阅读说明：本技术 一种lcp声学薄膜及其制备方法 (LCP acoustic film and preparation method thereof ) 是由 不公告发明人 于 2019-11-01 设计创作，主要内容包括：本发明提出了一种LCP声学薄膜,由以下原料制备而成：液晶聚合物、聚乳酸、纳米三氧化二铝、纳米碳酸钙、玄武岩、抗氧剂和复合偶联剂；所述液晶聚合物由如式Ⅰ和式Ⅱ所示液晶单体制备而成:<Image he="352" wi="700" file="DDA0002257017860000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>所述式Ⅰ结构通式中,n＝5-17；所述式Ⅱ结构通式中,R＝H,Cl,Br,I,CH<Sub>3</Sub>,CH<Sub>2</Sub>CH<Sub>3</Sub>,OCH<Sub>3</Sub>,COCH<Sub>3</Sub>,OCOCH3,Ph,Ar。本发明方法制备得的声学薄膜,表面光滑、稳定,具有很好的声学特性,在0.025Hz-25000Hz的声波频率范围内具有很好的响应度,灵敏度可达60-120mv/pa,静态压力灵敏度高达7um/pa。(The invention provides an LCP acoustic film which is prepared from the following raw materials: liquid crystal polymer, polylactic acid, nano aluminum oxide, nano calcium carbonate, basalt, antioxidant and composite coupling agent; the liquid crystal polymer is prepared from liquid crystal monomers shown in a formula I and a formula II: in the general structural formula of the formula I, n is 5-17; in the general structural formula of the formula II, R is H, Cl, Br, I, CH 3 ，CH 2 CH 3 ，OCH 3 ，COCH 3 OCOCH3, Ph, Ar. The acoustic film prepared by the method has smooth and stable surface and good acoustic characteristics, has good responsiveness in the acoustic frequency range of 0.025Hz-25000Hz, and has the sensitivity of 60-120mv/pa and the static pressure sensitivity of 7 um/pa.)

1. An LCP acoustic film is characterized by being prepared from the following raw materials: liquid crystal polymer, polylactic acid, nano aluminum oxide, nano calcium carbonate, basalt, antioxidant and composite coupling agent;

the liquid crystal polymer is prepared from liquid crystal monomers shown in a formula I and a formula II:

in the general structural formula of the formula I, n is 5-17;

in the general structural formula of the formula II, R is H, Cl, Br, I, CH₃，CH₂CH₃，OCH₃，COCH₃，OCOCH3，Ph，Ar；

The sensitivity of the LCP acoustic membrane in the sound wave frequency range of 0.025Hz-25000Hz is 60-120mv/pa, and the static pressure sensitivity is less than or equal to 7 um/pa.

2. The LCP acoustic film according to claim 1, which is prepared from the following raw materials in parts by weight: 100-120 parts of liquid crystal polymer, 5-12 parts of polylactic acid, 1-3 parts of antioxidant and 5-10 parts of composite coupling agent.

3. The LCP acoustic film according to claim 2, which is prepared from the following raw materials in parts by weight: 115 parts of liquid crystal polymer 105-polylactic acid, 6-10 parts of antioxidant and 6-9 parts of composite coupling agent.

4. The LCP acoustic film according to claim 3, which is prepared from the following raw materials in parts by weight: 110 parts of liquid crystal polymer, 9 parts of polylactic acid, 2.5 parts of antioxidant and 7 parts of composite coupling agent.

5. The LCP acoustic film of claim 1, wherein the liquid crystal polymer is prepared by a method comprising: and (2) filling the liquid crystal monomers shown in the formula I and the formula II and a catalyst into a liquid crystal box, adding a reaction solvent, and carrying out polymerization reaction at 70-80 ℃ under the protection of nitrogen to obtain the liquid crystal polymer.

6. The LCP acoustic membrane of claim 5, wherein the catalyst is selected from one or more of azobisisobutyronitrile, azobisisoheptonitrile, cyclohexanone peroxide, dibenzoyl peroxide, t-butyl hydroperoxide, and hexachloroplatinic acid.

7. The LCP acoustic film of claim 1, wherein the liquid crystal monomer of formula i is prepared by: dissolving polyethylene glycol in a solvent, slowly dropwise adding thionyl chloride in ice bath while stirring, continuously stirring for reacting for 2-3h after dropwise adding is finished, stopping the reaction, removing the solvent by rotary evaporation, washing with methanol, performing suction filtration, and drying to obtain the liquid crystal monomer shown in the formula I.

8. The LCP acoustic film of claim 1, wherein the liquid crystal monomer of formula ii is prepared by: dissolving vinyl alcohol in a solvent, slowly dropwise adding thionyl chloride in ice bath while stirring, continuously stirring for reacting for 2-3h after dropwise adding is finished, stopping the reaction, removing the solvent by rotary evaporation, washing with methanol to obtain a liquid, dissolving the liquid in the solvent, adding substituted 4-propenyloxyphenol and 4-dimethylaminopyridine, reacting for 1-3h after heating to 60 ℃, stopping the reaction, removing the solvent by rotary evaporation, washing with methanol, performing suction filtration, and drying to obtain the liquid crystal monomer shown in the formula II.

9. The LCP acoustic membrane according to claim 1, wherein the composite coupling agent comprises a composite of a silane coupling agent with amino groups and a common silane coupling agent with amino groups, the mass ratio of the common silane coupling agent to the silane coupling agent with amino groups is 5:2, the common silane coupling agent comprises one of KH550, KH560, KH570, KH792, DL602 and DL171, the antioxidant is selected from one or more of diphenylamine, p-phenylenediamine, dihydroquinoline, 2, 6-tertiary butyl-4-methylphenol, bis (3, 5-tertiary butyl-4-hydroxyphenyl) sulfide, tetra [ β - (3, 5-tertiary butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester, trioctyl ester, tridecyl ester, tris (dodecyl) ester or tris (hexadecyl) ester, and the lubricant is selected from one or more of silicone oil, fatty acid amide, oleic acid, polyester or synthetic ester, and the toughening agent is selected from one or more of carboxylated nitrile rubber, liquid vinyl butyral, polyether sulfone, or poly (cetyl alcohol) ketone.

10. A method of making an LCP acoustic membrane according to any one of claims 1 to 9, comprising the steps of:

s1, preparing a composite coupling agent into a dilute solution with the concentration of 0.2-0.4% to obtain a composite coupling agent solution;

s2, uniformly dispersing polylactic acid, nano aluminum oxide, nano calcium carbonate, basalt and an antioxidant in an ethanol water solution, dropwise adding a composite coupling agent solution while stirring, uniformly stirring, and irradiating for 30min by using ultraviolet light to obtain a mixed solution;

s3, dissolving the liquid crystal polymer in N, N-dimethylformamide solution, performing 100W ultrasonic dispersion for 30min, adding the mixed solution prepared in the step S2, stirring at the rotating speed of 300-500r/min for 30min, then immersing the tail end of the hollow stainless steel tube into the mixed solution for 3-7S until the outside of the hollow stainless steel tube is fully covered with the mixed solution, taking out until the hollow stainless steel tube, and curing by adopting ultraviolet irradiation to obtain the acoustic film.

Technical Field

The invention relates to the technical field of acoustic thin films, in particular to an LCP acoustic thin film and a preparation method thereof.

Background

The sound wave is a mechanical wave generated by the vibration of a sound source, the space for sound wave propagation is a sound field, and sound is a longitudinal wave when propagating in gas and liquid media, but may be mixed with a transverse wave when propagating in a solid medium. The frequency of the sound waves audible to the human ear is typically between 20Hz and 20000 Hz. Below 20Hz is infrasonic and above 20kHz is ultrasonic. The sound waves of different frequency bands have different purposes in the practical application process, and infrasound has important purposes in the aspects of ground sound exploration and ultrasound in the aspects of nondestructive testing, ultrasonic imaging and the like. When the sound waves are transmitted by the air, the density of the air is changed, and the air pressure is changed periodically; the effective method for detecting the sound wave is to convert sound vibration into an electric signal or an optical signal by utilizing the periodic change of the air pressure through the transduction of a film, and achieve the purpose of detecting the sound signal by detecting the electric signal or the optical signal; the common sound wave frequency detection means in the prior art is to use a capacitance type or piezoelectric type film for transduction, the weak pressure difference at two sides of the film is sensed by the film, the deformation of the film causes the change of the capacitance and the voltage of the film, and the change of the electric signal is consistent with the change of the sound signal; the capacitive or voltage type thin film requires that the thin film material has capacitance or piezoelectricity, the selectivity to the material is high, and the material cannot be used in the high magnetic field and high electromagnetic field.

In recent years, optical fiber microphones are widely researched, and particularly, partial performances of an acoustic sensing technology based on FP interference are equivalent to those of piezoelectricity or capacitance, and the optical fiber microphone has the characteristics of small volume, wide dynamic range, electromagnetic interference resistance, severe environment resistance and the like. The FP microphone film does not require piezoelectricity or capacitance, and various materials can be used for preparing acoustic films, such as silver films, silicon films, graphene films, polymer films, glycosyl films and the like; the sensitivity of an acoustic membrane is inversely proportional to the third power of the membrane thickness and directly proportional to the fourth power of the membrane radius; considering the size of the sensor, the thickness of the acoustic film is often smaller, and at the level of micron or even nanometer, the radius of the film is difficult to increase, the preparation process of the film is also complex, the cost is high, the low-frequency response is low, and the preparation of the acoustic film is a difficult point for the development of the acoustic sensor.

LCP plastic materials are called LIQUID CRYSTAL POLYMERs in the Chinese name. It is a novel polymer material which generally exhibits liquid crystallinity in a molten state. The material has excellent heat resistance and forming processing performance. The polymerization method mainly adopts melt polycondensation, and the wholly aromatic LCP is assisted by solid phase polycondensation to prepare a high molecular weight product. The non-aromatic LCP plastic raw material is usually prepared into a product by one-step or two-step melt polymerization. In recent years, techniques for preparing high molecular weight LCP by continuous melt polycondensation have been developed. The liquid crystal aromatic polyester has an abnormal regular fibrous structure, special performance and high product strength which are not inferior to metal and ceramic because macromolecular chains of the liquid crystal aromatic polyester are oriented in a liquid crystal state. Various thermoplastic engineering plastics have been developed for over 10 years. Good mechanical property, dimensional stability, optical property, electrical property, chemical resistance, flame retardance, processability, good heat resistance and lower thermal expansion coefficient. The performance, the processability and the price of the prepared liquid crystal polyester are different due to different monomers. The properties are also affected by the choice of filler and the amount of filler added.

Disclosure of Invention

In order to solve the technical problems, the invention provides an LCP acoustic film and a preparation method thereof, and aims to provide the LCP acoustic film, wherein the LCP material is modified by polylactic acid, nano aluminum oxide, nano calcium carbonate and basalt, so that the prepared liquid crystal polymer has better mechanical property, and still has excellent toughness in an ultrathin film material.

The invention provides an LCP acoustic film which is prepared from the following raw materials: liquid crystal polymer, polylactic acid, nano aluminum oxide, nano calcium carbonate, basalt, antioxidant and composite coupling agent;

the liquid crystal polymer is prepared from liquid crystal monomers shown in a formula I and a formula II:

in the general structural formula of the formula I, n is 5-17;

in the general structural formula of the formula II, R is H, Cl, Br, I, CH₃，CH₂CH₃，OCH₃，COCH₃，OCOCH3，Ph，Ar。

As a further improvement of the invention, the health-care food is prepared from the following raw materials in parts by weight: 100-120 parts of liquid crystal polymer, 5-12 parts of polylactic acid, 1-3 parts of antioxidant and 5-10 parts of composite coupling agent.

As a further improvement of the invention, the health-care food is prepared from the following raw materials in parts by weight: 115 parts of liquid crystal polymer 105-polylactic acid, 6-10 parts of antioxidant and 6-9 parts of composite coupling agent.

As a further improvement of the invention, the health-care food is prepared from the following raw materials in parts by weight: 110 parts of liquid crystal polymer, 9 parts of polylactic acid, 2.5 parts of antioxidant and 7 parts of composite coupling agent.

As a further improvement of the invention, the liquid crystal polymer is prepared by the following method: filling the liquid crystal monomers shown in the formula I and the formula II and a catalyst into a liquid crystal box, adding a reaction solvent, and carrying out polymerization reaction at 70-80 ℃ under the protection of nitrogen to obtain a liquid crystal polymer;

the mass fraction ratio of the monomer shown in the formula I, the monomer shown in the formula II and the catalyst is (20-50): (35-55): (1-3);

as a further improvement of the invention, the catalyst is selected from one or a mixture of a plurality of azodiisobutyronitrile, azodiisoheptonitrile, cyclohexanone peroxide, dibenzoyl peroxide, tert-butyl hydroperoxide and hexachloroplatinic acid.

The reaction solvent is one or a mixture of carbon tetrachloride, acetonitrile, pyridine, toluene, benzene, acetone, ethanol, methanol, N-dimethylformamide and tetrahydrofuran.

As a further improvement of the invention, the liquid crystal monomer shown in the formula I is prepared by the following method: dissolving polyethylene glycol in a solvent, slowly dropwise adding thionyl chloride in ice bath while stirring, continuously stirring for reacting for 2-3h after dropwise adding is finished, stopping the reaction, removing the solvent by rotary evaporation, washing with methanol, performing suction filtration, and drying to obtain a liquid crystal monomer shown in a formula I;

the mass ratio of the polyethylene glycol to the thionyl chloride is 1: 2.2.

as a further improvement of the invention, the liquid crystal monomer shown in the formula II is prepared by the following method: dissolving vinyl alcohol in a solvent, slowly dropwise adding thionyl chloride in ice bath while stirring, continuously stirring for reacting for 2-3h after dropwise adding is finished, stopping the reaction, removing the solvent by rotary evaporation, washing with methanol to obtain a liquid, dissolving the liquid in the solvent, adding substituted 4-propenyloxyphenol and 4-dimethylaminopyridine, reacting for 1-3h after heating to 60 ℃, stopping the reaction, removing the solvent by rotary evaporation, washing with methanol, performing suction filtration, and drying to obtain a liquid crystal monomer shown in a formula II;

the mass ratio of the vinyl alcohol to the thionyl chloride to the substituted 4-propenyloxyphenol to the 4-dimethylaminopyridine is 1:1.2:0.9: 0.01;

the solvent is one or a mixture of carbon tetrachloride, acetonitrile, pyridine, toluene, benzene, acetone, ethanol, methanol, N-dimethylformamide and tetrahydrofuran.

As a further improvement of the invention, the composite coupling agent comprises a common silane coupling agent and a silane coupling agent with amino groups, the mass ratio of the common silane coupling agent to the silane coupling agent with amino groups is 5:2, the common silane coupling agent comprises one of KH550, KH560, KH570, KH792, DL602 and DL171, the antioxidant is selected from one or a mixture of more of diphenylamine, p-phenylenediamine, dihydroquinoline, 2, 6-tertiary butyl-4-methylphenol, bis (3, 5-tertiary butyl-4-hydroxyphenyl) thioether, tetrakis [ β - (3, 5-tertiary butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester, trioctyl, tridecyl ester, tris (dodecanol) ester or tris (hexadecanol) ester, the lubricant is selected from one or a mixture of more of silicone oil, fatty acid amide, oleic acid, polyester or synthetic ester, and the toughening agent is selected from one or a mixture of more of carboxyl nitrile rubber, liquid nitrile rubber, polyvinyl butyral, polyether sulfone, and carboxyl polyether sulfone.

The invention further provides a preparation method of the LCP acoustic film, which comprises the following steps:

s1, preparing a composite coupling agent into a dilute solution with the concentration of 0.2-0.4% to obtain a composite coupling agent solution;

s2, uniformly dispersing polylactic acid, nano aluminum oxide, nano calcium carbonate, basalt and an antioxidant in an ethanol water solution, dropwise adding a composite coupling agent solution while stirring, uniformly stirring, and irradiating for 30min by using ultraviolet light to obtain a mixed solution;

s3, dissolving the liquid crystal polymer in N, N-dimethylformamide solution, performing 100W ultrasonic dispersion for 30min, adding the mixed solution prepared in the step S2, stirring at the rotating speed of 300-500r/min for 30min, then immersing the tail end of the hollow stainless steel tube into the mixed solution for 3-7S until the outside of the hollow stainless steel tube is fully covered with the mixed solution, taking out until the hollow stainless steel tube, and curing by adopting ultraviolet irradiation to obtain the acoustic film.

The antioxidant is selected from one or a mixture of more of diphenylamine, p-phenylenediamine, dihydroquinoline, 2, 6-tertiary butyl-4-methylphenol, bis (3, 5-tertiary butyl-4-hydroxyphenyl) thioether, pentaerythrityl tetrakis [ β - (3, 5-tertiary butyl-4-hydroxyphenyl) propionate ], trioctyl ester, tridecyl ester, tridodecyl alcohol ester or trihexadecyl alcohol ester.

The invention has the following beneficial effects:

the LCP material prepared by the invention has the advantages that the local vibration generated by the action of soft and hard phase media in the most main absorption form of a rigid structure benzene ring and a flexible chain polyethylene glycol chain is weakly coupled with a sound wave radiation mode, the LCP material has good acoustic characteristics and high sensitivity; polylactic acid, nano aluminum oxide, nano calcium carbonate and basalt are adopted to modify the LCP material, so that the prepared liquid crystal polymer has better mechanical property and still has excellent toughness in an ultrathin film material;

according to the invention, two different silane modifiers are compounded to modify different particles, wherein one silane modifier with hydroxyl helps inorganic particles with oxygen on the surface to be in modified linkage with LCP, a silane coupling agent with double bonds helps organic particles such as polyformaldehyde and the like to be in modified linkage with LCP, and the modified particles and LCP materials are chemically bonded through the compounded silane coupling agent to prepare LCP particles with better toughness and mechanical properties for later-stage preparation of LCP sound film materials;

the acoustic film prepared by the method has smooth and stable surface, the diameter is 1.52mm-2.70mm, and the thickness is 3.2 mu m-7.5 mu m; the diameter of the pressure sensor is larger than the thickness of the pressure sensor, the pressure sensor has good acoustic characteristics, good responsiveness in the sound wave frequency range of 0.025Hz-25000Hz, sensitivity of 60-120mv/pa and static pressure sensitivity of 7 um/pa.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, and it is obvious that the embodiments described are only some representative embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.