JP3326690B2 - Magnetic adsorption sheet for display - Google Patents

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 obtained by applying a coating mainly composed of a ferromagnetic powder and a polymer binder onto a non-magnetic support.

[0002]

2. Description of the Related Art Magnetic attraction sheets utilizing the 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 an increasing desire to freely use those printed materials.

The first use of printed matter is to display. Various kinds of adhesives,
A fixing material such as an adhesive tape, a thumbtack, or a cap magnet is used. Since the display object of the magnet sheet itself is a fixing material having a magnetic attraction property, when the posting place is a ferromagnetic surface, it can be displayed alone without requiring another fixing material.

[0005] The magnet sheet is a sheet-like bonded magnet, and as its use is expanded, its thickness is reduced so that it can be easily processed. Conventionally, the minimum thickness of sheet processing by compression molding was limited to 0.4 mm, so it was not possible to respond with a general-purpose printing machine, and printing processing had to be ordered by a specialized manufacturer. A magnet sheet having a thickness of 0.2 mm or less has been put to practical use, and printing has finally become possible with a general-purpose printer.

[0006]

In all of the conventional magnet sheets, the magnetic material is oriented so that it has an easy axis of magnetization in a direction perpendicular to the magnetic layer, and the magnetization is also magnetized in the same direction. The magnetic flux density of the permanent magnet increases as the distance between the magnetic poles increases. However, in the case of a vertically magnetized magnet sheet, the distance between the magnetic poles = film thickness. Density decreases. The production of a magnet sheet by a plastic molding method requires a large-scale facility because a paste obtained by kneading a powdery magnetic material and a binder is processed under high temperature and high pressure. Furthermore, plastic molding is more difficult as the film thickness is reduced, and the load on the equipment is increased.

In view of these circumstances, a method has been devised for providing a thinner magnetic attraction sheet with a smaller load on manufacturing equipment.

An object of the present invention is to form a magnetic layer having an easy axis of magnetization in the in-plane direction using a magnetic paint containing a ferromagnetic powder and a polymer binder as main components, and perform in-plane magnetization. A thin-film magnetic attraction sheet for display is provided.

[0009]

According to the magnetic attraction sheet for display of the present invention, a magnetic coating mainly composed of a ferromagnetic powder and a polymer binder is applied to a non-magnetic support and dried to form a magnetic layer. In the display magnetic attraction sheet to be formed, the squareness ratio calculated from the magnetization curve of the magnetic layer in the in-plane magnetic field with respect to the magnetic layer is 80% or more and 92% or less .
This is a magnetic attraction sheet for display, in which the axis of easy magnetization of the ferromagnetic powder in the magnetic layer is oriented and multipolarly magnetized alternately so as to be polarized in an in-plane direction.

[0010]

[0011]

[0012]

Further, the magnetic attraction sheet for display of the present invention comprises:
The thickness of the magnetic layer is 0.03 mm or more and 0.15 mm or less, and the total thickness including the nonmagnetic support is 0.08 mm or more and 0.2
5 mm or less, and the ratio of the binder in the magnetic layer is 8 to 18 parts by weight based on 100 parts by weight of the ferromagnetic powder, and can be printed by a general home copying machine or printer. .

According to the magnetic attraction sheet for display of the present invention,
In order that the squareness ratio calculated from the magnetization curve of the magnetic layer in the in-plane magnetic field with respect to the magnetic layer is 80% or more,
Since the axis of easy magnetization of the ferromagnetic powder in the magnetic layer is oriented and alternately multipolar magnetized so as to be polarized in the in-plane direction, the distance between the magnetic poles can be sufficiently secured even if the magnetic layer is thinned,
Demagnetizing field does not increase and demagnetization is difficult. The magnetic layer whose easy axis is in the in-plane direction is subjected to multipolar magnetization in the easy axis direction, so that a maximum leakage flux in the vertical direction is generated from the opposing magnetic pole surface.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention relating to a magnetic attraction sheet for display will be described. The problem is that a magnetic paint mainly composed of a ferromagnetic powder and a polymer binder is applied to a non-magnetic support 8 as shown in FIG. 1 and dried to form a magnetic layer 9 for display. In the sheet, the easy axis of magnetization of the ferromagnetic powder in the magnetic layer is oriented such that the squareness ratio calculated from the magnetization curve of the magnetic layer in the in-plane magnetic field with respect to the magnetic layer 9 is 80% or more. The problem is solved by the magnetic attraction sheet for display 10 which is alternately multipolar magnetized so as to be polarized in the in-plane direction.

The ferromagnetic powder used in the present invention includes:
For example Ba ferrite powder, the ferromagnetic iron oxide such as Sr ferrite powder can ani gel.

As the polymer binder for dispersing such ferromagnetic powder, thermoplastic and thermosetting resins are used. The resin suitably 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,
Organic polymer materials such as acrylic resin, polyester resin, and polyurethane resin. These may be used alone or in combination of several kinds of resins.

The ratio of the binder in the magnetic layer is as follows:
It is preferably 8 to 18 parts by weight based on 00 parts by weight. 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 easily causes 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 magnetic adsorption sheet of the present invention is obtained by applying a coating material obtained by sufficiently dispersing ferromagnetic particles in a polymer binder and a solvent onto a non-magnetic support with a gravure coater, a die coater, a knife coater or the like. Made by The coated support passes through an orientation magnetic field so that the easy axis of magnetization of the ferromagnetic powder is oriented in the in-plane direction, and further passes through a hot-air dryer, whereby the solvent in the paint evaporates and is dried and solidified. Thus, a coating film of the magnetic adsorbent is formed.

Thus, a thin magnetic layer can be formed continuously without using high-temperature and high-pressure equipment such as extrusion molding.

In order to continuously orient the magnetic axis of the easy axis of the ferromagnetic powder in the coating in the in-plane direction of the coating, the support immediately after coating is passed through a magnetic field having a magnetic flux parallel to the traveling direction of the support. You can do it. Examples of the means include a method of passing through a solenoid as shown in FIG. 2 and a method of generating a magnetic flux in the traveling direction of the support by repelling a permanent magnet from the front and back of the support as shown in FIG. There is a method of passing through the space.

As shown in FIG. 4, the magnetic layer whose easy axis is in the in-plane direction has (N−S) (S−S) in the easy axis direction.
N) (N−S)} multipolar magnetization gives S−
A maximum vertical leakage magnetic flux is generated from the opposing magnetic pole surface of S or NN, and the magnetic attraction force can be effectively exerted between the magnetic flux surface and a ferromagnetic wall surface such as steel.

In the in-plane orientation of the easy axis of the magnetic layer, the squareness ratio calculated from the in-plane magnetization curve is preferably 80% or more. If it is less than 80%, the residual magnetic flux density after magnetization is insufficient, and a sufficient magnetic attraction force cannot be obtained.

In the case of the conventional perpendicular orientation and perpendicular magnetization as shown in FIG. 5, the distance between the magnetic poles decreases and the demagnetizing field increases as the film thickness decreases. In the case of in-plane magnetization, since the distance between magnetic poles can be sufficiently secured even if the magnetic layer is made thin, the demagnetizing field does not increase and demagnetization is difficult. Further, at the time of magnetic attraction, the object to be attracted becomes a yoke, the magnetic circuit is almost completely closed, and the leakage magnetic flux is extremely small.

The thickness of the magnetic layer is 0.03 mm or more and 0.1
5 mm or less is desirable. Since the magnetic energy of the permanent magnet is proportional to the volume of the magnet, if the film thickness is less than 0.03 mm, a magnetic attraction force sufficient to stably fix the weight of the magnetic layer + the support to the vertical adsorption surface cannot be obtained. . Further, the film thickness is 0.
If the thickness is more than 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.

The non-magnetic support used in the present invention may be a coated paper having a resin-coated surface so as to prevent the solvent from penetrating into the back surface of the magnetic paint-coated surface, a synthetic paper, or a white paper for the purpose of applying a magnetic paint. Synthetic films are preferred. As a specific example, a white polyester film or the like having a surface subjected to an easy adhesion treatment can be given.

On the non-magnetic support, a heat-sensitive layer, a thermal transfer ink receiving layer, an ink jet receiving layer, a bubble jet (registered trademark) receiving layer, a dot impact receiving layer, a laser printer toner receiving layer are provided on the surface opposite to the surface coated with the magnetic paint. It is possible to add a functional layer according to a printing method such as the above, and a receiving layer according to a display purpose and a printing method can be appropriately selected.

The total thickness of the magnetic attraction sheet for display according to the present invention is desirably 0.08 mm or more and 0.25 mm or less. In such a case, the thickness of the nonmagnetic support including the printing receiving layer provided on the display surface is desirably 0.05 mm or more. If the thickness of the support is less than 0.05 mm, the color of the magnetic layer is transparent on the surface of the support when used for display and printing purposes, so that the display appearance is deteriorated. Here, the lower limit of the total thickness is set to 0.08 mm because the lower limit of the thickness of the magnetic layer is 0.03 mm and the lower limit of the thickness of the nonmagnetic support is 0.05 mm. 0.08mm
This is because On the other hand, if the maximum total thickness including the magnetic layer exceeds 0.25 mm, it falls outside the range that can be accommodated by a general home copying machine or printer.

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]

EXAMPLES The magnetic attraction sheet of the present invention and its effects will be specifically described below.

Example 1 The components shown in Table 1 were mixed in a ball mill and uniformly dispersed to prepare a magnetic paint. A curing agent (trade name:
After adding 0.3 parts by weight of Coronate HL (manufactured by Nippon Polyurethane Co., Ltd.), using a knife coater, the base material: white synthetic paper with an ink jet-compatible receiving layer (thickness: 0.08 mm) (trade name: TOYOJET (manufactured by Toyobo Co., Ltd.) )) Is applied to the back side of the printing surface, and the in-plane orientation magnetic field 2k is formed by the same polarity of the permanent magnet.
After passing through G, in-plane orientation was performed, followed by drying to obtain a raw material having a magnetic layer thickness of 0.05 mm and a total thickness of 0.13 mm.

After the obtained raw material is stored in a 60 ° C. environment for at least 20 hours and cured, as shown in FIGS. 6 and 7, the multi-polarized magnet is alternately polarized so as to be polarized in the in-plane direction. Magnetic pole width 2.0 mm), that is,
A large number of poles were arranged alternately in the order of pole-S-pole-N-pole, and the space between them was subjected to multipolar magnetization in which a magnetic layer was passed to obtain a magnetically attractable sheet.

[0033]

[Table 1]

Example 2 A magnetically attractable sheet having a total thickness of 0.11 mm was obtained in the same manner as in Example 1 except that the dry thickness of the magnetic layer was changed to 0.03 mm.

Example 3 Example 1 was repeated except that the in-plane alignment magnetic field was changed to 0.7 kG.
In the same manner as in the above, a magnetic adsorption sheet having a total thickness of 0.13 mm was obtained.

Example 4 A magnetically attractable sheet having a total thickness of 0.11 mm was obtained in the same manner as in Example 2 except that the amount of the polymer binder was changed to 8 parts by weight.

Example 5 Example 2 except that the polymer binder was changed to 18 parts by weight.
In the same manner as in, a magnetic attraction sheet having a total thickness of 0.11 mm was obtained.

Example 6 A magnetically attractable sheet having a total thickness of 0.18 mm was obtained in the same manner as in Example 1 except that the dry thickness of the magnetic layer was changed to 0.10 mm.

Example 7 A magnetically attractable sheet having a total thickness of 0.23 mm was obtained in the same manner as in Example 1 except that the dry film thickness of the magnetic layer was changed to 0.15 mm.

Example 8 The coating base material was 0.10 mm thick white synthetic paper with an ink jet-compatible receiving layer, and the dry thickness of the magnetic layer was 0.15 m.
A magnetically attractable sheet having a total thickness of 0.25 mm was obtained in the same manner as in Example 6, except that m was changed to m.

Comparative Example 1 A magnetically attractable sheet having a total thickness of 0.10 mm was obtained in the same manner as in Example 1 except that the dry thickness of the magnetic layer was changed to 0.02 mm.

Comparative Example 2 Example 1 except that the in-plane alignment magnetic field was changed to 0.5 kG.
In the same manner as in the above, a magnetic adsorption sheet having a total thickness of 0.13 mm was obtained.

COMPARATIVE EXAMPLE 3 An N-pole and S-pole were alternately magnetized (magnetic pole width: 2.0 mm) on the surface on the magnetic attraction side of the raw material in which the in-plane orientation magnetic field of Example 1 was changed to the vertical orientation magnetic field. An adsorption sheet was obtained.

Comparative Example 4 In the same manner as in Comparative Example 3 except that the dry film thickness of the magnetic layer was changed to 0.03 mm, N and S poles were alternately magnetized on the surface on the magnetic attraction side (magnetic pole width 2. 0mm), the total thickness is 0.11m
m of the magnetically attractable sheet was obtained.

Comparative Example 5 A magnetic adsorption sheet having a total thickness of 0.13 mm was obtained in the same manner as in Example 1 except that the amount of the polymer binder was changed to 7 parts by weight.

Comparative Example 6 Example 1 except that the polymer binder was changed to 19 parts by weight.
In the same manner as in the above, a magnetic adsorption sheet having a total thickness of 0.13 mm was obtained.

Comparative Example 7 A magnetically attractable sheet having a total thickness of 0.24 mm was obtained in the same manner as in Example 1 except that the dry thickness of the magnetic layer was changed to 0.16 mm.

Comparative Example 8 A magnetically attractable sheet having a total thickness of 0.27 mm was obtained in the same manner as in Example 7, except that the coating base material was changed to a 0.12 mm thick white synthetic paper having an ink jet-compatible receiving layer. .

COMPARATIVE EXAMPLE 9 An N-pole / S-pole was alternately magnetized (magnetic pole width: 2.0 mm) on the surface on the magnetic attraction side of the raw material of Example 6 in which the in-plane orientation magnetic field was changed to the vertical orientation magnetic field. An adsorption sheet was obtained.

The squareness ratio and the magnetic attraction force of each of the examples and comparative examples were evaluated.

The squareness ratio was evaluated using a vibration type magnetic property measuring device (trade name: VSM (manufactured by Toei Kogyo KK)).

The evaluation of the magnetic attraction force was performed by using one magnetic attraction sheet.
Cut out to a size of 00mm x 100mm, affix a resin plate of the same shape as the sheet with an adhesive on the back side of the magnetic adsorption surface, magnetically adsorb it on a horizontally fixed 0.5mm thick steel plate, and peel off vertically above the steel plate The minimum peeling force at that time was measured with a spring balance, and (peeling force− (sheet weight + adhesive agent weight + resin plate weight)) / sheet area = magnetic attraction force.

Table 2 below shows the measurement results of the examples and the comparative examples.

[0054]

[Table 2]

The magnetic attraction force of the permanent magnet can be magnetically attracted to a vertical surface in a stationary state if the attraction force is three times or more of its own weight empirically. However, disturbance (external vibration, impact, indoor (E.g., air pressure of air conditioning). If it has a magnetic attraction force of 10 times or more of its own weight, it can be stably attracted to disturbance.

As in the example of the present invention, it can be confirmed that in the in-plane orientation / in-plane magnetization, sufficient magnetic attraction performance is obtained. First, the case where the magnetic layer thickness is 0.03 mm as in Example 2 and Comparative Example 4 will be described. The sheet weight / magnetic attraction force was 1/12 in Example 2 and 1/8 in Comparative Example 4. Thus, it can be seen that the in-plane orientation / in-plane magnetized sheet of Example 2 has a larger magnetic attraction force than the vertical orientation / perpendicular magnetized sheet of Comparative Example 4.

Next, the case where the thickness of the magnetic layer is 0.05 mm as in Example 1 and Comparative Example 3 will be described. The sheet weight / magnetic attraction force was 1/18 in Example 1 while 1/16 in Comparative Example 3. Thus, Embodiment 1
It can be seen that the in-plane orientation / in-plane magnetized sheet has a larger magnetic attraction force than the vertical orientation / perpendicular magnetized sheet of Comparative Example 3.

Next, the case where the magnetic layer thickness is 0.10 mm as in Example 6 and Comparative Example 9 will be described. The sheet weight / magnetic attraction force was 1/20 in Example 6 and 1/19 in Comparative Example 9. Thus, Embodiment 6
It can be seen that the in-plane orientation / in-plane magnetized sheet has a larger magnetic attraction force than the vertical orientation / perpendicular magnetized sheet of Comparative Example 9.

Next, the case where the magnetic layer thickness is 0.15 mm as in Example 7 or 8, and Comparative Example 8 will be described.
The sheet weight / magnetic attraction force was 1/2 in Example 7 or 8.
Comparative Example 8 is 1/21 compared to 2. Thus, it can be seen that the in-plane orientation / in-plane magnetized sheet of Example 7 or 8 has a larger magnetic attraction force than the vertical orientation / perpendicular magnetized sheet of Comparative Example 8.

On the other hand, as in Comparative Example 1, the magnetic layer thickness was 0.02.
mm, the adsorption power is small and stable adsorption cannot be expected. Also,
In the case of Comparative Example 7, when the thickness of the magnetic layer is 0.16 mm or more, a difference in elongation between the inside and outside of the coating due to bending cannot be tolerated, and cracks are easily generated in the coating due to repeated bending. From these facts, the thickness of the magnetic layer is 0.03 mm or more, 0.1
It is understood that 5 mm or less is desirable.

Next, the total thickness of Comparative Example 8 will be examined. The total thickness is 0.27 mm in Comparative Example 8. In the case of Comparative Example 8, the thickness exceeds the paper thickness that can be printed by a general home printing machine, and there is a possibility that a paper jam or other mechanical trouble may occur. This example is based on a commercially available inkjet printer (B
When printing was attempted with a J printer BJC-430 (manufactured by Canon Inc.) and Calario PM700C (manufactured by Seiko Epson Corporation), magnetic adsorption sheets other than Comparative Example 8 could be printed, but Comparative Example 8 could not be printed. Was. Looking at all the thicknesses other than the comparative example 8, the maximum value of the example 8 is 0.25 mm. From this, the total thickness of the magnetic attraction sheet for display is
It turns out that 0.25 mm or less is desirable.

On the other hand, the thickness of the nonmagnetic support including the receiving layer for printing provided on the display surface is desirably 0.05 mm or more.
If the thickness of the support is less than 0.05 mm, the color of the magnetic layer is transparent on the surface of the support when used for display and printing purposes, so that the display appearance is deteriorated. Further, as described above, since the lower limit of the thickness of the magnetic layer is 0.03 mm and the lower limit of the thickness of the nonmagnetic support is 0.05 mm, the total thickness of the magnetic attraction sheet for display is 0 mm. 0.08 mm or more is desirable.

In order to exert a sufficient magnetic attraction force, the orientation of the ferromagnetic powder is also important. Example 3 and Comparative Example 2
The alignment was performed by reducing the alignment magnetic field. The orientation magnetic field of Example 3
At 7 kG / square ratio of 80%, a suction force 10 times the sheet's own weight could be secured, but it was impossible with Comparative Example 2 at an orientation magnetic field of 0.5 kG / square ratio of 65%. This indicates that the squareness ratio is desirably 80% or more.

The magnetic properties change greatly even with the mixing ratio of the ferromagnetic powder and the polymer binder in the magnetic layer. If the ratio of the binder is as small as 8.0 parts by weight as in Example 4, the magnetic attraction force can be increased. However, if the binder is reduced to 7 parts by weight as in Comparative Example 5, the magnetic powder cannot be completely retained and cannot be held. Powder falls off the layer surface. Conversely, when the binder ratio is increased to 18.0 parts by weight as in Example 5, the magnetic attraction force decreases, and
If it is increased to parts by weight, the magnetic attraction force becomes insufficient. Also, if the amount of the polymer binder in the coating film composition is excessive, there is a possibility that the function of the magnetic adsorbent may be impaired that the adsorbing surface is adhered to the surface to be adsorbed by the binder and is detachable. . From these facts, the ratio of the binder in the magnetic layer is determined by the ferromagnetic powder 1
It is understood that the amount is preferably 8 to 18 parts by weight with respect to 00 parts by weight.

[0065]

The present invention has the following effects. The easy axis of the ferromagnetic powder in the magnetic layer is oriented so that the squareness ratio calculated from the magnetization curve of the magnetic layer in the magnetic field in the in-plane direction with respect to the magnetic layer is 80% or more. Since the magnetic poles are alternately polarized so as to be polarized in the directions, a magnetic attraction sheet for display having a stable magnetic attraction force and printable by a general home copying machine or printer can be provided.

[Brief description of the drawings]

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

FIG. 2 is an example of in-plane orientation of a magnetic powder by a solenoid.

FIG. 3 is an example of in-plane orientation of a magnetic powder by a permanent magnet of the same polarity facing magnetic field.

FIG. 4 is a model of multipolar magnetization and magnetic attraction of a magnetic layer having an easy axis of magnetization in an in-plane direction.

FIG. 5 is a model of multipolar magnetization and magnetic attraction of a magnetic layer having an easy axis of magnetization in a vertical direction.

FIG. 6 is a diagram showing a method of in-plane multipolar magnetization of a magnetic attraction sheet for display.

FIG. 7 is a diagram schematically showing a state of in-plane multipolar magnetization of a magnetic layer.

[Explanation of symbols]

1 magnetic field lines, 2 magnetic coating, 3 non-magnetic support,
4 in-plane oriented magnetic layer, 5 adsorbed body, 6 vertical oriented magnetic layer, 7 printing ink receiving layer, 8 non-magnetic support, 9 magnetic layer, 10 display Magnetic attraction sheet, 1
1 yoke

────────────────────────────────────────────────── ─── Continuing on the front page (72) Eiji Ota 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Miki Sudo 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo (56) References JP-A-11-273938 (JP, A) JP-A-58-178508 (JP, A) JP-A-8-213268 (JP, A) JP-A-10-24534 (JP JP, A) JP-A-6-309573 (JP, A) JP-A-8-1552859 (JP, A) JP-A-64-25504 (JP, A) JP-A-2000-25330 (JP, A) JP-A-2001 −6958 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01F 7/02 H01F 13/00 H01F 41/02 H01F 1/03-1/117

Claims (1)

(57) [Claims] 1. A non-magnetic support comprising: a non-magnetic support; and a magnetic layer formed by applying, orienting, and drying a magnetic paint containing a ferromagnetic powder and a polymer binder as main components on the non-magnetic support. The magnetic layer has a thickness of 0.03 mm or more and 0.15 mm or less, the magnetic layer has an in-plane squareness ratio of 80% or more and 92% or less, and is alternately polarized in the in-plane direction. Multi-pole magnetized and surface magnetic flux density between 32 Gauss (G) and 121 G
The total thickness including the non-magnetic support is 0.08 mm or more and 0.2
A magnetic attraction sheet having a thickness of not more than 5 mm and a binder content of 8 to 18 parts by weight based on 100 parts by weight of the ferromagnetic powder.