CN114874594B

CN114874594B - High-resilience wave-absorbing foam material and preparation method thereof

Info

Publication number: CN114874594B
Application number: CN202210563715.2A
Authority: CN
Inventors: 孙浩杰; 崔丽云; 王奇; 杨熙; 舒孟鑫; 吴清华; 贾俊雪; 吴文雷
Original assignee: Chambroad Chemical Industry Research Institute Co Ltd
Current assignee: Chambroad Chemical Industry Research Institute Co Ltd
Priority date: 2022-05-23
Filing date: 2022-05-23
Publication date: 2023-08-01
Anticipated expiration: 2042-05-23
Also published as: CN114874594A

Abstract

The invention provides a high-resilience wave-absorbing foaming material which is prepared from the following components in parts by weight: 20-95 parts of PBAT resin; 5-80 parts of thermoplastic elastomer; 0.5-10 parts of bridging agent; 0.2 to 3 parts of hydrolysis resistance agent; 0.1-2 parts of cell regulator; 2-20 parts of wave-absorbing auxiliary agent; the bridging agent is one or more of ethylene-methyl methacrylate copolymer, nitrile rubber, vinyl triethoxysilane and styrene-glycidyl methacrylate copolymer. The high-resilience wave-absorbing foam material provided by the invention has the excellent performances of degradability, high resilience and wave absorption. The invention also provides a preparation method of the high-resilience wave-absorbing foaming material.

Description

High-resilience wave-absorbing foam material and preparation method thereof

Technical Field

The invention belongs to the technical field of foaming materials, and particularly relates to a high-resilience wave-absorbing foaming material and a preparation method thereof.

Background

The foam plastic has the excellent performances of light weight, heat insulation, sound absorption, shock absorption, buffering, energy storage and the like, and is widely applied to the fields of packaging materials, vehicles, building decorations, sports and leisure, catering logistics and the like. At present, the more common foamed plastics are polystyrene, polyethylene, polyvinyl chloride, polyurethane and the like, but the foamed materials are non-elastomers, have poor performance in rebound resilience, have rebound resilience of generally lower than 30 percent, cause certain pollution and harm to the environment, and have certain short plates in functional application.

The foam plastic has high requirements on the fields of communication equipment, network terminals, digital home appliances, microwave appliances, electronic products, aerospace and the like, and the foam plastic has the advantages of light weight, energy storage performance, absorption and elimination of electromagnetic wave pollution harmful to human bodies and the environment, such as design and protection of network machine rooms, CT ward equipment of hospitals and doors and windows.

Disclosure of Invention

The invention aims to provide a high-resilience wave-absorbing foam material and a preparation method thereof.

The invention provides a high-resilience wave-absorbing foaming material which is prepared from the following components in parts by weight:

the bridging agent is one or more of ethylene-methyl methacrylate copolymer, nitrile rubber, vinyl triethoxysilane and styrene-glycidyl methacrylate copolymer.

Preferably, the thermoplastic elastomer is one or more of styrene elastomer, polyolefin elastomer, polyurethane elastomer, polyamide elastomer, polyester elastomer, vulcanized rubber and ethylene-vinyl acetate copolymer.

Preferably, the anti-hydrolysis agent is one or more of carbodiimide and polycarbodiimide;

the foam pore regulator is one or more of calcium carbonate, talcum powder, kaolin, montmorillonite, diatomite, silica micropowder, white carbon black and mica powder;

the wave-absorbing auxiliary agent is one or more of carbon fiber, carbon black, graphene, carbon nano tube, silicon carbide, polyaniline and poly-p-phenylacetylene.

The invention provides a preparation method of the rebound wave-absorbing foaming material, which comprises the following steps:

a) Mixing the PBAT resin with a thermoplastic elastomer, a bridging agent, an anti-hydrolysis agent, a cell regulator and a wave absorbing auxiliary agent, and then sequentially carrying out melting, extrusion, calendaring and shaping to obtain a plate blank;

b) Placing the slab into a die cavity, and performing supercritical foaming to obtain a primary foaming material;

c) And (3) carrying out hot press shaping on the primary foaming material to obtain the high-resilience wave-absorbing foaming material.

Preferably, in the step A), an extruder is used for extrusion, and the temperature of the extruder is 120-220 ℃; the rotating speed of the extruder is 80-300 r/min.

Preferably, the step B) uses supercritical gas for supercritical foaming, wherein the supercritical gas is carbon dioxide or a mixture of carbon dioxide and nitrogen.

Preferably, the temperature of the supercritical foaming is 70-120 ℃, the pressure of the supercritical foaming is 6-20 MPa, and the heat preservation and pressure maintaining time of the supercritical foaming is 0.5-3 hours.

Preferably, the pressure release rate of the supercritical foaming is 1-20 MPa/s.

Preferably, the temperature of the hot press shaping is 50-100 ℃, the pressure of the hot press shaping is 0.1-5 MPa, and the time of the hot press shaping is 1-10 min.

The invention provides a high-resilience wave-absorbing foaming material which is prepared from the following components in parts by weight: 20-95 parts of PBAT resin; 5-80 parts of thermoplastic elastomer; 0.5-10 parts of bridging agent; 0.2 to 3 parts of hydrolysis resistance agent; 0.1-2 parts of cell regulator; 2-20 parts of wave-absorbing auxiliary agent; the bridging agent is one or more of ethylene-methyl methacrylate copolymer, nitrile rubber, vinyl triethoxysilane and styrene-glycidyl methacrylate copolymer.

Compared with the prior art, the invention has the following beneficial effects:

1. according to the invention, the bridging agent is adopted to organically combine the PBAT resin and the thermoplastic elastomer through the functional group chemical reaction at the end part of the molecular chain, so that the length and the branching degree of the molecular chain are increased, the supercritical gas foaming process is controllable, the regular hexagon with uniform foam pore structure and regular foam pore shape can be prepared, meanwhile, the PBAT resin and the thermoplastic elastomer endow the foaming material with better toughness, high rebound property is realized, the rebound rate can reach more than 60%, and the rebound rate of other non-elastomer foaming materials is generally lower than 30%.

2. The PBAT resin is a biodegradable material, and after the product reaches the service life, the PBAT resin can be degraded under the action of natural environment and microorganisms, and free radicals generated by the breakage of PBAT molecular chains can induce the thermoplastic elastomer combined with the PBAT molecular chains to be decomposed and degraded, so that compared with other non-degradable foaming materials, the PBAT resin has less influence on environment and ecology.

3. The foam regulator adopted by the invention not only can play a role in heterogeneous nucleation in the foaming process, but also can regulate the foam structure, so that the foaming material has smaller foam diameter and more than 95% of foam integrity.

4. According to the invention, the wave-absorbing auxiliary agent is added into the material, and in the supercritical fluid foaming process, the internal friction force generated by the motion of the wave-absorbing auxiliary agent and the polymer chain segment maintains the relative stability of the viscosity of the PBAT resin, so that the uniformity and stability of the foaming material are improved, the function of absorbing electromagnetic waves is realized in advance of light weight, and the method has a certain significance for places with great electromagnetic radiation hazard and special application occasions.

5. The invention adopts one-step molding foaming in the foaming mode, has simple process and strong operability, adopts inert gases such as carbon dioxide or nitrogen and the like, is environment-friendly and clean, is natural and harmless, and has high safety.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.

FIG. 1 is a scanning electron microscope image of the high resilience wave-absorbing foam material prepared in example 1 of the present invention.

Detailed Description

In the invention, the PBAT resin is a copolymer of butanediol adipate and butanediol terephthalate; the PBAT is preferably 20 to 95 parts by weight, preferably 30 to 90 parts by weight, such as 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, 90 parts, 95 parts, preferably a range having any of the above values as an upper limit or a lower limit.

In the present invention, the thermoplastic elastomer is one or more of styrene elastomer (TPS), polyolefin elastomer (TPO), polyurethane elastomer (TPU), polyamide elastomer (TPEE), polyester elastomer (TPEE), vulcanized rubber (TPV), ethylene-vinyl acetate copolymer (EVA); the thermoplastic elastomer is preferably 5 to 80 parts by weight, more preferably 10 to 70 parts by weight, for example, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, and a range value in which any of the above values is an upper limit or a lower limit is preferable.

The PBAT resin is a block polymer formed by copolymerization of aliphatic and aromatic, can be degraded in a biological environment, and is a typical thermoplastic elastomer, wherein the aliphatic chain segment in the PBAT resin has good flexibility and endows the material with good toughness, unlike other degradable materials. In order to further improve the comprehensive performance of the PBAT resin, particularly to improve the rebound resilience of the foaming material, the composition is blended with other thermoplastic elastomers and well combined together through chemical action.

In the invention, the bridging agent is preferably one or more of ethylene-methyl methacrylate copolymer, nitrile rubber, vinyl triethoxysilane and styrene-glycidyl methacrylate copolymer; the weight part of the bridging agent is preferably 0.5 to 10 parts, more preferably 1 to 9 parts, such as 0.5 part, 1 part, 1.5 part, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, preferably a range having any of the above values as an upper limit or a lower limit.

The peroxide bridging agent is mainly suitable for chemical foaming, and has large gas quantity and high corresponding crosslinking degree in the chemical foaming process. In the supercritical fluid physical foaming process, the polymer is required to have a wide molecular weight distribution and a multi-branched structure, the cross-linking process is controllable, ethylene-methyl methacrylate copolymer, nitrile rubber, vinyl triethoxysilane, styrene-glycidyl methacrylate copolymer and the like have epoxy groups or vinyl functional groups and are distributed at the end parts of molecular chains, and the ethylene-methyl methacrylate copolymer and the nitrile rubber can be subjected to a branching reaction of the molecular chains with PBAT molecules, and simultaneously are entangled with other thermoplastic elastomers through chemical reaction, so that the viscoelasticity of the polymer material is improved, and the foamable temperature interval of the PBAT resin is increased.

In the invention, the anti-hydrolysis agent is one or more of carbodiimide and polycarbodiimide; the weight part of the anti-hydrolysis agent is preferably 0.2 to 3 parts, more preferably 0.5 to 2.5 parts, such as 0.2 parts, 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, preferably a range having any of the above values as an upper limit or a lower limit.

The cell regulator is preferably one or more of calcium carbonate, talcum powder, kaolin, montmorillonite, diatomite, silica micropowder, white carbon black and mica powder; the weight part of the cell regulator is preferably 0.1 to 2 parts, such as 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1 part, 1.1 part, 1.2 part, 1.3 part, 1.4 part, 1.5 part, 1.6 part, 1.7 part, 1.8 part, 1.9 part, 2 parts, preferably a range value in which any of the above values is the upper limit or the lower limit.

In the present invention, the cell regulator is preferably treated with one or more of fatty acid, aromatic acid, coupling agent and surfactant, and the activity is more than 90%, preferably powder with D97 particle size less than 10 μm. The treatment method is a conventional method in the industry, and is not described in detail herein.

The foam cell nucleating agent plays a role in heterogeneous nucleation in the foaming process, powder with the D97 particle size smaller than 10 mu m has smaller size, the density of the foam cells is increased, the size of the foam cells is reduced, the size of the foam cells is smaller than 80 mu m, the foam cell regulator is subjected to organic treatment, the activation degree is larger than 90%, the dispersion performance of the foam cell nucleating agent and the matrix resin is good, meanwhile, the surface organic matters can regulate the surface tension of the foam cells, the breaking rate of the foam cells is reduced, and the complete foam cell structure is kept above 95%.

In the invention, the wave-absorbing auxiliary agent is preferably one or more of carbon fiber, carbon black, graphene, carbon nano tube, silicon carbide, polyaniline and poly-p-phenylacetylene; the weight part of the wave-absorbing auxiliary agent is preferably 2 to 20 parts, more preferably 5 to 15 parts, such as 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, and preferably a range value in which any of the above values is an upper limit or a lower limit.

The wave-absorbing auxiliary agent not only endows the material with special performance in the high molecular foaming material, but also can not negatively influence the foaming process. Different from the traditional foaming mode, in the supercritical fluid foaming process, the plasticizing effect of high-pressure gas enables the fluidity of the polymer material to be increased in the foaming process, the viscosity to be reduced, and carbon fiber, carbon black, graphene, carbon nano tube, silicon carbide, polyaniline, poly-p-phenylacetylene and other micro-particles move along with the peristaltic motion of a molecular chain segment, and the internal friction force between the micro-particles maintains the relative stability of the viscosity of the PBAT resin, so that the uniformity and the quality stability of the PBAT foaming material are improved.

The invention also provides a preparation method of the rebound wave-absorbing foaming material, which comprises the following steps:

In the present invention, the types and amounts of the PBAT resin, the thermoplastic elastomer, the bridging agent, the hydrolysis inhibitor, the cell regulator and the wave absorbing auxiliary agent are the same as those of the PBAT resin, the thermoplastic elastomer, the bridging agent, the hydrolysis inhibitor, the cell regulator and the wave absorbing auxiliary agent described above, and the present invention is not repeated here.

The invention mixes the above raw materials in a high-speed mixer uniformly, melts the materials in an extruder, forms the melted materials into plate blanks in a slit machine head, and then calendars the plate blanks by a three-roller tabletting machine, cools and shapes the plate blanks, and cuts the plate blanks into required plate sizes.

In the present invention, the melting temperature is preferably 140 to 180 ℃, more preferably 150 to 170 ℃, such as 140 ℃,150 ℃, 160 ℃, 170 ℃, 180 ℃, and preferably ranges from any of the above values to the upper or lower limit.

The temperature of each section of the extruder is 120-220 ℃, specifically, the extrusion fraction is 9 temperature areas, 1 area 120-130 ℃,2 area 140-160 ℃,3 area 200-210 ℃,4 area 200-210 ℃,5 area 210-220 ℃,6 area 210-220 ℃,7 area 210-220 ℃,8 area 200-210 ℃ and 9 area 180-200 ℃.

The rotation speed of the extruder is preferably 8-300 r/min, more preferably 50-250 r/min, such as 8r/min,10r/min,50r/min,100r/min,150r/min,200r/min,250r/min,300r/min, preferably a range value with any of the above values as an upper limit or a lower limit.

In the present invention, the thickness of the sheet is preferably > 1mm.

The obtained plate is placed in a die cavity, supercritical gas is introduced to perform supercritical foaming, and then the pressure in the die cavity is quickly released, so that the primary foaming material is obtained. The present invention preferably performs supercritical foaming in a compression foaming apparatus having an oil bath heating system.

In the present invention, the supercritical gas is preferably carbon dioxide or a mixed gas of carbon dioxide and nitrogen, and the supercritical foaming temperature is preferably 70 to 120 ℃, more preferably 80 to 110 ℃, such as 70 ℃, 80 ℃, 90 ℃,100 ℃, 110 ℃, 120 ℃, preferably a range value in which any of the above values is an upper limit or a lower limit; the pressure of the supercritical foaming is preferably 6 to 20MPa, more preferably 10 to 15MPa, such as 6MPa, 7MPa, 8MPa, 9MPa, 10MPa, 11MPa, 123MPa, 13MPa, 14MPa, 15MPa, 16MPa, 17MPa, 18MPa, 19MPa, 20MPa, and preferably a range having any of the above values as an upper limit or a lower limit; the holding time for the supercritical foaming is preferably 0,5 to 3 hours, more preferably 1 to 2.5 hours, such as 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, and preferably a range having any of the above values as an upper limit or a lower limit.

In the present invention, the pressure release rate of the supercritical foaming is preferably 1 to 20Mpa/s, more preferably 5 to 15Mpa/s, such as 1Mpa/s,2Mpa/s,3Mpa/s,4Mpa/s,5Mpa/s,6Mpa/s,7Mpa/s,8Mpa/s,9Mpa/s,10Mpa/s,11Mpa/s,12Mpa/s,13Mpa/s,14Mpa/s,15Mpa/s,16Mpa/s,17Mpa/s,18Mpa/s,19Mpa/s,20Mpa/s, preferably a range value having any of the above values as an upper limit or a lower limit.

After the foaming material is obtained, the primary foaming material is subjected to hot press shaping in a flat vulcanizing machine to obtain the rebound wave-absorbing foaming material.

In the present invention, the temperature of the heat press molding is preferably 50 to 100 ℃, more preferably 60 to 90 ℃, such as 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃, 95 ℃,100 ℃, preferably a range value in which any of the above values is the upper limit or the lower limit; the pressure of the hot press forming is 0.1 to 5MPa, more preferably 1 to 4MPa, such as 0.1MPa,0.5MPa,1MPa,1.5MPa,2MPa,2.5MPa,3MPa,3.5MPa,4MPa,4.5MPa,5MPa, and preferably a range having any of the above values as an upper limit or a lower limit. The time for the heat press setting is preferably 1 to 10min, more preferably 3 to 8min, such as 1min, 2min, 3min, 4min, 5min, 6min, 7min, 8min, 9min, 10min, preferably a range value having any of the above values as an upper limit or a lower limit.

In order to further illustrate the present invention, the following examples are provided to describe a high resilience wave-absorbing foam material and a preparation method thereof in detail, but the present invention is not to be construed as being limited to the scope of protection.

Example 1

(1) Uniformly mixing 40 parts of PBAT resin, 60 parts of ethylene-vinyl acetate copolymer, 1 part of nitrile rubber, 0.5 part of polycarbodiimide, 0.2 part of light calcium carbonate and 5 parts of carbon fiber in a high-speed mixer, melting the materials in an extruder at 160 ℃ at 120r/min, forming the melted materials into plate blanks in a slit machine head, calendaring by a three-roller sheeter, cooling and shaping, and cutting into plates with the thickness of 4 mm.

(2) Starting an oil bath heating system of the compression molding foaming equipment, heating to 80 ℃, opening a die cavity, putting the formed plate cut in the step S1 into the die cavity, closing the die cavity, pumping supercritical carbon dioxide gas into the die cavity through a booster pump to ensure that the pressure in the die cavity is 20MPa, preserving heat and maintaining pressure for 1h, then rapidly releasing the pressure in the die cavity, and ensuring that the pressure release rate is 10MPa/S, thereby obtaining the primary foaming material.

(3) And (2) rapidly transferring the primary foaming material obtained in the step (S2) to a flat vulcanizing machine for hot pressing and shaping for 1min, wherein the temperature of the flat vulcanizing machine is 80 ℃, the pressure is 1MPa, and the high-resilience wave-absorbing foaming material finished product is obtained after shaping.

Example 2

(1) Uniformly mixing 60 parts of PBAT resin, 40 parts of polyurethane elastomer, 0.5 part of ethylene-methyl methacrylate copolymer, 0.2 part of carbodiimide, 0.5 part of white carbon black and 10 parts of polyaniline in a high-speed mixer, melting the materials in an extruder at the melting temperature of 140 ℃ at the rotating speed of 150r/min, forming the melted materials into plate blanks in a slit machine head, calendaring by a three-roller tabletting machine, cooling and shaping, and cutting into plates with the thickness of 3 mm.

(2) Starting an oil bath heating system of the mould pressing foaming equipment, heating to 90 ℃, opening a mould cavity, putting the formed plate cut in the step S1 into the mould cavity, closing the mould cavity, pumping supercritical carbon dioxide and supercritical nitrogen into the mould cavity by a booster pump in sequence, keeping the pressure in the mould cavity at 15MPa, preserving heat and maintaining the pressure for 1.5 hours, then rapidly releasing the pressure in the mould cavity, and releasing the pressure at the pressure release rate of 5MPa/S to obtain the primary foaming material.

(3) And (2) rapidly transferring the primary foaming material obtained in the step (S2) to a flat vulcanizing machine for hot pressing and shaping for 2min, wherein the temperature of the flat vulcanizing machine is 85 ℃, the pressure is 0.5MPa, and the high-resilience wave-absorbing foaming material finished product is obtained after shaping.

Example 3

(1) Uniformly mixing 80 parts of PBAT resin, 20 parts of ethylene-vinyl acetate copolymer, 0.8 part of vinyl triethoxysilane, 0.8 part of polycarbodiimide, 0.65 part of kaolin and 3 parts of carbon nano tubes in a high-speed mixer, melting the materials in an extruder at 180 ℃ at the speed of 200r/min, forming the melted materials into plate blanks in a slit machine head, calendaring by a three-roller tablet press, cooling and shaping, and cutting into plates with the thickness of 10 mm.

(2) Starting an oil bath heating system of the compression molding foaming equipment, heating to 110 ℃, opening a die cavity, putting the formed plate cut in the step S1 into the die cavity, closing the die cavity, pumping supercritical carbon dioxide gas into the die cavity through a booster pump to enable the pressure in the die cavity to be 10MPa, preserving heat and pressure for 3 hours, then rapidly releasing the pressure in the die cavity and enabling the pressure release rate to be 10MPa/S, thus obtaining the primary foaming material.

(3) And (2) rapidly transferring the primary foaming material obtained in the step (S2) to a flat vulcanizing machine for hot pressing and shaping for 5min, wherein the temperature of the flat vulcanizing machine is 90 ℃, the pressure is 2MPa, and the high-resilience wave-absorbing foaming material finished product is obtained after shaping.

Example 4

(1) Uniformly mixing 20 parts of PBAT resin, 80 parts of styrene elastomer, 3 parts of styrene-glycidyl methacrylate, 1 part of carbodiimide, 1 part of talcum powder and 15 parts of poly-p-phenylene vinylene in a high-speed mixer, melting the materials in an extruder at a melting temperature of 150 ℃ and a rotating speed of 160r/min, forming the melted materials into plate blanks in a slit machine head, calendaring by a three-roller tabletting machine, cooling and shaping, and cutting into plates with a thickness of 6 mm.

(2) Starting an oil bath heating system of the compression molding foaming equipment, heating to 120 ℃, opening a die cavity, putting the formed plate cut in the step S1 into the die cavity, closing the die cavity, pumping supercritical carbon dioxide and supercritical nitrogen into the die cavity by a booster pump in sequence, keeping the pressure in the die cavity at 12MPa, preserving heat and maintaining the pressure for 2 hours, then rapidly releasing the pressure in the die cavity, and releasing the pressure at the pressure rate of 12MPa/S to obtain the primary foaming material.

(3) And (2) rapidly transferring the primary foaming material obtained in the step (S2) to a flat vulcanizing machine for hot pressing for 10min for shaping, wherein the temperature of the flat vulcanizing machine is 60 ℃, the pressure is 2MPa, and the high-resilience wave-absorbing foaming material finished product is obtained after shaping.

Comparative example 1

(1) Uniformly mixing 40 parts of PBAT resin, 60 parts of ethylene-vinyl acetate copolymer, 1 part of nitrile rubber, 0.5 part of polycarbodiimide and 0.2 part of light calcium carbonate in a high-speed mixer, melting the materials in an extruder at 160 ℃ at 120r/min, forming the melted materials into plate blanks in a slit machine head, calendaring by a three-roller tabletting machine, cooling for shaping, and cutting into plates with the thickness of 4 mm.

Comparative example 1 compared with example 1, the carbon fiber without wave-absorbing auxiliary agent was added, and the composition of other material formulas and the technological parameters of the preparation process were consistent.

Comparative example 2

Placing a polystyrene board in a mold cavity of a mold pressing foaming device, heating to 125 ℃, pumping supercritical carbon dioxide gas into the mold cavity through a booster pump to ensure that the pressure in the mold cavity is 20MPa, preserving heat and pressure for 1h, then rapidly releasing the pressure in the mold cavity, and ensuring that the pressure release rate is 10MPa/s, and obtaining the polystyrene foaming material after hot pressing and shaping of a press vulcanizer.

Comparative example 3

And (3) placing the polypropylene plate in a mold cavity of a mold pressing foaming device, heating to 135 ℃, pumping supercritical carbon dioxide gas into the mold cavity through a booster pump to ensure that the pressure in the mold cavity is 15MPa, preserving heat and pressure for 1h, then rapidly releasing the pressure in the mold cavity, and performing hot pressing shaping on the polypropylene plate at the pressure release rate of 12MPa/s to obtain the polypropylene foaming material.

The dielectric loss tangent is an important parameter for representing the wave absorbing performance of the material, and the absorption effect on electromagnetic waves is weak when the dielectric loss tangent is smaller than 0.1, and the absorption effect on electromagnetic waves is better when the dielectric loss tangent is larger than 0.5.

The foaming materials prepared in examples and comparative examples were subjected to performance test, and the test results are shown in table 1 below.

Table 1 test data for the properties of the foaming materials prepared in examples and comparative examples

	Density (Kg/m) ³ )	Cell size (μm)	Rebound Rate (%)	Dielectric loss tangent value
					Test standard	GB/T 6343-2009	QB/T 5490-2020	GB/T 6670-2008	GB/T 5593-2015
Example 1	86	34	62	0.75
					Example 2	72	48	63	0.74
Example 3	90	31	61	0.67
					Example 4	69	50	68	0.61
Comparative example 1	84	46	62	0.05
					Comparative example 2	74	80	24	0.04
Comparative example 3	70	65	28	0.03

As can be seen from the test data in the table, the foam material obtained by the embodiment of the invention has smaller cell size, and the smaller cell size is less than 50 mu m, so that the foam material has good comprehensive performance; the rebound rate of the foaming material is above 60%, and the rebound performance is obviously superior to that of polystyrene, polypropylene and the like; the dielectric loss tangent value of the embodiment of the invention is more than 0.5, and the invention has better electromagnetic wave absorption effect.

The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims

1. A high-resilience wave-absorbing foaming material is prepared from the following components in parts by weight:

20-95 parts of PBAT resin;

5-80 parts of thermoplastic elastomer;

0.5-10 parts of bridging agent;

0.2-3 parts of an anti-hydrolysis agent;

0.1-2 parts of a cell regulator;

2-20 parts of wave-absorbing auxiliary agent;

the bridging agent is one or more of ethylene-methyl methacrylate copolymer, nitrile rubber, vinyl triethoxysilane and styrene-glycidyl methacrylate copolymer;

the wave-absorbing auxiliary agent is one or more of carbon fiber, carbon black, graphene, carbon nano tube, silicon carbide, polyaniline and poly-p-phenylacetylene;

the rebound wave-absorbing foaming material is prepared according to the following steps:

2. The high resilience wave-absorbing foam according to claim 1, wherein the thermoplastic elastomer is one or more of styrene elastomer, polyolefin elastomer, polyurethane elastomer, polyamide elastomer, polyester elastomer, vulcanized rubber and ethylene-vinyl acetate copolymer.

3. The high resilience wave-absorbing foam material according to claim 1, wherein the anti-hydrolysis agent is one or more of carbodiimide and polycarbodiimide.

4. The method for preparing the high resilience wave-absorbing foam material according to claim 1, comprising the following steps:

5. The method according to claim 4, wherein the step a) is performed by using an extruder, and the temperature of the extruder is 120-220 ℃; the rotating speed of the extruder is 80-300 r/min.

6. The method according to claim 4, wherein the step B) is performed by supercritical foaming using a supercritical gas, wherein the supercritical gas is carbon dioxide or a mixture of carbon dioxide and nitrogen.

7. The method according to claim 6, wherein the temperature of the supercritical foaming is 70-120 ℃, the pressure of the supercritical foaming is 6-20 mpa, and the heat preservation and pressure maintaining time of the supercritical foaming is 0.5-3 hours.

8. The preparation method of claim 7, wherein the pressure release rate of supercritical foaming is 1-20 mpa/s.

9. The method according to claim 4, wherein the hot press forming temperature is 50-100 ℃, the hot press forming pressure is 0.1-5 mpa, and the hot press forming time is 1-10 min.