A method for preparing a foam sandwich composite having sound insulation properties

Abstract

The application relates to a preparation method of a foam sandwich composite material with sound insulation characteristics, which comprises the following steps: laminating a thermal expansion resin sheet and other sheets together, placing the laminated sheets in a mold for curing and foaming treatment, and then cooling the sheets to room temperature at room temperature to obtain the foam sandwich composite material with sound insulation characteristics; the thermal expansion resin sheet is an epoxy resin sheet containing thermal expansion microspheres, the other sheets are prepreg skins, or the other sheets are prepreg skins and aramid honeycomb paper; the thermal expansion pressure of the thermal expansion resin sheet is 0.5-1 MPa; the absolute value of the difference between the forming processing temperature of the thermal expansion resin sheet and the forming processing temperature of the prepreg skin is not more than 20 DEG C; and the curing and foaming treatment temperature is 10-20 DEG C higher than the minimum foaming temperature of the thermal expansion microspheres. The application can prepare a high-sound-insulation foam sandwich composite material with excellent performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer composite materials, and in particular to a preparation method of a foam sandwich composite material with sound insulation properties. BACKGROUND

[0002] With the gradual improvement of human technology level, the noise generated by large-scale mechanical equipment, vehicles and household appliances has a more and more serious impact on human life. At present, the most commonly used means is to reduce noise in the transmission path, and the main acoustic control means adopted are damping noise reduction, sound absorption noise reduction and sound insulation noise reduction.

[0003] Studies have shown that, compared with traditional materials with single function, the surface skin material of the foam sandwich structure has high reflectivity to sound waves, and the foam core material inside has sound absorption performance, so that the foam sandwich structure composite material exhibits excellent sound insulation performance, becoming a research hotspot in the field of noise reduction.

[0004] Patent CN109551858B discloses a manufacturing method of a sewing foam sandwich composite material, which first prepares a foam core, then sews a fiber cloth or a prepreg on the foam core by sewing, and finally solidifies the prepreg into a shape by a hot press tank. This method has low cost, but the manufacturing process is slightly cumbersome, and the sewing method may damage the foam core and the skin, resulting in a decrease in mechanical properties.

[0005] Patent CN115798444A discloses a polymer-based low-frequency sound absorption structure and a manufacturing method thereof, which uses melamine foam as a sound absorption layer, polyurethane as an intermediate transition layer, and hollow sphere polymer as an outer layer. The sound absorption structure has good sound absorption performance and can meet different application environments. However, the sound insulation foam made by this method may have weak mechanical properties, and the preparation process is slightly cumbersome.

[0006] Patent CN107083019B discloses a sound insulation composite material and a preparation method thereof. The composite material uses a foaming resin system and a three-dimensional fiber fabric as raw materials, the three-dimensional fiber fabric is pre-solidified into a shape by a polymer system, and finally the foaming resin system is injected into the hollow sandwich structure of the three-dimensional fiber fabric to perform in-situ foaming and composite curing. The manufacturing principle is simple, the sound insulation performance is good, but there may be problems in large-scale production. SUMMARY

[0007] The purpose of the present application is to solve the problems existing in the prior art and provide a preparation method of a foam sandwich composite material with sound insulation properties.

[0008] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0009] A method for preparing a foam sandwich composite material with sound insulation properties, the method comprising the steps of: stacking a heat-expandable resin sheet and other sheets together, placing the stacked sheets in a mold for curing and foaming, and cooling the stacked sheets to room temperature to obtain the foam sandwich composite material with sound insulation properties.

[0010] The heat-expandable resin sheet is an epoxy resin sheet containing heat-expandable microspheres, and the other sheets are prepreg skins or prepreg skins and aramid honeycomb paper.

[0011] The heat-expandable resin sheet has a heat-expandable pressure of 0.5-1 MPa, and the absolute value of the difference between the molding processing temperature of the heat-expandable resin sheet and the molding processing temperature of the prepreg skin is not more than 20℃.

[0012] The room temperature is 15-30℃.

[0013] In the conventional method for combining a skin and a core material, the interface bonding force between the skin and the core material is improved by means of gluing, sewing or web reinforcement. In the present application, the heat-expandable resin sheet and other sheets including prepreg skins are cured and molded under heating. During the heating process, the heat-expandable resin sheet expands to generate an expansion force, so that the heat-expandable resin penetrates into the prepreg skin and the wettability of the heat-expandable resin and fibers in the prepreg skin is improved. Under the action of a curing agent, the resin in the prepreg skin forms cross-linking bonds with the heat-expandable resin. All the resins and the fibers in the prepreg skin are combined more closely under the action of the expansion force, so that the air bubbles remaining in the fibers in the prepreg skin and the air bubbles between the interface of the prepreg skin and the heat-expandable resin are eliminated, and the interface bonding force between the resin and the fibers is improved. Therefore, the interface bonding force of the molding process is superior to that of the conventional combining method.

[0014] In order to ensure that the expansion force is large enough to penetrate the heat-expandable resin into the prepreg skin, the heat-expandable pressure of the heat-expandable resin sheet is controlled to be 0.5-1 MPa, and the temperature of the curing and foaming process is controlled to be 10-20℃ higher than the minimum foaming temperature of the heat-expandable microspheres.

[0015] In order to ensure that the resin in the prepreg skin forms cross-linking bonds with the heat-expandable resin under the action of a curing agent, the molding processing temperature of the heat-expandable resin sheet is controlled to be similar to the molding processing temperature of the prepreg skin. During the curing and foaming process, the heat-expandable resin expands and cures at the same time, and the resin in the corresponding prepreg skin also cures at the same time. Thus, the same curing process is used, the cross-linking reaction between the heat-expandable resin and the resin in the prepreg skin is increased, and the bonding force between the prepreg skin and the heat-expandable resin is further improved.

[0016] The present application can introduce a honeycomb structure in the composite material, which can improve the sound insulation performance, because: for the loss absorption of sound waves, the introduction of aramid honeycomb can bring more cell areas, and the existence of the cell can cause multiple reflection loss to the sound waves incident into the cell to achieve the effect of sound insulation. A certain shape and size can only effectively absorb the corresponding frequency of the wavelength, and the more the cell exists, the more the sound absorption unit is formed, which is helpful for the loss of sound waves, and by introducing the honeycomb cell with different shapes or sizes, the consumption of sound waves can be achieved for different frequencies of the wavelength. It is difficult to introduce a foam structure in the honeycomb cell by combining the traditional prepreg skin with the honeycomb structure, and generally, wood fibers such as cotton and hemp are filled to improve the sound insulation performance, and the self-made heat-expandable resin can be used to fill the honeycomb cell during the heat expansion process, and the bonding force between the prepreg skin and the aramid honeycomb paper is improved.

[0017] As a preferred technical solution:

[0018] The preparation method of the foam sandwich composite material with sound insulation properties as described above, the epoxy resin used for preparing the heat-expandable resin sheet is a bisphenol A type epoxy resin or a bisphenol F type epoxy resin.

[0019] The preparation method of the foam sandwich composite material with sound insulation properties as described above, the preparation process of the heat-expandable resin sheet is as follows:

[0020] (1) Put the epoxy resin in a water bath at 70-90℃ for 20-30min;

[0021] (2) Stir at a stirring speed of 200-300r / min until the viscosity remains unchanged for 5-10min;

[0022] (3) Reduce the stirring speed to 50-80r / min, and add the curing agent, coupling agent, surfactant and heat-expandable microspheres to the epoxy resin while stirring, or further add the flame retardant;

[0023] (4) Increase the stirring speed to 400-600r / min and stir for 60min to obtain a mixed solution;

[0024] (5) The heat-expandable resin sheet is prepared from the mixed solution by using a prepreg equipment.

[0025] The preparation method of the foam sandwich composite material with sound insulation properties as described above, the addition amount of each component in the preparation process of the heat-expandable resin sheet is: epoxy resin 100 parts, curing agent 10-20 parts, heat-expandable microspheres 5-15 parts, coupling agent 1-5 parts, surfactant 1-3 parts, and flame retardant 0-10 parts by weight.

[0026] The preparation method of the foam sandwich composite material with sound insulation properties as described above, the curing agent is an aliphatic polyamine curing agent (such as diethylene tetramine), an aromatic polyamine (such as m-phenylenediamine) or an anhydride curing agent (such as maleic anhydride);

[0027] The shell of the heat-expandable microsphere is a thermoplastic resin, and the inside is a heat-expandable hydrocarbon gas; the minimum foaming temperature of the heat-expandable microsphere is 110-120℃, and the maximum foaming temperature is 130-150℃;

[0028] The coupling agent is a silane coupling agent (such as KH550, KH560);

[0029] The surfactant is a fatty acid surfactant or an aliphatic ester surfactant;

[0030] The flame retardant is an organic phosphate flame retardant (such as tris(chloroethyl) phosphate, tris(2,3-dichloropropyl) phosphate, dimethyl methylphosphonate) or a bromine-containing aromatic flame retardant (such as hexabromobenzene).

[0031] The preparation method of the foam sandwich composite material with sound insulation properties as described above, the thickness of the heat-expandable resin sheet is 0.1-3mm; the prepreg skin is a carbon fiber prepreg or a glass fiber prepreg; the thickness of the prepreg skin is 0.1-0.15mm; the thickness of the aramid honeycomb paper is 3-20mm.

[0032] The preparation method of the foam sandwich composite material with sound insulation properties as described above, when the other sheet is a prepreg skin, the heat-expandable resin sheet and the prepreg skin are alternately laid, and the prepreg skin is more than the heat-expandable resin sheet by 1; when the other sheet is a prepreg skin and an aramid honeycomb paper, there is at least 1 prepreg skin on both sides of each aramid honeycomb paper.

[0033] The preparation method of the foam sandwich composite material with sound insulation properties as described above, the obtained laminate has a 3-layer structure, and the prepreg skin, the heat-expandable resin sheet, and the prepreg skin are sequentially arranged from top to bottom;

[0034] Alternatively, the obtained laminate has a 5-layer structure, and the prepreg skin, the heat-expandable resin sheet, the prepreg skin, the heat-expandable resin sheet, and the prepreg skin are sequentially arranged from top to bottom;

[0035] Alternatively, the obtained laminate has a 4-layer structure, and the prepreg skin, the heat-expandable resin sheet, the aramid honeycomb paper, and the prepreg skin are sequentially arranged from top to bottom;

[0036] Alternatively, the obtained laminate has a 5-layer structure, and the prepreg skin, the heat-expandable resin sheet, the aramid honeycomb paper, the heat-expandable resin sheet, and the prepreg skin are sequentially arranged from top to bottom;

[0037] Alternatively, the obtained laminated body has a 7-layer structure, and the pre-preg skin, the heat-expandable resin sheet, the aramid honeycomb paper, the pre-preg skin, the aramid honeycomb paper, the heat-expandable resin sheet and the pre-preg skin are sequentially arranged from top to bottom.

[0038] The preparation method of the foam sandwich composite material with sound insulation characteristics as described above, the curing and foaming treatment time is 1-2h.

[0039] The preparation method of the foam sandwich composite material with sound insulation characteristics as described above, the compression strength of the foam sandwich composite material with sound insulation characteristics is 5.5-15MPa, and the average sound insulation of the foam sandwich composite material with sound insulation characteristics at the frequency of 400-5000Hz is 50-80dB.

[0040] Advantages:

[0041] (1) The heat-expandable microspheres have good regulation and control effects on the pore size and uniform distribution of the epoxy foam, and the heat expansion of the microspheres can not only obtain dense pores, but also make the pores uniformly distributed, thereby providing a structural basis for the lightweight and high-strength performance of the foam.

[0042] (2) The heat-expandable resin has simple manufacturing process, low cost, and is easy to mass-produce, and the prepared epoxy foam material has excellent sound insulation performance.

[0043] (3) The foam-filled honeycomb sandwich structure has a great promoting effect on the reflection and sound insulation of sound waves, has a good loss effect on the reflection of sound waves, and the combination of the high-strength skin and the honeycomb structure with the foam can obtain a composite material structure with more excellent mechanical properties.

[0044] (4) The heat-expandable epoxy foam sheet with sound insulation characteristics can be cut according to the shape of the mold, and then subjected to heating and foaming treatment and post-treatment, so as to obtain a sound insulation functional epoxy resin composite foam structure with good sound insulation performance, mechanical properties and heat resistance.

[0045] (5) The epoxy resin composite foam sound insulation material has good sound insulation performance, heat resistance and mechanical properties, and can avoid the complex process manufacturing problem existing in the processing process of the special-shaped material, thereby reducing the waste of materials. DETAILED DESCRIPTION

[0046] Figure 1 The foam pore morphology characterization diagram of the heat-expandable resin sheet prepared by the present application after foaming;

[0047] Figure 2 The sound insulation performance curve diagram of the foam sandwich composite material of the present application example 1-5;

[0048] Figure 3 Sound insulation performance curve of the foam sandwich composite material of embodiment 6-10 of the present application. DETAILED DESCRIPTION

[0049] The application will be further described with reference to the following embodiments. It should be understood that these embodiments are only used to illustrate the application and not intended to limit the scope of the application. Furthermore, it should be understood that after reading the content of the present application, those skilled in the art can make various modifications or changes to the application, and these equivalent forms also fall within the scope of the appended claims.

[0050] The following are the test methods for the relevant performance in each embodiment:

[0051] Thermal expansion pressure: the expansion force of the resin sheet is tested by using a universal testing machine (Shenzhen Lambotest LD26.10) with an environmental test chamber. The foaming temperature of the environmental test chamber is set to 130℃. The resin sheet will be heated and expanded at 120℃, and the expansion force will be recorded in real time by the sensor of the testing machine. The maximum thermal expansion pressure of the resin sheet is obtained by dividing the maximum expansion force by the corresponding area.

[0052] Compression strength: the compression fixture of the universal testing machine (Shenzhen Lambotest LD26.10) is used to compress the foam material in the Z direction. The maximum compression stress within 10% of the deformation is divided by the cross-sectional area of the foam to obtain the compression strength of the foam.

[0053] Average sound insulation: the sound insulation performance of the foam composite material is tested in the frequency band of 400-5000Hz by using the test principle of four-probe impedance tube and the method of transmission loss test. The sound wave loss value in the 1 / 3 octave band (i.e. the frequency band most easily accepted by the human ear) is taken as the test sound insulation, and the average sound insulation is obtained by dividing the total sound insulation in these bands by the number of bands.

[0054] In the following embodiments, the type of epoxy resin has little effect on the sound insulation performance of the foam sandwich composite material with sound insulation characteristics, because the foam sandwich composite material with sound insulation characteristics mainly relies on the thermal expansion microspheres inside for sound wave loss absorption.

[0055] In the following embodiments, the cell edge length of aramid honeycomb paper has a great effect on the sound insulation performance of the foam sandwich composite material with sound insulation characteristics. Experiments show that other parameters of aramid honeycomb paper have little effect on the sound insulation performance of the foam sandwich composite material with sound insulation characteristics, so they will not be described here.

[0056] Embodiment 1

[0057] A method for preparing a foam sandwich composite material with sound insulation properties, comprising the following steps:

[0058] (1) Preparation of raw materials;

[0059] Epoxy resin: South Asia Epoxy Resin 128;

[0060] Curing agent: diethylene triamine;

[0061] Coupling agent: KH550;

[0062] Flame retardant: dimethyl methylphosphonate;

[0063] Surfactant: Tween 80;

[0064] Thermally expandable microspheres: manufacturer: Nolane Company, brand: 051DU40, minimum foaming temperature: 110℃, maximum foaming temperature: 130℃;

[0065] Prepreg skin: woven carbon fiber prepreg, resin content: 50wt%, molding processing temperature: 120℃;

[0066] (2) Preparation of thermally expandable resin sheet;

[0067] (2.1) 100 parts of epoxy resin by weight fraction were placed in a water bath at 90℃ for 20min;

[0068] (2.2) Stir at a speed of 300r / min until the viscosity remains unchanged for 10min;

[0069] (2.3) Reduce the stirring speed to 80r / min, and add 15 parts of curing agent, 3 parts of coupling agent, 3 parts of flame retardant, 2 parts of surfactant and 5 parts of thermally expandable microspheres to the epoxy resin by weight fraction while stirring;

[0070] (2.4) Increase the stirring speed to 600r / min and stir for 60min to obtain a mixed solution;

[0071] (2.5) The thermally expandable resin sheet is prepared from the mixed solution by using a prepreg device;

[0072] The final thermally expandable resin sheet has a thermal expansion pressure of 0.6MPa, and the absolute value of the difference between the molding processing temperature of the thermally expandable resin sheet and the molding processing temperature of the prepreg skin is 5℃;

[0073] (3) The thermally expandable resin sheet with a thickness of 1mm and the prepreg skin with a thickness of 0.15mm are alternately laminated to obtain a laminate with a 3-layer structure, from top to bottom, the prepreg skin, the thermally expandable resin sheet, and the prepreg skin;

[0074] (4) The laminated body obtained in step (3) is first placed in a mold for curing foaming treatment for 1 h, as shown in Figure 1 and then cooled to 15°C at 15°C, to obtain a foam sandwich composite material with sound insulation properties; wherein the temperature of the curing foaming treatment is 15°C higher than the minimum foaming temperature of the heat-expandable microspheres.

[0075] The compressive strength of the foam sandwich composite material with sound insulation properties finally prepared is 5.5 MPa, and the average sound insulation of the foam sandwich composite material with sound insulation properties at a frequency of 400-5000 Hz is 58 dB, as shown in Figure 2 .

[0076] Comparative Example 1

[0077] A method for preparing a foam sandwich composite material with sound insulation properties is basically the same as that of Example 1, except that the number of parts of the heat-expandable microspheres added in step (2.3) is 3 parts.

[0078] The heat-expandable resin sheet finally prepared has a heat expansion pressure of 0.3 MPa.

[0079] The compressive strength of the foam sandwich composite material with sound insulation properties finally prepared is 7 MPa, and the average sound insulation of the foam sandwich composite material with sound insulation properties at a frequency of 400-5000 Hz is 38 dB.

[0080] Comparing Comparative Example 1 with Example 1, it can be seen that the sound insulation performance of the composite material is poor due to the too small heat expansion pressure of the heat-expandable resin sheet prepared in step (2). On the one hand, the too small heat expansion pressure of the heat-expandable resin sheet leads to a small number of foam cells in the foam sandwich composite material and a small inner diameter of the formed foam cells. On the other hand, the too small heat expansion pressure of the heat-expandable resin sheet also affects the molding of the prepreg skin, resulting in many defects on the prepreg skin and poor sound insulation performance of the sandwich composite material.

[0081] Comparative Example 2

[0082] A method for preparing a foam sandwich composite material with sound insulation properties is basically the same as that of Example 1, except that the number of parts of the heat-expandable microspheres added in step (2.3) is 25 parts.

[0083] The heat-expandable resin sheet finally prepared has a heat expansion pressure of 1.8 MPa.

[0084] The compressive strength of the foam sandwich composite material with sound insulation properties finally prepared is 4.8 MPa, and the average sound insulation of the foam sandwich composite material with sound insulation properties at a frequency of 400-5000 Hz is 42 dB.

[0085] Comparative Example 2 and Example 1 can be compared, the thermal expansion pressure of the thermal expansion resin sheet prepared in step (2) in Comparative Example 2 is too large, resulting in low compressive strength and poor sound insulation performance of the foam sandwich composite material, because the thermal expansion pressure of the thermal expansion resin sheet is too large, the expanded microspheres inside the foam are expanded by heating and the volume is increased by more than 50 times, the wall of the expanded microspheres is thinned, resulting in low strength of the expanded microspheres, and a large number of expanded microspheres are accumulated together to generate a larger expansion force, a part of them is crushed to form a larger hole defect when they are extruded, and another part is extruded into the prepreg skin to form a defect of the prepreg skin, so that the dense structure on the surface of the prepreg skin is damaged, thereby reducing the ability to reflect and lose sound waves.

[0086] Comparative Example 3

[0087] A method for preparing a foam sandwich composite material with sound insulation performance, which is basically the same as Example 1, except that the thermal expansion microspheres prepared in step (1) are from Nanjing Saipu High Polymer Material Co., Ltd., the model number is 930DU20, and the forming processing temperature of the thermal expansion resin sheet is 145℃.

[0088] The thermal expansion pressure of the finally prepared thermal expansion resin sheet is 0.4MPa, and the absolute value of the difference between the forming processing temperature of the thermal expansion resin sheet and the forming processing temperature of the prepreg skin is 25℃.

[0089] The compressive strength of the finally prepared foam sandwich composite material with sound insulation performance is 5.1MPa, and the average sound insulation amount of the foam sandwich composite material with sound insulation performance at the same frequency in Example 1 is 38dB.

[0090] Comparative Example 3 and Example 1 can be compared, the absolute value of the difference between the forming processing temperature of the thermal expansion resin sheet and the forming processing temperature of the prepreg skin is too large, resulting in poor sound insulation performance of the foam sandwich composite material, because the forming processing temperature of the prepreg skin is significantly lower than the forming processing temperature of the thermal expansion resin sheet, the curing speed of the prepreg skin is faster than the curing speed of the thermal expansion resin sheet, the expansion force of the thermal expansion resin is small during the forming of the prepreg skin, the forming effect is not good, the reflection loss of sound waves is poor, and the interfacial bonding force between the prepreg skin and the thermal expansion resin is not good, which can cause the mechanical properties of the prepared foam sandwich composite material to deteriorate.

[0091] Comparative Example 4

[0092] A method for preparing a foam sandwich composite material with sound insulation performance, which is basically the same as Example 1, except that the temperature of the curing and foaming process in step (4) is 5℃ higher than the minimum foaming temperature of the thermal expansion microspheres.

[0093] The compressive strength of the foam sandwich composite material with sound insulation properties prepared finally was 6.5 MPa, and the average sound insulation of the foam sandwich composite material with sound insulation properties at the frequency of 400-5000 Hz was 45 dB.

[0094] It can be seen from the comparison between Comparative Example 4 and Example 1 that the temperature of the curing and foaming treatment and the minimum foaming temperature of the thermal expansion microspheres are too small, resulting in poor sound insulation performance of the foam sandwich composite material. This is because the temperature of the curing and foaming treatment is too low, resulting in small cell structure inside the foam and small expansion force of the foam, and the sound insulation performance of the prepared foam sandwich composite material is poor.

[0095] Comparative Example 5

[0096] A method for preparing a foam sandwich composite material with sound insulation properties, which is basically the same as Example 1, except that the temperature of the curing and foaming treatment in step (4) is 25°C higher than the minimum foaming temperature of the thermal expansion microspheres.

[0097] The compressive strength of the foam sandwich composite material with sound insulation properties prepared finally was 4 MPa, and the average sound insulation of the foam sandwich composite material with sound insulation properties at the frequency of 400-5000 Hz was 48 dB.

[0098] It can be seen from the comparison between Comparative Example 4 and Example 1 that the temperature of the curing and foaming treatment and the minimum foaming temperature of the thermal expansion microspheres are too large, resulting in poor sound insulation performance of the foam sandwich composite material. This is because the temperature of the curing and foaming treatment is too high, resulting in large cell diameter inside the foam sandwich composite material, and accompanied by breakage of part of the thermal expansion microspheres, forming large defects inside the foam sandwich composite material, and further affecting the sound insulation performance of the foam sandwich composite material.

[0099] Example 2

[0100] A method for preparing a foam sandwich composite material with sound insulation properties, the steps are as follows:

[0101] (1) Preparation of raw materials;

[0102] Epoxy resin: Nanya Epoxy Resin 901;

[0103] Curing agent: diethylene triamine;

[0104] Coupling agent: KH560;

[0105] Flame retardant: dimethyl methylphosphonate;

[0106] Surfactant: Tween 80;

[0107] Thermal expansion microspheres: the manufacturer is Nolikon Company, the brand is 051DU40, the minimum foaming temperature is 110℃, and the maximum foaming temperature is 130℃;

[0108] Prepreg skin: woven carbon fiber prepreg, the resin content is 50wt%, and the molding processing temperature is 120℃;

[0109] (2) preparing thermal expansion resin sheet;

[0110] (2.1) 100 parts of epoxy resin were placed in a water bath at 90℃ for 20 min;

[0111] (2.2) stirring at a stirring speed of 200r / min until the viscosity remains unchanged for 5 min;

[0112] (2.3) reducing the stirring speed to 60r / min, and adding 20 parts of curing agent, 5 parts of coupling agent, 3 parts of flame retardant, 2 parts of surfactant and 10 parts of thermal expansion microspheres into the epoxy resin while stirring;

[0113] (2.4) increasing the stirring speed to 500r / min and stirring for 60 min to obtain a mixed solution;

[0114] (2.5) preparing thermal expansion resin sheet from the mixed solution by using a prepreg device;

[0115] The thermal expansion pressure of the finally prepared thermal expansion resin sheet is 0.8MPa, and the absolute value of the difference between the molding processing temperature of the thermal expansion resin sheet and the molding processing temperature of the prepreg skin is 10℃;

[0116] (3) alternately stacking the thermal expansion resin sheet with a thickness of 2.5mm and the prepreg skin with a thickness of 0.5mm to obtain a laminate with a 3-layer structure, from top to bottom, the prepreg skin, the thermal expansion resin sheet, and the prepreg skin;

[0117] (4) placing the laminate obtained in step (3) in a mold for 2h of curing and foaming treatment, and then cooling to 20℃ at 20℃ to obtain a foam sandwich composite material with sound insulation characteristics; wherein the curing and foaming treatment temperature is 20℃ higher than the minimum foaming temperature of the thermal expansion microspheres.

[0118] The compressive strength of the finally prepared foam sandwich composite material with sound insulation characteristics is 7.5MPa, and the average sound insulation of the foam sandwich composite material with sound insulation characteristics at a frequency of 400-5000Hz is 53dB, as shown in Figure 2 .

[0119] Example 3

[0120] A method for preparing a foam sandwich composite material with sound insulation properties, substantially the same as embodiment 2, the difference is only that no flame retardant is added in step (3), and is replaced by the same weight fraction (same as embodiment 2) of epoxy resin.

[0121] The final prepared foam sandwich composite material with sound insulation properties has a compressive strength of 8 MPa, and the average sound insulation of the foam sandwich composite material with sound insulation properties at a frequency of 400-5000 Hz is 55 dB, as shown in Figure 2 .

[0122] Example 4

[0123] A method for preparing a foam sandwich composite material with sound insulation properties, the steps are as follows:

[0124] (1) Preparation of raw materials;

[0125] Epoxy resin: Nanya Epoxy Resin 901;

[0126] Curing agent: Diamino diphenyl sulfone;

[0127] Coupling agent: KH550;

[0128] Flame retardant: Hexabromobenzene;

[0129] Surfactant: Tween 80,

[0130] Thermally expandable microspheres: The manufacturer is Nolong Company, the model is 093DU120, the minimum foaming temperature is 120℃, and the maximum foaming temperature is 150℃;

[0131] Prepreg skin: unidirectional glass fiber prepreg, resin content is 40wt%, molding processing temperature is 130℃;

[0132] (2) Preparation of thermally expandable resin sheet;

[0133] (2.1) 100 parts of epoxy resin by weight fraction is placed in a water bath at 90℃ for 20min;

[0134] (2.2) Stir at a speed of 200r / min until the viscosity remains unchanged for 8min;

[0135] (2.3) Reduce the stirring speed to 50r / min, while stirring, add 10 parts of curing agent, 1 part of coupling agent, 10 parts of flame retardant, 1 part of surfactant and 10 parts of thermally expandable microspheres to the epoxy resin by weight fraction;

[0136] (2.4) Increase the stirring speed to 400r / min and stir for 60min to obtain a mixed solution;

[0137] (2.5) A thermally expandable resin sheet is prepared from the mixed solution using a prepreg device;

[0138] The final thermally expandable resin sheet has a thermal expansion pressure of 0.6 MPa, and an absolute value of the difference between the forming processing temperature of the thermally expandable resin sheet and the forming processing temperature of the prepreg skin is 10℃;

[0139] (3) A thermally expandable resin sheet with a thickness of 1 mm and a prepreg skin with a thickness of 0.1 mm are alternately laid to obtain a laminate with a 5-layer structure, from top to bottom in turn, prepreg skin, thermally expandable resin sheet, prepreg skin, thermally expandable resin sheet, prepreg skin;

[0140] (4) The laminate obtained in step (3) is first placed in a mold for 2h of curing and foaming treatment, and then cooled to 20℃ at 20℃ to obtain a foam sandwich composite material with sound insulation properties; wherein the curing and foaming treatment temperature is 15℃ higher than the minimum foaming temperature of the thermally expandable microspheres.

[0141] The final foam sandwich composite material with sound insulation properties has a compressive strength of 9 MPa, and the average sound insulation of the foam sandwich composite material with sound insulation properties at a frequency of 400-5000 Hz is 56dB, as shown in Figure 2 .

[0142] Example 5

[0143] A method for preparing a foam sandwich composite material with sound insulation properties, the steps are as follows:

[0144] (1) Preparation of raw materials;

[0145] Epoxy resin: Epoxy resin E-31;

[0146] Curing agent: Diamino diphenyl sulfone;

[0147] Coupling agent: KH550;

[0148] Flame retardant: Methyl phosphate dimethyl ester;

[0149] Surfactant: Tween 80;

[0150] Thermally expandable microspheres: The manufacturer is Nolane Company, the brand is 093DU120, the minimum foaming temperature is 120℃, and the maximum foaming temperature is 150℃;

[0151] Prepreg skin: Unidirectional glass fiber prepreg, resin content is 40wt%, forming processing temperature is 130℃;

[0152] (2) Preparation of thermally expandable resin sheet;

[0153] (2.1) By weight, 100 parts of epoxy resin were placed in a water bath and kept at 70°C for 30 minutes.

[0154] (2.2) Stir at a stirring speed of 200 r / min until the viscosity remains constant for 5 min;

[0155] (2.3) Reduce the stirring speed to 50 r / min, and add 10 parts of curing agent, 3 parts of coupling agent, 5 parts of flame retardant, 3 parts of surfactant and 10 parts of thermal expansion microspheres to the epoxy resin while stirring.

[0156] (2.4) Increase the stirring speed to 400 r / min and stir for 60 min to obtain a mixed solution;

[0157] (2.5) Thermally expandable resin sheets are prepared from a mixed solution using a prepreg equipment;

[0158] The final thermal expansion pressure of the thermal expansion resin sheet is 0.5 MPa, and the absolute value of the difference between the molding temperature of the thermal expansion resin sheet and the molding temperature of the prepreg skin is 20℃.

[0159] (3) A laminate with a 5-layer structure is obtained by alternately laying a 1mm thick thermal expansion resin sheet and a 0.1mm thick prepreg skin, which are arranged from top to bottom as prepreg skin, thermal expansion resin sheet, prepreg skin, thermal expansion resin sheet, and prepreg skin.

[0160] (4) The laminate obtained in step (3) is first placed in a mold for curing and foaming treatment for 2 hours, and then cooled to 30°C to obtain a foam sandwich composite material with sound insulation properties; wherein, the curing and foaming treatment temperature is 10°C higher than the minimum foaming temperature of the thermal expansion microspheres.

[0161] The final sound-insulating foam sandwich composite material has a compressive strength of 7 MPa and an average sound insulation of 50 dB at frequencies of 400-5000 Hz. Figure 2 As shown.

[0162] Example 6

[0163] A method for preparing a foam sandwich composite material with sound insulation properties is basically the same as in Example 5, except that: in step (1), aramid honeycomb paper (the side length of the cell of the honeycomb is 5mm) is prepared, and in step (3), the laminate is obtained by stacking thermally expanded resin sheet, prepreg skin and aramid honeycomb paper to obtain a laminate with a 5-layer structure, which is arranged from top to bottom as prepreg skin, thermally expanded resin sheet, aramid honeycomb paper, thermally expanded resin sheet and prepreg skin.

[0164] The compression strength of the foam sandwich composite material with sound insulation characteristics finally prepared is 12 MPa, and the average sound insulation of the foam sandwich composite material with sound insulation characteristics at a frequency of 400-5000 Hz is 70 dB, as shown in Figure 3 .

[0165] Example 7

[0166] A method for preparing a foam sandwich composite material with sound insulation characteristics, the steps are as follows:

[0167] (1) Preparation of raw materials;

[0168] Epoxy resin: Nanya Epoxy Resin 901;

[0169] Curing agent: Diamino diphenyl sulfone;

[0170] Coupling agent: KH550;

[0171] Flame retardant: Methyl dimethyl phosphate;

[0172] Surfactant: Tween 20;

[0173] Thermally expandable microspheres: The manufacturer is Nolane Company, the model is 093DU120, the minimum foaming temperature is 120℃, and the maximum foaming temperature is 150℃;

[0174] Prepreg skin: woven 3K carbon fiber prepreg, resin content is 50wt%, molding processing temperature is 120℃;

[0175] Aramid honeycomb paper: the side length of the honeycomb unit cell is 8mm;

[0176] (2) Preparation of thermally expandable resin sheet;

[0177] (2.1) 100 parts of epoxy resin by weight fraction is placed in a water bath at 70℃ for 30min;

[0178] (2.2) Stir at a speed of 250r / min until the viscosity remains unchanged for 8min;

[0179] (2.3) Reduce the stirring speed to 50r / min, and add 15 parts of curing agent, 3 parts of coupling agent, 3 parts of flame retardant, 3 parts of surfactant and 15 parts of thermally expandable microspheres to the epoxy resin by weight fraction while stirring;

[0180] (2.4) Increase the stirring speed to 600r / min and stir for 60min to obtain a mixed solution;

[0181] (2.5) The thermally expandable resin sheet is prepared from the mixed solution by using a prepreg device;

[0182] The thermal expansion resin sheet finally prepared has a thermal expansion pressure of 1 MPa, and an absolute value of a difference between a molding processing temperature of the thermal expansion resin sheet and a molding processing temperature of the prepreg skin is 10°C;

[0183] (3) A thermal expansion resin sheet with a thickness of 1.5 mm, a prepreg skin with a thickness of 0.15 mm, and aramid honeycomb paper with a thickness of 3 mm are laminated to obtain a laminate with a 7-layer structure, from top to bottom in turn, the prepreg skin, the thermal expansion resin sheet, the aramid honeycomb paper, the prepreg skin, the aramid honeycomb paper, the thermal expansion resin sheet, and the prepreg skin;

[0184] (4) The laminate obtained in step (3) is first placed in a mold for curing and foaming treatment for 1.5 h, and then cooled to 15°C at 15°C to obtain a foam sandwich composite material with sound insulation properties; wherein the curing and foaming treatment temperature is 20°C higher than the minimum foaming temperature of the thermal expansion microspheres.

[0185] The foam sandwich composite material finally prepared has a compressive strength of 15 MPa, and an average sound insulation of the foam sandwich composite material with sound insulation properties at a frequency of 400-5000 Hz is 75 dB, as shown in Figure 3 .

[0186] Example 8

[0187] A method for preparing a foam sandwich composite material with sound insulation properties, the steps are as follows:

[0188] (1) Preparation of raw materials;

[0189] Epoxy resin: epoxy resin E-42;

[0190] Curing agent: diethylene triamine;

[0191] Coupling agent: KH550;

[0192] Flame retardant: hexabromobenzene;

[0193] Surfactant: Tween 20;

[0194] Thermal expansion microspheres: the manufacturer is Nolane Company, the model is 093DU120, the minimum foaming temperature is 120°C, and the maximum foaming temperature is 150°C;

[0195] Prepreg skin: woven 3K carbon fiber prepreg, the resin content is 50wt%, and the molding processing temperature is 120°C;

[0196] Aramid honeycomb paper: the side length of the honeycomb cell is 10 mm;

[0197] (2) Preparation of thermal expansion resin sheet;

[0198] (2.1) 100 parts of the epoxy resin is placed in a water bath at 80℃ for 20 min;

[0199] (2.2) stirring at a speed of 300 r / min until the viscosity remains unchanged for 10 min;

[0200] (2.3) reducing the stirring speed to 50 r / min, and adding 15 parts of the curing agent, 3 parts of the coupling agent, 3 parts of the flame retardant, 3 parts of the surfactant and 10 parts of the thermal expansion microspheres into the epoxy resin while stirring;

[0201] (2.4) increasing the stirring speed to 600 r / min and stirring for 60 min to obtain a mixed solution;

[0202] (2.5) preparing a thermal expansion resin sheet from the mixed solution by using a prepreg device;

[0203] The thermal expansion pressure of the finally prepared thermal expansion resin sheet is 0.5 MPa, and the absolute value of the difference between the forming processing temperature of the thermal expansion resin sheet and the forming processing temperature of the prepreg skin is 10℃;

[0204] (3) laminating the thermal expansion resin sheet with a thickness of 1 mm, the prepreg skin with a thickness of 0.15 mm and the aramid honeycomb paper with a thickness of 5 mm to obtain a laminate with a 5-layer structure, from top to bottom in turn, the prepreg skin, the thermal expansion resin sheet, the aramid honeycomb paper, the thermal expansion resin sheet, and the prepreg skin;

[0205] (4) placing the laminate obtained in step (3) in a mold for curing and foaming treatment for 2 h, and then cooling to 25℃ at 25℃ to obtain a foam sandwich composite material with sound insulation properties; wherein the curing and foaming treatment temperature is 15℃ higher than the minimum foaming temperature of the thermal expansion microspheres.

[0206] The compressive strength of the finally prepared foam sandwich composite material with sound insulation properties is 11 MPa, and the average sound insulation of the foam sandwich composite material with sound insulation properties at a frequency of 400-5000 Hz is 73 dB, as shown in Figure 3 .

[0207] Example 9

[0208] A method for preparing a foam sandwich composite material with sound insulation properties, the steps are as follows:

[0209] (1) preparation of raw materials;

[0210] Epoxy resin: epoxy resin E-42;

[0211] Curing agent: diethylene triamine;

[0212] Coupling agent: KH560;

[0213] Flame retardant: dimethyl methylphosphonate;

[0214] Surfactant: Tween 20;

[0215] Thermally expandable microspheres: the manufacturer is Nolinge Company, the brand is 093DU120, the minimum foaming temperature is 120℃, and the maximum foaming temperature is 150℃;

[0216] Prepreg skin: unidirectional glass fiber prepreg, the resin content is 40wt%, and the forming processing temperature is 130℃;

[0217] Aramid honeycomb paper: the side length of the unit cell of the honeycomb is 10mm;

[0218] (2) Preparation of thermally expandable resin sheet;

[0219] (2.1) 100 parts of epoxy resin was placed in a water bath at 90℃ for 30min;

[0220] (2.2) Stirring at a speed of 200r / min until the viscosity remains unchanged for 5min;

[0221] (2.3) Reduce the stirring speed to 50r / min, and add 15 parts of curing agent, 3 parts of coupling agent, 5 parts of flame retardant, 2 parts of surfactant and 13 parts of thermally expandable microspheres to the epoxy resin while stirring;

[0222] (2.4) After increasing the stirring speed to 600r / min, stirring for 60min to obtain a mixed solution;

[0223] (2.5) The thermally expandable resin sheet was prepared from the mixed solution by using a prepreg equipment;

[0224] The final thermally expandable resin sheet has a thermal expansion pressure of 0.8MPa, and the absolute value of the difference between the forming processing temperature of the thermally expandable resin sheet and the forming processing temperature of the prepreg skin is 10℃;

[0225] (3) The thermally expandable resin sheet with a thickness of 3mm, the prepreg skin with a thickness of 0.1mm and the aramid honeycomb paper with a thickness of 15mm were laminated to obtain a laminate with a 4-layer structure, and the prepreg skin, the thermally expandable resin sheet, the aramid honeycomb paper and the prepreg skin were sequentially arranged from top to bottom;

[0226] (4) the laminated body obtained in step (3) is first placed in a mold for curing foaming treatment for 2 h, and then cooled to 25℃ at 25℃, to obtain a foam sandwich composite material with sound insulation properties; wherein the temperature of the curing foaming treatment is 15℃ higher than the minimum foaming temperature of the heat-expandable microspheres.

[0227] The compressive strength of the foam sandwich composite material with sound insulation properties finally prepared is 12 MPa, and the average sound insulation amount of the foam sandwich composite material with sound insulation properties at a frequency of 400-5000 Hz is 78 dB, as shown in Figure 3 .

[0228] Example 10

[0229] A method for preparing a foam sandwich composite material with sound insulation properties, the steps are as follows:

[0230] (1) Preparation of raw materials;

[0231] Epoxy resin: Nanya Epoxy Resin 901;

[0232] Curing agent: maleic anhydride;

[0233] Coupling agent: KH550;

[0234] Flame retardant: dimethyl methylphosphonate;

[0235] Surfactant: Tween 20;

[0236] Heat-expandable microspheres: the manufacturer is Nolane Company, the model is 051DU40, the minimum foaming temperature is 110℃, and the maximum foaming temperature is 130℃;

[0237] Prepreg skin: unidirectional glass fiber prepreg, the resin content is 40wt%, and the molding processing temperature is 130℃;

[0238] Aramid honeycomb paper: the side length of the honeycomb unit cell is 10mm;

[0239] (2) Preparation of heat-expandable resin sheet;

[0240] (2.1) 100 parts of epoxy resin by weight is placed in a water bath at 90℃ for 20 min;

[0241] (2.2) Stir at a stirring speed of 250 r / min until the viscosity remains unchanged for 8 min;

[0242] (2.3) Reduce the stirring speed to 50 r / min, and while stirring, add 10 parts of curing agent, 5 parts of coupling agent, 3 parts of flame retardant, 2 parts of surfactant and 13 parts of heat-expandable microspheres to the epoxy resin by weight;

[0243] (2.4) After the stirring speed is increased to 500 r / min, stirring is performed for 60 min to obtain a mixed solution;

[0244] (2.5) The mixed solution is used to prepare a thermally expandable resin sheet by using a prepreg device;

[0245] The thermal expansion pressure of the finally prepared thermally expandable resin sheet is 0.7 MPa, and the absolute value of the difference between the forming processing temperature of the thermally expandable resin sheet and the forming processing temperature of the prepreg skin is 10℃;

[0246] (3) A thermally expandable resin sheet with a thickness of 3 mm, a prepreg skin with a thickness of 0.1 mm, and aramid honeycomb paper with a thickness of 20 mm are laminated to obtain a laminate with a 4-layer structure, and the laminate is sequentially arranged from top to bottom as prepreg skin, thermally expandable resin sheet, aramid honeycomb paper, and prepreg skin;

[0247] (4) The laminate obtained in step (3) is first placed in a mold for 2 h of curing and foaming treatment, and then cooled to 25℃ at 25℃ to obtain a foam sandwich composite material with sound insulation properties; wherein the curing and foaming treatment temperature is 15℃ higher than the minimum foaming temperature of the thermally expandable microspheres.

[0248] The compressive strength of the finally prepared foam sandwich composite material with sound insulation properties is 13 MPa, and the average sound insulation of the foam sandwich composite material with sound insulation properties at a frequency of 400-5000 Hz is 80 dB, as shown in Figure 3 ​

Claims

1. A method of making a foam sandwich composite material having sound insulation properties, characterized in that, After the thermal expansion resin sheet is laid together with other sheets, it is first placed in a mold for curing and foaming, and then cooled to room temperature to obtain a foam sandwich composite material with sound insulation properties. The thermally expandable resin sheet is an epoxy resin sheet containing thermally expandable microspheres; other sheets are prepreg skins, or prepreg skins and aramid honeycomb paper. The thermal expansion pressure of the thermal expansion resin sheet is 0.5-1MPa; the absolute value of the difference between the molding temperature of the thermal expansion resin sheet and the molding temperature of the prepreg skin does not exceed 20℃; the curing and foaming temperature is 10-20℃ higher than the minimum foaming temperature of the thermal expansion microspheres. The components and their amounts used to prepare the thermally expandable resin sheet by weight are as follows: 100 parts epoxy resin, 10-20 parts curing agent, 5-15 parts thermally expandable microspheres, 1-5 parts coupling agent, 1-3 parts surfactant, and 0-10 parts flame retardant. The room temperature is 15-30℃.

2. The method of claim 1, wherein the method further comprises the step of: The epoxy resin used to prepare the thermally expandable resin sheet is either bisphenol A type epoxy resin or bisphenol F type epoxy resin. ​ 3. The method of claim 2, wherein the method further comprises the step of: The preparation process of thermally expandable resin sheets is as follows: ​ (1) Place the epoxy resin in a water bath and keep it at 70-90℃ for 20-30 minutes; (2) Stir at a stirring speed of 200-300 r / min until the viscosity remains unchanged for 5-10 min; (3) Reduce the stirring speed to 50-80 r / min, and add curing agent, coupling agent, surfactant and thermal expansion microspheres to the epoxy resin while stirring, or further add flame retardant; (4) Increase the stirring speed to 400-600 r / min and stir for 60 min to obtain a mixed solution; (5) The thermally expandable resin sheet is prepared from the mixed solution using a prepreg equipment.

4. The method of claim 1, wherein the method further comprises the step of: 5 applying a sound absorbing material to the foam core. The curing agent is an aliphatic polyamine curing agent, an aromatic polyamine, or an anhydride curing agent; The outer shell of the thermally expandable microspheres is made of thermoplastic resin, and the interior is filled with hydrocarbon gas that expands with heat. The minimum foaming temperature of the thermally expandable microspheres is 110-120℃, and the maximum foaming temperature is 130-150℃. The coupling agent is a silane coupling agent; The surfactant is a fatty acid surfactant or an aliphatic ester surfactant; The flame retardant is an organophosphate flame retardant or a bromine-containing aromatic flame retardant.

5. The method for preparing a foam sandwich composite material with sound insulation properties according to claim 1, characterized in that, The thickness of the thermally expanded resin sheet is 0.1-3mm; the prepreg skin is made of carbon fiber prepreg or glass fiber prepreg; the thickness of the prepreg skin is 0.1-0.15mm; the thickness of the aramid honeycomb paper is 3-20mm.

6. The method for preparing a foam sandwich composite material with sound insulation properties according to claim 1, characterized in that, When other sheets are prepreg skins, thermally expanded resin sheets and prepreg skins are laid alternately, with one more prepreg skin than thermally expanded resin sheet; when other sheets are prepreg skins and aramid honeycomb paper, each aramid honeycomb paper has at least one prepreg skin on each side.

7. The method for preparing a foam sandwich composite material with sound insulation properties according to claim 6, characterized in that, The laminate obtained by stacking has a 3-layer structure, from top to bottom: prepreg skin, thermally expanded resin sheet, and prepreg skin; Alternatively, the laminate obtained by stacking has a 5-layer structure, which from top to bottom consists of a prepreg skin, a thermally expanded resin sheet, a prepreg skin, a thermally expanded resin sheet, and a prepreg skin. Alternatively, the laminate obtained by stacking has a 4-layer structure, from top to bottom: prepreg skin, thermally expanded resin sheet, aramid honeycomb paper, and prepreg skin. Alternatively, the laminate obtained by stacking has a 5-layer structure, which from top to bottom consists of a prepreg skin, a thermally expanded resin sheet, an aramid honeycomb paper, a thermally expanded resin sheet, and a prepreg skin. Alternatively, the laminated structure has a 7-layer structure, consisting of, from top to bottom, a prepreg skin, a thermally expanded resin sheet, an aramid honeycomb paper, a prepreg skin, an aramid honeycomb paper, a thermally expanded resin sheet, and a prepreg skin.

8. The method for preparing a foam sandwich composite material with sound insulation properties according to claim 1, characterized in that, The curing and foaming process takes 1-2 hours.

9. The method for preparing a foam sandwich composite material with sound insulation properties according to claim 1, characterized in that, The compressive strength of the foam sandwich composite material with sound insulation properties is 5.5-15MPa, and the average sound insulation of the foam sandwich composite material with sound insulation properties is 50-80dB at a frequency of 400-5000Hz.

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