A piezoelectric article capable of positioning a pressure position and a preparation method thereof

Abstract

The present invention provides a piezoelectric article capable of positioning a pressure position and a preparation method thereof. In this preparation method, a high-voltage piezoelectric ceramic powder and a low-viscosity polymer powder are mixed and kneaded, and then pulverized to obtain a piezoelectric ceramic / low-viscosity polymer composite powder. After mixing it with a thermoplastic-processable high-viscosity polymer ultrafine powder, it is thermally cured and molded under the condition that the mold has a certain inclined length and an inclined angle, thus obtaining the piezoelectric article capable of positioning the pressure position. Through the gradient distribution density of the piezoelectric ceramic during the preparation process of this piezoelectric material, large strain is induced by stress concentration on the basis of the material maintaining the same thickness, realizing the function that the piezoelectric article can position the pressure position through the change of piezoelectric performance. At the same time, it has the characteristics of simple preparation and low cost. The prepared piezoelectric article can reach a maximum piezoelectric output of 60V and the thickness does not exceed 1 cm. This function can be applied to fields such as pipeline engineering and wearable devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of piezoelectric materials, and relates to a piezoelectric product capable of positioning a pressure position and a preparation method thereof, in particular to a piezoelectric product capable of positioning a pressure position based on a gradient change in piezoelectric output and a preparation method thereof. Background Art

[0002] The rapid development of artificial intelligence and mobile electronic technologies has promoted the continuous improvement of semiconductor manufacturing technologies and the continuous expansion of functions, thereby improving energy efficiency, reducing device size, and driving technological progress in the development of small electronic products. Currently, there are many methods for converting mechanical energy generated by vibrating or moving objects into electrical energy, including electromagnetic, electrostatic, and piezoelectric effects. Due to the high energy conversion efficiency and strong piezoelectric sensitivity of piezoelectric materials, they have been widely developed.

[0003] Piezoelectric materials can directly convert the applied mechanical stress into usable electrical energy and can be easily integrated into a system. As a widely used matrix material, polymers have advantages such as strong mechanical properties and long service life. By filling piezoelectric materials with good piezoelectric properties, such as piezoelectric ceramics, into the polymer substrate, the network structure of the polymer itself is changed, resulting in a significant increase in the piezoelectric properties of the composite material. Since piezoelectric ceramics are very sensitive to the action of the force field, the piezoelectric properties of this polymer composite material will change continuously under the action of the external force field. At the same time, due to the high elasticity of the polymer, it can provide great potential for flexible wearable piezoelectric devices.

[0004] However, for such piezoelectric materials, when applied to wearable piezoelectric devices, based on their piezoelectric application principle, it is only possible to judge whether they are stressed and the magnitude of the stress (equivalent to a conventional pressure sensor) through piezoelectric output, but it is impossible to judge the stress position / pressure position, thus making the current wearable piezoelectric devices have strong limitations in function expansion.

[0005] To solve the above problems, in the prior art, an array arrangement is mostly adopted through pressure sensors composed of such piezoelectric materials. When a force acts on a single or several pressure sensors in the array to output electrical signals, while the other pressure sensors in the array that are not subjected to the force do not output electrical signals, so as to judge the stress position / pressure position. For example, in the Chinese utility model patent "An electronic skin system based on the piezoelectric principle" (CN210862995U), the above technical method is used to judge the acting position of the force.

[0006] However, it is obvious that the accuracy of judging the pressure position in the above-mentioned existing technologies depends greatly on the size and the number of arrays of the pressure sensors. At the same time, a signal processing module capable of corresponding to multiple sensors and calculating responses in a timely manner is also required, which will undoubtedly greatly increase the cost of such wearable piezoelectric devices. Moreover, it is quite difficult to balance the circuit design, component layout and durability, which undoubtedly hinders the industrial practicalization process of such devices.

[0007] Therefore, based on the high elasticity of polymers, is it possible to maintain the function of a polymer-based piezoelectric material as an integral functional part in a wearable piezoelectric device while also having the function of positioning the pressure position, which will greatly promote the further development of related technologies. Summary of the Invention

[0008] In order to solve the problems in the above-mentioned existing technologies, the present invention provides a piezoelectric article capable of positioning the pressure position and a preparation method thereof. Through the gradient distribution density of piezoelectric ceramics in the preparation process of the piezoelectric material, large strain is induced by stress concentration on the basis of maintaining the same thickness of the material, realizing the function that the piezoelectric article can position the pressure position through the change of piezoelectric performance. At the same time, it has the characteristics of simple preparation and low cost. The highest piezoelectric output of the prepared piezoelectric article can reach 60V, and the thickness does not exceed 1 cm. This function can be applied to fields such as pipeline engineering and wearable devices.

[0009] To achieve the above object, the present invention adopts a technical solution composed of the following technical measures.

[0010] On the one hand, the present invention provides a preparation method of a piezoelectric article capable of positioning the pressure position, which includes the following steps by weight parts:

[0011] (1) Prepare piezoelectric ceramic powder with an average particle size of 0.1 - 500 μm and high piezoelectricity.

[0012] (2) Mix and knead 100 parts of piezoelectric ceramic powder with high piezoelectricity and 5 - 50 parts of low-viscosity polymer powder to obtain a piezoelectric ceramic / low-viscosity polymer composite material. Among them, the process parameters of the kneading treatment are: kneading time 3 - 20 minutes, rotation speed 10 - 50 revolutions per minute, and kneading temperature 90 - 150 °C;

[0013] Among them, the low-viscosity polymer selects a polymer with a viscosity of 10 - 500 CPS (140 °C);

[0014] (3) Crush the piezoelectric ceramic / low-viscosity polymer composite material obtained in step (2) to obtain a piezoelectric ceramic / low-viscosity polymer composite powder with an average particle size not lower than that of the piezoelectric ceramic powder with high piezoelectricity and not higher than 600 μm.

[0015] (4) the piezoelectric ceramic / low-viscosity polymer composite powder obtained in step (3) and the high-viscosity polymer ultrafine powder for thermoplastic processing are fully mixed in a mass ratio of 1:(0.5-3), added to a mold, and the mold is placed under a condition where the tilt angle is 0.5° to 20° relative to the horizontal plane and thermally cured and molded, and the tilt length of the mold is not less than 20 mm and the thickness is not more than 1 cm, so as to obtain a piezoelectric product capable of positioning the pressure position;

[0016] The ultrafine high-viscosity polymer powder for thermoplastic processing is selected from polymers with a viscosity of 500 to 1000 CPS (140° C.).

[0017] The inventive principle of the present invention is to develop a compression-shear coupling compression molding experimental equipment by adopting the rheological principle of polymer processing. By setting the inclination angle of the mold compared to the horizontal plane, when the piezoelectric ceramic / low-viscosity polymer composite powder is subjected to compressive stress, the stress is perpendicular to the contact surface, and the object produces compressive strain. At this time, the strain rate of each point in the surface is the same; when subjected to shear, the stress is parallel to the force-bearing surface, and the maximum shear strain is produced at the near force-bearing point, while the shear strain at the far force-bearing point is zero. The polymer melt is deformed in the direction of the shear force, generating a compression-shear coupling force field, so that the piezoelectric ceramic particles are enriched along the direction of the shear force field with the low-viscosity polymer, forming a gradient concentration in the surface along the shear direction. The prepared piezoelectric product can achieve different piezoelectric outputs at different positions, thereby judging the position of the stress point.

[0018] On this basis, the inventors of the present invention also found that the directional flow enrichment of piezoelectric ceramic particles can be enhanced by further limiting the mold inclination angle and the thermal curing molding process conditions, thereby preparing a piezoelectric product with high voltage output in a designated area and only low piezoelectric output in a non-designated area. That is, a piezoelectric product with two piezoelectric performance distribution areas on the same overall piezoelectric material is prepared, which facilitates functional expansion in subsequent applications.

[0019] In this article, the high-voltage piezoelectric ceramic powder in step (1) is a high-conductivity raw material known in the art, mainly including barium titanate, lead zirconate titanate, metaniobate and their composite systems. In one of the technical solutions, barium titanate or a barium titanate system is preferred for cost and environmental considerations.

[0020] In one technical solution, the high-voltage piezoelectric ceramic powder in step (1) can be selected from commercially available powders with an average particle size of 0.1 to 500 μm, or can be crushed into piezoelectric ceramic micro-nano powders with an average particle size of 0.1 to 500 μm. If necessary, the material preparation process also includes pretreatments such as washing and drying in the prior art.

[0021] It should be noted that in step (2), the high-voltage piezoelectric ceramic powder and the low-viscosity polymer powder are first prepared into a piezoelectric ceramic / low-viscosity polymer composite by internal mixing in order to first wrap the high-voltage piezoelectric ceramic powder with the low-viscosity polymer, so that it has certain mechanical properties, and at the same time improve the interfacial compatibility and fluidity between the high-voltage piezoelectric ceramic and the polymer added subsequently, so that it can flow and concentrate in the direction of the shear force field during thermosetting molding under inclined conditions.

[0022] In this article, the low-viscosity polymer described in step (2) is a polymer with a viscosity of 10-500 CPS (under the condition of 140 °C). Those skilled in the art can select a suitable conventional low-viscosity polymer according to the above condition limitations. To better illustrate the present invention and provide a reference technical solution, the low-viscosity polymer is preferably polyethylene wax powder, solid paraffin powder, etc.

[0023] In one preferred technical solution, the low-viscosity polymer powder in step (2) is preferably polyethylene wax powder. Generally speaking, the polyvinyl alcohol is commercially available, and the grade of the polyethylene wax is RLC-657.

[0024] In this article, the particle size of the low-viscosity polymer powder in step (2) can usually be selected to be the same as that of the high-voltage piezoelectric ceramic powder, or a commercially available low-viscosity polymer powder with a particle size of 0.1-500 μm or a mesh number of 100-2000 meshes can be selected to ensure the uniform distribution of the high-voltage piezoelectric ceramic.

[0025] It should be noted that the addition amount of the low-viscosity polymer powder in step (2) is limited to 5-50 parts, because if the addition amount of the low-viscosity polymer is too low, the adhesion between the high-voltage piezoelectric ceramic powder and the low-viscosity polymer itself will be low, and the interfacial interaction with the polymer substrate added subsequently will be poor; if the addition amount of the low-viscosity polymer is too high, the concentration of the high-voltage piezoelectric ceramic powder will be reduced, thus affecting the size of the piezoelectric performance gradient difference of the final product. During the actual operation process, the specific ratio of the low-viscosity polymer powder to the high-voltage piezoelectric ceramic powder can be reasonably adjusted according to the requirement of the piezoelectric performance gradient difference to obtain the required piezoelectric product. Preferably, the addition amount of the low-viscosity polymer powder is 10-30 parts.

[0026] In one of the technical solutions, the piezoelectric ceramic / low-viscosity polymer composite powder obtained by crushing the piezoelectric ceramic / low-viscosity polymer composite in step (3) has an average particle size not lower than that of the high piezoelectricity piezoelectric ceramic powder and not higher than 600 μm. The crushing treatment method of the high piezoelectricity piezoelectric ceramic powder described above can be similarly referred to. To better illustrate the present invention and provide a reference technical solution: the crushing treatment is carried out by a high-speed crusher. Among them, the process parameters of the high-speed crusher crushing treatment are: temperature 5 - 30 °C, rotation speed 200 - 400 revolutions per minute, and cyclic grinding 1 - 9 times.

[0027] In one of the technical solutions, the high-viscosity polymer ultrafine powder for thermoplastic processing described in step (4) is generally a polymer ultrafine powder that can be thermoplastically processed in the prior art and has a viscosity of 500 - 1000 CPS (under the condition of 140 °C). The selection includes LDPE ultrafine powder, PA11 ultrafine powder, PVDF ultrafine powder, etc.

[0028] In this article, the high-viscosity polymer ultrafine powder for thermoplastic processing described in step (4) is crushed to a particle size of 50 - 500 μm, or a commercially available high-viscosity polymer ultrafine powder with a particle size of 50 - 500 μm or a mesh number of 30 - 300 is selected.

[0029] It is worth emphasizing that, in order to better enable the piezoelectric material to have a gradient piezoelectric performance difference, the inventors of the present invention found based on experimental facts that when the average particle size of the high piezoelectricity piezoelectric ceramic powder described in step (1) is selected to be 0.5 - 100 μm, a better gradient distribution effect is obtained. If the particle size of the high piezoelectricity piezoelectric ceramic powder is lower than 500 nm, since its dispersibility is good and its fluidity is stronger than that of micron-sized materials, it is not easy to form a gradient, but it is suitable as a piezoelectric product with two piezoelectric performance distribution regions; if the particle size of the high piezoelectricity piezoelectric ceramic powder is higher than 500 μm, the formed material is likely to cause phase separation, which has a greater impact on the continuity of gradient modulation. Through comparative experiments, the inventors of the present invention found that preferably, when the average particle size of the high piezoelectricity piezoelectric ceramic powder described in step (1) is selected to be 0.5 - 50 μm, a better gradient piezoelectric performance difference effect is further obtained.

[0030] It should be noted that in step (4), the thickness of the formed product is limited to not more than 1 cm. This is because the piezoelectric ceramic / low-viscosity polymer composite powder has good compatibility and fluidity in the high-viscosity polymer matrix. If the thickness of the formed product is too large, it will cause the piezoelectric ceramic / low-viscosity polymer composite powder to accumulate in a small area at the bottom of the mold forming, resulting in a piezoelectric product with a poor gradient piezoelectric property or two piezoelectric property distribution regions. However, if the compatibility and fluidity between the two are reduced, it will lead to the inability to form a significant gradient piezoelectric property difference under the inclined condition, thus affecting the positioning accuracy of the subsequent pressure position. Therefore, based on experimental facts, the present invention limits the formed thickness of the prepared piezoelectric product to not more than 1 cm. On this basis, it is usually formed into a plate or a shape material suitable for wearable devices. In addition, due to this thickness limitation and the need to be applicable to the field of wearable devices, those skilled in the art, on the basis of referring to traditional processes, attempt to obtain a mold forming with a gradient change in piezoelectric properties by presenting a trapezoidal change in thickness, such as forming methods of special-shaped molds such as trapezoidal bodies and triangular bodies. If the thickness difference is too small, it is obvious that there will not be a good gradient piezoelectric property difference. If the thickness difference is too large, it will seriously affect its application field and is usually not applicable to the field of wearable devices.

[0031] Among them, the thermosetting forming in step (4) is defined as a thermosetting forming process without shear action, mainly including flat vulcanization pressing plate method, vacuum forming, matched die thermoforming, etc. To better illustrate the present invention and provide a preferred technical solution, the thermosetting forming is the flat vulcanization pressing plate method, and the process parameters of the flat vulcanization pressing plate method are: hot pressing temperature 140 - 200 °C, hot pressing pressure 7 - 20 MPa, hot pressing time 1 - 15 minutes, cold pressing pressure 7 - 20 MPa, cold pressing time 5 - 20 minutes.

[0032] It should be noted that among the above process parameters, the hot pressing time will greatly affect the distribution density of the piezoelectric ceramic / low-viscosity polymer composite powder in the thermosetting polymer matrix in a gradient pattern. Through actual comparative experiments by the inventors of the present invention, it is found that when the inclination angle of the mold is 3° and the inclination length is 10 cm, when the hot pressing time is close to 4 minutes, the distribution gradient difference of the piezoelectric ceramic / low-viscosity polymer composite powder in the prepared piezoelectric product reaches the maximum.

[0033] To better illustrate the present invention and provide a most preferred technical solution:

[0034] In order to prepare a piezoelectric material with a piezoelectric property gradient difference on the overall plane, so as to form a piezoelectric product that can locate the pressure position at multiple points, its preparation method is as follows by weight parts:

[0035] (1) Prepare barium titanate micro-nano powder with an average particle size of 0.5 - 50 μm;

[0036] (2) Mix 100 parts of barium titanate micro-nano powder and 15 - 30 parts of polyethylene wax powder, and conduct kneading treatment to obtain barium titanate / polyethylene wax composite material; among them, the process parameters of the kneading treatment are: kneading time 3 - 7 minutes, rotation speed 15 - 35 revolutions per minute, kneading temperature 110 - 140 °C;

[0037] (3) Crush the barium titanate / polyethylene wax composite material obtained in step (2) to obtain barium titanate / polyethylene wax composite powder; among them, the crushing treatment is carried out by a high-speed crusher, and the process parameters of the high-speed crusher crushing treatment are: temperature 10 - 25 °C, rotation speed 250 - 350 revolutions per minute, cyclic grinding 3 - 7 times;

[0038] (4) Mix the barium titanate / polyethylene wax composite powder obtained in step (3) with LDPE ultra-fine powder in a mass ratio of 1:(1 - 2), mix them evenly, add them to a mold, and use the flat vulcanization press method to form under the condition that the mold is placed at an angle of 3° relative to the horizontal plane, and the inclined length of the formed product is not less than 10 cm and the thickness is not more than 1 cm, then a piezoelectric product with a positionable pressure position is obtained; among them, the process parameters of the flat vulcanization press method are: hot pressing temperature 150 - 180 °C, hot pressing pressure 7 - 15 MPa, hot pressing time 4 minutes, cold pressing pressure 7 - 15 MPa, cold pressing time 5 - 20 minutes.

[0039] To better illustrate the present invention and provide a most preferred technical solution:

[0040] In order to prepare a piezoelectric product with two piezoelectric property distribution regions, and the area ratio of each region is not less than 30%, its preparation method is as follows by weight parts:

[0041] (1) Prepare barium titanate micro-nano powder with an average particle size of 0.1 - 0.5 μm;

[0042] (2) Mix 100 parts of barium titanate micro-nano powder and 15 - 30 parts of polyethylene wax powder, and conduct kneading treatment to obtain barium titanate / polyethylene wax composite material; among them, the process parameters of the kneading treatment are: kneading time 3 - 7 minutes, rotation speed 15 - 35 revolutions per minute, kneading temperature 110 - 140 °C;

[0043] (3) Crush the barium titanate / polyethylene wax composite material obtained in step (2) to obtain barium titanate / polyethylene wax composite powder; among them, the crushing treatment is carried out by a high-speed crusher, and the process parameters of the high-speed crusher crushing treatment are: temperature 10 - 35 °C, rotation speed 250 - 350 revolutions per minute, cyclic grinding 3 - 7 times;

[0044] (4) Mix the barium titanate / polyethylene wax composite powder obtained in step (3) and the LDPE ultrafine powder evenly at a mass ratio of 1:(1-2), add them to a mold, and use the flat vulcanization press plate method to form the mold under the condition that the inclination angle with respect to the horizontal plane is 15°. The inclined length of the formed product is not less than 10 cm and the thickness is not more than 1 cm, thus obtaining a piezoelectric product capable of positioning the pressure position; wherein, the process parameters of the flat vulcanization press plate method are: hot pressing temperature 150-180 °C, hot pressing pressure 7-15 MPa, hot pressing time 5 minutes, cold pressing pressure 7-15 MPa, cold pressing time 5-20 minutes.

[0045] On the other hand, the present invention also provides a piezoelectric product capable of positioning the pressure position prepared by the above preparation method, which can be applied to the fields of wearable devices and pipeline engineering.

[0046] Because the piezoelectric products provided by the present invention have obvious differences in piezoelectric properties at different positions, especially in the one-dimensional direction consistent with the same inclination direction, those skilled in the art can judge the action position of the pressure / external force of the same or similar intensity according to the real-time response of the piezoelectric output signal and the size of the piezoelectric output signal. For example, the piezoelectric properties at different positions of the piezoelectric product provided by the present invention can be measured in advance, and then based on the pressure magnitude and the piezoelectric output intensity, the piezoelectric properties can be calculated through the piezoelectric output calculation formula that is conventional, well-known in the art or can be found in reference books, and the piezoelectric action position can be deduced in reverse according to the piezoelectric properties.

[0047] The main innovation of the present invention is that the inventor accidentally discovered that by compounding piezoelectric ceramic micro-nano powder with a low-viscosity polymer and then adding it to the polymer matrix, the prepared gradient material has good piezoelectric properties and mechanical properties, and at the same time, the piezoelectric signal outputs at different positions on the plate are also different. After research by the inventor, it is considered that this is because the enrichment of the micro-nano piezoelectric ceramic powder in the polymer matrix leads to stress concentration, which can induce large strain, and then a conductive network is constructed by filling the piezoelectric ceramic / low-viscosity polymer composite material in the polymer matrix. At the same time, the aggregation behavior of the piezoelectric ceramic at different positions is different, resulting in different piezoelectric outputs at different positions.

[0048] The present invention has the following beneficial effects:

[0049] 1. The technical solution of the present invention first introduces the inclined press plate method as the main method for forming parts, realizes different piezoelectric properties on piezoelectric parts with the same thickness, and provides a new positioning method for positioning the pressure position by using different piezoelectric properties.

[0050] 2. The process method of the present invention is mature, and at the same time has the characteristics of simple operation and low cost. The gradient composite piezoelectric material prepared can achieve an adjustment of the piezoelectric performance amplitude difference of 22V.

[0051] 3. The present invention provides a skeleton for the piezoelectric ceramic material through a polymer matrix, which can ensure the dimensional stability and erosion resistance stability of the material and extend the service life of the material. At the same time, this preparation method can achieve various part shapes through different molds and has potential beneficial applications in fields such as pipeline engineering and wearable devices.

[0052] Description of the drawings

[0053] Figure 1 It is a photograph of the piezoelectric product prepared in Example 1 of the present invention and a position modulation voltage map. In the figure, the marked points are named ABCD from top to bottom. Among them, the output voltage at point A is 22V, the output voltage at point B is 11V, the output voltage at point C is 2V, and the output voltage at point D is 0.5V. The inclination direction of the mold is from the upper left to the lower right.

[0054] Figure 2 It is a photograph of the environment for testing the piezoelectric properties of the piezoelectric product prepared in the embodiment of the present invention. Detailed implementation manners

[0055] To further understand the present invention, the preferred implementation manners of the present invention will be described below in conjunction with embodiments. However, it should be understood that these descriptions are only for further explaining the features and advantages of the present invention and not for limiting the claims of the invention. Those skilled in the art can draw on the content of this article and appropriately modify the process parameters to achieve. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are all regarded as included in the present invention. The method and application of the present invention have been described through preferred embodiments, and those skilled in the art can obviously make changes or appropriate changes and combinations to the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention. Although it is believed that those of ordinary skill in the art are fully aware of the following terms, the following definitions are still stated to help explain the subject matter disclosed by the present invention.

[0056] In one aspect, the present invention provides a method for preparing a piezoelectric product capable of positioning a pressure position, which comprises the following steps in parts by weight:

[0057] (1) Prepare piezoelectric ceramic powder with a high piezoelectricity and an average particle size of 0.1 - 500 μm;

[0058] (2) Mix and knead 100 parts of piezoelectric ceramic powder with high piezoelectricity and 5 - 50 parts of low-viscosity polymer powder to obtain a piezoelectric ceramic / low-viscosity polymer composite material. Among them, the process parameters of the kneading treatment are: kneading time 3 - 20 minutes, rotation speed 10 - 50 revolutions per minute, and kneading temperature 90 - 150 °C;

[0059] Among them, the low-viscosity polymer is a polymer with a viscosity of 10-500 CPS (140 °C);

[0060] (3) The piezoelectric ceramic / low-viscosity polymer composite obtained in step (2) is pulverized to obtain a piezoelectric ceramic / low-viscosity polymer composite powder with an average particle size not lower than that of the high piezoelectricity piezoelectric ceramic powder and not higher than 600 μm;

[0061] (4) The piezoelectric ceramic / low-viscosity polymer composite powder obtained in step (3) is fully mixed with the ultra-fine powder of the high-viscosity polymer for thermoplastic processing in a mass ratio of 1:(0.5-3), added to a mold, and the mold is thermally cured and formed under the placement condition that the inclination angle with respect to the horizontal plane is 0.5°-20°, and the formed inclined length is not lower than 20 mm and the thickness is not higher than 1 cm, thus obtaining a piezoelectric product capable of positioning the pressure position;

[0062] Among them, the ultra-fine powder of the high-viscosity polymer for thermoplastic processing is a polymer with a viscosity of 500-1000 CPS (140 °C).

[0063] The invention principle of the present invention lies in adopting the polymer processing rheology principle, developing a compression-shear coupling molding experimental equipment, and through the setting of the inclination angle of the mold with respect to the horizontal plane, when the piezoelectric ceramic / low-viscosity polymer composite powder is subjected to a compressive stress, the stress is perpendicular to the contact surface, and the object generates a compressive strain. At this time, the strain rates of each point in the plane are the same; when subjected to a shear action, the stress is parallel to the force-bearing surface, and the maximum shear strain is generated at the near force-bearing point, while the shear strain at the far force-bearing point is zero. The polymer melt deforms along the shear force direction, generating a compression-shear coupling force field, enabling the piezoelectric ceramic particles to flow and concentrate in the direction of the shear force field along with the low-viscosity polymer, forming a gradient concentration in the plane along the shear direction. The prepared piezoelectric product can achieve different piezoelectric outputs at different positions, thereby judging the position of the stress point.

[0064] On this basis, the inventor of the present invention also found that by further limiting the inclination angle of the mold and the thermosetting molding process conditions, the directional flow and concentration of the piezoelectric ceramic particles can be strengthened, thereby preparing a piezoelectric product with a high piezoelectric output in the specified area position and only a low piezoelectric output in the non-specified area position, that is, a piezoelectric product with two piezoelectric property distribution areas on the same overall piezoelectric material, thereby facilitating the functional expansion in subsequent applications.

[0065] In this article, the high piezoelectricity piezoelectric ceramic powder described in step (1) is a well-known highly conductive raw material in the technical field, mainly including barium titanate, lead zirconate titanate, niobate and their composite systems. In one of the embodiments, for cost and environmental protection considerations, barium titanate or barium titanate-based is preferably used.

[0066] In one of the embodiments, the high-voltage piezoelectric ceramic powder described in step (1) can be a commercially available powder with a uniform particle size of 0.1 to 500 μm, or a piezoelectric ceramic micro-nano powder with a uniform particle size of 0.1 to 500 μm obtained by crushing. The uniform particle size can be selected as 0.1 μm, 0.5 μm, 1 μm, 10 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 500 μm, or any range or point value between them. If necessary, during the material preparation process, it also includes pretreatment such as washing and drying in the prior art.

[0067] It should be noted that in step (2), the reason for first preparing the high-voltage piezoelectric ceramic powder and the low-viscosity polymer powder into a piezoelectric ceramic / low-viscosity polymer composite by internal mixing is to allow the high-voltage piezoelectric ceramic powder to be first wrapped by the low-viscosity polymer, thereby having certain mechanical properties, and at the same time improving the interfacial compatibility and fluidity between the high-voltage piezoelectric ceramic and the polymer added subsequently, so that it can flow and concentrate in the direction of the shear force field during thermosetting molding under inclined conditions.

[0068] In one of the embodiments, the low-viscosity polymer described in step (2) is a polymer with a viscosity of 10 to 500 CPS (under the condition of 140 °C). Those skilled in the art can select a suitable conventional low-viscosity polymer according to the above condition limitations, such as a polymer with a viscosity of 10 CPS, 50 CPS, 100 CPS, 150 CPS, 200 CPS, 250 CPS, 300 CPS, 350 CPS, 400 CPS, 450 CPS, 500 CPS, or any range or point value between them (under the condition of 140 °C). To better illustrate the present invention and provide a reference technical solution, the low-viscosity polymer is preferably a polyethylene wax powder, a solid paraffin powder, etc.

[0069] In one of the preferred embodiments, the low-viscosity polymer powder described in step (2) is preferably a polyethylene wax powder. Generally speaking, the polyethylene wax is from a commercial source, and the grade of the polyethylene wax is RLC-657.

[0070] In one of the embodiments, the particle size of the low-viscosity polymer powder described in step (2) can usually be selected to be the same as that of the high-voltage piezoelectric ceramic powder, or a commercially available low-viscosity polymer powder with a particle size of 0.1 to 500 μm or a mesh number of 100 to 2000 meshes is selected, so as to ensure the uniform distribution of the high-voltage piezoelectric ceramic.

[0071] It should be noted that the addition amount of the low-viscosity polymer powder in step (2) is limited to 5-50 parts, because if the addition amount of the low-viscosity polymer is too low, the adhesion between the high-voltage piezoelectric ceramic powder and the low-viscosity polymer itself will be insufficient, and the interfacial interaction with the subsequent added high-polymer substrate will be poor; if the addition amount of the low-viscosity polymer is too high, the concentration of the high-voltage piezoelectric ceramic powder will be reduced, thus affecting the magnitude of the piezoelectric performance gradient difference of the final product. In one implementation, the addition amount of the low-viscosity polymer powder is 5-50 parts, such as 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts or any range or point value between them. During the actual operation process, the specific ratio of the low-viscosity polymer powder to the high-voltage piezoelectric ceramic powder can be reasonably adjusted according to the requirements for the gradient difference of the piezoelectric performance to obtain the required piezoelectric product. In one preferred implementation, the addition amount of the low-viscosity polymer powder is 10-30 parts.

[0072] In one implementation, the piezoelectric ceramic / low-viscosity polymer composite material in step (3) is subjected to a pulverization treatment to obtain a piezoelectric ceramic / low-viscosity polymer composite powder with an average particle size not lower than that of the high-voltage piezoelectric ceramic powder and not higher than 600 μm. The pulverization treatment method of the high-voltage piezoelectric ceramic powder described above can be similarly referred to. To better illustrate the present invention and provide a reference technical solution: the pulverization treatment is carried out by a high-speed pulverizer. Among them, the process parameters of the high-speed pulverizer pulverization treatment are: temperature 5-30 °C, rotation speed 200-400 revolutions per minute, and cyclic grinding 1-9 times.

[0073] In one implementation, the high-viscosity polymer ultrafine powder for thermoplastic processing in step (4) is generally a polymer ultrafine powder that can be thermoplastically processed in the prior art and has a viscosity of 500-1000 CPS (under the condition of 140 °C), such as polymer ultrafine powder with viscosities of 500 CPS, 550 CPS, 600 CPS, 650 CPS, 700 CPS, 750 CPS, 800 CPS, 850 CPS, 900 CPS, 950 CPS, 1000 CPS or any range or point value between them (under the condition of 140 °C). Further preferably, it includes LDPE ultrafine powder, PA11 ultrafine powder, PVDF ultrafine powder, etc.

[0074] In one implementation, the high-viscosity polymer ultrafine powder for thermoplastic processing in step (4) is pulverized to a particle size of 50-500 μm, or a commercially available high-viscosity polymer ultrafine powder with a particle size of 50-500 μm or a mesh number of 30-300 is selected.

[0075] It is worth noting that, in order to better endow the piezoelectric material with a gradient piezoelectric property difference, the inventors of the present invention found based on experimental facts that, in one preferred embodiment, when the average particle size of the high piezoelectricity piezoelectric ceramic powder in step (1) is selected to be 0.5 - 100 μm, a better gradient distribution effect is obtained. If the particle size of the high piezoelectricity piezoelectric ceramic powder is less than 0.5 μm, since its dispersibility is good and its fluidity is stronger than that of micron-sized materials, it is not easy to form a gradient, but it is suitable as a piezoelectric product having two piezoelectric property distribution regions. If the particle size of the high piezoelectricity piezoelectric ceramic powder is higher than 500 μm, the formed material is likely to cause phase separation, which has a great impact on the continuity of gradient modulation. The inventors of the present invention found through comparative experiments that, in a more preferred embodiment, when the average particle size of the high piezoelectricity piezoelectric ceramic powder in step (1) is selected to be 0.5 - 50 μm, a better gradient piezoelectric property difference effect is further obtained.

[0076] In one embodiment, in step (4), the piezoelectric ceramic / low-viscosity polymer composite powder obtained in step (3) and the high-viscosity polymer ultrafine powder for thermoplastic processing are fully mixed evenly at a mass ratio of 1:(0.5 - 3). This mass ratio can be 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3 or any range or point value therebetween; and then added into a mold. The mold is thermally cured and formed under the placement condition that the inclination angle relative to the horizontal plane is 0.5° - 20°, such as 0.5°, 1°, 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, 15°, 16°, 17°, 18°, 19°, 20° or any range or point value therebetween; and the formed inclined length is not less than 20 mm, such as 20 mm, 50 mm, 100 mm, 200 mm, 250 mm, 300 mm or any range or point value therebetween; the thickness is not higher than 1 cm, thus obtaining a piezoelectric product capable of positioning the pressure position.

[0077] It should be noted that in step (4), the thickness of the formed product is limited to no more than 1 cm. This is because the piezoelectric ceramic / low-viscosity polymer composite powder has good compatibility and fluidity in the high-viscosity polymer matrix. If the thickness of the formed product is too large, the piezoelectric ceramic / low-viscosity polymer composite powder will be concentrated in a smaller area at the bottom of the mold, resulting in a piezoelectric product with a poor gradient piezoelectric property or two piezoelectric property distribution regions. However, if the compatibility and fluidity between the two are reduced, it will lead to the inability to form a significant gradient piezoelectric property difference under inclined conditions, thus affecting the positioning accuracy of the subsequent pressure position. Therefore, based on experimental facts, the present invention limits the forming thickness of the prepared piezoelectric product to no more than 1 cm. On this basis, it is usually formed into a plate or a shape material suitable for wearable devices. In one embodiment, the forming thickness is no more than 1 cm, such as 0.1 cm, 0.2 cm, 0.3 cm, 0.4 cm, 0.5 cm, 0.6 cm, 0.7 cm, 0.8 cm, 0.9 cm, 1 cm or any range or point value between them. In addition, due to this thickness limitation and the need to be applicable to the field of wearable devices, those skilled in the art, on the basis of referring to traditional processes, attempt to obtain a mold forming with a gradient change in piezoelectric properties by presenting a trapezoidal change in thickness, such as forming methods of special-shaped molds such as trapezoidal bodies and triangular bodies. If the thickness difference is too small, it is obvious that there will be no good gradient piezoelectric property difference. If the thickness difference is too large, it will seriously affect its application field and is usually not applicable to the field of wearable devices.

[0078] Among them, the thermosetting molding described in step (4) is defined as a thermosetting molding process without shear action, mainly including flat vulcanization press plate method, vacuum molding, matched die thermoforming, etc. In one embodiment, the thermosetting molding is the flat vulcanization press plate method, and the process parameters of the flat vulcanization press plate method are: hot pressing temperature 140-200 °C, such as 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C or any range or point value between them; hot pressing pressure 7-20 MPa, such as 7 MPa, 8 MPa, 9 MPa, 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa, 15 MPa, 16 MPa, 17 MPa, 18 MPa, 19 MPa, 20 MPa or any range or point value between them; hot pressing time 1-15 minutes, such as 1 minute, 2 minutes, 5 minutes, 8 minutes, 10 minutes, 12 minutes, 14 minutes, 15 minutes or any range or point value between them; cold pressing pressure 7-20 MPa, such as 7 MPa, 8 MPa, 9 MPa, 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa, 15 MPa, 16 MPa, 17 MPa, 18 MPa, 19 MPa, 20 MPa or any range or point value between them; cold pressing time 5-20 minutes, such as 1 minute, 2 minutes, 5 minutes, 8 minutes, 10 minutes, 12 minutes, 14 minutes, 15 minutes, 17 minutes, 18 minutes, 20 minutes or any range or point value between them.

[0079] It should be noted that among the above process parameters, the hot pressing time will greatly affect the distribution density of the piezoelectric ceramic / low-viscosity polymer composite powder in the gradient form in the thermosetting polymer matrix. Through actual comparative experiments by the inventors of the present invention, it is found that in one preferred embodiment, when the inclination angle of the mold is 3° and the inclination length is 10 cm, when the hot pressing time is close to 4 minutes, the distribution gradient difference of the piezoelectric ceramic / low-viscosity polymer composite powder in the prepared piezoelectric product reaches the maximum.

[0080] In a more preferred embodiment:

[0081] In order to prepare a piezoelectric material with a piezoelectric performance gradient difference on the overall plane, so as to form a piezoelectric product capable of multi-point positioning of the pressure position, its preparation method is as follows by weight:

[0082] (1) Prepare barium titanate micro-nano powder with an average particle size of 0.5-50 μm;

[0083] (2) Mix 100 parts of barium titanate micro-nano powder and 15 - 30 parts of polyethylene wax powder and conduct kneading treatment to obtain barium titanate / polyethylene wax composite material. Among them, the process parameters of the kneading treatment are: kneading time is 3 - 7 minutes, rotation speed is 15 - 35 revolutions per minute, and kneading temperature is 110 - 140 °C;

[0084] (3) Crush the barium titanate / polyethylene wax composite material obtained in step (2) to obtain barium titanate / polyethylene wax composite powder. Among them, the crushing treatment is carried out by a high-speed crusher, and the process parameters of the high-speed crusher crushing treatment are: temperature is 10 - 25 °C, rotation speed is 250 - 350 revolutions per minute, and cyclic grinding is 3 - 7 times;

[0085] (4) Mix the barium titanate / polyethylene wax composite powder obtained in step (3) with LDPE ultra-fine powder in a mass ratio of 1:(1 - 2), mix them evenly, add them to a mold, and use the flat vulcanization pressing plate method to form under the condition that the mold is placed at an angle of 3° relative to the horizontal plane. Moreover, the inclined length of the formed product is not less than 10 cm and the thickness is not more than 1 cm, then a piezoelectric product with a positionable pressure position is obtained. Among them, the process parameters of the flat vulcanization pressing plate method are: hot pressing temperature is 150 - 180 °C, hot pressing pressure is 7 - 15 MPa, hot pressing time is 4 minutes, cold pressing pressure is 7 - 15 MPa, and cold pressing time is 5 - 20 minutes.

[0086] In one more preferred embodiment:

[0087] In order to prepare a piezoelectric product with two piezoelectric property distribution regions, and the area ratio of each region is not less than 30%, its preparation method is as follows by weight parts:

[0088] (1) Prepare barium titanate micro-nano powder with an average particle size of 0.1 - 0.5 μm;

[0089] (2) Mix 100 parts of barium titanate micro-nano powder and 15 - 30 parts of polyethylene wax powder and conduct kneading treatment to obtain barium titanate / polyethylene wax composite material. Among them, the process parameters of the kneading treatment are: kneading time is 3 - 7 minutes, rotation speed is 15 - 35 revolutions per minute, and kneading temperature is 110 - 140 °C;

[0090] (3) Crush the barium titanate / polyethylene wax composite material obtained in step (2) to obtain barium titanate / polyethylene wax composite powder. Among them, the crushing treatment is carried out by a high-speed crusher, and the process parameters of the high-speed crusher crushing treatment are: temperature is 10 - 35 °C, rotation speed is 250 - 350 revolutions per minute, and cyclic grinding is 3 - 7 times;

[0091] (4) Mix the barium titanate / polyethylene wax composite powder obtained in step (3) with the LDPE ultrafine powder in a mass ratio of 1:(1-2) evenly, add it to a mold, and use the flat vulcanization press plate method to form the mold under the condition that the inclination angle of the mold relative to the horizontal plane is 15°, and the inclined length of the formed product is not less than 10 cm and the thickness is not more than 1 cm, thus obtaining a piezoelectric product capable of positioning the pressure position; wherein, the process parameters of the flat vulcanization press plate method are: hot pressing temperature 150-180 °C, hot pressing pressure 7-15 MPa, hot pressing time 5 minutes, cold pressing pressure 7-15 MPa, cold pressing time 5-20 minutes.

[0092] On the other hand, the present invention also provides a piezoelectric product capable of positioning the pressure position prepared by the above preparation method, which can be applied to the fields of wearable devices and pipeline engineering.

[0093] Because the piezoelectric products provided by the present invention have obvious piezoelectric performance differences at different positions, especially in the one-dimensional direction consistent with the same inclination direction, those skilled in the art can judge the acting position of the pressure / external force of the same or similar intensity according to the real-time response of the piezoelectric output signal and the size of the piezoelectric output signal. For example, the piezoelectric performance at different positions of the piezoelectric product provided by the present invention can be measured in advance, and then based on the pressure magnitude and the piezoelectric output calculation formula that can be obtained by conventional or well-known methods in the art or by querying reference books, the piezoelectric performance can be calculated, and the piezoelectric action position can be deduced in reverse according to the piezoelectric performance.

[0094] The main innovation point of the present invention is that the inventor accidentally discovered that by compounding piezoelectric ceramic micro-nano powder with a low-viscosity polymer and then adding it to the polymer matrix, the prepared gradient material has good piezoelectric performance and mechanical properties, and at the same time, the piezoelectric signal outputs at different positions on the plate are also different. Through research by the inventor, it is considered that this is because the enrichment of the micro-nano piezoelectric ceramic powder in the polymer matrix leads to stress concentration, which can induce large strain, and then a conductive network is constructed by filling the piezoelectric ceramic / low-viscosity polymer composite material in the polymer matrix. At the same time, the aggregation behaviors of the piezoelectric ceramics at different positions are different, resulting in different piezoelectric outputs at different positions.

[0095] The following will further explain the present application with reference to the embodiments. However, those skilled in the art should understand that these embodiments are provided for illustrative purposes only and are not intended to limit the present application.

[0096] Embodiments

[0097] The implementation scheme of the present application will be described in detail below in combination with embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase. The present application should not be construed as being limited by the specific embodiments described.

[0098] 1. Raw materials

[0099] The polyethylene wax is selected as the commercially available brand RLC-657; the LDPE is selected as the commercially available brand LD615. The barium titanate powder is a commercially available conventional product. The copper foil and wire used for testing are both commercially available conventional products.

[0100] 2. Test method

[0101] The instruments used in the test are: a computer (used to control the linear motor at the terminal and convert the source meter information); a linear motor (used to provide the power source required for the test); a source meter (used to monitor the electrical signals released by the materials in the experiment), and a constant temperature and humidity device (used to provide a constant temperature and humidity environment to ensure the stable progress of the experiment). After setting up the piezoelectric test device, the sample is tested in a constant temperature and humidity (temperature is 25 °C, humidity < 7.5%) environment. During the test, the linear motor is controlled through the computer terminal to maintain a constant acceleration (5 m / s 2 ) to continuously impact the sample 125 mm away. The piezoelectric signal is transferred to the source meter through the copper foil on both sides of the sample and a series of conversions to obtain the U-T curve and I-T curve on the computer. By installing a pointed head in front of the linear motor to concentrate the stress position, and at the same time by moving the sample position to ensure that different piezoelectric outputs generated at different positions on the sample plane can be collected.

[0102] Example 1

[0103] The preparation method of a piezoelectric product capable of positioning the pressure position in this example includes the following steps by weight:

[0104] (1) Prepare barium titanate micro-nano powder with an average particle size of 0.5 - 50 μm;

[0105] (2) Mix and knead 100 parts of barium titanate micro-nano powder and 20 parts of polyethylene wax powder to obtain a barium titanate / polyethylene wax composite material; among them, the process parameters of the kneading treatment are: kneading time 5 minutes, rotation speed 30 revolutions per minute, kneading temperature 110 °C;

[0106] (3) The barium titanate / polyethylene wax composite obtained in step (2) is pulverized to obtain a barium titanate / polyethylene wax composite powder; wherein, the pulverization treatment is carried out by a high-speed pulverizer, and the process parameters of the high-speed pulverizer pulverization treatment are: temperature 20°C, rotation speed 300 revolutions per minute, and cyclic milling 5 times;

[0107] (4) The barium titanate / polyethylene wax composite powder obtained in step (3) is fully mixed evenly with LDPE ultrafine powder at a mass ratio of 1:1.5, added to a mold, and the mold is formed by the flat vulcanization press method under the placement condition that the inclination angle with respect to the horizontal plane is 3°, and the inclined length of the formed product is not less than 10 cm and the thickness is not more than 1 cm, thus obtaining a piezoelectric product capable of positioning the pressure position; wherein, the process parameters of the flat vulcanization press method are: hot pressing temperature 170°C, hot pressing pressure 12 MPa, hot pressing time 4 minutes, cold pressing pressure 10 MPa, and cold pressing time 10 minutes.

[0108] The prepared piezoelectric product is as shown in the attached Figure 1 description.

[0109] Example 2

[0110] A preparation method of a piezoelectric product capable of positioning the pressure position in this example includes the following steps by weight:

[0111] (1) Prepare barium titanate micro-nano powder with an average particle size of 0.1 - 0.5 μm;

[0112] (2) Mix 100 parts of barium titanate micro-nano powder and 20 parts of polyethylene wax powder for kneading treatment to obtain a barium titanate / polyethylene wax composite; wherein, the process parameters of the kneading treatment are: kneading time 5 minutes, rotation speed 30 revolutions per minute, and kneading temperature 120°C;

[0113] (3) The barium titanate / polyethylene wax composite obtained in step (2) is pulverized to obtain a barium titanate / polyethylene wax composite powder; wherein, the pulverization treatment is carried out by a high-speed pulverizer, and the process parameters of the high-speed pulverizer pulverization treatment are: temperature 25°C, rotation speed 300 revolutions per minute, and cyclic milling 5 times;

[0114] (4) The barium titanate / polyethylene wax composite powder obtained in step (3) is fully mixed evenly with PVDF ultrafine powder at a mass ratio of 1:1, added to a mold, and the mold is formed by the flat vulcanization press method under the placement condition that the inclination angle with respect to the horizontal plane is 15°, and the inclined length of the formed product is not less than 10 cm and the thickness is not more than 1 cm, thus obtaining a piezoelectric product capable of positioning the pressure position; wherein, the process parameters of the flat vulcanization press method are: hot pressing temperature 170°C, hot pressing pressure 11 MPa, hot pressing time 5 minutes, cold pressing pressure 9 MPa, and cold pressing time 7 minutes.

[0115] The size of the prepared piezoelectric product is 100mm * 100mm * 1mm, and the inclination direction is from top to bottom. After testing, the piezoelectric performance of approximately 40% of the area along its inclination direction is 30V, and the piezoelectric performance of approximately 40% of the area is 5V.

[0116] Application Example 1

[0117] Based on the piezoelectric product prepared in Example 1, according to the points marked in the attached Figure 1 specification, they are named point A, point B, point C, and point D from top to bottom;

[0118] Select point B as the test point among them, and use a linear motor to control through a computer terminal to keep a constant acceleration (5m / s 2 ) to continuously impact point B of the sample 125mm away. Transfer the piezoelectric signal to the source meter through the copper foils on both sides of the sample and obtain the U-T curve and I-T curve on the computer through a series of conversions. After comparison, the obtained piezoelectric output signal is consistent with the signal characterization of point B obtained in the test of Example 1, and it can be judged that the pressure position is point B.

[0119] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A preparation method of a piezoelectric article capable of positioning a pressure position, characterized in that The following steps are included by weight: (1) Prepare high-voltage piezoelectric ceramic powder with an average particle size of 0.1~500μm; The high-voltage piezoelectric ceramic powder is any one or more powders of barium titanate, lead zirconate titanate, and metaniobate; (2) Mixing 100 parts of high-voltage piezoelectric ceramic powder and 5-50 parts of low-viscosity polymer powder and performing banburying treatment to obtain a piezoelectric ceramic / low-viscosity polymer composite material; wherein the process parameters of the banburying treatment are: banburying time 3-20 minutes, rotation speed 10-50 rpm, and banburying temperature 90-150°C; Wherein, the low viscosity polymer is selected from a polymer having a viscosity of 10 to 500 CPS; The low-viscosity polymer is polyethylene wax powder or solid paraffin powder; (3) crushing the piezoelectric ceramic / low-viscosity polymer composite material obtained in step (2) to obtain a piezoelectric ceramic / low-viscosity polymer composite powder having an average particle size not less than the average particle size of the high-voltage piezoelectric ceramic powder and an average particle size not greater than 600 μm; (4) the piezoelectric ceramic / low-viscosity polymer composite powder obtained in step (3) and the high-viscosity polymer ultrafine powder for thermoplastic processing are fully mixed in a mass ratio of 1:(0.5-3), added to a mold, and the mold is thermally cured under the condition that the mold is placed at an inclination angle of 0.5°-20° relative to the horizontal plane, and the inclination length of the mold is not less than 20 mm and the thickness is not more than 1 cm, so as to obtain a piezoelectric product capable of positioning pressure position; Among them, the high-viscosity polymer ultrafine powder for thermoplastic processing is selected from a polymer with a viscosity of 500~1000 CPS; the high-viscosity polymer ultrafine powder for thermoplastic processing is selected from any one or more of LDPE ultrafine powder, PA11 ultrafine powder, and PVDF ultrafine powder.

2. The preparation method according to claim 1, wherein: The amount of the low-viscosity polymer powder added in step (2) is 10 to 30 parts.

3. The preparation method according to claim 1, wherein: The average particle size of the high-voltage piezoelectric ceramic powder in step (1) is selected to be 0.5-50 μm.

4. The preparation method according to claim 1, wherein The preparation method is as follows by weight: (1) Prepare barium titanate micro-nano powder with an average particle size of 0.5~50μm; (2) 100 parts of barium titanate micro-nano powder and 15-30 parts of polyethylene wax powder are mixed and kneaded to obtain a barium titanate / polyethylene wax composite material; wherein the process parameters of the kneading treatment are: kneading time 3-7 minutes, rotation speed 15-35 rpm, and kneading temperature 110-140°C; (3) subjecting the barium titanate / polyethylene wax composite material obtained in step (2) to pulverization to obtain a barium titanate / polyethylene wax composite powder; wherein the pulverization is performed by a high-speed pulverizer, and the process parameters of the high-speed pulverizer pulverization are: temperature 10-25° C., rotation speed 250-350 rpm, and cyclic grinding 3-7 times; (4) The barium titanate / polyethylene wax composite powder obtained in step (3) and the LDPE ultrafine powder are thoroughly mixed evenly at a mass ratio of 1:(1 - 2), and then added into a mold. The mold is formed by the flat vulcanization press method under the condition that the inclination angle relative to the horizontal plane is 3°. The inclined length of the formed product is not less than 10 cm and the thickness is not more than 1 cm, thus obtaining a piezoelectric product capable of positioning the pressure position. Among them, the process parameters of the flat vulcanization press method are: hot pressing temperature 150 - 180 °C, hot pressing pressure 7 - 15 MPa, hot pressing time 4 minutes, cold pressing pressure 7 - 15 MPa, and cold pressing time 5 - 20 minutes.

5. The preparation method according to claim 1, wherein The preparation method thereof by weight parts is as follows: (1) Prepare barium titanate micro-nano powder with an average particle size of 0.1 - 0.5 μm. (2) Mix and knead 100 parts of barium titanate micro-nano powder and 15 - 30 parts of polyethylene wax powder to obtain a barium titanate / polyethylene wax composite material. Among them, the process parameters of the kneading treatment are: kneading time 3 - 7 minutes, rotation speed 15 - 35 revolutions per minute, and kneading temperature 110 - 140 °C. (3) Crush the barium titanate / polyethylene wax composite material obtained in step (2) to obtain barium titanate / polyethylene wax composite powder. Among them, the crushing treatment is carried out by a high-speed crusher. The process parameters of the high-speed crusher crushing treatment are: temperature 10 - 35 °C, rotation speed 250 - 350 revolutions per minute, and cyclic grinding 3 - 7 times. (4) The barium titanate / polyethylene wax composite powder obtained in step (3) and the LDPE ultrafine powder are thoroughly mixed evenly at a mass ratio of 1:(1 - 2), and then added into a mold. The mold is formed by the flat vulcanization press method under the condition that the inclination angle relative to the horizontal plane is 15°. The inclined length of the formed product is not less than 10 cm and the thickness is not more than 1 cm, thus obtaining a piezoelectric product capable of positioning the pressure position. Among them, the process parameters of the flat vulcanization press method are: hot pressing temperature 150 - 180 °C, hot pressing pressure 7 - 15 MPa, hot pressing time 5 minutes, cold pressing pressure 7 - 15 MPa, and cold pressing time 5 - 20 minutes.

6. A piezoelectric product capable of positioning the pressure position prepared by the preparation method of the piezoelectric product capable of positioning the pressure position as described in claim 1.

7. The piezoelectric article capable of positioning the pressure position according to claim 6 is applied to the field of wearable devices and the field of pipeline engineering, and is characterized in that: In the one-dimensional direction consistent with the inclined direction, through the real-time response of the piezoelectric output signal, judge the acting position of the pressure or external force of the same or similar intensity according to the magnitude of the piezoelectric output signal.

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