CN114920974A - Cyclic regeneration method of polyimide sponge - Google Patents
Cyclic regeneration method of polyimide sponge Download PDFInfo
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- CN114920974A CN114920974A CN202210744293.9A CN202210744293A CN114920974A CN 114920974 A CN114920974 A CN 114920974A CN 202210744293 A CN202210744293 A CN 202210744293A CN 114920974 A CN114920974 A CN 114920974A
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- 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
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- 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 invention discloses a recycling method of polyimide sponge, belongs to the technical field of polyimide porous materials, and solves the technical problems that existing polyimide foams and polyimide aerogel are low in preparation efficiency, difficult in component recycling, non-sustainable in materials and the like. According to the method for recycling the polyimide sponge, disclosed by the invention, hydraulic defibering and mechanical defibering are combined, so that a toxic and harmful polar solvent is avoided, green recycling and sustainable preparation of fiber components in the polyimide porous material are realized, and the performance of the polyimide porous material prepared in a recycling manner is equivalent to that of a raw material; the method solves the problems of low preparation efficiency, difficult component recycling, non-sustainable material and the like of the existing polyimide foam and polyimide aerogel, and provides a new method and possibility for the cyclic preparation and the green sustainable development of the polyimide porous material.
Description
Technical Field
The invention belongs to the technical field of polyimide porous materials, and particularly relates to a cyclic regeneration method of polyimide sponge.
Background
Porous materials such as polyimide foam and aerogel have high porosity and excellent heat insulation and sound absorption characteristics, and are important basic materials for realizing the development of large-scale, light-weight and green carrying equipment in the fields of rail transit and aerospace navigation. However, the existing polyimide foam and aerogel porous materials have the problems of low preparation efficiency, difficult recycling, unsustainability and the like, and provide challenges for green preparation and sustainable development of the materials. The development of a green recyclable polyimide porous material preparation technology has important significance for promoting the sustainable development of materials, further widening the application field and promoting the energy-saving and noise-reducing and low-carbon and carbon-reducing development of large-scale equipment.
The main forms of polyimide porous materials include the following two: polyimide foam and polyimide aerogel.
1) Polyimide foam
Currently, polyimide foams are mainly prepared in one or two steps. Research shows that the one-step method for preparing the polyimide foam has simple process and easy operation of instruments and equipment. Polyimide foam is prepared from aromatic dianhydride and triphenylmethane triisocyanate adhesive by one-step method, and CO generated in the process is adopted 2 As a foaming agent, the influence of byproducts on the mechanical strength and the thermal stability of the foam is avoided, but the polyimide foam prepared by the one-step method has lower apparent density and heat-insulating property; when the polyimide sponge is prepared by adopting the two-step method, although the prepared foam has the characteristics of high density, high compressive strength and good heat-insulating property, the prepared foam has a non-uniform cell structure and a complex preparation process.
2) Polyimide aerogel
Except for common solventsBesides preparing polyimide foam by a foaming method, the polyimide aerogel is also an important polyimide porous heat-insulating material. Wherein, CO 2 Supercritical drying, normal pressure drying, freeze drying and other drying processes are important factors influencing the structure and the performance of the polyimide aerogel; due to the limitations of supercritical drying in terms of preparation conditions and sample size, its application is limited. At present, freeze drying is also one of the most important means for preparing polyimide aerogel, and polyimide ammonium salt/clay mixed suspension is subjected to freeze drying and imidization 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 Meanwhile, with the increase of the PI content, the composite material presents a more perfect 'layer-branch' supporting structure, and the compression modulus of the composite material is improved by 5-50 times compared with that of the unmodified clay aerogel.
Although polyimide foams prepared by the methods of one-step method and two-step method, polyimide aerogels prepared by the methods of supercritical drying, freeze drying and the like have the characteristics of light weight, heat insulation and sound absorption, the above methods inevitably have the problems of low preparation efficiency, difficult recycling of components, non-sustainable materials and the like. The problem of sustainable development of the polyimide porous material is solved by avoiding using toxic and harmful polar solvents, efficiently recycling components of the polyimide porous material in a green way and circularly preparing the polyimide porous material.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a method for recycling polyimide sponge, which is used for solving the technical problems of low preparation efficiency, difficult component recycling, non-sustainable materials and the like of the existing polyimide foams and polyimide aerogels.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
the invention discloses a cyclic regeneration method of polyimide sponge, which comprises the following steps:
s1: performing hydraulic defibering on polyimide sponge to obtain a fiber dispersoid; sequentially dehydrating and concentrating the fiber dispersoid to obtain circulating water and fiber slurry A;
s2: carrying out pulping treatment on the fiber pulp A to obtain fiber pulp B;
s3: mixing the fiber slurry B, a surfactant, aramid nano-fibers and circulating water to obtain a mixture, and carrying out secondary foaming on the mixture under a foam forming condition to obtain foam-fiber slurry;
s4: filtering and forming the foam-fiber slurry, and then drying to obtain a circularly regenerated polyimide sponge;
s5: and (3) processing the polyimide sponge obtained in the step S4 through the steps S1-S4 for multiple times to obtain the polyimide sponge prepared through multiple cycles.
Further, in S1, the polyimide sponge is prepared by a foam forming method; the hydraulic defibering is carried out in a defibering machine, the rotating speed of the hydraulic defibering is 20000rad/min to 50000rad/min, and the mass ratio of the polyimide sponge to the water in the hydraulic defibering is 0.5g/L to 5 g/L.
Further, in S2, the mass concentration of the fiber slurry a is 5% to 10%.
Further, in S2, the refining process is performed using a PFI refiner, a disc refiner, or a trough refiner.
Further, when the refining process is performed using a PFI refiner, the refining conditions are: the pulping time is 1 min-2 min, and the pulping interval is 1.5 mm; when a disc mill is adopted for refining, the refining conditions are as follows: the grinding rotation speed is 800 m/min-1500 m/min, and the grinding distance is 1.5 mm; when a trough type beater is adopted for pulping, the pulping conditions are as follows: the pulping specific pressure is 0.5-2.0.
Further, in S2, the mass concentration of the fiber slurry B is 5% to 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, the surfactant, the aramid nano-fiber and 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 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 120 min.
Further, in S5, the circularly regenerated polyimide sponge obtained in S4 is subjected to the steps of S1 to S4 for 5 to 10 times to obtain the polyimide sponge prepared in multiple cycles.
Compared with the prior art, the invention has the following beneficial effects:
the invention discloses a cyclic regeneration method of polyimide sponge, which combines hydraulic defibering and mechanical defibering to avoid using toxic and harmful polar solvents, realize green cyclic recycling and sustainable preparation of fiber components in a polyimide porous material, and the performance of the polyimide porous material prepared cyclically is equivalent to that of raw materials. The method solves the problems of low preparation efficiency, difficult component recycling, non-sustainable material and the like of the existing polyimide foam and polyimide aerogel, and provides a new method and possibility for the cyclic preparation and the green sustainable development of the polyimide porous material.
Furthermore, the invention also discloses the performance of the regenerated polyimide sponge obtained by adopting the preparation method for 5 times of circulation, and related experiments prove that the performance of the polyimide sponge disclosed by the invention for 5 times of circulation is equivalent to that of raw materials, and the polyimide sponge has the functions of low density, thermal insulation protection, sound absorption and noise reduction, damping and vibration reduction and the like, and can realize weight reduction, energy saving and noise reduction of large equipment structures in the fields of ships, aviation, aerospace and the like.
Drawings
FIG. 1 is a schematic flow diagram of the present invention for preparing recyclable polyimide sponge;
FIG. 2 is a physical display of the present invention during the preparation process;
FIG. 3 is a comparison of the properties of the regenerated polyimide sponge of example 5 of the present invention after 5 cycles.
Detailed Description
To make the features and effects of the present invention comprehensible to those skilled in the art, general description and definitions are made below with reference to terms and expressions mentioned in the specification and claims. Unless defined otherwise, 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 invention belongs.
The theory or mechanism described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, i.e., the present disclosure may be practiced without being limited by any particular theory or mechanism.
All features defined herein as numerical ranges or percentage ranges, such as values, amounts, levels and concentrations, are provided for brevity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to cover and specifically disclose all possible subranges and individual numerical values (including integers and fractions) within the range.
Unless otherwise specified herein, "comprising," including, "" containing, "" having, "or the like, means" consisting of … … "and" consisting essentially of … …, "e.g.," a comprises a "means" a comprises a and the other, "and" a comprises a only.
In the present context, for the sake of brevity, all possible combinations of various features in various embodiments or examples are not described. Therefore, the respective features in the respective embodiments or examples may be arbitrarily combined as long as there is no contradiction between the combinations of the features, and all the possible combinations should be considered as the scope of the present specification.
The invention provides a cyclic regeneration method of polyimide sponge, which adopts a foam forming technology, takes polyimide fibers and aramid fibers as raw materials to prepare a fiber-based polyimide porous material, and uses aramid nano-fibers to promote the interface bonding of the material so as to improve the bonding strength of the material, so as to prepare a polyimide/aramid fiber/aramid nano-fiber ternary composite porous material; the method adopts a mode of combining hydraulic defibering and mechanical defibering to realize the damage of the hydrogen bond bonding action between the fibers of the polyimide porous material and the good dispersion of the fiber components, and recycled secondary fibers are foamed again to obtain the recyclable polyimide porous material with the performance equivalent to that of the raw materials, so that the problems of difficult recycling, unsustainable property and the like of the existing 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 preparation of recyclable polyimide sponge according to the present invention, which comprises the following steps:
step 1: placing the fiber-based polyimide porous material prepared by foam forming in a defiberizing machine for hydraulic defibering, and obtaining a fiber dispersion with a certain dispersion degree by breaking hydrogen bond bonding between fibers; dehydrating the obtained fiber dispersoid, and concentrating to obtain circulating water and fiber slurry A with certain concentration;
step 2: placing the obtained fiber pulp A with a certain concentration in pulping equipment, and performing secondary dispersion treatment on the fiber pulp by controlling pulping conditions to obtain well-dispersed fiber pulp B;
and step 3: adding a surfactant, aramid nano-fibers and circulating water in a dehydration process into the obtained fiber slurry B, and carrying out secondary foaming under a foam forming condition to obtain foam-fiber slurry;
and 4, step 4: transferring the obtained foam-fiber slurry into a water-filtering forming container, and drying to finally obtain the recyclable polyimide sponge;
and 5: and (3) processing the obtained polyimide sponge by multiple steps of S1-S4 to obtain the polyimide sponge prepared by multiple cycles.
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.
The following examples use instrumentation conventional in the art. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out under conventional conditions or conditions recommended by the manufacturers. The various starting materials used in the examples which follow, unless otherwise indicated, are conventional commercial products having specifications which are conventional in the art. In the description of the present invention and the following examples, "%" represents weight percent, "parts" represents parts by weight, and proportions represent weight ratios, unless otherwise specified.
Example 1
A cyclic regeneration method of polyimide sponge comprises the following steps:
step 1: placing the fiber-based polyimide porous material prepared by a foam forming method in a defibering machine for hydro-defibering 20000r, and obtaining a fiber dispersion with a certain dispersion degree by breaking hydrogen bond bonding between fibers; dehydrating 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 PFI pulp grinder to grind for 1min under the condition that the grinding distance is 1.5mm, and obtaining the pulp B with good dispersion and the fiber concentration of 5% after the secondary dispersion treatment of the fiber pulp;
and 3, step 3: adding 0.04g of sodium dodecyl benzene sulfonate, 0.2g of aramid nano fiber and 160g of circulating water into the obtained fiber slurry B to obtain a mixture, regulating and controlling the fiber concentration of a mixed system to be 0.5%, and performing secondary foaming for 3000r under a foam forming condition to obtain foam-fiber slurry;
and 4, 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 the recyclable polyimide sponge;
and 5: and (5) processing the polyimide sponge obtained in the step (4) for 5 times through the steps from S1 to S4 to obtain the polyimide sponge prepared through multiple cycles.
The recyclable polyimide porous material prepared by the method is detected by a multifunctional material testing machine and a thermal constant analyzer, and the detection result is shown in table 1.
Example 2
A cyclic regeneration method of polyimide sponge comprises the following steps:
step 1: placing the fiber-based polyimide porous material prepared by a foam forming method in a defibering machine for hydro-defibering 20000r, and obtaining a fiber dispersion with a certain dispersion degree by breaking hydrogen bond bonding between fibers; dehydrating the obtained fiber dispersoid, 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% in a PFI pulp grinder to grind for 1min under the condition that the grinding distance is 1.5mm, and obtaining the pulp B with good dispersion and the fiber concentration of 7% after the secondary dispersion treatment of the fiber pulp;
and step 3: adding 0.2g of sodium dodecyl benzene sulfonate, 1.0g of aramid nano fiber and 100g of circulating water into the obtained fiber slurry B to obtain a mixture, regulating and controlling the fiber concentration of a mixed system to be 1.5%, and performing secondary foaming for 4000r under a foam forming condition to obtain foam-fiber slurry;
and 4, 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 the recyclable polyimide sponge;
and 5: and (4) processing the polyimide sponge obtained in the step (4) for 7 times through steps S1-S4 to obtain the polyimide sponge prepared through multiple cycles.
The recyclable polyimide porous material prepared by the implementation is detected by a multifunctional material testing machine and a thermal constant analyzer, and the detection result is shown in table 1.
Example 3
A cyclic regeneration method of polyimide sponge comprises the following steps:
step 1: placing the fiber-based polyimide porous material prepared by a foam forming method in a fiber fluffer for hydraulic fluffing at 30000r, and obtaining a fiber dispersion with a certain dispersion degree by breaking hydrogen bond bonding between fibers; dehydrating the obtained fiber dispersoid, 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 PFI pulping machine for pulping, pulping for 2min under the condition that the pulping interval is 1.5mm, and performing secondary dispersion treatment on the fiber pulp to obtain well-dispersed pulp B with the fiber concentration of 10%;
and 3, step 3: adding 0.3g of sodium dodecyl benzene sulfonate, 1.5g of aramid nano fiber and 50g of circulating water into the obtained fiber slurry B to obtain a mixture, regulating and controlling the fiber concentration of a mixed system to be 2.5%, and performing secondary foaming for 5000r under a foam forming condition to obtain foam-fiber slurry;
and 4, 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 the recyclable polyimide sponge;
and 5: and (4) processing the polyimide sponge obtained in the step (4) for 10 times through steps S1-S4 to obtain the polyimide sponge prepared through multiple cycles.
The recyclable polyimide porous material prepared by the implementation is detected by a multifunctional material testing machine and a thermal constant analyzer, and the detection result is shown in table 1.
Example 4
A cyclic regeneration method of polyimide sponge comprises the following steps:
step 1: placing the fiber-based polyimide porous material prepared by a foam forming method in a fiber fluffer for hydraulic fluffing at 30000r, and obtaining a fiber dispersion with a certain dispersion degree by breaking hydrogen bond bonding between fibers; dehydrating the obtained fiber dispersoid, 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 10% in a disc grinder, grinding the pulp for 2min under the condition that the rotating speed of the disc grinder is 800r/min, and performing secondary dispersion treatment on the fiber pulp to obtain the pulp B with good dispersion and the fiber concentration of 5%;
and 3, step 3: adding 0.04g of sodium dodecyl benzene sulfonate, 0.2g of aramid nano fiber and 160g of circulating water into the obtained fiber slurry B to obtain a mixture, regulating and controlling the fiber concentration of a mixed system to be 0.5%, and performing secondary foaming for 3000r under a foam forming condition to obtain foam-fiber slurry;
and 4, 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 the recyclable polyimide sponge;
and 5: and (5) processing the polyimide sponge obtained in the step (4) for 5 times through the steps from S1 to S4 to obtain the polyimide sponge prepared through multiple cycles.
The recyclable polyimide porous material prepared by the method is detected by a multifunctional material testing machine and a thermal constant analyzer, and the detection result is shown in table 1.
Example 5
A cyclic regeneration method of polyimide sponge comprises the following steps:
step 1: placing the fiber-based polyimide porous material prepared by a foam forming method in a defibering machine for hydro-defibering 20000r, and obtaining a fiber dispersion with a certain dispersion degree by breaking hydrogen bond bonding between fibers; dehydrating the obtained fiber dispersoid, and concentrating to obtain circulating water and fiber slurry A with the fiber concentration of 5%;
and 2, step: placing the pulp A with the fiber concentration of 10% in a disc grinder, grinding the pulp for 2min under the condition that the rotating speed of the disc grinder is 1200r/min, and performing secondary dispersion treatment on the fiber pulp to obtain the pulp B with good dispersion and the fiber concentration of 7%;
and 3, step 3: adding 0.2g of sodium dodecyl benzene sulfonate, 1.0g of aramid nano fiber and 100g of circulating water into the obtained fiber slurry B to obtain a mixture, regulating and controlling the fiber concentration of a mixed system to be 1.5%, and carrying out secondary foaming for 4000r under a foam forming condition to obtain foam-fiber slurry;
and 4, 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 the recyclable polyimide sponge;
and 5: and (4) processing the polyimide sponge obtained in the step (4) for 5 times through steps S1-S4 to obtain the polyimide sponge prepared through multiple cycles.
The recyclable polyimide sponge prepared by the implementation is detected by a multifunctional material testing machine and a thermal constant analyzer, and the detection result is shown in table 1.
Example 6
A cyclic regeneration method of polyimide sponge comprises the following steps:
step 1: placing the fiber-based polyimide sponge prepared by a foam forming method in a defibering machine for hydro-defibering 20000r, and obtaining a fiber dispersion with a certain dispersion degree by breaking hydrogen bond bonding between fibers; dehydrating the obtained fiber dispersoid, and concentrating to obtain circulating water and fiber slurry A with the fiber concentration of 5%;
and 2, step: placing the pulp A with the fiber concentration of 10% in a disc grinder, grinding the pulp for 2min under the condition that the rotating speed of the disc grinder is 1500r/min, and performing secondary dispersion treatment on the fiber pulp to obtain the pulp B with good dispersion and the fiber concentration of 10%;
and 3, step 3: adding 0.3g of sodium dodecyl benzene sulfonate, 1.5g of aramid nano fiber and 50g of circulating water into the obtained fiber slurry B to obtain a mixture, regulating and controlling the fiber concentration of a mixed system to be 2.5%, and performing secondary foaming for 5000r under a foam forming condition to obtain foam-fiber slurry;
and 4, 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 the recyclable polyimide sponge;
and 5: and (5) processing the polyimide sponge obtained in the step (4) for 10 times through the steps from S1 to S4 to obtain the polyimide sponge prepared through multiple cycles.
The recyclable polyimide sponge prepared by the implementation is detected by a multifunctional material testing machine and a thermal constant analyzer, and the detection result is shown in table 1.
Example 7
A cyclic regeneration method of polyimide sponge comprises the following steps:
step 1: placing the fiber-based polyimide sponge prepared by a foam forming method in a fiber fluffer for hydraulic fluffing for 30000r, and obtaining a fiber dispersion with a certain dispersion degree by breaking hydrogen bond bonding between fibers; dehydrating 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 5% in a groove type beating machine, and performing secondary dispersion treatment on the fiber slurry to obtain a slurry B with good dispersion and the fiber concentration of 5% under the condition of beating specific pressure of 0.5;
and 3, step 3: adding 0.04g of sodium dodecyl benzene sulfonate, 0.2g of aramid nano fiber and 160g of circulating water into the obtained fiber slurry B to obtain a mixture, regulating and controlling the fiber concentration of a mixed system to be 0.5%, and performing secondary foaming for 3000r under a foam forming condition to obtain foam-fiber slurry;
and 4, 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 the recyclable polyimide sponge;
and 5: and (4) processing the polyimide sponge obtained in the step (4) for 5 times through steps S1-S4 to obtain the polyimide sponge prepared through multiple cycles.
The recyclable polyimide sponge prepared by the implementation is detected by a multifunctional material testing machine and a thermal constant analyzer, and the detection result is shown in table 1.
Example 8
A cyclic regeneration method of polyimide sponge comprises the following steps:
step 1: placing the fiber-based polyimide sponge prepared by a foam forming method in a defiberizing machine for hydraulic defibering for 30000r, and obtaining a fiber dispersion with a certain dispersion degree by breaking hydrogen bond bonding between fibers; dehydrating the obtained fiber dispersoid, and concentrating to obtain circulating water and fiber slurry A with the fiber concentration of 7%;
and 2, step: placing the pulp A with the fiber concentration of 7% in a trough type beating machine, and performing secondary dispersion treatment on the fiber pulp to obtain well-dispersed pulp B with the fiber concentration of 7% under the condition of beating specific pressure of 1.0;
and step 3: adding 0.2g of sodium dodecyl benzene sulfonate, 1.0g of aramid nano fiber and 100g of circulating water into the obtained fiber slurry B to obtain a mixture, regulating and controlling the fiber concentration of a mixed system to be 1.5%, and performing secondary foaming for 4000r under a foam forming condition to obtain foam-fiber slurry;
and 4, step 4: transferring the foam-fiber slurry obtained in the step S4 into a drainage forming container, and drying for 120min at 105 ℃ to finally obtain recyclable polyimide sponge;
and 5: and (4) processing the polyimide sponge obtained in the step (4) for 7 times through steps S1-S4 to obtain the polyimide sponge prepared through multiple cycles.
The recyclable polyimide sponge prepared by the implementation method is detected by using a multifunctional material testing machine and a thermal constant analyzer, and the detection result is shown in table 1.
Example 9
A cyclic regeneration method of polyimide sponge comprises the following steps:
step 1: placing the fiber-based polyimide sponge prepared by a foam forming method in a defiberizing machine for hydro-defibering 20000r, and obtaining a fiber dispersion with a certain dispersion degree by breaking hydrogen bond bonding between fibers; dehydrating the obtained fiber dispersoid, 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 trough type beating machine, and performing secondary dispersion treatment on the fiber pulp to obtain well-dispersed pulp B with the fiber concentration of 10% under the condition of beating specific pressure of 2.0;
and step 3: adding 0.3g of sodium dodecyl benzene sulfonate, 1.5g of aramid nano fiber and 50g of circulating water into the obtained fiber slurry B to obtain a mixture, regulating and controlling the fiber concentration of a mixed system to be 2.5%, and performing secondary foaming for 5000r under a foam forming condition to obtain foam-fiber slurry;
and 4, 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 the recyclable polyimide sponge;
and 5: and (4) processing the polyimide sponge obtained in the step (4) for 10 times through steps S1-S4 to obtain the polyimide sponge prepared through multiple cycles.
The recyclable polyimide sponge prepared by the implementation method is detected by using a multifunctional material testing machine and a thermal constant analyzer, and the detection result is shown in table 1.
TABLE 1 testing of properties of regenerated polyimide sponges in different examples
As can be seen from table 1, when the dosages of the aramid nanofibers are the same (2%, 6%, 10%), the properties of the regenerated polyimide sponge prepared by three different mechanical defibering modes are close to each other, which indicates that the different mechanical defibering modes in the content of the invention can realize fiber recycling and material regeneration; when the dosage of the aramid nano-fiber is close to the conditions of the comparative raw materials, the performance of the polyimide sponge regenerated in a circulating way is equivalent to that of the raw materials, and after 5 times of circulation, the performance of the regenerated material is still close to that of the raw materials (figure 3). The method of the invention breaks physical combination among fibers through hydraulic defibering and realizes hydrogen bond destruction among fibers through mechanical defibering, thereby realizing good dispersion and recycling of the fibers, simultaneously not damaging the performance of the fibers, and obtaining the regenerated polyimide sponge with similar performance when ensuring that the conditions of the preparation process of the circulating material and the preparation process of raw materials are the same. The method has good universality and applicability in the aspect of preparing recyclable polyimide sponge, and can solve the problems that the existing polyimide sponge is difficult to recycle and is not sustainable and the like.
Fig. 2 shows a real object in the preparation process of the present invention, and as can be seen from fig. 2, the polyimide sponge prepared by the foam forming method can realize the destruction of the hydrogen bond bonding between fibers through the hydraulic defibering and mechanical defibering processes, and destroy the physical bonding between fibers in the high-speed dispersion process, so as to realize the recycling of the polyimide fibers and the aramid fibers, and the foam forming method is adopted to foam the secondary fibers recycled for many times, so that the prepared renewable cyclic sponge has a structure and performance close to those of the original polyimide sponge.
The above contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention should not be limited thereby, and any modification made on the basis of the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.
Claims (10)
1. A cyclic regeneration method of polyimide sponge is characterized by comprising the following steps:
s1: performing hydraulic defibering on polyimide sponge to obtain a fiber dispersion; sequentially dehydrating and concentrating the fiber dispersoid to obtain circulating water and fiber slurry A;
s2: carrying out pulping treatment on the fiber pulp A to obtain fiber pulp B;
s3: mixing the fiber pulp B, a surfactant, aramid nano-fibers and circulating water to obtain a mixture, and carrying out secondary foaming on the mixture under a foam forming condition to obtain foam-fiber pulp;
s4: filtering and forming the foam-fiber slurry, and then drying to obtain a circularly regenerated polyimide sponge;
s5: and (3) processing the recycled and regenerated polyimide sponge obtained in the step S4 through the steps S1-S4 for multiple times to obtain the polyimide sponge prepared through multiple times of recycling.
2. The recycling method of polyimide sponge according to claim 1, wherein in S1, the polyimide sponge is prepared by foam forming; the hydraulic defibering is carried out in a defibering machine, the rotating speed of the hydraulic defibering is 20000rad/min to 50000rad/min, and the mass ratio of the polyimide sponge to the water in the hydraulic defibering is 0.5g/L to 5 g/L.
3. The recycling method of polyimide sponge as claimed in claim 1, wherein in S2, the mass concentration of the fiber slurry A is 5-10%.
4. The recycling method of polyimide sponge as claimed in claim 1, wherein in step S2, the refining process is performed by PFI refiner, disc refiner or trough refiner.
5. The recycling method of polyimide sponge according to claim 4, wherein when the refining process is performed by PFI refiner, the refining conditions are as follows: the pulping time is 1 min-2 min, and the pulping interval is 1.5 mm; when a disc mill is adopted for refining, the refining conditions are as follows: the grinding speed is 800-1500 m/min, and the grinding distance is 1.5 mm; when a trough type beater is adopted for pulping, the pulping conditions are as follows: the pulping specific pressure is 0.5-2.0.
6. The recycling method of polyimide sponge according to claim 1, wherein in S2, the mass concentration of the fiber slurry B is 5-10%.
7. The method of 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, the surfactant, the aramid nano-fiber and the circulating water is (1-2): (0.001-0.016): (0.002-0.02): (4-8).
8. The recycling method of polyimide sponge as claimed in claim 1, wherein in S3, the process parameters of the secondary foaming are: the stirring speed of foaming is 3000 rpm-5000 rpm, and the stirring time is 20 min-30 min.
9. The method for recycling polyimide sponge according to claim 1, wherein in S4, the drying parameters are: the drying temperature is 105-110 ℃, and the drying time is 120 min.
10. The recycling method of polyimide sponges as claimed in claim 1, wherein in S5, the recycled polyimide sponge obtained in S4 is further processed through steps S1-S4 for 5-10 times to obtain polyimide sponges prepared in multiple recycling manners.
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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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| CN113717429A (en) * | 2021-08-11 | 2021-11-30 | 复旦大学 | Ultra-light multifunctional polyimide-based nano composite aerogel material and preparation method thereof |
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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 |
| CN105220262A (en) * | 2015-08-24 | 2016-01-06 | 江苏先诺新材料科技有限公司 | A kind of polyimides (PI) pulp and preparation method thereof |
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