TWI484508B - A soft magnetic material, an electronic device, an antenna module, a mobile communication terminal, a method for manufacturing a soft magnetic material, and a method for manufacturing a laminated soft magnetic sheet - Google Patents

Description

Soft magnetic material, electronic equipment, antenna module, mobile communication terminal, manufacturing method of soft magnetic material, and manufacturing method of laminated soft magnetic sheet

The present invention relates to a magnetic material which reduces the influence of nearby metals to improve the communication using a 13.56 MHz frequency of a mobile terminal having a so-called RFID (Radio Frequency Identification) function, and relates to a soft magnetic sheet of a specific gravity. And its manufacturing method. Further, it relates to a magnetic material for suppressing electromagnetic interference caused by interference of unnecessary electromagnetic waves in an electronic device.

In recent years, mobile terminals typified by mobile phones having an IC tag function for wireless communication in the 13.56 MHz domain have begun to be put into practical use. In this case, the antenna coil for transmitting and receiving is disposed in a casing of a small and thin mobile phone. However, due to electromagnetic wave isolation, the inner surface of the casing in the metal casing or the conductive treatment such as plating is close to the antenna. When the coil is present, the magnetic field lines of the magnetic field generated around the antenna coil during the transmission and reception will travel parallel to the metal surface to generate eddy currents on the metal surface, so that the magnetic field used for communication is greatly attenuated, resulting in a significant shortening of the communication distance. It has been confirmed. One of the countermeasures has been proposed in which the magnetic material is placed in parallel with the plane of the antenna coil to increase the inductance of the antenna coil and increase the communication distance (Patent Document 1).

In recent years, electronic devices such as home appliances, personal computers, mobile phones, and other mobile communication devices such as televisions have been widely used. Unwanted electromagnetic waves emitted by the above-mentioned electronic devices sometimes bring other The situation in which electronic equipment is affected by wrong actions. Therefore, in such an electronic device, a magnetic material is used to remove undesired electromagnetic waves for the purpose of suppressing electromagnetic interference.

Therefore, in the mobile communication terminal, in order to improve the communication characteristics, an antenna module in which a soft magnetic piece containing magnetic powder is disposed between the antenna coil and the spacer is used. In this case, with the miniaturization and thinning of mobile communication terminals and the like, soft magnetic sheets having a small thickness and a large magnetic permeability are expected. On the other hand, the antenna module incorporated in an electronic device such as a communication mobile terminal is contrary to the requirement of thinning the module, that is, it is required to further increase the communication distance. Therefore, in communication terminal, etc., it is required to satisfy these requirements at the same time.

In order to meet the above requirements, the size of the magnetic powder constituting the magnetic sheet used in the antenna module will be discussed. For example, by increasing the particle size of the magnetic powder used in the antenna module to increase the magnetic permeability of the magnetic sheet, the communication distance of the antenna module can be increased. however. When the particle size of the magnetic powder is increased, the power loss due to the eddy current loss of the magnetic sheet becomes remarkable, and there is a problem that the IC read voltage is lowered and the communication distance is shortened.

Therefore, in order to achieve the balance between "increasing the magnetic permeability of the magnetic sheet" and "reducing the eddy current loss", it is attempted to limit the size of the magnetic powder to be used and to reduce the magnetic properties. The amount of powder used (mixing ratio). However, in order to increase the magnetic permeability, the specific gravity of the magnetic sheet must be increased. However, if the amount of the magnetic powder used is decreased, the specific gravity of the magnetic sheet cannot be increased, which is a disadvantage. Therefore, in order to secure the necessary magnetic characteristics, it is necessary to thicken the thickness of the magnetic sheet, so that the thickness of the antenna module has to be thickened.

Therefore, a soft magnetic sheet has been proposed as a magnetic sheet for solving the above problems by mixing a flat soft magnetic powder, a chlorinated polyethylene of a binder resin, and a solvent, and applying the obtained soft magnetic coating to a release substrate. After drying, it was peeled off from the release substrate, and the flat soft magnetic powder was oriented in the in-plane direction by hot pressing at a temperature of 180 ° C and a pressure of 30 MPa (Patent Document 2).

However, in such a soft magnetic sheet, when a magnetic permeability is to be increased, if a resin having a glass transition temperature Tg much lower than room temperature is used, since the softening point of the soft magnetic sheet itself becomes low, it can be applied by one side. The heat above the softening point is compressed by a laminator or a hot press device, and the soft magnetic powder can be efficiently aligned and the specific gravity can be increased. On the other hand, for such a soft magnetic sheet, it is required to have long-term excellent dimensional stability and magnetic property stability. The reason is that if the thickness of the magnetic sheet is changed, the relative positional relationship between the antenna coil and the spacer and the magnetic characteristics of the soft magnetic sheet itself are also changed in the antenna module using the same, and the communication characteristics are changed. problem. Therefore, in the production of a soft magnetic sheet, there is an attempt to crosslink the polymer binder in combination with a hardener.

Patent Document 1: Japanese Laid-Open Patent Publication No. 2000-48152, Patent Document 2: JP-A-2002-158488

However, after the soft magnetic coating is applied to the release substrate, when the solvent is dried, the curing agent reacts with the binder resin to start the curing reaction, and if it is further heated and compressed using a laminator or a hot press, The hardening reaction proceeds more, and is directly hardened in a state in which it is contained in a state of being compressed to a certain extent, so that the specific gravity cannot be increased to a desired value. Further, when the glass transition temperature Tg of the binder resin is too low, when the soft magnetic sheet is placed in a high temperature or high temperature and high humidity environment, the compressed soft magnetic sheet is slackened and the thickness is restored, which is a problem.

The present invention has been made to solve the above problems, and an object thereof is to provide a soft magnetic material which is crosslinked in a state in which a soft magnetic powder is closely aligned in a binder resin, and a method for producing the same. The specific gravity is increased, and the dimensional change and the change in magnetic characteristics are small in a high-temperature or high-temperature high-humidity environment, and an electronic device using the magnetic material of the present invention, for example, an antenna module and a mobile communication terminal, is provided.

The inventors of the present invention have found that the above object can be attained by using a flat shape as a soft magnetic powder and a polyester resin as a binder resin and crosslinking the binder resin, and the present invention can be completed.

That is, the present invention provides a soft magnetic material comprising at least a flat soft magnetic powder dispersed in a crosslinked polyester resin.

Moreover, the present invention provides an antenna module and a mobile communication terminal including the antenna module, characterized in that the electronic device including the soft magnetic material is, for example, a soft magnetic material laminated on a support body on which an antenna coil is formed.

Furthermore, the present invention provides a method for producing a soft magnetic material for producing a sheet-like soft magnetic material, which is characterized in that at least a flat soft magnetic powder, a polyester resin, a crosslinking agent and a solvent are mixed. After the soft magnetic composition is applied onto the release substrate, it is dried at a temperature at which the crosslinking reaction does not substantially occur, and is compressed at a temperature at which the crosslinking reaction occurs. In this case, it is preferred to carry out the compression at a temperature at which the crosslinking reaction does not substantially occur before the temperature at which the crosslinking reaction is substantially carried out without drying at a temperature at which the crosslinking reaction occurs.

Moreover, the present invention also provides a method for producing a laminated soft magnetic sheet, which comprises applying a soft magnetic composition comprising at least a flat soft magnetic powder, a polyester resin, a crosslinking agent and a solvent to a release substrate. Drying and removing the release substrate at a temperature at which the crosslinking reaction does not substantially occur, and repeating the above steps to obtain at least two dried sheets of the soft magnetic composition, and at least two of the dried sheets are subjected to Laminated and compressed at the temperature at which the crosslinking reaction will occur. In this case, it is preferred to compress at a temperature at which substantially no crosslinking reaction occurs after the at least two dried sheets are laminated and before the temperature at which the crosslinking reaction occurs.

In the soft magnetic material of the present invention, the flat soft magnetic powder is a polyester resin which is closely aligned and dispersed in a binder resin, and since the polyester resin is crosslinked in this state, the ratio is large and exhibits good Magnetic properties. Moreover, even in a high-temperature environment or a high-temperature and high-humidity environment, the dimensional change is small, and it is a highly reliable soft magnetic material. Further, when a polyester resin containing phosphorus is used as the polyester resin, the acid value can be increased to exhibit excellent adhesion to the metal, so that the specific gravity can be increased. Therefore, since the soft magnetic material of the present invention has a small dimensional change after environmental testing and a small change in magnetic characteristics, it is possible to increase the communication distance by using it in a sheet form for use in an antenna module. Further, it is also possible to reduce the thickness and weight of the antenna module. Furthermore, even if such an antenna module is housed in a metal case, deterioration of communication performance can be suppressed, and the initial communication distance can be maintained. Therefore, the soft magnetic material of the present invention can be applied to an RFID application and as a radio wave absorber, and a noise electromagnetic wave absorber which is an electronic device such as a digital camera for action can be used.

The soft magnetic material of the present invention is preferably composed of at least a flat soft magnetic powder dispersed in a crosslinked polyester resin, and is preferably a sheet-shaped soft magnetic material.

In the soft magnetic material of the present invention, first, a flat soft magnetic powder is used as the soft magnetic powder. Therefore, high magnetic permeability and large specific gravity can be achieved by arranging the flat soft magnetic material in the two-dimensional in-plane direction.

The raw material of the flat soft magnetic powder may be any soft magnetic alloy such as magnetic stainless steel (Fe-Cr-Al-Si alloy), sendust alloy (Fe-Si-Al alloy), high magnetic alloy ( Permalloy), beryllium copper (Fe-Cu-Si alloy), Fe-Si alloy, Fe-Si-B (-Cu-Nb) alloy, Fe-Si-Cr-Si alloy, Fe-Si -Cr alloy, Fe-Si-Al-Ni-Cr alloy, ferrite iron, and the like. Among these, it is preferable to use Fe-Si-Al alloy or Fe-Si-Cr-Ni alloy in terms of magnetic properties.

Preferably, the soft magnetic alloys have a larger value of the real part (permeability) μ' of the composite relative magnetic permeability (preferably more than 35), and an imaginary part (magnetic loss) μ of the composite relative magnetic permeability. The value of the value is small (preferably 1 or less), and the Q value is large (more preferably 28 or more). That is, the larger the value of μ', the easier the magnetic flux of the RFID communication antenna coil passes through the corresponding antenna coil. The sensitivity can be increased, and the smaller the value of the imaginary part μ", the power loss due to the eddy current loss of the magnetic material is reduced, so that the IC call voltage is not lowered, and the communication distance is not shortened. Further, the larger the Q value, the higher the selectivity of the resonance frequency, and the sensitivity can be improved. Further, although the values of μ' and μ" vary depending on the composition and frequency of use of the magnetic alloy, the magnetic permeability μ' of the soft magnetic material of the present invention is preferably 35 or more. The magnetic permeability μ' is preferably 35 or more. The communication distance of the portable electronic device is 110 mm or more, which improves the convenience. Moreover, the specific gravity of the soft magnetic material is preferably 3.0 or more, and more preferably 3.20 or more. By increasing the soft magnetic material. The specific gravity can reduce the air contained in the soft magnetic material and improve the flame retardancy.

Further, since the flat soft magnetic alloy reduces the value of μ" in order to reduce the eddy current loss, it is preferable to use a larger electric resistance. In this case, the electric resistance can be increased by changing the composition of the magnetic alloy. For example, in Fe-Si In the case of a -Cr alloy, the ratio of Si is preferably 9 to 15% by weight.

The flat soft magnetic powder used in the present invention is a flat soft magnetic powder having an average particle diameter of 3.5 to 90 μm and an average thickness of 0.3 to 2.1 μm, and an average particle diameter of 10 to 10. 50 μ m and an average thickness of 0.5 to 1.5 μm are more preferred. Therefore, the flattening ratio is preferably set to 8 to 24, and more preferably set to 15 to 22. Further, in order to make the size of the flat soft magnetic powder uniform, it is possible to classify using a sieve or the like as necessary. Further, in order to increase the magnetic permeability of the soft magnetic material, it is effective to increase the particle size of the flat soft magnetic powder to narrow the interval between the particles, and to increase the aspect ratio of the flat soft magnetic powder to lower the soft magnetic sheet. The effect of diamagnetic fields.

The tap density (JIS K 5101) and the specific surface area (BET method) of the flat soft magnetic powder used in the present invention are inversely proportional to each other, but if the specific surface area is larger, not only the μ' value becomes large. Therefore, the μ value which does not wish to become large tends to become larger, so the numerical range thereof is set to a preferred range. Specifically, the tapping degree is preferably set at 0.55 to 1.45 g/ml to set More preferably, it is 0.65 to 1.0 g/ml. On the other hand, the specific surface area is preferably set to 0.40 to 1.20 m ² /g, and more preferably set to 0.65 to 1.00 m ² /g.

Further, as the flat soft magnetic powder, those whose surface is covered with an insulating layer can be used. By using the flat soft magnetic powder coated with the insulating layer, the μ' of the flat soft magnetic material is lowered, and Q is increased, so that the communication distance of the mobile terminal having the RFID (Radio Frequency Identification) function can be improved. The method for forming the insulating layer includes a method of coating with a resin, a method of forming an oxide film by heating, and a method of forming an oxide film by a thin film forming technique such as sputtering of a soft magnetic powder. As the oxide film, Al ₂ O ₃ , SiO ₂ or the like can be used. The resin to be coated may be a resin such as an acrylate type, an ester type, an urethane type or an epoxy type.

The flat soft magnetic powder used in the present invention does not necessarily have to use a flat soft magnetic powder coated with an insulating layer, but it is preferable that at least about 5% by weight of the flat soft magnetic powder used is a flat soft magnetic layer coated with an insulating layer. powder.

Further, in the present invention, the soft magnetic powder may be a soft magnetic powder obtained by coupling treatment with a coupling agent such as a decane coupling agent. By using the soft magnetic powder that has been subjected to the coupling treatment, the reinforcing effect of the interface between the flat soft magnetic powder and the polyester resin (bonding resin) can be enhanced, and the specific gravity can be improved and the corrosion resistance can be improved. As the coupling agent, for example, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyl propyl, or γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane Gamma-glycidoxypropylmethyldiethoxysilane or the like. Further, the coupling treatment may be performed by previously applying the soft magnetic powder, or by mixing the flat soft magnetic powder and the binder resin while performing the above-described coupling treatment.

When the amount of the flat soft magnetic powder in the soft magnetic material of the present invention is too small, the desired magnetic properties cannot be obtained. If the amount is too large, the amount of the resin is reduced to deteriorate the formability, so that 400~ It is preferably 600% by weight, more preferably 450 to 550% by weight.

In the binder resin of the present invention, a polyester resin which has good processability, low hygroscopicity, can maintain practical strength after being flaky, and can hold a large amount of flat soft magnetic powder can be used. If the number average molecular weight of such a polyester-based resin is too small, the mechanical strength of the obtained sheet-like soft magnetic material may become insufficient, and if it is too large, the obtained sheet-like soft magnetic material may become hard and brittle. Therefore, it is better to use 3000~100000, preferably 8000~50000, especially 10000~50000.

Further, if the glass transition temperature of the polyester resin of the binder resin is too low, the modulus of elasticity at a high temperature is lowered, and the bonding strength between the soft magnetic powders is insufficient, and if it is too high, the obtained sheet-like soft magnetic material is changed. It is hard, and the workability at room temperature is deteriorated, and the softening point tends to become too high, so that the compression of the soft magnetic material and the alignment of the soft magnetic powder cannot be smoothly performed, so the glass transition temperature is - 20 to 40 ° C is preferred, preferably -20 to 10 ° C, and the softening point is preferably 130 ° C or less, preferably 100 ° C or less.

If the hydroxyl value (JIS K 1557) of the polyester resin of the binder resin is too low, the crosslinking may not be sufficiently caused to cause insufficient mechanical strength, and the thickness of the soft magnetic material may become large; if it is too high, it may be sucked. The wetness is too high, so it is preferably 4.5 mgKOH/g to 15 mgKOH/g, more preferably 4.5 mgKOH/g to 8 mgKOH/g.

When the acid value (titration method) of the polyester resin of the binder resin is too low, the adhesion between the magnetic powder and the resin is deteriorated, and if it is too high, the resin property is lowered, so that it is 2.0 mgKOH/g to 4.0 mgKOH/ g is preferably more preferably 2 mgKOH/g to 3 mgKOH/g.

In the present invention, when flame retardancy is to be imparted to the soft magnetic material, a flame retardant polyester resin may be used, and the flame retardant polyester resin is preferably a polyester resin containing phosphorus. The phosphorus-containing polyester resin is a non-halogen flame retardant having a phosphoric acid residue in the molecule and exhibits high flame retardancy (UL94 V-0). Further, unlike conventional flame retardants, a large amount of flame retardant is added, and the magnetic permeability after environmental testing is also reduced.

The phosphorus-containing polyester resin may be, for example, a phosphorus-modified polyester copolymer. The phosphorus-modified polyester copolymer is obtained by introducing a phosphorus component into a main skeleton of a polyester copolymer, and copolymerizing a polyester component and a phosphorus component. Here, the polyester component can be used: a polymer compound formed of ethylene glycol and terephthalic acid, naphthalenecarboxylic acid, adipic acid, sebacic acid or isophthalic acid; or 1,4-butanediol a polymer compound formed with terephthalic acid, adipic acid or sebacic acid; or a polymer compound formed of 1,6-hexanediol and adipic acid, sebacic acid or isophthalic acid. Further, as the phosphorus component, a phosphonate type polyol, a phosphate type polyol, a vinyl phosphonate, an allyl phosphonate or the like can be used. The polyester copolymer in which the phosphorus component is introduced into the main skeleton in the above manner exhibits a higher flame retardancy than the case where the phosphorus component is mixed and dispersed in the polyester.

The phosphorus content of the phosphorus-containing polyester resin can satisfy the predetermined flame retardancy depending on the type of the main skeleton of the polyester resin, the type of the phosphorus component (phosphoric acid residue), and the type of other components constituting the soft magnetic sheet. It is determined by the nature that if it is too small, sufficient flame retardancy cannot be achieved, and if too much, the physical properties of the resin are lowered, so it is preferably 3.0 to 10% by weight, more preferably 3 to 6% by weight.

In the present invention, in the range which does not impair the effects of the present invention, an epoxy resin, a polyester resin, an acrylate resin, an aliphatic hydrocarbon resin, a rosin resin, a nylon may be used in combination with the above polyester resin. (nylon) resin, phenol resin, polyurethane resin, melamine resin, polyamine resin, urea formaldehyde resin, polyisocyanate or a mixture of an epoxy compound and an isocyanate compound or an imidazole compound, etc. as a binder resin.

In the soft magnetic material of the present invention, as described above, the polyester resin is crosslinked. This crosslinking can be achieved by mixing a crosslinking agent when dispersing a soft magnetic powder in a polyester resin, and causing a crosslinking reaction between the polyester resin and the crosslinking agent. As the crosslinking agent, a crosslinking agent conventionally used for the crosslinking reaction of the polyester resin can be used, and in particular, a blocked isocyanate is preferably used as the crosslinking agent. Here, "blocking isocyanate" means that an isocyanate group (-NCO) is blocked by addition of an isocyanate compound as a blocking agent, and since the blocked isocyanate does not dissociate at room temperature, the polyester resin does not crosslink. When heated to a temperature higher than the dissociation temperature of the blocked isocyanate, the blocking agent is dissociated, and the polyester resin is crosslinked by the activated isocyanate compound. The dissociation temperature of the blocking agent can be selected in the range of 80 ° C to 180 ° C. Further, specific examples of the blocked isocyanate include "Colenet 2507" (manufactured by Nippon Polyurethane Co., Ltd.).

Here, the reason why the blocked isocyanate is used is that when a soft magnetic material is produced by a general film forming technique, if an unblocked isocyanate is used as a crosslinking agent, the polyester resin and the isocyanate are dried in a solvent. In contrast, when a blocked isocyanate is used, it is not heated to a temperature at which the blocking group is removed, and the reaction does not proceed. Further, since the dry air of the solvent enters the soft magnetic material, the reaction between the polyester resin and the isocyanate is not performed below the blocking agent release temperature, and the sealing base is gradually removed after the separation, so that the soft magnetic material can be sufficiently The ground compression removes the air, and the crosslinking reaction is carried out in a state where the soft magnetic powder is closely aligned. Further, the mechanical strength of the soft magnetic material can be improved by crosslinking, and the occurrence of slack can be suppressed even in a high-temperature environment or a high-temperature and high-humidity environment, and the thickness variation can be suppressed. Further, by using a blocked isocyanate as a crosslinking agent, since the crosslinking reaction does not start above the dissociation temperature, the crosslinking is not sufficiently started, so that the soft magnetic powder is closely aligned at a temperature at which the crosslinking reaction is not started, and then dissociated. Further, the temperature is further compressed to align it, whereby a sheet-like soft magnetic material having a large specific gravity can be obtained.

In the present invention, when the blocking isocyanate has a too low dissociation temperature, cross-linking starts at a stage where the compression of the soft magnetic coating material at the time of soft magnetic material production is not sufficiently performed, and it is difficult to sufficiently control the specific gravity and the magnetic permeability. Further, in the soft magnetic coating, the drying of the solvent to be described later may be difficult, and if the dissociation temperature is too high, thermal damage will be caused to the peeling substrate used in the production of the soft magnetic material described later. °C~180°C is preferred, and 120°C~160°C is preferred. Further, since the reaction of crosslinking the polyester resin proceeds very slowly even at room temperature, the polyester resin is completely dispensed after being left at room temperature for a long time after being heated to the dissociation temperature. Combined and hardened.

If the proportion of the blocked isocyanate used is too small, the crosslinking of the polyester resin may be insufficient, and the thickness may be excessively changed. If the amount is too large, the specific gravity of the sheet will not become large, so the polyester resin is preferably 0.5. The mass % to 10% by mass, more preferably 1% by mass to 8% by mass.

The crosslinked polyester resin constituting the soft magnetic material of the present invention is a crosslinked polyester-based resin which is crosslinked by a crosslinking agent, and if the content of the soft magnetic material is too small, the specific gravity of the sheet is not If it is too much, μ' will not increase, so it is preferably 60 to 150% by weight, and more preferably 80 to 120% by weight.

In order to ensure sufficient flame retardancy such as V-1 of UL94, the soft magnetic material of the present invention may be added with other resistance without affecting heat resistance, deterioration of physical properties, hydrolysis property under high temperature conditions, surface properties, and the like. Burning agent.

Further, in the soft magnetic material of the present invention described above, a polyester resin having a low glass transition temperature Tg is used as the binder resin, and a blocked isocyanate having a dissociation temperature higher than the glass transition temperature is used as a crosslinking agent, so that softness is produced. In the case of a magnetic material, when the flat soft magnetic powder is aligned in the same plane so as not to exceed the dissociation temperature of the blocked isocyanate, the specific gravity and the magnetic permeability can be increased. In addition, when heated to a temperature higher than the dissociation temperature of the blocked isocyanate, the polyester resin is crosslinked, so that it is not in a high-temperature or high-temperature high-humidity environment as compared with a conventional magnetic sheet in which the polyester resin is not crosslinked. Slack occurs, and dimensional changes such as thickness are small. Specifically, the soft magnetic material of the present invention can be changed to a size of 3% or less after being placed in a high temperature environment of 60 ° C to 95 ° C. Moreover, the dimensional change after being placed at a temperature of 40 ° C to 90 ° C and a relative humidity of 65 to 95% under high temperature and high humidity may be 3% or less. Therefore, when a magnetic sheet used in an electronic device such as a mobile phone or a digital camera is normally used in a temperature range of -25 to 85 ° C and a high temperature and high humidity condition is 60 ° C or 96 Rh %, the present invention contributes to reduction in comparison with such evaluation. The problem of dimensional changes that occur on the high temperature side. Further, in the soft magnetic material of the present invention, since the polyester resin is in a crosslinked state, the material itself has high mechanical strength, and therefore, even if a physical impact such as a thermal change or a desired shape is applied, The strength of the powder from the end face of the soft magnetic material.

The soft magnetic material of the present invention can be compressed by subjecting a soft magnetic composition (prepared by mixing at least a flat soft magnetic powder, a polyester resin and a crosslinking agent according to a usual method) at a temperature at which a crosslinking reaction occurs. Manufacturing. Here, if the compression is carried out at a temperature at which the crosslinking reaction occurs, the crosslinking reaction is started while the crosslinking reaction is not sufficiently performed, and the flat soft magnetic powder is aligned perpendicularly to the compression direction. Since the surface is in the in-plane direction, the specific gravity is increased and good magnetic properties are obtained. In addition, when the crosslinking reaction is carried out, the entire polyester resin is crosslinked to suppress shrinkage, and dimensional stability can be improved.

However, when the soft magnetic composition is prepared, it is difficult to maintain the shape of the flat soft magnetic powder if the shear force is excessively applied to the composition, and since the flat soft magnetic powder must be aligned in a specific in-plane direction, soft magnetic properties are improved. The fluidity of the composition is preferably set at a lower viscosity. Further, it is required to form a sheet of soft magnetic material. In this case, in order to form a sheet by a coating method, it is necessary to reduce the viscosity of the soft magnetic composition. Therefore, in the soft magnetic composition, a solvent for dissolving the polyester resin as the binder resin is preferably used in combination. . As such a solvent, for example, an aromatic hydrocarbon compound such as methyl ethyl ketone, benzene, toluene or xylene, or a ketone compound such as cyclohexanone or methyl isobutyl ketone can be used. However, if the viscosity of the soft magnetic composition is too small, the specific gravity of the sheet-like soft magnetic material tends to be too small; if it is too large, coating may be difficult, and there is a problem that coating streaks may occur. Therefore, the amount of the solvent to be used is preferably such that the solid content in the soft magnetic composition is 50 to 70% by weight.

The soft magnetic material of the sheet shape can be applied to the release substrate by applying a soft magnetic composition composed of at least a flat soft magnetic powder, a polyester resin, a crosslinking agent and a solvent, and substantially no crosslinking occurs. Drying is carried out at the temperature of the reaction, and compression is carried out at a temperature at which the crosslinking reaction occurs.

First, at least a flat soft magnetic powder, a polyester resin, a crosslinking agent, and a solvent are mixed to prepare a soft magnetic composition. Specifically, the polyester resin may be dissolved in a solvent, and then the soft magnetic powder and the crosslinking agent may be added to the solution.

Then, the soft magnetic composition is applied onto the release substrate. The coating method can be a general coating method such as a coater or a doctor blade method. At this time, the coating thickness of the formed soft magnetic composition can be adjusted to a desired thickness by the aforementioned coating method. Further, at the time of application, by applying a magnetic field to the applied soft magnetic composition, the flat soft magnetic powder can be aligned in the coating in-plane direction, and the soft magnetic powder can be filled at a high density. Further, extrusion work can also be performed to increase the specific gravity.

Here, the release substrate may, for example, be polyethylene terephthalate, polyethylene naphthalate polyimide, polyphenylene sulfide, or polypropylene oxide. , polyethylene, polypropylene, polyamide, etc. The thickness of such substrates can generally range from a few μm to hundreds of μm. Further, a known release agent may be applied to the coated surface of the soft magnetic composition of the release substrate.

Then, the soft magnetic composition applied to the release substrate is dried at a temperature at which the crosslinking reaction does not substantially occur. The reason is that if the drying is performed at a temperature at which the crosslinking reaction occurs, the flat soft magnetic powder cannot be aligned in the same in-plane direction, and the desired magnetic properties cannot be obtained. Here, the term "substantially does not occur" in the temperature at which the crosslinking reaction does not substantially occur refers to a crosslinking reaction in which the flat soft magnetic powder is aligned in the same in-plane direction by a laminator or a hot press device. To be permissible. Specifically, when a blocked isocyanate is used as a crosslinking agent, "the temperature at which the crosslinking reaction does not substantially occur" means a temperature that does not reach the dissociation temperature of the blocked isocyanate. On the other hand, the "temperature at which the crosslinking reaction occurs" means the temperature above the dissociation temperature of the blocked isocyanate.

Then, the dried sheet of the soft magnetic composition is compressed at a temperature at which a crosslinking reaction occurs. In this case, the flat soft magnetic powder is aligned in the same in-plane direction, and finally the crosslinking reaction is completed. Even if it is heated at the temperature at which the crosslinking reaction occurs, the crosslinking reaction is not completed in an instant, and it takes a certain time until the crosslinking reaction ends.

Further, it may be compressed at a temperature at which the cross-linking reaction does not substantially occur after drying at a temperature at which the cross-linking reaction does not substantially occur, and before the temperature at which the cross-linking reaction occurs. In this case, when the compression is carried out at the temperature at which the crosslinking reaction occurs, since the flat soft magnetic powder has been aligned in the same in-plane direction, it is mainly that only the crosslinking reaction occurs.

Next, a method of laminating a sheet-shaped soft magnetic material will be schematically explained.

First, a soft magnetic composition comprising at least a flat soft magnetic powder, a polyester resin, and a crosslinking agent is applied onto a release substrate, and then dried at a temperature at which crosslinking reaction does not substantially occur, and then the release is performed. The substrate is subjected to this operation to obtain at least two dried sheets of the soft magnetic composition.

Then, at least two dried sheets are laminated, and compression is performed at a temperature at which a crosslinking reaction occurs. At this time, the flat soft magnetic powder is aligned in the same in-plane direction, and finally the crosslinking reaction is completed. Further, when at least two of the dried sheets are laminated and then compressed at a temperature at which the crosslinking reaction does not occur at a temperature at which the crosslinking reaction occurs, the compression is performed at a temperature at which the crosslinking reaction occurs. At this time, the flat soft magnetic powder has been aligned in the same in-plane direction, so that only the crosslinking reaction occurs.

The soft magnetic material of the present invention can be applied to a magnetic flux convergent object such as a non-contact IC card or an RFID tag or the like, or a general electromagnetic wave absorber. That is, it is applicable to a noise electromagnetic wave absorber which is an electronic device such as a flexible shielding material for RFID and a portable digital camera.

Specifically, the soft magnetic material of the present invention is preferably applicable to an antenna module for contactless data communication. The antenna module is constructed by using a double-sided tape on a substrate of a base substrate (support), a sheet-like soft magnetic material, and another area of a metal separator, and then forming a copper or aluminum on the soft magnetic material. An antenna coil composed of a metal pattern. The antenna coil is used to communicate with the antenna portion of the external reader/writer (reader writter) in order to function as a non-contact IC tag. Further, the antenna coil is connected to the signal processing circuit unit. The signal processing circuit unit is composed of a signal processing circuit necessary for non-contact data communication, an IC chip for accommodating information, and an electronic component such as a tuning capacitor, and may be disposed inside the antenna coil or may be disposed outside. Moreover, it is connected to the printed circuit board of the mobile communication terminal through the external connection portion attached to the base substrate. Here, the base substrate may be an insulating flexible substrate mainly composed of a plastic film such as polyimide, polyethylene terephthalate or polyethylene naphthalate, or may be a glass epoxy substrate or the like. The rigid substrate. Moreover, the metal isolating plate is used for the coarse call of the resonant frequency of the antenna module, and is set in a state assembled in the mobile communication terminal so as not to cause a large change in the resonant frequency of the antenna module. Such a metal separator may be a stainless steel plate, a copper plate, an aluminum plate or the like.

When the mobile communication terminal such as a mobile phone having an antenna module performs read/write and data communication, the antenna module must be close to the antenna portion of the read/write mechanism. In this way, when an electromagnetic wave or a high-frequency magnetic field transmitted from the antenna portion of the read/write mechanism passes through the antenna coil of the antenna module, an induced current corresponding to the intensity of the electromagnetic wave or the high-frequency magnetic field is generated. The induced current is rectified at the signal processing circuit portion into a read voltage of information recorded on the IC chip. The read information is modulated in the signal processing circuit unit and transmitted to the antenna portion of the read/write mechanism through the antenna coil.

(Example)

Next, the specific implementation of the soft magnetic sheet to which the present invention is applied will be described based on the experimental results.

(Examples 1A to 4A)

The mixed components shown in Table 1 were uniformly mixed by a planetary mixer or a dissolver, whereby a soft magnetic paint was prepared. In these coatings, the binder resin is a polyester resin containing phosphorus having a hydroxyl value of 6.0 KOHmg/g, a number average molecular weight of 24,000, a glass transition temperature of 4 ° C, and a phosphorus content of 3.9 wt% (Bylon 537, Toyobo Co., Ltd. system). Further, as the crosslinking agent, a blocked isocyanate (manufactured by Nippon Polyurethane Co., Ltd., trade name Kolenet 2507) was used. Further, the soft magnetic powder was coated with Fe-Si-Cr-Ni powder (JEMCO), Fe-Si-Al powder (manufactured by Dite Co., Ltd.), and SiO2 coated with Fe-Si-Cr-Ni powder (manufactured by JEMCO Co., Ltd.). The powder is formed into a powder of 5 to 10 nm thick SiO ₂ film by a vibration sputtering device or the acrylate resin is coated with Fe-Si-Cr-Ni powder (the surface of the powder made by JEMCO Co., Ltd. is treated with a decane coupling agent, and 0.01 is used. ~0.1 μm thick acrylic resin coated powder).

The obtained soft magnetic coating material was applied to a one-side peeling polyester phthalate film (peeling PET film) which was subjected to a release treatment by a roll coater so that the solid content of the coating material was 180 g/m 2 (Teijin) The company was dried at 115 ° C to obtain an uncured soft magnetic sheet supported by a peeled PET film.

Then, five sheets of the uncured soft magnetic sheet from which the PET film was removed were laminated, and the rolls were placed between the rolls and the rolls (the temperature of the upper and lower rolls was set to 150 ° C, the line load was set to 13.4 kgf/cm, and the line speed was set to 0.5 m/min) was compressed by 20 times, and it was cross-linked and hardened while aligning, and the soft magnetic sheet was obtained.

In Comparative Example 1A, except that a polyester resin having a glass transition temperature Tg of room temperature or higher (35 ° C) and a low hydroxyl value (manufactured by Unijica, trade name UE3500, hydroxyl value = 4) was used as a binder, The same operation as in Example 1A was carried out, whereby a crosslinked hardened soft magnetic sheet was obtained.

In Comparative Example 2A, the blocked isocyanate was not added with a crosslinking agent, and the same procedure as in Example 1A was carried out to prepare a crosslinked and cured magnetic sheet.

Thickness, magnetic properties (magnetic permeability μ', magnetic loss μ", coefficient of performance Q), specific gravity of the obtained cross-linked hardened soft magnetic sheet (Examples 1A to 4A and Comparative Examples 1A to 2A) And measuring the communication distance, and measuring the thickness and magnetic properties (μ', μ", Q) of the soft magnetic sheet after 96 hours in a high temperature and high humidity environment maintained at 85 ° C and 85% Rh, and further The thickness change rate, the specific gravity change rate, and the μ' change rate of the soft magnetic sheet before and after the environmental test described above. Further, the communication distance is such that the soft magnetic sheet produced is placed between the antenna device and the spacer on the mobile phone, and the communication distance at this time is measured. The effective magnetic permeability μ' is obtained by making a ring-shaped sample having a diameter of 7 mm, winding the wire coil 5 times, and measuring the AC permeability at a carrier frequency (13.56 MHz) using an impedance analyzer to obtain a ring-shaped sample. . The results are shown in Table 2.

Further, the determination of the magnetic characteristics was carried out based on the following criteria using the magnetic permeability μ' as an index.

(When Fe-Si-Cr is used as the soft magnetic powder) ◎: 42 ≦μ' ○: 38 ≦ μ' < 42 Δ: 34 ≦ μ' < 38 ×: μ' < 34

(When Fe-Si-Al is used as the soft magnetic powder) ◎: 65 ≦μ' ○: 60 ≦ μ' < 65 Δ: 55 ≦ μ' < 60 ×: μ' < 55

(When SiO _{2 is} coated with Fe-Si-Cr as a soft magnetic powder) ◎: 42≦μ'○: 38≦μ'<42Δ: 34≦μ'<38×: μ'<34

(When Fe-Si-Cr is coated with an acrylate resin as a soft magnetic powder) ◎: 42≦μ'○: 38≦μ'<42Δ: 34≦μ'<38×:μ'<34

Further, the evaluation of the specific gravity change rate, the μ' change rate, and the sheet thickness change rate was carried out in accordance with the following criteria.

(specific gravity change rate) ◎: less than 1% ○: 1% or more, less than 3% △: 3% or more, less than 5% ×: 5% or more

(μ, rate of change) ◎: less than 1% ○: 1% or more, less than 3% Δ: 3% or more, less than 5% ×: 5% or more

(change rate of sheet thickness) ◎: less than 1% ○: 1% or more, less than 3% △: 3% or more, less than 5% ×: 5% or more

As is apparent from Table 2, in Examples 1A to 4A, a soft magnetic sheet having a small dimensional change and a small change in magnetic properties even in a high-temperature and high-humidity environment can be obtained. For example, in Comparative Example 2A, in comparison with the respective examples, it is understood that the thickness change rate of the soft magnetic sheet in the examples is small, and in comparison with Comparative Example 1, the magnetic properties of the soft magnetic sheets of the respective examples after the environmental test are performed. The reduction in characteristics is also small.

Example 1B According to the mixing (parts by weight) shown in Table 3, a phosphorus-containing polyester resin (Bylon 537, manufactured by Toyobo Co., Ltd.) and a flat soft magnetic powder (Fe-Si-Cr-Ni, manufactured by JEMCO Co., Ltd.) ), a decane coupling agent (SH6040, Dongling Dow Corning Company), isopropyl alcohol (IPA) and a blocked isocyanate (Colenet 2507, Japan Polyurethane Co., Ltd.) were mixed to prepare a soft magnetic coating, and the soft magnetic coating was coated with a roller. The cloth machine was applied to a release PET film (Teijin) so that the solid content of the coating was 180 g/m ² , and dried at 115 ° C for 10 minutes to obtain an uncured soft magnetic sheet supported by the peeled PET film.

Then, five sheets of the uncured soft magnetic sheet from which the PET film was removed were laminated, and the rolls were placed between the rolls of the laminator (the temperature of the upper and lower rolls was set to 110 ° C, the line load was 3.3 kgf/cm, and the line speed was 0.5 m/min. The soft magnetic powder in the uncured soft magnetic sheet was aligned by compressing 10 times, and compressed at 150 ° C for 10 minutes under a pressure of 5 kg/cm ² to thereby crosslink and harden. Soft magnetic sheet. The soft magnetic sheet produced has a large specific ratio, and the magnetic property is reduced even when placed in a high temperature, high temperature and high humidity environment.

In Example 2B, except that the compression using a laminator was not carried out, the operation of Example 1B was repeated, whereby a cross-linked hardened soft magnetic sheet was obtained. The soft magnetic sheet produced has a large specific ratio, and the magnetic properties are reduced even under high temperature, high temperature and high humidity environments.

In Example 3B, except that the drying temperature of the soft magnetic coating applied to the peeled PET film was set to 125 ° C, the same operation as in Example 1B was repeated to obtain a crosslinked-hardened soft magnetic sheet. The soft magnetic sheet produced has a partial cross-linking of the blocked isocyanate when the soft magnetic coating is dried at 125 ° C, so the value of μ' and specific gravity is slightly smaller than that of the case of Example 1B, but it is practical. There is no problem with the value.

In Comparative Example 1B, a crosslinked hardened soft magnetic sheet was produced by repeating the same operation as in Example 1B except that an isocyanate (Colenet HL, manufactured by Nippon Polyurethane Co., Ltd.) was used instead of the blocked isocyanate. In the obtained soft magnetic sheet, since the unblocked isocyanate was used, the isocyanate was crosslinked with the phosphorus-containing polyester resin in the drying step, and the specific gravity was not increased.

Comparative Example 2B was subjected to the same operation as in Example 1B except that the blocked isocyanate was not used and the drying temperature of the soft magnetic coating was set to 120 ° C, whereby an uncured soft magnetic sheet was obtained. Then, five sheets of the uncured soft magnetic sheet from which the PET film was removed were laminated, and the laminate was not compressed by a laminator, and the mixture was compressed at 150 ° C and a pressure of 5 kg/cm ² for 10 minutes to be cross-linked and cured to obtain a soft magnetic sheet. Since the obtained soft magnetic sheet is not crosslinked, the specific gravity and magnetic properties after the environmental test are lowered.

The magnetic properties (magnetic permeability μ', magnetic loss μ), coefficient of performance Q), and specific gravity of the obtained cross-linked hardened soft magnetic sheets (Examples 1B to 3B and Comparative Examples 1B to 2B) were measured. The magnetic properties (μ', μ", Q) of the soft magnetic sheet after 192 hours in a high-temperature and high-humidity environment at 60 ° C and 95% Rh were maintained, and the change in specific gravity of the soft magnetic sheet before and after the aforementioned environmental test was further determined. The rate and the μ' rate of change were evaluated in the same manner as in the case of Example 1A. The results are shown in Table 3.

Further, the determination of the magnetic properties was carried out based on the following criteria using the magnetic permeability μ' as an index.

(Using Fe-Si-Cr as a soft magnetic powder) ◎: 42 ≦μ' ○: 38 ≦ μ' < 42 Δ: 34 ≦ μ' < 38 ×: μ' < 34

Example 4B, a mixture of phosphorus-containing polyester resin (Bylon 537, manufactured by Toyobo Co., Ltd.) and a flat soft magnetic powder (Fe-Si-Al, manufactured by Hite Co., Ltd.) were mixed according to the mixing (parts by weight) shown in Table 4. ), decane coupling agent (SH6040, Dongling Dow Corning Company), isopropyl alcohol (IPA) and blocked isocyanate (Colenet 2507, Japan Polyurethane Co., Ltd.) to prepare soft magnetic coating, the soft magnetic coating roller coating machine The coating solid content was 180 g/m ² and applied to a release PET film (Teijin Co., Ltd.), and dried at 115 ° C for 10 minutes to obtain an uncured soft magnetic sheet supported by a release PET film.

Then, five sheets of the uncured soft magnetic sheet from which the PET film was removed were laminated, and the rolls were placed between the rolls and the rolls (the temperature of the upper and lower rolls was set to 110 ° C, the line load was set to 3.3 kgf/cm, and the line speed was set to 0.5 m/min) was subjected to compression by 10 times to be aligned, and further compressed at 150 ° C for 10 minutes under a pressure of 6 kg/cm ² to crosslink and harden it to obtain a soft magnetic sheet. The soft magnetic sheet produced has a large specific ratio, and the magnetic properties are reduced even under high temperature, high temperature and high humidity environments.

In Example 5B, except that the compression using a laminator was not carried out, the operation of Example 4B was repeated, whereby a cross-linked hardened soft magnetic sheet was obtained. The soft magnetic sheet produced has a large specific ratio, and the magnetic properties are reduced even under high temperature, high temperature and high humidity environments.

In the same manner as in Example 4B, except that the drying temperature of the soft magnetic coating applied to the peeled PET film was set to 125 ° C, the crosslinked hardened soft magnetic sheet was obtained. The soft magnetic sheet prepared is partially softened by blocking the blocked group of the isocyanate when the soft magnetic coating is dried at 125 ° C, so the value of μ' and specific gravity is slightly smaller than that of the case of Example 4B, but it is practical. No problem value.

In Comparative Example 3B, in the same manner as in Example 4B, except that an isocyanate (Celenet HL, manufactured by Nippon Polyurethane Co., Ltd.) was used instead of the blocked isocyanate, a crosslinked-hardened soft magnetic sheet was obtained. In the obtained soft magnetic sheet, since the unblocked isocyanate was used, the isocyanate was crosslinked with the phosphorus-containing polyester resin in the drying step, and the specific gravity was not increased.

In Comparative Example 4B, except that the blocked isocyanate was not used, and the drying temperature of the soft magnetic coating was set to 120 ° C, the operation of Example 4B was repeated, whereby an uncured soft magnetic sheet was obtained. Then, five sheets of the uncured soft magnetic sheet from which the PET film was removed were laminated, and the laminate was compressed without being subjected to laminator compression at a pressure of 6 kg/cm ² at 150 ° C for 10 minutes to obtain a soft magnetic property. sheet. Since the obtained soft magnetic sheet is not crosslinked, the specific gravity and magnetic properties after the environmental test are lowered.

The magnetic properties (magnetic permeability μ', magnetic loss μ", coefficient of performance Q) and specific gravity of the obtained cross-linked hardened soft magnetic sheets (Examples 4B to 6B and Comparative Examples 3B to 4B) were measured. The magnetic properties (μ', μ", Q) of the soft magnetic sheet after 192 hours in a high-temperature and high-humidity environment of 60 ° C and 95% Rh were maintained, and the specific gravity change rate of the soft magnetic sheet before and after the environmental test was determined. The change rate of μ' was evaluated in the same manner as in the case of Example 1A. The results are shown in Table 4.

Further, the determination of the magnetic properties was carried out based on the following criteria using the magnetic permeability μ' as an index.

(Using Fe-Si-Al as a soft magnetic powder) ◎: 65 ≦μ' ○: 60 ≦ μ' < 65 Δ: 55 ≦ μ' < 60 ×: μ' < 55

In the same manner as in Example 5, except that the polyester resin (Bylon 500, manufactured by Toyobo Co., Ltd.) having a hydroxyl value of 5.0 KOHmg/g was used instead of the phosphorus-containing polyester resin, the operation of Example 1B was repeated. Thereby, a crosslinked hardened soft magnetic sheet was obtained. The soft magnetic sheet produced has a large specific ratio, and the magnetic properties are reduced even under high temperature, high temperature and high humidity environments.

The operation of Example 1B was repeated in the same manner as in Example 8B. The obtained soft magnetic sheet had a large specific gravity, and the magnetic properties were lowered even under a high-temperature dry environment and in a high-temperature and high-humidity environment, and this was an example having reproducibility.

In the same manner as in Example 9B, the blending amount of the phosphorus-containing polyester resin was changed from 100 parts by weight to 75 parts by weight, and 25 parts by weight of melamine cyanurate (MC610, manufactured by Nissan Chemical Industries Co., Ltd.) was further mixed. The operation of Example 1B, whereby a crosslinked hardened soft magnetic sheet was obtained. The soft magnetic sheet produced has a large specific ratio, and the magnetic properties are reduced even under high temperature, high temperature and high humidity environments. In addition, after the combustion test, the UL94 V-0 standard can also be met.

In Comparative Example 5B, except that the blocked isocyanate was not used, the operation of Example 7B was repeated, whereby a crosslinked hardened soft magnetic sheet was obtained. Since the obtained soft magnetic sheet was not crosslinked, the specific gravity and magnetic properties after the environmental test were lowered.

Comparative Example 6B was prepared by using an externally added phosphorus-based polyester resin (polyester (Bylon 500, Toyobo Co., Ltd.): phosphate ester (CR741, Da Ba Chemical Co., Ltd. = 100:3) instead of the phosphorus-containing polyester resin. The same operation as in Example 8B was repeated, whereby a crosslinked hardened soft magnetic sheet was obtained. The laminated soft magnetic sheet obtained was found to be peeled off on the layer, and the soft magnetic sheet was peeled off and separated into a piece of soft magnetic sheet after the environmental test.

Comparative Example 7B According to the mixing (parts by weight) shown in Table 5, a phosphorus-containing polyester resin (Bylon 537, manufactured by Toyobo Co., Ltd.) and a flat soft magnetic powder (Fe-Si-Cr-Ni, manufactured by JEMCO Co., Ltd.) were mixed. And a blocked isocyanate (Colenet 2507, Japan Polyurethane Co., Ltd.) to prepare a soft magnetic coating, and the soft magnetic coating was applied to a peeling PET film by a roll coater so that the solid content of the coating became 180 g/m ² The company was dried at 115 ° C for 10 minutes to obtain an uncured soft magnetic sheet supported by a peeled PET film.

Then, five sheets of the uncured soft magnetic sheet from which the PET film was removed were laminated, and the rolls were placed between the rolls of the laminator (the temperature of the upper and lower rolls was set to 110 ° C, the line load was set to 3.3 kgf/cm, and the traveling speed was set to 0.5 m/min) was subjected to compression by 10 times to be aligned, and was compressed at 150 ° C for 10 minutes under a pressure of 6 kg/cm ² to thereby cross-link and harden it to obtain a soft magnetic sheet. Since the obtained soft magnetic sheet did not use a decane coupling agent, the specific gravity did not increase even if it was compressed.

The magnetic properties (magnetic permeability μ', magnetic loss μ", coefficient of performance Q) and specific gravity of the obtained cross-linked hardened soft magnetic sheets (Examples 7B to 9B and Comparative Examples 5B to 7B) were measured. Magnetic properties of soft magnetic sheets after 192 hours of high temperature and high temperature and high temperature and high humidity (high temperature drying conditions: 85%, 10% Rh; high temperature and high humidity conditions: 60 ° C, 95% Rh) ', μ', Q), and the specific gravity change rate and the μ' change rate of the soft magnetic sheet before and after the environmental test were determined, and evaluated in the same manner as in the case of Example 1A. The results are shown in Table 5.

Further, the determination of the magnetic properties was carried out based on the following criteria using the magnetic permeability μ' as an index.

(Fe-Si-Cr-Ni is used as the soft magnetic powder) ◎: 42 ≦μ' ○: 38 ≦ μ' < 42 Δ: 34 ≦ μ' < 38 ×: μ' < 34

In Example 10B, except that the polyester resin (Bylon 500, manufactured by Toyobo Co., Ltd.) having a hydroxyl value of 5.0 KOHmg/g was used instead of the phosphorus-containing polyester resin as shown in Table 6, the operation of Example 4B was repeated. Thereby, a crosslinked hardened soft magnetic sheet was obtained. The soft magnetic sheet produced has a large specific ratio, and the magnetic properties are reduced even under high temperature, high temperature and high humidity environments.

In the embodiment 11B, the operation of the example 4B was repeated, and the obtained soft magnetic sheet was large in size, and the magnetic properties were lowered even in a high-temperature, high-temperature, high-humidity environment, and it was an example having reproducibility.

In the same manner as in Example 4, the operation of Example 4B was repeated, except that 35 parts by weight of melamine cyanurate (MC610, manufactured by Nissan Chemical Industries Co., Ltd.) was further mixed, whereby a crosslinked hardened soft magnetic sheet was obtained. The soft magnetic sheet produced has a large specific ratio, and the magnetic properties are reduced even under high temperature, high temperature and high humidity environments. In addition, after the combustion test, the UL94 V-0 standard can also be met.

Comparative Example 8B was subjected to the operation of Example 10B repeatedly except that the blocked isocyanate was not used, whereby a crosslinked hardened soft magnetic sheet was obtained. Since the obtained soft magnetic sheet was not crosslinked, the specific gravity and magnetic properties after the environmental test were lowered.

Comparative Example 9B was prepared by using an externally added phosphorus-based polyester resin (polyester (Bylon 500, Toyobo Co., Ltd.): phosphate ester (CR741, Da Ba Chemical Co., Ltd. = 100:3) instead of the phosphorus-containing polyester resin. The operation of Example 11B was repeated, whereby a crosslinked hardened soft magnetic sheet was obtained. The laminated soft magnetic sheet obtained was found to be peeled off on the layer, and the soft magnetic sheet was peeled off and separated into a piece of soft magnetic sheet after the environmental test.

In Comparative Example 10B, a phosphorus-containing polyester resin (Bylon 537, manufactured by Toyobo Co., Ltd.) and a flat soft magnetic powder (Fe-Si-Al, manufactured by Kate Co., Ltd.) were mixed in accordance with the mixing (parts by weight) shown in Table 6. And a blocked isocyanate (Colenet 2507, Japan Polyurethane Co., Ltd.) to prepare a soft magnetic coating, and the soft magnetic coating was applied to a peeling PET film by a roll coater so that the solid content of the coating became 180 g/m ² The company was dried at 115 ° C for 10 minutes to obtain an uncured soft magnetic sheet supported by a peeled PET film.

Then, five sheets of the uncured soft magnetic sheet from which the PET film was removed were laminated, and the rolls were placed between the rolls of the laminator (the temperature of the upper and lower rolls was set to 110 ° C, the line load was set to 3.3 kgf/cm, and the traveling speed was set to The soft magnetic sheet was obtained by compressing 10 times to thereby align it, and subjecting it to an orientation at 150 ° C for 10 minutes under a pressure of 6 kg/cm ² . Since the obtained soft magnetic sheet does not use a decane coupling agent, the specific gravity does not increase even if it is compressed.

The magnetic properties (magnetic permeability μ', magnetic loss μ", coefficient of performance Q) and specific gravity of the obtained cross-linked hardened soft magnetic sheets (Examples 10B to 12B and Comparative Examples 8B to 10B) were measured. Magnetic properties of soft magnetic sheets (μ' after 192 hours of high temperature and high temperature and high temperature and high humidity (high temperature conditions: 85%, 10% Rh; high temperature and high humidity conditions: 60 ° C, 95% Rh) (μ) and Q), and the specific gravity change rate and the μ' change rate of the soft magnetic sheet before and after the environmental test were determined, and evaluated in the same manner as in the case of Example 1A. The results are shown in Table 6.

Further, the determination of the magnetic properties was carried out based on the following criteria using the magnetic permeability μ' as an index.

(Using Fe-Si-Al as a soft magnetic powder) ◎: 65 ≦μ' ○: 60 ≦ μ' < 65 Δ: 55 ≦ μ' < 60 ×: μ' < 55

In Example 13B to Example 17B and Comparative Example 11B to 12B, a phosphorus-containing polyester resin (Bylon 537, manufactured by Toyobo Co., Ltd.) and a flat soft magnetic powder (Fe-Si-) were mixed according to the mixing (parts by weight) of Table 7. Cr-Ni, manufactured by JEMCO Co., Ltd., decane coupling agent, IPA and blocked isocyanate (Colenet 2507, Japan Polyurethane Co., Ltd.) were mixed to prepare a soft magnetic coating, and the soft magnetic coating was coated with a roll coater to make a coating solid. The composition was applied to a release PET film (Teijin Co., Ltd.) in a form of 180 g/m ² , and dried at 115 ° C for 10 minutes to obtain an uncured soft magnetic sheet supported by a release PET film.

Further, the particle diameter percentage, the specific surface area, the saturation magnetization, the coercive force, the knocking degree, and the flatness of the soft magnetic powder to be used are shown in Table 7.

The magnetic properties (magnetic permeability μ', magnetic loss μ", coefficient of performance Q) and specific gravity of the obtained cross-linked hardened soft magnetic sheets (Examples 13B to 17B and Comparative Examples 11B to 12B) were measured and held. Magnetic properties of soft magnetic sheets after 192 hours in a high temperature dry environment or in a high temperature and high humidity environment (high temperature drying conditions: 85%, 10% Rh; high temperature and high humidity conditions: 60 ° C, 95% Rh) (μ) and Q), and the specific gravity change rate and the magnetic permeability μ' change rate of the soft magnetic sheet before and after the environmental test were determined, and evaluated in the same manner as in the case of Example 1A. The results are shown in Table 7.

Further, the determination of the magnetic properties was carried out based on the following criteria using the magnetic permeability μ' as an index.

(Fe-Si-Cr-Ni is used as the soft magnetic powder) ◎: 42 ≦μ' ○: 38 ≦ μ' < 42 Δ: 34 ≦ μ' < 38 ×: μ' < 34

As can be seen from Table 7, the soft magnetic sheets of Examples 13B to 17B have a knocking degree in the range of 0.55 to 1.45 g/ml, and a specific surface area in the range of 0.4 to 1.20 m ² /g, and the magnetic permeability μ' and The Q values are all large.

On the other hand, in the soft magnetic sheet of Comparative Example 11B, since the knocking degree exceeded 1.45 g/ml and the specific surface area was less than 0.4 m ² /g, the Q value was large, but the magnetic permeability μ' value was small. In the soft magnetic sheet of Comparative Example 12B, since the knocking degree was less than 0.55 g/ml and the specific surface area exceeded 1.20 m ² /g, the magnetic permeability μ' value was large, but the Q value was small.

In Example 18B and Comparative Example 13B, a soft magnetic sheet of Example 15B (having cross-linking) and Comparative Example 2B (without cross-linking) was placed between the antenna device and the separator on a mobile phone, and before and after the environmental test (60) Communication distance of °C, 95% Rh, 192hr). The results are shown in Table 8.

As can be seen from Table 8, the communication distance of the soft magnetic sheet of Example 18B which crosslinked the binder resin was determined to be no soft change before and after the environmental test, and the soft magnetic property of Comparative Example 13B which did not crosslink the binder resin. The communication distance of the film has changed greatly before and after the environmental test.

Industrial availability

The soft magnetic material of the present invention is suitable for high-temperature or high-temperature and high-humidity environments, and is suitable for small-sized and small-sized magnetic properties, because the soft magnetic material is cross-linked in a state in which the soft magnetic powder is closely aligned to increase the specific gravity. Equipment, such as antenna modules and mobile communication terminals.

Claims (25)

A soft magnetic material comprising at least a flat soft magnetic powder dispersed in a crosslinked polyester resin having a glass transition temperature of -20 to 40 ° C and a hydroxyl value of 4.5 mg KOH / g to 15 mg KOH / g. The soft magnetic material contains 400 to 600% by weight of the flat soft magnetic powder, and 60 to 150% by weight of the crosslinked polyester resin. The soft magnetic material according to claim 1, wherein the flat soft magnetic powder is oriented in substantially the same in-plane direction. A soft magnetic material as claimed in claim 1 or 2, which is in the form of a sheet. A soft magnetic material according to claim 1 or 2, wherein the polyester resin is crosslinked by using a blocked isocyanate. A soft magnetic material according to claim 1 or 2, wherein the polyester resin has flame retardancy. A soft magnetic material according to claim 5, wherein the polyester resin is a polyester resin containing phosphorus. A soft magnetic material according to claim 6, wherein the phosphorus-containing polyester resin has a phosphoric acid residue in a molecule. A soft magnetic material according to claim 1 or 2, wherein the flat soft magnetic powder is subjected to a decane coupling treatment. A soft magnetic material according to claim 1 or 2, wherein the flat soft magnetic powder is covered with an insulating layer. Such as the soft magnetic material of the ninth patent application, wherein the insulation The layer is a metal oxide film or a resin film. The soft magnetic material according to claim 1 or 2, wherein the flat soft magnetic powder is Fe-Si-Al alloy powder or Fe-Si-Cr-Ni alloy powder. For example, the soft magnetic material of claim 11 wherein the Fe-Si-Cr-Ni alloy powder has a knocking degree of 0.55 to 1.45 g/ml, a specific surface area of 0.45 to 1.20 m ² /g, and a flatness of 8~24. As in the soft magnetic material of claim 1 or 2, the real part μ' of the composite relative magnetic permeability is 35 or more. For example, the soft magnetic material of claim 1 or 2 has a specific gravity of 3.0 or more. For example, the soft magnetic material of claim 1 or 2 is subjected to a dimensional change of 3% or less after being placed in an environment of 60 ° C to 95 ° C. For example, the soft magnetic material of claim 1 or 2 is placed at a temperature of 40 ° C to 90 ° C and a relative humidity of 60 to 95% in a high temperature and high humidity environment, and the dimensional change is 3% or less. An electronic device characterized by having a soft magnetic material according to any one of claims 1 to 16. An antenna module characterized in that a support body having an antenna coil is formed, and a soft magnetic material according to any one of claims 1 to 16 is laminated. The antenna module of claim 18, wherein the antenna coil is electrically connected to the signal processing circuit unit. Such as the antenna module of claim 18 or 19, wherein The metal spacer is laminated on the support opposite to the side on which the soft magnetic material is laminated. A mobile communication terminal, comprising: the antenna module of any one of claims 18 to 20. A method for producing a soft magnetic material, which comprises mixing at least a flat soft magnetic powder, a polyester resin having a hydroxyl value of 4.5 mgKOH/g to 15 mgKOH/g and a glass transition temperature of -20 to 40 ° C, a crosslinking agent and a solvent. The soft magnetic composition of the composition is applied onto the release substrate, dried at a temperature at which the crosslinking reaction does not substantially occur, and is compressed at a temperature at which the crosslinking reaction occurs. The production method according to claim 22, wherein the drying is carried out at a temperature at which the crosslinking reaction does not substantially occur, and the compression is carried out at a temperature at which the crosslinking reaction does not substantially occur before the compression at the temperature at which the crosslinking reaction occurs. . A method for producing a laminated soft magnetic sheet, which comprises at least a flat soft magnetic powder, a polyester resin having a hydroxyl value of 4.5 mgKOH/g to 15 mgKOH/g and a glass transition temperature of -20 to 40 ° C, a crosslinking agent and a solvent. After the soft magnetic composition having the mixed structure is applied onto the release substrate, it is dried at a temperature at which the crosslinking reaction does not substantially occur, and the release substrate is removed and repeatedly performed to obtain at least two soft magnetic compositions. The sheet is dried, and at least two dried sheets are laminated to be compressed at a temperature at which a crosslinking reaction occurs. The production method according to claim 24, wherein at least two of the dried sheets are laminated, and then compressed at a temperature at which the crosslinking reaction does not substantially occur before compression at a temperature at which the crosslinking reaction occurs.