CN112745677B

CN112745677B - High-toughness polyimide sound-absorbing foam material and preparation method thereof

Info

Publication number: CN112745677B
Application number: CN202011609171.6A
Authority: CN
Inventors: 陶刚; 周明星; 庄洪伟; 田汝斌; 张金敏; 胡茂壮; 刘培礼
Original assignee: Qingdao Advanced Marine Material Technology Co ltd
Current assignee: Qingdao Advanced Marine Material Technology Co ltd
Priority date: 2020-12-30
Filing date: 2020-12-30
Publication date: 2022-06-21
Anticipated expiration: 2040-12-30
Also published as: CN112745677A

Abstract

The invention discloses a high-toughness polyimide sound absorption foam material and a preparation method thereof, wherein the high-toughness polyimide sound absorption foam material is prepared from aromatic dianhydride, low-molecular aliphatic alcohol, polar solvent, low-molecular aromatic diamine, unvulcanized high-temperature-resistant rubber and a surfactant; the preparation process comprises the following steps: preparing a diacid diester solution, carrying out acid-base neutralization reaction, preparing a precursor solution, preparing precursor powder, preparing a foam intermediate, curing after foam and the like. The material has excellent flexibility and sound absorption performance, and can be widely applied to application fields with higher requirements on flexibility and sound absorption performance, such as ship heat insulation, pipeline heat insulation and the like.

Description

High-toughness polyimide sound-absorbing foam material and preparation method thereof

Technical Field

The invention relates to the field of polyimide materials, in particular to a high-toughness polyimide sound-absorbing foam material and a preparation method thereof.

Background

The polyimide foam material is a porous material with a molecular main chain taking an imide ring as a main body and different open-cell structures, closed-cell structures or open-cell/closed-cell combined structures in the material. Because the polyimide molecular chain contains a large amount of nitrogen-containing five-membered heterocyclic rings and aromatic rings, and the aromatic heterocyclic rings form a conjugation effect, the polyimide material has excellent performances of high and low temperature resistance, radiation resistance, flame retardance, low fuming property and the like.

However, similarly, since the main chain of the polyimide molecule contains a large number of five-membered heterocyclic rings and aromatic ring structures, the polyimide foam material has strong overall rigidity and low elongation rate, which limits the application thereof to a certain extent. For example: in the field of ships, polyimide foam is often used as a heat insulating material for ship housings and a heat insulating material for pipelines because of its excellent flame retardancy, low smoke emission, low toxicity, and the like. In practical application, the problem that ship shells, pipelines and the like have radian structures is inevitable, in such a case, cutting sleeve blocks or slightly bending foam are adopted in engineering so as to enable the polyimide foam material to conform to the surface state of a base material, and the foam is adhered to the surface of the base material. After a period of application, the thermal insulation performance is reduced due to delamination between the foam and the substrate or peeling of the foam due to different thermal expansion coefficients of the substrate and the foam. In the field of aerospace, polyimide foam materials are used as filling materials to reduce vibration of parts and components in the process of aviation emission and advancing, and the effect of buffering and protecting is achieved. When the vibration is large, the destruction of the foam structure is often caused by insufficient flexibility of the polyimide foam. From the aspect of material performance, the damage is caused by insufficient toughness of polyimide foam, and the increase of the elongation at break of the material is one of important ways for improving the toughness of the material.

On the other hand, there is also a demand for sound absorption performance of materials at heat-insulating parts such as seawater pipelines and ship housings. The sound absorption performance of the polyimide foam material is still far from that of the common sound absorption foam such as polyurethane foam and melamine foam.

Therefore, the preparation of the foam material with excellent flexibility and sound absorption performance has important practical significance.

Patent CN 104945553 a proposes a method for preparing a high-toughness foam material. The method utilizes core-shell rubber to toughen the polyacrylamide foam material, and improves the elongation at break of PMI foam. The PMI foam material is a polyimide foam material formed by polymerizing acrylic monomers and acrylonitrile monomers, the main chain of the material is actually a nitrogen-containing six-membered heterocyclic ring structure, the polyimide foam material has the advantage of thermosetting property, but the material has poor combustion performance under the condition of not adding a flame retardant.

Patent CN 102618034 a proposes a preparation method of polyether amine modified isocyanate group polyimide foam. The method comprises the steps of reacting polyether amine modified foam combined liquid with polyisocyanate to prepare a foam intermediate, and then performing imidization reaction on the foam intermediate at high temperature by adopting a microwave or electric heating process to obtain the polyimide foam material. The method takes water, methanol and the like as foaming agents, and the inevitable side reaction in the foaming process is that the foaming agents react with isocyanate to obtain polyurethane groups. The generation of the polyurethane group increases the smoke generation amount of the polyimide foam, and decreases the heat resistance, flame retardancy, and the like of the polyimide foam.

Patent CN 201310172349.9; both cn201410333015.x and cn201510880307.x adopt a method of preparing a polyimide thermal insulation and sound absorption foam composite by adding an inorganic functional filler. As described in patent CN108948409A, the inorganic materials used in this method are liable to settle or separate in the foaming system, and have poor compatibility and uniformity, and it is difficult to prepare polyimide foam products having reliable and stable quality. In the patent CN108948409A, the inorganic functional filler is changed into an organic sound-absorbing material, such as polymer micropowder, organic silicon microspheres, organic porous material, etc., to solve the problem of poor compatibility of the inorganic sound-absorbing material. However, the organic sound absorption material is added into the system as a filler, and the mechanical properties of the whole material, especially the indexes such as elongation at break and the like related to the flexibility of the foam, are necessarily affected. And the B tank containing the solvent component is vacuumized in the implementation process of the patent, and the feasibility is poor because the solvent is pumped out of the system along with the vacuumizing process.

Disclosure of Invention

In order to solve the defects of the prior art, prepare the polyimide foam material with excellent flexibility and sound absorption performance and meet the requirements of application conditions such as ship heat preservation and sound absorption, pipeline heat preservation and the like, the invention provides the polyimide sound absorption foam material with high toughness and the preparation method thereof.

Rubber-like materials generally have very high molecular weights. The damping material has good damping performance, flexibility and the like due to the movement and friction of molecular chains and the physical entanglement among the macromolecular chains, and is widely applied to the fields of vibration damping, sound absorption and the like. The high-temperature-resistant elastomer material is added into the polyimide foam, and the sound absorption performance of the polyimide foam is hopefully improved by utilizing the molecular chain frictional heating effect of the elastomer material under the action of sound waves. On the other hand, the flexibility of the polyimide foam can be simultaneously improved in view of its inherent high elasticity, flexibility, and the like.

The invention provides a high-toughness polyimide sound-absorbing foam material which comprises the following raw materials in percentage by mass: 20-30% of aromatic dianhydride; 5-15% of low molecular weight fatty alcohol; 40-60% of polar solvent; 10-30% of aromatic diamine; 4-10% of unvulcanized high-temperature resistant rubber; 1-3% of surfactant.

The aromatic dianhydride used in the method is one or more of 3,3 ', 4, 4' -diphenyl ether tetracarboxyl dianhydride (ODPA), 3,3 ', 4, 4' -biphenyl tetracarboxyl dianhydride (BPDA), 3,3 ', 4, 4' -Benzophenone Tetracarboxyl Dianhydride (BTDA), pyromellitic dianhydride (PMDA) and 3,3 ', 4, 4' -biphenyl sulfone tetracarboxyl dianhydride (DSDA).

The low molecular weight aliphatic alcohol is one or more of methanol, ethanol, propanol and isopropanol.

The adopted polar solvent is one or more of N, N-Dimethylformamide (DMF), N-Diethylformamide (DEF), N-methylpyrrolidone (NMP), Tetrahydrofuran (THF) and dioxane.

The aliphatic diamine is one or more of 4,4 ' -diaminodiphenyl ether (4, 4 ' -ODA), p-phenylenediamine (p-PDA), 4 ' -diaminodiphenyl sulfone (4, 4 ' -DDS), 4 ' -diaminodiphenyl Methane (MDA) and the like.

The unvulcanized high-temperature resistant rubber is one or more of fluorosilicone rubber, silicone rubber, fluororubber, nitrile rubber, acrylate rubber, halogenated butyl rubber and the like.

The surfactant is water soluble silicone oil, including one of DC193, DC195, DC197, DC198 and DC5000 of Dow Corning company, and FS-B, FS-C of DuPont company.

The invention also provides the high-toughness polyimide sound absorption foam material, and the preparation process comprises the following steps:

(1) aromatic dianhydride and low molecular weight aliphatic alcohol are used for esterification reaction to prepare diacid diester solution.

Adding aromatic dianhydride into a polar solvent in which low-molecular-weight aliphatic alcohol is dissolved, wherein the molar ratio of the aromatic dianhydride to the low-molecular-weight aliphatic alcohol is 1: 2-1: 5. After fully stirring, heating to 70-80 ℃ for reflux esterification reaction. And after the solution becomes clear and transparent, continuing to react for 0.5h to obtain a diacid diester solution.

(2) The diacid diester and the diamine are utilized to carry out neutralization reaction.

Cooling the diacid diester solution synthesized in the step (1) to 40-50 ℃, and then adding low-molecular aromatic diamine into the diacid diester solution synthesized in the step (1), wherein the molar ratio of the aromatic diamine to the diacid diester is 1: 1. Fully stirring, heating to 60-65 ℃, and reacting for 0.5 h.

(3) Preparation of precursor solution

Adding unvulcanized high-temperature resistant rubber into the solution synthesized in the step (2), keeping the temperature at 60-65 ℃ and stirring until the rubber is completely dissolved to form a uniform and transparent solution. And finally, continuously adding a surfactant to obtain a precursor solution.

(4) Preparation of precursor powder from precursor solution

And (4) drying the precursor solution prepared in the step (3) by using spray drying equipment to obtain precursor powder.

(5) Foaming by using the precursor powder to prepare a foam intermediate.

And grinding and sieving the precursor powder until the particle size reaches below 300um, and then placing the powder in a toughened glass mold coated with tetrafluoroethylene, wherein the powder accumulation thickness is more than 1 cm. And placing the mould in special microwave equipment, setting the mass ratio of microwave power to precursor powder to be 1KW/kg, and heating by microwave for about 1h to obtain a foam intermediate.

(6) Post-curing of the foam intermediate.

And (3) placing the foam intermediate in an oven at 160-240 ℃, and heating and curing for 1-2h to obtain the high-toughness polyimide sound-absorbing foam material.

The invention has the following beneficial effects:

(1) a high-temperature resistant rubber system is added into the precursor solution, and the addition of the raw rubber can effectively improve the flexibility and the elongation of the polyimide foam material according to the macromolecular physical blending principle.

(2) A high-temperature-resistant rubber system is added into the precursor solution, and the sound absorption performance of the polyimide foam material is improved by utilizing the effect that the vibration energy is effectively converted into heat energy by the damping material in the process that sound waves penetrate through the foam wall because the rubber is an excellent damping material.

(3) The added rubber system can be dissolved in a precursor solution, and effective entanglement of polyimide molecular chains and rubber molecular chains is ensured by using the solution blending effect. The problems of precipitation, uneven mixing and the like caused by directly adding organic or inorganic sound absorption materials are avoided.

The high-toughness polyimide sound absorption foam material prepared by the invention has high elongation at break and average sound absorption coefficient, and can be widely applied to heat preservation of spherical surfaces, curved surfaces and other special-shaped surfaces with requirements on sound absorption performance, such as ship pipelines.

Drawings

FIG. 1 is a graph showing the results of the sound absorption coefficient test by the standing wave tube method in example 1.

FIG. 2 is a graph showing the results of the standing wave tube method sound absorption coefficient test of comparative example 1.

FIG. 3 is a graph showing the results of the sound absorption coefficient test by the standing wave tube method in example 2.

FIG. 4 is a graph showing the results of the standing wave tube method sound absorption coefficient test of FIG. 2.

FIG. 5 is a graph showing the results of sound absorption coefficient test by the reverberation chamber method in example 1.

FIG. 6 is a graph showing the results of the sound absorption coefficient test by the reverberant room method of comparative example 1.

Fig. 7 reverberation chamber sound absorption test site diagram.

FIG. 8 comparison of flexibility (left panel: polyimide foam prepared in this patent; right panel: conventional polyimide foam).

Detailed description of the invention

Example 1

(1) 500g of THF solvent, 322.2g of BTDA and 128g of methanol were placed in succession in a 2L three-necked flask equipped with a mechanical stirrer, a thermometer and a bulb condenser. After fully stirring, heating to 80 ℃ for reflux esterification reaction. And after the solution becomes clear and transparent, continuing to react for 0.5h to obtain a diacid diester solution of BTDA.

(2) And (2) cooling the diacid diester solution synthesized in the step (1) to 50 ℃, and then adding low-molecular aromatic diamine MDA into the diacid diester solution synthesized in the step (1), wherein the mass of the MDA is 198 g. After fully stirring, the temperature is raised to 65 ℃ and the reaction is carried out for 0.5 h.

(3) 58.42g of unvulcanized acrylate rubber was added to the solution synthesized in step (2), and the temperature was maintained at 65 ℃ and stirred until the rubber was completely dissolved to form a uniform transparent solution. And finally, continuously adding 30g of surfactant FS-B to obtain a precursor solution.

(4) And (4) drying the precursor solution prepared in the step (3) by using spray drying equipment to obtain precursor powder. The spray drying inlet temperature was set at 110 ℃ and the outlet temperature at 80 ℃.

(5) And grinding and sieving the precursor powder until the particle size reaches below 300um, and then placing the powder in a toughened glass mold coated with tetrafluoroethylene, wherein the powder accumulation thickness is more than 1 cm. And placing the mould in microwave equipment, setting the mass ratio of the microwave power to the precursor powder to be 1KW/kg, and heating for 1h by microwave to obtain a foam intermediate.

(6) And (3) placing the foam intermediate in an oven at 180 ℃, and heating and curing for 1h to obtain the high-toughness polyimide sound-absorbing foam material.

Example 2

(1) A2L three-necked flask equipped with a mechanical stirrer, a thermometer and a bulb condenser was charged with 500g of dioxane solvent, 218g of PMDA and 128g of methanol in this order. After fully stirring, heating to 80 ℃ for reflux esterification reaction. And after the solution becomes clear and transparent, continuing to react for 0.5h to obtain a diacid diester solution of PMDA.

(3) 58.42g of unvulcanized bromobutyl rubber was added to the solution synthesized in step (2), the temperature was maintained at 65 ℃ and stirring was carried out until the rubber was completely dissolved, forming a homogeneous transparent solution. And finally, continuously adding 30g of surfactant FS-B to obtain a precursor solution.

(4) And (4) drying the precursor solution prepared in the step (3) by utilizing spray drying equipment to obtain precursor powder. The spray drying inlet temperature was set at 150 ℃ and the outlet temperature at 80 ℃.

(5) And grinding and sieving the precursor powder until the particle size reaches below 300um, and then placing the powder in a toughened glass mold coated with tetrafluoroethylene, wherein the powder accumulation thickness is more than 1 cm. And (3) placing the mould in microwave equipment, setting the mass ratio of the microwave power to the precursor powder to be 1KW/kg, and heating for 1h by microwave to obtain a foam intermediate.

The present invention also provides the following 2 comparative examples with respect to example 1 and example 2, which are different from the examples in that unvulcanized high temperature resistant rubber was added to the examples, the comparative examples were not added, and other components and preparation were identical.

Comparative example 1

(3) And adding 30g of surfactant FS-B to obtain a precursor solution.

(4) And (4) drying the precursor solution prepared in the step (3) by utilizing spray drying equipment to obtain precursor powder. The spray drying inlet temperature was set at 110 ℃ and the outlet temperature at 80 ℃.

(5) And grinding and sieving the precursor powder until the particle size reaches below 300um, and then placing the powder in a toughened glass mold coated with tetrafluoroethylene, wherein the powder accumulation thickness is more than 1 cm. And placing the mould in special microwave equipment, setting the mass ratio of microwave power to precursor powder to be 1KW/kg, and heating for 1h by microwave to obtain a foam intermediate.

Comparative example 2

(3) And adding 30g of surfactant FS-B to obtain a precursor solution.

(4) And (4) drying the precursor solution prepared in the step (3) by using spray drying equipment to obtain precursor powder. The inlet temperature of the spray drying was set at-150 ℃ and the outlet temperature at 80 ℃.

Table 1 shows some of the physical-mechanical properties of the examples and comparative examples:

table 2 lists the results of the standing wave tube method sound absorption coefficient test for each example:

table 3 shows the sound absorption coefficient test data of the reverberation room method in example 1

Table 4 shows the sound absorption coefficient test data of the reverberation room method of comparative example 1

The data analysis shows that the elongation at break, the flexibility and the sound absorption coefficient of the polyimide foam can be effectively improved by adding the rubber material into the precursor solution, and the polyimide foam material with high toughness and sound absorption performance is prepared.

Claims

1. A high-toughness polyimide sound absorption foam material is prepared from the following raw materials in percentage by mass:

20-30% of aromatic dianhydride;

5-15% of low molecular weight fatty alcohol;

40-60% of polar solvent;

10-30% of aromatic diamine;

4-10% of unvulcanized high-temperature resistant rubber;

1-3% of a surfactant;

the unvulcanized high-temperature-resistant rubber is one or more of fluorosilicone rubber, silicone rubber, fluororubber, nitrile rubber, acrylate rubber and halogenated butyl rubber.

2. The high tenacity polyimide acoustic foam of claim 1 wherein: the aromatic dianhydride is one or more of 3,3 ', 4, 4' -diphenyl ether tetracarboxylic dianhydride (ODPA), 3 ', 4, 4' -biphenyl tetracarboxylic dianhydride (BPDA), 3 ', 4, 4' -Benzophenone Tetracarboxylic Dianhydride (BTDA), pyromellitic dianhydride (PMDA) and 3,3 ', 4, 4' -biphenyl sulfone tetracarboxylic dianhydride (DSDA).

3. The high toughness polyimide acoustic foam of claim 1 wherein: the low molecular weight aliphatic alcohol is one or more of methanol, ethanol, propanol and isopropanol.

4. The high tenacity polyimide acoustic foam of claim 1 wherein: the polar solvent is one or more of N, N-Dimethylformamide (DMF), N-Diethylformamide (DEF), N-methylpyrrolidone (NMP), Tetrahydrofuran (THF) and dioxane.

5. The high tenacity polyimide acoustic foam of claim 1 wherein: the low molecular aromatic diamine is one or more of 4,4 ' -diaminodiphenyl ether (4, 4 ' -ODA), p-phenylenediamine (p-PDA), 4 ' -diaminodiphenyl sulfone (4, 4 ' -DDS) and 4,4 ' -diaminodiphenyl Methane (MDA).

6. The high tenacity polyimide acoustic foam of claim 1 wherein: the surfactant is water-soluble silicone oil.

7. The high toughness polyimide acoustic foam of claim 6 wherein: the water-soluble silicone oil is selected from one of DC193, DC195, DC197, DC198 and DC5000 of Dow Corning company and FS-B, FS-C of DuPont company.

8. A process for preparing a high toughness polyimide acoustic foam according to any of the preceding claims, the process comprising essentially the steps of:

(1) preparing diacid diester solution by esterification reaction of aromatic dianhydride and low molecular aliphatic alcohol

Adding aromatic dianhydride into a polar solvent in which low-molecular aliphatic alcohol is dissolved, wherein the molar ratio of the aromatic dianhydride to the low-molecular aliphatic alcohol is 1: 2-1: 5; fully stirring, heating to 70-80 ℃ and carrying out reflux esterification reaction; continuing to react for 0.5h after the solution becomes clear and transparent to obtain a diacid diester solution;

(2) neutralization reaction by diacid diester and diamine

Cooling the diacid diester solution synthesized in the step (1) to 40-50 ℃, and then adding low-molecular aromatic diamine into the diacid diester solution synthesized in the step (1), wherein the molar ratio of aromatic diamine to diacid diester is 1: 1; fully stirring, heating to 60-65 ℃, and reacting for 0.5 h;

(3) preparation of precursor solution

Adding unvulcanized high-temperature-resistant rubber into the solution synthesized in the step (2), keeping the temperature at 60-65 ℃ and stirring until the rubber is completely dissolved to form a uniform and transparent solution; finally, continuously adding a surfactant to obtain a precursor solution;

(4) preparation of precursor powder from precursor solution

Drying the precursor solution prepared in the step (3) by using spray drying equipment to obtain precursor powder;

(5) foaming with precursor powder to prepare foam intermediate

Grinding and sieving the precursor powder until the particle size reaches below 300um, and then placing the powder in a toughened glass mold coated with tetrafluoroethylene, wherein the powder accumulation thickness is more than 1 cm; placing the mould in microwave equipment, setting the mass ratio of microwave power to precursor powder to be 1KW/kg, and heating for 1h by microwave to obtain a foam intermediate;

(6) post-curing of foam intermediates