CN114920974B - Recycling method of polyimide sponge - Google Patents
Recycling method of polyimide sponge Download PDFInfo
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- CN114920974B CN114920974B CN202210744293.9A CN202210744293A CN114920974B CN 114920974 B CN114920974 B CN 114920974B CN 202210744293 A CN202210744293 A CN 202210744293A CN 114920974 B CN114920974 B CN 114920974B
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/0061—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof characterized by the use of several polymeric components
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J11/00—Recovery or working-up of waste materials
- C08J11/04—Recovery or working-up of waste materials of polymers
- C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
- C08J11/14—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with steam or water
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/0014—Use of organic additives
- C08J9/0033—Use of organic additives containing sulfur
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2379/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2361/00 - C08J2377/00
- C08J2379/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
- C08J2379/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2477/00—Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
- C08J2477/10—Polyamides derived from aromatically bound amino and carboxyl groups of amino carboxylic acids or of polyamines and polycarboxylic acids
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/62—Plastics recycling; Rubber recycling
Abstract
The application discloses a recycling method of polyimide sponge, belongs to the technical field of polyimide porous materials, and solves the technical problems of low preparation efficiency, difficult recycling of components, unsustainable materials and the like of the existing polyimide foam and polyimide aerogel. According to the cyclic regeneration method of the polyimide sponge, disclosed by the application, the combination of hydraulic fluffing and mechanical defibration is adopted, so that the use of toxic and harmful polar solvents is avoided, the green cyclic recycling and sustainable preparation of fiber components in the polyimide porous material are realized, and the performance of the circularly prepared polyimide porous material is equivalent to that of raw materials; solves the problems of low preparation efficiency, difficult component recycling, uncontinuous material and the like of the existing polyimide foam and polyimide aerogel, and provides a new method and possibility for the cyclic preparation and green sustainable development of polyimide porous materials.
Description
Technical Field
The application belongs to the technical field of polyimide porous materials, and particularly relates to a cyclic regeneration method of polyimide sponge.
Background
The porous materials such as polyimide foam, aerogel and the like have high porosity and excellent heat insulation and sound absorption properties, and are important basic materials for realizing the development of carrying equipment in the fields of rail transit and aerospace navigation to large scale, light weight and greenness. However, the existing polyimide foam and aerogel porous materials have the problems of low preparation efficiency, difficult recycling, unsustainable and the like, and provide challenges for green preparation and sustainable development of the materials. The development of the green recyclable polyimide porous material preparation technology has important significance for sustainable development of propulsion materials, further widening the application field and promoting the development of energy conservation, noise reduction and low carbon reduction of large equipment.
The main forms of polyimide porous materials include the following two types: polyimide foams and polyimide aerogels.
1) Polyimide foam
Currently, polyimide foams are mainly prepared in one-step or two-step processes. Research shows that the one-step preparation process of polyimide foam is simple and the instrument and equipment are easy to operate. Polyimide foam is prepared by aromatic dianhydride and triphenylmethane triisocyanate adhesive through a one-step method, and CO generated in the process is adopted 2 As a foaming agent, the mechanical strength and the thermal stability of the foam are prevented from being influenced by byproducts, but the polyimide foam prepared by the one-step method has lower apparent density and heat insulation performance; when the polyimide sponge is prepared by adopting a two-step method, although the prepared foam has the characteristics of high density, high compressive strength and good heat insulation performance, the foam has a non-uniform cell structure and a complex preparation process.
2) Polyimide aerogel
In addition to the common solvent foaming process for preparing polyimide foam, polyimide aerogel is also an important polyimide porous heat insulation material. Wherein CO 2 The drying processes such as supercritical drying, normal pressure drying, freeze drying and the like are important factors influencing the structure and the performance of polyimide aerogel; supercritical drying has limited its application due to limitations in terms of preparation conditions and sample size. At present, freeze drying is also one of the most important means for preparing polyimide aerogel, and polyimide ammonium salt/clay mixed suspension is freeze dried and imidized under different temperature conditions to obtain the low-density polyimide/clay composite aerogel. The density of the obtained composite aerogel material is 0.04-0.09 g/cm 3 In between, with the increase of PI content, the composite material presents a more perfect 'layer-branch' supporting structure, and the compression modulus of the composite material is improved compared with that of the unmodified clay aerogel5-50 times.
Although polyimide aerogel prepared by the methods of supercritical drying, freeze drying and the like of polyimide foam prepared by the one-step method and the two-step method has the characteristics of light weight, heat insulation and sound absorption, the problems of low preparation efficiency, difficult component recycling, unsustainable materials and the like of the above methods inevitably exist. How to avoid using toxic and harmful polar solvents, and the method for recycling the polyimide porous material components in a green and efficient way and circularly preparing the polyimide porous material becomes a problem of sustainable development of the polyimide porous material at present.
Disclosure of Invention
In order to overcome the defects of the prior art, the application aims to provide a recycling method of polyimide sponge, which is used for solving the technical problems of low preparation efficiency, difficult recycling of components, unsustainable materials and the like of the existing polyimide foam and polyimide aerogel.
In order to achieve the above purpose, the application is realized by adopting the following technical scheme:
the application discloses a cyclic regeneration method of polyimide sponge, which comprises the following steps:
s1: hydraulically fluffing polyimide sponge to obtain fiber dispersion; sequentially dehydrating and concentrating the fiber dispersion to obtain circulating water and fiber slurry A;
s2: performing pulping treatment on the fiber slurry A to obtain fiber slurry B;
s3: mixing the fiber slurry B, a surfactant, aramid nanofibers and circulating water to obtain a mixture, and performing secondary foaming on the mixture under the foam forming condition to obtain foam-fiber slurry;
s4: filtering and shaping the foam-fiber slurry, and then drying to obtain circularly regenerated polyimide sponge;
s5: and (3) processing the polyimide sponge obtained in the step (S4) through steps (S1-S4) for a plurality of times to obtain the polyimide sponge prepared through a plurality of times of circulation.
Further, in S1, the polyimide sponge is prepared by adopting a foam forming method; the hydraulic fluffing is performed in a fluffer, the rotating speed of the hydraulic fluffing is 20000 rad/min-50000 rad/min, and the mass ratio of polyimide sponge to water in the hydraulic fluffing is 0.5 g/L-5 g/L.
Further, in S2, the mass concentration of the fiber slurry A is 5-10%.
Further, in S2, the refining treatment is performed by using a PFI refiner, a disc refiner or a slot beater.
Further, when the PFI refiner is used for refining, the refining conditions are: the pulping time is 1 min-2 min, and the pulping interval is 1.5mm; when the disc mill is used for refining, the refining conditions are as follows: the pulp grinding rotating speed is 800-1500 m/min, and the pulp grinding interval is 1.5mm; when the groove type beating machine is adopted for pulping, the pulping conditions are as follows: the beating specific pressure is 0.5-2.0.
Further, in S2, the mass concentration of the fiber slurry B is 5-10%.
Further, in S3, the surfactant is one of sodium dodecyl sulfate and sodium dodecyl benzene sulfonate; the mass ratio of the fiber slurry B to the surfactant to the aramid nanofiber to the circulating water is (1-2): (0.001-0.016): (0.002-0.02): (4-8).
Further, in S3, the parameters of the secondary foaming are: the stirring speed of the foaming is 3000 rpm-5000 rpm, and the stirring time is 20 min-30 min.
Further, in S4, the parameters of the drying process are: the drying temperature is 105-110 ℃ and the drying time is 120min.
In S5, the circularly regenerated polyimide sponge obtained in S4 is subjected to steps S1-S4 for 5-10 times, and the circularly prepared polyimide sponge is obtained.
Compared with the prior art, the application has the following beneficial effects:
the application discloses a cyclic regeneration method of polyimide sponge, which adopts the combination of hydraulic fluffing and mechanical defibration, avoids using toxic and harmful polar solvents, realizes green cyclic recycling and sustainable preparation of fiber components in polyimide porous materials, and has the performance equivalent to that of raw materials. Solves the problems of low preparation efficiency, difficult component recycling, uncontinuous material and the like of the existing polyimide foam and polyimide aerogel, and provides a new method and possibility for the cyclic preparation and green sustainable development of polyimide porous materials.
Furthermore, the application also discloses the performance of the regenerated polyimide sponge obtained by the preparation method for 5 times of circulation, and related experiments prove that the performance of the polyimide sponge for 5 times of circulation disclosed by the application is equivalent to that of raw materials, and the polyimide sponge has the functions of low density, heat insulation protection, sound absorption, noise reduction, damping, vibration reduction and the like, and can realize the weight reduction, energy conservation, noise reduction and the like of large-scale equipment structures in the fields of ships, aviation, aerospace and the like.
Drawings
FIG. 1 is a schematic flow chart of the preparation of a recyclable polyimide sponge according to the present application;
FIG. 2 is a representation of a physical object during the preparation of the present application;
FIG. 3 is a comparison of the performance of the regenerated polyimide sponge after 5 cycles of example 5 of the present application.
Detailed Description
So that those skilled in the art can appreciate the features and effects of the present application, a general description and definition of the terms and expressions set forth in the specification and claims follows. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs, and in the event of a conflict, the present specification shall control.
The theory or mechanism described and disclosed herein, whether right or wrong, is not meant to limit the scope of the application in any way, i.e., the present disclosure may be practiced without limitation to any particular theory or mechanism.
All features such as values, amounts, and concentrations that are defined herein in the numerical or percent ranges are for brevity and convenience only. Accordingly, the description of a numerical range or percentage range should be considered to cover and specifically disclose all possible sub-ranges and individual values (including integers and fractions) within the range.
Herein, unless otherwise indicated, "comprising," "including," "having," or similar terms encompass the meanings of "consisting of … …" and "consisting essentially of … …," e.g., "a includes a" encompasses the meanings of "a includes a and the other and" a includes a only.
In this context, not all possible combinations of the individual technical features in the individual embodiments or examples are described in order to simplify the description. Accordingly, as long as there is no contradiction between the combinations of these technical features, any combination of the technical features in the respective embodiments or examples is possible, and all possible combinations should be considered as being within the scope of the present specification.
The application provides a cyclic regeneration method of polyimide sponge, which adopts foam forming technology, takes polyimide fiber and aramid fiber as raw materials to prepare fiber-based polyimide porous material, and takes aramid nanofiber to promote material interface bonding so as to promote material bonding strength, thus preparing polyimide/aramid fiber/aramid nanofiber ternary composite porous material; the method adopts a combination mode of hydraulic fluffing and mechanical defibration to realize the damage of hydrogen bond bonding action among polyimide porous material fibers and good dispersion of fiber components, and recycled secondary fibers are foamed again to obtain the recyclable polyimide porous material with the performance equivalent to that of raw materials, so that the problems of difficult recycling, unsustainable and the like of the conventional polyimide porous material are solved, and the simple preparation, green recycling and sustainable development of the polyimide porous material are realized.
FIG. 1 is a schematic flow chart of the application for preparing recyclable polyimide sponge, comprising the following steps:
step 1: the fiber-based polyimide porous material prepared by foam forming is placed in a fiber fluffer for hydraulic fluffing, and fiber dispersion with a certain dispersion degree is obtained by breaking hydrogen bond among fibers; carrying out dehydration treatment on the obtained fiber dispersion, and concentrating to obtain circulating water and fiber slurry A with a certain concentration;
step 2: placing the obtained fiber slurry A with a certain concentration into pulping equipment, and performing secondary dispersion treatment on the fiber slurry by controlling pulping conditions to obtain well-dispersed fiber slurry B;
step 3: adding a surfactant, aramid nanofibers and circulating water in the dehydration process into the obtained fiber slurry B, and secondarily foaming under the foam forming condition to obtain foam-fiber slurry;
step 4: transferring the obtained foam-fiber slurry into a water filtering forming container, and drying to finally obtain the recyclable polyimide sponge;
step 5: and (3) processing the obtained polyimide sponge through steps S1-S4 for a plurality of times to obtain the polyimide sponge prepared through a plurality of times of circulation.
The application will be further illustrated with reference to specific examples. It is to be understood that these examples are illustrative of the present application and are not intended to limit the scope of the present application. Furthermore, it should be understood that various changes and modifications can be made by one skilled in the art after reading the teachings of the present application, and such equivalents are intended to fall within the scope of the application as defined in the appended claims.
The following examples use instrumentation conventional in the art. The experimental methods, in which specific conditions are not noted in the following examples, are generally conducted under conventional conditions or under conditions recommended by the manufacturer. The following examples used various starting materials, unless otherwise indicated, were conventional commercial products, the specifications of which are conventional in the art. In the description of the present application and the following examples, "%" means weight percent, and "parts" means parts by weight, and ratios means weight ratio, unless otherwise specified.
Example 1
A cyclic regeneration method of polyimide sponge comprises the following steps:
step 1: the fiber-based polyimide porous material prepared by a foam forming method is placed in a fiber fluffer to be subjected to hydraulic fluffing 20000r, and fiber dispersion with a certain dispersion degree is obtained by breaking hydrogen bond bonding among fibers; carrying out dehydration treatment on the obtained fiber dispersion, and concentrating to obtain circulating water and fiber slurry A with the fiber concentration of 5%;
step 2: placing the pulp A with the fiber concentration of 5% into a PFI pulp grinder for pulp grinding treatment, grinding for 1min under the condition of a pulp grinding interval of 1.5mm, and obtaining the pulp B with the fiber concentration of 5% after the secondary dispersion treatment of the fiber pulp;
step 3: adding 0.04g of sodium dodecyl benzene sulfonate, 0.2g of aramid fiber and 160g of circulating water into the obtained fiber slurry B to obtain a mixture, regulating the fiber concentration of the mixed system to be 0.5%, and secondarily foaming the mixture under the foam forming condition for 3000r to obtain foam-fiber slurry;
step 4: transferring the foam-fiber slurry obtained in the step S4 into a water filtering forming container, and drying for 120min at 105 ℃ to finally obtain recyclable polyimide sponge;
step 5: and (3) processing the polyimide sponge obtained in the step (4) through the steps of S1-S4 for 5 times to obtain the polyimide sponge prepared through multiple times of circulation.
The recyclable polyimide porous material prepared by the implementation is detected by a multifunctional material tester and a thermal constant analyzer, and the detection results are shown in table 1.
Example 2
A cyclic regeneration method of polyimide sponge comprises the following steps:
step 1: the fiber-based polyimide porous material prepared by a foam forming method is placed in a fiber fluffer to be subjected to hydraulic fluffing 20000r, and fiber dispersion with a certain dispersion degree is obtained by breaking hydrogen bond bonding among fibers; carrying out dehydration treatment on the obtained fiber dispersion, and concentrating to obtain circulating water and fiber slurry A with the fiber concentration of 5%;
step 2: placing the pulp A with the fiber concentration of 7% into a PFI pulp grinder for pulp grinding treatment, grinding for 1min under the condition of a pulp grinding interval of 1.5mm, and obtaining the pulp B with the fiber concentration of 7% after the secondary dispersion treatment of the fiber pulp;
step 3: adding 0.2g of sodium dodecyl benzene sulfonate, 1.0g of aramid fiber and 100g of circulating water into the obtained fiber slurry B to obtain a mixture, regulating the fiber concentration of the mixed system to be 1.5%, and secondarily foaming 4000r under the foam forming condition to obtain foam-fiber slurry;
step 4: transferring the foam-fiber slurry obtained in the step S4 into a water filtering forming container, and drying for 120min at 105 ℃ to finally obtain recyclable polyimide sponge;
step 5: and (3) processing the polyimide sponge obtained in the step (4) through the steps of S1-S4 for 7 times to obtain the polyimide sponge prepared through multiple times of circulation.
The recyclable polyimide porous material prepared by the implementation is detected by a multifunctional material tester and a thermal constant analyzer, and the detection results are shown in table 1.
Example 3
A cyclic regeneration method of polyimide sponge comprises the following steps:
step 1: the fiber-based polyimide porous material prepared by a foam forming method is placed in a fiber fluffer to be hydrothermally fluffed 30000r, and fiber dispersion with a certain dispersion degree is obtained by breaking hydrogen bond bonding among fibers; carrying out dehydration treatment on the obtained fiber dispersion, and concentrating to obtain circulating water and fiber slurry A with the fiber concentration of 10%;
step 2: placing the pulp A with the fiber concentration of 10% into a PFI pulp grinder for pulp grinding treatment, grinding for 2min under the condition of a pulp grinding interval of 1.5mm, and obtaining the pulp B with the fiber concentration of 10% after the secondary dispersion treatment of the fiber pulp;
step 3: adding 0.3g of sodium dodecyl benzene sulfonate, 1.5g of aramid fiber and 50g of circulating water into the obtained fiber slurry B to obtain a mixture, regulating the fiber concentration of the mixed system to be 2.5%, and secondarily foaming under the foam forming condition for 5000r to obtain foam-fiber slurry;
step 4: transferring the foam-fiber slurry obtained in the step S4 into a water filtering forming container, and drying for 120min at 105 ℃ to finally obtain recyclable polyimide sponge;
step 5: and (3) processing the polyimide sponge obtained in the step (4) for 10 times through the steps of S1-S4 to obtain the polyimide sponge prepared through multiple times of circulation.
The recyclable polyimide porous material prepared by the implementation is detected by a multifunctional material tester and a thermal constant analyzer, and the detection results are shown in table 1.
Example 4
A cyclic regeneration method of polyimide sponge comprises the following steps:
step 1: the fiber-based polyimide porous material prepared by a foam forming method is placed in a fiber fluffer to be hydrothermally fluffed 30000r, and fiber dispersion with a certain dispersion degree is obtained by breaking hydrogen bond bonding among fibers; carrying out dehydration treatment on the obtained fiber dispersion, and concentrating to obtain circulating water and fiber slurry A with the fiber concentration of 5%;
step 2: placing the slurry A with the fiber concentration of 10% in a disc mill, pulping for 2min at the rotating speed of 800r/min, and performing secondary dispersion treatment on the fiber slurry to obtain slurry B with the fiber concentration of 5% and good dispersion;
step 3: adding 0.04g of sodium dodecyl benzene sulfonate, 0.2g of aramid fiber and 160g of circulating water into the obtained fiber slurry B to obtain a mixture, regulating the fiber concentration of the mixed system to be 0.5%, and secondarily foaming the mixture under the foam forming condition for 3000r to obtain foam-fiber slurry;
step 4: transferring the foam-fiber slurry obtained in the step S4 into a water filtering forming container, and drying for 120min at 105 ℃ to finally obtain recyclable polyimide sponge;
step 5: and (3) processing the polyimide sponge obtained in the step (4) through the steps of S1-S4 for 5 times to obtain the polyimide sponge prepared through multiple times of circulation.
The recyclable polyimide porous material prepared by the implementation is detected by a multifunctional material tester and a thermal constant analyzer, and the detection results are shown in table 1.
Example 5
A cyclic regeneration method of polyimide sponge comprises the following steps:
step 1: the fiber-based polyimide porous material prepared by a foam forming method is placed in a fiber fluffer to be subjected to hydraulic fluffing 20000r, and fiber dispersion with a certain dispersion degree is obtained by breaking hydrogen bond bonding among fibers; carrying out dehydration treatment on the obtained fiber dispersion, and concentrating to obtain circulating water and fiber slurry A with the fiber concentration of 5%;
step 2: placing the slurry A with the fiber concentration of 10% in a disc mill, pulping for 2min at the rotating speed of 1200r/min, and performing secondary dispersion treatment on the fiber slurry to obtain slurry B with the fiber concentration of 7% and good dispersion;
step 3: adding 0.2g of sodium dodecyl benzene sulfonate, 1.0g of aramid fiber and 100g of circulating water into the obtained fiber slurry B to obtain a mixture, regulating the fiber concentration of the mixed system to be 1.5%, and secondarily foaming 4000r under the foam forming condition to obtain foam-fiber slurry;
step 4: transferring the foam-fiber slurry obtained in the step S4 into a water filtering forming container, and drying for 120min at 105 ℃ to finally obtain recyclable polyimide sponge;
step 5: and (3) processing the polyimide sponge obtained in the step (4) through the steps of S1-S4 for 5 times to obtain the polyimide sponge prepared through multiple times of circulation.
The recyclable polyimide sponge prepared by the implementation is detected by a multifunctional material tester and a thermal constant analyzer, and the detection results are shown in table 1.
Example 6
A cyclic regeneration method of polyimide sponge comprises the following steps:
step 1: the fiber-based polyimide sponge prepared by the foam forming method is placed in a fiber fluffer to be hydraulically fluffed 20000r, and fiber dispersion with a certain dispersion degree is obtained by breaking hydrogen bond among fibers; carrying out dehydration treatment on the obtained fiber dispersion, and concentrating to obtain circulating water and fiber slurry A with the fiber concentration of 5%;
step 2: placing the slurry A with the fiber concentration of 10% in a disc mill, pulping for 2min at the rotating speed of 1500r/min, and performing secondary dispersion treatment on the fiber slurry to obtain slurry B with the fiber concentration of 10% and good dispersion;
step 3: adding 0.3g of sodium dodecyl benzene sulfonate, 1.5g of aramid fiber and 50g of circulating water into the obtained fiber slurry B to obtain a mixture, regulating the fiber concentration of the mixed system to be 2.5%, and secondarily foaming under the foam forming condition for 5000r to obtain foam-fiber slurry;
step 4: transferring the foam-fiber slurry obtained in the step S4 into a water filtering forming container, and drying for 120min at 105 ℃ to finally obtain recyclable polyimide sponge;
step 5: and (3) processing the polyimide sponge obtained in the step (4) for 10 times through the steps of S1-S4 to obtain the polyimide sponge prepared through multiple times of circulation.
The recyclable polyimide sponge prepared by the implementation is detected by a multifunctional material tester and a thermal constant analyzer, and the detection results are shown in table 1.
Example 7
A cyclic regeneration method of polyimide sponge comprises the following steps:
step 1: the fiber-based polyimide sponge prepared by the foam forming method is placed in a fiber fluffer to be hydrothermally fluffed for 30000r, and fiber dispersion with a certain dispersion degree is obtained by breaking hydrogen bond bonding among fibers; carrying out dehydration treatment on the obtained fiber dispersion, and concentrating to obtain circulating water and fiber slurry A with the fiber concentration of 5%;
step 2: placing the pulp A with the fiber concentration of 5% in a groove type beating machine, and performing secondary dispersion treatment on the fiber pulp under the condition of beating specific pressure of 0.5 to obtain pulp B with the fiber concentration of 5% and good dispersion;
step 3: adding 0.04g of sodium dodecyl benzene sulfonate, 0.2g of aramid fiber and 160g of circulating water into the obtained fiber slurry B to obtain a mixture, regulating the fiber concentration of the mixed system to be 0.5%, and secondarily foaming the mixture under the foam forming condition for 3000r to obtain foam-fiber slurry;
step 4: transferring the foam-fiber slurry obtained in the step S4 into a water filtering forming container, and drying for 120min at 105 ℃ to finally obtain recyclable polyimide sponge;
step 5: and (3) processing the polyimide sponge obtained in the step (4) through the steps of S1-S4 for 5 times to obtain the polyimide sponge prepared through multiple times of circulation.
The recyclable polyimide sponge prepared by the implementation is detected by a multifunctional material tester and a thermal constant analyzer, and the detection results are shown in table 1.
Example 8
A cyclic regeneration method of polyimide sponge comprises the following steps:
step 1: the fiber-based polyimide sponge prepared by the foam forming method is placed in a fiber fluffer to be hydrothermally fluffed for 30000r, and fiber dispersion with a certain dispersion degree is obtained by breaking hydrogen bond bonding among fibers; carrying out dehydration treatment on the obtained fiber dispersion, and concentrating to obtain circulating water and fiber slurry A with the fiber concentration of 7%;
step 2: placing the pulp A with the fiber concentration of 7% in a groove type beating machine, and carrying out secondary dispersion treatment on the fiber pulp under the condition of beating specific pressure of 1.0 to obtain pulp B with the fiber concentration of 7% and good dispersion;
step 3: adding 0.2g of sodium dodecyl benzene sulfonate, 1.0g of aramid fiber and 100g of circulating water into the obtained fiber slurry B to obtain a mixture, regulating the fiber concentration of the mixed system to be 1.5%, and secondarily foaming 4000r under the foam forming condition to obtain foam-fiber slurry;
step 4: transferring the foam-fiber slurry obtained in the step S4 into a water filtering forming container, and drying for 120min at 105 ℃ to finally obtain recyclable polyimide sponge;
step 5: and (3) processing the polyimide sponge obtained in the step (4) through the steps of S1-S4 for 7 times to obtain the polyimide sponge prepared through multiple times of circulation.
The recyclable polyimide sponge prepared by the implementation is detected by a multifunctional material tester and a thermal constant analyzer, and the detection results are shown in table 1.
Example 9
A cyclic regeneration method of polyimide sponge comprises the following steps:
step 1: the fiber-based polyimide sponge prepared by the foam forming method is placed in a fiber fluffer to be hydraulically fluffed 20000r, and fiber dispersion with a certain dispersion degree is obtained by breaking hydrogen bond among fibers; carrying out dehydration treatment on the obtained fiber dispersion, and concentrating to obtain circulating water and fiber slurry A with the fiber concentration of 10%;
step 2: placing the pulp A with the fiber concentration of 10% in a groove type beating machine, and carrying out secondary dispersion treatment on the fiber pulp under the condition of beating specific pressure of 2.0 to obtain pulp B with the fiber concentration of 10% and good dispersion;
step 3: adding 0.3g of sodium dodecyl benzene sulfonate, 1.5g of aramid fiber and 50g of circulating water into the obtained fiber slurry B to obtain a mixture, regulating the fiber concentration of the mixed system to be 2.5%, and secondarily foaming under the foam forming condition for 5000r to obtain foam-fiber slurry;
step 4: transferring the foam-fiber slurry obtained in the step S4 into a water filtering forming container, and drying for 120min at 105 ℃ to finally obtain recyclable polyimide sponge;
step 5: and (3) processing the polyimide sponge obtained in the step (4) for 10 times through the steps of S1-S4 to obtain the polyimide sponge prepared through multiple times of circulation.
The recyclable polyimide sponge prepared by the implementation is detected by a multifunctional material tester and a thermal constant analyzer, and the detection results are shown in table 1.
Table 1 detection of the properties of the regenerated polyimide sponge under different examples
As can be seen from Table 1, when the amounts of the aramid nanofibers are the same (2%, 6% and 10%), the properties of the regenerated polyimide sponge prepared by the three different mechanical defibration modes are close, which indicates that the different mechanical defibration modes in the application can realize fiber recycling and material regeneration; when the amount of the aramid nanofibers is close to the condition of the comparative raw material, the performance of the circularly regenerated polyimide sponge is equivalent to that of the raw material, and after 5 times of circulation, the performance of the regenerated material is still close to that of the raw material (figure 3). The method disclosed by the application is used for destroying the physical bonding among fibers through hydraulic fluffing, and realizing hydrogen bond destruction among fibers through mechanical defibration, so that good dispersion and recycling of the fibers are realized, the properties of the fibers are not damaged, and the regenerated polyimide sponge with the properties close to those can be obtained when the conditions of the preparation process of the circulating material and the preparation process of the raw material are the same. Further proves that the method has good universality and applicability in the aspect of preparing the recyclable polyimide sponge, and can solve the problems of difficult recycling, unsustainable and the like of the polyimide sponge at present.
Fig. 2 shows a physical display in the preparation process of the present application, and as can be seen from fig. 2, the polyimide sponge prepared by the foam forming method can achieve destruction of hydrogen bonding action between fibers through hydraulic fluffing and mechanical defibration, and destroy physical bonding between fibers in a high-speed dispersion process, so as to achieve recycling of polyimide fibers and aramid fibers, and the foam forming method is adopted to foam secondary fibers recycled for multiple times, so that the prepared renewable circulating sponge has a structure and performance similar to those of the original polyimide sponge.
The above is only for illustrating the technical idea of the present application, and the protection scope of the present application is not limited by this, and any modification made on the basis of the technical scheme according to the technical idea of the present application falls within the protection scope of the claims of the present application.
Claims (6)
1. The cyclic regeneration method of the polyimide sponge is characterized by comprising the following steps of:
s1: hydraulically fluffing polyimide sponge to obtain fiber dispersion; sequentially dehydrating and concentrating the fiber dispersion to obtain circulating water and fiber slurry A;
in S1, the polyimide sponge is prepared by adopting a foam forming method; the hydraulic fluffing is performed in a fluffer, the rotating speed of the hydraulic fluffing is 20000 rad/min-50000 rad/min, and the mass ratio of polyimide sponge to water in the hydraulic fluffing is 0.5 g/L-5 g/L;
s2: performing pulping treatment on the fiber slurry A to obtain fiber slurry B;
s2, pulping treatment is carried out by adopting a PFI (pulse frequency reactor) pulping machine, a disc mill or a groove type pulping machine;
when the pulp refining treatment is carried out by adopting a PFI pulp refiner, the pulp refining conditions are as follows: the pulping time is 1 to 2 minutes, and the pulping interval is 1.5mm; when the disc mill is used for refining, the refining conditions are as follows: the pulp grinding rotating speed is 800-1500 m/min, and the pulp grinding interval is 1.5mm; when the groove type beating machine is adopted for pulping, the pulping conditions are as follows: the beating specific pressure is 0.5-2.0;
s3: mixing the fiber slurry B, a surfactant, aramid nanofibers and circulating water to obtain a mixture, and performing secondary foaming on the mixture under the foam forming condition to obtain foam-fiber slurry;
s4: filtering and shaping the foam-fiber slurry, and then drying to obtain circularly regenerated polyimide sponge;
s5: the circularly regenerated polyimide sponge obtained in the step S4 is subjected to multiple steps of S1-S4, and the polyimide sponge prepared through multiple times of circulation is obtained;
and S5, processing the circularly regenerated polyimide sponge obtained in the step S4 through steps S1-S4 for 5-10 times to obtain the repeatedly circularly prepared polyimide sponge.
2. The recycling method of polyimide sponge according to claim 1, wherein in S2, the mass concentration of the fiber slurry A is 5% -10%.
3. The recycling method of polyimide sponge according to claim 1, wherein in S2, the mass concentration of the fiber slurry B is 5% -10%.
4. The method for recycling polyimide sponge according to claim 1, wherein in S3, the surfactant is one of sodium dodecyl sulfate and sodium dodecyl benzene sulfonate; the mass ratio of the fiber slurry B to the surfactant to the aramid nanofiber to the circulating water is (1-2): (0.001-0.016): (0.002-0.02): (4-8).
5. The recycling method of polyimide sponge according to claim 1, wherein in S3, the technological parameters of the secondary foaming are as follows: the stirring speed of the foaming is 3000-5000 rpm, and the stirring time is 20-30 min.
6. The method for recycling polyimide sponge according to claim 1, wherein in S4, the parameters of the drying process are: the drying temperature is 105-110 ℃ and the drying time is 120min.
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| CN102899959A (en) * | 2012-09-27 | 2013-01-30 | 陕西科技大学 | Para-position aramid fiber paper used for cellular material and preparation method thereof |
| KR101479756B1 (en) * | 2013-08-01 | 2015-01-06 | (주)에프티이앤이 | Multi-layered nanofiber filter with excellent heat-resisting property and its method |
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