Sound matching layer for enhancing anti-interference capability, preparation method of sound matching layer and ultrasonic sensor

Abstract

The invention relates to the technical field of matching layer materials, and provides a sound matching layer capable of enhancing anti-interference capability, a preparation method of the sound matching layer and an ultrasonic sensor, the sound matching layer comprises the following components in parts by weight: 10-20 parts of modified hollow glass microspheres, 50-90 parts of epoxy resin, 15-30 parts of silicon dioxide nanoparticles, 10-20 parts of alumina powder and 1-5 parts of a curing agent; the preparation method comprises the following steps: heating the epoxy resin, adding the diluent and the curing agent, fully stirring, then adding the silicon dioxide nanoparticles, the alumina powder and the modified hollow glass microspheres, fully stirring, and heating to obtain the sound matching layer; the ultrasonic sensor comprises the sound matching layer. According to the preparation method, the compactness of the acoustic matching layer material can be improved, the low density and conductivity of the ultrasonic sensor can be met, the sensitivity and shielding effects of the ultrasonic sensor can be improved, and the sensitivity and anti-interference effects are improved.

Description

Technical Field

[0001] The invention relates to the technical field of matching layer materials, and in particular to an acoustic matching layer with enhanced anti-interference capability, a preparation method thereof, and an ultrasonic sensor. Background Art

[0002] The ultrasonic sensor is constructed by placing an acoustic matching layer with a certain acoustic impedance between the piezoelectric ceramic and the object to be detected, thereby improving the transmission efficiency of ultrasonic waves and improving the detection sensitivity. In an ultrasonic sensor used as a gas sensor, in order to improve the efficiency of ultrasonic transmission and reception, the acoustic matching layer is required to have a low density.

[0003] Therefore, the existing acoustic matching layer is generally mixed with epoxy resin and hollow glass microspheres as fillers, and is used as an acoustic matching layer after curing to adjust the reflection, absorption and diffusion characteristics of sound and improve the indoor sound environment; the density is generally required to be preferably 0.20-0.80g / cm 3 Therefore, fillers cannot add high-density conductive materials in order to reduce weight. However, if hollow glass microspheres are only blended with epoxy resin, the prepared acoustic matching layer has poor density, resulting in severe scattering and attenuation of ultrasonic waves in the air. Summary of the invention

[0004] Based on the above problems, the present invention is committed to improving the compatibility between hollow glass microspheres and epoxy resin to improve the compactness of the acoustic matching layer material; specifically, the present invention can effectively improve the compatibility between the matrix and the filler by surface modification of the hollow glass microspheres; therefore, the purpose of the present invention is to provide an acoustic matching layer with enhanced anti-interference ability, a preparation method thereof, and an ultrasonic sensor.

[0005] The embodiments of the present invention are achieved through the following technical solutions:

[0006] An acoustic matching layer with enhanced anti-interference capability comprises, by weight: 10-20 parts of modified hollow glass microspheres, 50-90 parts of epoxy resin, 15-30 parts of silicon dioxide nanoparticles, 10-20 parts of aluminum oxide powder, and 1-5 parts of a curing agent.

[0007] Furthermore, the modified hollow glass microspheres are amidation-modified hollow glass microspheres.

[0008] Furthermore, the method for preparing the modified hollow glass microspheres comprises the following steps:

[0009] 1) Hydroxylation hollow glass microspheres: Add nickel-plated hollow glass microspheres into an alkaline solution, wash the obtained suspension with deionized water, filter it, and dry it at 50-100° C. for 10-12 hours to obtain hydroxylation nickel-plated hollow glass microspheres;

[0010] 2) Amination of hollow glass microspheres: dissolving the hydroxylated hollow glass microspheres prepared in step 1) in an organic solvent, then adding polyethyleneimine and a coupling agent to attach amino groups to the surface of the hydroxylated hollow glass microspheres; washing the obtained mixture with deionized water and filtering it for 3 times, and drying it at 50-100° C. for 3-8 hours to obtain amination of nickel-plated hollow glass microspheres;

[0011] 3) Dissolve the aminated nickel-plated hollow glass microspheres and polymethyl methacrylate-polyamide copolymer obtained in step 2) in an organic solvent (such as dimethyl sulfoxide), and stir at 50-100°C for 1-5 hours, and a stable amide bond is formed between the aminated hollow glass microspheres and the polymethyl methacrylate-polyamide copolymer through an amidation reaction. The product is washed and filtered three times with an organic solvent (such as dimethyl sulfoxide) to remove residual monomers, and dried at 50-100°C for 10-12 hours to obtain modified hollow glass microspheres.

[0012] The invention first prepares hydroxylated hollow glass microspheres, then uses the hydroxyl groups on the hydroxylated hollow glass microspheres to react with a coupling agent, thereby reducing the hydroxyl groups, and reacts with polyethyleneimine containing a large number of amino groups, so that the amino groups are attached to the surface of the hydroxylated hollow glass microspheres, thereby obtaining aminated nickel-plated hollow glass microspheres, and finally uses polymethyl methacrylate-polyamide copolymers to be grafted onto the surface of the aminated nickel-plated hollow glass microspheres, and amidates the aminated nickel-plated hollow glass microspheres, wherein nitrogen atoms in the amide bonds form a conjugated structure with carbon atoms in the carbonyl groups through lone pairs of electrons, and the chemical bond stability is improved, thereby improving the binding energy; and after the polymethyl methacrylate-polyamide copolymers are grafted onto the surface of the hollow glass microspheres, the polymethyl methacrylate-polyamide copolymers can be extended outward from the surface of the hollow glass microspheres in a ring-forming or chain-forming manner, thereby forming an entanglement effect with a polymer chain segment in an epoxy resin matrix, thereby significantly improving the dispersibility of low-density hollow glass microspheres in a high-density epoxy resin matrix, thereby improving the compatibility between the hollow glass microspheres and the epoxy resin.

[0013] Furthermore, the coupling agent includes but is not limited to: a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, an organic coupling agent, and a polyamide coupling agent.

[0014] Furthermore, the curing agent is a phenolic amine epoxy curing agent, such as T-31 curing agent; or methyl hexahydrophthalic anhydride.

[0015] A method for preparing an acoustic matching layer with enhanced anti-interference capability comprises the following steps:

[0016] After the epoxy resin is heated (30-50°C) to improve the fluidity of the colloid, a diluent (such as acetone) and a curing agent (such as T-31 curing agent) are added and fully stirred, and then silica nanoparticles, alumina powder, and modified hollow glass microspheres are added and fully stirred, and heated at 50-100°C for 5-10h to allow the modified hollow glass microspheres to completely cross-link and polymerize with the epoxy; thus, an acoustic matching layer is obtained.

[0017] An ultrasonic sensor comprises the acoustic matching layer mentioned above.

[0018] The technical solution of the embodiment of the present invention has at least the following advantages and beneficial effects:

[0019] 1. After polymethyl methacrylate-polyamide copolymer is grafted on the surface of the aminated nickel-plated hollow glass microspheres, the present invention can extend outward from the surface of the hollow glass microspheres in a ring or chain manner, thereby forming an entanglement effect with the polymer chain segments in the epoxy resin matrix. Therefore, the dispersibility of low-density hollow glass microspheres in the high-density epoxy resin matrix can be significantly improved, thereby improving the compatibility between the hollow glass microspheres and the epoxy resin, and further improving the compactness of the acoustic matching layer material, which can not only meet the low density and conductivity of the ultrasonic sensor, but also play a role in improving the sensitivity and shielding of the ultrasonic sensor, and play a role in improving sensitivity and anti-interference. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0021] Example 1

[0022] An acoustic matching layer with enhanced anti-interference capability comprises, by weight: 15 parts of modified hollow glass microspheres, 70 parts of epoxy resin, 20 parts of silicon dioxide nanoparticles, 15 parts of alumina powder, and 3 parts of a curing agent; the modified hollow glass microspheres are amidation-modified hollow glass microspheres; specifically, the preparation method of the modified hollow glass microspheres comprises the following steps:

[0023] 1) Nickel-plated hollow glass microspheres: refer to the preparation method of nickel-plated glass microspheres disclosed in Example 1 of CN111763931A;

[0024] 2) Hydroxylation hollow glass microspheres: 10 g of nickel-plated hollow glass microspheres were added to 200 mL of 0.5 M sodium hydroxide solution, and the resulting suspension was washed with deionized water, filtered three times, and dried at 80° C. for 10 h to obtain hydroxylated nickel-plated hollow glass microspheres;

[0025] 3) Amination of hollow glass microspheres: 8 g of the hydroxylated hollow glass microspheres prepared in step 2) were dissolved in 200 mL of ethanol solvent, and then 5 g of polyethyleneimine and 1 g of a silane coupling agent were added. The obtained mixture was washed with deionized water, filtered 3 times, and dried at 80° C. for 5 h to obtain amination of nickel-plated hollow glass microspheres;

[0026] 4) Take 5 g of the aminated nickel-plated hollow glass microspheres prepared in step 3) and 5 g of polymethyl methacrylate-polyamide copolymer, dissolve them in dimethyl sulfoxide, and stir them at 70°C for 3 h. The product is washed with dimethyl sulfoxide, filtered 3 times, and dried at 70°C for 8 h to obtain modified hollow glass microspheres.

[0027] A method for preparing an acoustic matching layer with enhanced anti-interference capability comprises the following steps:

[0028] After the epoxy resin is heated to 40°C in a water bath, 500 mL of acetone and T-31 curing agent are added and stirred thoroughly, and then silica nanoparticles, alumina powder, and modified hollow glass microspheres are added and stirred thoroughly, and heated at 80°C for 6 hours to allow the modified hollow glass microspheres to completely cross-link and polymerize with the epoxy resin; thus, an acoustic matching layer is obtained.

[0029] An ultrasonic sensor comprises the acoustic matching layer mentioned above.

[0030] Example 2

[0031] The difference between this embodiment and embodiment 1 is that the acoustic matching layer for enhancing anti-interference capability comprises, by weight, 18 parts of modified hollow glass microspheres, 60 parts of epoxy resin, 25 parts of silicon dioxide nanoparticles, 13 parts of alumina powder, and 2 parts of curing agent.

[0032] Example 3

[0033] The difference between this embodiment and embodiment 1 is that the acoustic matching layer for enhancing anti-interference capability comprises, by weight, 14 parts of modified hollow glass microspheres, 65 parts of epoxy resin, 18 parts of silicon dioxide nanoparticles, 17 parts of alumina powder, and 4 parts of curing agent.

[0034] Example 4

[0035] The difference between this embodiment and embodiment 1 is that the acoustic matching layer for enhancing anti-interference capability comprises, by weight, 20 parts of modified hollow glass microspheres, 90 parts of epoxy resin, 15 parts of silicon dioxide nanoparticles, 10 parts of alumina powder, and 5 parts of curing agent.

[0036] Example 5

[0037] The difference between this embodiment and embodiment 1 is that the acoustic matching layer for enhancing anti-interference capability comprises, by weight, 10 parts of modified hollow glass microspheres, 50 parts of epoxy resin, 30 parts of silicon dioxide nanoparticles, 20 parts of alumina powder, and 1 part of curing agent.

[0038] Comparative Example 1

[0039] The difference between this comparative example and Example 1 is that the acoustic matching layer for enhancing anti-interference ability comprises, by weight, 5 parts of modified hollow glass microspheres, 100 parts of epoxy resin, 10 parts of silicon dioxide nanoparticles, 5 parts of alumina powder, and 10 parts of curing agent.

[0040] Comparative Example 2

[0041] The difference between this comparative example and Example 1 is that, by weight, it includes: 40 parts of modified hollow glass microspheres, 20 parts of epoxy resin, 40 parts of silicon dioxide nanoparticles, 5 parts of alumina powder, and 1 part of curing agent.

[0042] Comparative Example 3

[0043] The difference between this comparative example and Example 1 is that the hollow glass microspheres are not modified, that is, they are ordinary hollow glass microspheres.

[0044] Experimental Example 1

[0045] The main physical properties of the acoustic matching layer materials obtained in the above-mentioned Examples 1-3 and the comparative example were tested according to relevant testing standards. The test results are shown in Table 1:

[0046] Table 1 - Test results of different acoustic matching layer samples

[0047]

[0048] It can be seen from the data in Table 1 that the acoustic matching layer prepared by the present invention has higher mechanical properties, lower density and stronger anti-interference ability; while the mechanical properties, density and anti-interference ability of the acoustic matching layer prepared in Comparative Example 1 are relatively poor, mainly because the dosage ranges of the raw materials in Comparative Examples 1-2 are not within the range required by the embodiments of the present invention. It can be seen that under the synergistic effect of the raw materials and their dosage ratios of the present invention, the acoustic matching layer can achieve higher mechanical properties, lower density and stronger anti-interference ability; while in Comparative Example 3, mainly because the hollow glass microspheres have not been modified, the compatibility and dispersibility between them and the epoxy resin are poor, so the density of the material cannot meet the lower requirements, the anti-interference ability is weak, and the continuity in the stretching direction is poor, and it is easy to break, so the mechanical performance is not ideal compared with the embodiments;

[0049] In addition, since the hollow glass microspheres in the comparative example are not modified, they are easily destroyed during the processing, resulting in a lower resistivity. The data obtained by the comparative test are better than the data measured in the present application. The surface modification of the hollow glass microspheres can well maintain the original appearance of the hollow glass microspheres. After the polymethyl methacrylate-polyamide copolymer is grafted on the surface of the hollow glass microspheres, it can extend outward from the surface of the hollow glass microspheres in a ring or chain manner, thereby forming an entanglement effect with the polymer chain segments in the epoxy resin matrix. Therefore, the dispersibility of the low-density hollow glass microspheres in the high-density epoxy resin matrix can be significantly improved, thereby improving the compatibility between the hollow glass microspheres and the epoxy resin, making them uniformly dispersed in the epoxy resin matrix, and enhancing the compatibility with the epoxy resin. The hollow structure of the glass microspheres is used to effectively reduce the density of the epoxy resin, obtain a low-density acoustic matching layer material, and exhibit strong anti-interference ability, conductivity and shielding effect.

[0050] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An acoustic matching layer with enhanced anti-interference capability, characterized in that: Calculated by weight, the invention comprises: 10-20 parts of modified hollow glass microspheres, 50-90 parts of epoxy resin, 15-30 parts of silicon dioxide nanoparticles, 10-20 parts of aluminum oxide powder and 1-5 parts of curing agent.

2. The acoustic matching layer with enhanced anti-interference capability according to claim 1, characterized in that: Calculated by weight, the invention comprises: 15-20 parts of modified hollow glass microspheres, 60-90 parts of epoxy resin, 20-30 parts of silicon dioxide nanoparticles, 15-20 parts of aluminum oxide powder and 1-5 parts of curing agent.

3. The acoustic matching layer with enhanced anti-interference capability according to claim 1 or 2, characterized in that: The modified hollow glass microspheres are amidation-modified hollow glass microspheres.

4. The acoustic matching layer with enhanced anti-interference capability according to claim 3, characterized in that: The method for preparing the modified hollow glass microspheres comprises the following steps: 1) Hydroxylation hollow glass microspheres: Add nickel-plated hollow glass microspheres into an alkaline solution, wash the obtained suspension with deionized water, filter it, and dry it to obtain hydroxylation nickel-plated hollow glass microspheres; 2) Amination of hollow glass microspheres: dissolving the hydroxylated hollow glass microspheres prepared in step 1) in an organic solvent, then adding polyethyleneimine and a coupling agent to attach amino groups to the surfaces of the hydroxylated hollow glass microspheres; washing the obtained mixture with deionized water, filtering, and drying to obtain amination of nickel-plated hollow glass microspheres; 3) The aminated nickel-plated hollow glass microspheres and polymethyl methacrylate-polyamide copolymer prepared in step 2) are dissolved in an organic solvent. After a period of reaction, the product is washed with an organic solvent, filtered, and dried to obtain modified hollow glass microspheres.

5. The acoustic matching layer with enhanced anti-interference capability according to claim 4, characterized in that: The coupling agent includes any one or more of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, an organic coupling agent or a polyamide coupling agent.

6. The acoustic matching layer with enhanced anti-interference capability according to claim 4, characterized in that: The curing agent is a phenolic amine epoxy curing agent or methyl hexahydrophthalic anhydride.

7. A method for preparing an acoustic matching layer with enhanced anti-interference capability according to any one of claims 1 to 6, characterized in that: The following steps are involved: After the epoxy resin is heated, a diluent and a curing agent are added and fully stirred, and then silicon dioxide nanoparticles, alumina powder, and modified hollow glass microspheres are added and fully stirred, and the acoustic matching layer is obtained after heating.

8. An ultrasonic sensor, characterized in that: The acoustic matching layer comprises the acoustic matching layer according to any one of claims 1 to 6.

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