JP7246787B1 - Magnetic sheet, whiteboard, and method for manufacturing magnetic sheet - Google Patents

Abstract

A magnetic sheet that can be easily handled is provided. A magnetic sheet (1) includes a first base film (11) made of a synthetic resin, a magnetic layer (12) formed on one surface (11a) of the first base film (11) and containing at least magnetic powder and a binder resin, A removable adhesive layer 13 formed on the surface 12a of the magnetic layer 12 opposite to the first base film 11, and a release film laminated on the surface 13a of the adhesive layer 13 opposite to the magnetic layer 12. 14, and the binder resin has a glass transition point of −5° C. or lower. [Selection drawing] Fig. 1

Description

The present invention relates to a magnetic sheet, a whiteboard, and a method for manufacturing a magnetic sheet.

Conventionally, as disclosed in Patent Document 1, a magnetic sheet is known in which a magnetic layer containing magnetic powder and a binder resin is laminated on a base film made of a synthetic resin.

In the magnetic layer of such a magnetic sheet, magnetic powder is dispersed in the binder resin. There have been times when

JP-A-2004-31578

As described above, if the magnetic layer is highly brittle or if the adhesion between the magnetic layer and the base film is low, the magnetic layer may collapse or separate from the base film when the magnetic sheet is bent. The handling of the magnetic sheet during use, transportation, storage, etc. is complicated.

Accordingly, the present invention provides a magnetic sheet, a whiteboard, and a method for manufacturing a magnetic sheet that can be easily handled.

The magnetic sheet, the whiteboard, and the magnetic sheet manufacturing method that solve the above problems have the following features.

That is, the magnetic sheet includes a first base film made of a synthetic resin, and a magnetic layer formed on one surface of the first base film and containing at least magnetic powder and a binder resin, wherein the binder resin is , the glass transition point is −5° C. or lower.

As a result, the magnetic sheet can be easily bent, and handling such as use, transportation, and storage of the magnetic sheet can be simplified.

Also, the binder resin is an acrylic acid ester copolymer.

This can prevent the magnetic layer from collapsing or peeling off from the first base film when the magnetic sheet is bent.

Further, a removable adhesive layer formed on the surface of the magnetic layer opposite to the first base film, and a release film laminated on the surface of the adhesive layer opposite to the magnetic layer. , provided.

Thus, by peeling the release film from the adhesive layer, the adhesive layer can be brought into contact with the surface to be adhered, and the magnetic sheet can be attached. In addition, the magnetic sheet peeled off from the surface to be adhered can be reattached to the surface to be adhered for use.

Further, a first release agent layer is formed on the surface of the first base film opposite to the magnetic layer.

Thereby, the magnetic sheet can be used as a whiteboard, and the whiteboard can be easily installed at any place.

Also, the first release agent layer contains a polyethylene derivative as a release agent.

This facilitates adjustment when applying the first release agent layer, and can improve productivity.

Further, a removable adhesive layer formed on the surface of the magnetic layer opposite to the first base film, and a release film laminated on the surface of the adhesive layer opposite to the magnetic layer. and a second base film formed of a synthetic resin, and a second base film formed on the surface of the second base film on the side of the first base film, the second base film being formed in addition to the first base film An adhesion layer for adhesion to a surface, and a second release agent layer formed on the surface of the second base film opposite to the adhesion layer.

As a result, the magnetic sheet can be used as a whiteboard, and the whiteboard can be installed at any location. Also, the durability of the magnetic sheet can be improved.

Also, the second release agent layer contains a polyethylene derivative as a release agent.

This facilitates adjustment when applying the second release agent layer, and can improve productivity.

A whiteboard comprises the magnetic sheet according to claim 4, and uses the first release agent layer as a writing layer.

This allows the whiteboard to be easily installed at any desired location.

A whiteboard comprises the magnetic sheet according to claim 6, and uses the second release agent layer as a writing layer.

This allows the whiteboard to be easily installed at any desired location.

The magnetic sheet manufacturing method according to claim 1 or 2, further comprising a slurry generating step of mixing the magnetic powder, the binder resin, and a solvent to generate a slurry; and a drying step of drying the slurry applied to the first base film to form the magnetic layer. A succinic acid type surfactant is added as a dispersing aid.

Thereby, the magnetic powder can be stably dispersed in the slurry.

The slurry contains the magnetic powder, the solvent, the binder resin, and the dispersing aid in a weight ratio of magnetic powder:solvent:binder resin:dispersing aid=25:10:3:1. there is

As a result, the magnetic powder can be stably dispersed in the slurry.

The magnetic sheet manufacturing method according to claim 1 or 2, further comprising a slurry generating step of mixing the magnetic powder, the binder resin, and a solvent to generate a slurry; and a drying step of drying the slurry applied to the first base film to form the magnetic layer. is added.

This facilitates uniform dispersion of the magnetic powder in the slurry.

The slurry contains the magnetic powder, the solvent, the binder resin, and the diatomaceous earth in a weight ratio of magnetic powder:solvent:binder resin:diatomaceous earth=25:10:3:2.

This makes it particularly easy to uniformly disperse the magnetic powder in the slurry.

According to the present invention, handling such as use, transportation and storage of the magnetic sheet can be simplified.

It is a side sectional view showing a magnetic sheet. It is a perspective view which shows a magnetic sheet. It is side sectional drawing which shows the magnetic sheet which concerns on another embodiment. FIG. 4 is a diagram showing a flow when forming a magnetic layer;

Next, a mode for carrying out the present invention will be described with reference to the accompanying drawings.

The magnetic sheet 1 shown in FIGS. 1 and 2 is an embodiment of the magnetic sheet according to the present invention, and includes a first base film 11, a magnetic layer 12, an adhesive layer 13, a release film 14, and a first and a release agent layer 15 .

The first base film 11 is made of synthetic resin. Although the thickness of the first base film 11 is not particularly limited, it is preferably 10 μm to 200 μm, more preferably 50 μm to 100 μm. As the synthetic resin forming the first base film 11, for example, PET (Polyethylene terephthalate), nylon, polyimide, PE (Polyethylene), OPP (Oriented Polypropylene), and other olefin resins can be used.

The magnetic layer 12 is formed on one surface 11 a of the first base film 11 . The magnetic layer 12 contains at least magnetic powder and binder resin. Although the thickness of the magnetic layer 12 is not particularly limited, it can be formed to a thickness of 400 μm, for example. The coating thickness of the magnetic layer 12 can be 10 g to 200 g (dry)/m2.

For example, iron powder can be used as the magnetic powder. For the iron powder constituting the magnetic powder, for example, one having a particle size of 3 μm to 100 μm, an average particle size of 62 μm, and an apparent specific gravity of 2.52 g/m3 can be used. More preferably, the particle size of the iron powder is 3 μm to 30 μm. Further, the iron powder preferably has an apparent specific gravity of 1.8 to 2.6 g/m3. As the magnetic powder, it is possible to use nickel, cobalt, ferrite, and the like.

A synthetic resin having a glass transition point (Tg) of −5° C. or lower can be used as the binder resin. By using a resin having a low glass transition point (Tg) of −5° C. or less as the binder resin in this way, the binder resin becomes flexible when the magnetic sheet 1 is used at room temperature, for example. Since the sheet 1 can be easily bent, handling such as use, transportation, and storage is simplified. In addition, even if the magnetic sheet 1 is bent, it is possible to prevent the magnetic layer 12 containing the binder resin from collapsing or peeling off from the first base film 11 . The glass transition point (Tg) of the binder resin contained in the magnetic layer 12 is more preferably −15° C. or lower.

Examples of binder resins that can be used include acrylic acid ester copolymers such as alkyl acrylic acid ester copolymers, vinyl chloride, and polyethyleneimine. In this case, acrylic ester copolymers, which are copolymers of acrylic esters and derivatives thereof, are particularly excellent in flexibility and adhesiveness. The magnetic sheet 1 can be easily bent, and the magnetic layer 12 can be prevented from peeling off from the first base film 11 .

As the acrylic acid ester copolymer, for example, an acrylic acid ester copolymer composed of butyl acrylate and 2-ethylhexyl acrylate can be used. Also, the "acrylic acid" in the "acrylic acid ester copolymer" may be "methacrylic acid". Furthermore, when an acrylic acid ester copolymer is used as the binder resin, a small amount of acrylic acid amide, such as 1 part to 5 parts, and methacrylic acid can be used as a glass transition point (Tg) adjuster. .

The adhesive layer 13 is formed on the surface 12 a of the magnetic layer 12 opposite to the first base film 11 . Although the thickness of the adhesive layer 13 is not particularly limited, it can be formed to have a thickness of 20 μm, for example.

The magnetic sheet 1 can be attached to a surface to be adhered such as a wall surface indoors by bringing the adhesive layer 13 into contact with the surface to be adhered. The adhesive layer 13 is a re-peelable adhesive layer that can be peeled off from the adherend surface without leaving the adhesive layer 13 on the adherend surface after being attached to the adherend surface.

The adhesive layer 13 is composed of, for example, an adhesive containing particles, 50% by weight or more of the particles have a diameter of 80 to 120% of the thickness of the adhesive, and the content of the particles is 100% of the adhesive. It is 5 parts by weight to 30 parts by weight.

The adhesive constituting the adhesive layer 13 is not particularly limited, but for example, polyacrylic acid ester-based resin, polyurethane-based, natural rubber-based, synthetic rubber-based, and polysilicon-based adhesives can be used.

The material of the particles constituting the adhesive layer 13 is not particularly limited, but plastic or inorganic particles can be used. Examples of plastics to be used include polymethacrylate, polyethylene methacrylate, polystyrene, polystyrene acrylic, polyethylene, polypropylene, polystyrene butadiene, polystyrene divinylbenzene, polyurethane, polybenzoguanamine, and melamine. can be done. Inorganic materials that can be used include glass, silica (silicate mineral), calcium carbonate, and the like.

However, the adhesive layer 13 is not limited to this configuration as long as it can be peeled off again after being attached to the surface to be adhered.

The release film 14 is laminated on the surface 13 a of the adhesive layer 13 opposite to the magnetic layer 12 . Although the thickness of the release film 14 is not particularly limited, it can be formed to have a thickness of 50 μm, for example.

The release film 14 is not particularly limited as long as it is a material that can be released from the laminated adhesive layer 13. For example, a release layer such as silicone resin, fluorine resin, and alkyd resin may be used as a PET (Polyethylene). terephthalate), paper, a film formed on a substrate such as polypropylene, or a film formed from a single substrate having peelability such as polypropylene. The release film 14 laminated on the adhesive layer 13 can expose the adhesive layer 13 by peeling it off when the magnetic sheet 1 is attached to the surface to be adhered.

The first release agent layer 15 is formed on the other surface 11b of the first base film 11 opposite to the one surface 11a. Although the thickness of the first release agent layer 15 is not particularly limited, it can be formed to have a thickness of, for example, 0.1 μm to 0.2 μm.

The first release agent layer 15 is written on the other surface 11b of the first base film 11 on which the first release agent layer 15 is formed, with a whiteboard marker and a water-based marker, and with a whiteboard marker and a water-based marker. erasure.

As the release agent forming the first release agent layer 15, for example, a polyethylene derivative can be used. Specifically, the first release agent layer 15 is formed of a release agent mainly composed of, for example, a reaction product of an ethylene/vinyl alcohol copolymer and an alkyl isocyanate having at least 8 carbon atoms. be able to. In this case, as the ethylene/vinyl alcohol copolymer, for example, an ethylene/vinyl alcohol copolymer having an ethylene copolymerization ratio of 0.1 to 0.9 represented by the following formula 1 can be used.

Since the polyethylene-based derivative, which is the release agent that forms the first release agent layer 15, can be diluted with a solvent such as toluene, adjustment during coating is easy, and productivity can be improved. can be planned.

As the release agent forming the first release agent layer 15, it is possible to use an oil/silicone release agent and a fluorine release agent. Since the oil/silicone release agent is liquid, it can be applied over a wide area and is inexpensive.

However, silicone-based release agents require high-temperature baking at around 150° C., and if the baking temperature is insufficient, they may migrate to the other side. Therefore, if the first base film 11 does not have the heat resistance required when a silicone-based release agent is used as the first release agent layer 15, a material that can be processed at a low temperature is used as the first release agent layer 15. It is preferably used as the release agent layer 15 . For example, a long-chain alkyl pendant polymer can be used as a material that can be processed at a lower temperature than the silicone release agent. Long chain alkyl pendant polymers can be processed at 40°C to 80°C.

By peeling off the release film 14 from the adhesive layer 13 , the magnetic sheet 1 configured in this manner can be attached to, for example, a wall surface of an indoor wall with the adhesive layer 13 in contact with the surface of wallpaper. In other words, wall paper or the like can be used as the adhered surface of the magnetic sheet 1 .

By using the first release agent layer 15 as a writing layer, the magnetic sheet 1 attached to a wall surface or the like is a white board that allows writing with a whiteboard marker or water-based marker and erasable writing with a whiteboard marker or water-based marker. Can be used as a board. In addition, since the magnetic sheet 1 can be attached not only to the wall surface but also to any location where the adhesive layer 13 can be attached, the whiteboard can be easily installed in any location. be able to.

In this case, since the adhesive layer 13 attached to the wallpaper is configured to be removable, the magnetic sheet 1 can be removed from the wall surface without damaging the wallpaper after use. Furthermore, the magnetic sheet 1 that has been peeled off from the wall surface can be used again by attaching it to a surface to be adhered such as a wall surface. Further, since the magnetic sheet 1 has the magnetic layer 12, it is possible to attract a magnet to the magnetic sheet 1 when it is used by being attached to a surface to be adhered such as a wall surface.

The magnetic layer 12 of the magnetic sheet 1 uses a flexible synthetic resin having a glass transition point (Tg) of −5° C. or less as a binder resin, so that the magnetic sheet 1 can be easily bent. It is possible to simplify handling such as use, transportation, and storage of.

In addition, in the magnetic sheet 1, an acrylic acid ester copolymer, which is particularly excellent in flexibility and adhesiveness, is used as the binder resin. detachment from the first base film 11 can be suppressed.

[Another embodiment of the magnetic sheet]
Magnetic sheet 1A shown in FIG. and an agent layer 18 . In other words, the magnetic sheet 1A does not include the first release agent layer 15 and includes the second base film 16, the adhesive layer 17, and the second release agent layer 18, It is different from the magnetic sheet 1.

The second base film 16 is made of synthetic resin. Although the thickness of the second base film 16 is not particularly limited, it can be formed to a thickness of 20 μm to 50 μm. As the synthetic resin forming the second base film 16, for example, PET (Polyethylene terephthalate), nylon, polyimide, PE (Polyethylene), OPP (Oriented Polypropylene), and other olefin resins can be used.

The adhesive layer 17 is formed on the surface 16a of the second base film 16 on the first base film 11 side. Although the thickness of the adhesive layer 17 is not particularly limited, it can be formed to have a thickness of 20 μm, for example. The second base film 16 is adhered to the other surface 11 b of the first base film 11 with an adhesive layer 17 . That is, the sticking layer 17 sticks the second base film 16 to the other surface 11 b of the first base film 11 .

The sticking layer 17 can be made of the same adhesive as the adhesive layer 13 . That is, the adhesive layer 17 is, for example, an adhesive containing particles, 50% by weight or more of the particles have a diameter of 80 to 120% of the thickness of the adhesive, and the content of the particles is 100% of the adhesive. It can be composed of a pressure-sensitive adhesive in an amount of 5 to 30 parts by weight. The adhesive and particles in this case can also be the same as in the case of the adhesive layer 13 .

The adhesive layer 17 can also be made of an adhesive that does not contain particles. In this case, the adhesive constituting the adhesive layer 13 is not particularly limited, but for example, polyacrylic acid ester-based resin, polyurethane-based, natural rubber-based, synthetic rubber-based, and polysilicon-based adhesives can be used. is.

However, the sticking layer 17 is not limited to this configuration as long as it can stick the second base film 16 to the first base film 11 .

The second release agent layer 18 is formed on the surface 16 b of the second base film 16 opposite to the adhesive layer 17 . The surface 16b of the second base film 16 is the surface opposite to the surface 16a on the first base film 11 side. Although the thickness of the second release agent layer 18 is not particularly limited, it can be formed to have a thickness of, for example, 0.1 μm to 0.2 μm.

The second release agent layer 18 can be written on the surface 16b of the second base film 16 on which the second release agent layer 18 is formed, using a whiteboard marker and water-based marker, and writing with a whiteboard marker and water-based marker. Allow erasure.

The second release agent layer 18 can be formed from the same release agent as the first release agent layer 15 . That is, as the second release agent layer 18, for example, a release agent composed of a polyethylene derivative can be used. Specifically, the second release agent layer 18 is formed of a release agent mainly composed of, for example, a reaction product of an ethylene/vinyl alcohol copolymer and an alkyl isocyanate having at least 8 carbon atoms. be able to. In this case, as the ethylene/vinyl alcohol copolymer, for example, an ethylene/vinyl alcohol copolymer having an ethylene copolymerization ratio of 0.1 to 0.9, as shown in Formula 1, can be used. Since the polyethylene-based derivative, which is the release agent that forms the second release agent layer 18, can be diluted with a solvent such as toluene, adjustment at the time of coating is easy, and productivity can be improved. can be planned.

In the magnetic sheet 1A configured in this manner, the release film 14 is peeled off from the adhesive layer 13 in the same manner as the magnetic sheet 1, so that the adhesive layer 13 is brought into contact with, for example, the surface of wallpaper on an indoor wall surface. can be pasted.

As with the magnetic sheet 1, the magnetic sheet 1A attached to the surface to be adhered such as a wall surface can be used for writing with a whiteboard marker or water-based marker, as well as white paper, by using the second release agent layer 18 as a writing layer. It can be used as an erasable whiteboard with board markers and water-based markers. This makes it possible to easily install the whiteboard at any desired location.

In the magnetic sheet 1A, the second base film 16 having the second release agent layer 18 is adhered to the first base film 11 having the magnetic layer 12 by the adhesive layer 17. , the strength of the magnetic sheet 1A is improved as a whole, and it is possible to improve the durability of the magnetic sheet 1A.

[Method for Forming Magnetic Layer in Magnetic Sheet]
A method of forming the magnetic layer 12 when manufacturing the magnetic sheet 1 will be described. As shown in FIG. 4, when forming the magnetic layer 12 on the one surface 11a of the first base film 11, a slurry generating step S01, a coating step S02, and a drying step S03 are performed.

In the slurry generating step S01, the magnetic powder and binder resin constituting the magnetic layer 12 are mixed with a solvent and stirred by a disperser to disperse the magnetic powder in the solvent to generate slurry. In this case, for example, toluene, xylene, methyl ethyl ketone, ethyl acetate, cyclohexane, normal hexane, and lower alcohols can be used as solvents.

When the magnetic powder is dispersed in a solvent, it is difficult to stably disperse the magnetic powder in the slurry simply by mixing the magnetic powder, the binder resin, and the solvent because the magnetic powder such as iron has a large specific gravity. be.

Therefore, in the slurry generation step S01, the magnetic powder is stably dispersed in the slurry by adding a dispersing aid to the slurry. As the dispersing aid, for example, a sulfosuccinic acid-type surfactant such as alkylsulfosuccinic acid can be used. As the sulfosuccinic acid-type surfactant, for example, sodium di-2-ethylhexylsuccinate represented by Formula 2 below can be used.

Examples of dispersion aids for stably dispersing the magnetic powder in the slurry include polycarboxylic acids, naphthalenesulfonate formalin condensates, polyoxyethylene-type nonionic surfactants, alkyltrimethylammonium liquids, Dialkyl(14-18)dimethylammonium, distearyldimethylammonium chloride, stearyltrimethylammonium, distearyldimonium chloride, and stearamidopropyldimethylamine, and various amine compounds such as pyridine, diethylenetriamine, triethanolamine, and polyethyleneimine. can also be used.

Further, since the magnetic powder such as iron has a large specific gravity, it settles in the slurry in a short period of time and tends to form a hard cake in the lower layer of the slurry. Therefore, in the slurry production step S01, by adding diatomaceous earth with a small specific gravity to the slurry, sedimentation of the magnetic powder in the slurry can be suppressed and the magnetic powder can be stably dispersed in the slurry. As diatomaceous earth added to the slurry, diatomaceous earth having a particle size of, for example, 5 μm to 30 μm can be used.

In this case, in the slurry, the magnetic powder and the diatomaceous earth are bound via the binder resin, so that the sedimentation of the magnetic powder can be suppressed, and the magnetic powder can be easily dispersed uniformly in the slurry. This makes it possible to suppress the formation of hard cakes in the slurry.

In the present embodiment, the slurry generated in the slurry generating step S01 is composed of magnetic powder, solvent, binder resin, dispersion aid, and diatomaceous earth, and magnetic powder:solvent:binder resin:dispersion aid:diatomaceous earth=25: It contains a weight ratio of 10:3:1:2. By including the dispersion aid in such a ratio, the slurry can stably disperse the magnetic powder in the slurry. In addition, by including diatomaceous earth in such a ratio, it becomes easier to evenly disperse the magnetic powder in the slurry. In this embodiment, the slurry contains both the dispersing aid and diatomaceous earth, but it is also possible to add either one of the dispersing aid and diatomaceous earth to the slurry.

In addition, by adding a small amount of butyral-based resin when the slurry is produced in the slurry production step S01, it is possible to lengthen the time until the dispersed magnetic powder settles. In this way, by lengthening the time until the magnetic powder settles, the dispersion stability of the magnetic powder can be improved when forming the magnetic layer 12 .

After the slurry generation step S01, the application step S02 is performed. In the application step S02, the slurry produced in the slurry production step S01 is applied to one surface 11a of the first base film 11. As shown in FIG. In this case, the slurry is applied so as to form a coating film having a uniform thickness on the one surface 11a of the first base film 11 . The slurry can be applied to one surface 11a of the first base film 11 using a coating device such as a die coater, a comma coater, a gravure coater, and a bar coater.

A drying step S03 is performed after the coating step S02. In the drying step S03, the slurry applied to one surface 11a of the first base film 11 is dried to form a magnetic layer. Drying of the slurry can be performed, for example, by heating the first base film 11 coated with the slurry. In this case, the heating temperature of the first base film 11 coated with the slurry can be set to, for example, about 120° C. or less.

The first base film 11 coated with the slurry can be heated by a heating furnace, hot air blowing, or the like. Since the first base film 11 is heated in the drying step S03, it is required to have heat resistance stability at least at the heating temperature in the drying step S03.

When manufacturing the magnetic sheet 1, it takes about 6 to 12 hours from generating the slurry to applying the slurry to the first base film 11 and drying it. Therefore, when a dispersion aid and diatomaceous earth are added to the slurry to stably disperse the magnetic powder in the slurry, the magnetic powder is stabilized for at least the time required from slurry generation to coating and drying. It suffices if a reasonable dispersion can be maintained.

Further, when a dispersion aid and diatomaceous earth are added to the slurry in the slurry production step S01, the magnetic layer formed by drying the slurry contains the dispersion aid and diatomaceous earth.

Although the method of forming the magnetic layer 12 in the magnetic sheet 1 has been described in this embodiment, the method of forming the magnetic layer 12 in the magnetic sheet 1A is the same.

REFERENCE SIGNS LIST 1, 1A magnetic sheet 11 first substrate film 11a one surface 11b other surface 12 magnetic layer 12a surface (of the magnetic layer opposite to the first substrate film) 13 adhesive layer 13a (side of the adhesive layer opposite to the magnetic layer 14 release film 15 first release agent layer 16 second base film 16a (on the first base film side of the second base film) face 16b (opposite to the adhesion layer of the second base film side) surface 17 adhesive layer 18 second release agent layer S01 slurry generation step S02 coating step S03 drying step

Claims (13)

a first base film made of a synthetic resin;
A magnetic layer formed on one surface of the first base film and containing at least magnetic powder and a binder resin,
The magnetic powder is iron powder,
The binder resin is an acrylic acid ester copolymer having a glass transition point of −5° C. or lower ,
A magnetic sheet comprising the magnetic powder and the binder resin in a weight ratio of magnetic powder:binder resin=25:3 . 2. The magnetic sheet according to claim 1, wherein the magnetic layer has a coating thickness of 10 g to 200 g (dry)/m2. a removable adhesive layer formed on the surface of the magnetic layer opposite to the first base film;
a release film laminated on the surface of the adhesive layer opposite to the magnetic layer;
The magnetic sheet according to claim 1 or 2, comprising: 4. The magnetic sheet according to claim 3, further comprising a first release agent layer formed on the surface of the first base film opposite to the magnetic layer. 5. The magnetic sheet according to claim 4, wherein the first release agent layer contains a polyethylene derivative as a release agent. a removable adhesive layer formed on the surface of the magnetic layer opposite to the first substrate film;
a release film laminated on the surface of the adhesive layer opposite to the magnetic layer;
a second base film made of a synthetic resin;
an adhesive layer formed on the surface of the second base film on the side of the first base film for attaching the second base film to the other surface of the first base film;
a second release agent layer formed on the surface of the second base film opposite to the adhesive layer;
The magnetic sheet according to claim 1 or 2, comprising: 7. The magnetic sheet according to claim 6, wherein the second release agent layer contains a polyethylene derivative as a release agent. A whiteboard comprising the magnetic sheet according to claim 4, wherein the first release agent layer is used as a writing layer. A whiteboard comprising the magnetic sheet according to claim 6, wherein the second release agent layer is used as a writing layer. A method for manufacturing the magnetic sheet according to claim 1 or 2,
a slurry generating step of mixing the magnetic powder, the binder resin, and a solvent to generate slurry;
a coating step of coating the slurry on the one surface of the first base film;
a drying step of drying the slurry applied to the first base film to form the magnetic layer;
A method for producing a magnetic sheet, wherein in the slurry forming step, a sulfosuccinic acid-type surfactant is added to the slurry as a dispersing aid. The slurry contains the magnetic powder, the solvent, the binder resin, and the dispersion aid in a weight ratio of magnetic powder:solvent:binder resin:dispersion aid=25:10:3:1. Item 11. A method for producing a magnetic sheet according to Item 10. A method for manufacturing the magnetic sheet according to claim 1 or 2,
a slurry generating step of mixing the magnetic powder, the binder resin, and a solvent to generate slurry;
a coating step of coating the slurry on the one surface of the first base film;
a drying step of drying the slurry applied to the first base film to form the magnetic layer;
A method for manufacturing a magnetic sheet, wherein diatomaceous earth is added to the slurry in the slurry generating step. 13. The slurry according to claim 12, wherein the magnetic powder, the solvent, the binder resin, and the diatomaceous earth are contained in a weight ratio of magnetic powder:solvent:binder resin:diatomaceous earth=25:10:3:2. A method for manufacturing a magnetic sheet.

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