JP5280130B2 - Magnetic sheet material - Google Patents

Description

  The present invention relates to a magnetic sheet raw material that is used by being punched into a plurality of sheet pieces, and relates to a magnetic sheet raw material having small variations in magnetic properties.

  In recent years, a non-contact authentication system (RFID system) that reads and writes information between an IC tag and a reader / writer has been widely used. For example, in an electromagnetic induction type non-contact authentication system, the information is exchanged by magnetically coupling an antenna (coil) of an IC tag and an antenna (coil) of a reader / writer. In this case, the frequency of the electromagnetic wave used is typically 135 kHz or 13.56 MHz, for example.

  Here, the characteristics of the non-contact authentication system depend on the physical characteristics of the electromagnetic wave to be used. For example, in the non-contact authentication system using an electromagnetic wave having a frequency of 13.56 MHz, the magnetic field is affected by the metal present around the antenna. There is a problem that it is weakened and communication performance deteriorates.

  As a countermeasure against the failure caused by the metal as described above, a method of bypassing the magnetic flux by a magnetic sheet has been studied, and an antenna coil provided with a magnetic sheet such as a ferrite sheet is used. If a magnetic sheet is disposed between the antenna coil and the surrounding metal, the magnetic flux does not pass through the magnetic sheet and pass through the metal. As a result, loss due to eddy current does not occur and communication characteristics are improved.

  As the magnetic sheet, it is common to use a metal magnetic powder mixed with a resin and sheet it (metal resin composite sheet). There is a problem that the effective volume of the magnetic powder decreases. Usually, in the metal resin composite sheet, since the effective volume of the metal magnetic powder is only about 60%, the magnetic permeability of the magnetic sheet is lowered. The decrease in permeability leads to a decrease in the function of bypassing the magnetic flux, which leads to a decrease in communication characteristics.

  On the other hand, the use of a ferrite sintered body thin plate as a magnetic sheet has also been studied. The ferrite sintered body exhibits a permeability characteristic superior to that of the metal resin composite sheet in the bulk state, and has a high function of bypassing the magnetic flux. However, since the ferrite sintered body is not flexible, there is a problem that the degree of freedom of shape is low, and depending on how it is cracked, the magnetic permeability is greatly lowered, and the communication performance of the antenna is lowered. Furthermore, in the case of a ferrite sintered body, there is also a problem of debris and fine powder falling off when cracked.

  Under such circumstances, various methods for dividing the ferrite sintered body sheet (thin plate) have been studied in various directions (see, for example, Patent Document 1 to Patent Document 3).

  For example, Patent Document 1 discloses a sintered ferrite substrate in which an adhesive material layer is provided on at least one surface of a sintered ferrite plate, and the sintered ferrite plate is provided with at least one surface provided on at least one surface. A sintered ferrite substrate is disclosed which is configured to be separable starting from a continuous groove, and further, a protective layer is disclosed to be formed on the surface opposite to the adhesive material layer. The sintered ferrite substrate described in Patent Document 1 can be repeatedly affixed or peeled along a curved surface or an uneven surface of an electronic device, and it is said that there is little powder fall and a decrease in magnetic permeability.

  Patent Document 2 includes a ferrite sintered plate and a protective layer that adheres to at least one main surface of the ferrite sintered plate and covers the main surface. The ferrite sintered plate penetrates in the thickness direction and has both ends. A plurality of through-holes having substantially circular shapes are formed, and the plurality of through-holes are intermittently arranged on imaginary lines serving as starting points when the sintered ferrite plate is divided. Has been. In the invention described in Patent Document 2, by intermittently forming the through-holes, it is possible to deal with division and bending, and to prevent irregular cracks, chippings, spread of cracks, peeling from the protective layer, etc. It is supposed to be possible.

In Patent Document 3, a magnetic member formed in a sheet shape is placed on the surface of the adhesive layer, and stress is applied to the surface of the placed magnetic member to form the magnetic member into a plurality of magnetic solid pieces. In addition, a method for manufacturing a magnetic sheet is disclosed in which a protective layer having a resin as a main component and having a lower viscosity than a resin exposed to the outside is provided on the surface of a plurality of magnetic solid pieces. Has been. In the invention described in Patent Document 3, stress is applied to the entire surface of the magnetic member placed by a roller to pulverize the magnetic member into a plurality of magnetic solid pieces.
JP 2005-15293 A JP 2007-184492 A JP 2007-123575 A

  By the way, the above-mentioned magnetic sheet is usually used by preparing a magnetic sheet original fabric corresponding to the size of the sintered ferrite thin plate, punching individual sheet pieces therefrom, and bonding them to an antenna, for example. Therefore, it is desired that the difference in characteristics within the surface of the magnetic sheet original is small. If the characteristic difference in the plane of the magnetic sheet is large, the characteristic difference between the sheet pieces becomes large, and it is difficult to guarantee the quality of the product.

  From this point of view, sufficient results are not necessarily obtained with the above-described conventional technology. For example, even if a virtual dividing line is provided as in the inventions described in Patent Document 1 and Patent Document 2, direction dependency is expressed in the state of division, and the magnetic sheet original is not broken due to a problem that the virtual dividing line does not break. There is a current situation in which the characteristic difference in the plane increases in the opposite state.

  On the other hand, as in the invention described in Patent Document 3, in the method of applying stress to the entire surface of the sintered ferrite sheet with a roller and pulverizing it, it is difficult to regularly divide the sintered ferrite sheet, and the magnetic properties after pulverization are difficult. Since the body solid piece is indeterminate, the variation in characteristics within the surface of the magnetic sheet raw material becomes large, and the magnetic permeability is remarkably lowered.

  The present invention has been proposed in view of such a conventional situation, and the sintered ferrite thin plate is uniformly divided, and when used by punching into each sheet piece, there is a variation in characteristics between the sheet pieces. It aims at providing the magnetic sheet original fabric which can be suppressed.

Magnetic sheet raw of the present invention is a magnetic sheet raw to be punched into a plurality of sheet pieces, the resin film via the respective adhesive layers on both surfaces of the sintered ferrite sheet which is not imaginary dividing line is formed After the protective layer to be laminated , the sintered ferrite thin plate is sequentially divided from the portion where the deformation amount due to the bending exceeds the limit, so that the whole can be bent, and the divided pieces are divided. It is regularly divided so that the average value of the length of one side is 0.5 mm to 3 mm, and the deviation of the inductance of the divided pieces in the plane of the divided sintered ferrite thin plate is 3% or less. It is characterized by that. In the present invention, the protective layer is composed of a first protective layer made of a polyethylene terephthalate film having a pressure-sensitive adhesive layer on one side, and a second protective layer made of a polyethylene terephthalate film having a pressure-sensitive adhesive layer on both sides, A release paper is affixed to the outer surface of the second protective layer . In the present invention, the average value of the inductance of the divided pieces measured by bringing the antenna coil close to each other is 3.07 to 3.27 μH, and the punched sheet piece is used by being bonded to the antenna of the non-contact authentication system. It is characterized by being. The present invention is, overall size of that in a square is not less 50 mm × 50 mm or more, and that it is an aggregate of the split pieces of squares.

  In the present invention, for example, the dividing method of the sintered ferrite thin plate is made regular and uniform by devising the dividing method, and the deviation of the magnetic properties in the plane of the magnetic sheet original fabric is kept small. For this reason, the difference of the magnetic characteristic of each sheet piece after punching is suppressed, for example, variation in antenna characteristics is suppressed.

  According to the present invention, it is possible to provide a magnetic sheet original fabric in which the sintered ferrite thin plate is regularly divided at equal intervals, and the variation in the in-plane magnetic properties is small. Therefore, variation in characteristics can be suppressed when each sheet piece (magnetic sheet) is punched and used. For example, when the magnetic sheet is used while being bonded to the antenna of the non-contact authentication system, variations in antenna characteristics can be suppressed.

  Hereinafter, embodiments of a magnetic sheet original fabric to which the present invention is applied will be described with reference to the drawings.

  FIG. 1 schematically shows a basic cross-sectional structure of a magnetic sheet raw fabric 1. In the case of this example, the magnetic sheet original fabric 1 is configured by bonding the first protective layer 3 to one side of the sintered ferrite thin plate 2 and bonding the second protective layer 4 to the other side. Yes.

  The material of the sintered ferrite thin plate 2 is not limited as long as it is a soft ferrite having soft magnetic properties, and Ni—Zn ferrite or Mn—Zn is used depending on the required specifications such as a used frequency band and magnetic permeability. It is possible to freely select from ferrites and the like. The sintered ferrite thin plate 2 has a large magnetic permeability and a high magnetic permeability as compared with a metal resin composite sheet in which metal magnetic powder is mixed with a resin.

  The sintered ferrite thin plate 2 can be produced by a known method. For example, ferrite calcined powder, binder resin, additives (dispersant, plasticizer, antifoaming agent, etc.) and solvent are mixed, then defoamed and a doctor blade or the like placed on a support film (eg, polyethylene terephthalate film). And apply to produce a green sheet of ferrite. Subsequently, this is dried, and a baking process is performed at a predetermined temperature after the degreasing process. Although the thickness of the sintered ferrite thin plate 2 is arbitrary, it is, for example, about 20 μm to 0.3 mm.

  The first protective layer 3 bonded to one surface of the sintered ferrite thin plate 2 is a polyethylene terephthalate film 6 having an adhesive layer 5 on one surface, and the second protective layer 4 bonded to the other surface. Is a polyethylene terephthalate film 9 having adhesive layers 7 and 8 on both sides. The configuration of the first protective layer 3 and the second protective layer 4 is not limited to this, and can prevent the ferrite pieces from falling off and has an appropriate flexibility (flexibility). If it is. For example, the film functioning as a support is not limited to the polyethylene terephthalate film, and various resin films can be used. Alternatively, the first protective layer 3 and the second protective layer 4 may be formed of a double-sided pressure-sensitive adhesive tape, an adhesive layer, a resin paint layer, or the like. In this example, a release paper 10 is affixed to the surface of the adhesive layer 8 outside the second protective layer 4, and the release sheet 10 is peeled off so that the magnetic sheet 1 can be attached to any member. It can be pasted on.

  In the magnetic sheet original fabric 1 described above, the sintered ferrite thin plate 2 is regularly divided and divided into divided pieces 2c. FIG. 2 is a plan view of the divided sintered ferrite thin plate 2. In the magnetic sheet original fabric 1 of the present embodiment, the directions of the dividing lines 2a and the dividing lines 2b formed on the sintered ferrite thin plate 2 are aligned in parallel and are formed at equal intervals. Therefore, the distribution of variations in size and shape of each divided piece 2c is small, and variations in magnetic characteristics due to differences in the punching locations can be reduced.

  In the present invention, the variation in the magnetic characteristics is suppressed so that the deviation of the magnetic characteristics is 3% or less. For example, when the magnetic characteristics of the four corners of the magnetic sheet 1 are measured, if the deviation of each measured value is 3% or less, the characteristic difference between the sheet pieces is reduced to a level that does not cause a problem when punched into each sheet piece. It is possible to suppress. The magnetic characteristic to be measured is, for example, an inductance measured by bringing an antenna coil close to each other. When the inductance is measured at a plurality of locations on the magnetic sheet original fabric 1, the deviation may be 3% or less.

  Note that the deviation of the magnetic characteristics may vary depending on the size of the magnetic sheet raw fabric 1. In the present invention, 50 mm × 50 mm is set as a reference size, and the magnetic sheet deviation 1 larger than the reference size is required to have a deviation of 3% or less in the magnetic characteristics.

  In the magnetic sheet original fabric 1 described above, the smaller the size of the divided piece 2c after the division of the sintered ferrite thin plate 2, the smaller the variation in characteristics due to the difference in the punching location. If it becomes too small, there is a high possibility that the divided pieces 2c are not sufficiently held by the first protective layer 3 and the second protective layer 4, or that a problem of powder falling off from the end portion occurs at the time of punching. On the other hand, if the size of each divided piece 2c is too large, the amount of deviation from the parallel state of the dividing lines 2a and 2b increases, which tends to cause poor appearance, or the size distribution becomes large, resulting in variations in characteristics. There is a possibility that problems such as enlargement may occur.

  The optimum value of the size of the divided piece 2c depends on the size of the punched sheet piece, but the average length of one side is 0.5 mm to 5 mm. By dividing the sintered ferrite thin plate 2 by adjusting the size of each divided piece 2c to be within the above range, there is little variation in characteristics in the surface of the magnetic sheet raw fabric 1, and adhesion to the three-dimensional curved surface shape It can be set as the magnetic sheet excellent in property. For example, if the average length of one side of the divided piece 2c is 0.5 mm or more, there is a problem that the divided piece 2c is not sufficiently held by the adhesive layer, or the end portion of the magnetic sheet 1 is punched out. It is possible to avoid the problem of powder falling off. Further, if the average length of one side of the divided piece 2c is 3 mm or less, the deviation of the dividing line from the parallel direction can be suppressed, the appearance is deteriorated, or the variation in magnetic characteristics is increased. The trouble can be avoided.

  In the magnetic sheet original fabric 1 described above, it is necessary to devise a dividing method in order to make the magnetic property deviation 3% or less. Hereinafter, an example of a dividing method for reducing the variation in the magnetic characteristics of the magnetic sheet original fabric 1 will be described.

  FIG. 3 is a schematic diagram illustrating an apparatus configuration for the division process. The apparatus shown in FIG. 3 includes a belt-like support mechanism (pressure mechanism) 11 and a rotating roller 12, and the sintered ferrite thin plate 2 (magnetic sheet original fabric 1) is supported by the support mechanism 11. The sintered ferrite thin plate 2 is divided by running and changing the running direction of the support mechanism 11 along the curved surface.

  The belt-like support mechanism 11 can move (run) along the cylindrical surface of the rotating roller 12. A constant load spring 13 is provided at one end and a drive mechanism 14 is provided at the other end. is set up. The rotating roller 12 is, for example, a metal roller having a smooth cylindrical surface, and has a pressure mechanism that applies pressure toward the support mechanism 11. Moreover, the support mechanism 11 can raise a friction coefficient by making the material of the surface into a soft polyurethane, for example, and can prevent position shift and dropout.

  The belt-like support mechanism 11 is bent in the direction of 90 degrees by the rotating roller 12, and the traveling direction is changed by 90 degrees along a curved surface (a cylindrical surface of the rotating roller 12). Further, when the support mechanism 11 travels, tension is applied to the support mechanism 11 by the constant load spring 13, and the rotation roller 12 and the support mechanism 11 are coupled with the rotation roller 12 having a pressure mechanism. It is set as the structure which can apply a pressure to the magnetic sheet original fabric 1 (sintered ferrite thin plate 2) which moves between.

  As shown in FIG. 3, the division process of the sintered ferrite thin plate 2 is performed by supporting the magnetic sheet original fabric 1 by the above-described belt-like support mechanism 11 and running it.

  Note that, at the time of the division, the sintered ferrite thin plate 2 does not need to be formed with virtual dividing lines constituted by dividing grooves and slits, linearly arranged concave portions, through holes, and the like. This is because, when the apparatus shown in FIG. 3 is used for division, even division is not possible even if virtual division lines are not formed. Of course, it is also possible to form virtual dividing lines on the sintered ferrite thin plate 2 for the purpose of further even division. In the case of forming a virtual dividing line, the virtual dividing line may be any groove or slit, linear concave portion or through hole (so-called perforation hole), etc., as long as it can be easily divided. It may be.

  After the magnetic sheet original fabric 1 is attached to the support mechanism 11, the support mechanism 11 is caused to travel in the direction of the arrow. Then, the magnetic sheet original fabric 1 moves together with the support mechanism 11 and reaches the position of the rotary roll 12. At the installation position of the rotary roll 12, as shown in FIG. 4, the magnetic sheet original fabric 1 (that is, the sintered ferrite thin plate 2) also travels along the cylindrical surface of the rotary roll 12 together with the support mechanism 11. Bent in the direction of degrees. That is, by pulling up the support mechanism 11 by the drive 14, the magnetic sheet 1 passes between the rotary roll 12 and the support mechanism 11 in a state where pressure is applied from the back surface by the support mechanism 11. Bent in the direction of degrees.

  At this time, the magnetic sheet original fabric 1 moves on the rotary roll 12 between the rotary roll 12 and the support mechanism 11 while being pressed against the rotary roll 12, and the deformation amount due to bending exceeds the limit amount sequentially. The sintered ferrite thin plate 2 is divided and divided one after another. And as shown in FIG. 5, the division | segmentation in the running direction of the sintered ferrite thin plate 2 is completed because the magnetic sheet original fabric 1 passes between the rotary roll 12 and the support mechanism 11. FIG.

  After the one-way division (first division process) is completed as described above, the magnetic sheet original fabric 1 is attached to the support mechanism 11 by being rotated by 90 degrees, and the second division process is performed in the same manner. As shown in FIG. 2, when the original magnetic sheet 1 (that is, the sintered ferrite thin plate 2) is run in the direction of arrow A in the first division process, the rotation center axis direction of the rotary roll 12 [of the support mechanism 11 The dividing lines 2a in the traveling direction (direction orthogonal to the arrow A direction) are formed at equal intervals and divided into strips. In the second division process, if the vehicle is rotated 90 degrees and traveled in the direction of arrow B, the dividing line 2b in the direction of the rotation center axis of the rotary roll 12 [direction orthogonal to the travel direction of the support mechanism 11 (direction of arrow B)) Are formed at equal intervals, and the sintered ferrite thin plate 2 is divided into aggregates of square divided pieces 2c.

  According to the division process, the sintered ferrite thin plate 2 of the magnetic sheet 1 can be evenly divided and does not become indeterminate, so that magnetic properties such as magnetic permeability characteristics are uniform and good, and flexibility Can be obtained.

  The magnetic sheet original fabric 1 subjected to the above-described division processing is punched with a press machine or the like according to the shape specification of the RFID antenna, for example, and is attached to the antenna for use. If the above-described division processing is performed, even when a plurality of sheet pieces are punched from one magnetic sheet raw fabric 1 according to the antenna shape, there is a variation in characteristics between the sheet pieces due to the difference in the punching location. It has been confirmed that it is extremely small and variation in antenna characteristics can be reduced.

  The reason why a uniform division state of the sintered ferrite thin plate 2 can be realized in the plane of the magnetic sheet raw fabric 1 by the above-described method is that the stress is not concentrated on a limited point but is dispersed and acts in a wide area. This is considered to be because it is possible to suppress inadvertent division of the sintered ferrite thin plate 2 and to sequentially crack from the portion exceeding the deformation limit.

  In the apparatus shown in FIG. 3, the rotating roller 12 is used as a member constituting the curved surface. However, the present invention is not limited to this, and any member having an arcuate curved surface can be used. . For example, one in which one corner of a prism is processed into an arc surface, a plate material curved in an arc shape, or the like can be used.

  Further, a reference plate can be installed in order to reliably apply the pressure applied by the rotating roller 12 to the original magnetic sheet 1. FIG. 6 shows an apparatus structure in which a reference plate 15 whose position can be adjusted in the vertical direction is installed on the rotating roller 12 below. In this example, the gap amount t between the reference plate 15 and the belt-like support mechanism 11 can be adjusted by adjusting the position of the reference plate 15 in the vertical direction.

  For example, when the support mechanism 11 has elasticity, when the magnetic sheet raw fabric 1 passes between the rotary roll 12 and the support mechanism 11, the support mechanism 11 escapes in a direction away from the rotary roll 12, and the magnetic sheet original is removed. In some cases, a sufficient load is not applied to anti- 1, and the division of the sintered ferrite thin plate 2 may be hindered. In such a case, the reference plate 15 is provided, and as shown in FIG. 7, when the original magnetic sheet 1 passes between the rotary roll 12 and the support mechanism 11, the reference plate is provided from the back side of the support mechanism 11. If the structure is supported by 15, the pressing force of the rotary roll 12 is sufficiently applied to the magnetic sheet original fabric 1, and the sintered ferrite thin plate 2 can be reliably divided.

  In the division of the sintered ferrite thin plate 2 described above, factors such as the diameter and pressure of the rotating roller 12, the material of the cylindrical surface, and the amount of spring load of the constant load spring 13 at the end of the belt-like support mechanism 11 are adjusted. Thus, the size of the divided piece 2c after the division can be controlled.

  In the original magnetic sheet 1 of the present invention, the method for dividing the sintered ferrite thin plate 2 is not limited to the above method, and any method may be used as long as the deviation of the magnetic properties is 3% or less. It is possible to divide by this method.

  Next, specific examples of the present invention will be described based on experimental results.

Production of undivided magnetic sheet stock 1
The magnetic powder used in the preparation of the undivided magnetic sheet raw material in this example is made of Ni-Zn ferrite. Specifically, Fe ₂ O ₃ is 48 mol%, ZnO is 22 mol%, and NiO is used. It is a powder obtained by blending 22 mol% and CuO at a composition ratio of 8 mol% and pre-baking for 2 to 4 hours in the range of 700 ° C. to 900 ° C. To the Ni—Zn ferrite calcined powder having such a composition, an acrylic resin-based water-soluble binder, an antifoaming material, a dispersing agent, a plasticizer, and pure water were added and kneaded in a ball mill to prepare a slurry. The kneaded slurry was defoamed with a vacuum defoamer, and a sheet was formed on a polyethylene terephthalate (PET) film having a thickness of 100 μm using a doctor blade to produce a green sheet. The obtained green sheet was dried at 80 ° C. for 30 minutes with a dryer, and then the green sheet was cut into a predetermined shape and baked in the range of 1000 ° C. to 1100 ° C. for 2 to 5 hours, size 100 mm × 100 mm, thickness A sintered ferrite thin plate having a thickness of about 150 μm was obtained.

  Next, a polyethylene terephthalate film having an adhesive layer on one side is attached to one side of the obtained sintered ferrite thin plate as a protective layer made of the first resin material, and the other side is protected by the second resin material. As a layer, a polyethylene terephthalate film having an adhesive layer on both sides was pasted to prepare an undivided magnetic sheet original fabric A.

Division 1
According to the apparatus and method shown in FIGS. 3 to 5, the sintered ferrite thin plate was divided for the produced undivided magnetic sheet original fabric A (Examples 1 to 4). In each example, the sintered ferrite thin plate was divided by changing the diameter and surface material of the rotating roll and the tension (constant load spring load) applied to the support mechanism. For comparison, the sintered ferrite thin plates were divided by abutting and rolling the rotating roller on the undivided magnetic sheet original fabric (Comparative Examples 1 and 2).

  For each magnetic sheet raw material after the division, the impedance characteristic was measured by bringing the RFID antenna coil close to the magnetic sheet as the magnetic characteristic evaluation. The antenna coil has a rectangular shape with an outer diameter of 40 mm × 30 mm, and is made of a flexible flat cable having 5 turns. Using this antenna coil, an inductance L of 13.56 MHz was measured with an impedance analyzer. With respect to the magnetic sheet original fabric (100 mm × 100 mm), the antenna position was changed in the sheet plane and measured at four locations, and the average value and deviation [(maximum value−minimum value) / average value] of these data were obtained. Further, the size of the divided pieces (divided pieces) of each magnetic sheet was determined from the number of dividing lines per length. The average divided piece size is indicated by the length of one side assuming a square. The results are shown in Table 1.

  Hereinafter, each Example and a comparative example are explained in full detail.

Example 1
In this embodiment, a metal roller having a diameter of 20 mm was used as the rotating roller, and the constant load spring at the end of the belt-like support mechanism was divided into 20N. In the magnetic sheet original fabric after the division, the division lines were formed in a straight line, and were substantially parallel and evenly spaced. In addition, the average divided piece size in the magnetic sheet original fabric after the division was 1.0 mm, and the unevenness on the surface was not conspicuous, and it was possible to curve smoothly and uniformly in the plane. Further, in the evaluation of the inductance L of the antenna, it was possible to realize a state in which the average value was as large as 3.27 μH and the deviation was as small as 0.6%.

(Example 2)
In this embodiment, the constant load spring at the end of the belt-like support mechanism has a spring load of 2N, and the others are divided under the same conditions as in the first embodiment. In the original magnetic sheet after division, the dividing lines were formed in a straight line, and were substantially parallel and evenly spaced, as in Example 1. However, the interval was widened and the average divided piece size was 1. It became 8 mm. Further, the magnetic sheet original fabric after the division was not conspicuous on the surface, and could be smoothly and uniformly curved in the plane. Further, in the evaluation of the inductance L of the antenna, it was possible to realize a state in which the average value was 3.22 μH and the deviation was as small as 0.9%.

(Example 3)
In addition to the conditions of Example 2, a 6 mm-thick silicon rubber (Shore A50) was wound around the metal roller to change the cylindrical surface material, and the others were divided in the same manner as Example 2. In the magnetic sheet raw material after the division, the dividing lines were formed in a straight line, were substantially parallel and evenly spaced, and the average divided piece size was 1.9 mm. Moreover, although the surface of the magnetic sheet after the division was larger than that of Example 2, the surface of the magnetic sheet was able to be uniformly curved in the plane. Further, in the evaluation of the inductance L of the antenna, it was possible to realize a state in which the average value was 3.21 μH and the deviation was as small as 1.2%.

Example 4
A metal roller with a diameter of 68 mm is used as the rotating roller, a 6 mm thick silicon rubber (Shore A50) is wound around the metal roller to change the material of the cylindrical surface, and the spring load of the constant load spring at the end of the belt-like support mechanism is 20 N Divided. In the magnetic sheet raw material after the division, the dividing lines were formed in a straight line, were substantially parallel and evenly spaced, and the average divided piece size was 2.7 mm. Further, the magnetic sheet original fabric after the division had the same surface asperities as in Example 3, and could be uniformly curved in the plane. Further, in the evaluation of the inductance L of the antenna, an average value was 3.25 μH, and the deviation was as small as 1.2%.

(Comparative Example 1)
A 6 mm thick silicon rubber (Shore A50) was laid as a buffer material on the metal plate, and the produced magnetic sheet was installed. A metal roller having a diameter of 20 mm was placed thereon as a rotating roller having a smooth cylindrical surface, and the sintered ferrite thin plate was divided by moving it parallel to the magnetic sheet while applying a load of 20N. The dividing line is formed in a direction close to the rotation center axis direction of the rotating roller, but a part of the dividing line is largely deviated and formed obliquely. It was in a state where unevenness was seen in the interval. Moreover, although the average division | segmentation piece size was 1.8 mm, it was in the state by which the size and the shape were seen in the magnetic sheet original fabric. Furthermore, the surface of the original magnetic sheet after the division was in a state where the irregularities could be clearly confirmed. Although it was possible to bend, the curvature within the original magnetic sheet was not uniform. Furthermore, in the evaluation of the inductance L of the antenna, the average value was 3.22 μH, but the deviation was 3.1% and the variation was large.

(Comparative Example 2)
As a rotating roller, a 6 mm thick silicon rubber (Shore A50) was wound around a metal roller having a diameter of 68 mm, and the cylindrical surface material was changed, and the sintered ferrite thin plate was divided in the same manner as in Comparative Example 1. . The dividing line is formed in a direction close to the rotation center axis direction of the rotating roller, but a part of the dividing line is largely deviated and formed obliquely. It was in a state where unevenness was seen in the interval. Moreover, although the average division | segmentation piece size was 3.3 mm, it was in the state by which the size and the shape were seen in the magnetic sheet original fabric. Furthermore, the surface of the original magnetic sheet after the division was in a state where the irregularities could be clearly confirmed. Furthermore, in the evaluation of the inductance L of the antenna, the average value was 3.21 μH, but the deviation was 4.2% and the variation was large.

  As described above, in Examples 1 to 4 to which the present invention is applied, the divided magnetic sheets can be uniformly bent with a constant curvature radius, and the sintered ferrite thin plate is in a predetermined divided state. It was confirmed that variation in magnetic characteristics (inductance) in the magnetic sheet can be suppressed to 3% or less. On the other hand, in Comparative Examples 1 and 2, the directions and intervals of the dividing lines were not uniform in the magnetic sheet, the size of the divided pieces varied greatly, and the variation in magnetic characteristics exceeded 3%.

Production of undivided magnetic sheet stock 2
To an Ni-Zn ferrite calcined powder having the same composition as that of Preparation 1 of undivided magnetic sheet raw material, an acrylic resin-based water-soluble binder, an antifoaming material, a dispersing material, a plasticizer, and pure water are added to a ball mill. And kneaded to prepare a slurry. The kneaded slurry was defoamed with a vacuum defoamer, and a sheet was formed on a polyethylene terephthalate (PET) film having a thickness of 100 μm using a doctor blade to produce a green sheet. The obtained green sheet was dried at 80 ° C. for 30 minutes with a dryer, and then the green sheet was cut into a predetermined shape and baked in the range of 1000 ° C. to 1100 ° C. for 2 to 5 hours, size 100 mm × 100 mm, thickness A sintered ferrite thin plate having a thickness of about 100 μm was obtained.

  Next, a polyethylene terephthalate film having an adhesive layer on one side is attached to one side of the obtained sintered ferrite thin plate as a protective layer made of the first resin material, and the other side is protected by the second resin material. As a layer, a polyethylene terephthalate film having an adhesive layer on both sides was pasted to prepare an undivided magnetic sheet original fabric B.

Division 2
As shown in FIG. 6 and FIG. 7, the gap between the reference plate and the support mechanism is adjusted using the apparatus in which the reference plate is installed, and the sintered ferrite thin plate is divided for the produced undivided magnetic sheet original fabric B (Example 5 to Example 9, Comparative Example 3). In each example, the sintered ferrite thin plate was divided by changing the diameter and surface material of the rotating roll and the tension (constant load spring load) applied to the support mechanism.

  About the magnetic sheet raw material after the division, the same magnetic property evaluation as the division 1 was performed, and the size of the divided piece (divided piece) of each magnetic sheet was obtained from the number of dividing lines per length. . The average divided piece size is indicated by the length of one side assuming a square. The results are shown in Table 2.

  Hereinafter, each Example and comparative example in this division | segmentation experiment are explained in full detail.

(Example 5)
In this embodiment, a metal roller having a diameter of 20 mm is used as the rotating roller, the spring load of the constant load spring at the end of the belt-like supporting mechanism is 20 N, the rotating roller pressure is 0.2 MPa, and the gap amount between the reference plate and the supporting mechanism is 0. Splitting was performed at 35 mm. In the magnetic sheet original fabric after the division, the division lines were formed in a straight line, and were substantially parallel and evenly spaced. In addition, the average divided piece size in the magnetic sheet original fabric after the division was 0.9 mm, and the surface unevenness was not conspicuous, and it was possible to curve smoothly and uniformly in the plane. Further, in the evaluation of the inductance L of the antenna, an average value of 3.13 μH and a deviation of 1.0% were realized with a small variation.

(Example 6)
In this example, the diameter of the rotating roller was changed to 50 mm, and the other division was performed under the same conditions as in Example 5. In the original magnetic sheet after division, the dividing lines were formed in a straight line, and were substantially parallel and evenly spaced, as in Example 1. However, the interval was widened and the average divided piece size was 1. It became 5 mm. Further, the magnetic sheet original fabric after the division was not conspicuous on the surface, and could be smoothly and uniformly curved in the plane. Further, in the evaluation of the inductance L of the antenna, it was possible to realize a state in which the average value was 3.13 μH and the deviation was as small as 1.3%.

(Example 7)
In this example, the diameter of the rotating roller was changed to 80 mm, and the other parts were divided under the same conditions as in Example 5. In the original magnetic sheet after the division, the dividing lines were formed in a straight line, were substantially parallel and evenly spaced, and the average divided piece size was 1.7 mm. The dividing line was slightly displaced from the parallel direction. Moreover, although the magnetic sheet original fabric after the division had larger surface irregularities than those of Examples 5 and 6, it could be uniformly curved in the plane. Further, in the evaluation of the inductance L of the antenna, it was possible to realize a state in which the average value was 3.13 μH and the deviation was as small as 1.6%.

(Example 8)
In this example, the cylindrical surface material of the rotating roller was changed to silicon rubber (Shore A50), and the others were divided under the same conditions as in Example 7. In the magnetic sheet raw material after the division, the dividing lines were formed in a straight line, were substantially parallel and evenly spaced, and the average divided piece size was 3.0 mm. The separation of the dividing line became more noticeable from the parallel direction. Moreover, the magnetic sheet original fabric after the division had the same surface irregularities as in Example 7, and could be uniformly curved in the plane. Furthermore, in the evaluation of the inductance L of the antenna, the average value was 3.14 μH, and the deviation was 2.3%, which was an allowable range of variation.

Example 9
In this example, the gap was 0.2 mm between the reference plate and the support mechanism, and the other divisions were performed under the same conditions as in Example 5. In the original magnetic sheet after the division, the dividing lines were formed in a straight line, and were substantially parallel and evenly spaced, as in Example 1, but the interval was narrowed, and the average divided piece size was 0.2 mm. It became 5 mm. Further, the magnetic sheet original fabric after the division was not conspicuous on the surface, and could be smoothly and uniformly curved in the plane. Further, in the evaluation of the inductance L of the antenna, an average value was 3.07 μH, and the deviation was 0.9%, and a state with a small variation could be realized. Also, in the state after punching into each sheet piece, the state where the divided pieces are not fixed with the adhesive material of the protective layer and not floating is not seen, and there is no problem with powder falling off from the end after punching .

(Comparative Example 3)
In this embodiment, a metal roller having a diameter of 80 mm is used as the rotating roller and the cylindrical surface material is silicon rubber (Shore A50), the spring load of the constant load spring at the end of the belt-like support mechanism is 6 N, and the rotating roller pressure is 0. The division was performed with a gap of 0.35 mm between the reference plate and the support mechanism. In the original magnetic sheet after the division, the dividing line was formed in a direction close to the rotational axis direction of the rotating roller, but a part of the magnetic sheet was formed to be largely shifted and slanted. In addition, unevenness was observed in the interval. Furthermore, the average divided piece size was as large as 4.5 mm, and there was a variation in size and shape within the sheet. Unevenness on the surface of the magnetic sheet original material after the division could be clearly confirmed. The magnetic sheet original fabric after the division could be uniformly curved in the plane. In the evaluation of the inductance L of the antenna, the average value was 3.14 μH, and the deviation was large with 5.4%.

  As described above, in each of Examples 5 to 9, the divided magnetic sheet original fabric can be uniformly bent with a constant radius of curvature, and a predetermined divided state is realized with respect to the sintered ferrite thin plate. It was confirmed that the variation in magnetic characteristics (inductance) in the magnetic sheet can be suppressed to 3% or less. On the other hand, in Comparative Example 3, the deviation of the variation in the magnetic characteristics exceeded 3% with the size of the divided pieces being large and the variation in the size distribution being large.

  From the results of Examples 5 to 9 and Comparative Example 3, when dividing the sintered ferrite thin plate, the size of the divided piece has an optimum range. For example, the average length of one side of the divided piece is 0.5 mm. By setting it as the above, it turned out that the problem that the holding | maintenance of a division | segmentation piece becomes inadequate or the powder fall from an edge part arises at the time of punching can be avoided. Moreover, if the average length of one side of the divided pieces can be suppressed to 3 mm or less, it is possible to avoid problems such as an increased amount of deviation from the parallel state of the dividing lines or appearance defects. It has been found that the variation in antenna characteristics (magnetic characteristics) can be avoided by increasing the distribution of the size of the divided pieces.

It is a schematic sectional drawing which shows the structural example of a magnetic sheet original fabric. It is a typical top view of the divided sintered ferrite thin plate. It is a schematic diagram which shows the example of an apparatus structure for dividing | segmenting a sintered ferrite thin plate. FIG. 4 is a schematic diagram showing a divided state of a sintered ferrite thin plate in the apparatus shown in FIG. 3. FIG. 4 is a schematic diagram showing a state after dividing a sintered ferrite thin plate in the apparatus shown in FIG. 3. It is a schematic diagram which shows the apparatus structural example which provided the reference | standard board. In the apparatus shown in FIG. 6, it is a schematic diagram which shows the division | segmentation state of a sintered ferrite thin plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetic sheet original fabric, 2 Sintered ferrite thin plate, 3 1st protective layer, 4 2nd protective layer, 5,7 Polyethylene terephthalate film, 6, 8, 9 Adhesive material layer, 10 Release paper, 11 Support mechanism, 12 rotation roller, 13 constant load spring, 14 drive mechanism, 15 reference plate

Claims (4)

A magnetic sheet raw to be punched into a plurality of sheet pieces, after the protective layer made of a resin film is bonded to each other via an adhesive layer on both surfaces of the sintered ferrite thin plate imaginary dividing line is not formed, The sintered ferrite thin plate is sequentially divided from the portion where the deformation amount due to the bending exceeds the limit, so that the whole can be bent, and the average value of the length of one side of the divided pieces is 0. The magnetic sheet material is characterized in that the sheet is regularly divided so as to have a thickness of 5 mm to 3 mm, and the deviation of inductance of the divided pieces in the plane of the divided sintered ferrite thin plate is 3% or less. . The protective layer is composed of a first protective layer made of a polyethylene terephthalate film having a pressure-sensitive adhesive layer on one side and a second protective layer made of a polyethylene terephthalate film having a pressure-sensitive adhesive layer on both sides. 2. The magnetic sheet original fabric according to claim 1, wherein release paper is attached to the outer surface of the layer . The average value of the inductance of the divided pieces measured by bringing the antenna coil close to each other is 3.07 to 3.27 μH, and the punched sheet piece is used by being bonded to the antenna of the non-contact authentication system. The magnetic sheet original fabric according to claim 1 or 2, characterized in that: Whole is in the size of its is 50 mm × 50 mm or more square magnetic sheet raw thing according to any one of claims 1, wherein 3 a which is an aggregate of the split pieces of the square anti.

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