KR20160098930A - Magnetic sheet, and magnetic material for wireless charging having the same - Google Patents

Abstract

An embodiment of the present invention is directed to a process for the preparation of a surface-modified (i.e., surface-modified) surface- A magnetic flake including plate-shaped anisotropic particles; And a binder resin, which are obtained by laminating at least two layers of a magnetic film.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sheet and a magnetic member for wireless charging including the magnetic sheet.

An embodiment of the present invention relates to a magnetic sheet and a magnetic member for wireless charging using the same.

2. Description of the Related Art There are two types of charging methods of a secondary battery mounted in an electronic device such as a portable terminal or a video camera, namely, a contact type charging method and a non-contact type (wireless) charging method. In the contact type charging system, charging is performed by bringing the electrode of the water receiving device into direct contact with the electrode of the feeding device.

The contact type charging system has been generally used in a wide range of applications because of its simple structure. However, as the weight of various electronic apparatuses is reduced due to miniaturization and weight reduction of electronic apparatuses, The contact pressure between the electrodes is insufficient to cause a charging failure (charging error).

On the other hand, in the non-contact type (wireless) charging method, a structure for strengthening the coupling by using the plane coil and the magnetic sheet has been proposed for miniaturization and thinning. However, such a non-contact (wireless) charging method is not limited to the eddy current The inside of the apparatus is heated. As a result, there is a problem that a large electric power can not be transmitted and the charging time is long.

Particularly, it is required to develop a technique for increasing the thermal conductivity of the magnetic sheet material itself in order to solve the heat generation problem described above. As a structure for improving the thermal conductivity by orienting the magnetic powder constituting the magnetic sheet, it has been proposed to mix a thin plate-shaped powder as shown in Fig. However, even if a plate-like powder is mixed with a binder resin, the powder is dispersed in the binder resin when the powder is mixed with the binder resin, so that it is not sufficiently oriented and a desired level of thermal conductivity can not be obtained.

The embodiments of the present invention have been made to solve the problems of the prior art as described above, and it is an object of the present invention to provide a compound having a bifunctional (meth) acrylate structure formed from a composition comprising a compound having at least one nitrogen atom (N) A magnetic flake including plate-shaped anisotropic particles that are surface-modified so that the interconnector is introduced onto one region of the surface; And a magnetic sheet comprising at least two layers of a magnetic film containing a binder resin.

In order to achieve the above technical object, in the embodiment of the present invention, a spherical magnetic powder is made into a thin plate so as to be in the form of plate-shaped anisotropic particles, and a bifunctional A surface modified magnetic flake is provided to form a diffuctional linker.

In another aspect of this embodiment, a bifunctional cross-linker formed from a composition comprising a compound having at least one nitrogen atom (N) or at least one oxygen atom (O) A magnetic flake comprising surface-modified platelike anisotropic particles; And a binder resin. The magnetic sheet is obtained by laminating at least two layers of a magnetic film containing a binder resin.

According to an embodiment, a bifunctional cross-linker formed from a composition comprising a compound having at least one nitrogen atom (N) or at least one oxygen atom (O) is surface-modified to be introduced onto one region of the surface A magnetic flake comprising non-isotropic particles; And a binder resin are laminated on at least two layers to form a magnetic sheet to improve the orientation properties of the magnetic particles to obtain a magnetic film having high thermal conductivity and high electrical conductivity, It is possible to implement a product having the function of heat radiation at the same time.

1 is a conceptual diagram showing a magnetic sheet including a conventional magnetic powder.
2 is a conceptual diagram for explaining a magnetic flake.
3 is a conceptual diagram showing a magnetic film including a surface-modified magnetic flake according to the present embodiment.
4 is a conceptual diagram showing a magnetic film including a surface-modified magnetic flake according to the present embodiment.
5 is a photograph of a magnetic flake before surface modification and a surface modified magnetic flake observed with a scanning electron microscope (SEM).
Fig. 6 is a photograph of a magnetic sheet including a surface-modified magnetic flake according to the present embodiment observed with a scanning electron microscope (SEM).
7 is a photograph of a magnetic sheet including a magnetic flake which is not surface-modified with a scanning electron microscope (SEM).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that the embodiments described in the present specification and the constitutions shown in the drawings are only a preferred embodiment of the present invention, and that various equivalents and modifications can be made at the time of filing of the present application . DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the subject matter of the present invention. The following terms are defined in consideration of the functions of the present invention, and the meaning of each term should be interpreted based on the contents throughout this specification. The same reference numerals are used for portions having similar functions and functions throughout the drawings.

In this embodiment, the spherical magnetic powder is flaked so as to have a plate-like anisotropic particle shape, and a bifunctional linker is selectively formed on one area of the surface of the anisotropic particles on the plate. Thereby providing a surface-modified magnetic flake.

The spherical magnetic powder may be a metal-based magnetic powder. The magnetic powder may include at least one selected from the group consisting of Fe, Ni, Co, Mn, Al, Zn, Cu, Ba, Based on metal components such as Ti, Sn, Sr, W, Cr, Bi, Li, Y, Or a non-metallic component such as phosphorus (P), boron (B), nitrogen (N), carbon (C) or silicon (Si). In particular, the magnetic powder may be an iron (Fe) based alloy or a ferrite based alloy. (Fe-Si-Al alloy), permalloy (Fe-Ni alloy), silicon copper (Fe-Cu-Si alloy), Fe-Si Fe-Ni-Cr alloy, Fe-Si-Cr alloy, Fe-Si-Al-Ni-Cr alloy, But the present invention is not limited thereto.

Ferrite or pure iron particles can also be used. Amorphous alloys (Co-based, Fe-based, Ni-based and the like), electron soft iron, and Fe-Al-based alloys may be used. They may be oxides or partially oxidized structures. Examples of the ferrite include soft ferrite such as Mn-Zn ferrite, Ni-Zn ferrite, Mn-Mg ferrite, Mn ferrite, Cu-Zn ferrite and Cu-Mg-Zn ferrite, or hard ferrite which is a permanent magnet material have. As the Co-based oxide (Co-Zr-O-based, Co-Pb-Al-O-based, etc.), a granuler film may be used. As the Fe pure iron particles, carbonyl iron powder can be used.

Generally, the above-mentioned magnetic powder is in the form of a spherical or nearly spherical three-dimensional solid structure. However, in the present embodiment, the magnetic powder is oriented in a certain direction so as to improve the thermal conductivity and the electric conductivity, and uses an anisotropically shaped magnetic powder. Here, anisotropic means that the characteristic dimension is not the same in all directions, and is characterized in that the horizontal section has a flap structure in which a single closed curve is formed. The flaking structure is defined as a three-dimensional structure in which the longest length in the horizontal direction in the horizontal section of the magnetic powder is larger than the thickness of the magnetic powder. Thus, the anisotropic particles are, for example, fibers (substantially one-dimensional shape) or flakes (substantially two-dimensional or flat shape), that is, plate-like particles. Of these, plate-like anisotropic particles (flakes) are preferably used in this embodiment.

First, the spherical or spherical magnetic powder is subjected to flake processing so as to have a plate-shaped anisotropic particle form. The slab processing can be generally carried out by a method used in the industry, and among these, forging, rolling, punching, extrusion and the like can be selectively used. However, the method of obtaining plate-like anisotropic particles (flakes) is not limited to a great extent. Further, commercially available magnetic powder processed into plate-like anisotropic particles (flakes) may be purchased and used. The plate-like anisotropic particles (flakes) may have a ratio of the thickness to the average particle diameter (D ₅₀ ) of 45: 1 to 230: 1. The average particle diameter (D ₅₀ ) before surface modification is 30 탆 to 80 탆, and the thickness of the plate-like anisotropic particles (flakes) may be 0.4 탆 to 1.5 탆.

The surface is oxidized before selectively modifying one region of the plate-like anisotropic particles (flakes). At this time, as a method of oxidation, the surface is oxidized by a general method such as a Hummers method, which is also known as a typical oxidation method of graphene. The reason for oxidizing the surface of the plate-like anisotropic particles (flakes) is to facilitate dispersion of each flakes and to form a binding site for bonding with a bifunctional linker described later.

Thereafter, a bifunctional crosslinking agent such as an alkali chain is introduced onto the surface of the oxidized anisotropic particles (flakes) on the plate, thereby obtaining a magnetic powder which is soluble in an organic solvent and can be compounded with a polymer resin. Herein, the bifunctional interconnector means a linker that allows the polymer resin to adhere well to the magnetic powder. The bifunctional cross-linker may be formed from a composition comprising a compound having at least one nitrogen atom (N) or at least one oxygen atom (O). The bifunctional cross-linker comprising at least one nitrogen atom (N) is selected from the group consisting of 1-Ethyl-3- (3-Dimethylaminopropyl) Carbodiimide; EDC ) And ethyldiamine. ≪ / RTI > Also, the bifunctional cross-linker comprising at least one oxygen atom (O) is selected from the group consisting of diol, DiCyclohexylcarbodiimide (DCC) and 4-DiMethyiminopyridine (DMAP) ≪ RTI ID = 0.0 >

At this time, the bifunctional interconnector may be connected to the plane direction or circumferential direction of the plate-like anisotropic particles (flakes). The plane direction means a direction (F) perpendicular to the flat surface of the plate-like anisotropic particles (flakes) as shown in Fig. The circumferential direction means a direction (C) perpendicular to the plane of the plate-like anisotropic particles (flakes), that is, the circumference (side), as shown in Fig.

The magnetic sheet according to another aspect of the present embodiment is characterized in that a bifunctional cross-linker formed from a composition comprising a compound having at least one nitrogen atom (N) or at least one oxygen atom (O) A magnetic flake including plate-shaped anisotropic particles which are surface-modified so as to form a magnetic flake; And a binder resin are laminated in at least two layers. For example, a composition comprising at least one compound having a nitrogen atom (N) or an oxygen atom (O) may be any one selected from coupling reagents. In this case, the coupling reagent includes aromatic amines and phenols which are combined with the diazonium salt to form an azo compound. Examples of this include α-naphthol, β-naphthol and chromotropic acid. Since the plate-like anisotropic particles are the same as those described above, the description thereof will be omitted in order to avoid duplication.

3 is a conceptual diagram showing a magnetic film 100 including a surface-modified magnetic flake 110 according to the present embodiment. Referring to FIG. 3, the interconnector 120 including nitrogen atoms (N) among the bifunctional interconnectors may be formed to be connected to the plane direction of the magnetic flakes. That is, the interconnector 120 is formed in the direction F in FIG. 2 so as to connect the flat surface and the surface of the magnetic flake 110. [ At this time, the average particle size (D ₅₀ ) of the magnetic flakes 110 may be less than 30 탆 to less than 100 탆, and the thickness may be 0.6 탆 to 2.2 탆. The apparent density may also be 0.4 to 1.0.

The magnetic film 100 according to the present embodiment can be obtained by mixing the magnetic flakes 110 having the nitrogen atomic interconnection 120 formed on the surface thereof into the binder resin 130. The binder resin 130 is not particularly limited as long as it is homogeneously mixed with the magnetic flakes 110 and has a property capable of forming the magnetic film 100. As the binder resin 130, at least one resin such as a polyvinyl alcohol resin, a silicone resin, an epoxy resin, an acrylate resin, a urethane resin, a polyamide resin or a polyimide resin may be selected and used But is not limited thereto.

The mixing ratio of the magnetic flakes 110 to the binder resin 130 is preferably in a weight ratio of (70: 30) to (95: 5). If the blending amount of the magnetic flakes 110 is too small, the thermal conductivity may be lowered and the wireless charging performance of the finished product may be deteriorated. On the other hand, if the blending amount of the magnetic flakes 110 is too large, the amount of the binder resin 130 to be blended becomes relatively small, which makes processing difficult and durability of the magnetic sheet weakened even when processed. Further, since the shielding effect of the electromagnetic field may not be expected due to the increase of the content of the magnetic powder component, it is preferable to blend the magnetic flake 110 and the binder resin 130 at the ratio within the above range.

In addition, conventional additives ordinarily mixed with the binder resin 130 can be added, and the affinity between the magnetic flakes 110 and the binder resin 130 is improved by the addition of the additives. When such an additive is blended, the content thereof is preferably less than 2% by weight based on the total weight of the composition. Examples of such additive include a silane coupling agent, a defoaming agent, and a crosslinking agent.

The composition comprising the magnetic flakes 110 and the binder resin 130 may be made of the magnetic film 100 by the following method. The sheet may be formed by depositing a thin film on a substrate by laser vapor deposition (LVD), physical vapor deposition (PVD), or chemical vapor deposition (PVD). Examples of the method of forming a thin film by molding include a method of forming a thin film by injection, extrusion, compression, casting, blow molding or the like of a composition.

The magnetic film 100 according to the present embodiment can be manufactured by using a pressing method and a calendaring method among them in order to improve the orientation. The pressing method refers to a method of applying a composition containing a binder resin 130 and a magnetic flake 110 to a molding of a desired size and then applying pressure to a thin sheet or film shape. When a magnetic film 100 is formed by a pressing method, a magnetic sheet 100 can be formed by laminating two or more sheets of the magnetic films 100 of each sheet. The calendering method refers to a method of manufacturing a film or a sheet by arranging a plurality of heating rollers in an L-shape or a Z-shape. The calendering method is capable of producing a large number of films in a large quantity, which is more productive than other methods. Further, the magnetic film (100) produced by the calendering method can be laminated at the same time as the film formation to produce a magnetic sheet.

4 is a conceptual diagram showing a magnetic film 200 including a surface-modified magnetic flake 210 according to the present embodiment. Referring to FIG. 4, the interconnector 220 including oxygen atoms (O) in the bifunctional interconnector may be formed to be connected to the circumferential direction of the magnetic flake 210. That is, the interconnector 220 is formed in the direction C in FIG. 2 so as to connect between the distal ends of the sides of the magnetic flakes 210. At this time, the average particle diameter (D ₅₀ ) of the magnetic flakes 210 may be less than 50 μm to less than 150 μm, and the thickness may be 0.7 μm to 3.0 μm. The apparent density may also be 0.6 to 1.3.

Since the magnetic sheet produced by laminating the binder resin 220 and the magnetic film 200 is the same as described above with reference to FIG. 3, a description thereof will be omitted to avoid redundancy.

A wireless charging magnetic element according to another aspect of this embodiment comprises a bifunctional interconnector formed from a composition comprising a compound having at least one nitrogen atom (N) or at least one oxygen atom (O) A magnetic flake including plate-shaped anisotropic particles surface-modified to be introduced onto the region; And a magnetic sheet obtained by laminating at least two layers of a magnetic film containing a binder resin. It is a magnetic sheet which can improve the thermal conductivity in the width direction by orienting the plate-shaped anisotropic magnetic particles (flakes) in the horizontal direction, and further has a shielding function and a heat dissipating function of the electromagnetic field. can do.

Hereinafter, the present invention will be described more specifically by way of examples. However, the following examples are intended to aid understanding of the present invention, and the scope of the present invention is not limited to these examples in any sense.

[ Example ]

Example  1 and Example  2

Flakes are processed to obtain flake-like magnetic powder in the form of plate-shaped anisotropic particles to produce flakes. The surface of the plate-like anisotropic particles (flakes) is oxidized using a Hummus method or the like to induce bonding with a difunctional linker. At this time, coupling agents such as EDC, DCC, BOP, and HOBt can be used. The binder is mixed with the flake attached to the linker, and the magnetic sheet is pulled out by the compression method.

[Table 1]

Example  3 and Example  4

Flakes are processed to obtain flake-like magnetic powder in the form of plate-shaped anisotropic particles to produce flakes. The surface of the plate-like anisotropic particles (flakes) is oxidized using a Hummus method or the like to induce bonding with a difunctional linker. At this time, coupling agents such as EDC, DCC, BOP, and HOBt can be used. The binder is mixed with the flake attached to the linker, and the magnetic sheet is pulled out by the compression method. At this time, the mixing ratio of the flake and the binder is adjusted to measure the conductivity of the magnetic sheet according to the content of the powder.

[Table 2]

[ Comparative Example ]

Comparative Example  One

A magnetic sheet was prepared in the same manner as in Example 1 using the non-surface-modified magnetic flakes.

[evaluation]

Particles of the magnetic flakes and cross sections of the magnetic sheets obtained in Examples and Comparative Examples were observed through a scanning electron microscope (SEM), and the respective thermal conductivities were measured and shown in Table 3.

[Table 3]

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. The scope of the present invention should be interpreted based on the scope of the following claims and all technical ideas within the scope of equivalents thereof are to be construed as being included in the scope of the present invention. It is to be understood that the invention is not limited thereto.

100, 200: magnetic film
110, 210: magnetic flakes
120, 220: Interconnector
130, 230: binder resin

Claims (15)

The spherical magnetic powder is made into a flake so as to have a plate-shaped anisotropic particle form,
A magnetic flake surface-modified to selectively form a bifunctional linker on a region of the anisotropic particle surface on the plate.
The method according to claim 1,
The plate-like anisotropic grains are,
Wherein the ratio of the thickness to the average particle diameter (D ₅₀ ) is from 45: 1 to 230: 1.
The method according to claim 1,
The plate-like anisotropic grains are,
Wherein the ratio of thickness to average particle diameter (D ₅₀ ) after surface modification is from 40: 1 to 200: 1.
The method according to claim 1,
Wherein the bifunctional interconnector comprises:
A magnetic flake formed from a composition comprising a compound having at least one nitrogen atom (N) or at least one oxygen atom (O).
The method according to claim 1,
Wherein an oxide layer is formed on the surface of the plate-like anisotropic particles before the surface modification.
The method according to claim 1,
Wherein the spherical magnetic powder is a powdery magnetic powder,
A metal-based magnetic powder,
Wherein the metal is selected from the group consisting of Fe, Ni, Co, Mn, Si, Al, Zn, Cu, Ba, Ti, Sn, Sr, P, B, N, C, W, Cr, Bi, Li, Y, At least one Fe-based alloy, or a magnetic flake which is a ferrite powder.
The method of claim 6,
The Fe-
Fe-Si-Al alloys, Fe-Ni alloys, Fe-Cu-Si alloys, Fe-Si alloys, Fe-Si- Cr-Si alloy, Fe-Si-Cr alloy, and Fe-Si-Al-Ni-Cr alloy.
The present invention provides a method for producing anisotropic particles comprising a step of forming a plate-like anisotropic particle surface-modified so that a bifunctional cross-linker formed from a composition comprising at least one nitrogen atom (N) or at least one oxygen atom (O) A magnetic flake comprising; And
Binder resin;
And at least two layers of the magnetic film are laminated.
The method of claim 8,
Wherein the bifunctional interconnector comprises:
Is formed in a plane direction or a circumferential direction of the plate-like anisotropic particles, and is connected to each other between the plate-like anisotropic particles.
The method of claim 8,
The composition comprising the compound having at least one nitrogen atom,
Wherein at least two kinds of coupling reagents are selected from the coupling reagents.
The method of claim 8,
A composition comprising a compound having at least one oxygen atom,
Wherein at least two kinds of coupling reagents are selected from the coupling reagents.
The method of claim 8,
The binder resin may contain,
Wherein the magnetic sheet is at least one selected from the group consisting of a polyvinyl alcohol resin, a silicone resin, an epoxy resin, an acrylate resin, a urethane resin, a polyamide resin and a polyimide resin.
The method of claim 8,
Wherein the blending ratio of the magnetic flake to the binder resin is 70:30 to 95: 5 by weight.
The method of claim 8,
In the magnetic film,
And an apparent density of 0.6 to 1.3 or 0.4 to 1.0.
A magnetic member for wireless charging comprising the magnetic sheet according to any one of claims 8 to 14.

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