JP2841291B2 - Microcapsule for magnetic display, magnetic display plate, and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microcapsule for magnetic display, a microcapsule magnetic display plate using the same, and a method of manufacturing the same. More particularly, magnetic powder in the microcapsule moves rapidly according to the operation of a magnet. A microcapsule for magnetic display to be obtained,
Furthermore, the present invention relates to a microcapsule magnetic display panel which has durability by preventing the microcapsule particles from being broken during writing, is stably held, and provides clear characters or image quality, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, various types of magnetic display methods are known. For example, Japanese Patent Publication No. 51-10959 discloses a method in which two substrates are divided into small chambers, and these small chambers are spherical. A magnetic display method in which a liquid in which magnetic powder and titanium oxide particles are dispersed is enclosed, and a magnetic field is applied to cause the magnetic powder to migrate to the surface to perform display (hereinafter, referred to as a magnetic display method).
It is called an electrophoresis method. ) And improved dispersion media for dispersing such magnetic powder and titanium oxide particles are disclosed in JP-B-57-27463, JP-B-59-31710, JP-B-59-47676, and JP-B-62-53359. Publications such as No. Among these, those which are currently in practical use are provided with a honeycomb-shaped 4 mm ³ small chamber on a supporting substrate, and a liquid in which a white pigment and magnetic powder are dispersed is injected into the honeycomb-shaped small chamber. There is a magnetic display system in which a transparent sheet is adhered and sealed. This is because the magnetic powder in the honeycomb-shaped chamber is sunk on the back surface of the display plate by moving over the entire surface of the rod-shaped permanent magnet from one end of the back surface of the magnetic display system plate to the other end, and a white pigment is formed on the front surface. In this system, the tip of a pen-shaped permanent magnet is brought into contact with the surface of a whitened display so that the magnetic powder in the contact portion is moved to the surface to form an image.

On the other hand, Japanese Patent Publication No. 54-29895 discloses a magnetic recording medium in which a microcapsule having a sensitive flake which is sensitive to a magnetic field and floats in a liquid is coated on a base material. The recording medium is applied with a magnetic field to orient the sensitive flakes in the microcapsule so that the surface is oriented in a vertical direction, and then a magnetic field is applied to a part thereof to rotate the sensitive flakes in the longitudinal direction to record. A method for producing a recording by orienting it so as to be parallel to the medium surface is described (hereinafter referred to as a deflection system). Such a magnetic display method in which the magnetic powder is made of flakes is disclosed in JP-A-63-15 / 1988.
3197, JP-A-64-19384, JP-A-1-1-1
Publications such as No. 45637 are known. Furthermore, those that disclose both the electrophoretic system and the deflection system technology,
There is JP-A-55-29880. Among them, display systems using spherical magnetic powders are characterized by specifying the size of microcapsules and improving the image quality by mixing two or more types of microcapsules having different sizes. Japanese Unexamined Patent Publication No. Hei 4-233581 is disclosed.

Among the above-mentioned known magnetic display methods, a magnetic display method using a microcapsule containing a spherical magnetic powder, as disclosed in Japanese Patent Application Laid-Open No. Hei 4-233581, in particular, provides good quality characters or images. It is excellent in that it can be obtained, but when a magnet with a weak magnetic force is used,
Not only is the image quality unclear, but also the recording or erasing speed is slow and the stability is poor. Therefore, it cannot be used for business purposes.
Also, when writing is repeatedly performed using a magnetic pen or the like, there is a problem that the microcapsule particles in the recording layer are gradually destroyed and crushed, and the sharpness is reduced. Had a problem with durability.

[0005]

Under such circumstances, there has been a demand for a microcapsule magnetic display panel satisfying the following performance. (1) The contrast is good. (2) Clear, fast writing speed and quick erasure using a normal magnet. (3) The recorded image can be stored stably. (4) The erasure can be easily erased by a magnet, and can be uniformly and quickly erased by a normal magnet. (5) Being unaffected by changes in temperature.

The inventors of the present invention have conducted various studies and studies on these points. As a result, if the magnet is strong, the magnetic powder of the surrounding microcapsules is attracted, and a clear image cannot be obtained. Under magnetic force, the above (1)
In view of the demand for microcapsule magnetic display panels of (2),
According to various studies, as a dispersion medium in a microcapsule, by selecting a combination of dispersion mediums having specific physical properties, under a weak magnetic force, that is, the moving speed of the magnetic powder with a normal magnet is fast, and It was found that a microcapsule for magnetic display in which the powder was stably retained was obtained, and the microcapsule was used. Further, among the microcapsule particles, particles larger than the average particle diameter were removed to produce a magnetic display plate. However, under a weak magnetic force, that is, with a normal magnet, a writing speed is fast, a clear character or image can be recorded, a recorded image is stable, and a microcapsule magnetic display panel having good storability is obtained. I found that.

Further, the present inventors have determined that the durability of a magnetic display panel using the microcapsules depends on the thickness and hardness of the transparent film layer and the cushion member (pressure buffer member) adjacent to the microcapsule dispersion layer. Dependent on the arrangement, the thickness and hardness of this transparent film layer acts to relieve local pressure on the microcapsules and finds that destruction of the microcapsules is prevented,
Based on this knowledge, the hardness and thickness of the transparent film surface sheet were adjusted, and the cushion member was arranged to complete the present invention. Accordingly, a first problem to be solved by the present invention is to provide a microcapsule for magnetic display in which the moving speed of magnetic powder is fast and stably held even when a magnetic force of 1100 gauss or less is used. is there. A second problem to be solved by the present invention is a microcapsule which has a high writing speed and is uniformly erased, and which can obtain clear characters and images with a high erasing speed and stability, and also has excellent durability. An object of the present invention is to provide a magnetic display panel and a method of manufacturing the magnetic display panel.

[0008]

The present invention is achieved by each of the following inventions.

[1] A microcapsule for magnetic display, wherein a dispersion medium, a magnetic powder and a non-magnetic powder in which a low-boiling solvent and a high-boiling solvent are combined is encapsulated. High-boiling solvents are compatible, and low-boiling solvents have a boiling point of 100 ° C to 150 ° C and a viscosity of 0.1 ° C.
8 cp (25 ° C.) or less, and the high boiling solvent has a boiling point of 24
0 ° C. to 350 ° C., the viscosity is 3 to 12 cps (25 ° C.), the particle diameters of the magnetic powder and the non-magnetic powder are substantially the same, and the particle diameter of the microcapsules is 800 μm or less. And a microcapsule for magnetic display having an average particle diameter of 200 to 600 μm. [2] The microcapsule for a magnetic display according to the above [1], wherein the dispersion medium contains a dispersant. [3] The microcapsule for magnetic display as described in the above item 1 or 2, wherein the dispersion medium contains a precipitation inhibitor. [4] The particle size of the microcapsules is 200 μm ± x μm or more.
4. The microcapsule for magnetic display according to any one of the above items 1 to 3, characterized in that the microcapsule is substantially formed of particles in a range of 600 μm ± x μm (x = 10 to 50). [5] An adhesive layer on the pressure buffer member, the first to fourth items
13. A microcapsule magnetic display panel comprising, in order, a dispersion layer containing the microcapsules according to any of the above items and a transparent film surface sheet. [6] The microcapsule magnetic display panel according to the above [5], wherein the pressure buffer member is a non-woven fabric. [7] The microcapsule magnetic display panel according to the above [6], wherein the thickness of the nonwoven fabric is 250 μm to 500 μm. [8] The microcapsule magnetic display panel according to the above item 5, wherein the pressure buffer member is a synthetic resin film.

[9] The microcapsule magnetic display panel according to the above item 8, wherein the synthetic resin film is any one of a polyester film, a polyethylene film, a polypropylene film, a polyvinyl chloride film and a polycarbonate film . [10] The thickness of the synthetic resin film is 50 μm to 200 μm
10. The microcapsule magnetic display panel according to the above item 8 or 9, wherein m is m. [11] The microcapsule magnetic display panel according to any one of the above items 5 to 10, wherein the thickness of the adhesive layer is 30 μm to 300 μm. [12] The microcapsule magnetic display panel according to any one of the above items 5 to 11, wherein the binder of the dispersion layer containing the microcapsules is a transparent aqueous adhesive. [13] The microcapsule magnet according to any one of the above items 5 to 12, wherein the transparent film surface sheet is any one of a polyethylene film, a polypropylene film, a polyvinyl chloride film, a polyester film and a polycarbonate. Display board. [14] The thickness of the transparent film surface sheet is 30 μm to 2
The fifth to thirteenth aspects, wherein the thickness is 50 μm .
Item 7. The microcapsule magnetic display panel according to any one of the above items. [15] The fifth aspect, wherein a colorant is contained in at least one of the dispersion medium, the microcapsule coating, the transparent film layer, the transparent aqueous adhesive or the pressure buffer member in the microcapsule dispersion layer in the microcapsules. Item 15. The microcapsule magnetic display panel according to any one of Items 14 to 14. [16] The method of manufacturing a microcapsule magnetic display panel according to any one of the above items 5 to 15, wherein the steps (1) to (8) are performed. (1) Step of adding magnetic powder, non-magnetic powder and dispersion medium to an aqueous solution of gelatin at 20 ° C. to 60 ° C. and stirring the mixture. (2) After adding an aqueous solution of gum arabic to the obtained mixed solution, lower the pH and acidify And further reducing the temperature to 20 ° C. or lower to form a gelatin / gum arabic polymer film (3) curing the polymer film to form microcapsules (4) averaging the obtained microcapsules (5) a step of dispersing the obtained microcapsules in an aqueous transparent adhesive to produce a microcapsule dispersion (6) ) Step of applying the dispersion to a transparent substrate (7) Step of drying the obtained transparent substrate to form a microcapsule dispersion coating layer (8) Applying a pressure buffer member to the surface of the obtained dispersion coating layer Setting [17] The method for producing a microcapsule magnetic display panel according to the above item 16, wherein in the step (4), the aqueous solution is concentrated to 40% to 70% in order to remove water. [18] In the step (5), the aqueous transparent adhesive is any one of an aqueous urethane resin, an aqueous aromatic polyester resin and an aqueous dispersion type urethane resin. Of manufacturing a microcapsule magnetic display panel.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a microcapsule for magnetic display, wherein a dispersion medium, a magnetic powder and a non-magnetic powder in which a low-boiling solvent and a high-boiling solvent are combined are enclosed. The low-boiling solvent and the high-boiling solvent are compatible, and the low-boiling solvent has a boiling point of 100 ° C to 150 ° C.
° C, the viscosity is 0.8cp (25 ° C) or less, and the high boiling point solvent has a boiling point of 240 ° C to 350 ° C and a viscosity of 3 to 12cps.
(25 ° C.), the particle diameters of the magnetic powder and the non-magnetic powder are almost the same, and the particle diameter of the microcapsules is 800 μm or less, and the average particle diameter is 200 μm.
６００600 μm, which provides an excellent effect that the moving speed of the magnetic powder is kept fast and stably under a weak magnetic force, that is, even with a normal magnet. In addition, by containing a dispersant in the dispersion medium, dispersoids such as magnetic powder and non-magnetic powder can be dispersed uniformly and in a short time. Further, by containing a precipitation preventive agent in the dispersion medium, it has an effect that the uniformly dispersed dispersoid is maintained in a stable state for a long time without precipitation.
In the present invention, by using the microcapsules having a particle diameter of 800 μm or less, blurring due to the destruction of large particles is eliminated, and a clear image can be obtained. Further, the particle size of the microcapsules is 200 μm ± xμm to 600 μm ± xμ.
By being substantially formed of particles in the range of m (where x = 10 to 50), clearer characters or images can be recorded.

The microcapsule magnetic display panel of the present invention comprises:
An adhesive layer, a dispersion layer containing the microcapsules according to any one of the above items 1 to 4, and a transparent film surface sheet are sequentially provided on the pressure buffering member. It has a particularly remarkable effect that the writing speed is fast and uniform, erasing speed is high, clear and stable characters and images are obtained, and the durability is excellent. In particular, since the microcapsule dispersion layer is supported by the pressure buffer member, the microcapsules in the microcapsule dispersion layer are prevented from being destroyed by the pressure during writing, and clear characters and images can be displayed for a long period of time. Thus, a microcapsule magnetic display panel having excellent durability can be obtained. Further, since the pressure buffering member used as the support member is a non-woven fabric, it acts as a pressure buffering member, protects the microcapsules, and has durability. Non-woven cloth thickness 2
When the thickness is 50 μm to 500 μm, the best pressure buffer member can be obtained. Further, by having a film-like layer on the outer surface of the non-woven fabric, the non-woven fabric can be protected and moisture can be prevented.

According to the present invention, since the pressure buffer member is a synthetic resin film, a microcapsule magnetic display panel which functions as a good pressure buffer member and has durability can be obtained. The synthetic resin film is a polyester film, a polyethylene film, a polypropylene film, a polyvinyl chloride film or a polycarbonate, or the synthetic resin film has a thickness of 50 μm or more.
When the thickness is 200 μm, the best pressure buffer member can be obtained. In the present invention, the pressure buffering member has an adhesive layer, and the thickness of the adhesive layer is 30 μm to 130 μm, which serves to protect the microcapsules from writing pressure. Since the binder of the dispersion layer containing the microcapsules is a transparent aqueous adhesive, the state of the magnetic powder and the nonmagnetic powder in the microcapsules in the microcapsule dispersion layer can be seen from the writing surface, and a clear contrast can be obtained. can get. The microcapsule magnetic display with excellent durability because the transparent film surface sheet is any one of polyethylene film, polypropylene film, vinyl chloride film, polyester film, and polycarbonate, or the transparent film surface sheet has a thickness of 50 μm to 180 μm. A plate is obtained. Further, the coloring agent is colored to an appropriate color by containing a coloring agent in at least one of the dispersion medium in the microcapsules, the microcapsule coating, the transparent film surface sheet, and the transparent aqueous adhesive or the pressure buffer member in the microcapsule dispersion layer. .

In the present invention, the following (1) to (1)
By manufacturing the microcapsule magnetic display panel according to any one of the above items 5 to 15, wherein the step (8) is performed, the writing speed is rapidly and uniformly erased, and the erasing speed is reduced. Thus, a microcapsule magnetic display panel capable of obtaining clear and stable characters and images quickly and having excellent durability is manufactured. (1) a step of adding a magnetic powder, a non-magnetic powder and a dispersion medium to an aqueous gelatin solution at 20 ° C. to 60 ° C. and stirring the mixture; and (2) adding an aqueous gum arabic solution to the obtained mixed solution and lowering the pH. Good microcapsules are formed by a process of forming a gelatin / gum arabic polymer film by making it acidic and further lowering the temperature to 20 ° C. or less. (3) a step of curing the polymer film to form microcapsules; and (4) removing the particles having a size exceeding the average particle diameter of the obtained microcapsules to make the upper limits uniform and to remove moisture. Step (5) Step of dispersing the obtained microcapsules in an aqueous transparent adhesive to produce a microcapsule dispersion, (6) Step of applying the dispersion to a transparent film surface sheet, and (7) Obtaining Drying the transparent substrate to form a microcapsule dispersion coating layer and (8) providing a pressure buffer member on the surface of the obtained dispersion coating layer

In the step (4), a microcapsule dispersion layer having an appropriate viscosity can be formed by concentrating the aqueous solution to 40% to 70% in order to remove water. In the step (5), the aqueous transparent adhesive is one of an aqueous urethane resin, an aqueous aromatic polyester resin and an aqueous dispersion type urethane resin, so that the microcapsules having excellent durability in cooperation with the pressure buffer member. A magnetic display panel can be manufactured. Further, the viscosity of the microcapsule dispersion is preferably used at a viscosity suitable for coating on a substrate. The viscosity varies depending on the temperature of the four seasons and various coating conditions.
After adjusting to 5,000 cP, the viscosity-adjusted dispersion is applied to a substrate and dried to form a microcapsule dispersion layer, whereby a clearer character or image can be recorded. Further, by adhering a pressure buffer member, that is, a sheet having an adhesive layer to the surface of the dispersion coating layer as in the step (8), voids (bubbles) can be formed in the uneven portions on the surface of the microcapsule dispersion layer. Adhesive does not penetrate and a bonded portion is obtained. Further, in the step (8), when the pressure buffering member is a transparent plastic film or a hard or soft film, the microcapsules that can be used in combination with a device that uses a light source to brighten the back are used. A magnetic display panel can be manufactured.

Hereinafter, the present invention will be described in more detail. The low boiling point solvent used for the magnetic capsule of the present invention has a boiling point of 100 ° C. to 150 ° C. and a viscosity of 0.8 cp.
(25 ° C.) The following are used. Preferred such low-boiling solvents are toluene, xylene,
Ortho-meta-para-xylene, ethylbenzene, ethylcyclohexane, 2-hexane and the like can be mentioned. These low boiling solvents may be used alone or in combination of two or more.

The high boiling solvent used in the present invention has a boiling point of 2
Those having a temperature of 40 ° C. to 350 ° C. and a viscosity of 3 to 12 cp are used. Preferred high-boiling solvents include dodecylbenzene, dipentylbenzene, diphenyl ether, benzyl benzoate, diethyl phthalate and the like. These high boiling solvents may be used alone or in combination of two or more. Further, it is preferable that these low-boiling solvents and high-boiling solvents have compatibility, and such combinations include toluene and dodecylbenzene, xylene and dipentylbenzene,
Preferred are ethylbenzene and diphenyl ether, ethylcyclohexane and benzyl benzoate, and the like.

In the present invention, the low boiling solvent having a boiling point of 1
The reason why the viscosity is limited to that of 00 ° C. to 150 ° C. and the viscosity is 0.8 cp or less is that if the boiling point is less than 100 ° C., the viscosity decreases, the dispersion stability deteriorates, the dispersoid precipitates, and the volatility of the solvent is high. Volatilizes and emanates from the microcapsules,
Cannot be sealed for a long time. The boiling point is 150
Above ° C, the boiling point of the high boiling point solvent is approached and therefore the dispersoid moves less with respect to the magnet. It is preferable to use a low boiling point solvent having a viscosity of 0.8 cp or less,
Exceeding 0.8 cp is not preferable because the movement of the dispersoid decreases in relation to the viscosity of the high boiling point solvent. On the other hand, the reason why the boiling point of the high boiling point solvent is limited to 240 ° C. to 350 ° C. and the viscosity is 3 to 12 cp is that if the boiling point of the high boiling point solvent is less than 240 ° C., not only the dispersion stability of the dispersoid becomes poor, but also The degree of divergence outside the capsule increases, which is not preferable.
On the other hand, if the boiling point of the high boiling point solvent exceeds 350 ° C., the viscosity becomes high and the movement of the dispersoid becomes worse, so that a good microcapsule magnetic display panel cannot be obtained. When the viscosity of the high boiling point solvent is less than 3 cp, the viscosity becomes low due to the relationship with the low boiling point solvent, and the dispersoid precipitates. In addition, the viscosity of the high boiling point solvent is 12c.
When p is exceeded, the movement of the dispersoid becomes worse. In the present invention, as described above, the dispersion and retention of the dispersoid can be favorably adjusted by the specific combination of the low-boiling solvent and the high-boiling solvent.

In the present invention, the dispersing agent for dispersing the magnetic powder and the like includes polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and a mixture of anionic aliphatic ester. And polycarboxylic acid amine salts. The addition amount of the dispersant may be an amount usually used as an addition amount of the dispersant, and the addition amount is 0.5% by weight to 10% by weight, preferably 1.0% by weight to 3.0% by weight. It is. If the amount of the dispersing agent is less than 0.5% by weight, a sufficient dispersing effect cannot be obtained, and if it exceeds 10% by weight, the viscosity of the dispersing medium becomes high and the properties of the dispersing medium are impaired.

In the present invention, when a low-boiling solvent and a high-boiling solvent are mixed as a dispersion medium, the mixing ratio of these solvents is 20% by weight of the low-boiling solvent with respect to the low-boiling solvent.
It is preferable to mix at a ratio of ２５０250% by weight, more preferably at 50% by weight to 150% by weight. If the proportion of the high-boiling solvent to the low-boiling solvent is less than 20% by weight, the emission of the low-boiling solvent cannot be prevented, and if it exceeds 250% by weight, the movement of the magnetic powder becomes poor. Further, as precipitation inhibitors, silicic anhydride, hydrous silicic acid, silicates (sodium silicate, potassium silicate, aluminum silicate, calcium silicate, etc.), fine alumina powder, silica powder, diatomaceous earth, carion, hard clay, soft clay, bentonite, Examples include ultrafine calcium carbonate, ultrafine activated calcium carbonate, calcium bicarbonate, hydrated basic magnesium carbonate, barium sulfate, and benzidine yellow. These may be used alone or in combination of two or more. The amount of the suspending agent added to the dispersion medium varies depending on the type of the dispersion medium, but the suspending agent is 0.2 to 5% by weight, preferably 0.4 to 2% by weight, based on the dispersion medium. % By weight. If the amount of the precipitation inhibitor is less than 0.2% by weight, there is no precipitation preventing effect, and if it exceeds 5% by weight, the movement of solid particles such as magnetic powder is hindered.

As the magnetic powder used in the present invention, those usually used in this technical field may be used, such as black iron oxide, porous iron oxide, manganese dioxide-containing iron oxide,
Fine particles of chromium dioxide, ferrite, iron or nickel,
A magnetic powder that has not been subjected to an affinity treatment, such as an iron-nickel alloy, may be mentioned, and a synthetic magnetic iron oxide is particularly preferable. These are 1
Species or a mixture of two or more kinds may be used. Examples of commercially available products include Todacolor KN-320 (magnetite manufactured by Toda Kogyo Co., Ltd., Tarox BL-50 (synthetic iron oxide manufactured by Titanium Kogyo Co., Ltd.), etc. Preferred is Fe ₃ O ₄ . The particle size of the magnetic powder is preferably 10 μm or less in diameter, preferably 0.1 μm to 5 μm, and more preferably 0.1 μm.
０．８0.8 μm. Further more preferably, it is 0.1 μm or more.
It is preferable that the particle size is 0.5 μm and contains 70% or more of particles of 0.2 μm to 0.3 μm. Since the magnetic powder that has been subjected to the affinity treatment reduces the ability of the precipitation inhibitor,
Not preferred.

In the present invention, the particle size of the magnetic powder is 10 μm
Exceeding the range is not preferable because the sharpness of characters and the like deteriorates.
If the thickness is less than 0.1 μm, the speed of writing and erasing becomes considerably slow . The nonmagnetic powder to be used in or present invention, titanium dioxide, lithopone, zinc white, white lead, are zinc sulfide, titanium oxide may be either anatase or rutile type. Preferably, rutile type titanium oxide is preferable in terms of hiding power. All of these are preferably those having a small specific gravity. Further, it is preferable that the oil absorption amount (oil absorption means that the solvent is absorbed inside the particles) is relatively high. The particle size of the non-magnetic powder is not particularly limited as long as it can be sufficiently dispersed, but is 0.1 μm to 1 μm, preferably 0.1 μm to 0.5 μm. If the particle size of the magnetic powder is large and the particle size of the titanium oxide is small, the movement of the magnetic powder is fast, but the blackness is not high, so the contrast is poor, and the particle size of the magnetic powder is small and the particle size of the titanium oxide is small. If the size is large, blackness appears and the contrast is improved, but the movement of the magnetic powder is undesirably deteriorated. From these facts, it has been found that the magnetic powder and the non-magnetic powder need to be present with the same particle size.

A coloring agent can be added to the dispersion medium of the microcapsules used in the present invention or to the gelatin coating of the capsules, whereby the back or background of the magnetic display panel can be colored in various colors. . Dyes and pigments are usually used as the coloring agent. Examples of these dyes or pigments include dyes such as methylene blue, Congo Red, and Benzo Yellow TZ, and oil blue, oil green, oil yellow, and benzidine yellow.

The average particle size of the microcapsules for magnetic display of the present invention is from 200 μm to 600 μm, preferably from 200 μm to 400 μm. If there are many large microcapsules having an average particle size of 600 μm or more, the microcapsules are destroyed during writing, the number of capsules die, the sharpness decreases, and the durability decreases,
The above range of 200 μm to 600 μm is preferable. Therefore, the particle size of the microcapsules for magnetic display is 200 μm.
± x μm to 600 μm ± x μm (where x = 10 to 5
By substantially forming the particles in the range of 0), a very thin magnetic display plate is formed, and characters and images formed thereon become clearer.

The microcapsule for magnetic display of the present invention comprises:
After dispersing in a binder or a dispersion medium, the substrate is coated to form a microcapsule magnetic display member, and characters and images are formed using a magnetic field. Various methods for forming characters and images using a magnetic field on the magnetic display member are known in this technical field, and any method can be used.

In the present invention, when a microcapsule magnetic display plate is manufactured and recorded or erased using a magnet,
When a magnet of 100 gauss or more is used, the display speed or erasing speed is fast, and clear characters or images can be recorded and erasing can be performed quickly. When used, the display speed or the erasing speed is high, and a clear character or image can be recorded and the erasing can be performed quickly. An excellent effect is obtained when recording a character or an image. A preferable effect is obtained at 700 to 700 gauss, more preferably 1000 gauss to 800 gauss, and even a weaker magnet can be used at all depending on the purpose of use.

For erasing characters or images on the recording surface,
Even if a magnet having a weak magnetic force, for example, 200 gauss to 300 gauss is used, an excellent effect is obtained in that the erasing speed is sufficiently fast and a uniform erasing surface can be obtained. Accordingly, a microcapsule for magnetic display which is more technically and economically superior than the conventional one, and a microcapsule magnetic display panel using the same can be obtained. In addition, the method for coating the microcapsules on the substrate can be performed by using a usual coating method, for example, brush coating, roller coating, screen printing, air curtain, dip coating, or the like.

Examples of the material used for the pressure buffering member used in the magnetic display panel of the present invention include a nonwoven fabric having a thickness of 50 μm to 500 μm, a synthetic resin film, and an elastic member (for example, a rubber material, a cork material, a foamable material, etc.). ) And UV curable resins are used. An adhesive layer is provided on the inner surface of the nonwoven fabric, synthetic resin film or elastic member, that is, the surface in contact with the dispersion layer containing the microcapsules, and the thickness of the adhesive layer is preferably 30 to 130 μm. When an ultraviolet curable resin is used, it can be applied immediately to the surface of the dispersion layer containing the microcapsules in a liquid state, and then irradiated with ultraviolet rays to cure the liquid ultraviolet curable resin to form a pressure buffer member. Another method when using an ultraviolet-curable resin is to apply the ultraviolet-curable resin in a liquid state to the surface of the dispersion layer containing the microcapsules, place a synthetic resin film thereon, and irradiate with ultraviolet light. Thus, the liquid ultraviolet curable resin is cured so that the dispersion layer and the synthetic resin film including the microcapsules are integrated to form a pressure buffer member. The thickness of the ultraviolet curable resin layer is preferably from 50 μm to 300 μm.

The adhesive for the adhesive layer of the nonwoven fabric is not particularly limited, and a wide variety of adhesives can be used. For example, natural rubber, isoprene rubber, styrene / butadiene rubber, styrene / butadiene block copolymer, styrene / isoprene block copolymer, butyl rubber, polyisobutylene, silicone rubber, polyvinylisobutyl ether, chloroprene rubber, nitrile rubber, graft rubber, and regeneration It is produced by adding an adhesion-imparting agent, a softening agent, an anti-aging agent, a filler and the like to an elastomer such as rubber. Usually, various adhesives such as natural rubber, styrene-butadiene, polyisoprene, acrylic, and silicone are preferable.

The material of the nonwoven fabric includes natural fibers such as cotton, flax, jute, wool and silk; cellulosic fibers such as rayon and acetate; polyamide fibers such as nylon; chlorinated hydrocarbon fibers such as vinylidene; Synthetic fibers such as polyurethane fibers and polypropylene fibers are preferably used. Non-woven fabric produced using these fibers,
Various nonwoven fabrics manufactured by a known method used for ordinary nonwoven fabric production are used, and are not particularly limited by the type of the nonwoven fabric.

In the present invention, when a synthetic resin film having an adhesive layer is used as the pressure buffering member, the adhesive layer plays an important role. That is, a synthetic resin film having an adhesive layer is adhered to the microcapsule layer. At this time, an adhesive or an adhesive method is preferred in which the adhesive of the adhesive layer adheres to the surface of the microcapsule to form no void.
As a result, the flexibility of the magnetic display panel (strength against bending)
Not only can be improved, but also the protection of the microcapsules can be made sufficient. Further, the thickness of the adhesive layer cannot be made too large because of the quality of the erasure of the recording drawn simultaneously with the protection of the microcapsules. Therefore, the thickness of the adhesive layer is preferably 30 μm to 130 μm. If the thickness of the adhesive layer is less than 30 μm, the protection of the microcapsules is not sufficient and the microcapsules may be broken by the pressure during writing. Even if the thickness exceeds 130 μm, sufficient protection can be obtained,
On the other hand, it is not preferable because the erasing of the record by the magnet becomes insufficient, and it is economically unfavorable because a strong magnet needs to be used as the erasing magnet.

In the present invention, the thickness of the synthetic resin film is preferably 50 μm to 200 μm with respect to the thickness of the adhesive layer. Good, but need not be thin. Examples of the adhesive constituting the adhesive layer used in the present invention include various adhesives such as natural rubber, styrene-butadiene, polychloroprene, polyisoprene, polyurethane, acrylic, and silicone. The synthetic resin film used here is
Usually, a polyethylene film, a polypropylene film, a vinyl chloride film, a polyester film, a polycarbonate film, and the like, which are the same as those used on the back surface of the nonwoven fabric, are used.

The microcapsule magnetic display panel of the present invention comprises:
After producing a microcapsule containing a magnetic powder, a non-magnetic powder and a dispersion medium, this is dispersed in an aqueous emulsion adhesive. The obtained dispersion is applied to a transparent film substrate (to become a transparent film layer) and then dried to form a microcapsule dispersion coating layer. The transparent film layer may be any material as long as it acts to relieve the local pressure on the microcapsules and prevents the microcapsules from being broken. Relieving the local pressure on the microcapsules means that the transparent film layer is not dented or scratched against writing pressure and the flexibility is not impaired. Therefore, the hardness of the transparent film layer may be adjusted by adjusting the hardness of the resin of the transparent film layer and the thickness of the resin of the transparent film layer by using a predetermined material. As the transparent film layer, a transparent film such as polyester and polyethylene is used, but is not limited thereto. The thickness of the transparent film is 30 μm to 250 μm, preferably 50 μm to 180 μm.

The method for producing a microcapsule magnetic display panel of the present invention is specifically obtained by the following production method. That is, the steps (1) to (8) are performed, and (1) a mixture of a magnetic powder, a non-magnetic powder, and a dispersion medium is added to a 40 ° C. to 60 ° C. aqueous gelatin solution and stirred. Process, whereby the most preferred method of coacervation is obtained.

(2) Step of adding an aqueous solution of gum arabic to the obtained mixed solution, making it acidic by adjusting the pH to 5 or less, and further lowering the temperature to 20 ° C. or less to form a gelatin / arabic gum polymer film. (3) curing the polymer film to form a gelatin-coated microcapsule; and (4) removing the microcapsules having a size exceeding the average particle size of the gelatin-coated microcapsule for magnetic display obtained above. By doing so, it is possible to increase the application density of the microcapsules by adjusting the upper limit and removing water from the obtained microcapsule slurry in the step of removing water. In this step, the microcapsules are adjusted to a predetermined particle size or the average particle size of the microcapsules is used and those having a size exceeding the average particle size are removed. As in the latter case, a net is used to remove those having a size exceeding the average particle size of the microcapsules, and only those which pass through the net are selected. By aligning the upper limit of the microcapsules, it is possible to apply the microcapsules to a certain thickness, to prevent inactivated capsules (capsules that are broken and cannot participate in recording or display), and provide a clear image on the magnetic display panel. Preferred for obtaining indication.

(5) A step of producing a microcapsule dispersion by dispersing the obtained microcapsules in an aqueous transparent emulsion-based adhesive. This dispersion is preferably coated with an appropriate viscosity at the time of coating. In the process, the viscosity of the dispersion is adjusted to 15,000 cP to 35,000 cP. Here, the substance for adjusting the viscosity of the microcapsule dispersion, that is, as a viscosity modifier, sodium alginate, polyvinyl alcohol, modified sodium polyacrylate, modified polyacrylic acid emulsion, modified polyacrylic acid sulfonate, and the like, Particularly preferred are sodium alginate and polyvinyl alcohol. The addition ratio of the viscosity modifier depends on the temperature of the four seasons and the state of the dispersion.
0% by weight is used. When the viscosity of the microcapsule dispersion is less than 15,000 cP, the coating film is cracked and characters and the like become unclear. On the other hand, when the viscosity exceeds 35,000 cP, the coating film is not uniformly coated and becomes uneven, which is not preferable.

(6) a step of applying the dispersion to a transparent film surface sheet; and (7) a step of drying the applied transparent film surface sheet to form a microcapsule dispersion coating layer. Preferably, a transparent film such as polyester or polyethylene is used, but is not limited thereto. The thickness of the film is 30 μm to 250 μm,
Preferably it is 50 μm to 200 μm. Such a film can be coated with the microcapsule dispersion by a usual coating method such as brush coating, roller coating, screen printing, air curtain, or dip coating. After application, the coating is dried. The drying temperature may be in a range usually used in this technical field, for example, 40 ° C to 120 ° C, preferably 50 ° C.
９０90 ° C. Further, the drying time is usually preferably from 10 minutes to 2 hours. More preferably, 30 minutes to 50 minutes are preferable. As a drying method, warm air drying or convection drying is preferable. The dry thickness of the microcapsule dispersion is 4
00 μm to 600 μm is preferred.

(8) A step of providing a pressure buffer member on the surface of the obtained dispersion coating layer. The sheet for the pressure buffer member is not particularly limited, but is preferably a polyester film (hereinafter referred to as a PET film). ). The PET film is adhered on the microcapsule dispersion coating layer coated on the PET film. The thickness of the film is preferably 50 μm to 200 μm.

The microcapsule magnetic display panel or magnetic display member obtained by the manufacturing method of the present invention forms a character or an image using a magnetic field. Various methods for forming characters and images using a magnetic field on the magnetic display member are known in this technical field, and any method can be used. The magnetic display member obtained by the present invention can be used for various purposes, for example, a picture book for infants, a toy for infants, a character practice device, various game boards, a penmanship board, a memo board, and a meeting board. Blackboards, various information boards in clean rooms,
Examples include an electronic bulletin board and a display panel of a personal computer.

[0039]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the examples are for explaining the present invention, and the present invention is not limited thereto.

Example 1 A microcapsule for magnetic display of the present invention is schematically shown in a sectional view in FIG. 1, and FIG. 2 shows a microcapsule 1 for producing a dispersion of the microcapsule 1 of the present invention. It is a flow sheet. FIG. 3 is a schematic sectional view showing a coating apparatus for manufacturing a microcapsule magnetic display panel. The microcapsule 1 shown in FIG. 1 was manufactured by the following method in accordance with the flow sheet shown in FIG. 2, and the microcapsule magnetic display panel was manufactured using the coating apparatus shown in FIG.

1, 2 and 3, a microcapsule 1 has a capsule coating 2 made of gelatin, into which a magnetic powder 3 and a non-magnetic powder 4 are dispersed and enclosed in a dispersion medium 5. ing. The following components are placed in a temperature-adjustable tank 6 equipped with a stirrer 7, and microcapsules are manufactured while adjusting the temperature, pH, and the like as described below. This microcapsule 1 is used as magnetic powder 3
Ferrite powder particles having an average particle diameter of 0.3 μm (trade name: Talox BL-50, obtained by pulverizing Titanium Industry Co., Ltd.) 2% by weight and non-magnetic powder 4 having an average particle diameter of 0.26
μm white titanium oxide powder (trade name TIPAQUE,
R-820, manufactured by Ishihara Sangyo Co., Ltd.) 11.6% by weight as a high-boiling solvent, 40% by weight of dibutyl phthalate, and 45% by weight of toluene as a low-boiling solvent.
5% by weight and Dappo SN-35 as an antifoaming agent
0 (silicone, manufactured by San Nopco) and 0.5% by weight of finely divided silica (Aerosil, manufactured by Nippon Aerosil Co., Ltd.) as a suspending agent, and as a dispersant, Nopcosanto K963 (sodium polycarboxylate) A surfactant (manufactured by Sannobue Co., Ltd.) (0.7% by weight) was added and dispersed.

Next, the gelatin concentration adjusted to pH 6: 1.
A 1.8 % aqueous solution of gum arabic was added to the 8 % aqueous solution to prepare an aqueous solution for the microcapsule membrane, the temperature was raised to about 50 ° C., the pH of the aqueous solution was adjusted to 5, and the magnetic powder prepared in advance was prepared. 3 and a dispersion of the non-magnetic powder 4 were added, and the mixture was stirred so that the dispersion droplets became about 300 μm. After the desired dispersed droplets are obtained, the temperature of the system is cooled and then 10 ° C.
The gelatin / gum arabic polymer film precipitated on the interface of the dispersed droplets by cooling to a temperature was gelled, and an aqueous solution of glutaraldehyde at a concentration of 25% was added to harden the polymer film to obtain gelatin microcapsules 1. Was. The microcapsules 1 thus obtained were removed through a mesh to remove particles having a size exceeding 600 μm to obtain particles having a size of 600 μm or less. This microcapsule has a particle size of 600 μm or less and contains 85% of particles of 200 μm to 300 μm.

The obtained microcapsule slurry solution 7
Numeral 1 is introduced into the filtering device 8, and the filter 81 removes particles 85 larger than 600 μm and removes moisture to accumulate particles smaller than 600 μm on the filter 82. Water flows out of the faucets 9a, 9b, 9c, respectively. The filter 81 has a hole 83 which does not allow particles 85 larger than 600 μm to pass through, and the filter 82 has a hole 84 which allows small particles 87 to pass. Then, the obtained group of microcapsules 86 is introduced into a container 10 with a stirrer 11 in order to form an ink 18 for application, and an aqueous urethane resin solution as an aqueous binder 72 is added thereto, and the mixture is sufficiently stirred to form an ink. An object 18 is formed. The obtained coating ink 18 is applied using an application device as shown in FIG. The viscosity of the ink material for application 18 is 28,000 cP.

In FIG. 3, (a) is a coating device used in a coating process. In this coating device, a belt conveyor 17 is rotated by rollers 15 and 16 in an arrow direction. Suction member 2 moving up and down from sheet supply device 29
At step 8, the transparent film sheet 21 is sucked, conveyed onto the belt conveyor 17, penetrates into the lower part of the already supplied sheet 21, and the front part is superimposed. The object 18 is applied by the application roller 14 to form the coating layer 20. The coated cover sheet 23 is stored in the storage rack 22 and
a, 23b,... 23h. FIG. 3B shows a drying step. After the storage rack 22 is stored in the drying chamber 25, the storage rack 22 is dried with hot air of 70 ° C. for 40 minutes. FIG. 3 (c) shows a laminating step. The microcapsule magnetic display panel I is obtained by bonding a PET film as an adhesive to the coated surface of the coated sheet 23 obtained as described above as a pressure buffer member 24. Was prepared.

FIG. 4 is a sectional view showing a microcapsule magnetic display panel of the present invention. In FIG. 4, the magnetic display panel I
Has a microcapsule dispersion layer 20 on a plastic film serving as a pressure buffering member 24 and a recording sheet 21 thereon.
Have large particles 31, 3 as microcapsules
2. Medium-sized particles 33 and 34 and small particles 35 are appropriately arranged. Instead of the plastic film 24, glass fiber, glass, paper, or other hard sheet or soft flexible film having sufficient strength to hold the microcapsule coating layer 20 can be used.

Next, a method of displaying characters on the microcapsule magnetic display panel I of the present invention will be described.
FIG. 5 is a cross-sectional view showing a method of displaying characters on the microcapsule magnetic display panel I obtained by the present invention.
5 shows a state where the back surface of the magnetic display plate I is scanned by a magnet, and FIG. 5B shows a state where a letter E is written on the surface using a bar magnet. First, the back side of the magnetic display panel I is scanned with a sheet magnet (200 gauss) 81 having a weak magnetic force in the direction of the dotted line as shown in FIG. 3 is moved or migrated to the pressure buffering member 24 side (erasing operation). As a result, the magnetic powder 3 in the capsule exists on the side of the pressure buffer member 24 of the magnetic display panel I, and is replaced with the magnetic powder 3 on the recording sheet 21 side (transparent sheet) on the surface of the magnetic display panel I. Since the non-magnetic powder 4 is present, the surface of the magnetic display panel I has a white color, which is the non-magnetic powder 4. Next, when a character was written on the surface of the magnetic display panel I obtained as shown in FIG. 5B using a bar-shaped magnet 82 as a writing instrument, a clear character E was obtained.

Here, when the magnetic display panel I of the present invention and a comparative magnetic display panel (commercially available) were compared under the same conditions, the magnetic display panel I of the present invention and the comparative magnetic display panel were compared. When the lines were written at a slow speed, both lines could be drawn, but the comparative magnetic display panel was unclear, while the magnetic display panel I of the present invention was sharp. Further, when lines were written on the magnetic display plate I of the present invention and the comparative magnetic display plate at a speed higher than the normal writing speed, almost no lines could be drawn on the comparative magnetic display plate. Plate I was able to draw clear lines.

Next, when the erased state of the characters drawn on the recording sheet was tested under the same conditions with the magnetic display panel I of the present invention and the comparative magnetic display panel, the magnetic display using a 200 gauss sheet magnet was performed. When the back surface of the plate was slowly scanned, the magnetic display plate I of the present invention and the magnetic display plate of the comparative example were sufficiently white without being spotted by one erasing operation.
When performing the erasing operation with a 0 gauss sheet magnet at a high scanning speed, the magnetic display plate I of the present invention shows that the magnetic powder reacts quickly to the magnet and the characters on the recording sheet surface are quickly However, in the comparative magnetic display panel, the reaction of the magnetic powder to the magnet was insufficient, and the character was not sufficiently erased by one scan, and a uniform color surface could not be obtained.

Example 2 In the dispersion medium in the microcapsules described in Example 1, a combination of a low-boiling solvent and a high-boiling solvent shown in Table 1 was used. Microcapsule magnetic display panel I
Was prepared. The scanning speed and surface properties, the writing speed, the sharpness of characters and the durability of the magnetic display panel I were tested. Table 4 shows the obtained results. In Table 1, ○ indicates good; Δ indicates somewhat good; × indicates poor.

[0050]

[Table 1] As is clear from Table 1, in the magnetic display panels manufactured using the microcapsules of the present invention, excellent effects were obtained in each case. On the other hand, in the case of using the conventional dispersion medium, the surface properties of the magnetic display panel are not sufficient, the scanning speed, the writing speed, etc. are poor, and the characters drawn on the display panel are slightly unclear. there were. Therefore, the retention, movement and erasure of the magnetic powder were not sufficient.

Example 3 According to the method of Example 1, the size of the microcapsules was 200 μm,
Microcapsules with larger particles removed, also 3
Microcapsules with a particle size of more than 400 μm, centered on 00 μm, 500 micrometer, centered on 400 μm
microcapsules with particles larger than μm removed, 50
Microcapsules each having 0 μm as a center and particles larger than 600 μm removed were manufactured, and magnetic display plates were manufactured in the same manner as in Example 1. For each, the scanning speed and surface property, writing speed and sharpness of characters were measured. Tested. In the magnetic display panels manufactured using the microcapsules of the present invention, excellent effects were obtained. On the other hand, in the case of producing microcapsules without removing particles larger than the particle size used,
The surface properties of the magnetic display panel were not sufficient, and the characters drawn on the display panel were somewhat unclear.

Example 4 A microcapsule having a particle size of 180 μm to 240 was selected,
A magnetic display panel was manufactured in the same manner as in Example 1. Next, when a character was written on the surface of the magnetic display panel using a bar-shaped magnet at a speed higher than a normal writing speed, a clear character was obtained.

Example 5 The microcapsules produced in Example 1 were dispersed in a transparent binder of an aqueous urethane resin, and the dispersion was treated with an aqueous coloring pigment, Neuractish (manufactured by Dainichi Seika Kogyo Co., Ltd.). Except for adding, a magnetic display panel was manufactured in the same manner as in Example 1. By adding a pigment in this manner, the magnetic display plate can be colored, and similarly, can be colored in various colors.

Embodiment 6 In the present invention, a microcapsule magnetic display panel shown in a sectional view in FIG. 6 was manufactured. In FIG. 6, the microcapsule magnetic display plate II
Has a sheet 60 of the pressure buffer member 24 and a microcapsule dispersion layer 20 thereon, and is further covered with a transparent layer 21. The pressure buffer member 24 and the transparent layer 21 are adhered to the microcapsule dispersion layer 20 with an adhesive 62. As the microcapsule 1 for magnetic display used in the present invention, the microcapsule manufactured in Example 1 was used. The microcapsule magnetic display panel II of the present invention comprises a microcapsule dispersion layer having a thickness of 600 μm, which is formed by applying a coating ink material comprising a microcapsule dispersion on a polyethylene terephthalate transparent film sheet 21 having a thickness of 120 μm and drying. After forming 20, a non-woven fabric 63 having a thickness of 500 μm is formed as a sheet 60 of the pressure buffer member 24 on the coating surface. At this time, the adhesive 62 has an uneven surface on the microcapsule dispersion layer 20, and the concave portion 62a is formed at the contact portion between the microcapsules. Penetrates and is firmly adhered. The microcapsule magnetic display panel II obtained in this way is strong in flexibility, and when writing on the magnetic display surface using this magnetic display panel II, not only clear characters were obtained, but also
Even after repeated writing, there was no abnormality in the microcapsule particles in the microcapsule dispersion layer, and no crushed microcapsule particles were found. Therefore, durability against repeated use was good.

[Seventh Embodiment] As in the sixth embodiment, FIG.
Micro-capsule magnetic display panel III shown in cross-section
Was prepared. This microcapsule magnetic display panel III
After forming the microcapsule dispersion layer 20 having a thickness of 600 μm, the sheet of the pressure buffering member 24 has a thickness of 100 μm.
It is produced by bonding a non-woven cloth (thickness: 500 μm) 63 lined with a μm polyethylene film 65. That is, the back surface of the nonwoven fabric 63 having a thickness of 500 μm has a thickness of 10
A 0 μm polyethylene film 65 is adhered with an adhesive 64, and the surface side of the nonwoven fabric 63 is adhered to the microcapsule dispersion layer 20 with an adhesive 62. The surface of the microcapsule dispersion layer 20 is formed with irregularities due to the microcapsules.
a is also filled with the adhesive 62. More specifically, FIG. 8 shows a cross-sectional view of the pressure buffer member, and the pressure buffer member 24 has a thickness of 500 μm as shown in FIG.
A synthetic resin film 65 made of polyethylene having a thickness of 100 μm is adhered to the back surface of the non-woven cloth 63 having a thickness of 80 μm.
m) bonded by 64. Further, the surface thereof is covered with an adhesive 62 and covered with a release paper 66. When bonding the pressure buffer member 24 to the uneven surface of the microcapsule dispersion layer 20 shown in FIG. 7, the release paper 66 is peeled off before bonding. The adhesive 62 penetrates into the concave portion (62a) of the uneven surface of the microcapsule dispersion layer 20 and adheres tightly to obtain an adhesive surface without voids (bubbles), and is firmly adhered. The thus obtained microcapsule magnetic display panel III was written in the same manner as in Example 1. As a result, clear characters could be obtained without crushing the microcapsule particles, and the microcapsule particles should be kept for a long time. Was completed. In addition, since the back surface was lined with the polyethylene film 65, it had sufficient durability against repeated use, and had little effect on magnetic force erasure.

[Example 8] Neuractish (Dainichi Seika Kogyo Co., Ltd.) was added as an aqueous coloring pigment to the aqueous adhesive 61 of the microcapsule dispersion layer of the microcapsule magnetic display panel III produced in Example 7. Example 7 except that
A microcapsule magnetic display panel was manufactured in the same manner as
By adding a pigment in this manner, the magnetic display plate can be colored, and similarly, can be colored in various colors.

Embodiment 9 FIG. 9 is a sectional view showing a microcapsule magnetic display panel according to another embodiment of the present invention. In FIG. 9, instead of the sheet 60 of the pressure buffer member 24 of the microcapsule magnetic display panel II (see FIG. 6) manufactured in Example 6, a 150 μm-thick polyethylene terephthalate 67 is adhered with an acrylic emulsion-based adhesive. Layer 6
2 was formed to produce a microcapsule magnetic display panel IV. At this time, the thickness of the adhesive layer 62 was 50 μm. The obtained microcapsule magnetic display panel IV was written in the same manner as in Example 1. As a result, clear characters were obtained without the microcapsule particles being crushed, and the microcapsule particles could be kept for a long time. Further, since the back surface was made of the polyethylene film 67, it had sufficient durability against repeated use, and had almost no effect on magnetic force erasure.

Embodiment 10 After silica was added as a filler to the adhesive forming the pressure buffer member of the microcapsule magnetic display panel IV manufactured in Embodiment 9, polyethylene terephthalate was bonded in the same manner as in Embodiment 9. An adhesive layer was formed by bonding with an agent to provide a pressure buffering member. At this time, the thickness of the adhesive layer was 50 μm. When the obtained microcapsule magnetic display panel IVa (not shown) was written in the same manner as in Example 5, the addition of silica not only increased the adhesive strength of the adhesive layer but also exhibited a sufficient pressure buffering effect. A clear character was obtained without crushing the microcapsule particles, and could be kept as it was for a long time. Also, since the back side is a polyethylene film,
It had sufficient durability for repeated use, and had little effect on magnetic force erasure.

Example 11 The thickness of the transparent film layer 21 described in Example 6 was 50 μm, 80 μm, respectively.
Microcapsule magnetic display panels IIa, IIb, IIc, and IId (not shown) were produced in the same manner as in Example 6, except that thicknesses of 100 μm and 180 μm were used. Each of the obtained microcapsule magnetic display panels II having a transparent film layer having a thickness of 50 μm is particularly preferable when used in connection with a computer such as an automatic electromagnetic system. When the thickness is 180 μm, it is particularly preferable when used for relatively young children, such as infants, because it is strong.

Example 12 The thickness of the nonwoven fabric described in Example 6 was 50 μm, 120 μm, and 150 μm, respectively.
m, 180 μm, 200 μm, 250 μm, 300 μ
m, 340 μm, and 420 μm in thickness, respectively, except that microcapsule magnetic display plates IIe, IIf, IIg, IIh, IIi,
IIj, IIk, IIm, IIn (not shown)
Was prepared. Each Microcapsule Magnetic Display Panel I Obtained
I is particularly preferable when the nonwoven fabric has a thickness of 50 μm and is used in connection with a computer such as an automatic electromagnetic system, and when the nonwoven fabric has a thickness of 400 μm, it is relatively low for infants and the like. Particularly preferred when serving as a child of age.

Example 13 The synthetic resin films made of polyethylene terephthalate described in Example 9 had thicknesses of 50 μm, 80 μm, 100 μm and 125 μm, respectively.
Microcapsule magnetic display plates IVb, IVc, IVd, IVe, IVf, IVg in the same manner as in Example 9 except that the thicknesses of μm, 180 μm, and 200 μm were used.
(Not shown). The obtained microcapsule magnetic display panel IV has a synthetic resin film thickness of 5
The one with a thickness of 0 μm is particularly preferable when used in connection with a computer such as an automatic electromagnetic system, and the one with a thickness of 200 μm is used for relatively young children such as infants. Sometimes particularly preferred.

Example 14 The synthetic resin film described in Example 9 having a thickness of 150 μm was used.
Microcapsule magnetic display panels IVh and IVi (not shown) were produced in the same manner as in Example 9 except that the thickness of the adhesive layer was 30 μm or 80 μm, respectively. The obtained microcapsule magnetic display panel IV is particularly preferable when the thickness of the adhesive layer is 30 μm IVh when used in connection with a computer such as an automatic electromagnetic system. Is 80 μm,
It is particularly preferable when used for relatively young children such as infants.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a microcapsule for magnetic display of the present invention.

FIG. 2 is a flow sheet for producing a dispersion of microcapsules of the present invention.

FIG. 3 is a sectional view showing a coating apparatus for manufacturing the microcapsule magnetic display panel of the present invention. (A) is a coating step, (b) is a drying step, and (c)
Is a laminating step.

FIG. 4 is a sectional view showing a microcapsule magnetic display panel obtained by the present invention.

FIG. 5 is a cross-sectional view showing a method of displaying characters on the microcapsule magnetic display panel obtained by the present invention, and a is a cross-sectional view showing a state where a magnet is scanned on the back surface of the magnetic display panel. is there. FIG. 2B is a cross-sectional view illustrating a state where characters are displayed on the surface of the magnetic display panel using a magnet.

FIG. 6 is a sectional view showing another embodiment of the microcapsule magnetic display panel of the present invention.

FIG. 7 is a sectional view showing another embodiment of the microcapsule magnetic display panel of the present invention.

FIG. 8 is a sectional view showing a pressure buffer member of the microcapsule magnetic display panel of the present invention.

FIG. 9 is a sectional view showing still another embodiment of the microcapsule magnetic display panel of the present invention.

[Explanation of symbols]

1, 31, 32, 33, 34, 35 Microcapsules 2 Capsule coating 10 Container 3 Magnetic powder 71 Aqueous slurry solution 4 Nonmagnetic powder 72 Binder 5 Dispersion medium 14, 15,
16 Roller 6,19 tank 17 Ben belt conveyor 61 aqueous adhesive (binder) 18 coated ink-like material 62, 64 adhesive 20 coating layer 62a recesses 21 transparent sheet 63 nonwoven 22 Rack 65 Polyethylene full I le arm 23 cover sheet 66 Release paper 24 Pressure buffer member 67 Polyethylene terephthalate 25 Drying chamber 7, 11 Stirrer 28 Suction member 8 Filtration device 81 Eraser 81, 82 Filter 82 Writing implement 9 Faucet 83, 84 hole 85, 86, 87 Particles

Claims (18)

(57) [Claims] 1. A microcapsule for magnetic display, wherein a dispersion medium, a magnetic powder and a non-magnetic powder in which a low-boiling solvent and a high-boiling solvent are combined is encapsulated. The boiling point solvent has compatibility, and the low boiling point solvent has a boiling point of 100 ° C. to 150 ° C. and a viscosity of 0.8 cp.
(25 ° C.) or lower, and the high boiling point solvent has a boiling point of 240 ° C.
350 ° C., the viscosity is 3 to 12 cps (25 ° C.), and the particle diameters of the magnetic powder and the non-magnetic powder are substantially the same,
Further, the microcapsules for magnetic display have a particle diameter of 800 μm or less and an average particle diameter of 200 μm to 600 μm. 2. The microcapsule for magnetic display according to claim 1, wherein a dispersant is contained in the dispersion medium. 3. The microcapsule for magnetic display according to claim 1, wherein the dispersion medium contains a suspending agent. 4. The microcapsule having a particle size of 200 μm ± x
4. The microcapsule for magnetic display according to claim 1, wherein the microcapsule is substantially formed of particles in a range of μm to 600 μm ± x μm (where x = 10 to 50). 5. A microcapsule magnetic display comprising, in order, an adhesive layer, a dispersion layer containing the microcapsules according to claim 1 and a transparent film surface sheet on a pressure buffer member. Board. 6. The microcapsule magnetic display panel according to claim 5, wherein the pressure buffer member is a non-woven cloth. 7. The microcapsule magnetic display panel according to claim 6, wherein the thickness of the nonwoven fabric is from 250 μm to 500 μm. 8. The microcapsule magnetic display panel according to claim 5, wherein the pressure buffer member is a synthetic resin film. 9. The synthetic resin film is a polyester film, a polyethylene film, a polypropylene film,
The microcapsule magnetic display panel according to claim 8, which is one of a polyvinyl chloride film and a polycarbonate film . 10. The synthetic resin film has a thickness of 50 μm to 2 μm.
10. The structure according to claim 8, wherein the thickness is 00 μm.
7. The microcapsule magnetic display panel according to 1. 11. The adhesive layer has a thickness of 30 μm to 300 μm.
The microcapsule magnetic display panel according to claim 5, wherein: 12. The method according to claim 5, wherein the binder of the dispersion layer containing the microcapsules is a transparent aqueous adhesive.
A microcapsule magnetic display panel according to claim 11. 13. The transparent film surface sheet is any one of a polyethylene film, a polypropylene film, a polyvinyl chloride film, a polyester film, and a polycarbonate.
3. The microcapsule magnetic display panel according to any one of 2. 14. A transparent film surface sheet having a thickness of 30 μm.
The microcapsule magnetic display panel according to any one of claims 5 to 13 , wherein the thickness is from m to 250 m . 15. A colorant is contained in at least one of a dispersion medium, a microcapsule coating, a transparent film layer, a transparent aqueous adhesive or a pressure buffer member in the microcapsule dispersion layer in the microcapsules. A microcapsule magnetic display panel according to any one of claims 5 to 14. 16. The method for manufacturing a microcapsule magnetic display panel according to claim 5, wherein the steps (1) to (8) are performed. (1) Step of adding magnetic powder, non-magnetic powder and dispersion medium to an aqueous solution of gelatin at 20 ° C. to 60 ° C. and stirring the mixture. (2) After adding an aqueous solution of gum arabic to the obtained mixed solution, lower the pH and acidify And further reducing the temperature to 20 ° C. or lower to form a gelatin / gum arabic polymer film (3) curing the polymer film to form microcapsules (4) averaging the obtained microcapsules (5) a step of dispersing the obtained microcapsules in an aqueous transparent adhesive to produce a microcapsule dispersion (6) ) Step of applying the dispersion to a transparent substrate (7) Step of drying the obtained transparent substrate to form a microcapsule dispersion coating layer (8) Applying a pressure buffer member to the surface of the obtained dispersion coating layer Setting Process 17. The method according to claim 16, wherein in step (4), the aqueous solution is concentrated to 40% to 70% in order to remove water. 18. The method according to claim 16, wherein in the step (5), the aqueous transparent adhesive is one of an aqueous urethane resin, an aqueous aromatic polyester resin and an aqueous dispersion type urethane resin. A method for producing the microcapsule magnetic display panel according to the above.