Resin molded body, piezoelectric element, wearable device, and method of manufacturing resin molded body

Abstract

To provide a resin molded body capable of increasing a displacement quantity in consideration of the fact that a piezoelectric element is required to transmit a larger stimulus.SOLUTION: A resin molded body has a base material 10 being a cured object of a curable resin, and one or more dielectric particle groups 20 located in the base material 10 and extended in an arbitrary direction. The dielectric particle group 20 is composed of two or more dielectric particles oriented in the arbitrary direction. The dielectric particle group 20 has a region formed by the dielectric particles being spaced apart from each other in the arbitrary direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a resin molded body, a piezoelectric element, a wearable device, and a method for manufacturing a resin molded body. [Background technology]

[0002] There is a so-called haptics technology (touch sensation technology) that provides a user with skin sensation feedback by applying force, vibration, movement, etc. In the haptics technology, the tactile sensation is fed back via a wearable device having an actuator.

[0003] As a piezoelectric element such as an actuator, for example, a piezoelectric element has been proposed that has a piezoelectric layer containing piezoelectric particles in a matrix containing a polymer material, electrode layers provided on both sides of the piezoelectric layer, and a protective layer provided on the side of the electrode layer opposite the piezoelectric layer, the protective layer having a resin base material and at least one inorganic layer provided on the resin base material, and the water vapor transmission rate is within a specific range (Patent Document 1). According to the invention of Patent Document 1, changes in mechanical characteristics and electrical properties due to humidity in the external environment are suppressed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2023 / 054019 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the piezoelectric element is required to transmit a larger stimulus, and therefore a piezoelectric body with a larger amount of displacement is required. Therefore, an object of the present invention is to provide a resin molded body that can increase the amount of displacement. [Means for solving the problem]

[0006] The present invention has the following aspects. <1> The dielectric film has a base material which is a cured product of a curable resin, and one or more dielectric particle groups which are located in the base material and extend in any direction; The dielectric particle group is composed of two or more dielectric particles oriented in the arbitrary direction, The group of dielectric particles has a region a where the dielectric particles are spaced apart from each other in the arbitrary direction. <2> Two or more of the dielectric particle groups are included, The dielectric particle groups are spaced apart from each other in a direction perpendicular to the arbitrary direction. <1> The resin molded article according to claim 1. <3> When the arbitrary direction is defined as the Y direction, a direction perpendicular to the Y direction is defined as the X direction, and a direction perpendicular to the Y direction and the X direction is defined as the Z direction, a ratio (β / α ratio) of an area β occupied by the dielectric particles in a ZY plane to an area α occupied by the dielectric particles in a XZ plane is greater than 1.2 and less than 500; a ratio (γ / α ratio) of an area γ occupied by the dielectric particles when viewed in the XY plane to an area β occupied by the dielectric particles when viewed in the XZ plane is greater than 1.2 and not greater than 500; The proportion of the dielectric particles in the XZ plane is 3 to 100% by area. <1> or <2> The resin molded article according to claim 1. <4> A part or all of the dielectric particle group has a tDa / L ratio of 0.05 to 0.9, which is determined by the following measurement method. <1> ~ <4> 2. The resin molded article according to claim 1 . <Measurement method> A straight line is drawn in the orientation direction of the dielectric particles for the dielectric particle group, and the length Da of region a on this straight line in the orientation direction and the length L of the dielectric particle group in the orientation direction are measured. The total tDa of the lengths Da on the straight line is divided by the length L to obtain the tDa / L ratio. <5> The aspect ratio of the dielectric particles is 1.0 to 200. <1> ~ <4> 2. The resin molded article according to claim 1 .

[0007] <6> A pair of electrodes and a magnetic field sensor disposed between the pair of electrodes <1> ~ <5> and a resin molded body according to any one of the preceding claims, The pair of electrodes faces each other in an orientation direction of the dielectric particles in the dielectric particle group.

[0008] <7> <6> A wearable device having the actuator described in claim 1.

[0009] <8> A dispersion liquid including an uncured resin and the dielectric particles having two or more magnetic properties dispersed in the uncured resin is subjected to a magnetic field in an arbitrary direction, while the uncured resin is cured. <1> ~ <5> 13. The method for producing the resin molded article according to claim 12, Effect of the Invention

[0010] According to the resin molded article of the present invention, the amount of displacement can be further increased. [Brief description of the drawings]

[0011] [Figure 1] 1 is a perspective view of a resin molded body according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a side view of a dielectric particle group according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a cross-sectional view showing an example of an apparatus for producing a resin molded body. [Figure 4] 1 is a cross-sectional view of an actuator according to an embodiment of the present invention. [Diagram 5] 1A is a plan view X-ray CT image of the resin molded body of Example 1. FIG. 1B is a perspective view X-ray CT image of the resin molded body of Example 1. [Figure 6] 1A is a plan view X-ray CT image of the resin molded body of Comparative Example 1. FIG. 1B is a perspective view X-ray CT image of the resin molded body of Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] In this specification and claims, the use of "to" indicating a range of numerical values ​​means that the numerical values ​​before and after it are included as the lower limit and upper limit.

[0013] (Resin molding) The resin molded body of the present invention has a base material of a cured resin and a group of dielectric particles located in the base material. The resin molded body is a composition having a base material and a group of dielectric particles. The resin molded body functions as a piezoelectric layer of a piezoelectric element such as an actuator, for example. Hereinafter, one embodiment of the resin molded article of the present invention will be described. The resin molded body 1 in FIG. 1 has a base material 10 and one or more dielectric particle groups 20 positioned within the base material 10. In this embodiment, the resin molded body 1 is a rectangular flat plate in a plan view. The dielectric particle group 20 extends in the thickness direction of the resin molded body 1 (Y direction).

[0014] The base material 10 is a cured resin. The term "cured resin" is a concept that excludes fluids (liquids, slurries, and sols) and is in the form of a solid or gel.

[0015] The base material 10 is a cured product of a curable resin. The type of the curable resin can be appropriately determined in consideration of the application of the resin molded body 1 and other factors. Examples of the curable resin include energy ray curable resins such as thermosetting resins and photocurable resins. Examples of the thermosetting resin include silicone resins, polyurethanes, thermosetting polyimides, phenolic resins, unsaturated polyesters, etc. Examples of the photocurable resin include acrylic resins, epoxy resins, etc. Among these, from the viewpoint of reducing the viscosity of the dispersion liquid used in the manufacturing method described below and making it easier to orient the dielectric particles, the resin constituting the base material 10 is preferably a thermosetting resin, and more preferably a silicone resin.

[0016] The flexural modulus of the base material 10 is preferably 0.1 to 100,000 MPa, more preferably 1.0 to 10,000 MPa, and even more preferably 10 to 2,000 MPa. When the flexural modulus is equal to or greater than the lower limit, the mechanical strength can be further increased. When the flexural modulus is equal to or less than the upper limit, the displacement of the resin molded body 1 can be further increased.

[0017] The size of the base material 10 (that is, the size of the resin molded body 1) is not particularly limited, and is appropriately determined taking into consideration the application and the like. For example, when the resin molded body 1 is used as a piezoelectric layer of an actuator, the size of the base material 10 is, for example, 10 to 100 mm in the X direction, 0.1 to 2.0 mm in the Y direction, and 10 to 100 mm in the Z direction. The size of the base material 10 is determined by measuring 10 arbitrary points by X-ray CT and averaging the measurements.

[0018] The dielectric particle group 20 includes two or more dielectric particles oriented in the Y direction. The dielectric particle group 20 has, for example, a cylindrical or polygonal columnar shape extending in the Y direction. Any one of the dielectric particle groups 20 and another adjacent one of the dielectric particle groups 20 are spaced apart from each other in the X direction and the Z direction (i.e., the planar direction). That is, the dielectric particle groups 20 are spaced apart from each other in the directions (X direction, Z direction) perpendicular to the orientation direction (Y direction) of the dielectric particles. In the dielectric particle group 20 of FIG. 2, the dielectric particles 22 are oriented in the Y direction and form a group of columns extending in the Y direction. The term "orientation" refers to a state in which the distribution of the dipole moment directions is biased in a certain direction from a random state. In this embodiment, the dipole moment directions of the dielectric particles 22 are biased in the Y direction.

[0019] The dielectric particles 22 have insulating properties. From the viewpoint of more easily orienting the dielectric particles 22 in the manufacturing method described below, it is preferable that the dielectric particles 22 have magnetic properties. Examples of the dielectric particles 22 include particles of an insulating magnetic material, particles of an insulating material such as ceramics, particles of an insulating material coated with an insulating magnetic material, etc. Examples of the insulating magnetic material include insulating ferrite (Ni-Zn-Cu ferrite), etc.

[0020] The average particle diameter of the dielectric particles 22 is, for example, preferably 10 to 100 μm, more preferably 10 to 80 μm, and further preferably 10 to 50 μm. When the average particle diameter of the dielectric particles 22 is equal to or greater than the above lower limit, the orientation can be further improved. When the average particle diameter of the dielectric particles 22 is equal to or less than the above upper limit, the packing density of the dielectric particles 22 in the dielectric particle group 20 can be further increased. The packing density of the dielectric particles 22 in the dielectric particle group 20 is the content of the dielectric particles 22 in the dielectric particle group 20 on a volume basis. The average particle size of the dielectric particles 22 is a weight average particle size determined by a particle size distribution meter (laser diffraction / scattering method).

[0021] The aspect ratio of the dielectric particles 22 is preferably 1.0 to 200, more preferably 1.0 to 100, and further preferably 1.0 to 10. When the aspect ratio of the dielectric particles 22 is equal to or greater than the above lower limit, the orientation can be further improved. When the aspect ratio of the dielectric particles 22 is equal to or less than the above upper limit, the packing density of the dielectric particles 22 in the dielectric particle group 20 can be further increased. The aspect ratio is a value determined by a microscope (static image analysis method).

[0022] 2, the dielectric particle group 20 has one or more regions a in which the dielectric particles 22 are spaced apart from each other in the Y direction (i.e., the orientation direction). In this embodiment, the dielectric particle group 20 has two regions a on a virtual line P extending in the Y direction. The number of regions a of the dielectric particle group 20 may be one or more, preferably two or more, and more preferably three or more. The upper limit of the number of regions a is, for example, five.

[0023] The length L of the dielectric particle group 20 in the Y direction is appropriately determined taking into consideration the length (thickness) of the base material 10 in the Y direction, the intended use, etc. The length L is, for example, preferably 1 to 100% of the length of the base material 10 in the Y direction, more preferably 10 to 75%, and even more preferably 20 to 50%. The length L is the maximum length in the Y direction. The length L is a value measured by X-ray CT. Both ends of the dielectric particle group 20 in the Y direction may or may not be exposed on the surface of the base material 10. For example, when the resin molded body 1 is used as a piezoelectric layer, from the viewpoint of preventing electrical conduction with the electrodes, it is preferable that both ends of the dielectric particle group 20 in the Y direction are not exposed from the base material 10 (both ends are covered by the base material 10). That is, it is preferable that the length L is less than 100% of the length of the base material 10 in the Y direction. The length L can be adjusted by combining the distance between the magnetic pins of the magnetic field generating device used in the curing step described below, the content of the dielectric particles in the dispersion, the viscosity of the dispersion, and the like.

[0024] When a straight imaginary line P is drawn in the orientation direction of the dielectric particles in the dielectric particle group 20, the length Da of the region a on the imaginary line P (i.e., the distance between the dielectric particles 22) is preferably 1 to 250 μm, more preferably 1 to 100 μm, and even more preferably 1 to 20 μm. When the length Da is equal to or greater than the above lower limit, the amount of displacement can be increased. When the length Da is equal to or less than the above upper limit, the packing density of the dielectric particles 22 in the dielectric particle group 20 can be increased. The length Da is a value measured by X-ray CT. The length Da can be adjusted by combining the distance between the magnetic pins of the magnetic field generating device used in the curing step described below, the content of the dielectric particles in the dispersion, the viscosity of the dispersion, and the like.

[0025] The ratio (tDa / L ratio) of the total tDa of the lengths Da on the straight virtual line P to the length L of the dielectric particle group 20 is preferably 0.05 to 0.9, more preferably 0.05 to 0.6, and even more preferably 0.1 to 0.3. When the tDa / L ratio is equal to or greater than the lower limit, the amount of displacement can be increased. When the tDa / L ratio is equal to or less than the upper limit, the packing density of the dielectric particles 22 in the dielectric particle group 20 can be increased. The tDa / L ratio is obtained by dividing the tDa on the virtual line P by the length L. In the tDa / L ratio, virtual lines P are drawn at different positions in the X direction or Z direction for one dielectric particle group 20, the tDa on each virtual line P is obtained, and the average value is used as the tDa. The number of virtual lines P is, for example, four. For example, when measuring Da, two virtual lines P are drawn at different positions when viewed from the X direction, and two virtual lines P are drawn at different positions when viewed from the Z direction.

[0026] The ratio (by number) of the dielectric particles 20 having a tDa / L ratio in the above range (specific dielectric particles) is preferably 50% or more, more preferably 75% or more, and even more preferably 100%. That is, the specific dielectric particles 20 may be a part or the whole.

[0027] The ratio (β / α ratio) of the area β occupied by the dielectric particles 22 in the ZY plane view (i.e., viewed from the X direction) to the area α occupied by the dielectric particles 22 in the XZ plane view (i.e., viewed from the Y direction) is preferably more than 1.2 and not more than 500, more preferably more than 1.2 and not more than 250, and even more preferably more than 1.2 and not more than 100. When the β / α ratio is equal to or more than the above lower limit, the degree of orientation of the dielectric particles 22 in the Y direction is higher. The ratio (γ / α ratio) of the area γ occupied by the dielectric particles 22 in the XY plane view (i.e., viewed from the Z direction) to the area α is preferably more than 1.2 and not more than 500, more preferably more than 1.2 and not more than 250, and even more preferably more than 1.2 and not more than 100. When the γ / α ratio is equal to or more than the lower limit, the degree of orientation of the dielectric particles 22 in the Y direction is higher. The areas α, β, and γ are values ​​measured by X-ray CT observation. The measurement range is, for example, 1.2 to 17.7 mm 2 Let the areas α, β, and γ be 1 mm2 Calculate as the area per unit.

[0028] The volume ratio of the dielectric particle group 20 to the resin molding 1 is, for example, preferably 0.01 to 50 volume %, more preferably 0.05 to 20 volume %, and even more preferably 0.1 to 10 volume %. When the volume ratio of the dielectric particle group 20 to the dielectric resin molding 1 is equal to or greater than the above lower limit, the piezoelectric performance can be further improved. When the volume ratio of the dielectric particle group 20 to the dielectric resin molding 1 is equal to or less than the above upper limit, short circuits between the dielectric particle groups 20 can be more reliably prevented. The volume of the dielectric particle group 20 is obtained by using a volume rendering method for the X-ray CT image.

[0029] The content (filling density) of the dielectric particles 22 in the dielectric particle group 20 on a volume basis is, for example, preferably 1 to 75 volume %, more preferably 1 to 50 volume %, and further preferably 1 to 25 volume %. When the content of the dielectric particles 22 in the dielectric particle group 20 is equal to or more than the above lower limit, the piezoelectric performance can be further improved. When the content of the dielectric particles 22 in the dielectric particle group 20 is equal to or less than the above upper limit, the length Da is increased, the tDa / L ratio is increased, and the amount of displacement is further increased. The volumes of the dielectric particle group 20 and the dielectric particles 22 are obtained by using a volume rendering method on the X-ray CT image.

[0030] The number of the dielectric particles 20 is 1 to 100 pieces / mm when viewed from the XZ plane. 2 is preferable, and 1 to 50 pieces / mm 2 More preferably, 1 to 25 pieces / mm 2 is more preferable. When the number of the dielectric particle groups 20 is equal to or greater than the above lower limit, the piezoelectric performance can be further improved. The more the dielectric particles 22 are, the more likely it is that the dielectric particles 22 are filled up to the ends in the XZ plane view, and the dielectric particles are exposed to the outside of the piezoelectric layer, resulting in electrical conduction. Therefore, when the number of the dielectric particle groups 20 is equal to or less than the above upper limit, electrical conduction can be more reliably prevented.

[0031] It is preferable that no dielectric particles 22 are present in the region b between any of the dielectric particle groups 20 and other dielectric particle groups 20 adjacent to the arbitrary dielectric particle group 20. When the dielectric particles 22 are present in the region b, the content of the dielectric particles 22 in the region b is preferably less than 1 volume %, more preferably less than 0.5 volume %, and even more preferably less than 0.1 volume %. That is, the content of the dielectric particles 22 in the region b is preferably 0 volume % or more and less than 1 volume %, more preferably 0 volume % or more and less than 0.5 volume %, more preferably 0 volume % or more and less than 0.1 volume %, and particularly preferably 0 mass %. When the content of the dielectric particles 22 in the region b is equal to or less than the above upper limit, the leakage current suppression effect can be further enhanced. The "leak current suppression effect" is an effect of suppressing a drop in applied voltage.

[0032] In the region b, the separation distance Db between any one of the dielectric particle groups 20 and another one of the dielectric particle groups 20 adjacent thereto can be appropriately determined taking into consideration the use of the resin molded body 1 and the like. The separation distance Db is, for example, preferably 10 to 500 μm, more preferably 10 to 250 μm, and even more preferably 10 to 100 μm. When the separation distance Db is equal to or greater than the above lower limit, electrical conduction between the dielectric particle groups 20 can be more reliably prevented. When the separation distance Db is equal to or less than the above upper limit, the packing density of the dielectric particles 22 in the dielectric particle groups 20 can be more increased. The separation distance Db is the distance between the closest outer edges of the dielectric particle groups 20. The separation distance Db can be adjusted by a combination of the separation distance of the magnetic pins of the magnetic field generating device used in the curing step described later, the content of the dielectric particles in the dispersion, the viscosity of the dispersion, and the like. The distance Db is a value measured by X-ray CT.

[0033] In the above-described embodiment, the dielectric particle group extends in the thickness direction of the resin molding (Y direction in FIG. 1). However, the present invention is not limited thereto, and the dielectric particle group may extend in any of the planar directions (for example, X direction or Z direction).

[0034] In the above-described embodiment, the dielectric particles are oriented in the thickness direction of the resin molding (Y direction in FIG. 1). However, the present invention is not limited thereto, and the dielectric particles may be oriented in any of the planar directions (for example, X direction or Z direction).

[0035] In the above embodiment, the resin molded body is a flat plate having a rectangular shape in a plan view, but the shape of the resin molded body can be appropriately determined in consideration of the application. The shape of the resin molded body may be, for example, a flat plate having a polygonal shape other than a rectangular shape in a plan view, a flat plate having a circular shape in a plan view, a cylinder, a polygonal prism, or a polyhedron.

[0036] (Method of manufacturing resin molded body) The method for producing a resin molded product of the present invention includes a step of curing an uncured resin while orienting the dielectric particles in a dispersion liquid in which two or more dielectric particles are dispersed, in a given direction (curing step).

[0037] Hereinafter, one embodiment of the method for producing a resin molded body will be described. The method for producing a resin molded body according to this embodiment includes a filling step, a curing step, and a demolding step. An example of a manufacturing apparatus used in the manufacturing method of this embodiment will be described. The manufacturing apparatus 200 in FIG. 3 includes a pair of magnetic field generating units 210 facing each other in the Y direction, a pair of molds 220 facing each other in the Y direction, and a spacer 230. The pair of molds 220 are positioned between the pair of magnetic field generating units 210. The spacer 230 is positioned between the pair of molds 220, circumferentially arranged in a plan view, and forms a rectangular space 202 therein. The space 202 is a space surrounded by the pair of molds 220 and the spacer 230. In this embodiment, an insulating sheet 240 is positioned on the inner surface of the mold 220 (the surface facing the space 202). The magnetic field generating unit 210 has a magnetic pin 212 .

[0038] For example, a resin frame can be used as the spacer 230. The thickness of the spacer 230 is appropriately determined depending on the desired thickness of the resin molded body.

[0039] An example of the insulating sheet 240 is a polyimide sheet. The thickness of the insulating sheet 240 is not particularly limited.

[0040] In the filling step, the dispersion liquid 250 is poured into the space 202. At this time, it is preferable that the space 202 is filled with the dispersion liquid 250 to be liquid-tight.

[0041] The dispersion 250 has two or more dielectric particles dispersed in an uncured resin. The content of the dielectric particles in the dispersion liquid 250 is preferably 1 to 30 mass %, more preferably 1 to 20 mass %, and even more preferably 1 to 10 mass %, relative to the total mass of the dispersion liquid 250. When the content of the dielectric particles in the dispersion liquid 250 is equal to or more than the above lower limit, the number of regions a in the dielectric particle group and the length Da of the region a can be made more appropriate. When the content of the dielectric particles in the dispersion liquid 250 is equal to or more than the above lower limit, the dielectric particle groups 20 in the regions b can be spaced apart at a more appropriate distance (separation distance Db) in the curing step.

[0042] The content of the uncured resin in the dispersion 250 is preferably 10 to 100 mass %, more preferably 20 to 100 mass %, and even more preferably 50 to 100 mass %, relative to the total mass of the dispersion 250. When the content of the uncured resin in the dispersion 250 is equal to or more than the above lower limit, the viscosity of the dispersion 250 can be increased.

[0043] The dispersion liquid 250 may contain components (optional components) other than the uncured resin and the dielectric particles. Examples of the optional components include pigments, polymerization initiators, polymerization accelerators, etc. The type and content of the optional components in the dispersion liquid 250 can be appropriately determined depending on the type of uncured resin, the type of the optional components, etc.

[0044] The viscosity of the dispersion liquid 250 is, for example, preferably 1000 to 20000 mP·s, and more preferably 1000 to 10000 mP·s. When the viscosity is equal to or greater than the lower limit, the dispersion liquid 250 can be handled more easily. When the viscosity is equal to or less than the upper limit, the dispersion liquid 250 quickly spreads throughout the space 202 when filled therein, and the dielectric particle group 20 can be more easily formed in the orientation operation described below. The viscosity of the dispersion 250 is a value measured at 25° C. using a Brookfield viscometer. The viscosity of the dispersion 250 can be adjusted by combining the type of uncured resin, the temperature of the dispersion 250, and the like.

[0045] The dispersion liquid may be prepared in advance, or may be prepared (prepared) before the filling step.

[0046] After the filling step, a curing step is performed in which the dielectric particles in the dispersion are oriented (orientation operation) while the uncured resin is cured to form a base material (curing operation). After the filling step, a magnetic field is generated between the magnetic pins 212 of the opposing magnetic field generating units 210 (orientation operation). When the magnetic field is generated, the dielectric particles in the dispersion liquid in the space 202 are oriented in the Y direction, forming the dielectric particle group 20. The magnetic flux density in the orientation operation can be determined taking into consideration the type of dielectric particles, the desired thickness of the resin molded article, and the like. For example, it is preferably 0.01 to 10T, and more preferably 0.05 to 5T. The orientation time in the orientation operation (the time during which magnetic force is applied) can be determined taking into consideration the magnetic flux density, the type of dielectric particles, the desired thickness of the resin molded body, etc., and is, for example, preferably 1 to 30 minutes, more preferably 3 to 15 minutes.

[0047] While the orientation operation is being carried out, the uncured resin in the dispersion is cured to form a resin molded body (curing operation). The method for curing the uncured resin is determined according to the type of the uncured resin. For example, if the uncured resin is a thermosetting resin, the dispersion in the space 202 is heated to cure the uncured resin. The heating temperature can be appropriately determined according to the type of the uncured resin. If the uncured resin is a thermoplastic resin, the dispersion is cooled to cure the uncured resin (the above is the curing process).

[0048] In the demolding step, the resin molded body in which the uncured resin has been cured is removed from the manufacturing apparatus 200. In this manner, a resin molded body is obtained.

[0049] In the above embodiment, the orientation is performed by applying a magnetic field, but the present invention is not limited to this, and the dielectric particles may be oriented by other methods.

[0050] (Piezoelectric element) The piezoelectric element of the present invention has the resin molded article of the present invention located between a pair of opposing electrodes. Examples of the piezoelectric element include an actuator, a vibrator, a speaker, and a sensor. An example of the piezoelectric element of the present invention will be described below by taking an actuator as an example.

[0051] 4 has a pair of opposing electrodes 120, a resin molded body 1 located between the pair of electrodes 120 in contact with the electrodes 120, and an insulating film 110 located on the surface of the electrode 120 (the surface opposite to the surface on which the resin molded body 1 is located). A wiring 130 is connected to the electrode 120.

[0052] The electrode 120 is not particularly limited, and an electrode can be selected according to the purpose.

[0053] An example of the insulating film 110 is a resin film. There are no particular limitations on the resin film as long as it has insulating properties, and an example of the resin film is polyvinyl chloride. Furthermore, the thickness of the insulating film 110 is not particularly limited.

[0054] A method for using the actuator 100 will now be described. Electricity is supplied to the electrodes 120 via the wiring 130, and a voltage is applied between the electrodes 120. When a voltage is applied between the electrodes 120, the dielectric particle group 20 expands and contracts in the Y direction in response to the applied voltage. At this time, since the dielectric particles of the dielectric particle group 20 are oriented in the Y direction and have the region a, the degree of expansion and contraction can be increased. Therefore, by using the actuator 100, a greater stimulus can be transmitted to the user.

[0055] As described above, the resin molded body of the present invention generates a larger amount of displacement. Even if the resin molded body of the present invention is thin, it generates a large amount of displacement in the thickness direction. For this reason, a piezoelectric element having the resin molded body of the present invention is suitable for application to wearable devices such as smart wear, immersive game machines (controllers, etc.), and VR devices (tactile sensation reproducing gloves, etc.). EXAMPLES

[0056] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples.

[0057] (Raw materials used) <Resin> Thermosetting resin: Silicone resin, Silpot 184, liquid (25°C), manufactured by Dow Corning Toray. <Dielectric particles> Insulating ferrite: Ni-Zn-Cu ferrite particles, average particle size = 40 μm, NZ40, manufactured by Powder Tech Co., Ltd.

[0058] <Measurement method> <Dielectric particles in resin molded body> A 3D image was created on the analysis software using the cross-sectional images obtained by X-ray CT. Next, an arbitrary region inside the sample was extracted from the 3D image, and the volume occupancy (= content) of the dielectric particles identified by binarization processing within the region was calculated.

[0059] <Dielectric particles in dielectric particle group (packing density)> A 3D image was created on the analysis software using the cross-sectional images obtained by the X-ray CT. Next, an arbitrary area inside the sample was extracted from the 3D image, and the dielectric particles were identified by binarization processing within the area. The volume of the identified dielectric particle group and the volume of the dielectric particles were calculated, and the packing density was calculated.

[0060] <Piezoelectric constant d33> A pressing force was applied to each resin molded body using a vibrator under the conditions of load F = 1N, dynamic load = 1.5N, and frequency = 1Hz. The electric charge Q (coulomb) generated when the pressing force was applied was measured as the piezoelectric constant d33 (amount of electric charge) using Piezo Leader (manufactured by Lead Techno Co., Ltd.). Note that the piezoelectric constant dij means the load in the j direction and the charge in the i direction, and d33 is the load in the thickness direction of the resin molded body and the charge in the thickness direction. Immediately after production, the piezoelectric constant d33 of the resin molded article was measured at five random locations, and the arithmetic mean value of these measurements was taken as the piezoelectric constant d33. It can be said that the larger the piezoelectric constant d33, the larger the amount of displacement.

[0061] <Examples 1 to 3> According to Table 1, the dielectric particles were added to 20 g of a thermosetting resin and stirred to prepare a dispersion liquid. This dispersion liquid was degassed at 9.3 Pa (preparation operation). Using a manufacturing apparatus similar to the manufacturing apparatus 200 in Fig. 3, the space surrounded by the mold and spacer was filled with the dispersion (filling step), and the dispersion was heated (140°C, 5 minutes) while applying a magnetic force, and cured (orientation operation and curing operation) to manufacture the resin molded bodies of each example. The manufacturing conditions are shown below. For the resulting resin molded body, the volume occupancy of the dielectric particles, the packing density, and the piezoelectric constant d33 were determined, and the results are shown in the table. An X-ray CT image of the resin molded article of Example 1 is shown in FIG.

[0062] ≪Manufacturing conditions≫ · Dimensions of space 202: Y direction (thickness) 0.25 mm × X direction 55 mm × Z direction 75 mm. Insulation sheet: Polyimide sort, Kapton film (product name). · Orientation operation: magnetic flux density 0.1T x 7 minutes.

[0063] Comparative Example 1 A resin molded product was obtained in the same manner as in Example 3, except that the orientation operation was omitted. For the resulting resin molded body, the volume occupancy of the dielectric particles, the packing density, and the piezoelectric constant d33 were determined, and the results are shown in the table. The X-ray CT image of the resin molded body of Comparative Example 1 is shown in FIG.

[0064] [Table 1]

[0065] As shown in Table 1, the piezoelectric constant d33 was 5.92 to 9.45 pC / N in Examples 1 to 3. When Examples 1 to 3 to which the present invention was applied were observed by X-ray CT, the presence of Region a was confirmed. The piezoelectric constant d33 of Comparative Example 1 in which the dielectric particles were not oriented was 3.33 pC / N. From the above results, it was confirmed that the amount of displacement can be increased by applying the present invention. [Explanation of symbols]

[0066] 1 Resin molding 10 Base material 20 Dielectric Particles 22 Dielectric particles 100 Actuator 110 Insulating film 120 electrodes 200 Manufacturing equipment 210 Magnetic field generating unit 212 Magnetic pin 220 Mold 230 Spacer 250 Dispersion a area

Claims

1. A base material that is a cured product of a curable resin, and one or more dielectric particle groups that are located in the base material and extend in any direction, The dielectric particle group is composed of two or more dielectric particles oriented in the arbitrary direction, the group of dielectric particles has a region a where the dielectric particles are spaced apart from each other in the arbitrary direction.

2. Two or more of the dielectric particle groups are included, The resin molding according to claim 1 , wherein the dielectric particle groups are spaced apart from each other in a direction perpendicular to the arbitrary direction.

3. When the arbitrary direction is defined as a Y direction, a direction perpendicular to the Y direction is defined as an X direction, and a direction perpendicular to the Y direction and the X direction is defined as a Z direction, a ratio (β / α ratio) of an area β occupied by the dielectric particles when viewed in the Z-Y plane to an area α occupied by the dielectric particles when viewed in the X-Z plane is greater than 1.2 and not greater than 500; a ratio (γ / α ratio) of an area γ occupied by the dielectric particles when viewed in the X-Y plane to an area β occupied by the dielectric particles when viewed in the X-Z plane is greater than 1.2 and not greater than 500; The ratio of the dielectric particles to the XZ plane is 3 to 100% by area. The resin molded article according to claim 1 .

4. 2. The resin molded article according to claim 1, wherein a part or all of the dielectric particles have a tDa / L ratio of 0.05 to 0.9 as determined by the following measurement method. <Measurement method> A straight line is drawn in the orientation direction of the dielectric particles for the dielectric particle group, and the length Da of region a on this straight line in the orientation direction and the length L of the dielectric particle group in the orientation direction are measured. The total tDa of the lengths Da on the straight line is divided by the length L to obtain the tDa / L ratio.

5. 2. The resin molded article according to claim 1, wherein the dielectric particles have an aspect ratio of 1.0 to 200.

6. A resin molded body according to any one of claims 1 to 5, comprising a pair of electrodes and the resin molded body according to any one of claims 1 to 5 located between the pair of electrodes; The pair of electrodes faces each other in an orientation direction of the dielectric particles in the dielectric particle group.

7. A wearable device comprising the piezoelectric element according to claim 6.

8. The method for producing a resin molded body according to any one of claims 1 to 5, wherein the uncured resin is cured while applying a magnetic field in an arbitrary direction to a dispersion liquid having an uncured resin and the dielectric particles having two or more magnetic properties dispersed in the uncured resin.

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