JP3110742B2 - Magnetic recording media - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic recording medium for a toy that can record and display on a container by the action of an external magnetic field.

[Conventional technology]

Conventionally, a dispersion liquid mainly composed of a fine magnetic material, a dispersion medium and a fine particle thickener is sealed between two substrates, and the orientation of the fine magnetic material in the dispersion liquid is controlled by an external magnetic field. A magnetic panel that records and displays information on the base material by reflecting light incident on the base material from the base material or by diffusing the light into the base material, based on the contrast difference on the base material surface (for example, No. 48-41221 and Japanese Patent Publication No. 59-32796)
There is. By the way, in such a configuration, the recording displayed on the substrate is erased by returning the orientation of the micromagnetic material in the dispersion liquid to the original state again by the action of an external magnetic field.

[Problem to be solved by the present invention]

The present invention relates to a magnetic recording medium capable of performing recording and display by the orientation of the micromagnetic material in the dispersion liquid as described above. By shaking the magnetic recording medium, the orientation of the micromagnetic flakes in the dispersion liquid is returned to the original state. It is an object of the present invention to provide a small-sized magnetic recording medium capable of erasing a displayed record.

[Means for Solving the Problem] To achieve the above object, the magnetic recording medium of the present inventor forms a closed space, and at least a part thereof has a transparent or translucent portion on an inner wall surface of a container. Form a layer of a transparent or translucent dispersion liquid with a micro magnetic flake, a dispersion medium, and a fine particle thickener as main components and a yield value of ² dyne / cm ² or more, and the inside of the container is used as a magnetic space. It is a recording medium.

Since the present invention changes the direction of the micromagnetic flakes in the dispersion liquid and causes a difference in contrast between the part that reflects the light incident on the container and the part that transmits the light, the recording is displayed and erased. The dispersion liquid and the fine magnetic flakes have an excellent effect of dispersing and preventing sedimentation of the fine magnetic flakes, and the proper orientation and aggregation of the fine magnetic flakes by the magnetic action are prevented. Yield value (The yield value used in the present invention refers to the limit value of the stress required to cause the liquid to flow under the application of liquid stress, and is indicated by point A in the flow curve of the liquid shown in FIG. Is greater than ² dyne / cm ² .

The container used in the present invention must have a transparent or translucent portion in at least a part thereof and be capable of sealing the inside of the container after forming the above-described layer of the dispersion liquid on the inner wall surface of the container. . Preferably, a container body and a lid are preferably used for such work. The shape of the container may be a rectangular parallelepiped, a cylinder, a cone, a polyhedron, or the like, and the size is not particularly limited. Examples of the material include various plastics such as polystyrene, vinyl chloride, and polypropylene, and glass. Further, a handle may be attached to the container so that a child can easily hold the container.

Stainless steel flakes (trade names: SP7700, SP8500, Kawatetsu Fine Chemical Co., Ltd.)
Made), nickel flakes (trade names HCA-1, CHT, NOVAME)
T Co., Ltd.). In order to orient properly by the action of a magnetic field, the size of the fine magnetic flakes is 10 to 100 μm
Good range. The amount of the fine magnetic flakes in the dispersion liquid, which is preferably in the range of 20 to 50 μm, is set to a dispersion medium 100 described later.
It is preferably 1 to 6% by weight based on the weight%. Below this, even if a layer of the dispersion liquid is formed on the entire inner surface of the container, micro magnetic flakes are scattered in the dispersion liquid, and the characters and patterns displayed by the recording display magnet on the surface of the container are erased. For this reason, even if the container is shaken, characters or patterns cannot be completely erased because the amount of the minute magnetic flakes is not enough to tightly close the locus drawn by the recording display magnet without gaps.

As the dispersion medium, any of non-polar dispersion mediums such as organic solvents and oils can be used. Among them, aliphatic hydrocarbon solvents, particularly isoparaffin solvents, are preferred.

The thickener is used to obtain the yield value of the dispersion liquid. For example, (a) silicic anhydride, hydrous silicic acid, hydrous calcium silicate, hydrous luminous silicate, silica powder, diatomaceous earth,
Kaolin, hard clay, soft clay, benite,
Finely divided silica and finely divided silicates, such as organic benite,
(B) finely divided alumina, (c) ultrafine calcium carbonate, lightly fine calcium carbonate, ultrafine activated calcium, (d) finely divided magnesium carbonate such as hydrated basic magnesium carbonate, (e) barium sulfate, (f) bencisiso yellow,
(G) Olefin polymers such as polyethylene and low molecular weight polyethylene, and (h) olefins such as ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer and ethylene-unsaturated organic acid copolymer. Copolymer with polymerizable monomer, (li) polyalkylstyrene, (nu)
Wax, (le) metal soap, (e) fatty acid amide,
(W) dextrin phosphate fatty acid ester, (F) hydroxypropylcellulose ester, (Y) sucrose fatty acid ster, (T) acyl amino acid ster, (R) starch fatty acid ester, (SO) dibenzylidene sorbitol and the like. These thickeners can be used alone or in combination. The amount used varies somewhat depending on the type of the dispersion medium and the thickener, but a yield value of ² dyne / cm ² or more can be obtained by adding about 0.5% by weight or more to about 100% by weight of the dispersion medium.

Among these thickeners, use olefin polymers, olefin copolymers, waxes, metal soaps, acylamino acid esters, or select from olefin polymers, olefin copolymers, waxes, metal soaps, dextrin fatty acid esters. If at least one of them is used in combination with finely divided silicic acid, the yield value of the dispersion liquid does not fluctuate even when foreign matter is mixed, and good and reproducible results can always be obtained.

The yield value can be adjusted by adding a slight amount of a surfactant to the essential components of the dispersion liquid. Here, as the surfactant to be used, for example, sorbitan fatty acid ester,
Examples include polyoxyethylene alkyl ether and polyoxyethylene alkylphenol ether. The surfactants used in the present invention have no thickening effect.

The liquid for dispersing the fine magnetic flakes used in the present invention is desirably transparent, but a translucent liquid can also be used. For this reason, a translucent liquid may be prepared by selecting a thickener having a color tone, for example, barium sulfate or benzidine yellow, or adding a coloring agent such as a dye, a pigment, or a fluorescent dye separately.

As the display magnet used in the magnetic panel of the present invention, both a permanent magnet and an electromagnetic magnet can be used. These display magnets having a magnetic flux density in the range of 25 to 2000 Gauss are appropriately selected and used according to the magnitude of the saturation magnetic moment of the minute magnetic flake. Further, the contact area needs to be appropriately adjusted depending on the purpose, but usually, a contact area of 1 to 3 mm is preferable. Of course, when drawing large characters or using as stamps, it is easy to use ones of about 10 to 80 mm.

A method for manufacturing a magnetic recording medium according to the present invention will be described with reference to the drawings. Of course, the present invention is not limited to this manufacturing method.

In the present invention, first, micromagnetic flakes are added to a transparent or translucent plastic dispersion liquid containing a dispersion medium and a fine particle thickener as essential components to prepare a dispersion liquid having a yield value of ² dyne / cm ² or more. The dispersion liquid, as shown in Figure 2, the whole is poured into the container 1 of the transparent or semi-transparent rectangular container body 1 ₁ and the cover 1 ₂ combinations of box-shaped container body 1 ₁ and the cover 1 ₂ Is sealed with an adhesive or by fusing to prevent liquid leakage. Next, the container 1 is shaken to disperse the dispersion liquid in the container 1.
Is applied to the entire inner surface of the wall 2 to form a layer 3 of the dispersed liquid, the orientation of the micromagnetic flakes 4 in the dispersed liquid is parallel to the inner surface of the container, and the container is colored in the color of the micromagnetic flakes. did.

[Action]

Since the magnetic recording medium of the present invention is configured as described above, when the display magnet 5 is used to write on the wall 2 of the container 1 as shown in FIG. 3, the dispersion liquid formed on the inner surface of the wall 2 The small magnetic flakes 4 existing horizontally with respect to the surface of the wall 2 in the layer 3 are partially vertical to the surface of the wall 2 by the action of the magnetic field 6 of the display magnet 5. Orient and maintain that orientation. Therefore, as shown in FIG. 4, the light 7 incident on the wall 2 or the layer 3 of the dispersed liquid is transmitted or reflected by the layer 3 of the dispersed liquid due to the difference in the orientation of the micro magnetic flakes 4 with respect to the wall 2. Thus, recording and display can be performed on the wall 2 of the container 1 due to the contrast difference on the surface of the wall 2.

Further, in order to erase the recorded information, the container 1 is swung right and left, so that the fine magnetic flakes which are perpendicular to the wall 2 in the layer 3 of the dispersed liquid formed on the inner surface of the wall 2 are formed. 4 is oriented horizontally, the difference in contrast on the surface of the wall 2 is eliminated, and the recorded display can be erased.

〔Example〕

Embodiments of the present invention will be described. The present invention is not limited to the embodiments. Parts are parts by weight.

Example 1 97.0 parts of Isopar M (isoparaffin solvent manufactured by Esso Chemical Co., USA) as a dispersion medium and Newpole LB as a dispersant
0.5 parts of -3000 (manufactured by Sanyo Chemical Co., Ltd.) and antistatic agent ASA
0.1 parts (manufactured by Shell Chemical Co., Ltd.) and dissolved by operating for about 1 minute with a TK homomixer (wet dispersing machine manufactured by Tokushu Kika Kogyo Co., Ltd.). 200 (fine silica powder manufactured by Nippon Aerosil Co., Ltd.)
2 and 4 parts were added and stirred with a TK homomixer for 10 minutes to obtain a plastic dispersion. 8 parts of fine stainless steel flake SP7700 (manufactured by Kawatetsu Fine Chemical Co., Ltd.) was added to this plastic dispersion and mixed and dispersed to obtain a dispersion having a yield value of 27 dyne / cm ² used in the present invention.

25 g of this dispersion liquid was poured into a box-shaped container made of transparent vinyl chloride (0.5 mm thick), a rectangular container with a height of 5 mm, a length of 300 mm, and a width of 200 mm and a combination of a lid and a space. Then, the container body and the lid were adhered with an epoxy-based welding agent to seal the inside, so that there was no liquid leakage.

Shake the melter with the adhesive cured to form a layer of the dispersed liquid by attaching the dispersed liquid to the entire inner wall surface of the container,
The orientation of the minute stainless flakes in the dispersion liquid was made parallel to the wall of the container, and the entire container became silver, thereby obtaining the magnetic recording medium of the present invention.

The magnetic flux density is 1200 on the surface of the container of the magnetic recording medium of the present invention.
When drawing characters and images with a magnetic pen with a Gaussian permanent magnet attached to the tip, the minute stainless flakes at that part are perpendicular to the surface of the container, and the stainless steel flakes on the surface of the container Black letters and images with good contrast were obtained. Also, when the container was shaken lightly, the fine letters and images could be erased by the minute stainless flakes being oriented horizontally with respect to the surface of the container, making the entire surface of the container silver.

Example 2 In the same manner as in Example 1, Isopar M was used as a dispersion medium.
97.4 parts (isoparaffin solvent manufactured by Esso Chemical Co., USA) and Newpole LB-300 as a dispersant (Sanyo Chemical Co., Ltd.)
0.5 parts) and ASA-3 (manufactured by Shell Chemical Company) of antistatic agent
A plastic dispersion comprising 0.1 part and 2,0 parts of Aerosil-200 (manufactured by Nippon Aerosil Co., Ltd.) as a fine particle thickener,
6 parts of fine nickel flakes (CHT: Novamet) are added, mixed and dispersed, and the yield value used in the present invention is 13 dyne / c.
m ² of the dispersion were obtained.

15g of this dispersion liquid transparent polystyrene (1.0mm thick)
Injected so as to have a space in a container consisting of a combination of a pentagonal container body and a lid with a height of 150 mm and a side of 50 mm formed with a lid of 50 mm in height, and sealing the inside by bonding the container body and the lid with an epoxy adhesive, There was no liquid leakage.

Hereinafter, the magnetic recording medium of the present invention was obtained in the same manner as in Example 1.

The magnetic flux density is 1200 on the surface of the container of the magnetic recording medium of the present invention.
When drawing characters and images with a magnetic pen with a Gaussian permanent magnet attached to the tip, the minute nickel flakes in that part are perpendicular to the surface of the container, and the nickel surface on the container surface is Black letters and images with good contrast were obtained. Further, when the container was shaken lightly, the fine nickel flakes were oriented horizontally with respect to the surface of the container, and the entire surface of the container was made silver, so that the above-described characters and images could be erased.

Example 3 To 100 parts of the same plastic dispersion liquid as in Example 1, 8 parts of fine bright flakes (50NM30: Nihon Kagaku Kogyo KK, Ni-coated fine powder) was added, mixed and dispersed, and used in the present invention. A dispersion liquid having a yield value of 25 dyne / cm ² was obtained.

10g of this dispersion liquid is transparent polystyrene (1.0mm thickness)
Injected so as to have a space in a container consisting of a combination of a cylindrical container body and a lid having a diameter of 150 mm and a length of 20 mm formed with a lid, and bonding the container body and the lid with an epoxy adhesive to seal the inside, There was no liquid leakage.

Hereinafter, the magnetic recording medium of the present invention was obtained in the same manner as in Example 1.

The magnetic flux density is 1200 on the surface of the container of the magnetic recording medium of the present invention.
When drawing characters or images with a magnetic pen with a Gaussian permanent magnet attached to the tip, the minute bright flakes in that part become perpendicular to the surface of the container, and the silver surface of the minute bright flakes on the surface of the container Good black contrast characters and images were obtained. Also, when the container was shaken lightly, fine bright flakes were oriented horizontally with respect to the surface of the container, and the entire surface of the container was made silver, so that the above-described characters and images could be erased.

Comparative Example 1 5 parts of Isopar M (isoparaffin solvent manufactured by Esso Chemical Co., USA) as a dispersion medium, and polybutene (HV-
35: A plastic dispersion consisting of 10 parts of Nippon Petrochemical Co., Ltd., fluid rubber) and 0.1 part of antistatic agent ASA-3 (manufactured by Shell Chemical Co., Ltd.) is mixed with fine stainless flakes (SP-7700: Kawatetsu) 1 part of Fine Chemical Co., Ltd.) and mixed and dispersed to obtain a dispersion liquid having a yield value of 0 dyne / cm ² .

25 g of this dispersion liquid was poured into a box-shaped container made of transparent vinyl chloride (0.5 mm thick), a rectangular container with a height of 5 mm, a length of 300 mm, and a width of 200 mm and a combination of a lid and a space. Then, the container body and the lid were adhered with an epoxy-based adhesive to hermetically seal the inside to prevent liquid leakage.

Hereinafter, in the same manner as in Example 1, the present magnetic recording medium was obtained.

When characters and images are drawn on the surface of the container of this magnetic recording medium with a magnetic pen with a permanent magnet with a magnetic flux density of 1200 Gauss attached to the tip, the minute stainless flakes in that part become perpendicular to the surface of the container, Characters and images with poor contrast and poor resolution were obtained on the surface of the container. However, even if the stainless steel flakes were left alone for a short time, the minute stainless flakes began to flow in the dispersion liquid, and the characters and images were destroyed, and the state became difficult to read. Further, after the characters and images are obtained, even if the user shakes the container to erase the characters and images, a part of the characters and images remains.

Comparative Example 2 In Example 1, Aerosil- was used as the fine particle thickener.
A dispersion liquid having a yield value of 0 dyne / cm ² was obtained in the same manner except that 200 (fine powdered silicic acid manufactured by Nippon Aerosil Co., Ltd.) was not added.

25 g of this dispersion liquid was poured into the same container as in Example 1 so as to have a space, and the container main body and the lid were adhered with an epoxy-based adhesive to hermetically seal the inside to prevent liquid leakage.

Hereinafter, in the same manner as in Example 1, the present magnetic recording medium was obtained.

When characters and images are drawn on the surface of the container of this magnetic recording medium with a magnetic pen with a permanent magnet with a magnetic flux density of 1200 Gauss attached to the tip, the minute stainless flakes in that part become perpendicular to the surface of the container, Characters and images with poor contrast and poor resolution were obtained on the surface of the container. However, even if the stainless steel flakes were left alone for a short time, the minute stainless flakes began to flow in the dispersion liquid, and the characters and images were destroyed, and the state became difficult to read. Further, after the characters and images are obtained, even if the user shakes the container to erase the characters and images, a part of the characters and images remains.

〔The invention's effect〕

Since the magnetic recording medium of the present invention is configured as described above, by causing the orientation of the micromagnetic flakes to be perpendicular to the surface of the container by the action of a magnetic field, a sharp contrast difference is produced on the surface of the container. By shaking the magnetic recording medium and returning the orientation of the micromagnetic flakes in the dispersion liquid to the original state horizontal to the surface of the container, the record displayed on the container can be displayed. Can be erased.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between strain rate and stress for explaining the yield value of the dispersion liquid in the magnetic recording medium of the present invention, FIG. 2 is a cross-sectional view of the embodiment of the present invention, and FIG. FIG. 4 is a diagram showing a transition state of the orientation of magnetic flakes in a recording medium;
The figure shows the state of light incident on the container of the magnetic recording medium. DESCRIPTION OF SYMBOLS 1 ... Container, 1 ₁ ... Container main body, 1 ₂ ... Lid 2 ... Wall, 3 ... Layer of dispersed liquid, 4 ... Micro magnetic flakes, 5 ... Display magnet for recording, 6 ... Magnetic field .

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G09F 9/30-9/46 B42D 15/02 B42D 15/10

Claims (1)

(57) [Claims] An inner wall of a container which forms a closed space and has a transparent or translucent part at least partially, is provided with a transparent or fine particle mainly composed of a fine magnetic flake, a dispersion medium and a fine particle thickener. A magnetic recording medium which forms a layer of a dispersion liquid having a translucent yield value of ² dyne / cm ² or more and forms a space inside the container.