TW201545182A - Flexible magnetic attraction sheet and manufacturing method therefor - Google Patents

Abstract

A flexible magnetic attraction sheet has magnetic layers, respectively, on both surfaces of an adhesion layer, and resin sheet layers each provided on a surface on the reverse side to the adhesion layer of the magnetic layer, and is characterized in that the magnetic layer contains ferromagnetic powder and a binding agent, the Young's modulus in the thickness direction of the flexible magnetic attraction sheet is in the range of 70-400 kgf/cm2, and the Gurley stiffness is in the range of 1-20 mN. A flexible magnetic attraction sheet manufacturing method is characterized by comprising: a step for applying a magnetic paint to one surface of the resin sheet layer; a step for orienting ferromagnetic powder in the applied magnetic paint; a step for producing a laminated sheet (a) obtained by a step for providing the magnetic layer by drying a solvent in the magnetic paint; a step for producing a laminated sheet (b) obtained by bonding the magnetic layer surfaces of the laminated sheets (a); and a step for magnetizing both surfaces of the laminated sheet (b).

Description

Flexible magnetic adsorption sheet and method of manufacturing same

The present invention relates to a flexible magnetic adsorption sheet for display comprising a plurality of layers such as a magnetic layer and a resin sheet layer, and a method for producing the same.

The magnetic adsorption sheet which utilizes the magnetic attraction force of a magnet is widely used as a display sheet because it has a merit that it can be easily attached and removed without requiring a special fixing device as long as the display portion is a ferromagnetic surface.

The main magnetic sheets of the magnetic adsorption sheets are bond magnets which are thinned by compression molding or extrusion molding. In addition, since the performance of photocopiers, printers, etc. is improved, there is no need to rely on a specialist, and it is desirable to use a personal printer or the like to implement the printing of general or small units, and thus the magnetic thinning is relatively thin. The film has been put into practical use.

In addition, a magnetic adsorption sheet which optimizes the peeling resistance when the magnetic adsorbing sheet is subjected to the bending resistance and the adsorbed body to remove the adsorbed body is also invented (refer to Japanese Laid-Open Patent Publication No. 2012-138537). .

On the other hand, when a thin magnetic sheet is to be produced by a plastic molding method such as compression molding or extrusion molding, the powder is to be kneaded. The paste of the magnetic material and the binding agent is processed under high temperature and high pressure, so that the equipment is large-scale, and the more difficult the plastic forming system is to form a thin film, the burden on the device becomes large. In order to eliminate the above problem, it has been invented to form a magnetic layer by coating (refer to Japanese Laid-Open Patent Publication No. 2001-297910).

When excessive bending stress is applied to the magnetic adsorption sheet, the binder may be broken to cause cracks in the magnetic layer. Further, after the magnetic layer is magnetically adsorbed on the ferromagnetic surface or adsorbed at a high temperature for a long period of time, when the magnetic adsorption sheet is peeled off from the ferromagnetic material, at least a part of the magnetic layer is adsorbed on the surface of the ferromagnetic body. At this time, the magnetic layer of the magnetic adsorption sheet is not only destroyed but also contaminates the surface of the ferromagnetic body.

Moreover, the magnetic adsorption force of the permanent magnet is empirically known. If it has an adsorption force of 3 times or more of its own weight, it can be magnetically adsorbed on the vertical surface in a static state, but vibration, impact, wind, etc. from the outside. Under the influence of it, it will become easy to peel off. Therefore, it is important to suppress the weight of the magnetic adsorption sheet itself or to improve the adhesion to the adsorbed body in addition to maintaining the necessary magnetic force.

Further, as the magnetic adsorption sheet is made thinner, there is a problem that the magnetic adsorption sheet is curled when the magnetic adsorption sheet is produced or subjected to a high temperature experience. Such a magnetically adsorbed sheet which is curled may have a deterioration in display properties such as a decrease in the adsorption force of the adsorbed body or a peeling off.

On the other hand, when a special paper such as a magnetic adsorption sheet is printed by a printer or the like, generally, paper is usually supplied by a manual tray, and in order to perform multiple printing, it is necessary to frequently replenish the magnetic adsorption sheet, so There will be a lot of bad work.

In JP-A-2001-297910, a method of forming a magnetic layer by coating is described. However, when the coating film is thick, there is a large size of equipment due to the step of drying the solvent. It is a bad situation that the coating speed cannot be increased.

The present invention has been made in view of the above problems, and an object thereof is to provide a flexible magnetic adsorption sheet which has no curling, is not easily deformed, and is suitable for an adsorbed body, and a method for producing the same. The flexibility of sufficient adhesion can be achieved without causing adhesion to the surface to be adsorbed, light weight, high productivity in manufacturing, paper supply from the paper feed tray during printing, and excellent printability on both sides.

The present invention (1) is a flexible magnetic adsorption sheet having a magnetic layer on both sides of an adhesive layer, and a resin sheet layer having flexibility on each side of the magnetic layer opposite to the adhesive layer a magnetic adsorption sheet, characterized in that the magnetic layer comprises a ferromagnetic powder and a binder, and the Young's modulus of the flexible magnetic adsorption sheet in the thickness direction is 70 kgf/cm ² to 400 kgf/cm ² , and the Gore strength ( Gurley Intensity) is in the range of 1 mN to 20 mN.

The flexible magnetic adsorption sheet according to the invention (1), wherein the thickness of the adhesive layer is 10 to 20 μm, and the thickness of the resin sheet layer is 40 to 80 μm.

The flexible magnetic adsorption sheet according to the above aspect (1) or (2), wherein the resin sheet layer is polyethylene, polypropylene or polyethylene terephthalate having voids in the layer. Any of them.

The present invention (4) is the flexible magnetic adsorption sheet according to the above aspect (1), (2) or (3), wherein the adhesive constituting the adhesive layer is polyethylene or polypropylene, and the magnetic layer has a thickness of 30 ~60μm.

The flexible magnetic adsorption sheet according to the above aspect (1), (2) or (3), wherein the adhesive constituting the adhesive layer is a polyurethane, and the thickness of the magnetic layer is 40~80μm.

The flexible magnetic adsorption sheet according to the above aspect (1), (2), (3), (4) or (5), wherein the resin sheet layer is provided with an undercoat layer on both surfaces thereof.

The present invention (7) is the flexible magnetic adsorption sheet according to the above invention (1), (2), (3), (4), (5) or (6), which is coated on the resin sheet layer. The magnetic layers of the sheet coated with the magnetic layer follow each other.

The invention (8) is a method for producing a flexible magnetic adsorption sheet, comprising: a step of applying a magnetic coating on one surface of the resin sheet layer, and making the magnetic coating coating strong a step of aligning the magnetic powder, a step of producing the laminated sheet a obtained by the step of drying the solvent in the magnetic coating to form the magnetic layer, and a step of producing the laminated sheet b in which the magnetic layers of the laminated sheet a are adhered to each other And the step of magnetizing the both sides of the laminated sheet b.

According to the present invention, the Young's mode in the sheet thickness direction can be constituted by a layer having a magnetic layer on both faces of the adhesive layer and a resin sheet layer on each of the faces of the magnetic layer opposite to the adhesive layer. The number is 70kgf/cm ² to 400kgf/cm ² , and the Gurley strength is in the range of 1 mN to 20 mN, and a flexible magnetic adsorption sheet can be provided which has no curl even when subjected to high temperature, and is not easy to be obtained. The deformation and the flexible body can achieve sufficient flexibility for adhesion, and the adhesion to the surface to be adsorbed is not caused, and the productivity is high at the time of manufacture. Further, when the flexible magnetic adsorption sheet is printed by a printer or the like, it does not cause a problem in the passage of the paper from the paper feed tray, and the double-sided printability is also excellent.

Further, in the method for producing a flexible magnetic adsorption sheet according to the present invention, the laminated sheet a can be formed, and then the magnetic layers of the laminated sheet a can be bonded to each other to obtain a laminated sheet b, whereby the flexible magnetic property can be suppressed. The curl of the absorbent sheet. In other words, the laminated sheet a is produced in a continuous step, so that even if curling occurs, it is generally curled toward either the resin sheet side or the magnetic layer side, and the laminated sheet is obtained later. In the step b, the magnetic layer sides of the laminated sheets a are mutually connected, whereby the curl can be offset from each other even if the curl is generated upward. Further, it has an advantage that the flexibility and strength of the flexible magnetic adsorption sheet can be changed by controlling the material and thickness of the adhesive layer.

1‧‧‧Flexible magnetic adsorption sheet

2‧‧‧Next layer

3‧‧‧Magnetic layer

4‧‧‧resin sheet

41‧‧‧Substrate layer

42‧‧‧ film layer

43‧‧‧Undercoat

Fig. 1 is a view showing an example of a layer configuration of a flexible magnetic adsorption sheet of the present invention.

Fig. 2 is a view showing an example of the layer constitution of the resin sheet layer of the present invention.

Hereinafter, the embodiment of the present invention will be described by taking the flexible magnetic adsorption sheet 1 as an example, but the present invention is not limited thereto.

As shown in Fig. 1, the flexible magnetic adsorption sheet 1 of the present invention has a structure in which a magnetic layer 3 is provided on both sides of the adhesive layer 2, and further, a resin sheet layer 4 is provided on both sides thereof.

As shown in Fig. 2, the resin sheet layer 4 of the present invention is a base material layer 41, a film layer 42 provided on both surfaces of the base material layer 41, and a substrate layer on the film layer 42. The configuration of the undercoat layer 43 provided on each of the opposite sides of the opposite side 41 is preferable.

By adopting such a multi-layered laminated structure, it is possible to reduce the difference in curvature radius between the upper and lower layers in the respective layers which are generated when the flexible magnetic adsorption sheet is bent. Thereby, the strain due to the bending in the layer is reduced, and the flexible magnetic adsorption sheet 1 can be provided with excellent flexibility, and cracking/breaking in the layer can be prevented. Of particular importance is the presence of the adhesive layer 2 sandwiched by the magnetic layer 3 which is prone to cracking/breaking. By dividing the magnetic layer 3 into two, the resistance to the cracking or breaking can be increased, and the magnetic uniformity at the time of magnetization on both sides becomes good, and the layer thickness of the magnetic layer 1 can be thinned and the coating can be improved. The speed of application can also have the advantage of expected productivity improvement.

The ratio of each layer constituting the laminated structure in the thickness direction of the flexible magnetic adsorption sheet 1 is preferably about 0.03 to 0.35 when the entire flexible magnetic adsorption sheet 1 is regarded as 1, particularly in terms of an easy-to-produce layer. The portion of the magnetic layer of the inner crack is preferably 0.18 to 0.3.

Further, by not providing the magnetic layer 3 on the outermost surface, the printable layer can be disposed on both sides, and magnetic adsorption can be prevented after the magnetic layer 3 is magnetically adsorbed on the ferromagnetic surface for a long period of time. The phenomenon in which a part or all of the magnetic layer which occurs when the magnetic body is peeled off is adsorbed on the surface of the ferromagnetic body occurs.

The Young's modulus (compression elastic modulus) of the flexible magnetic adsorption sheet in the thickness direction is the degree of occurrence of wrinkles, bending, or the like when the flexible magnetic adsorption sheet is deformed, or the flexibility after applying a load. The reaction force when the magnetic adsorption sheet is returned to the original planar state is appropriately used as a measure of flexibility (softness) when the sheet is processed. Therefore, the flexible magnetic adsorption sheet is subjected to various bending or twisting. The Young's modulus (compression elastic modulus) in the thickness direction is an appropriate measurement method when considering the characteristics of various deformations caused by external forces.

The GOR strength (JAPAN TAPPI No. 40) is an index suitable for digitizing the toughness of paper or sheet. When printing on a photocopier or a printer, etc., a certain degree of toughness is required for the printing medium, and this is suitable for printing a measurement index of a flexible magnetic adsorption sheet for display which is excellent in suitability.

Hereinafter, each layer constituting the flexible magnetic adsorption sheet of the present invention will be described in detail.

Next layer

The adhesive used in the adhesive layer 2 of the present invention can be used as long as it does not cause peeling or breakage between the magnetic layers 3 which are next to the adhesive layer 2 when subjected to bending stress. Any adhesive. A thermoplastic resin such as a vinyl acetate resin or an emulsified paste such as an acrylic resin, a reaction-curing urethane-based adhesive, or a thermoplastic resin which has been thermally melted may be used. In particular, a polyolefin-based (co)polymer such as ethylene vinyl acetate, ethylene vinyl alcohol, polypropylene, or polyethylene can be suitably used. The method can then be subsequently joined by well-known wet lamination or dry lamination, preferably by thermal lamination of a thermoplastic resin type of adhesive, polypropylene or polyethylene as an adhesive. Further, the thickness of the layer 2 is preferably 10 to 20 μm. When it is 10 μm or less, sufficient adhesion to the magnetic layer 3 cannot be maintained, and in the case of 20 μm or more, it is uneconomical because of too much adhesive.

Magnetic layer

The magnetic layer 3 is composed of at least a strong magnetic powder and a binder which generate a magnetic force due to magnetization, and the binder acts to interconnect the ferromagnetic powder in a dispersed state and can impart flexibility to the magnetic body. The flexible end of the absorbent sheet.

Examples of the ferromagnetic powder used in the present invention include Sr ferrite powder, Ba ferrite powder, and rare earth (Sm-Co, Nd-Fe-B, Sm-Fe-N, etc.) ), iron powder, etc. Among the various ferromagnetic powders, since the Sr ferrite powder and the Ba ferrite powder are metal oxides, they are not oxidatively degraded and are less expensive than rare earths, and thus are suitable for use in flexible magnetic adsorption sheets.

As the binder for dispersing and interconnecting such ferromagnetic powders, epoxy resin, ethylene vinyl acetate copolymer, ethylene vinyl acetate block copolymer, vinyl chloride vinyl acetate copolymer, ethylene and the like are suitable. An organic high molecular weight material such as a copolymer of (meth) acrylate, an acrylic resin, a polyester resin, a polyurethane resin, or a polyester urethane resin. These may be used singly or in combination of several kinds of resins, and it is preferable to select the adhesiveness of the coating liquid, the flexibility of the magnetic layer 3, and the adhesion to the resin sheet layer 4. When the magnetic layer 3 is coated on the resin sheet layer 4 and wound up to the drum, in the case where the agglomeration of the resin sheet layer 4 and the magnetic layer 3 becomes a problem, it may be combined in consideration of balance with flexibility. Polyester polyurethane resin and ethylene chloride vinyl acetate copolymer.

Further, the weight ratio of the ferromagnetic powder to the binder which is a main component of the magnetic layer 3 is a balance between flexibility and magnetic force. The binder is preferably 8 parts by weight or more and 30 parts by weight or less, more preferably 10 parts by weight or more and 25 parts by weight or less based on 100 parts by weight of the ferromagnetic powder. When the amount of the binder is too small, the magnetic layer 3 may be broken or cracked. When the amount is too large, it tends to be difficult to obtain a sufficient adsorption force to the surface to be adsorbed.

The thickness of each of the magnetic layers 3 is preferably 30 to 60 μm in the case where the adhesive constituting the adhesive layer is polyethylene or polypropylene. In the case of 30 μm or less, it becomes difficult to obtain a sufficient adsorption force for the surface to be adsorbed, and in the case of 60 μm or more, the flexibility of the flexible magnetic adsorption sheet is impaired, and there is an increase in bending. The tendency to break or crack the risk. Further, in the case where the thickness of each of the magnetic layers 3 is a polyurethane type in which the adhesive constituting the adhesive layer is more flexible (softness), it is preferably 40 to 80 μm. When it is 40 μm or less, it becomes difficult to obtain sufficient adsorption force to the surface to be adsorbed, and when it is 80 μm or more, the flexibility of the flexible magnetic adsorption sheet is impaired, and the fracture is increased with respect to bending. Or the tendency to risk the crack.

Resin sheet

The resin sheet layer 4 of the present invention is preferably white in consideration of printability. The material may be suitably added with white pigment to polyethylene, polypropylene, polymethylpentene, polystyrene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate. Diester, polyamine, polyimine, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene/vinyl alcohol copolymer, polycarbonate, polymethyl methacrylate, polybutene - 1. A resin sheet composed of a resin such as polyetheretherketone, polyfluorene, polyether oxime, polyether sulfimine or polyphenylene sulfide, or a rubber compound such as an anthrone rubber or a nitrile rubber.

Further, the resin sheet layer 4 may have a fine void (air bubble) inside. By having fine voids, it is possible to easily combine the strength and flexibility of the resin sheet layer 4 to a high degree, and it is possible to reduce the weight of the resin sheet layer. As a sheet having fine voids, synthetic paper YUPO (manufactured by YUPO CORPORATION), TOYOPEARL SS (manufactured by Toyobo Co., Ltd.), and Pyren Film (Toyo Textile Co., Ltd.), which are foamed polypropylene sheets (foamed OPP), are preferably used. Company system), CRISPR (made by Toyobo Co., Ltd.), W-900 (made by Diafoil Hoechst Co., Ltd.), E-60 (made by Toray Industries, Inc.), etc. Among them, a polyester system represented by polyethylene terephthalate (PET) is preferred in terms of a balance between heat resistance, flexibility, and strength.

Further, as shown in Fig. 2, the resin sheet layer 4 preferably has a structure in which the film layer 42 is provided on both sides of the base material layer 41, and further has an undercoat layer 43 on both sides thereof. With such a configuration, when the base material layer 41 has a void, the smoothness of the resin sheet layer 4 can be easily maintained due to the presence of the coating layer 42. Further, the undercoat layer 43 is preferably a material having a polarity in order to secure the adhesion (wetness) of the magnetic layer 3 or the toner for electrophotography.

The base material layer 41 may have a fine void ratio of 10.0% or more and 50.0% or less based on the volume fraction of the entire resin sheet layer 4. By virtue of the fine voids, the strength and flexibility of the resin sheet layer 4 can be achieved to a high degree, and the weight of the resin sheet layer can be reduced. When the volume fraction of the fine voids is less than 10.0%, the flexibility imparting effect is lowered, and when it exceeds 50.0%, not only the strength of the resin sheet layer is weakened, but even if the coating layer 42 is present, the surface of the resin sheet layer 4 is present. The smoothness is also deteriorated, and the adhesion between the coating layer 42 and the base layer 41 tends to decrease.

As a method of forming fine voids in the inside of the base material layer 41, a polymer which is incompatible with the main raw material of the base material layer is melt-kneaded by an extruder and calendered and cooled to obtain the polymer fine particles. a method in which an island is dispersed in the main raw material, and a void caused by interfacial peeling is generated around the polymer microparticle by extending the sheet; or a method of changing the polymer into inorganic microparticles Etc., as long as the flexibility and strength of the resin sheet layer 4 can be maintained, there is no problem in forming voids by any method.

The film layer 42 sandwiching the base material layer 41 from both sides may not have fine voids, and may have a volume fraction of 1.0% or more based on the entire resin sheet layer 4 for the same reason as the base material layer 41. 15.0% or less of fine voids are not shown. If the void is 15% or less, the effect on the smoothness of the resin sheet layer 4 is small.

Measurement of void ratio

The method for measuring the volume fraction of the fine voids in the base material layer 41 and the coating layer 42 is to observe 10 sections of the cross section of the resin sheet layer 4 by an electron microscope, and to measure the fine voids occupied by the respective sections from the image data. After the area ratio Sa, Sa ^3/2 after the area ratio Sa is 3/2 power is regarded as a volume fraction (void ratio).

It is preferable to provide the undercoat layer 43 on the two outermost surfaces of the resin sheet layer 4. By providing the undercoat layer 43, the wettability or the adhesion property to the magnetic layer 3 or the toner for electrophotography can be improved. The compound constituting the undercoat layer 43 is preferably a polyester resin from the viewpoint of polarity, and is, for example, a polyurethane resin, a polyester polyurethane resin, or acrylic acid. Resin or the like can be imparted to the film layer 42, magnetic Any compound may be selected for the wettability or the binding property of the toner layer 3 and the toner for electronic photographs.

Further, in the undercoat layer 43, fine particles may be contained in order to improve the smoothness of the flexible magnetic adsorption sheet. Examples of the fine particles are titanium oxide, cerium oxide, aluminum oxide, etc., and any one may be used as long as it can be used as a printing medium without impairing whiteness. By imparting smoothness to the flexible magnetic adsorption sheet, even when a plurality of sheets are mounted on the paper feed tray at the time of printing, occurrence of double paper feeding can be suppressed.

Further, as for the undercoat layer 43 which is a printing surface, a material which is in consideration of wettability with a receiving layer of an inkjet ink, a printing ink receiving layer, a heat sensitive layer, a point impact receiving layer, or the like can be suitably applied. The undercoat layer 43 is applied as appropriate or in place of the undercoat layer 43.

Further, the thickness of the resin sheet layer 4 is preferably 40 to 80 μm. The balance of flexibility and strength of the resin sheet layer 4 can be adjusted according to the structure of the material or the void. When the thickness is less than 40 μm, the color of the magnetic layer 3 passes through the resin sheet layer 4 and is recognized. The tendency is that when it exceeds 80 μm, the flexibility is liable to lower, and the thickness of the flexible magnetic adsorption sheet becomes thick, which may cause an obstacle in the printing of the photocopier or the printer.

The flexible magnetic adsorption sheet of the present invention must have a Young's modulus in the thickness direction of 70 kgf/cm ² to 400 kgf/cm ² , a Gurley strength of 1 mN to 20 mN, and a Young's modulus of 90 kgf/cm ² ~ 200kgf/cm ² , and the intensity of Gore is 7mN~15mN. When the Young's modulus is less than 70 kgf/cm ² , the flexibility of the sheet is too high, and paper jam is likely to occur when printing on a printer or the like. When it is more than 400 kgf/cm ² , the strength tends to be too strong, and the flexibility tends to be impaired. In addition, when the strength of the mine is less than 1 mN, the flexibility tends to be too high. When the strength is higher than 20 mN, the adhesion is lowered when the adsorbed body has a curved surface or irregularities, and it is easy to be in the column. When printing, there is a problem that the paper feed from the paper cassette cannot be performed.

The flexibility and strength of each layer of the flexible magnetic adsorption sheet are not necessarily required to be similar, in consideration of the cracking/breaking of the magnetic layer 3 or the toner transfer property at the time of printing on a printer or the like. For example, the flexibility of the magnetic layer 3 and the resin sheet layer 4 may be increased first, and the strength of the flexible magnetic adsorption sheet 1 may be adjusted by the adhesive layer 2.

Next, a method of manufacturing the flexible magnetic adsorption sheet will be described by taking the flexible magnetic adsorption sheet 1 as an example.

The method for producing the flexible magnetic adsorption sheet 1 of the present invention is to first apply a magnetic coating material in which a ferromagnetic powder and a binder are dissolved and dispersed to a resin sheet layer 4, and a resin sheet layer 4 coated with a magnetic coating material. By passing through the alignment magnetic field, the easy magnetization axis of the ferromagnetic powder is aligned in the in-plane direction, and then the solvent in the magnetic coating is evaporated by a hot air dryer to form the magnetic layer 3 to be dried and solidified on the resin sheet layer 4. Laminated sheet a. Thereafter, the magnetic layer 3 faces of the laminated sheets a are adhered to each other via the adhesive layer 2, whereby the flexible magnetic adsorption sheet 1 is formed.

Modulation of magnetic coatings

For the adjustment of the magnetic coating material, a solvent for dissolving and dispersing the ferromagnetic powder and the binder is used. The solvent is not particularly limited, and for example, ketones such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, and cyclohexanone; methanol, ethanol, propanol, butanol, and the like can be used. Alcohols such as propanol; methyl acetate, ethyl acetate, propyl acetate, An ester such as butyl acetate, ethyl lactate or ethylene glycol acetate; an ether such as diethylene glycol dimethyl ether, 2-ethoxyethanol, tetrahydrofuran or dioxan; benzene, toluene, An aromatic hydrocarbon compound such as xylene; a halogenated hydrocarbon compound such as dichloromethane, dichloroethane, carbon tetrachloride, chloroform or chlorobenzene. These fluxes may be used alone or in combination of two or more. The solvent for dissolving and dispersing the ferromagnetic powder and the binder of the present invention is preferably a combination of toluene and MEK.

Further, in the magnetic paint, a dispersant may be added for the purpose of dispersing the auxiliary ferromagnetic powder and the binder.

As a dispersing and dissolving device for preparing the magnetic paint, for example, a dispersing mixer, a bead mill, a kneader, a mixer, a ball mill, a sand mill, a roll mill, an extruder, a homogenizer, an ultrasonic disperser can be used. Wait. These devices may be used alone or in combination of two or more. Regarding the present invention. As means for dissolving and dispersing the ferromagnetic powder and the binder, it is preferred to use a pulverizer in order to prevent clogging of the coating liquid causing poor dispersion when the blending is performed by the bead mill. After the pre-stirring, the present blending using a bead mill was carried out.

Coating method

As a coating method of the magnetic coating, it can be known by a bar coating method, a wire bar coating method, a lithographic coating method, a knife coating method, an air knife coating method, a gate roller coating method, a curtain coating method, a spray coating method, a die coating method, and the like. The coating method is applied.

The amount of application of the magnetic layer 3 is determined by the composition of the adhesive layer 2, and the strength, flexibility, and magnetic force balance of the flexible magnetic adsorption sheet 1 are even in the state of being coated/dried on the resin sheet layer 4, and even In order to shorten the drying time and accelerate the coating speed, it is preferred to adjust the coating amount (solid content coating amount) so that the layer thickness becomes in the range of 30 to 80 μm.

Strong magnetic powder alignment method

In order to continuously perform magnetic field alignment in the direction of the coating surface in the easy magnetization axis of the ferromagnetic powder in the coating film, the resin sheet layer 4 after the application of the magnetic layer 3 (undried state) immediately passes through the resin sheet layer. 4 The magnetic field of the magnetic flux parallel to the direction of travel may be. As an example of the means, it is made in the traveling direction of the resin sheet layer 4 by a method in a solenoid, or by causing a permanent magnet to move back and forth on both sides of the front and back sides of the resin sheet layer 4. The method of the space in which the magnetic flux occurs.

Method of laminating sheets a to each other

If the method of bringing the laminated sheets a to each other is such that the balance between the strength and the flexibility of the flexible magnetic adsorbing sheet 1 can be maintained, any method known in the art can be employed. For example, the adhesive sheet b can be obtained by uniformly applying an adhesive to the surface of the magnetic layer 3 of one of the laminated sheets a, by curing with an adhesive or overlapping with another laminated sheet a before curing. When considering the economic aspect, it is preferable to use a polypropylene or polyethylene as a thermal layer of an adhesive.

The flexibility or strength of the laminated sheet b can also be controlled by the thickness of the adhesive layer 2 or the type of the adhesive at this time.

That is, even if the laminated sheets a are the same, in the subsequent step, the flexibility or strength of the laminated sheets b can be controlled to a desired value.

Further, according to the method for producing a flexible magnetic adsorption sheet according to the present invention, the laminated sheet a is formed, and then the magnetic layer 3 of the laminated sheet a is adhered to each other to obtain a laminated sheet b, whereby the flexibility can be suppressed. The curl of the magnetic adsorption sheet. That is to say, since the laminated sheet a can be produced in successive steps, even if curl is generated, it generally becomes It is a curl toward either the resin sheet side or the magnetic layer side, and by the step of obtaining the subsequent laminated sheet b, the magnetic layers of the laminated sheet a can be mutually connected, and there is a direction in which the curl is generated, It also has the advantage that the curls cancel each other out.

Further, even if the flexibility or strength of the laminated sheet a is uneven between steps, the flexibility or strength of the flexible magnetic adsorbing sheet 1 can be unified by adjusting the thickness of the adhesive layer 2 or the like. The advantages.

Magnetization method of laminated sheet b

The laminated sheet b can be magnetized by a known method. The magnetic layer of the easy magnetization axis in the in-plane direction is applied by the multi-polar magnetization of (NS)(SN)(NS)... in the direction of the easy magnetization axis, and the vertical direction of the anti-magnetic pole surface of the SS or NN can be generated. The magnetic flux is leaked, and the magnetic adsorption force is effectively exerted between the strong magnetic walls such as steel. The magnetization conditions can be appropriately set in consideration of the type and use of the magnetic material.

It is preferable that the in-plane alignment of the easy magnetization axis of the magnetic layer has a squareness ratio of 80% or more calculated from the magnetization curve in the in-plane direction. If it is less than 80%, the residual magnetic flux density after magnetization is insufficient, and there is a possibility that sufficient magnetic adsorption force cannot be obtained.

The measurement of the square ratio can be measured by, for example, a vibration type magnetic characteristic measuring device (manufactured by Toei Industrial Co., Ltd., trade name: VSM).

[Examples]

Hereinafter, the flexible magnetic adsorption sheet of the present invention will be specifically described by way of examples and comparative examples, but the present invention is not limited to the examples.

Example 1

The method for producing the flexible magnetic adsorption sheet and the like are described below.

The components of Table 1 were added to a pulverizer, and dispersed in advance for 30 minutes, and then uniformly dispersed by a bead mill to prepare a magnetic coating for magnetic layer formation. On the other hand, in the case of the resin sheet layer, the ratio of 80% by weight of the polyethylene terephthalate resin as a raw material to 20% by weight of polystyrene is blended in a respective twin-screw extruder. The polyester composition obtained by melting the polyester composition at 280 ° C to the base material layer and blending 80 wt% of the polyethylene terephthalate resin as a raw material with 20 wt% of titanium oxide The film layer was melted at 280 ° C to both outer side surfaces of the substrate layer, and guided to a mold for extrusion. After cooling the rotating drum for adhesion curing, a longitudinal stretching of 3.5 times was performed at 100 ° C with a roll stretching machine. Then, it was subjected to a 3.5-fold extension at 125 ° C by a tenter, and heat-fixed at 220 ° C to obtain a polyester film having a film layer on both outer side faces of the substrate layer and having a large number of voids inside. Thereafter, about 2% by weight of the copolymerized polyester resin (Toyobo Co., Ltd.) Separately, VYLON MD-16) is mixed with an isocyanate-containing polyurethane resin (Erastron, manufactured by Daiichi Kogyo Co., Ltd.) into a 7/3 (by weight) mixed solution of water and isopropyl alcohol. After the bar coating method was applied, a resin sheet layer having an undercoat layer on both outer sides of the polyester film was obtained by drying at 80 ° C for 2 minutes and at 170 ° C for 30 seconds. The thickness of the resin sheet layer was 50 μm in total thickness of the undercoat layer/film layer/substrate layer/skin layer/undercoat layer. Further, the void ratios of the substrate layer and the film layer were 25% and 5%, respectively. In the resin sheet layer, a magnetic layer forming magnetic coating material is applied to one surface of the resin sheet layer by a bar coating method, and the surface is aligned in the in-plane alignment magnetic field 5000G by the same pole of the permanent magnet. After the internal alignment, drying was carried out to obtain a laminated sheet a having a magnetic layer thickness of 50 μm and a total thickness of about 100 μm.

The magnetic layers of the obtained laminated sheets a are bonded to each other by thermal lamination using polyethylene to obtain a laminated sheet b which can be printed on both sides. The thickness of the adhesive layer formed of polyethylene at this time was 13 μm.

Next, multipolar magnetization (magnetization pitch: 2.5 mm) was alternately performed so that the laminated sheet b was divided in the in-plane direction, and a flexible magnetic adsorption sheet having a total thickness of 213 μm of Example 1 was obtained. The measurement values of the Young's modulus, the Gurley strength, the curl value, the surface magnetic flux density, and the magnetic adsorption force in the thickness direction of the flexible magnetic adsorption sheet produced in the present Example 1 were measured, and the printer was printed on the printer. The paper is confirmed by the passage of time.

Example 2

A flexible magnetic adsorption sheet having a total thickness of 173 μm of Example 2 was obtained in the same manner as in Example 1 except that the layer thickness of the magnetic layer was changed to 30 μm. The measurement was made in the second embodiment The measured values of the Young's modulus, the Gurley strength, the curl value, the surface magnetic flux density, and the magnetic adsorption force in the thickness direction of the flexible magnetic adsorption sheet were confirmed for the paper passability at the time of printing by the printer.

Example 3

A flexible magnetic adsorption sheet having a total thickness of 233 μm of Example 3 was obtained in the same manner as in Example 1 except that the thickness of the layer of the magnetic layer was changed to 60 μm. The measurement values of the Young's modulus, the Gurley strength, the curl value, the surface magnetic flux density, and the magnetic adsorption force in the thickness direction of the flexible magnetic adsorption sheet produced in the third embodiment were measured, and the printer was printed on the printer. The paper is confirmed by the passage of time.

Example 4

A flexible magnetic adsorption sheet having a total thickness of 213 μm of Example 4 was obtained in the same manner as in Example 1 except that the resin sheet layer was changed to a PET film (trade name: EMBLET S50 μm manufactured by Unitika Co., Ltd.). The measurement values of the Young's modulus, the Gurley strength, the curl value, the surface magnetic flux density, and the magnetic adsorption force in the thickness direction of the flexible magnetic adsorption sheet produced in the fourth embodiment were measured, and the printer was printed on the printer. The paper is confirmed by the passage of time.

Example 5

A flexible magnetic adsorption sheet having a total thickness of 210 μm of Example 5 was obtained in the same manner as in Example 1 except that the undercoat layer was not formed on the resin sheet layer. The measured values of the Young's modulus, the Gurley strength, the curl value, the surface magnetic flux density, and the magnetic adsorption force in the thickness direction of the flexible magnetic adsorption sheet 1 produced in the fifth embodiment were measured for the printer column. The paper at the time of printing is confirmed by the passability.

Example 6

In addition to changing the layer thickness of the magnetic layer to 40 μm, the magnetic layer of the laminated sheet a was changed to a polyurethane-based adhesive (manufactured by Mitsui Chemicals, Inc., trade name: TAKELAC A-969V, hardener: Mitsui Chemicals Co., Ltd. The flexible magnetic adsorption sheet of Example 6 was obtained in the same manner as in Example 1 except that the product name: TAKENATE A-5). The layer thickness of the adhesive layer formed of the urethane-based adhesive at this time was 13 μm.

Example 7

In addition to changing the layer thickness of the magnetic layer to 80 μm, the magnetic layer of the laminated sheet a was changed to a polyurethane-based adhesive (manufactured by Mitsui Chemicals, Inc., trade name: TAKELAC A-969V, hardener: Mitsui Chemicals Co., Ltd. The flexible magnetic adsorption sheet of Example 7 was obtained in the same manner as in Example 1 except that the product name: TAKENATE A-5). The layer thickness of the adhesive layer 2 formed of the urethane-based adhesive at this time was 13 μm.

Example 8

In addition to changing the layer thickness of the magnetic layer to 90 μm, the magnetic layer of the laminated sheet a was changed to a polyurethane-based adhesive (manufactured by Mitsui Chemicals, Inc., trade name: TAKELAC A-969V, hardener: Mitsui Chemicals Co., Ltd. The flexible magnetic adsorption sheet of Example 8 was obtained in the same manner as in Example 1 except that the product name: TAKENATE A-5). The layer thickness of the adhesive layer 2 formed of the urethane-based adhesive at this time was 13 μm.

Example 9

A flexible magnetic adsorption sheet having a total thickness of 153 μm of Example 9 was obtained in the same manner as in Example 1 except that the thickness of the layer of the magnetic layer was changed to 20 μm. The measured values of Young's modulus, GRAY strength, crimp value, surface magnetic flux density, and magnetic adsorption force in the thickness direction of the flexible magnetic adsorption sheet produced in the present Example 9 were measured, and the printer was printed on the printer. The paper is confirmed by the passage of time.

Comparative example 1

The bonding of the laminated sheets a of Example 1 was carried out, and a flexible magnetic adsorption sheet having a total thickness of 100 μm of Comparative Example 1 having a printable surface on one side was obtained. The measured values of Young's modulus, GRAY strength, crimp value, surface magnetic flux density, and magnetic adsorption force in the thickness direction of the flexible magnetic adsorption sheet produced in Comparative Example 1 were measured, and the printer was printed. The paper is confirmed by the passage of time.

Comparative example 2

A flexible magnetic adsorption sheet having a total thickness of 313 μm of Comparative Example 2 was obtained in the same manner as in Example 1 except that the resin sheet layer was changed to a PET film (trade name: EMBLET S100 μm manufactured by Unitika Co., Ltd.). The measured values of Young's modulus, GRAY strength, crimp value, surface magnetic flux density, and magnetic adsorption force in the thickness direction of the flexible magnetic adsorption sheet produced in Comparative Example 2 were measured, and the printing was performed on the printer. The paper is confirmed by the passage of time.

Measurement methods

The measurement methods of each physical property and the like are described below.

Young's modulus in the thickness direction (compression elastic modulus)

The measurement of the Young's modulus in the thickness direction was performed while applying a pressure to a test piece of 2.5 cm × 2.5 cm to a maximum of 3 kgf/cm ² using a universal tensile tester in an environment of 23 ° C and 50%. The displacement amount of the thickness is curved with respect to the displacement amount L according to the following mathematical formula 1, and the Young's modulus E in the thickness direction is obtained from the slope of the straight line.

Mathematical formula 1 W=E(A/L0)logL

E: Young's modulus in the thickness direction (kgf/cm ² )

A: sample cross-sectional area (cm ² )

L: displacement (cm)

W: load (kg)

L0: initial thickness of sample (cm)

Sheet strength

The measurement of the strength (toughness) of the flexible magnetic adsorption sheet was carried out in accordance with the strength test method (Gorefa) of the weight-bearing bending of JAPAN TAPPI No. 40.

Confirmation of curl characteristics

The evaluation of the curling property is to cut the flexible magnetic adsorbing sheet into the A4 size, and after mounting to the paper feeding cassette of the full color printer LBP-9600C manufactured by CANON, the photo image is printed on the entire side, at the horizontal plane. When the four sides are placed in the upward facing manner, the shortest distance from the horizontal plane to the corner of the flexible magnetic adsorption sheet 1 is measured by the horizontal plane, and the measurement points of the number of repetitions of the measurement are compared five times. The average value is the difference (Δ: delta) between the average of the four sides of the sheet before printing, and is set to the curl value. When the evaluation reference system curl value Δ (delta) is 0.0 mm to 1.0 mm, it is set to ○, when 1.0 mm to 5.0 mm, it is set to Δ, and when it is 5.0 mm or more, it is set to ×.

Paper passing characteristics

The paper passed the evaluation criteria of the test, and the flexible magnetic adsorption sheet was cut into A4 size. After being mounted on the paper feed cassette of the full-color printer LBP-9600C manufactured by CANON, the photo image was printed on the whole side. Then, the printing is performed on the other side, and the problem is that the flexible magnetic adsorption sheet is discharged when it is discharged, and the state in which the sheet is stuck is set to Δ, and the inside of the printer is set to Δ. The situation in which a large number of pieces are stuck is set to ×.

Measurement of magnetic properties

The measurement of the surface magnetic flux density is performed by using a Tesla meter (trade name: Japanese electromagnetic detector GV-300), and the surface of the flexible magnetic adsorption sheet is measured by the probe tip at a range of about 50 mm square, and the maximum value is regarded as measurement. value.

Adsorption test

The magnetic adsorption force is evaluated by cutting the front end of the long side of the flexible magnetic adsorption sheet cut into 100×148 mm, fixing the cotton thread to the hole side, and fixing the opposite side to the Tensilon universal testing machine via the trolley. On the top, the flexible magnetic adsorption sheet 1 is attracted to a smooth iron plate placed parallel to the ground, 100 × 130 mm, and will be magnetized when it is moved at a speed of 200 m/min on a Tensilon universal testing machine. .

The Young's modulus of the flexible magnetic adsorption sheet of Example 1 was 114 kgf/cm ^{2 in the} thickness direction, and the Gurley strength was 10 mN in the longitudinal direction and 14 mN in the transverse direction, and the crimp value and the paper passage characteristics were all good. The Young's modulus of the flexible magnetic adsorption sheet of Example 2 was 100 kgf/cm ^{2 in the} thickness direction, and the Grossile strength was 8 mN in the longitudinal direction and 9 mN in the transverse direction, and the curl value and the paper passage characteristics were all good. The Young's modulus of the flexible magnetic adsorption sheet of Example 3 was 131 kgf/cm ^{2 in the} thickness direction, and the Gurley strength was 11 mN in the longitudinal direction and 16 mN in the transverse direction, and the curl value and the paper passage characteristics were all good. The flexible magnetic adsorption sheet of Example 4 has a Young's modulus in the thickness direction of 101 kgf/cm ² , and the Gore strength is 14 mN in the longitudinal direction and 14 mN in the transverse direction, and is a sheet having a slightly stronger strength, a curl value, and a paper passing property. No problem is good. The Young's modulus of the flexible magnetic adsorption sheet of Example 5 was 113 kgf/cm ^{2 in the} thickness direction, and the Gurley strength was 10 mN in the longitudinal direction and 14 mN in the transverse direction, and the curl value and the paper passage characteristics were all good. The Young's modulus of the flexible magnetic adsorption sheet of Example 6 was 110 kgf/cm ^{2 in the} thickness direction, and the Gurley strength was 9 mN in the longitudinal direction and 10 mN in the transverse direction, and the curl value and the paper passage characteristics were all good. The flexible magnetic adsorption sheet of Example 7 has a Young's modulus in the thickness direction of 135 kgf/cm ² , and the Gore strength is 14 mN in the longitudinal direction and 14 mN in the transverse direction, and is a sheet having a slightly stronger strength, a curl value, and a paper passing property. No problem is good. The flexible magnetic adsorption sheet of Example 8 has a Young's modulus of 160 kgf/cm ^{2 in the} thickness direction, a vertical strength of 16 mN and a lateral direction of 17 mN, and the sheet strength is strong, and the paper is printed on a laser printer. When passing, there is a slight paper jam. In the flexible magnetic adsorption sheet of Example 9, since the thickness of the layer of the magnetic layer is insufficient, the magnetic adsorption force is slightly insufficient, but there is no problem in practical use. Further, in the flexible magnetic adsorption sheets of Examples 1 to 9, since the magnetic layer does not face the outermost side surface, there is no fear that contamination of the magnetic layer toward the surface to be adsorbed occurs.

On the other hand, the flexible magnetic adsorption sheet of Comparative Example 1 has a Young's modulus of 69 kgf/cm ² , and the Gore strength has a longitudinal direction of 0.9 mN and a lateral direction of 0.8 mN, and the sheet strength is insufficient, and is used in a laser printer. Paper jams occur frequently when paper passes. The flexible magnetic adsorption sheet of Comparative Example 2 has a Young's modulus of 205 kgf/cm ² , and the Gore strength has a longitudinal direction of 20 mN and a lateral direction of 21 mN. The sheet strength is too strong, and the sheet of the laser printer is frequently passed. A paper jam has occurred.

Claims (8)

A flexible magnetic adsorption sheet comprising a magnetic layer on both sides of an adhesive layer, and a flexible magnetic adsorption sheet provided with a resin sheet layer on each surface of the magnetic layer opposite to the adhesive layer, characterized in that The magnetic layer includes a ferromagnetic powder and a binding agent having a Young's modulus in the thickness direction of 70 kgf/cm ² to 400 kgf/cm ² and a Gurley Intensity. ) in the range of 1mN ~ 20mN. The flexible magnetic adsorption sheet of claim 1, wherein the adhesive layer has a thickness of 10 to 20 μm, and the resin sheet has a thickness of 40 to 80 μm. The flexible magnetic adsorption sheet of claim 1, wherein the resin sheet layer is any one of polyethylene, polypropylene or polyethylene terephthalate having a void in the layer. The flexible magnetic adsorption sheet of claim 1, wherein the adhesive constituting the adhesive layer is polyethylene or polypropylene, and the magnetic layer has a thickness of 30 to 60 μm. The flexible magnetic adsorption sheet of claim 1, wherein the adhesive constituting the adhesive layer is a polyurethane having a thickness of 40 to 80 μm. The flexible magnetic adsorption sheet of claim 1, wherein the resin sheet layer is provided with an undercoat layer on both sides thereof. The flexible magnetic adsorption sheet of claim 1, wherein the magnetic layers of the sheet on which the magnetic layer has been applied are adhered to each other. A method for producing a flexible magnetic adsorption sheet, comprising the steps of: applying a magnetic coating material on one surface of the resin sheet layer, and aligning the ferromagnetic powder in the applied magnetic coating material a step of producing a layered sheet a obtained by a step of drying the solvent in the magnetic coating material to form the magnetic layer, and a step of producing a layered sheet b in which the magnetic layers of the layered sheet a are bonded to each other, and the step of forming the layered sheet b The step of magnetization on both sides.