Preparation method of composite wave-absorbing material, composite wave-absorbing material and railway vehicle

Abstract

The embodiment of the invention provides a preparation method of a composite wave-absorbing material, the composite wave-absorbing material and a railway vehicle, and the preparation method comprises the following steps: mixing 50%-80% by weight of polypropylene, 20%-30% by weight of a flame retardant, 5%-10% by weight of an antioxidant, 1%-5% by weight of powdery superconductive carbon nanotubes and 1%-10% by weight of nickel-plated calcium silicate; melting and plastifying the mixed materials into particles through a double-screw extruder; foaming the granular material to obtain foamed particles; the foamed particles are subjected to pre-pressing forming and then dried, and the wave-absorbing material is obtained; putting the wave-absorbing material and polyurethane into a mold for molding; and dipping and drying the molded material in the absorbent slurry to obtain the composite wave-absorbing material. The composite wave-absorbing material has better toughness, is not easy to age, and is non-toxic, harmless, flame-retardant and more excellent in environmental protection performance; in addition, the period of the preparation method is short, and the manufacturing cost is reduced while the production efficiency is improved.

Description

Technical Field

[0001] The present application relates to absorbing material technology, and in particular to a method for preparing a composite absorbing material, a composite absorbing material and a rail vehicle. Background Art

[0002] At present, the absorbing materials used in most domestic anechoic chambers are mainly of two types: soft polyurethane foam and non-woven absorbing materials. Among them, soft polyurethane foam material is a traditional absorbing material for anechoic chambers. Its preparation process includes cutting, molding, impregnation and drying. Its advantages are simple process, low cost, low equipment requirements, high production efficiency and strong absorbing ability, but the above polyurethane foam also has many shortcomings. First, during the preparation process, flame retardants and absorbers are adsorbed in the pores of polyurethane foam through impregnation treatment. As the service life increases, they are easy to fall off and cause environmental pollution; second, polyurethane foam is an open pore and easy to absorb moisture, resulting in a decrease in absorbing performance; third, in EMC anechoic chambers, in order to obtain good low-frequency performance, polyurethane foam is often made into long wedges, but after a period of use, due to its own weight, the tip of the material pyramid will bend, that is, droop, which makes the aesthetics of the anechoic chamber worse and the overall anechoic chamber performance decrease.

[0003] The preparation process of non-woven absorbing materials generally includes coating, creasing, folding and assembly processes. The advantages of this absorbing material are strong flame retardancy and better power resistance than polyurethane foam materials. However, its preparation process is relatively complicated and requires more labor, so the production efficiency is low and the cost is relatively high compared to polyurethane foam materials. Secondly, due to the large number of manual processes, product consistency is difficult to ensure, and long-term use can easily cause the absorbent and flame retardant to fall off, polluting the environment and reducing the absorbing performance.

[0004] In addition, there is also an absorbing polyurethane sponge / hard foam composite material, which uses absorbing polyurethane sponge as the matrix, fills the hard foam foaming material into the polyurethane sponge pores, and forms a hard absorbing foam after curing. The absorbing polyurethane sponge is obtained by impregnating a non-absorbing polyurethane sponge sheet with absorbent slurry multiple times and drying it. The hard foam is filled in the polyurethane sponge pores, which can be absorbing foam or non-absorbing foam. In the preparation process of this material, the drying has extremely strict temperature requirements. If the temperature is too high, the polyurethane sponge sheet will easily deform. If the temperature is too low, the resin cannot be partially cured to play a bonding role. It is easy to soak it off after dipping again, resulting in poor yield. In addition, the curing process temperature of the hard foam is 80℃~120℃, and the time is 2h~4h. The curing time of the hard foam is relatively long, resulting in a long production cycle and high cost. The foaming material of the hard foam contains isocyanate, which will threaten human health and life safety, and cannot be recycled, which will damage the environment. Furthermore, the foaming material of rigid foam is brittle, easy to age and fall apart, and difficult to carry. Summary of the invention

[0005] In order to solve one of the above technical defects, the embodiments of the present application provide a method for preparing a composite absorbing material, a composite absorbing material and a rail vehicle.

[0006] According to a first aspect of an embodiment of the present application, a method for preparing a composite absorbing material is provided, comprising:

[0007] Mixing 50%-80% of polypropylene, 20%-30% of flame retardant, 5%-10% of antioxidant, 1%-5% of powdered superconducting carbon nanotubes, and 1%-10% of nickel-plated calcium silicate in a weight ratio;

[0008] The mixed materials are melted and plasticized into granules through a twin-screw extruder;

[0009] foaming the granular material to obtain foamed particles;

[0010] Pre-pressing the foamed particles into a shape and then drying them to obtain a wave absorbing material;

[0011] Putting the absorbing material and polyurethane into a mold for forming;

[0012] The molding material is placed in the absorbent slurry, immersed and dried to obtain a composite absorbing material.

[0013] According to a second aspect of an embodiment of the present application, a composite absorbing material is provided, which is prepared by the method described above.

[0014] According to a third aspect of an embodiment of the present application, a partition panel is provided, comprising: a core material and a skin arranged on the outside of the core material, wherein the core material is made of the composite absorbing material as described above.

[0015] According to a fourth aspect of the embodiments of the present application, there is provided a rail vehicle, comprising: the partition plate as described above.

[0016] The technical solution provided in the embodiment of the present application is to mix 50%-80% polypropylene, 20%-30% flame retardant, 5%-10% antioxidant, 1%-5% powdered superconducting carbon nanotubes, and 1%-10% nickel-plated calcium silicate in a weight ratio; melt and plasticize the mixed materials into granules through a double-screw extruder; foam the granular materials to obtain foamed particles; pre-press the foamed particles and then dry them to obtain the absorbing material; put the absorbing material and polyurethane into a mold for molding; immerse and dry the molded material in the absorbent slurry to obtain a composite absorbing material. Such a composite absorbing material has a wider working frequency band, better toughness, is not easy to age during long-term work, and is easy to carry; it is non-toxic, harmless, flame-retardant, does not add any heavy metals, and has better environmental protection performance; in addition, the preparation method provided in this embodiment has a shorter cycle, reduces the material molding conditions, and reduces the manufacturing cost while improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0018] Figure 1 A flow chart of a method for preparing a composite absorbing material provided in an embodiment of the present application;

[0019] Figure 2 A process flow chart of a method for preparing a composite absorbing material provided in an embodiment of the present application. DETAILED DESCRIPTION

[0020] In order to make the technical solutions and advantages in the embodiments of the present application more clearly understood, the exemplary embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than an exhaustive list of all the embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0021] This embodiment provides a method for preparing a composite absorbing material, which is used to prepare a composite absorbing material. The material can be used to manufacture partition boards, which have a certain strength, strong absorbing ability, good vibration reduction and noise reduction effects, and are environmentally friendly and do not pollute the environment. This partition board can be used in a variety of buildings, such as factory workshops, simple houses, etc.; it can also be used in rail vehicles as partitions for toilets, electrical cabinets, and luggage storage racks.

[0022] like Figure 1 and Figure 2 As shown, the preparation method of the composite absorbing material provided in this embodiment includes:

[0023] Step 101: Mix 50%-80% of polypropylene, 20%-30% of flame retardant, 5%-10% of antioxidant, 1%-5% of powdered superconducting carbon nanotubes, and 1%-10% of nickel-plated calcium silicate in a weight ratio.

[0024] Step 102: Melt and plasticize the mixed material into granules through a twin-screw extruder.

[0025] Step 103: foaming the granular material to obtain foamed particles.

[0026] Step 104 , pre-pressing the foamed particles and then drying them to obtain the microwave absorbing material.

[0027] Step 105: Place the absorbing material and polyurethane into a mold for molding.

[0028] Step 106: Place the molding material into the absorbent slurry for immersion and drying to obtain a composite absorbing material.

[0029] The above scheme uses the absorbing material as the matrix and fills the absorbing material with polyurethane, which, after curing, forms a composite absorbing material with good toughness, environmental protection and a wider working frequency band.

[0030] This embodiment provides a specific implementation method:

[0031] The above step 101 may be performed in the following manner:

[0032] First, the granular superconducting carbon nanotubes are put into a grinder and ground into powder particles with a preset diameter, which may be about 30 nanometers.

[0033] Then, nickel sulfate, sodium hypophosphite and sodium citrate dihydrate are dissolved in distilled water, and the activated calcium silicate is put into the solution to prepare nickel-plated calcium silicate.

[0034] Then, the temperature of the mixer is preheated to about 120° C., and 50%-80% of polypropylene, 20%-30% of flame retardant, 5%-10% of antioxidant, 1%-5% of powdered superconducting carbon nanotubes, and 1%-10% of nickel-plated calcium silicate are placed in the mixer and stirred at high speed for about 30 minutes to make the mixture uniform. Conductive masterbatch can also be added during the process.

[0035] The above step 102 is specifically as follows: putting the mixed material in step 101 into a twin-screw extruder, so that the mixed material is fully dispersed and plasticized at a preset temperature, and the preset temperature may be about 190°C.

[0036] The mixed material is extruded through a die head by drawing, with a diameter of about 1mm. Then it is cut into particles of uniform length by a high-precision tool, with a particle length of about 1mm. Then the particles with too small length are filtered out by a vibrating screen to obtain high polymer polypropylene PP particles.

[0037] The above step 103 is specifically as follows: the granular material (i.e., PP particles) obtained in step 102 is placed in a reactor, the temperature in the reactor is controlled at about 140°C, carbon dioxide is introduced into the reactor, and foaming is performed under a preset pressure, and the pressure is instantly released into the atmosphere to obtain foamed particles. The preset pressure can be 4.5 MPa, and the foaming ratio is 15 times.

[0038] The above step 104 is specifically as follows: the material foamed in the reaction kettle in step 103 is placed in a pre-pressing tank for pre-pressing, and is formed into an absorbing skeleton by high-pressure steam at a pressure of 4 MPa for a pre-pressing time of 12 hours. Then the pre-pressed absorbing material is placed in a drying room for drying at a drying temperature of about 80° C. for 2 hours to obtain a dry absorbing material.

[0039] Nickel-plated calcium silicate can withstand high temperatures of 1540°C, can enhance the toughness of foamed products, improve tensile strength, and prevent products from aging easily; nickel-plated calcium silicate itself is conductive, and when combined with conductive masterbatches and superconducting carbon nanotubes, it can form a material with better conductive properties, which plays a positive role in improving the material's wave absorption and broadening the working frequency band of the wave-absorbing material.

[0040] In addition, carbon dioxide foaming is adopted without adding any foaming agent, thus avoiding the use of toxic foaming agents. Generally, foaming agents will weaken the flame retardant effect, so this embodiment is more environmentally friendly.

[0041] The above step 105 is specifically as follows: placing the shaped absorbing material obtained in step 104 into an absorbing structure mold and applying a release agent, and then pouring polyurethane into the absorbing structure mold for foaming at a foaming temperature of about 25° C. to obtain an absorbing foamed polypropylene (EPP) / polyurethane composite absorbing material.

[0042] Before or after step 105, the method further includes the step of preparing absorbent slurry, specifically, weighing a certain mass of conductive carbon black, carbon nanotube powder, and modified epoxy resin, pouring them into plasma water, and stirring them thoroughly to obtain absorbent slurry. The mass ratio of the total mass of the conductive carbon black, carbon nanotube powder, and modified epoxy resin to the plasma water is 5:1, for example, the total mass of the conductive carbon black, carbon nanotube powder, and modified epoxy resin is 1 kg, and the plasma water level is 5 kg.

[0043] The above step 106 is specifically as follows: the molding material (i.e., the absorbing EPP / polyurethane composite material) is immersed in the absorbent slurry, and then dried at 100°C-120°C for 3 times to solidify the absorbent slurry, and finally a composite absorbing material is obtained. The composite material improves the working frequency band of the absorbing material in terms of performance, and due to the presence of the EPP absorbing material, the overall material has better toughness, is not easy to age, and is easy to install or carry.

[0044] The conventional performance test results of the composite absorbing material obtained in the above steps are shown in the following table:

[0045]

[0046] It can be seen from the test data that the absorbing EPP / polyurethane composite material obtained in this embodiment is light in weight, heat-resistant, aging-resistant, tough, environmentally friendly, has a wider operating frequency band, and can be installed in areas with more displacements, such as shielding doors, movable test probes, etc.

[0047] The technical solution provided in this embodiment is to mix 50%-80% of polypropylene, 20%-30% of flame retardant, 5%-10% of antioxidant, 1%-5% of powdered superconducting carbon nanotubes, and 1%-10% of nickel-plated calcium silicate in a weight ratio; melt and plasticize the mixed materials into granules through a double-screw extruder; foam the granular materials to obtain foamed particles; pre-press the foamed particles and then dry them to obtain the absorbing material; put the absorbing material and polyurethane into a mold for molding; immerse and dry the molded material in absorbent slurry to obtain a composite absorbing material. Such a composite absorbing material has a wider working frequency band, better toughness, is not easy to age during long-term work, and is easy to carry; it is non-toxic, harmless, flame-retardant, does not add any heavy metals, and has better environmental protection performance; in addition, the preparation method provided in this embodiment has a shorter cycle, reduces the material molding conditions, and reduces the manufacturing cost while improving production efficiency.

[0048] On the basis of the above solutions, this embodiment also provides a composite absorbing material, which is prepared by any of the above methods and has the same technical effect as the above solutions.

[0049] The composite absorbing material can be used for partition boards, which include a core material and a skin arranged outside the core material, and the core material is made of the composite absorbing material. The partition board can be used as a partition board of a building or a vehicle, and has the same technical effect as the composite absorbing material.

[0050] This embodiment also provides a rail vehicle, comprising the partition plate. The partition plate is arranged in the vehicle compartment to divide areas such as toilets, electrical cabinets, luggage racks, etc., and has the same technical effect as the composite absorbing material.

[0051] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0052] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0053] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0054] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0055] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for preparing a composite absorbing material, characterized in that: include: Mixing 50%-80% of polypropylene, 20%-30% of flame retardant, 5%-10% of antioxidant, 1%-5% of powdered superconducting carbon nanotubes, and 1%-10% of nickel-plated calcium silicate in a weight ratio; The mixed materials are melted and plasticized into granules through a twin-screw extruder; foaming the granular material to obtain foamed particles; Pre-pressing the foamed particles into a shape and then drying them to obtain a wave absorbing material; Putting the absorbing material and polyurethane into a mold for forming; The molding material is placed in the absorbent slurry, immersed and dried to obtain a composite absorbing material.

2. The preparation method according to claim 1, characterized in that: Mixing 50%-80% of polypropylene, 20%-30% of flame retardant, 5%-10% of antioxidant, 1%-5% of powdered superconducting carbon nanotubes, and 1%-10% of nickel-plated calcium silicate in a weight ratio, including: Putting granular superconducting carbon nanotubes into a grinder and grinding them into powder particles with a preset diameter; Dissolve nickel sulfate, sodium hypophosphite and sodium citrate dihydrate in distilled water, and add activated calcium silicate into the solution to prepare nickel-plated calcium silicate; Preheat the temperature of the mixer, then put 50%-80% of polypropylene, 20%-30% of flame retardant, 5%-10% of antioxidant, 1%-5% of powdered superconducting carbon nanotubes, and 1%-10% of nickel-plated calcium silicate into the mixer and stir to make the mixture uniform.

3. The preparation method according to claim 2, characterized in that: The mixed materials are melted and plasticized into granules through a twin-screw extruder, including: The mixed materials are placed into a twin-screw extruder to disperse and plasticize the mixed materials at a preset temperature; The mixed material is extruded and cut into granules.

4. The preparation method according to claim 3, characterized in that: The granular material is foamed to obtain foamed particles, comprising: placing granular material into a reaction vessel; Carbon dioxide is introduced into the reactor and foaming is performed under a preset pressure to obtain foamed particles.

5. The preparation method according to claim 4, characterized in that: The expansion ratio of the foaming in the reactor was 15 times.

6. The preparation method according to claim 1, characterized in that: Also includes: Prepare absorbent slurry, including: Pour conductive carbon black, carbon nanotube powder and modified epoxy resin into plasma water and stir to obtain absorbent slurry; The mass ratio of the total mass of the conductive carbon black, the carbon nanotube powder, and the modified epoxy resin to the plasma water is 5:

1.

7. The preparation method according to claim 6, characterized in that: The molding material is immersed in the absorbent slurry and dried, including: Dipping the molding material into the absorbent slurry; Dry at 100℃-120℃ for 3 times to solidify the absorbent slurry.

8. A composite absorbing material, characterized in that: The method is prepared by any one of claims 1 to 7.

9. A partition board, characterized in that: include: A core material and a skin arranged outside the core material, wherein the core material is made of the composite absorbing material described in claim 8.

10. A rail vehicle, characterized in that: include: The partition panel as claimed in claim 9.

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