In-mold foaming wave-absorbing type rigid plastic foam material and preparation method thereof

Abstract

The invention discloses a preparation method of a wave-absorbing type in-mold foaming rigid plastic foam material, which is characterized by comprising the following steps: mixing rigid plastic pre-foaming particles obtained by pre-foaming rigid plastic polymer particles with an adhesive and a wave-absorbing agent, and carrying out in-mold re-foaming to obtain the wave-absorbing type in-mold foaming rigid plastic foam material.

Description

Technical Field

[0001] The present application relates to the technical field of material preparation, and in particular to a wave-absorbing rigid plastic foam material and a preparation method and application thereof. Background Art

[0002] Rigid foam plastics are a type of foam material with good mechanical and thermal insulation properties. They often have high compressive strength and elastic modulus, strong compressive resistance, and can be used in fields such as construction and vehicle manufacturing that need to withstand large loads. Common materials include polystyrene, polyurethane, polyethylene, and polypropylene materials. Among them, polymethacrylimide (PMI) foam material is a cross-linked rigid closed-cell foam with outstanding structural stability and mechanical properties. It is currently the heat-resistant foam plastic with the highest strength and stiffness. It can achieve one-time co-curing of composite sandwich structures. It has an important position and wide application in many high-tech fields such as aerospace, rail transportation, wind power generation, ships, and new energy vehicles.

[0003] However, most of the existing rigid foam plastics are wave-transmitting foams, which cannot be used in special fields such as electromagnetic shielding that require wave absorption. The survivability and attack protection capabilities of traditional combat weapon systems require the support of electromagnetic shielding and stealth technology, so the research and development of wave-absorbing rigid plastic foam materials has become a new focus. Some of the developed wave-absorbing rigid plastic materials in the prior art have defects such as uneven dispersion of wave-absorbing materials, weak wave-absorbing performance, small wave-absorbing range, low foaming rate, and gaps and cracks in the foam. Therefore, the development of rigid plastic foam materials that have good wave-absorbing performance and can maintain excellent mechanical properties of the foam is still the current research direction. Summary of the invention

[0004] The purpose of the present application is to provide an in-mold foamed wave-absorbing rigid plastic foam material, which has good electromagnetic wave absorption function while maintaining the excellent mechanical properties of the foam material.

[0005] Specifically, the present application provides a method for preparing a wave-absorbing in-mold foamed rigid plastic foam material, which is characterized in that the rigid plastic pre-foamed particles obtained by pre-foaming rigid plastic polymer particles are mixed with an adhesive and an absorbent, and then re-foamed in the mold to obtain the wave-absorbing in-mold foamed rigid plastic foam material.

[0006] Furthermore, the hard plastic polymer particles in the preparation method are obtained by granulating hard plastic prepolymers.

[0007] Furthermore, the hard plastic prepolymer is one or more of PMI prepolymer, PMMA prepolymer, PET prepolymer and PEI prepolymer.

[0008] Furthermore, the particle size of the granulation is 150-4000 microns.

[0009] Furthermore, in the preparation method, the hard plastic polymer particles are foamed at a temperature of 140-250° C., a foaming time of 0.1-10 h, and a foaming density of 30-200 kg / m 3 The pre-foaming treatment is carried out under the conditions of to obtain the hard plastic pre-foamed particles.

[0010] Furthermore, the adhesive in the preparation method is obtained by dissolving a polymer of acrylonitrile and / or methacrylonitrile, acrylic acid and / or methacrylic acid, an interfacial modifier and an initiator in a solvent.

[0011] Further, the interface modifier is selected from one or more of glycidyl methacrylate, silane coupling agent KH550, silane coupling agent KH560, silane coupling agent KH602, titanate coupling agent, aluminate coupling agent, BYK106, BYK110. Preferably, the interface modifier is a titanate coupling agent.

[0012] Furthermore, the initiator is selected from one or more of tert-amyl peroxyacetate, benzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-amyl peroxybenzoate, tert-butyl peroxybenzoate, azobisisobutyronitrile and azoisobutylcyanamide.

[0013] Furthermore, the solvent is selected from one or more of tetrahydrofuran, DMF, DMAC, NMP, ethanol, isopropanol, n-hexane isopropanol, n-butanol, isobutanol, tert-butanol, tert-amyl alcohol, hexanol, urea, methyl urea, and dimethyl urea.

[0014] Furthermore, the absorber in the preparation method is selected from one or more of carbon nanotubes, graphene, carbon black, carbon powder, porous carbon, carbon aerogel, iron oxides, magnetic metal and alloy nanoparticles, magnetic nanometal oxides and carbonyl iron.

[0015] Furthermore, in the preparation method, the adhesive and the absorber are first mixed and dispersed for a certain period of time to obtain a mixed solution, which is then mixed with the rigid plastic pre-foamed particles.

[0016] Furthermore, when the adhesive and the absorber are mixed, the mass ratio of the adhesive to the absorber is 0.1-10:10-95.

[0017] Furthermore, when the mixed solution is mixed with the rigid plastic pre-foamed particles, the mass ratio of the rigid plastic pre-foamed particles to the mixed solution is 50-95:5-10.

[0018] Furthermore, in the preparation method, the foaming temperature during in-mold re-foaming is 140-250° C., and the foaming time is 0.1-10 h.

[0019] The present application also provides a wave-absorbing in-mold foaming rigid plastic foam material, which is prepared by the preparation method provided in the present application.

[0020] The present application also provides the application of the wave-absorbing in-mold foaming rigid plastic foam material in the fields of aviation, aerospace, military industry, and anti-electromagnetic shielding materials.

[0021] Effects of the Invention

[0022] The wave-absorbing in-mold foaming rigid plastic foam material provided in the present application is prepared by mixing a special adhesive containing a rigid plastic prepolymer (such as PMI) raw material and an interface modifier with an absorber and then foaming it in-mold with rigid plastic pre-foamed particles. The absorber is uniformly dispersed during the foaming process through molecular bonding, is not easy to settle, prevents subsequent agglomeration, and effectively improves the wave-absorbing performance of the rigid plastic foam. At the same time, compared with conventional epoxy resins and phenolic resins, the adhesive in the present application contains rigid plastic raw materials and interface modifier components, which can improve the interfacial bonding strength between pre-foamed particles and improve mechanical properties such as tensile strength. At the same time, the preparation method can form a core-shell structure with pre-foamed particles as the core and adhesives and absorbers as the shell, and make the connection between pre-foamed particles and between pre-foamed particles and absorbers tighter, effectively improving the defects of curing, increased system viscosity, and foam voids caused by resin components in the prior art. The in-mold foaming technology in the present application can directly foam and shape in the mold, reducing subsequent processing costs and increasing material utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Test results of wave absorption performance of wave absorbing rigid plastic foam DETAILED DESCRIPTION

[0024] The present application is further described in detail below in conjunction with specific implementation methods. The examples given are intended to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0025] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the functional differences of components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" are open-ended terms and should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present application, but the description is based on the general principles of the specification and is not intended to limit the scope of the present application. The scope of protection of the present application shall be determined by the attached claims.

[0026] The present application relates to a method for preparing a wave-absorbing in-mold foamed rigid plastic foam material, which is characterized in that the rigid plastic pre-foamed particles obtained by pre-foaming rigid plastic polymer particles are mixed with an adhesive and a wave-absorbing agent, and then foamed in the mold to obtain the wave-absorbing in-mold foamed rigid plastic foam material.

[0027] In a specific embodiment, the hard plastic polymer particles are obtained by granulating hard plastic prepolymers.

[0028] The hard plastic prepolymer in the present application may be one or more of PMI prepolymer, PMMA prepolymer, PET prepolymer, and PEI prepolymer.

[0029] PMI (polymethacrylimide) is currently the heat-resistant foam plastic with the highest strength and stiffness, and has outstanding structural stability and mechanical properties. However, most common PMI materials are wave-transmitting foams, and their application is limited in fields that require electromagnetic shielding functions. The PMI material provided in this application is improved by adding an absorbent and using an adhesive of a specific component to improve its performance, so that the material can achieve good electromagnetic wave absorption effect while maintaining excellent mechanical properties.

[0030] PMMA (polymethyl methacrylate) is a long-chain high molecular polymer with high mechanical strength. It has high tensile and impact resistance. The processed PMMA can be used as bulletproof glass or military aircraft cockpit covers.

[0031] PET (polyterephthalate) is a polyester thermoplastic resin with good creep resistance, fatigue resistance, abrasion resistance and dimensional stability, low wear and high hardness, and the greatest toughness among thermoplastics.

[0032] PEI (polyetherimide) is a super engineering plastic made of amorphous polyetherimide. It has the best high temperature resistance and dimensional stability. It has high strength, high rigidity, wear resistance and dimensional stability at high temperatures. It can be widely used in high temperature resistant terminals, aircraft internal parts, medical equipment and other fields.

[0033] In a preferred embodiment, the duroplastic prepolymer may be a PMI prepolymer.

[0034] In a specific embodiment, the PMI prepolymer is obtained by uniformly mixing acrylonitrile and / or methacrylonitrile, acrylic acid and / or methacrylic acid, an initiator, a foaming agent, and a nucleating agent and then polymerizing them.

[0035] In a preferred embodiment, the mass ratio of acrylonitrile and / or methacrylonitrile, acrylic acid and / or methacrylic acid, initiator, foaming agent and nucleating agent during polymerization is 20-45:20-50:1-5:1-10:0.5-1; the polymerization temperature is 45-80°C, and the polymerization time is 60-240h.

[0036] Among them, preferably, the initiator is selected from one or more of tert-amyl peracetate, benzoyl peroxide, tert-butyl peroxy 2-ethylhexanoate, tert-amyl perbenzoate, tert-butyl perbenzoate, azobisisobutyronitrile and azoisobutylcyanoformamide; the foaming agent is selected from one or more of ethanol, propanol, isopropanol, water, tert-butyl alcohol and amyl alcohol; the nucleating agent is selected from one or more of silicon dioxide, titanium dioxide, aluminum oxide, benzoic acid, adipic acid, sodium benzoate, sodium acetate and boron nitride.

[0037] In a specific embodiment, the particle size of the hard plastic prepolymer after granulation is 150-4000 microns, for example, it can be 150, 200, 300, 500, 8000, 1000, 1500, 2000, 2500, 3000, 3500, 4000 microns, etc.

[0038] In a specific embodiment, the rigid plastic polymer particles are foamed at a temperature of 140-250° C., for example, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250° C., a foaming time of 0.1-10 h, for example, 0.1, 0.2, 0.5, 1.0, 2.0, 3.0, 5.0, 8.0, 10.0 h, and a foaming density of 30-200 kg / m 3， , for example, 30, 40, 50, 80, 100, 120, 150, 180, 200 kg / m 3 , and perform foaming treatment to obtain the hard plastic pre-foamed particles.

[0039] In a specific embodiment, the adhesive in the present application is obtained by dissolving a polymer of acrylonitrile and / or methacrylonitrile, acrylic acid and / or methacrylic acid, an interfacial modifier and an initiator in a solvent.

[0040] In a specific embodiment, the interface modifier is selected from one or more of glycidyl methacrylate, silane coupling agent KH550, silane coupling agent KH560, silane coupling agent KH602, titanate coupling agent, aluminate coupling agent, BYK106, BYK110. In a preferred embodiment, it is a titanate coupling agent.

[0041] In a specific embodiment, the initiator is selected from one or more of tert-amyl peroxyacetate, benzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-amyl peroxybenzoate, tert-butyl peroxybenzoate, azobisisobutyronitrile and azoisobutylcyanoformamide.

[0042] In a specific embodiment, the solvent is selected from one or more of tetrahydrofuran, DMF, DMAC, NMP, ethanol, isopropanol, n-hexane isopropanol, n-butanol, isobutanol, tert-butanol, tert-amyl alcohol, hexanol, urea, methyl urea, and dimethyl urea.

[0043] In a specific embodiment, the absorber in the present application is selected from one or more of carbon nanotubes, graphene, carbon black, carbon powder, porous carbon, carbon aerogel, iron oxides, magnetic metal and alloy nanoparticles, magnetic nanometal oxides and carbonyl iron.

[0044] In a specific embodiment, the adhesive and the absorber are first mixed and dispersed for a certain period of time to obtain a mixed solution, which is then mixed with the rigid plastic pre-foamed particles.

[0045] In a preferred embodiment, the mass ratio of the adhesive to the absorber when mixed is 0.1-10:10-95.

[0046] In a preferred embodiment, after the adhesive and the absorber are mixed, ultrasonic dispersion is performed, preferably, ultrasonic dispersion is performed for 2 hours to obtain the mixed solution.

[0047] In a specific embodiment, when the rigid plastic pre-foamed particles are mixed with the mixed solution of the adhesive and the wave absorbing agent, the mass ratio of the rigid plastic pre-foamed particles to the mixed solution is 50-95:5-10.

[0048] In a specific embodiment of the present application, when the in-mold re-foaming is performed, the foaming temperature is 160-250° C., and the foaming time is 0.1-10 h.

[0049] The preparation method of the wave-absorbing in-mold foaming rigid plastic foam material provided in the present application is to prepare the rigid plastic prepolymer through the free radical bulk polymerization reaction between the raw material components in the rigid plastic prepolymer. At the same time, the interface modifiers such as titanate interface modifier, silane interface modifier KH550 or silane interface modifier KH560 are added to raw materials such as acrylonitrile and acrylic acid to prepare the adhesive, replacing the commonly used adhesives such as epoxy resin and phenolic resin, and then the absorber is added and mixed with the pre-foamed particles, so that the absorber is evenly dispersed during the foaming process through molecular-level bonding, and is not easy to settle, which effectively improves the wave-absorbing performance of the rigid foam plastic. At the same time, the adhesive can also improve the interfacial bonding strength between the pre-foamed particles, improve the mechanical properties, and reduce the problems of voids and cracks caused by the traditional thermosetting resin as an adhesive.

[0050] The present application also relates to an absorbing in-mold foamed rigid plastic foam material, which is prepared by the preparation method provided in the present application. In the absorbing foam material, due to the addition of an adhesive containing an interface modifier, the connection between the pre-foamed particles and between the pre-foamed particles and the absorbing agent is made tighter, so that the absorbing foam material maintains good mechanical properties.

[0051] The present application also relates to the application of the wave-absorbing in-mold foaming rigid plastic foam material in the fields of aviation, aerospace, military industry, and anti-electromagnetic shielding materials.

[0052] Example

[0053] The present application provides a general and / or specific description of the materials and test methods used in the experiments. In the following examples, if there is no other special explanation, % means wt%, that is, weight percentage. Among the reagents used, PMI prepolymer was prepared by itself, PMMA prepolymer was purchased from Shanghai Miaoxin Plastic Co., Ltd., PET prepolymer was purchased from Jiangyin Nopude Technology Co., Ltd., methacrylonitrile and acrylonitrile were purchased from Ningbo Jinfei Chemical Technology Co., Ltd., methacrylic acid and acrylic acid were purchased from Ningbo Huajia Chemical Co., Ltd., and other reagents or instruments used without indicating the manufacturer are conventional reagent products or conventional experimental instruments that can be purchased commercially.

[0054] Example 1 Preparation of wave-absorbing in-mold foaming rigid plastic foam material

[0055] (1) 45 g of methacrylonitrile, 55 g of methacrylic acid, 3 g of azobisisobutyronitrile, 6 g of isopropyl alcohol, and 1 g of benzoic acid were mixed evenly, and polymerized at 45° C. for 150 h to obtain a PMI prepolymer. The PMI prepolymer crusher with a power of 30 kW was used to crush the prepolymer, and 325 μm PMI polymer particles were obtained by sieving;

[0056] (2) The PMI polymer particles obtained in the previous step were pre-foamed at a temperature of 200°C, a pre-foaming time of 3 hours, and a pre-foaming density of 130 kg / m 3 , obtaining PMI pre-expanded particles;

[0057] (3) 45 g of methacrylonitrile, 55 g of methacrylic acid, 2 g of titanate interface modifier, 3 g of azobisisobutyronitrile, 6 g of isopropyl alcohol, and 1 g of benzoic acid were mixed and polymerized at 45° C. for 150 h to form a polymer, and the polymer was added to DMF for mixing. After dissolution, an adhesive was obtained;

[0058] (4) Mix 0.5 g of the adhesive obtained in the previous step with 9.5 g of carbon nanotubes to obtain a mixed solution;

[0059] (5) Add 92 g of the PMI pre-expanded particles obtained in step (2) into 8 g of the mixed solution, mix well, and perform in-mold foaming at a temperature of 230° C. for 5 h to obtain the absorbing in-mold foamed rigid plastic foam material.

[0060] Example 2 Preparation of wave-absorbing in-mold foaming rigid plastic foam material

[0061] (1) crushing the PMMA prepolymer with a 30 kW crusher, and sieving to obtain 325 μm PMMA polymer particles;

[0062] (2) The PMMA polymer particles obtained in the previous step were pre-foamed at a temperature of 200°C, a pre-foaming time of 3 hours, and a pre-foaming density of 130 kg / m 3 , obtaining PMMA pre-expanded particles;

[0063] (3) 45 g of methacrylonitrile, 50 g of methacrylic acid, 1 g of titanate interface modifier, 1.5 g of azobisisobutyronitrile, 3 g of isopropyl alcohol, and 0.5 g of benzoic acid were mixed and polymerized at 45° C. for 150 h to form a polymer, and the polymer was added to DMF for mixing. After dissolution, an adhesive was obtained;

[0064] (4) Mix 1 g of the adhesive obtained in the previous step with 9 g of carbon nanotubes to obtain a mixed solution;

[0065] (5) Add 92 g of the PMMA pre-foamed particles obtained in step (2) into 8 g of the mixed solution, mix well, and perform in-mold foaming at a temperature of 230° C. for 5 h to obtain the absorbing in-mold foamed rigid plastic foam material.

[0066] Example 3 Preparation of wave-absorbing in-mold foaming rigid plastic foam material

[0067] (1) 45 g of methacrylonitrile, 55 g of methacrylic acid, 3 g of azobisisobutyronitrile, 6 g of isopropyl alcohol, and 1 g of benzoic acid were mixed evenly, and polymerized at 45° C. for 150 h to obtain a PMI prepolymer. The PMI prepolymer was crushed by a 20 kW PMI prepolymer crusher, and sieved to obtain 270 μm PMI polymer particles;

[0068] (2) The PMI polymer particles obtained in the previous step were pre-foamed at a temperature of 190° C., a pre-foaming time of 5 h, and a pre-foaming density of 130 kg / m 3 , obtaining PMI pre-expanded particles;

[0069] (3) 45 g of methacrylonitrile, 55 g of methacrylic acid, 2 g of titanate interface modifier, 3 g of azobisisobutyronitrile, 6 g of isopropyl alcohol, and 1 g of benzoic acid were mixed and polymerized at 70° C. for 180 h to form a polymer, and the polymer was added to DMF for mixing. After dissolution, an adhesive was obtained;

[0070] (4) Mix 1 g of the adhesive obtained in the previous step with 9 g of carbon nanotubes to obtain a mixed solution;

[0071] (5) Add 92 g of the PMI pre-foamed particles obtained in step (2) to 8 g of the mixed solution, mix well, and perform in-mold foaming at a temperature of 220° C. for 4 h to obtain the absorbing in-mold foamed rigid plastic foam material.

[0072] Example 4 Preparation of wave-absorbing in-mold foaming rigid plastic foam material

[0073] (1) crushing the prepolymer using a PET prepolymer crusher with a power of 20 kW, and sieving to obtain 270 μm PET polymer particles;

[0074] (2) The PET polymer particles obtained in the previous step were subjected to pre-foaming treatment, with a pre-foaming temperature of 190° C., a pre-foaming time of 5 h, and a pre-foaming density of 130 kg / m 3 , obtaining PET pre-expanded particles;

[0075] (3) 45 g of acrylonitrile, 55 g of acrylic acid, 2 g of silane interfacial modifier KH550, 3 g of benzoyl peroxide, 6 g of propanol, and 1 g of sodium benzoate were mixed and polymerized at 70° C. for 180 h to form a polymer, and the polymer was added to DMAC for mixing. After dissolution, an adhesive was obtained;

[0076] (4) Mix 2 g of the adhesive obtained in the previous step with 8 g of carbon black to obtain a mixed solution;

[0077] (5) Add 92 g of the PET pre-foamed particles obtained in step (2) to 8 g of the mixed solution, mix well, and perform in-mold foaming at a temperature of 220° C. for 4 h to obtain the absorbing in-mold foamed rigid plastic foam material.

[0078] Example 5 Preparation of wave-absorbing in-mold foaming rigid plastic foam material

[0079] (1) crushing the PMMA prepolymer with a 20 kW crusher, and sieving to obtain 270 μm polymethacrylimide polymer particles;

[0080] (2) The PMMA polymer particles obtained in the previous step were pre-foamed at a temperature of 190°C, a pre-foaming time of 5 hours, and a pre-foaming density of 130 kg / m 3 , obtaining PMMA pre-expanded particles;

[0081] (3) 45 g of acrylonitrile, 55 g of acrylic acid, 2 g of silane interfacial modifier KH550, 3 g of benzoyl peroxide, 6 g of propanol, and 1 g of sodium benzoate were mixed and polymerized at 70° C. for 180 h to form a polymer, and the polymer was added to DMAC for mixing. After dissolution, an adhesive was obtained;

[0082] (4) Mix 2 g of the adhesive obtained in the previous step with 8 g of carbon nanotubes to obtain a mixed solution;

[0083] (5) Add 95 g of the PMMA pre-foamed particles obtained in step (2) to 5 g of the mixed solution, mix well, and perform in-mold foaming at a temperature of 220° C. for 4 h to obtain the absorbing in-mold foamed rigid plastic foam material.

[0084] Example 6 Preparation of wave-absorbing in-mold foaming rigid plastic foam material

[0085] (1) crushing the prepolymer using a PET prepolymer crusher with a power of 20 kW, and sieving to obtain 270 μm PET polymer particles;

[0086] (2) The PET polymer particles obtained in the previous step were subjected to pre-foaming treatment, with a pre-foaming temperature of 190° C., a pre-foaming time of 5 h, and a pre-foaming density of 130 kg / m 3 , obtaining PET pre-expanded particles;

[0087] (3) 45 g of acrylonitrile, 50 g of acrylic acid, 1 g of silane interface modifier KH550, 1.5 g of benzoyl peroxide, 3 g of propanol, and 0.5 g of sodium benzoate were mixed and polymerized at 70° C. for 180 h to form a polymer, and the polymer was added to DMAC for mixing. After dissolution, an adhesive was obtained;

[0088] (4) Mix 2 g of the adhesive obtained in the previous step with 8 g of carbon black to obtain a mixed solution;

[0089] (5) Add 95 g of the PET pre-foamed particles obtained in step 2) to 5 g of the mixed solution, mix well, and perform in-mold foaming at a temperature of 220° C. for 4 hours to obtain the absorbing in-mold foamed rigid plastic foam material.

[0090] Comparative Example 1

[0091] (1) crushing the prepolymer by a PET prepolymer crusher with a power of 30 kW, and sieving to obtain 325 μm PET polymer particles;

[0092] (2) The PET polymer particles obtained in the previous step were subjected to pre-foaming treatment, with a pre-foaming temperature of 200°C, a pre-foaming time of 3 hours, and a pre-foaming density of 130 kg / m 3 , obtaining PET pre-expanded particles;

[0093] (3) Mix 0.5 g of adhesive epoxy resin and 9.5 g of carbon nanotubes to obtain a mixed solution;

[0094] (4) Add 92 g of the PET pre-expanded particles obtained in step (2) into 8 g of the mixed solution, mix well, and perform in-mold foaming at a temperature of 230° C. for 5 h to obtain a wave-absorbing PET foam material.

[0095] Comparative Example 2

[0096] (1) 45 g of methacrylonitrile, 55 g of methacrylic acid, 3 g of azobisisobutyronitrile, 6 g of isopropanol, and 1 g of benzoic acid were mixed evenly, and polymerized at 45° C. for 150 h to obtain a PMI prepolymer. The PMI prepolymer crusher with a power of 50 kW was used to crush the prepolymer, and 325 μm PMI polymer particles were obtained by sieving;

[0097] (2) The PMI polymer particles obtained in the previous step were pre-foamed at a temperature of 150° C., a pre-foaming time of 15 h, and a pre-foaming density of 130 kg / m 3 , obtaining PMI pre-expanded particles;

[0098] (3) 45 g of methacrylonitrile, 55 g of methacrylic acid, 2 g of titanate interface modifier, 3 g of azobisisobutyronitrile, 6 g of isopropyl alcohol, and 1 g of benzoic acid were mixed and polymerized at 100° C. for 50 h to form a polymer, and the polymer was added to DMF for mixing. After dissolution, an adhesive was obtained;

[0099] (4) Mix 1 g of the adhesive obtained in the previous step with 9 g of carbon powder to obtain a mixed solution;

[0100] (5) Add 95 g of the PMI pre-expanded particles obtained in step (2) into 5 g of the mixed solution, mix well, and perform in-mold foaming at a temperature of 260° C. for 3 h to obtain an absorbing PMI foam material.

[0101] Comparative Example 3

[0102] (1) crushing the PMMA prepolymer with a 30 kW crusher, and sieving to obtain 325 μm PMMA polymer particles;

[0103] (2) The PMMA polymer particles obtained in the previous step were pre-foamed at a temperature of 200°C, a pre-foaming time of 3 hours, and a pre-foaming density of 130 kg / m 3 , obtaining PMMA pre-expanded particles;

[0104] (3) 20 g of acrylonitrile, 50 g of acrylic acid, 0.5 g of silane interface modifier KH550, 1 g of benzoyl peroxide, 3 g of propanol, and 0.5 g of sodium benzoate were mixed and polymerized at 45° C. for 150 h to form a polymer, and the polymer was added to DMF for mixing. After dissolution, an adhesive was obtained;

[0105] (4) Mix 1 g of the adhesive obtained in the previous step with 9 g of carbon powder to obtain a mixed solution;

[0106] (5) Add 95 g of the PMMA pre-expanded particles obtained in step (2) to 5 g of the mixed solution, mix well, and perform in-mold foaming at a temperature of 230° C. for 5 h to obtain an absorbing PMMA foam material.

[0107] Comparative Example 4

[0108] (1) 45 g of methacrylonitrile, 55 g of methacrylic acid, 3 g of azobisisobutyronitrile, 6 g of isopropanol, and 1 g of benzoic acid were mixed evenly, and polymerized at 45° C. for 150 h to obtain a PMI prepolymer. The PMI prepolymer was crushed by a 30 kW crusher, and 325 μm PMI polymer particles were obtained by sieving;

[0109] (2) The PMI polymer particles obtained in the previous step were pre-foamed at a temperature of 200°C, a pre-foaming time of 3 hours, and a pre-foaming density of 130 kg / m 3 , obtaining PMI pre-expanded particles;

[0110] (3) 20 g of acrylonitrile, 50 g of acrylic acid, 0.5 g of silane interface modifier KH550, 1 g of benzoyl peroxide, 3 g of propanol, and 0.5 g of sodium benzoate were mixed and polymerized at 45° C. for 150 h to form a polymer, and the polymer was added to DMF for mixing. After dissolution, an adhesive was obtained;

[0111] (4) Mix 9 g of the adhesive obtained in the previous step with 1 g of the absorber to obtain a mixed solution;

[0112] (5) Add 98 g of the PMI pre-expanded particles obtained in step (2) into 2 g of the mixed solution, mix well, and perform in-mold foaming at a temperature of 230° C. for 5 h to obtain an absorbing PMI foam material.

[0113] Experimental Example 1 Determination of Mechanical Properties of Radiation-Absorbing Rigid Plastic Foam Material

[0114] The mechanical properties of the wave-absorbing foam materials obtained in the above examples and comparative examples were measured, and the results are shown in Table 1.

[0115] Among them, the apparent density is determined in accordance with "GB / T 6343-2009 Determination of apparent density of cellular plastics and rubber"; the tensile strength is determined in accordance with "ASTM-D638-2010 Plastic tensile strength"; and the compressive strength is determined in accordance with "GB / T8813-2008 Determination of compression properties of rigid cellular plastics".

[0116] Experimental Example 2: Measurement of the Absorption Performance of Absorbing Rigid Plastic Foam Material

[0117] The absorbing performance of the absorbing foam materials obtained in the above-mentioned embodiment and comparative example was measured, and the measuring method was referred to GJB2038A-2011 "Test Method for Reflectivity of Radar Absorbing Materials".

[0118] The results are shown in Table 1 and Figure 1 shown.

[0119] Table 1 Mechanical properties test results of wave-absorbing in-mold foaming rigid plastic foam materials

[0120] <![CDATA[Density (g / cm 3 )]]> Compression strength(MPa) Tensile strength(MPa) Elongation at break % Example 1 112.6 3.17 3.02 2.24 Example 2 112.2 2.89 2.71 2.06 Example 3 113.4 2.83 2.76 2.04 Example 4 117.4 2.54 2.34 1.77 Example 5 115.6 2.48 2.27 1.83 Example 6 116.2 2.23 2.02 1.64 Comparative Example 1 113.6 2.01 1.68 1.45 Comparative Example 2 116 1.85 1.52 1.35 Comparative Example 3 111.4 1.91 1.48 1.38 Comparative Example 4 115 1.84 1.56 1.28

[0121] It can be seen from the experimental results that the wave-absorbing in-mold foaming rigid plastic foam material provided by the present application has a certain electromagnetic wave absorption function at 0.6-40GHz, and can meet the use in special wave-absorbing fields such as electromagnetic shielding. At the same time, it has excellent mechanical properties, high compression strength and tensile strength, high density, and fewer defects between foamed particles, which can meet the application environment with more diverse conditions and has a wider application prospect.

[0122] The above is only the preferred embodiment of the present application, and does not limit the present application in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present application without departing from the technical solution of the present application still falls within the protection scope of the technical solution of the present application.

Claims

1. A method for preparing a wave-absorbing in-mold foaming rigid plastic foam material, characterized in that: The hard plastic pre-foamed particles obtained by pre-foaming hard plastic polymer particles are mixed with an adhesive and a wave absorbing agent, and then foamed in a mold to obtain the wave absorbing in-mold foamed hard plastic foam material.

2. The preparation method according to claim 1, wherein The hard plastic prepolymer is granulated to obtain the hard plastic polymer particles.

3. The preparation method according to claim 2, wherein The hard plastic prepolymer is one or more of PMI prepolymer, PMMA prepolymer, PET prepolymer and PEI prepolymer.

4. The preparation method according to claim 2, wherein The particle size of the granulation is 150-4000 microns.

5. The preparation method according to any one of claims 1 to 4, wherein The rigid plastic polymer particles are foamed at a temperature of 140-250° C., a foaming time of 0.1-10 h, and a foaming density of 30-200 kg / m 3 The hard plastic pre-foamed particles are obtained by performing a foaming treatment.

6. The preparation method according to claim 1, wherein The adhesive is obtained by dissolving a polymer of acrylonitrile and / or methacrylonitrile, acrylic acid and / or methacrylic acid, an interface modifier and an initiator in a solvent.

7. The preparation method according to claim 6, wherein: The interface modifier is selected from one or more of glycidyl methacrylate, silane coupling agent KH550, silane coupling agent KH560, silane coupling agent KH602, titanate coupling agent, aluminate coupling agent, BYK106, BYK110, preferably titanate coupling agent.

8. The preparation method according to claim 6, wherein: The initiator is selected from one or more of tert-amyl peroxyacetate, benzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-amyl peroxybenzoate, tert-butyl peroxybenzoate, azobisisobutyronitrile and azoisobutylcyanoformamide.

9. The preparation method according to claim 6, wherein: The solvent is selected from one or more of tetrahydrofuran, DMF, DMAC, NMP, ethanol, isopropanol, n-hexane, isopropanol, n-butanol, isobutanol, tert-butanol, tert-amyl alcohol, hexanol, urea, methyl urea and dimethyl urea.

10. The preparation method according to claim 1, wherein: The absorber is selected from one or more of carbon nanotubes, graphene, carbon black, carbon powder, porous carbon, carbon aerogel, iron oxides, magnetic metal and alloy nanoparticles, magnetic nanometal oxides and carbonyl iron.

11. The preparation method according to claim 1, wherein: The adhesive and the absorber are first mixed and dispersed for a certain period of time to obtain a mixed solution, which is then mixed with the rigid plastic pre-foamed particles.

12. The preparation method according to claim 11, wherein: When the adhesive and the absorber are mixed, the mass ratio of the adhesive to the absorber is 0.1-10:10-95.

13. The preparation method according to claim 11, wherein: The mass ratio of the hard plastic pre-foamed particles to the mixed solution is 50-95:5-10.

14. The preparation method according to claim 1, wherein: The foaming temperature of the in-mold re-foaming is 140-250° C., and the foaming time is 0.1-10 h.

15. A wave-absorbing rigid plastic foam material, which is prepared by the preparation method according to any one of claims 1 to 14.

16. Application of the wave-absorbing rigid plastic foam material according to claim 15 in the fields of aviation, aerospace, military industry, and anti-electromagnetic shielding materials.

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