阅读说明：本技术 一种柔性透明机电耦合功能膜的制备方法 (Preparation method of flexible transparent electromechanical coupling functional film ) 是由 张晓青 阮泽海 于 2021-05-21 设计创作，主要内容包括：本发明涉及一种柔性透明机电耦合功能膜的制备方法,包括：通过聚合物树脂制备聚合物薄膜；采用网状模具,通过加压的方式,在预设的温度和压力下,经过一段时间将所述聚合物薄膜塑化并获得独特的一次微观结构；通过极化方式使得聚合物薄膜带电,并控制聚合物薄膜电荷稳定；将多个聚合物薄膜粘合,得到复合的聚合物薄膜即获得二次微观结构,对复合的聚合物薄膜的双面镀电极。与现有技术相比,本发明工艺过程简单,构思新颖,不仅能制备可控微结构的机电耦合功能膜,而且能够制备出具有高压电活性的机电耦合功能薄膜。(The invention relates to a preparation method of a flexible transparent electromechanical coupling functional film, which comprises the following steps: preparing a polymer film from a polymer resin; plasticizing the polymer film by a mesh mold in a pressurizing mode at a preset temperature and pressure for a period of time and obtaining a unique primary microstructure; the polymer film is charged through a polarization mode, and the charge stability of the polymer film is controlled; and adhering a plurality of polymer films to obtain a composite polymer film, namely obtaining a secondary microstructure, and plating electrodes on two sides of the composite polymer film. Compared with the prior art, the method has the advantages of simple process and novel concept, and can be used for preparing the electromechanical coupling functional film with the controllable microstructure and preparing the electromechanical coupling functional film with high piezoelectric activity.)

1. A preparation method of a flexible transparent electromechanical coupling functional film is characterized by comprising the following steps:

s1, preparing an initial polymer film through polymer resin;

s2, plasticizing the initial polymer film by a mesh mold in a pressurizing mode at a preset temperature and pressure for a period of time to obtain a primary microstructure, and obtaining a plasticized polymer film;

s3, electrifying the plasticized polymer film in a polarization mode, controlling the electric charge of the plasticized polymer film to be stable, then bonding a plurality of electrified polymer films to obtain a composite polymer film, namely a secondary microstructure, and finally plating electrodes on the two sides of the composite polymer film to obtain a final flexible transparent electromechanical coupling functional film;

or bonding a plurality of plasticized polymer films to obtain a composite polymer film, namely obtaining a secondary microstructure, plating electrodes on two sides of the composite polymer film, and finally, electrifying the polymer film plated with the electrodes in a polarization mode, and controlling the charge stability of the polymer film to obtain the final flexible transparent electromechanical coupling functional film.

2. The method as claimed in claim 1, wherein the polymer resin includes transparent polypropylene, fluorinated ethylene propylene copolymer, polyethylene, polycarbonate, cyclic olefin copolymer, etc.

3. The method for preparing a flexible transparent electromechanical coupling functional film according to claim 1, wherein the thickness of the polymer thin film is within a range of 100nm to 10 μm.

4. The method for preparing a flexible transparent electromechanical coupling functional film according to claim 1, wherein the plasticizing the initial polymer film specifically comprises the following steps:

and sequentially placing a stainless steel plate, a thick PTFE protective film, a thick rubber die, a polymer film and a reticular die, putting the stainless steel plate, the thick PTFE protective film, the thick rubber die, the polymer film and the reticular die into a hot press for preheating, then carrying out hot pressing treatment, and finally carrying out cold pressing treatment to obtain the plasticized polymer film with a regular microstructure.

5. The method for preparing a flexible transparent electromechanical coupling functional film according to claim 1, wherein the step of charging the polymer thin film by polarization comprises: the positive and negative voltage charging is respectively carried out on the two polymer films by a corona method, a soft X-ray method, a thermal polarization method, ion injection or a liquid contact method.

6. The method for preparing the flexible transparent electromechanical coupling functional film according to claim 5, wherein the corona method is used for respectively carrying out negative corona charging and positive corona charging on two polymer films through a corona charging electrode, and the corona charging electrode is needle-shaped, thread-shaped or knife-edge-shaped.

7. The method for preparing a flexible transparent electromechanical coupling functional film according to claim 1, wherein the bonding means comprises thermal bonding, ultrasonic bonding, laser bonding, and the like.

8. The method for preparing a flexible transparent electromechanical coupling functional film according to claim 1, wherein the polymer film is controlled to be stable in charge by heating or radiation.

9. The method for preparing a flexible transparent electromechanical coupling functional film according to claim 1, wherein the traces of adhesion comprise traces of adhesion forming rectangles with parallel adhesion or traces of adhesion with wavy lines.

10. The method for preparing a flexible transparent electromechanical coupling functional film according to claim 1, wherein the step S1 further comprises: pre-aging the initial polymer film.

Technical Field

The invention relates to the field of piezoelectric functional films, in particular to a preparation method of a flexible transparent electromechanical coupling functional film.

Background

The piezoelectric electret film which is characterized by a gas-solid binary phase structure and charge regular arrangement has a strong piezoelectric effect, and the piezoelectric coefficient d33 of the piezoelectric electret film is more than 20 times higher than that of a ferroelectric polymer PVDF; compared with piezoelectric ceramic materials, the piezoelectric electret has the advantages of higher piezoelectric coefficient d33, flexibility of polymer, large-area film forming, low cost, low relative dielectric constant, low acoustic impedance and the like. There has been considerable research progress in the development of piezoelectric electret films in wearable or skin-contact sensors for in vitro diagnostics. The robot has very good application potential in wider contact scenes of medical treatment and sports fitness, and is more remarkable in application of robot skin. The electronic skin touch sensor is very important wearable equipment and has very close connection with robots, medical equipment and human artificial limbs.

The flexible piezoelectric electret films reported in the literature are generally opaque or translucent and generally have a thickness greater than 70 microns. In some applications, a more transparent and thinner piezoelectric film is desired.

The common piezoelectric electret is opaque, so that the simulation of electronic skin is influenced, and the color of the skin can be adjusted by using the transparent electromechanical coupling functional film, so that the common piezoelectric electret is better close to the scene of practical application. In addition, in practical application of the robot skin, the thickness needs to be reduced as much as possible, and good elasticity is shown, so that the robot skin is not easy to damage in practical application, and the service life of the skin is prolonged. Physiologically, human skin has considerable complexity, and the spatial resolution of various parts of the human body is remarkably different, and the spatial resolution from fingertips, faces, toes and the like to thighs and abdomens is reduced from the highest to the lowest, for example, the spatial resolution of fingertips and abdomens is close to 1mm and more than 30mm, respectively, which requires the sensitivity of a film material applied to the skin of a robot to be able to recognize different degrees of contact force. This puts high demands on the piezoelectric activity of the piezoelectric film.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a preparation method of a flexible transparent electromechanical coupling functional film with strong piezoelectric activity.

The purpose of the invention can be realized by the following technical scheme:

a preparation method of a flexible transparent electromechanical coupling functional film comprises the following steps:

s1, preparing an initial polymer film through polymer resin;

s2, plasticizing the initial polymer film by a mesh mold in a pressurizing mode at a preset temperature and pressure for a period of time to obtain a primary microstructure, and obtaining a plasticized polymer film;

s3, electrifying the plasticized polymer film in a polarization mode, controlling the electric charge of the plasticized polymer film to be stable, then bonding a plurality of electrified polymer films to obtain a composite polymer film, namely a secondary microstructure, and finally plating electrodes on the two sides of the composite polymer film to obtain a final flexible transparent electromechanical coupling functional film;

or bonding a plurality of plasticized polymer films to obtain a composite polymer film, namely obtaining a secondary microstructure, plating electrodes on two sides of the composite polymer film, and finally, electrifying the polymer film plated with the electrodes in a polarization mode, and controlling the charge stability of the polymer film to obtain the final flexible transparent electromechanical coupling functional film.

Further, the polymer resin includes transparent polypropylene, fluorinated ethylene propylene copolymer, polyethylene, polycarbonate, cyclic olefin copolymer, and the like.

Further, the polymer thin film has a thickness within a range of 100nm to 10 μm.

Further, the plasticizing of the initial polymer film specifically comprises the steps of:

and sequentially placing a stainless steel plate, a thick PTFE protective film, a thick rubber die, a polymer film and a reticular die, putting the stainless steel plate, the thick PTFE protective film, the thick rubber die, the polymer film and the reticular die into a hot press for preheating, then carrying out hot pressing treatment, and finally carrying out cold pressing treatment to obtain the plasticized polymer film with a regular microstructure.

Further, the method for charging the polymer film by the polarization mode specifically comprises the following steps: the positive and negative voltage charging is respectively carried out on the two polymer films by a corona method, a soft X-ray method, a thermal polarization method, ion injection or a liquid contact method.

Further, the corona method is characterized in that negative corona charging and positive corona charging are respectively carried out on the two polymer films through a corona charging electrode, and the corona charging electrode is needle-shaped, filiform or knife-edge-shaped.

Further, the bonding means includes thermal bonding, ultrasonic bonding, laser bonding, and the like.

Further, the charge stability of the polymer film is controlled by heating or radiation.

Further, the trace of the bonding includes a bonding trace forming a rectangle by parallel bonding or a bonding trace by wavy lines, and the structure and the electromechanical coupling property of the transparent functional film are changed by controlling the distance of parallel lines of the bonding, the distance of wavy lines of the bonding and/or the curvature of wavy lines of the bonding.

Further, the step S1 further includes: pre-aging the initial polymer film.

Compared with the prior art, the invention has the following advantages:

(1) the invention has simple process and novel concept, not only can prepare the electromechanical coupling functional film with controllable microstructure, but also can prepare the film with high piezoelectric activity and d₃₃Thousands of high-performance electromechanical coupling functional films are achieved; and the film with high transparency and electromechanical coupling function can be prepared by PETDOT-PSS, thus greatly expanding the application prospect.

(2) The quasi-static longitudinal piezoelectric coefficient d33 of the flexible transparent electromechanical coupling functional film is as high as over 1000pC/N, is far higher than the piezoelectric activity of films in other researches, and the thickness of the film is far smaller than that of other piezoelectric electret films.

(3) The flexible transparent electromechanical coupling functional film has a specially designed microstructure, improves the transverse stretchability of the film to a certain extent, and is convenient for covering moving parts of complex equipment such as robot joints or medical equipment. Compared with other wearable flexible electronic devices, the efficiency continuity of the flexible transparent electromechanical coupling functional film can have a long service life when being used as robot skin, and the normal use of the robot is ensured. For example, the functional film obtained by using polypropylene after pre-aging and heat treatment has a life of 24 years.

Drawings

FIG. 1 is a schematic flow chart of a method for preparing a flexible transparent electromechanical coupling functional film according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a cross section of an electromechanical coupling functional thin film (polymer thin film);

FIG. 3 is a process diagram of the preparation of the PP electro-mechanical coupling functional film, wherein 1 is a rolling force, 2 is a PP film, and 3 is a polyester mesh mold;

FIG. 4 is a schematic cross-sectional view of a single PP film with primary microstructure and electromechanical coupling function;

FIG. 5 is a schematic cross-sectional view of a composite PP electromechanical coupling functional film obtained by bonding;

FIG. 6 is a schematic cross-sectional view of a secondary microstructure of the composite PP electromechanical coupling functional film.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

Referring to fig. 1, the present embodiment provides a method for preparing a flexible transparent electromechanical coupling functional film, including the following steps:

film preparation step S1: preparing a polymer film from a polymer resin;

the embodiment specifically includes: forming a film with the thickness of 100nm to 10 μm by using polymer resins such as transparent polypropylene, fluorinated ethylene propylene copolymer, polyethylene, polycarbonate, cyclic olefin copolymer and the like through processes such as melt extrusion stretching, blow molding, calendering, coating and the like;

film plasticizing step S2: plasticizing the polymer film for a period of time at a preset temperature and pressure by adopting a mesh mold in a pressurizing manner;

the embodiment specifically includes: the polymer film was hot and cold pressed using a PET web (mesh die) to give it a regular surface microstructure. The above operation was performed using a hot press. The polymer films were placed in the following order before treatment: stainless steel plate, thick PTFE protective film, thick rubber mold, PP film (polymer film), PET nethike embrane. Preheating the above samples in a hot press at a certain high temperature (T)₁) Hot pressing under a certain pressure (P), and then at a certain low temperature (T)₂) And performing cold pressing treatment under a certain pressure (P). A polymer film with a regular rectangular microstructure is obtained.

Film charging step S3: respectively carrying out positive voltage charging and negative voltage charging on the two polymer films in a polarization mode to enable the polymer films to be charged, and controlling the charge stability of the polymer films by a heating or radiation method; the polarization means include corona, soft X-ray, thermal polarization, ion implantation and liquid contact.

The corona method is characterized in that negative corona charging and positive corona charging are respectively carried out on two polymer films through a corona charging electrode, and the corona charging electrode is needle-shaped, filiform or knife-edge-shaped.

The working principle of corona charging is as follows: under a certain pressure and under the condition of constant voltage or constant current charging, the gas partial discharge between the electrodes, namely corona discharge, is caused by using a non-uniform electric field existing between the electrodes, ions generated by the corona discharge are deposited on the surface of the microporous structure membrane or perform charge exchange with the surface of the microporous structure membrane, so that a certain potential difference is generated between the upper surface and the lower surface of the microporous structure membrane, when the potential difference reaches or exceeds the discharge voltage of an air gap inside the microporous membrane, the internal gas discharge is caused, ions with opposite polarities generated by the discharge are deposited on the medium surface of an inner hole of the microporous structure membrane or perform charge exchange with the medium surface, and the upper wall and the lower wall of the inner hole are provided with charges with opposite polarities, so that the purpose of charging is achieved.

The embodiment specifically includes: and (3) taking two polymer films with secondary microstructures and subjected to the film plasticizing step, and respectively charging one surface of the film at a certain positive voltage and a certain negative voltage. Standing for a period of time until the charge is stabilized.

Film combining step S4: bonding a plurality of polymer films to obtain a composite polymer film; then plating electrodes on both sides of the composite polymer film;

the embodiment specifically includes: the two polymer films obtained were faced without corona polarization and were thermally bonded to give a series of fixed-pitch traces. The bond trace had both a four-sided closure and an unoccluded. The film may be bonded in various ways, such as thermal bonding, ultrasonic bonding, laser bonding, etc., which may have different effects on the piezoelectric activity of the film material.

The traces of adhesion include traces of adhesion forming rectangles in parallel adhesion or traces of adhesion in wavy lines, and the structure and piezoelectric properties of the transparent functional film are changed by controlling the distance of parallel lines of adhesion, the distance of wavy lines of adhesion, and/or the curvature of wavy lines of adhesion.

A flexible transparent electromechanical coupling functional film obtaining step: and sequentially executing the film preparation step, the film plasticizing step, the film charging step and the film combination step, or sequentially executing the film preparation step, the film plasticizing step, the film combination step and the film charging step, wherein the prepared polymer film is the final flexible transparent electromechanical coupling functional film.

The method comprises the steps of obtaining a plasticized polymer film through a film plasticizing step, enabling the plasticized polymer film to be charged through a polarization mode, controlling the charge stability of the plasticized polymer film, bonding a plurality of charged polymer films to obtain a composite polymer film, namely a secondary microstructure, and plating electrodes on two sides of the composite polymer film to obtain a final flexible transparent electromechanical coupling functional film;

or bonding a plurality of plasticized polymer films to obtain a composite polymer film, namely obtaining a secondary microstructure, plating electrodes on two sides of the composite polymer film, and finally, electrifying the polymer film plated with the electrodes in a polarization mode, and controlling the charge stability of the polymer film to obtain the final flexible transparent electromechanical coupling functional film.

The preparation method of the flexible transparent electromechanical coupling functional film can also equivalently comprise the following steps:

(1) forming a film with the thickness of 100nm to 10 μm by using polymer resins such as transparent polypropylene, fluorinated ethylene propylene copolymer, polyethylene, polycarbonate, cyclic olefin copolymer and the like through processes such as melt extrusion stretching, blow molding, calendering, coating and the like; (2) a reticular mould with characteristic structural parameters is adopted, and a film is plasticized to form a controllable microstructure (primary microstructure) in a pressurizing mode at a certain temperature (T) and a certain pressure (P) after a certain time (T); (3) adopting the polarization methods of corona, soft X-ray, thermal polarization, liquid contact and the like to charge the film; (4) stabilizing the charge by heating, irradiation and other methods; (5) combining and overlapping the polymer films in an effective manner, and giving a secondary microstructure (secondary microstructure) to the films by means of heat welding, ultrasonic welding, laser welding and the like; (6) and plating electrodes on both sides of the composite film to obtain the final transparent functional film.

The above-mentioned preparation steps (5) and (6) may be also adjusted in order before the step (3).

The proposed preparation conditions include, but are not limited to, the above temperature, pressure, film thickness, film combination overlapping manner, polarization voltage, primary microstructure, secondary microstructure, aging duration, plated electrode material, etc., and the specific conditions involved in the preparation process are adjusted within a reasonable range to suit the film preparation as a quasi-rope.

Structural characteristics of the transparent functional film: the surface of the single-layer polymer film is provided with a plurality of parallel indentations, so that a plurality of rectangles with the same size and shape are formed. After the two-layer polymer film is bonded, the surfaces of the two-layer polymer film have bonding traces with different intervals, and the bonding traces form a rectangular shape by parallel bonding or bonding traces with wavy lines.

The structure and electromechanical coupling performance of the transparent functional film are changed by controlling the distance of the parallel lines of the bonding, the distance of the wavy lines of the bonding and/or the curvature of the wavy lines of the bonding.

Different patterns of hot and cold pressing microstructures are given to the PP film by adjusting geometrical parameters of the mesh mold, such as wire diameter, mesh size and the like. The structure and electromechanical coupling performance of the transparent functional film are also changed by controlling different bonding modes, such as the distance of bonding parallel lines, the distance of bonding wavy lines, the curvature of bonding wavy lines and the like.

By adjusting the microstructure of the transparent functional film and controlling the polarization voltage, a very high piezoelectric activity can be obtained.

The thermal stability of the electromechanical coupling functional film can be further improved by pre-aging treatment.

Specifically, referring to fig. 2 to 6, the present embodiment employs a PP film having a thickness of 2 μm and a polyester mesh mold having a certain microstructure. Sequentially carrying out hot pressing and cold pressing, and controlling the temperature and the pressure of the cold and hot pressing to be proper (in the invention, the hot pressing adopts 90 ℃, the cold pressing adopts 10 ℃, the pressure adopts 2MPa, and other proper temperature and pressure can be controlled); the two films are charged at appropriate voltages (in the invention, the two films are charged at +10KV and-10 KV respectively). And standing the two PP composite films obtained by charging at normal temperature for about 24 hours, and plating transparent electrodes on the composite films obtained by thermal bonding after the charges are stable and reach an ideal surface potential to obtain the transparent functional films.

The foregoing detailed description of the preferred embodiments of the invention has been presented. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the present teachings without departing from the inventive concepts. Therefore, the technical solutions available to those skilled in the art through logic analysis, reasoning and limited experiments based on the prior art according to the concept of the present invention should be within the scope of protection defined by the claims.