JP3271620B1 - Magnetic adsorption sheet - Google Patents

Abstract

An object of the present invention is to provide a magnetic attraction sheet for display which has improved adhesion at the time of sticking the sheet and powder dropping at the time of printing. SOLUTION: In a magnetic attraction sheet for display 1, a magnetic layer 5 mainly composed of a ferromagnetic powder and a polymer binder is formed on a nonmagnetic support 4. On the surface of the magnetic layer 5, a protective layer 6 mainly composed of a cellulose acetate resin is formed. The thickness of the protective layer 6 is in the range of 0.5 to 5 μm. The glass transition temperature Tg of the cellulose acetate resin is 110 ° C. or higher. The protective layer 6 includes particles having an average particle size of 5 to 20 μm,
5 to 100 parts by weight of cellulose acetate resin
Contains 20 parts by weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic attraction sheet for display having a cellulose acetate resin coated on the surface of a magnetic layer to prevent sticking.

[0002]

2. Description of the Related Art At present, magnetic attraction sheets utilizing magnetic attraction of permanent magnets are widely used as various display devices.
In particular, applications as office supplies are expanding.

In recent years, with the rapid spread of personal computers, the performance of peripheral devices such as printers has been remarkably improved, and the quality of printing by general-purpose printers has become comparable to that of commercial printing. At the same time, there is a growing desire to freely use those printed materials.

[0004] The first use of printed material is to display it. Fixing materials such as various adhesives, adhesive tapes, thumbtacks, and cap magnets are used to fix the display object at the presentation location. However, since the display object of the magnet sheet itself is a fixing material having a magnetic attraction property, when the presentation place is a ferromagnetic surface, it is possible to display alone without requiring another fixing material.

For this reason, magnet sheets are now being thinned so that they can be used in general-purpose printers and the like, and a magnetic paint containing ferromagnetic powder and a polymer binder as main components is coated on a non-magnetic support. By forming a magnetic layer by orientation, drying, and performing multipolar magnetization, it has become possible to provide a magnetically attractable sheet that is thin and can be printed by a general printer or the like.

[0006]

However, in the above-mentioned conventional magnetically attracting sheet, since the polymer binder is used as the main component of the magnetic layer, the surface of the magnetic layer is easily adhered, and the magnetic layer is adsorbed on the presenter for a long time. If the magnetic layer is adhered to the presenter such as a pot or a pot that is heated, the surface of the magnetic layer sticks to the presenter, and not only may the magnetic layer be destroyed, but also the presenter may be soiled. Further, since the surface of the magnetic layer is exposed, when a general printer or the like is used, there is a possibility that the pigment may fall off from the surface of the magnetic layer during printing.

[0007] The present invention has been made in view of the above problems, and by coating a cellulose acetate resin on the magnetic layer surface of a magnetically attracting sheet, the adhesion at the time of sticking the sheet and the printing at the time of printing. An object of the present invention is to provide a magnetic attraction sheet for display with improved powder dropping and the like.

[0008]

According to the present invention, there is provided a magnetic adsorption sheet comprising a non-magnetic support, a magnetic coating mainly composed of a ferromagnetic powder and a polymer binder applied to the non-magnetic support, and dried. A magnetic layer formed by the method, wherein the easy axis of magnetization of the ferromagnetic powder in the magnetic layer is oriented in the in-plane direction with respect to the magnetic layer, and the magnetic layer is multipolar magnetized in the in-plane direction. A protective layer formed on the surface of the magnetic layer for preventing adhesion and peeling of the magnetic layer, which is mainly composed of a cellulose acetate resin having a glass transition temperature Tg of 110 ° C. or higher and has a thickness of 0 0.5 to 5 μm.

[0009] Also, the protective layer described above has an average particle size 5 to 20
The particles of μm may be contained in an amount of 5 to 20 parts by weight based on 100 parts by weight of the cellulose acetate resin .

According to the magnetic attraction sheet for display of the present invention,
By forming a protective layer containing cellulose acetate resin as a main component on the surface of the magnetic layer, it is possible to prevent the surface of the magnetic layer from being sticky and prevent the surface of the magnetic layer from being exposed.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention relating to a magnetic attraction sheet for display will be described. In the present invention, a cellulose acetate-based resin is mainly coated on a magnetic layer surface of a magnetic adsorption sheet in which a conventional coating mainly composed of a ferromagnetic powder and a binder resin is applied to a nonmagnetic support and dried to form a magnetic layer. An object of the present invention is to provide a thin-film magnetic adsorption sheet which can be printed by a general home copying machine or a printer or the like by improving the adhesion and dusting of the sheet by coating the component.

The magnetic attraction sheet for display of the present invention has a recording layer on one side of a non-magnetic support which can be printed by a general home copying machine or a printer, and the other side. Has a magnetic layer containing a ferromagnetic powder and a polymer binder as main components, and the surface of the magnetic layer is coated with a cellulose acetate resin.

Hereinafter, specific embodiments of the present invention will be described for a magnetic attraction sheet for display. FIG. 1 shows an example of a magnetic attraction sheet 1 for display to which the present invention is applied. Examples of the non-magnetic recording medium 2 of the present invention include a white polyester film having a surface subjected to an easy adhesion treatment. For the purpose of applying the magnetic paint, it is preferable to use a coated paper, a synthetic paper, or a white synthetic film having a resin-coated back surface so that the solvent does not penetrate into the back side of the magnetic paint applied surface.

On one surface of the nonmagnetic support 4, a heat-sensitive layer, a thermal transfer ink-receiving layer, an ink-jet receiving layer, a printable ink-jet receiving layer, a dot impact-receiving layer, a laser It is possible to add a functional layer according to a printing method such as a printer toner receiving layer, and it is possible to appropriately select a receiving layer according to a display purpose and a printing method.

On the opposite side of the recording layer 3, there is provided a magnetic layer 5, and the ferromagnetic powder used to form the magnetic layer 5 is, for example, a Ba ferrite powder or a Sr ferrite powder. Ferromagnetic iron oxide and rare earth ferromagnetic materials such as Sm-Co powder, Sm-Fe-N powder, and Nd-Fe-B powder.

As a polymer binder for dispersing such a resin, a thermoplastic or thermosetting resin is used. The resin preferably used in the present invention is an epoxy resin, an ethylene-vinyl acetate copolymer, an ethylene-vinyl acetate block copolymer, a copolymer of ethylene and (meth) acrylate, or a block copolymer polyethylene or an acrylic resin. And organic polymer materials such as polyester resin and polyurethane resin. These may be used alone or in combination of several kinds of resins.

The proportion of the binder in the magnetic layer 5 is preferably 8 to 18 parts by weight based on 100 parts by weight of the ferromagnetic powder. If it is smaller than this, the magnetic attraction force can be increased, but the coating film becomes brittle, and the deformation of the sheet at the time of attachment / detachment tends to cause powder coating breakage such as powder dropping and cracking. If it is larger than this, the magnetic flux density is insufficient, and sufficient magnetic attraction performance cannot be obtained.

The protective layer 6 coated on the magnetic layer 5 has a cellulose acetate resin. Examples of the cellulose acetate resin include cellulose acetate butyrate and cellulose acetate propionate. Preferably, the cellulose acetate resin has a glass transition temperature Tg of 110 ° C. or higher. If the glass transition temperature is lower than 110 ° C., sticking between the magnetically attractable sheet for display 1 and the surface of the sign may occur.

Further, the protective layer 6 has an average particle size of 5 to 20.
The particles of μm may be added in an amount of 5 to 20 parts by weight based on 100 parts by weight of the cellulose acetate resin. But,
Adding particles having an average particle size larger than 20 μm,
If it is added in excess of parts by weight, it may be difficult to sufficiently disperse the particles.

The addition of these particles also prevents adhesion between the surface of the magnetic layer 5 of the magnetically attracting sheet 1 for display and the surface of the bulletin board, reduces inter-paper friction during printing, and causes double feeding during printing. Can be reduced. Examples of the particles include organic fillers (nylon filler, antistatic filler, rubber filler, and the like).

The protective layer 6 has a thickness of 0.5 to 0.5.
5 μm is desirable. If the thickness is less than 0.5 μm, it may be difficult to sufficiently protect the surface of the magnetic layer 5. Conversely, if the thickness is more than 5 μm,
May be too thick, and the magnetic properties of the magnetic layer 5 surface may be degraded.

The thickness of the magnetic layer 5 is desirably 0.03 mm or more and 0.15 mm or less. Since the magnetic energy of the permanent magnet is proportional to the volume of the magnet, the film thickness is 0.03 m
If it is less than m, the magnetic attraction force sufficient to stably fix the weight of the coating film plus the support to the vertical adsorption surface cannot be obtained. When the film thickness is larger than 0.15 mm, the magnetic attraction force is sufficient, but the coating film is likely to be broken due to mechanical fatigue due to repeated deformation of the sheet during attachment and detachment during long-term use.

Further, in order to obtain a stable magnetic attraction force of the sheet, the support immediately after coating is passed through a magnetic field in the direction of orientation, and the easy axis of the ferromagnetic powder in the coating is oriented. Good.

The total thickness of the magnetic attraction sheet according to the present invention is desirably 0.08 mm or more and 0.25 mm or less. The film thickness of the non-magnetic recording medium including the printing receiving layer provided on the display surface used in such a case is desirably 0.05 mm or more. If the thickness of the non-magnetic recording medium is less than 0.05 mm,
When used for printing purposes, the color of the magnetic layer penetrates the surface of the non-magnetic support, resulting in poor display appearance. Magnetic layer 5
When the maximum total thickness including the above exceeds 0.25 mm, it falls outside the range that can be handled by a general household printing press.

The magnetic layer 5 of the magnetic attraction sheet 1 for display according to the present invention has a non-magnetic support such as a gravure coater, a die coater, a knife coater, or the like, made of a coating obtained by sufficiently dispersing ferromagnetic particles in a polymer binder and a solvent. Made by applying on the body. The coated support has a magnetically adsorbed sheet in which the axis of easy magnetization of the ferromagnetic powder is oriented by passing through an orientation magnetic field, and furthermore, by passing through a hot air drier, the solvent in the paint evaporates and is dried and solidified. Is formed.

In the present invention, the protective layer 6 is formed on the formed magnetic layer 5 by coating a cellulose acetate resin or a coating material obtained by sufficiently dispersing particles having an average particle size of 5 to 20 μm in the resin with a disper or a ball mill. It is formed by applying a predetermined thickness using a coater, a die coater, a knife coater or the like.

In the magnetic attraction sheet for display 1 configured as described above, since the surface of the magnetic layer 5 is covered with the protective layer 6,
Even if the suction is performed for a long period of time and the surface to be heated is attracted such as a pot, the sticking between the magnetic attraction sheet 1 for display and the surface to be attracted can be prevented.
Even when printing is performed by various printers such as an IJ printer, a thermal transfer printer, a sublimation printer, and a laser printer, the powder of the pigment on the surface of the magnetic layer can be prevented from falling off.

By the way, the magnetic attraction sheet 1 for display to which the present invention is applied can be printed using various printing machines such as commonly used copying machines and IJ printers, thermal transfer printers, sublimation printers, laser printers and the like. .
For this reason, not only can you print and post images taken with a digital camera, etc., images taken with a scanner, etc., but also calendars and cooking recipes that are freely processed independently,
It prints schedules, posters (for elections, department stores, trains, etc.), wallpapers, car marks (beginner marks, etc.), photographs, etc., and various adhesives, adhesive tapes, thumbtacks on ferromagnetic surfaces such as refrigerators and streets Can be posted without using a fixing agent such as a cap magnet.

It should be noted that the present invention is not limited to the above-described embodiment, but can adopt various other configurations without departing from the gist of the present invention.

[0030]

EXAMPLE Next, as an example, a sample in which the magnetic attraction sheet for display 1 according to the present invention was actually manufactured will be described together with a sample manufactured as a comparative example. However, it goes without saying that the present invention is not limited to these examples.

Example 1 According to the following composition, a magnetic powder, a binder and a solvent were mixed by a ball mill and uniformly dispersed to prepare a magnetic paint. After adding 0.3 parts by weight of a curing agent (Coronate HL, manufactured by Nippon Polyurethane Co., Ltd.) to this coating material, a gravure coater is used to coat the back side of the printing surface of the base material: white synthetic paper with an ink jet-compatible receiving layer (0.08 mm thickness) It was coated and passed through an in-plane orientation magnetic field of 2 KG by opposing permanent magnets to perform in-plane orientation, and then dried to obtain a raw material having a magnetic layer of 0.05 mm and a total thickness of 0.13 mm. The obtained raw material was stored in a 60 ° C. environment for 20 hours or more and cured to obtain a conventional magnetic adsorption sheet A (see Table 1).

Magnetic powder Sr ferrite particles 100 parts by weight (isotropic particles average particle size = 1.2 μm, σs = 59 emu / g, Hc = 2800 Oe) Binder 12.5 parts by weight polyester polyurethane resin (OS029 Nippon Polyurethane Co., Ltd.) (Mw = 30000 Glass transition temperature Tg = 10 ° C.) Solvent Methyl ethyl ketone 66 parts by weight

Next, a cellulose acetate resin (CA
B: A) (see Table 2) and a solvent were mixed with the following composition,
Protective agent A was prepared. Resin CAB: A 100 parts by weight (cellulose acetate butyrate (hereinafter referred to as “CAB”)) (CAB-381-0.1 manufactured by Eastman Chemical Company) Solvent Methyl ethyl ketone 900 parts by weight

Conventionally, the protective agent A is applied to the magnetic surface of the magnetically attractable sheet A by gravure so that the thickness of the coating film after drying becomes 1 μm, dried and then multipolar magnetized (magnetization width 2.0 mm). As a result, a magnetic attraction sheet provided with a protective layer was produced.

[0035]

[Table 1]

[0036]

[Table 2]

Example 2 Next, using a protective agent A, a protective agent B was prepared by dispersing in a roll mill with the following composition.

Protecting agent A CAB 100 parts by weight Methyl ethyl ketone 900 parts by weight Nylon particles (average particle size: 10 μm) 5 parts by weight (EPOSTAR, manufactured by Nippon Shokubai Co., Ltd.)

Conventionally, a protective agent B is applied to the magnetic surface of the magnetically attracting sheet A by gravure so that the thickness of the coating film after drying becomes 1 μm, dried and then multi-polarized to provide a protective layer. An adsorption sheet was created.

[Examples 3 to 9] In Examples 3 to 9, the magnetic attraction sheet was manufactured in the same manner as in Example 1 except that the amount of added particles, the particle diameter, and the thickness of the coating film were changed as shown in Table 3. Was prepared.

Comparative Example 1 As a protective agent, a cellulose acetate resin was not used, and a polyurethane resin having a low glass transition temperature Tg (polyurethane resin MG) was used instead.
0130, manufactured by Toyobo Co., Ltd. (resin B in Table 2), and the thickness of the coating film was set to 1 μm to prepare a magnetic attraction sheet. Other conditions are the same as in the first embodiment. [Comparative Example 2] As a protective agent, a cellulose acetate resin was not used, and instead of this, an acetal resin having strong resin cohesion (acetal resin KS-10, manufactured by Sekisui Chemical Co., Ltd.)
Using (resin C in Table 2), the thickness of the coating film was set to 1 μm to prepare a magnetically attractable sheet. Other conditions are the same as in the first embodiment.

[Comparative Examples 3 to 8] In Comparative Examples 3 to 7, with respect to the protective agent CAB: A [100 parts by weight], the amount of added particles, the particle diameter, and the coating film thickness were changed to predetermined values. A magnetically attractable sheet of each sample was prepared. In Comparative Example 8, the conventional magnetic attraction sheet A was used without using a protective agent. Other conditions are the same as in the first embodiment.

The materials constituting the protective layer of the magnetically attracting sheets prepared in Examples 1 to 9 and Comparative Examples 1 to 8, ie, the resin, the amount of added particles, the particle size, and the thickness of the coating film are shown below. It is shown in Table 3 below.

[0044]

[Table 3]

The following characteristics were evaluated for Examples 1 to 9 and Comparative Examples 1 to 8 produced as described above.

<Blocking (Adhesion Resistance)> A sheet sample was cut into 8 cm × 8 cm, and a sheet adsorbed on a metal cabinet and a sheet adsorbed on the magnetic layers of the sheet were placed in a thermostat bath (45 ° C., relative pressure). (Humidity: 75%) for 7 days to confirm the presence or absence of adhesion. The evaluation was evaluated as satisfactory (○) when there was no adhesion, and as unsatisfactory (x) when there was adhesion.

<Dust resistance> After printing 100 sheets with an ink jet printer (Calario PM-3300C, manufactured by Seiko Epson Corporation), printing was performed on plain paper, and after printing, it was confirmed whether the plain paper was stained by magnetic powder. The evaluation was evaluated as satisfactory (o) when there was no dirt, and as unsatisfactory (x) when there was dirt.

<Adhesive Strength> A silicon tape was stuck on the surface of the magnetic layer. When the silicon tape was peeled off immediately after sticking and after 30 minutes had passed, it was confirmed whether the magnetic layer was peeled. Evaluation,
When it was not peeled, it was evaluated as satisfactory (O), and when it was peeled, it was evaluated as unsatisfactory (X).

<Magnetic Characteristics—Magnetic Attraction Force>
Cut out the magnetic sheet to 100mm x 100mm, paste the same resin plate as the sheet on the back side of the magnetic attraction surface with adhesive, magnetically attach it to a horizontally fixed 0.5mm thick steel plate, and vertically above the steel plate The minimum peeling force at the time of peeling was measured with a spring balance, and (peeling force-(sheet weight + adhesive weight + resin plate weight))
/ Sheet area = magnetic attraction force.

The magnetic attraction force of the permanent magnet can be magnetically attracted to a vertical surface in a stationary state if the magnetic attraction force is three times or more its own weight empirically. However, disturbance (vibration, shock, (E.g. wind pressure of indoor air conditioning). It is said that if it has a magnetic attraction force ten times or more its own weight, it can also be attracted to disturbance. The evaluation was satisfactory when the magnetic attraction force when the sheet weight was 1 was 10 or more, and was unsatisfactory when the magnetic attraction force when the sheet weight was 1 was less than 10.

<Curl> After drying in the sheet preparation step, the sheet was visually checked for curl. Evaluation,
If the curl was 7 mm or less, it was judged to be satisfactory. If the curl was larger than 7 mm, it was judged unsatisfactory.

Table 4 below shows the evaluation results of the magnetically attracting sheets of the samples of Examples 1 to 9 and Comparative Examples 1 to 8 which were evaluated as described above.

[0053]

[Table 4]

According to Table 4, as shown in Examples 1 to 9, the conventional magnetic adsorption sheet A was coated with a cellulose acetate resin having a dry film thickness of 0.5 to 5 μm or the cellulose acetate resin had a particle size of 0.5 to 5 μm. When the organic pigment of about 10 μm is contained in an amount of 5 to 20 parts by weight based on 100 parts by weight of the cellulose acetate-based resin, the sheet has excellent adhesion resistance, and has good results in various evaluations such as dusting resistance during printing. Obtained. Further, when the protective layer contained an organic pigment having an average particle size of 5 to 20 μm, the sheet had excellent adhesion resistance, and good results were obtained in various evaluations such as powder fall resistance during printing.

Further, as shown in Comparative Example 1, when a polyurethane resin is used as a protective agent instead of a cellulose acetate resin, the glass transition temperature Tg is as low as 80 ° C., so that it can be used as a magnetic adsorption sheet for a long time. It was found that when it was adsorbed on a hot display such as a pot, it was sticky.

Furthermore, as shown in Comparative Example 2, when an acetal resin was used as a protective agent, the glass transition temperature Tg was 110 ° C., so that sticking of the magnetically attracted surface could be prevented. However, it was found that the sheet was curled during drying due to the drying stress due to the strong cohesive force of the resin. Therefore, sticking can be prevented by using a resin having a glass transition temperature Tg of 110 ° C. or higher. In addition, curl of the sheet can be prevented by using a resin having a low cohesive force.

Further, as shown in Comparative Examples 3 and 4,
If the amount of the particles exceeds 50 parts by weight, the particles cannot be sufficiently dispersed, and it is difficult to form a coating film. Even if it can be formed, the coating film will be brittle, the adhesive strength will be reduced, and the powder will fall off during printing. Therefore, it was found that the amount of added particles is preferably in the range of 20 parts by weight or less.

Further, as shown in Comparative Example 5, even when the particle diameter exceeds 20 μm, the particles cannot be sufficiently dispersed, and it is difficult to form a coating film. Even if it can be formed, the coating film becomes brittle, the adhesive strength is reduced, and powder is dropped during printing. For that reason,
It was found that the particle diameter was desirably 20 μm or less.

Further, as shown in Comparative Example 6, when the thickness of the protective layer is less than 0.5 μm, coating unevenness occurs at the time of coating and the magnetic layer cannot be covered sufficiently. As a result, the sheet sticks and powder drops during printing.

When the thickness of the protective layer is larger than 5 μm as shown in Comparative Example 7, not only fine foaming is liable to occur when the protective layer is dried, but also the magnetic properties are deteriorated because the thickness is too large. . From this, it was found that the thickness of the protective layer is preferably set to 0.5 to 5 μm. Therefore, by setting the thickness of the protective layer to 0.5 to 5 μm, the tack resistance, the adhesive strength, and the magnetic properties can be improved.

As shown in Comparative Example 8, when the protective layer was not formed on the magnetic layer, the sheet was stuck and powder fell during printing.

As described above in detail, the magnetic adsorption sheet 1 of the present invention contains a predetermined amount of a cellulose acetate resin, and a predetermined amount of a predetermined amount of particles in a predetermined amount of the cellulose acetate resin. It is a paint that is coated on a magnetically adsorbing sheet so that it has a predetermined film thickness, so it has excellent anti-adhesion and powder-drop resistance, and can be printed on ordinary copiers and printers. An adsorption sheet can be manufactured.

As described above, according to the present embodiment, since the protective layer having anti-adhesion is formed, the magnetically attracted sheet printed by a general copying machine or printer is attracted to the same place for a long time. It can also be adsorbed on a hot display such as a pot. In addition, since the protective layer is formed, the powder has excellent resistance to dusting, and can be continuously printed by a general copying machine or printer.

[0064]

The present invention has the following effects. Since a protective layer with anti-adhesion is formed, magnetically attracted sheets printed by ordinary copiers and printers can be attracted to the same place for a long time, or can be attracted to pots such as pots that are heated. It is possible. In addition, since the protective layer is formed, the powder has excellent resistance to dusting, and can be continuously printed by a general copying machine or printer.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the invention relating to a magnetic attraction sheet for display.

[Explanation of symbols]

1) magnetic attraction sheet for display, 2) non-magnetic recording medium,
3 recording layer (printing ink receiving layer), 4 non-magnetic support, 5 magnetic layer, 6 protective layer

Continuation of front page (56) References JP-A-10-24534 (JP, A) JP-A-11-121219 (JP, A) JP-A-57-8922 (JP, A) JP-A-5-185772 (JP) , A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 H01F ^7/ 00-7/24

Claims (2)

(57) [Claims] 1. A non-magnetic support comprising: a non-magnetic support; and a magnetic layer formed by applying and drying a magnetic paint containing a ferromagnetic powder and a polymer binder as main components on the non-magnetic support.
And the axis of easy magnetization of the ferromagnetic powder in the magnetic layer is
Oriented in-plane with respect to and multi-pole magnetized in-plane
The magnetic layer thus formed , and adhesion and peeling of the magnetic layer formed on the surface of the magnetic layer.
A protective layer for preventing separation, wherein the glass transition temperature Tg is 1
Mainly composed of cellulose acetate resin at 10 ° C or higher
And a protective layer having a thickness in the range of 0.5 to 5 μm . 2. The magnetic adsorption sheet according to claim 1, wherein the protective layer contains 5 to 20 parts by weight of particles having an average particle size of 5 to 20 μm based on 100 parts by weight of the cellulose acetate resin.