CN116218132A - Electromagnetic wave absorbing foam and preparation method thereof - Google Patents
Electromagnetic wave absorbing foam and preparation method thereof Download PDFInfo
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- CN116218132A CN116218132A CN202111511981.2A CN202111511981A CN116218132A CN 116218132 A CN116218132 A CN 116218132A CN 202111511981 A CN202111511981 A CN 202111511981A CN 116218132 A CN116218132 A CN 116218132A
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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
- C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
- C08J9/06—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent
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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
- C08J9/0066—Use of inorganic compounding ingredients
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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
- C08J2361/00—Characterised by the use of condensation polymers of aldehydes or ketones; Derivatives of such polymers
- C08J2361/04—Condensation polymers of aldehydes or ketones with phenols only
- C08J2361/06—Condensation polymers of aldehydes or ketones with phenols only of aldehydes with phenols
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Abstract
The invention provides an electromagnetic wave absorption foam and a preparation method thereof. The preparation method comprises the following steps: step S1, mixing liquid phenolic resin, a diluent and a stabilizer to form a liquid resin mixture; step S2, stirring the liquid resin mixture, and then adding pentacarbonyl iron in a stirring state to obtain a liquid precursor; and S3, pouring a liquid precursor into the mold, heating to a first temperature under inert gas to decompose iron pentacarbonyl, and then continuously heating to a second temperature to solidify the liquid phenolic resin to obtain the electromagnetic wave absorption foam. The wave-absorbing foam wave-absorbing agent prepared by the invention has uniform distribution, less electromagnetic wave secondary interference and better wave-absorbing performance.
Description
Technical Field
The invention relates to the field of wave absorbing materials, in particular to electromagnetic wave absorbing foam and a preparation method thereof.
Background
In recent years, with the rapid development of the electronic information industry, various electronic and electric equipment provide great help for daily life and social construction of people. Meanwhile, the problems of electromagnetic radiation and interference generated in the working process of electronic and electric equipment restrict the production and life of people, so that the electromagnetic pollution of human living space is also serious, and the electromagnetic pollution becomes fourth pollution after noise pollution, water pollution and atmosphere pollution. Electromagnetic waves in various frequency bands in the space seriously affect the health of human beings and the normal operation of communication equipment. Therefore, it is necessary to want to block the propagation path of electromagnetic waves, and the electromagnetic wave absorbing material absorbs electromagnetic waves, so as to limit the intensity of electromagnetic radiation within a safe range and reduce secondary pollution of electromagnetic waves, thereby ensuring normal operation of the device. Besides meeting the requirement of wave absorbing performance, the electromagnetic wave absorbing material is also required to have the characteristics of light weight and multifunction. The electromagnetic wave absorbing material is required to have light weight, heat insulation and sound insulation in addition to good absorbing performance. However, the wave-absorbing foam prepared in the prior art has the problem that the wave-absorbing agent is unevenly dispersed in the matrix, and is easy to cause the problem of secondary interference of electromagnetic waves, so that the wave-absorbing performance is poor.
Disclosure of Invention
The invention mainly aims to provide an electromagnetic wave absorbing foam and a preparation method thereof, which are used for solving the problem that a wave absorbing agent in the prior art is unevenly dispersed in a matrix, and the problem that the wave absorbing foam is easy to cause secondary interference of electromagnetic waves and has poor wave absorbing performance.
In order to achieve the above object, according to one aspect of the present invention, there is provided a method for preparing an electromagnetic wave absorbing foam, comprising the steps of: step S1, mixing liquid phenolic resin, a diluent and a stabilizer to form a liquid resin mixture; step S2, stirring the liquid resin mixture, and then adding pentacarbonyl iron in a stirring state to obtain a liquid precursor; and S3, pouring a liquid precursor into the mold, heating to a first temperature under inert gas to decompose iron pentacarbonyl, and then continuously heating to a second temperature to solidify the liquid phenolic resin to obtain the electromagnetic wave absorption foam.
Further, the liquid phenolic resin is a thermosetting phenolic resin, and the viscosity of the thermosetting phenolic resin is 5000-7000 cp at 25 ℃.
Further, the diluent is polypropylene glycol diglycidyl ether and/or polyethylene glycol diglycidyl ether.
Further, the stabilizer is Tween-80 and/or Tween-40.
Further, the liquid phenolic resin is 80-100 parts by weight, the diluent is 5-10 parts by weight, the stabilizer is 1-2 parts by weight, and the iron pentacarbonyl is 10-15 parts by weight.
Further, step S2 includes: placing the liquid resin mixture in a container, stirring at the speed of 300-400 r/min for 60-70 min at the temperature of 0-10 ℃, then keeping the stirring state, and adding pentacarbonyl iron into the container; after the addition, nitrogen is introduced into the container, and then the stirring state is kept for 20-30 min, so as to obtain the liquid precursor.
Further, in step S3, the inert gas is nitrogen.
Further, in step S3, the first temperature is 145-155 ℃, and the second temperature is 165-175 ℃.
Further, in the step S3, the liquid precursor is heated to a first temperature at a heating rate of 4-6 ℃/min, and is kept for 8-15 min, so that the pentacarbonyl iron is decomposed; and then continuously heating to a second temperature at a heating rate of 4-6 ℃/min, and preserving heat for 25-35 min to solidify the liquid phenolic resin, thus obtaining the electromagnetic wave absorption foam.
According to another aspect of the present invention, there is also provided an electromagnetic wave absorbing foam prepared by the above-mentioned preparation method.
The preparation method of the invention comprises the steps of firstly mixing a liquid phenolic resin matrix, a stabilizer and a diluent to form a liquid resin mixture, then adding pentacarbonyl iron into the liquid phenolic resin mixture, and then foaming and solidifying the liquid phenolic resin mixture. According to the invention, liquid phenolic resin and liquid pentacarbonyl iron are adopted for mixed foaming, so that the aggregation risk of the solid wave absorber in the resin matrix is greatly reduced, and the wave absorber is uniformly distributed in the matrix. Meanwhile, compared with the traditional process that the wave-absorbing foam is formed by mixing a resin matrix and a solid wave-absorbing agent and then adding a foaming agent for foaming, the electromagnetic wave-absorbing foam prepared by the invention does not need to add the foaming agent, but utilizes carbon monoxide gas generated by self-decomposition of pentacarbonyl iron for foaming, so that a porous structure is obtained. In addition, compared with the traditional wave-absorbing foam structure, the electromagnetic wave-absorbing foam prepared by the invention has the advantages that the iron powder generated by decomposing pentacarbonyl iron is uniformly deposited on the pore wall and the surface of the pore skeleton while foaming, and the risk of uneven foaming caused by high density of the metal wave-absorbing agent is greatly reduced.
Therefore, the invention effectively improves the dispersion uniformity of the wave absorber in the matrix, the integrally formed porous foam structure increases multiple interface reflection loss, the structure can effectively absorb electromagnetic waves, simultaneously reduces the density of shielding materials, reduces the secondary interference of the electromagnetic waves, and meets the development goal of the electromagnetic shielding materials towards high shielding efficiency and light weight. In a word, the wave-absorbing foam wave-absorbing agent prepared by the invention has uniform distribution, less electromagnetic wave secondary interference and better wave-absorbing performance.
Detailed Description
It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. The present invention will be described in detail with reference to examples.
As described in the background art, the problem of uneven dispersion of the wave absorbing agent in the matrix in the prior art is easy to cause secondary interference of electromagnetic waves in the wave absorbing foam, so that the wave absorbing performance is poor.
In order to solve the above problems, the present invention provides a method for preparing an electromagnetic wave absorbing foam, comprising the steps of: step S1, mixing liquid phenolic resin, a diluent and a stabilizer to form a liquid resin mixture; step S2, stirring the liquid resin mixture, and then adding pentacarbonyl iron in a stirring state to obtain a liquid precursor; and S3, pouring a liquid precursor into the mold, heating to a first temperature under inert gas to decompose iron pentacarbonyl, and then continuously heating to a second temperature to solidify the liquid phenolic resin to obtain the electromagnetic wave absorption foam.
The preparation method of the invention comprises the steps of firstly preparing liquid phenolic resin matrix and stabilizerMixing with diluent to form liquid resin mixture, adding pentacarbonyl iron, foaming and curing. The invention adopts liquid phenolic resin and liquid iron pentacarbonyl (light yellow liquid, density is 1.47 g/cm) 3 ) The mixing foaming is carried out, so that the agglomeration risk of the solid wave absorber in the resin matrix is greatly reduced, and the wave absorber is uniformly distributed in the matrix. Meanwhile, compared with the traditional process that the wave-absorbing foam is formed by mixing a resin matrix and a solid wave-absorbing agent and then adding a foaming agent for foaming, the electromagnetic wave-absorbing foam prepared by the invention does not need to add the foaming agent, but utilizes carbon monoxide gas generated by self-decomposition of pentacarbonyl iron for foaming, so that a porous structure is obtained. In addition, compared with the traditional wave-absorbing foam structure, the electromagnetic wave-absorbing foam prepared by the invention has the advantages that the iron powder generated by decomposing pentacarbonyl iron is uniformly deposited on the pore wall and the surface of the pore skeleton while foaming, and the risk of uneven foaming caused by high density of the metal wave-absorbing agent is greatly reduced.
Therefore, the invention effectively improves the dispersion uniformity of the wave absorber in the matrix, the integrally formed porous foam structure increases multiple interface reflection loss, the structure can effectively absorb electromagnetic waves, simultaneously reduces the density of shielding materials, reduces the secondary interference of the electromagnetic waves, and meets the development goal of the electromagnetic shielding materials towards high shielding efficiency and light weight. In a word, the wave-absorbing foam wave-absorbing agent prepared by the invention has uniform distribution, less electromagnetic wave secondary interference and better wave-absorbing performance.
In a preferred embodiment, the liquid phenolic resin is a thermosetting phenolic resin having a viscosity of 5000 to 7000cp at 25 ℃. The thermosetting liquid phenolic resin with the viscosity can form better fusion with other components, the dispersion of pentacarbonyl iron in the thermosetting liquid phenolic resin is more uniform, the foaming effect is better, the cell structure is more complete, the size is more suitable, and the formed thin foam has better wave absorbing effect.
To further perform the dilution, in a preferred embodiment, the above-described diluents include, but are not limited to, polypropylene glycol diglycidyl ether and/or polyethylene glycol diglycidyl ether. The diluent can further reduce the viscosity of the liquid precursor, so that the foaming effect is better, and meanwhile, better fusion with other components can be formed, and particularly, the diluent has better promotion effect on the dispersion of iron pentacarbonyl.
Preferably, the stabilizer is tween-80 and/or tween-40. The use of the above type of stabilizer helps to further improve the stability of the foaming process, promoting a wave-absorbing foam with a more uniform cell structure.
For the purpose of further exerting the effects of the components so as to further improve the foaming effect and the foam wave absorbing effect, in a preferred embodiment, the liquid phenolic resin is 80-100 parts by weight, the diluent is 5-10 parts by weight, the stabilizer is 1-2 parts by weight, and the pentacarbonyl iron is 10-15 parts by weight.
In order to make the foaming process more stable and the components more dispersed, in a preferred embodiment, step S2 described above comprises: placing the liquid resin mixture in a container, stirring at a speed of 300-400 r/min under the condition of 0-10 ℃ (such as ice water bath) for 60-70 min, then keeping a stirring state, and adding pentacarbonyl iron into the stirring state; after the addition, nitrogen is introduced into the container, and then the stirring state is kept for 20-30 min, so as to obtain the liquid precursor.
The purpose of the inert gas is to isolate air, and a specific type may be nitrogen. In a preferred embodiment, in the step S3, the first temperature is 145 to 155 ℃ and the second temperature is 165 to 175 ℃.
In a preferred embodiment, in step S3, the liquid precursor is heated to a first temperature at a heating rate of 4-6 ℃/min and is kept for 8-15 min to decompose iron pentacarbonyl; and then continuously heating to a second temperature at a heating rate of 4-6 ℃/min, and preserving heat for 25-35 min to solidify the liquid phenolic resin, thus obtaining the electromagnetic wave absorption foam.
According to another aspect of the present invention, there is also provided an electromagnetic wave absorbing foam prepared by the above-mentioned preparation method. The invention effectively improves the dispersion uniformity of the wave absorber in the matrix, the integrally formed porous foam structure increases multiple interface reflection loss, the structure can effectively absorb electromagnetic waves, simultaneously reduces the density of shielding materials, reduces the secondary interference of the electromagnetic waves, and meets the development aim of the electromagnetic shielding materials towards high shielding efficiency and light weight. In a word, the wave-absorbing foam wave-absorbing agent prepared by the invention has uniform distribution, less electromagnetic wave secondary interference and better wave-absorbing performance.
The present application is described in further detail below in conjunction with specific embodiments, which should not be construed as limiting the scope of the claims.
Example 1:
according to parts by weight, 100 parts of liquid phenolic resin, 5 parts of polyethylene glycol diglycidyl ether and 1 part of tween-80 are uniformly mixed and then added into a three-neck flask, stirring is carried out for 70min at the speed of 300r/min under the condition of ice water bath (0-10 ℃), then 15 parts of liquid pentacarbonyl iron is slowly added under the stirring state, then nitrogen is introduced to exhaust the air in the flask, and stirring is continued for 30min in the nitrogen atmosphere, so as to obtain the liquid precursor.
Pouring the liquid precursor into a mold coated with a release agent and having the dimensions of 300mm multiplied by 2mm, covering a cover, rapidly placing into an atmosphere furnace, introducing nitrogen gas to exhaust air in the furnace, heating the atmosphere furnace to 150 ℃ at the speed of 5 ℃/min, preserving heat for 10min, heating to 170 ℃ at the speed of 5 ℃/min, preserving heat for 30min, introducing nitrogen gas to naturally cool the atmosphere furnace to room temperature, and finally taking out the mold for demolding to obtain the electromagnetic wave absorption foam.
Example 2:
example 2 differs from example 1 in that the stabilizer species was changed:
according to parts by weight, 100 parts of liquid phenolic resin, 5 parts of polyethylene glycol diglycidyl ether and 1 part of tween-40 are uniformly mixed and then added into a three-neck flask, stirring is carried out for 70min at the speed of 300r/min under the condition of ice water bath (0-10 ℃), then 15 parts of liquid pentacarbonyl iron is slowly added under the stirring state, then nitrogen is introduced to exhaust the air in the flask, and stirring is continued for 30min in the nitrogen atmosphere, so as to obtain the liquid precursor.
Pouring the liquid precursor into a mold coated with a release agent and having the dimensions of 300mm multiplied by 2mm, covering a cover, rapidly placing into an atmosphere furnace, introducing nitrogen gas to exhaust air in the furnace, heating the atmosphere furnace to 150 ℃ at the speed of 5 ℃/min, preserving heat for 10min, heating to 170 ℃ at the speed of 5 ℃/min, preserving heat for 30min, introducing nitrogen gas to naturally cool the atmosphere furnace to room temperature, and finally taking out the mold for demolding to obtain the electromagnetic wave absorption foam.
Example 3:
example 3 differs from example 1 in that the amount of stabilizer added was changed:
according to parts by weight, 100 parts of liquid phenolic resin, 5 parts of polyethylene glycol diglycidyl ether and 1.5 parts of tween-80 are uniformly mixed and then added into a three-neck flask, stirring is carried out for 70min at the speed of 300r/min under the condition of ice water bath (0-10 ℃), then 15 parts of liquid pentacarbonyl iron is slowly added under the stirring state, then nitrogen is introduced to exhaust the air in the flask, and stirring is continued for 30min in the nitrogen atmosphere, so as to obtain the liquid precursor.
Pouring the liquid precursor into a mold coated with a release agent and having the dimensions of 300mm multiplied by 2mm, covering a cover, rapidly placing into an atmosphere furnace, introducing nitrogen gas to exhaust air in the furnace, heating the atmosphere furnace to 150 ℃ at the speed of 5 ℃/min, preserving heat for 10min, heating to 170 ℃ at the speed of 5 ℃/min, preserving heat for 30min, introducing nitrogen gas to naturally cool the atmosphere furnace to room temperature, and finally taking out the mold for demolding to obtain the electromagnetic wave absorption foam.
Example 4:
example 4 differs from example 1 in that two stabilizers are used:
according to parts by weight, 100 parts of liquid phenolic resin, 5 parts of polyethylene glycol diglycidyl ether, 0.5 part of tween-80 and 0.5 part of tween-40 are uniformly mixed and then added into a three-neck flask, stirring is carried out for 70min at the speed of 300r/min under the condition of ice water bath (0-10 ℃), then 15 parts of liquid pentacarbonyl iron is slowly added under the stirring state, then nitrogen is introduced to exhaust the air in the flask, and stirring is continued for 30min in the nitrogen atmosphere, so as to obtain a liquid precursor.
Pouring the liquid precursor into a mold coated with a release agent and having the dimensions of 300mm multiplied by 2mm, covering a cover, rapidly placing into an atmosphere furnace, introducing nitrogen gas to exhaust air in the furnace, heating the atmosphere furnace to 150 ℃ at the speed of 5 ℃/min, preserving heat for 10min, heating to 170 ℃ at the speed of 5 ℃/min, preserving heat for 30min, introducing nitrogen gas to naturally cool the atmosphere furnace to room temperature, and finally taking out the mold for demolding to obtain the electromagnetic wave absorption foam.
Example 5:
example 5 differs from example 1 in the parts of liquid phenolic resin, polyethylene glycol diglycidyl ether, liquid iron pentacarbonyl and part of the process conditions are changed:
according to parts by weight, 80 parts of liquid phenolic resin, 10 parts of polyethylene glycol diglycidyl ether and 2 parts of tween-80 are uniformly mixed and then added into a three-neck flask, stirring is carried out for 60min at the speed of 400r/min under the condition of ice water bath (0-10 ℃), then 10 parts of liquid pentacarbonyl iron is slowly added under the stirring state, then nitrogen is introduced to exhaust the air in the flask, and stirring is continued for 20min in the nitrogen atmosphere, so as to obtain the liquid precursor.
Pouring the liquid precursor into a mold coated with a release agent and having the dimensions of 300mm multiplied by 2mm, covering a cover, rapidly placing into an atmosphere furnace, introducing nitrogen gas to exhaust air in the furnace, heating the atmosphere furnace to 145 ℃ at the speed of 6 ℃/min, preserving heat for 15min, heating to 175 ℃ at the speed of 6 ℃/min, preserving heat for 25min, introducing nitrogen gas to naturally cool the atmosphere furnace to room temperature, and finally taking out the mold for demolding to obtain the electromagnetic wave absorption foam.
Comparative example 1
According to parts by weight, 100 parts of liquid phenolic resin, 10 parts of polyethylene glycol diglycidyl ether and 2 parts of tween-80 are uniformly mixed, added into a beaker, stirred at the speed of 400r/min for 10min, then 10 parts of carbonyl iron powder is slowly added in a stirred state, stirring is continued for 20min, and then a foaming agent n-pentane and a curing agent terephthalic acid are added, and stirring is carried out for 1-2min to obtain a liquid precursor.
Pouring the liquid precursor into a mold coated with a release agent and having the dimensions of 300mm multiplied by 2mm, covering a cover, placing into an oven, then placing into the oven at 70 ℃ for heat preservation for 50-60min for foaming, naturally cooling to room temperature, and finally taking out the mold for demolding to obtain the electromagnetic wave absorption foam.
The materials prepared in the examples were taken separately and tested for-10 dB bandwidth, density and compressive strength, and the test results are shown in table 1:
TABLE 1
The dispersion uniformity of the wave absorber in the matrix is improved, the-10 dB bandwidth is relatively wider, and the absorption effect is better; compared with the traditional solid wave absorber which has high density and poor foamability after being mixed with a matrix, the liquid pentacarbonyl iron provided by the invention is relatively uniform in distribution after being mixed with the matrix and foamed, the foaming multiplying power is improved, and the density and the compression strength of foam are relatively slightly reduced, so that the dispersion of the wave absorber in the matrix can be judged from the above indexes, the electromagnetic wave secondary interference is less, and the wave absorber has better wave absorbing performance.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A method for preparing an electromagnetic wave absorbing foam, comprising the steps of:
step S1, mixing liquid phenolic resin, a diluent and a stabilizer to form a liquid resin mixture;
step S2, stirring the liquid resin mixture, and then adding pentacarbonyl iron in a stirring state to obtain a liquid precursor;
and S3, pouring the liquid precursor into a mould, heating to a first temperature under inert gas to decompose the iron pentacarbonyl, and then continuously heating to a second temperature to cure the liquid phenolic resin to obtain the electromagnetic wave absorption foam.
2. The method of claim 1, wherein the liquid phenolic resin is a thermosetting phenolic resin having a viscosity of 5000 to 7000cp at 25 ℃.
3. The preparation method according to claim 1, wherein the diluent is polypropylene glycol diglycidyl ether and/or polyethylene glycol diglycidyl ether.
4. The method of claim 1, wherein the stabilizer is tween-80 and/or tween-40.
5. The production method according to any one of claims 1 to 4, wherein the liquid phenolic resin is 80 to 100 parts by weight, the diluent is 5 to 10 parts by weight, the stabilizer is 1 to 2 parts by weight, and the iron pentacarbonyl is 10 to 15 parts by weight.
6. The method according to any one of claims 1 to 4, wherein the step S2 comprises:
placing the liquid resin mixture in a container, stirring at a speed of 300-400 r/min for 60-70 min at a temperature of 0-10 ℃, then keeping a stirring state, and adding the pentacarbonyl iron into the container;
after the addition, nitrogen is introduced into the container, and then the stirring state is kept for 20-30 min, so as to obtain the liquid precursor.
7. The method according to any one of claims 1 to 4, wherein in the step S3, the inert gas is nitrogen.
8. The method according to any one of claims 1 to 4, wherein in the step S3, the first temperature is 145 to 155 ℃ and the second temperature is 165 to 175 ℃.
9. The method according to claim 8, wherein in the step S3, the liquid precursor is heated to the first temperature at a heating rate of 4 to 6 ℃/min, and is kept for 8 to 15min, so that the iron pentacarbonyl is decomposed; and then continuously heating to the second temperature at a heating rate of 4-6 ℃/min, and preserving heat for 25-35 min to solidify the liquid phenolic resin, thereby obtaining the electromagnetic wave absorption foam.
10. An electromagnetic wave absorbing foam, characterized by being produced by the production method according to any one of claims 1 to 9.
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| CN202111511981.2A CN116218132A (en) | 2021-12-06 | 2021-12-06 | Electromagnetic wave absorbing foam and preparation method thereof |
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| CN202111511981.2A CN116218132A (en) | 2021-12-06 | 2021-12-06 | Electromagnetic wave absorbing foam and preparation method thereof |
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