JP2011190486A - Method for forming wire made from particle of magnetic substance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a wire made from particles of a magnetic substance by coagulating magnetic particles in a fluid in a certain one direction. <P>SOLUTION: This forming method includes: coating a surface of a substrate of a nonmagnetic substance with a dispersion fluid of a magnetic substance, in which the particles of the magnetic substance are dispersed; and applying a magnetic field to the coating layer in an approximately parallel direction to cause an interaction between magnetic dipoles induced in the particles of the magnetic substance. Then, the interaction forms wire-shaped aggregates with a width larger than diameters of primary particles of the magnetic substance, in which the particles of the magnetic substance range along a direction of the magnetic field, and realizes wires formed of the wire-shaped aggregates which exist in a state of being separated from each other in the vertical direction to the direction of the magnetic field. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method of forming magnetic particles distributed in a fluid in a wire shape by anisotropic aggregation in a direction in which a magnetic field is applied. The magnetic wire in fluid produced according to the present invention is used in a wide range of technical fields as a basic technology for creating functional materials such as photonics, structural materials, sound absorbing materials, anisotropic electrodes, and anisotropic porous materials. I can do it.

In recent years, as a basic technology in various industrial fields, a technology for dispersing or arranging particle groups distributed on a substrate plane has been developed.

  Conventionally, a coating layer made of a magnetic dispersion fluid in which magnetic particles are dispersed in a fluid is formed on a non-magnetic substrate, and a particle is dispersed by applying a perpendicular magnetic field to the coating layer. The method is known. (Patent Document 1). According to this method, when a magnetic field in the vertical direction acts on the coating layer, a repulsive force acts between the magnetic particles present in the coating layer, and the particles are evenly dispersed.

Japanese National Patent Publication No. 11-514755

  However, the conventional dispersion method is applied only to a thin film and cannot be applied to a thick film. Further, the conventional dispersion method cannot be applied to other than the dispersion in the direction perpendicular to the coating layer.

  Here, the present invention provides a method for forming a wire composed of magnetic particles anisotropically aggregated by aggregating magnetic particles in a fluid in a direction parallel to the magnetic field application direction, regardless of the thickness of the thin film. Providing is an issue to be solved.

  The inventors considered that in the above conventional particle dispersion method, not only particle dispersion in a thin film but also wire formation of magnetic particles in a fluid having a thickness was possible. Based on this idea, when an external magnetic field is applied to magnetic particles existing in a three-dimensional fluid, the magnetized magnetic particles have the same magnetic pole in the horizontal direction with respect to the direction of magnetic field application, and therefore attract and act on the particles to aggregate. The inventors have found that particles having different magnetic poles in the vertical direction are dispersed due to repulsive force, and have completed the first invention.

  That is, the first invention includes a step of coating a non-magnetic substrate with a magnetic dispersion fluid in which magnetic particles are dispersed in a fluid, and a magnetic field applying step of applying a magnetic field in a substantially parallel direction to the coating layer. And forming a wire-like aggregate in which the magnetic particles are continuous in the magnetic field direction with a width larger than the primary particle diameter of the magnetic particles, and the wire-like aggregates are perpendicular to the magnetic field direction. It exists in the formation method of the wire which consists of a magnetic body particle which exists in the state away in the direction (Claim 1).

  According to a second aspect of the present invention, there is provided a method for forming a wire composed of magnetic particles according to claim 1, wherein the magnetic field is an alternating magnetic field (invention 2).

  According to a third aspect of the present invention, there is provided a method for forming a wire composed of magnetic particles according to claim 1 or 2, wherein the fluid for dispersing the magnetic particles is a curable resin composition. Item 3).

  According to a fourth aspect of the invention, in the magnetic particles according to any one of claims 1 to 3, the magnetic particles are composed of a single magnetic material or a mixture containing at least one magnetic component. It is in the formation method of the comprised wire (Claim 4).

  In a fifth aspect of the present invention, the magnetic particles are composed of nickel particles having a primary particle diameter of about 50 nm and a spherical or substantially spherical particle shape. It exists in the formation method of a wire (Claim 5).

  As described above, according to the method for forming a wire composed of magnetic particles according to the present invention, magnetic particles distributed in a fluid induce magnetic poles by the action of a magnetic field and exist at positions parallel to the magnetic field direction. The attractive force between the magnetic poles with different signs works between the particles, or the repulsive force between the magnetic poles with the same sign works between the particles that are perpendicular to the magnetic field direction. The magnetic particles that existed randomly before the magnetic field action form a wire-like aggregate in which a plurality of aggregates of primary particles are connected in parallel to the direction of the magnetic field. By repelling each other in the direction and the vertical direction, the distance is maintained without contact.

  In addition, the formation method of the wire which concerns on this invention is grasped | ascertained as a manufacturing method of a wire, when used as a process for manufacturing a wire.

It is the photograph by the optical microscope of the sample (particle concentration 0.05vol.%) After the magnetic field application in Example 1. FIG. It is the photograph by the optical microscope of the sample (particle density | concentration of 0.1 vol.%) After the magnetic field application in Example 1. FIG. It is the photograph by the optical microscope of the sample (particle density | concentration of 0.2 vol.%) After the magnetic field application in Example 1. FIG. It is the photograph by the optical microscope of the sample (particle concentration 1vol.%) After the magnetic field application in Example 1. FIG. It is a photograph by the optical microscope of the sample (particle concentration 0.05 vol.%) To which no magnetic field is applied in Example 1. It is the photograph by the optical microscope of the sample (particle density | concentration of 0.1 vol.%) In which the magnetic field is not applied in Example 1. FIG. It is the photograph by the optical microscope of the sample (particle density | concentration of 0.2 vol.%) In which the magnetic field is not applied in Example 1. FIG. It is the photograph by the optical microscope of the sample (particle concentration 1.0vol.%) In which the magnetic field in Example 1 is not applied.

  In the method of forming a wire composed of magnetic particles according to the present invention, first, a magnetic material dispersion fluid obtained by mixing a dry powder or dispersion fluid of magnetic particles with a fluid and dispersing the mixture with a medium stirring ball mill or the like. Then, a coating layer is formed in a thin film by applying to a non-magnetic substrate such as a glass plate using a coating machine such as a doctor blade.

  As the fluid for dispersing the magnetic particles, any fluid can be used as long as the magnetic particles can be dispersed. Among them, in particular, a mixture of a resin and a solvent that can be cured by heating, cooling, or light irradiation is preferably used. As the magnetic particles, any material can be used as long as it exhibits a magnetic dipole by applying a magnetic field, as long as it is ferromagnetic, paramagnetic, or diamagnetic, and any magnetic substance alone or a mixture with a non-magnetic substance. . Among these, in particular, nickel alone having a primary particle diameter of about 50 nm and a spherical or substantially spherical particle shape is preferably used.

  Then, a magnetic field is applied in a substantially parallel direction to the coating layer formed as described above, and magnetic particles are arranged in the magnetic field direction by attractive force due to the interaction of magnetic dipoles induced in the magnetic particles, While forming a wire-like aggregate, the wire-like aggregates are made to be separated from each other by repulsive force. Here, “substantially parallel” means that the magnetic field application direction can be regarded as approximately 90 ° when the direction perpendicular to the thin film is defined as zero. Further, the magnetic field to be applied is an alternating magnetic field, the frequency thereof is 0 hertz or higher, and there is no particular limitation on the cycle ratio with and without application of the magnetic field.

  The wire formed from the magnetic particles formed as described above has a wire-like structure in the resin by appropriately curing the resin composition when a resin composition that can be cured as a fluid is used. It can be fixed.

  Hereinafter, representative examples of the present invention will be shown to clarify the present invention more specifically, but the present invention is not limited by the description of such examples. It goes without saying. In addition to the following examples, various changes, modifications, improvements, and the like can be added to the present invention in addition to the specific name description described above without departing from the spirit of the present invention. It should be understood that.

  As the magnetic particles, substantially spherical nickel particles having a primary particle diameter of about 50 nm are prepared. Then, the nickel particles are mixed in an ultraviolet curable resin at a predetermined concentration in the range of 0.05 to 1%, and after being crushed by a planetary ball mill for 2 hours, ultrasonic waves are applied to the nickel particles. A coating solution was obtained. This coating solution was applied onto a glass plate with a doctor blade so as to have a film thickness of several μm, a magnetic field was applied in a direction parallel to the film surface, and ultraviolet rays were applied to solidify the resin. In addition, as a comparative example, a sample in which the resin was solidified by irradiating ultraviolet rays as it was without applying an external magnetic field to the coating layer applied in the same procedure as described above was also produced.

  An optical microscope image obtained by observing the thin film of the sample after application of the magnetic field from the direction perpendicular to the film surface is shown in FIG. 1 when the volume fraction of nickel particles in the coating solution is 0.05%, and in FIG. FIG. 3 shows the results when the volume ratio is 0.2%, and FIG. 4 shows the results when the volume ratio is 1%. From these figures, it can be confirmed that at any particle concentration, nickel particles are arranged in the direction parallel to the magnetic field by applying an external magnetic field to form a wire. It can also be seen that the wire becomes thicker as the nickel particle concentration increases. From the results when the magnetic field is not applied to the coated thin film (FIGS. 5 to 8), it can be seen that aggregated particles exist randomly in any case. Therefore, the wire-like aggregates composed of the nickel particles shown in FIGS. 1 to 4 were certainly formed by applying a magnetic field.

Claims (5)

  A magnetic material particle comprising: a step of coating a non-magnetic substrate with a magnetic material dispersion fluid in which magnetic particles are dispersed in a fluid; and a magnetic field applying step of applying a magnetic field in a substantially parallel direction to the coating layer. Forming a wire-like aggregate in which magnetic particles are continuous along the magnetic field direction with a width equal to or greater than the primary particle diameter, and the wire-like aggregates are present in a state separated from each other in a direction perpendicular to the magnetic field direction. A method of forming a wire composed of magnetic particles.   The method of forming a wire composed of magnetic particles according to claim 1, wherein the magnetic field is an alternating magnetic field.   The method for forming a wire composed of magnetic particles according to claim 1, wherein the fluid in which the magnetic particles are dispersed is a curable resin composition.   The formation of a wire composed of magnetic particles according to any one of claims 1 to 3, wherein the magnetic particles are composed of a magnetic substance alone or a mixture containing at least one magnetic substance component. Method.   5. The method for forming a wire composed of magnetic particles according to claim 4, wherein the magnetic particles are simple nickel having a primary particle diameter of about 50 nm and a spherical or substantially spherical particle shape.