with the specific structure has extremely excellent temperature resistance, flame retardance and fire resistance and molecular chain flexibility.
According to the invention, the polyimide flexible foam material is prepared by using the silicon-containing aromatic dianhydride and the aromatic diamine which have special structures and performances, and because the monomers used in the invention have C-Si bonds and/or Si-O bonds, the polyimide flexible foam material provided by the invention has very excellent high and low temperature resistance and efficient flame-retardant and fireproof performances, and simultaneously keeps excellent flexibility and is outstanding in ultraviolet resistance. In addition, the organosilicon-doped soft polyimide foam material provided by the invention has the characteristic of small apparent density, is simple in process and easy to control, is beneficial to realizing industrial continuous production, and is very suitable for being applied to the field of aerospace aircrafts.
Experimental results show that the organic silicon-doped polyimide flexible foam material provided by the invention has extremely excellent temperature resistance, flame-retardant and fireproof performance, molecular chain flexibility, smaller apparent density and density of only 7kg/m3The 5% thermal weight loss temperature is 573 ℃, the limiting oxygen index is up to 56%, the thermal conductivity is 0.032W/m.K, and the compression permanent deformation is less than 4%, so that the thermal insulation material is very suitable for being applied to the field of aerospace aircrafts.
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 analytical grade or polyimide flexible 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 polyimide flexible foam material, wherein a polyimide chain structure contains Si-C bonds and/or Si-O bonds;
the polyimide includes an aromatic polyimide.
In the present invention, the Si — C bond is preferably bonded in the polyimide chain structure through Si.
In the present invention, the Si — O bond is preferably bonded in the polyimide chain structure through O or Si.
In the present invention, the Si-C bond and/or the Si-O bond is preferably incorporated into the polyimide chain structure through an aromatic dianhydride.
In the present invention, the density of the polyimide flexible foam is preferably 10kg/m or less3More preferably 9kg/m or less3More preferably not more than 8kg/m3Specifically, it may be 7 to 10kg/m3Or 7 to 9kg/m3Or 7 to 8kg/m3。
In the present invention, the polyimide flexible foam preferably has a permanent compression set of 10% or less, more preferably 8% or less, and still more preferably 4% or less. Specifically, the concentration of the surfactant can be 4-10%, or 4.3-8%, or 4.5-6%.
In the present invention, the silicon-containing aromatic dianhydride is particularly preferably a group containing the Si-C bond and/or a group containing the Si-O bond bridged between the benzene rings of two phthalic anhydrides.
In the present invention, the group containing the Si-C bond and/or the group containing the Si-O bond is preferably bridged between the benzene ring and the benzene ring of the aromatic dianhydride.
In the present invention, the aromatic dianhydride is preferably a silicon-containing aromatic dianhydride. Specifically, the aromatic dianhydride preferably has a structure represented by the structural formula (1):
among them, R is preferably selected from one or more of structural formulae (2) to (6), and more preferably (2), (3), (4), (5) or (6).
In particular, in the present invention, in the group having an Si — C bond and/or the group having an Si — O bond, when a rigid group is contained, the molar ratio of Si to the rigid group is 2 or more. Namely, the molar ratio is more than or equal to 2: 1, may be 2.5 or more: 1, may be not less than 3: 1. specifically, the rigid group preferably includes a five-membered ring or more, and more preferably includes a six-membered ring or more. May be a five-membered heterocyclic ring, a benzene ring, a naphthalene ring, a condensed ring, or the like,
In the present invention, the polyimide flexible foam is preferably a silicone-doped polyimide flexible foam.
In the present invention, the polyimide flexible foam preferably has an open-cell structure.
In the present invention, the open cell content of the polyimide flexible foam is preferably 95% to 100%, more preferably 96% to 99%, and still more preferably 97% to 98%.
In the present invention, the pore diameter of the polyimide flexible foam is preferably 150 to 300. mu.m, more preferably 180 to 270. mu.m, and still more preferably 210 to 240. mu.m.
In the present invention, the polyimide flexible foam is preferably a polyimide flexible foam for aerospace vehicles.
The invention also provides a polyimide soft foam material which comprises the following raw materials in parts by weight:
in the present invention, the aromatic dianhydride is preferably added in an amount of 15 to 40 parts by weight, more preferably 20 to 35 parts by weight, and even more preferably 25 to 30 parts by weight.
In the present invention, the aromatic dianhydride is preferably a silicon-containing aromatic dianhydride. Specifically, the aromatic dianhydride preferably has a structure represented by the structural formula (1):
among them, R is preferably selected from one or more of structural formulae (2) to (6), and more preferably (2), (3), (4), (5) or (6). Specifically, the preparation method of the silicon-containing aromatic dianhydride is preferably prepared according to the conventional method or prepared by performing conventional modification according to the conventional preparation method of silicon-containing aromatic dianhydride with a similar structure.
In the present invention, the aromatic diamine 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.
In the present invention, the aromatic diamine preferably has a structure represented by the structural formula (7);
among them, X is preferably selected from one or more of structural formulae (8) to (12), and more preferably (8), (9), (10), (11) or (12).
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. The solvent preferably comprises one or more of DMF, DMAC, NMP and DMSO, more preferably DMF, DMAC, NMP or DMSO.
In the present invention, the small molecular weight alcohol is preferably added in an amount of 1 to 5 parts by weight, more preferably 1.5 to 4.5 parts by weight, more preferably 2 to 4 parts by weight, and more preferably 2.5 to 3.5 parts by weight.
In the present invention, the small molecular weight alcohol preferably includes CH3OH、C2H5OH and C3H7One or more of OH, more preferably CH3OH、C2H5OH or C3H7OH。
In the present invention, the amount of the other additives added 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 other auxiliary agents preferably include one or more of a foam stabilizer, a catalyst and a foaming agent, and more preferably, the foam stabilizer, the catalyst and the foaming agent.
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 catalyst preferably comprises one or more of triethylenediamine, N-methylmorpholine, N '-diethylpiperazine, N' -diethyl-2-methylpiperazine and N-2-hydroxypropyl dimethylmorpholine, more preferably triethylenediamine, N-methylmorpholine, N '-diethylpiperazine, N' -diethyl-2-methylpiperazine or N-2-hydroxypropyl dimethylmorpholine.
In the present invention, the foaming agent preferably includes one or more of barium azodicarboxylate, azodicarbonamide, boric acid, sodium alpha-olefin sulfonate, and sodium bicarbonate, more preferably barium azodicarboxylate, azodicarbonamide, boric acid, sodium alpha-olefin sulfonate, or sodium bicarbonate.
In the present invention, the silicone-doped polyimide flexible foam preferably has the general formula shown in formula (13).
Wherein n is the degree of polymerization. Specifically, n is preferably 10 to 100, more preferably 30 to 80, and still more preferably 50 to 60.
In the present invention, the silicone-doped polyimide flexible foam is preferably a linear polyimide foam. I.e., a thermoplastic polyimide foam.
The polyimide flexible foam material provided by the invention has excellent high and low temperature resistance and efficient flame-retardant and fireproof performance, keeps excellent flexibility and has outstanding ultraviolet resistance by adopting the specific monomer with C-Si bonds and/or Si-O bonds.
The invention also provides a polyimide flexible foam material as described in any one of the above technical schemes or a preparation method of the polyimide flexible foam material as described in any one of the above technical schemes, which comprises the following steps:
1) carrying out esterification reaction on aromatic dianhydride, a solvent and low molecular weight alcohol to obtain an intermediate;
2) and (3) reacting the intermediate obtained in the step, aromatic diamine and other auxiliaries to obtain a foaming precursor, and performing foaming molding to obtain the polyimide flexible foam material.
Firstly, aromatic dianhydride, solvent and low molecular weight alcohol are subjected to esterification reaction to obtain an intermediate.
In the invention, the temperature of the esterification reaction is preferably 50-80 ℃, more preferably 55-75 ℃, and more preferably 60-70 ℃.
In the invention, the esterification reaction time is preferably 1-5 h, more preferably 1.5-4.5 h, more preferably 2-4 h, and more preferably 2.5-3.5 h.
The intermediate obtained in the step, the aromatic diamine and other auxiliary agents react to obtain a foaming precursor, and the foaming precursor is subjected to foaming molding to obtain the polyimide flexible foam material.
In the invention, the reaction temperature is preferably 100-150 ℃, more preferably 105-145 ℃, more preferably 110-140 ℃, more preferably 115-135 ℃, and more preferably 120-130 ℃.
In the invention, the reaction time is preferably 2-5 h, more preferably 2.5-4.5 h, and more preferably 3-4 h.
In the present invention, the reaction is preferably followed by one or more of concentration, desolvation and pulverization steps, and more preferably followed by multiple steps of concentration, desolvation and pulverization steps, to obtain a foamed precursor.
In the invention, the foaming temperature is preferably 200-250 ℃, more preferably 220-250 ℃, and more preferably 230-240 ℃.
In the invention, the foaming time is preferably 1-30 min, more preferably 5-25 min, and more preferably 10-20 min.
The invention is a complete and refined integral preparation process, which better ensures the performance and the structure of the polyimide soft foam material, and the preparation method of the polyimide soft foam material can specifically comprise the following steps:
1) dissolving aromatic silicon-containing dianhydride in a polar solvent, and adding low molecular weight alcohol to carry out esterification reaction to obtain a product I;
2) continuously adding aromatic diamine and other assistants into the product I to react to obtain a product II;
3) and sequentially concentrating, removing the solvent and pulverizing the product II to obtain a foaming precursor, and finally preparing the organic silicon doped polyimide soft foam material through a foaming forming process.
The invention also provides the polyimide flexible foam material in any one of the technical schemes, the polyimide flexible foam material in any one of the technical schemes or the polyimide flexible foam material prepared by the preparation method in any one of the technical schemes, and the application of the polyimide flexible foam material in the aerospace field.
The invention provides an organosilicon-doped polyimide flexible foam material, a preparation method thereof and application in the field of aerospace. According to the organosilicon-doped polyimide soft foam material with the specific structure, the bridging part of the aromatic dianhydride is designed, silicon element and/or oxygen element is introduced into the bridging structure, silicon-containing aromatic dianhydride monomers with different structures are prepared, so that the aromatic silicon dianhydride has outstanding temperature resistance, flame retardance, ultraviolet resistance and other performances, the silicon-containing aromatic dianhydride and specific aromatic diamine are combined and introduced into a specific position in a polyimide high polymer main chain, and the organosilicon-doped polyimide soft foam material prepared from the silicon-containing aromatic dianhydride monomers is obtained, so that the organosilicon-doped polyimide soft foam material with the specific structure has extremely excellent temperature resistance, flame retardance and fire resistance and molecular chain flexibility.
According to the invention, the polyimide flexible foam material is prepared by using the silicon-containing aromatic dianhydride and the aromatic diamine which have special structures and performances, and because the monomers used in the invention have C-Si bonds and/or Si-O bonds, the polyimide flexible foam material provided by the invention has very excellent high and low temperature resistance and efficient flame-retardant and fireproof performances, and simultaneously keeps excellent flexibility and is outstanding in ultraviolet resistance. In addition, the organosilicon-doped polyimide flexible foam material provided by the invention has the characteristic of small apparent density, is simple in process and easy to control, is beneficial to realizing industrial continuous production, and is very suitable for being applied to the field of aerospace aircrafts.
Experimental results show that the organic silicon-doped polyimide flexible foam material provided by the invention has extremely excellent temperature resistance, flame-retardant and fireproof performance, molecular chain flexibility, smaller apparent density and density of only 7kg/m3The 5% thermal weight loss temperature is 573 ℃, the limiting oxygen index is up to 56%, the thermal conductivity is 0.032W/m.K, and the compression permanent deformation is less than 4%, so that the thermal insulation material is very suitable for being applied to the field of aerospace aircrafts.
For further illustration of the present invention, the following will describe a polyimide flexible foam and its preparation method and application in detail with reference to the following examples, but it should be understood that these examples are carried out on the premise of the technical solution of the present invention, and the detailed embodiments and specific procedures are given, only for further illustration of the features and advantages of the present invention, not for limitation of the claims of the present invention, and the scope of protection of the present invention is not limited to the following examples.
Example 1
1) 24 parts of an aromatic silicon-containing dianhydride represented by the formula (3) in which R is a moiety represented by the following formula (3) is dissolved in 30 parts of DMF, and 6 parts of C is added2H5Performing esterification reaction on OH at 50 ℃ for 3h to obtain a product I;
2) continuously adding 25 parts of aromatic diamine with the X part of a structural formula (9), 8 parts of L580, 2 parts of N-2-hydroxypropyl dimethyl morpholine and 5 parts of alpha-olefin sodium sulfonate into the product I, and reacting at 120 ℃ for 3 hours to obtain a product II;
3) and sequentially concentrating, removing the solvent and pulverizing the product II to obtain a foaming precursor, and finally performing foaming molding at 220 ℃ for 30min to obtain the polyimide soft foam material.
Example 2
1) 24 parts of an aromatic silicon-containing dianhydride represented by the formula (4) in the R portion was dissolved in 30 parts of DMF, and 6 parts of C was added2H5Performing esterification reaction on OH at 50 ℃ for 3h to obtain a product I;
2) continuously adding 25 parts of aromatic diamine with the X part of a structural formula (9), 8 parts of L580, 2 parts of N-2-hydroxypropyl dimethyl morpholine and 5 parts of alpha-olefin sodium sulfonate into the product I, and reacting at 120 ℃ for 3 hours to obtain a product II;
3) and sequentially concentrating, removing the solvent and pulverizing the product II to obtain a foaming precursor, and finally performing foaming molding at 220 ℃ for 30min to obtain the polyimide soft foam material.
Example 3
1) 24 parts of an aromatic silicon-containing dianhydride represented by the formula (5) in the R portion was dissolved in 30 parts of DMF, and 6 parts of C was added2H5Performing esterification reaction on OH at 50 ℃ for 3h to obtain a product I;
2) continuously adding 25 parts of aromatic diamine with the X part of the structural formula (10), 8 parts of L580, 2 parts of N-2-hydroxypropyl dimethyl morpholine and 5 parts of alpha-olefin sodium sulfonate into the product I, and reacting at 120 ℃ for 3 hours to obtain a product II;
3) and sequentially concentrating, removing the solvent and pulverizing the product II to obtain a foaming precursor, and finally performing foaming molding at 230 ℃ for 30min to obtain the polyimide soft foam material.
Comparative example 1
1) 24 parts of phthalic anhydride are dissolved in 30 parts of DMF and 6 parts of C are added2H5Performing esterification reaction on OH at 50 ℃ for 3h to obtain a product I;
2) continuously adding 25 parts of aromatic diamine with the X part of a structural formula (9), 8 parts of L580, 2 parts of N-2-hydroxypropyl dimethyl morpholine and 5 parts of alpha-olefin sodium sulfonate into the product I, and reacting at 120 ℃ for 3 hours to obtain a product II;
3) and sequentially concentrating, removing the solvent and pulverizing the product II to obtain a foaming precursor, and finally performing foaming molding at 20 ℃ for 30min to obtain the polyimide soft foam material.
Comparative example 2
1) 24 portions of R are of the formulaThe aromatic silicon-containing dianhydride (C) was dissolved in 30 parts of DMF, and 6 parts of C was added2H5Performing esterification reaction on OH at 50 ℃ for 3h to obtain a product I;
2) continuously adding 25 parts of aromatic diamine with the X part of a structural formula (9), 8 parts of L580, 2 parts of N-2-hydroxypropyl dimethyl morpholine and 5 parts of alpha-olefin sodium sulfonate into the product I, and reacting at 120 ℃ for 3 hours to obtain a product II;
3) and sequentially concentrating, removing the solvent and pulverizing the product II to obtain a foaming precursor, and finally performing foaming molding at 220 ℃ for 30min to obtain the polyimide soft foam material.
The polyimide foams prepared in the examples of the present invention and comparative examples were subjected to a performance test.
The foam density test standard is GB/T6343-.
Referring to table 1, table 1 shows the results of performance tests of the polyimide flexible foams prepared in examples of the present invention and comparative examples.
TABLE 1
The results of the examples 1 to 3 and the comparative examples 1 and 2 show that the density of the silicon-containing polyimide flexible foam material prepared from the silicon-containing aromatic dianhydride monomer is obviously lower than that of the conventional polyimide foam, and the silicon-containing polyimide flexible foam material is superior to that of the conventional polyimide foam in flame retardant and fireproof performance, temperature resistance, heat insulation and heat preservation performance and the like. And more cyclic rigid structures in the bridge group can cause the aperture of the foam material to be enlarged, thereby influencing the heat insulation performance and the resilience performance of the foam material.
While the present invention has been described in detail with reference to specific examples thereof, the principles and embodiments of the present invention are explained herein using specific examples, which are provided 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.