WO2018066162A1 - Method for producing flexible permanent magnet, flexible permanent magnet, deformation detection sensor, and deformation detection method - Google Patents

Abstract

In this method for producing a flexible permanent magnet provided with a magnetic filler 2, and a polymer matrix layer 3 including the magnetic filler 2 dispersed therein, a compressive force P is applied to the sheet-shaped polymer matrix layer 3 to deform the polymer matrix layer, and a magnetic field is applied while the polymer matrix layer 3 is in a state of having been compressed and deformed, to set the surface magnetic flux density higher in central portions of pole surfaces than in end portions of the pole surfaces. Accordingly, a flexible permanent magnet having a higher surface magnetic flux density in the central portions of the pole surfaces than in the end portions of the pole surfaces can be obtained, and a contribution to an improvement in detection sensitivity can be made.

Description

Method for manufacturing flexible permanent magnet, flexible permanent magnet, deformation detection sensor, and deformation detection method

The present invention relates to a method for producing a flexible permanent magnet having a polymer matrix layer containing a dispersed magnetic filler, and further relates to the flexible permanent magnet, a deformation detection sensor and a deformation detection method using the same. .

Sealed secondary batteries typified by lithium ion secondary batteries (hereinafter sometimes referred to simply as “secondary batteries”) are not only mobile devices such as mobile phones and laptop computers, but also electric vehicles and hybrid vehicles. It is also used as a power source for electric vehicles. A cell constituting a secondary battery includes an electrode group in which a positive electrode and a negative electrode are wound or laminated with a separator interposed therebetween, and an exterior body that houses the electrode group. In general, a laminate film such as an aluminum laminate foil or a cylindrical or square metal can is used for the exterior body.

Currently, a technique for detecting deformation of a secondary battery and using it for various analysis, determination, control and the like is being studied. For example, in Patent Document 1 by the present applicant, a technique is proposed in which deformation of two or more secondary batteries constituting an assembled battery is detected by a deformation detection sensor to determine that an abnormality has occurred in a specific secondary battery. Has been. This deformation detection sensor includes a flexible permanent magnet having a polymer matrix layer containing a magnetic filler dispersed therein, and a detector disposed opposite to the polymer matrix, and is attached to a secondary battery. The change in the magnetic field accompanying the deformation of the layer is detected by a detector, and the deformation of the secondary battery is detected based on the change.

Usually, the detector is arranged so as to face the central portion of the magnetic pole surface of the flexible permanent magnet so that it can cope with even a slight displacement. However, it has been found that conventional flexible permanent magnets tend to have a low surface magnetic flux density at the center of the magnetic pole surface, and there is room for improvement in order to increase the sensitivity of detection. Such a tendency of the surface magnetic flux density is due to the fact that the flexible permanent magnet is formed as a sheet-like single-pole magnetized magnet having magnetic pole faces of different polarities on both sides (FIG. 1, 2), in the applications as described above, there is a fact that such a magnet form is unavoidable.

In Patent Document 2, magnetic powder dispersed in a matrix is magnetically oriented at a high temperature, and the rubber magnet sheet is cooled while compressed in a direction perpendicular to the magnetic field direction, and the compression is released. A technique of vulcanizing a rubber magnet sheet after demagnetizing and magnetizing the obtained vulcanized sheet is described. However, this is a technique for maintaining the orientation state of the magnetic field, and cannot solve the above-described problem relating to detection sensitivity.

Patent Document 3 describes a permanent magnet in which a plurality of magnetic poles are formed on a flat surface portion to focus lines of magnetic force in order to improve the torque of an actuator. However, in order to produce this permanent magnet, it is necessary to perform multipolar magnetization using a magnetized yoke having a complicated structure, and thus the manufacturing cost tends to increase. Of course, this permanent magnet is a sintered magnet used in a magnetic circuit for an actuator and does not have flexibility.

JP 2016-27539 A JP 2006-156423 A JP 2001-76925 A

The present invention has been made in view of the above circumstances, and its object is to produce a flexible permanent magnet that contributes to improvement in detection sensitivity, the flexible permanent magnet, a deformation detection sensor using the same, and deformation detection. It is to provide a method.

The method for producing a flexible permanent magnet according to the present invention is the method for producing a flexible permanent magnet having a magnetic filler and a polymer matrix layer containing the magnetic filler dispersed therein, wherein the high The molecular matrix layer is deformed by applying an external force, and a magnetic field is applied in a state where the polymer matrix layer is deformed, thereby increasing the surface magnetic flux density at the central portion rather than the end portion of the magnetic pole surface. In this method, since a magnetic field is applied in a state where the polymer matrix layer is deformed by applying an external force, the direction of the lines of magnetic force can be changed when the external force is removed to return to the original shape. By utilizing this, a flexible permanent magnet having a higher surface magnetic flux density at the center than at the end of the magnetic pole surface can be obtained, which can contribute to an improvement in detection sensitivity.

Preferably, the polymer matrix layer is deformed by applying a compressive force in the thickness direction as the external force, and the magnetic field is applied in the thickness direction of the deformed polymer matrix layer. According to this method, a desired flexible permanent magnet can be obtained by simpler work. In this case, it is desirable to apply the compression force so that the compression ratio is 5 to 50%.

It is preferable that the magnetic filler is unevenly distributed in the thickness direction of the polymer matrix layer. In this case, since the area | region with few magnetic fillers becomes flexible, when an external force is applied, it is easy to deform | transform a polymer matrix layer.

The flexible permanent magnet according to the present invention is a flexible permanent magnet having a magnetic filler and a polymer matrix layer containing the magnetic filler dispersed therein, on both surfaces of the polymer matrix layer forming a sheet shape. The magnetic pole surfaces having different polarities are provided, and the surface magnetic flux density at the central portion is higher than the end portions of the magnetic pole surfaces. Since this flexible permanent magnet has a higher surface magnetic flux density at the center than at the end of the magnetic pole surface, it contributes to improved detection sensitivity. The flexible permanent magnet preferably has an elastic modulus of 0.5 to 40 MPa.

A deformation detection sensor according to the present invention includes the above-described flexible permanent magnet and a detector configured to be able to detect a change in a magnetic field accompanying deformation of the polymer matrix layer. Since the deformation detection sensor includes a flexible permanent magnet having a surface magnetic flux density higher in the central portion than in the end portion of the magnetic pole surface, it is excellent in detection sensitivity.

In the deformation detection method according to the present invention, the flexible permanent magnet described above is affixed to a detection object, and the change in the magnetic field accompanying the deformation of the polymer matrix layer is detected by a detector. Is detected. This deformation detection method uses a flexible permanent magnet having a higher surface magnetic flux density at the central portion than at the end portion of the magnetic pole surface, and therefore has excellent detection sensitivity. The object to be detected may be, for example, a sealed secondary battery represented by a lithium ion secondary battery.

Sectional view schematically showing a flexible permanent magnet with normal single pole magnetization The graph which shows the measurement result of the surface magnetic flux density of the magnet of FIG. Sectional drawing which shows the precursor of a flexible permanent magnet typically Sectional drawing which shows a mode that a flexible permanent magnet is manufactured by this invention Sectional drawing which shows typically an example of the flexible permanent magnet which concerns on this invention The graph which shows the measurement result of the surface magnetic flux density of the magnet of FIG. (A) perspective view and (b) AA cross-sectional view schematically showing a sealed secondary battery Sectional drawing schematically showing the polymer matrix layer when compressive force is applied Sectional drawing schematically showing the polymer matrix layer when compressive force is applied The graph which shows the measurement result of the surface magnetic flux density in the comparative example 1 The graph which shows the measurement result of the surface magnetic flux density in the comparative example 2 The graph which shows the measurement result of the surface magnetic flux density in Example 1 The graph which shows the measurement result of the surface magnetic flux density in Example 2 The graph which shows the measurement result of the surface magnetic flux density in Example 3 The graph which shows the measurement result of the surface magnetic flux density in Example 4 The graph which shows the measurement result of the surface magnetic flux density in Example 5 The graph which shows the measurement result of the surface magnetic flux density in Example 6

First, for reference, FIG. 1 shows a cross section of a flexible permanent magnet manufactured by normal single pole magnetization. The flexible permanent magnet 91 includes a magnetic filler 92 and a polymer matrix layer 93 containing the magnetic filler 92 dispersed therein. The magnet 91 is formed as a single-pole magnetized magnet having magnetic pole faces with different polarities on both surfaces of the polymer matrix layer 93 in the form of a sheet, and the magnetic filler 92 extends along the thickness direction of the polymer matrix layer 93. Uniformly magnetized. The drawings are drawn schematically, and actually, smaller magnetic fillers 92 are finely dispersed with respect to the cross section of the magnet 91 (the same applies to other cross sectional views).

FIG. 2 shows the measurement results of the surface magnetic flux density for a magnet 91 having a circular sheet shape with a diameter of 20 mm and a thickness of 1 mm. The horizontal axis of the graph is the radial direction (width direction) position of the magnet 91, and 0 mm and 20 mm correspond to the end positions, respectively. The surface magnetic flux density is a measured value at a position 2 mm away from the magnetic pole surface, which is the N-polar surface, in the thickness direction, and specifically conforms to the measurement method of the example. As shown in FIG. 2, in this magnet 91, the surface magnetic flux density is low at the central portion of the magnetic pole surface, and this tendency is considered to be stronger as the magnet is thinner and flatter. This is disadvantageous in detecting the deformation of the detected object as described later, and there is room for further improvement in order to increase the detection sensitivity.

Therefore, in this embodiment, an external force is applied to the polymer matrix layer in the form of a sheet to deform it (an external force applying step), and a magnetic field is applied in a state where the polymer matrix layer is deformed (a magnetizing step). Thus, the surface magnetic flux density at the center portion is made higher than the end portion of the magnetic pole surface. In this method, since a magnetic field is applied in a state where the polymer matrix layer is deformed by applying an external force, the direction of the lines of magnetic force can be changed when the external force is removed to return to the original shape. By utilizing this, a flexible permanent magnet having a higher surface magnetic flux density at the center than at the end of the magnetic pole surface can be obtained, which can contribute to an improvement in detection sensitivity. Further, it is not necessary to use a magnetized yoke having a complicated structure, and the manufacturing cost can be reduced. More specific description will be given below.

FIG. 3 shows a cross section of the precursor of the flexible permanent magnet. This precursor 10 contains a magnetic filler 2 dispersed in a polymer matrix layer 3 in the form of a sheet. The magnetic filler 2 has not been magnetized yet, and the precursor 10 has no magnetic force. By applying a magnetic field to the precursor 10 to magnetize the magnetic filler 2, a flexible permanent magnet having the magnetic filler 2 and the polymer matrix layer 3 containing the magnetic filler 2 dispersed therein is obtained. It is done. The precursor 10 undergoes a step (preparation step) for preparing a precursor solution by stirring and mixing the magnetic filler 2 and a matrix material made of an elastomer component, and a step (curing step) for curing the precursor solution. Molded.

In the precursor 10 of FIG. 3, when a magnetic field is applied in the thickness direction (vertical direction of FIG. 3) in this state, only the magnet 91 as shown in FIG. 1 is obtained. Therefore, in this embodiment, when applying a magnetic field, the polymer matrix layer 3 having a sheet shape is deformed by applying an external force. In FIG. 4, the polymer matrix layer 3 is deformed by applying a compressive force P in the thickness direction as an external force, and a magnetic field is applied in the thickness direction of the deformed polymer matrix layer 3. The deformation of the polymer matrix layer 3 is elastic deformation. In the present embodiment, the polymer matrix layer 3 to which the compressive force P is applied is deformed so as to widen (expand) toward one side in the thickness direction (the lower side in FIG. 4).

In the present embodiment, in a natural state where no external force is applied, the cross-sectional shape of the polymer matrix layer 3 is rectangular (see FIG. 3), and both surfaces thereof have the same area. In a state where it is deformed so as to widen toward one side in the thickness direction as shown in FIG. The arrow MD indicates the magnetization direction (magnetization direction), which may be reversed. Although not shown, a magnetizing device is disposed around the polymer matrix layer 3. For example, the compression force P is obtained by sandwiching the polymer matrix layer 3 between a pair of yokes provided in the magnetizing device. Can be added. As the magnetizing device, for example, “ES-10100-15SH” manufactured by Electromagnetic Industry Co., Ltd. or “TM-YS4E” manufactured by Tamagawa Seisakusho Co., Ltd. can be used. Usually, a magnetic field of 1 to 8 T is applied.

FIG. 5 shows a flexible permanent magnet manufactured through the process of FIG. 4, and FIG. 6 shows the measurement result of the surface magnetic flux density for the magnet having a circular sheet shape with a diameter of 20 mm and a thickness of 1 mm. The method for measuring the surface magnetic flux density is the same as the graph of FIG. As shown in FIG. 6, in this magnet 1, the surface magnetic flux density at the center is higher than the end of the magnetic pole surface 1 a (N pole surface in the present embodiment). This is because the direction of the magnetic filler 2 changes when the compressive force P is removed and returned to its original shape, and in a natural state where no external force is applied, in the space facing the central portion of the magnetic pole surface 1a. This is thought to be because the magnetic field lines converge toward the surface.

Here, the surface magnetic flux density at the end of the magnetic pole surface is the highest in the range of 30% of the width dimension (diameter) from the end position in the width direction (radial direction) to the center position on the magnetic pole surface. A value is used. Further, the highest value in the range of 15% of the width dimension (diameter) around the center position in the width direction (radial direction) on the magnetic pole surface is used for the surface magnetic flux density at the central portion of the magnetic pole surface. It is done. It is to be noted that the surface magnetic flux density is higher in the central portion than in the end portion, and the magnetic pole surface on one side is the magnetic pole surface 1a in the present embodiment, but the magnetic pole surface 1a is an N-pole surface. S pole face. Therefore, it is possible to increase the surface magnetic flux density in the central portion on either the N-pole surface or the S-pole surface.

When applying the magnetic field, it is preferable to apply the compressive force P so that the compressibility is 5 to 50%. Compression ratio, the thickness before the deformation in the polymer matrix layer 3 _{T 0,} the thickness after the deformation as _{T 1,} is determined by the equation of _{(T 0 -T 1) / T} 0. By setting the compression rate to 5% or more, the polymer matrix layer 3 can be appropriately deformed. Further, by setting the compression rate to 50% or less, breakage such as cracks can be prevented without excessively deforming the polymer matrix layer 3. The thickness T ₀ is, for example, 0.5 to 20 mm, and more preferably 1 to 5 mm.

In this embodiment, the magnet 1 in which the magnetic filler 2 is unevenly distributed in the thickness direction of the polymer matrix layer 3 is illustrated. The polymer matrix layer 3 has a two-layer structure of a first layer 31 composed of one region with relatively few magnetic fillers 2 and a second layer 32 composed of the other region with relatively many magnetic fillers 2. And their boundary surfaces are conceptually drawn by broken lines. The magnetic pole surface 1 a having a higher surface magnetic flux density in the central portion than the end portion is formed by the first layer 31, and the opposite magnetic pole surface 1 b is formed by the second layer 32.

The first layer 31 with few magnetic fillers 2 is relatively flexible and easy to move. Therefore, when an external force is applied as shown in FIG. 4, the first layer 31 is greatly deformed, and the polymer matrix layer 3 can be easily deformed so that the second layer 32 follows the first layer 31. In addition, the second layer 32 having a large amount of the magnetic filler 2 is advantageous in increasing the sensitivity of detection because the change in the magnetic field with respect to the deformation of the polymer matrix layer 3 is large. In the scene where deformation is detected, the sensor sensitivity to a low internal pressure is increased. In the case where the magnetic filler is unevenly distributed, the filler uneven distribution ratio obtained according to the measurement method of the example is preferably 0.55 or more, and more preferably 0.6 or more.

The magnet 1 having the uneven distribution structure as described above can be obtained by using a precursor 10 (see FIGS. 3 and 4) in which the magnetic filler 2 is unevenly distributed in the thickness direction of the polymer matrix layer 3. The precursor 10 can be molded by, for example, a method in which the magnetic filler 2 is introduced into a matrix material composed of an elastomer component, and then allowed to stand at room temperature or a predetermined temperature, and is allowed to settle naturally by the weight of the magnetic filler. The filler uneven distribution rate can be adjusted by changing the temperature and the time of placement. Alternatively, the magnetic filler may be unevenly distributed using a physical force such as centrifugal force or magnetic force.

In FIG. 4, in the polymer matrix layer 3 to which the compressive force P is applied, each of the first layer 31 and the second layer 32 is expanded toward one side in the thickness direction. It is not limited to this. Depending on conditions such as the uneven distribution rate of filler and frictional force, the magnet may be deformed as shown in FIGS. 7 and 8, but as described above, the permanent magnet has a higher surface magnetic flux density at the center than at the end of the pole face. As long as the above is obtained, such a modification may be used. In any of the cases of FIGS. 4, 7 and 8, the first layer 31 protrudes more outward in the width direction (radial direction) than the second layer 32. Further, in the second layer 32, the side (lower side) in contact with the first layer 31 protrudes greatly outward in the width direction (radial direction) as compared to the opposite side (upper side).

In the present embodiment, an example in which the polymer matrix layer is compressed and deformed by applying an external force has been shown. I can't. For example, an external force is applied to the polymer matrix layer to bend and deform into an arcuate shape, and a magnetic field is applied in a state where the polymer matrix layer is deformed. It can be high.

The flexible permanent magnet 1 shown in FIG. 5 has a magnetic filler 2 and a polymer matrix layer 3 containing the magnetic filler 2 dispersed therein. The magnet 1 is provided as a single-pole magnetized magnet with magnetic pole faces having different polarities on both surfaces of the polymer matrix layer 3 in the form of a sheet. As shown in FIG. 6, the surface magnetic flux density in the central portion is higher than the end portion of the magnetic pole surface, and this is considered to be because the magnetic field lines converge toward the space facing the central portion of the magnetic pole surface. Such a configuration can contribute to improvement in detection sensitivity.

The flexible permanent magnet 1 preferably has an elastic modulus of 0.5 to 40 MPa. Specifically, the elastic modulus is measured according to the measurement method of the embodiment. When the elastic modulus is 0.5 MPa or more, deformation due to its own magnetic force can be prevented, and the shape of the magnet can be maintained well. Moreover, when the elastic modulus is 40 MPa or less, the polymer matrix layer is easily deformed when an external force is applied. If this exceeds 40 MPa, cracks may occur when the polymer matrix layer is deformed.

As described above, in this embodiment, the magnetic filler 2 is unevenly distributed in the thickness direction of the polymer matrix layer 3, and the polymer matrix layer 3 includes the first layer 31 and the second layer 32. The first layer 31 may be formed of a foam containing the magnetic filler 2 and bubbles, whereby the polymer matrix layer 3 can be more easily deformed. The second layer 32 may be formed of a foam, and the entire polymer matrix layer 3 may be formed of a foam. As the foam, a general resin foam can be used, but in consideration of characteristics such as compression set, it is preferable to use a thermosetting resin foam such as a polyurethane resin foam or a silicone resin foam.

Examples of the magnetic filler 2 include ferrite, alnico, samarium cobalt, and neodymium. The shape of the magnetic filler 2 is not particularly limited, and may be any of a spherical shape, a flat shape, a needle shape, a columnar shape, and an indefinite shape. The average particle size of the magnetic filler 2 is preferably 0.02 to 500 μm, more preferably 0.1 to 400 μm, and still more preferably 0.5 to 300 μm. When the average particle size is smaller than 0.02 μm, the magnetic properties of the magnetic filler 2 tend to be reduced, and when the average particle size exceeds 500 μm, the mechanical properties of the magnet 1 tend to be lowered and become brittle.

The polymer matrix layer 3 is formed of a matrix material made of an elastomer component, and examples of the matrix material include rubber, polyurethane, silicone, polyethylene, vinyl chloride, and nylon. The amount of the magnetic filler 2 is preferably 1 to 450 parts by weight, more preferably 2 to 400 parts by weight with respect to 100 parts by weight of the elastomer component. If this is less than 1 part by weight, it tends to be difficult to detect changes in the magnetic field, and if it exceeds 450 parts by weight, the magnet 1 may become brittle.

As the elastomer component, a thermoplastic elastomer, a thermosetting elastomer, or a mixture thereof can be used. Examples of the thermoplastic elastomer include styrene-based thermoplastic elastomer, polyolefin-based thermoplastic elastomer, polyurethane-based thermoplastic elastomer, polyester-based thermoplastic elastomer, polyamide-based thermoplastic elastomer, polybutadiene-based thermoplastic elastomer, polyisoprene-based thermoplastic elastomer, A fluororubber-based thermoplastic elastomer can be used. Examples of the thermosetting elastomer include polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, polychloroprene rubber, nitrile rubber, diene synthetic rubber such as ethylene-propylene rubber, ethylene-propylene rubber, butyl rubber, acrylic rubber, Non-diene synthetic rubbers such as polyurethane rubber, fluorine rubber, silicone rubber, epichlorohydrin rubber, and natural rubber can be mentioned. Among these, a thermosetting elastomer is preferable because it is possible to suppress the sag of the elastomer accompanying heat generation and overload of the battery. More preferred is polyurethane rubber (also referred to as polyurethane elastomer) or silicone rubber (also referred to as silicone elastomer).

The polyurethane elastomer is obtained by reacting an active hydrogen-containing compound with an isocyanate component. When using a polyurethane elastomer as an elastomer component, an active hydrogen-containing compound and a magnetic filler are mixed, and an isocyanate component is mixed therein to obtain a mixed solution. Moreover, a liquid mixture can also be obtained by mixing a magnetic filler with an isocyanate component and mixing an active hydrogen-containing compound. In any method, a magnetic filler is mixed with a polymer matrix precursor containing an active hydrogen-containing compound and an isocyanate component to prepare a mixed solution. When a silicone elastomer is used as an elastomer component, a mixed liquid can be prepared by adding a magnetic filler to a precursor of a silicone elastomer and mixing them. In addition, you may add a solvent as needed.

As the isocyanate component that can be used in the polyurethane elastomer, compounds known in the field of polyurethane can be used. For example, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, p-phenylene Aromatic diisocyanates such as diisocyanate, m-phenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 1,6-hexamethylene diisocyanate 1,4-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, nor It can be mentioned alicyclic diisocyanates such as Renan diisocyanate. These may be used alone or in combination of two or more. The isocyanate component may be modified such as urethane modification, allophanate modification, biuret modification, and isocyanurate modification. Preferred isocyanate components are 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane disissocyanate, more preferably 2,4-toluene diisocyanate, 2,6-toluene diisocyanate.

As the active hydrogen-containing compound, a compound known in the field of polyurethane can be used. For example, polytetramethylene glycol, polypropylene glycol, polyethylene glycol, polyether polyol represented by copolymer of propylene oxide and ethylene oxide, polybutylene adipate, polyethylene adipate, representative of 3-methyl-1,5-pentane adipate Polyester polyol such as polyester polyol, polycaprolactone polyol, reaction product of polyester glycol and alkylene carbonate such as polycaprolactone, and the like, and the reaction of the resulting reaction mixture with organic polyol. Polyester polycarbonate polyol reacted with dicarboxylic acid, esterification of polyhydroxyl compound and aryl carbonate High molecular weight polyol polycarbonate polyols obtained by the reaction can be mentioned. These may be used alone or in combination of two or more.

In addition to the high molecular weight polyol component described above as the active hydrogen-containing compound, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, 1,4-bis (2-hydroxyethoxy) benzene, trimethylolpropane, glycerin, 1,2,6- Hexanetriol, pentaerythritol, tetramethylolcyclohexane, methylglucoside, sorbitol, mannitol, dulcitol, sucrose, 2,2,6,6-tetrakis (hydroxymethyl) cyclohexanol, and triethanol Low molecular weight polyol component of such emissions, ethylenediamine, tolylenediamine, diphenylmethane diamine, may be used low molecular weight polyamine component of diethylenetriamine. These may be used alone or in combination of two or more. Further, 4,4′-methylenebis (o-chloroaniline) (MOCA), 2,6-dichloro-p-phenylenediamine, 4,4′-methylenebis (2,3-dichloroaniline), 3,5-bis ( Methylthio) -2,4-toluenediamine, 3,5-bis (methylthio) -2,6-toluenediamine, 3,5-diethyltoluene-2,4-diamine, 3,5-diethyltoluene-2,6- Diamine, trimethylene glycol-di-p-aminobenzoate, polytetramethylene oxide-di-p-aminobenzoate, 1,2-bis (2-aminophenylthio) ethane, 4,4'-diamino-3,3 ' -Diethyl-5,5'-dimethyldiphenylmethane, N, N'-di-sec-butyl-4,4'-diaminodiphenylmethane, 4,4'-diamy -3,3'-diethyldiphenylmethane, 4,4'-diamino-3,3'-diisopropyl-5,5'-dimethyldiphenylmethane, 4,4'-diamino-3,3 ', 5,5'-tetraethyldiphenylmethane 4,4′-diamino-3,3 ′, 5,5′-tetraisopropyldiphenylmethane, m-xylylenediamine, N, N′-di-sec-butyl-p-phenylenediamine, m-phenylenediamine, and Polyamines exemplified by p-xylylenediamine and the like can also be mixed. Preferred active hydrogen-containing compounds are polytetramethylene glycol, polypropylene glycol, a copolymer of propylene oxide and ethylene oxide, 3-methyl-1,5-pentane adipate, more preferably a copolymer of polypropylene glycol, propylene oxide and ethylene oxide. It is a coalescence.

When a polyurethane elastomer is used, its NCO index is preferably 0.3 to 1.2, more preferably 0.35 to 1.1, and still more preferably 0.4 to 1.05. If the NCO index is less than 0.3, the elastomer tends to be insufficiently cured. If the NCO index is greater than 1.2, the elastic modulus increases and the sensor sensitivity tends to decrease.

A deformation detection sensor 5 for detecting deformation of the secondary battery 6 is attached to the sealed secondary battery 6 shown in FIG. The deformation detection sensor 5 includes a flexible permanent magnet 1 attached to a secondary battery 6 as an object to be detected, and a detector 4 configured to be able to detect a change in magnetic field accompanying deformation of the polymer matrix layer 3. Is provided. When the secondary battery 6 is deformed such as swelling, the polymer matrix layer 3 is deformed accordingly, and the change in the magnetic field accompanying the deformation of the polymer matrix layer 3 is detected by the detector 4. In this way, deformation of the secondary battery 6 can be detected with high sensitivity and without wiring.

The secondary battery 6 of the present embodiment is configured as a cell (single cell) in which an electrode group 62 is accommodated in a sealed exterior body 61. The electrode group 62 has a structure in which a positive electrode and a negative electrode are laminated or wound through a separator between them, and an electrolyte is held in the separator. The secondary battery 6 is a laminated battery using a laminated film such as an aluminum laminated foil as the exterior body 61, and specifically, a laminated lithium ion secondary battery having a capacity of 1.44 Ah. Although not shown, an assembled battery composed of a plurality of secondary batteries 6 is accommodated in the housing 60.

In the example of FIG. 9, since the magnet 1 is attached to the outer surface of the exterior body 61 of the secondary battery 6, the polymer matrix layer 3 can be deformed according to deformation (mainly swelling) of the exterior body 61. . The magnet 1 may be attached to the inner surface of the exterior body 61. Alternatively, the magnet 1 may be attached to the electrode group 62, and according to such a configuration, the polymer matrix layer 3 can be deformed according to deformation (mainly swelling) of the electrode group 62. The deformation of the secondary battery 6 to be detected may be any deformation of the exterior body 61 and the electrode group 62.

The detector 4 is disposed at a location where a change in the magnetic field can be detected, and is preferably affixed to a relatively rigid location that is not easily affected by the swelling of the secondary battery 6. In the present embodiment, the detector 4 is attached to the inner surface of the housing 60 as shown in FIG. The housing 60 of the battery module is formed of, for example, metal or plastic, and a laminate film may be used. Although the detector 4 is arranged close to the polymer matrix layer 3 in the drawing, it may be arranged away from the polymer matrix layer 3.

For the detector 4, for example, a magnetoresistive element, a Hall element, an inductor, an MI element, a fluxgate sensor, or the like can be used. Examples of the magnetoresistive element include a semiconductor compound magnetoresistive element, an anisotropic magnetoresistive element (AMR), a giant magnetoresistive element (GMR), and a tunnel magnetoresistive element (TMR). Among these, the Hall element is preferable because it has high sensitivity over a wide range and is useful as the detector 4. As the Hall element, for example, EQ-432L manufactured by Asahi Kasei Electronics Corporation can be used.

When the magnet 1 is affixed to the secondary battery 6 that is the object to be detected, the magnetic pole surface 1a (forming the first layer 31) having a higher surface magnetic flux density at the center than at the end is directed toward the detector 4. Thus, the detection sensitivity can be increased. The detector 4 is arranged so as to face the central portion of the magnetic pole face so that it can cope with a slight positional deviation. In this magnet 1, since the surface magnetic flux density is higher in the central portion than in the end portion of the magnetic pole surface 1a, the detection sensitivity can be increased.

The detection signal output from the detector 4 is sent to a control device (not shown). When a change in a magnetic field equal to or greater than a set value is detected by the detector 4, a switching circuit (not shown) connected to the control device. Interrupts energization and stops charging or discharging current. According to such a configuration, troubles such as rupture of the secondary battery can be prevented based on the result of detecting the deformation of the secondary battery.

In the present embodiment, an example in which the sealed secondary battery is a lithium ion secondary battery is shown, but the present invention is not limited to this. The secondary battery used is not limited to a non-aqueous electrolyte secondary battery such as a lithium ion battery, and may be an aqueous electrolyte secondary battery such as a nickel metal hydride battery. Further, the detection target is not limited to a sealed secondary battery.

In this embodiment, an example in which a flexible permanent magnet is used for detecting deformation of a secondary battery has been shown. However, the present invention is not limited to this, and in other applications such as a proximity sensor and a motor, Alternatively, the above-described flexible permanent magnet having a high surface magnetic flux density at the center can also be used.

The present invention is not limited to the embodiment described above, and various improvements and modifications can be made without departing from the spirit of the present invention.

Examples that specifically illustrate the configuration and effects of the present invention will be described.

Comparative Example 1
A silicone elastomer (“SE1740”), which will be described later, was used as a matrix material for the polymer matrix layer, and a precursor in which the magnetic filler was unevenly distributed in the thickness direction of the polymer matrix layer was molded. When a magnetic field was applied to the precursor, a flexible permanent magnet was produced by ordinary single pole magnetization without compressing the polymer matrix layer (compression rate 0%). Magnetization was performed at 2.0 T using a magnetizing apparatus (TM-YS4E, manufactured by Tamagawa Seisakusho Co., Ltd.).

The molding process of the precursor using SE1740 is as follows. Add 466.7 parts by weight of MQP-14-12 (Moricope Magnequench, neodymium filler, average particle size 50 μm) to 100 parts by weight of DOW CORNING® SE1740A (manufactured by Toray Dow Corning, silicone). A filler dispersion was prepared. Add 100 parts by weight of DOW CORNING (R) SE1740B (manufactured by Dow Corning, Toray, silicone), mix and degas with a rotating / revolving mixer (Sinky) to prepare a reaction solution containing magnetic filler did. This reaction solution was dropped on a polyethylene terephthalate film subjected to a release treatment, and the thickness was adjusted to 2.0 mm with a doctor blade. This was allowed to stand at room temperature for 5 minutes and subjected to uneven distribution treatment, and then cured at 90 ° C. for 15 hours to form a precursor in which the magnetic filler was unevenly distributed in the thickness direction of the polymer matrix layer.

Comparative Example 2
A silicone elastomer (“SilGel612”), which will be described later, was used as a matrix material for the polymer matrix layer, and a precursor in which the magnetic filler was hardly unevenly distributed in the polymer matrix layer was molded. When a magnetic field was applied to the precursor, a flexible permanent magnet was produced by ordinary single pole magnetization without compressing the polymer matrix layer (compression rate 0%). Magnetization was performed at 2.0 T using the magnetizing apparatus.

The molding process of the precursor using SilGel612 is as follows. To 140 parts by weight of WACKER-12SilGel612A (manufactured by Asahi Kasei Wacker Silicone, silicone), 560 parts by weight of MQP-14-12 (manufactured by Moricope Magnequench, neodymium filler, average particle size 50 μm) was added to prepare a filler dispersion. . To this, 100 parts by weight of WACKER SilGel612B (manufactured by Asahi Kasei Wacker Silicone Co., Ltd.) was added and mixed and defoamed with a rotating / revolving mixer (Sinky Co., Ltd.) to prepare a reaction liquid containing a magnetic filler. This reaction solution was dropped on a polyethylene terephthalate film subjected to a release treatment, and the thickness was adjusted to 2.0 mm with a doctor blade. This was cured at 90 ° C. for 15 hours to form a precursor in which the magnetic filler was hardly unevenly distributed in the polymer matrix layer.

Example 1
As a matrix material to be a polymer matrix layer, an in-house manufactured polyurethane elastomer (“polyurethane A”) described later was used, and a precursor in which magnetic fillers were unevenly distributed in the thickness direction of the polymer matrix layer was molded. When a magnetic field was applied to the precursor, the polymer matrix layer was compressed (compression rate 20%), and a flexible permanent magnet was manufactured by single pole magnetization as shown in FIG. Magnetization was performed at 2.0 T using the magnetizing apparatus.

The molding process of the precursor using polyurethane A is as follows. 85.2 parts by weight of EXCENOL3030 (manufactured by Asahi Glass Co., Ltd., polyoxypropylene glycol, OH number 56, functional group number 3) was placed in a reaction vessel, and dehydration under reduced pressure was performed for 1 hour while stirring. Thereafter, the inside of the reaction vessel was purged with nitrogen. Next, 14.8 parts by weight of Cosmonate T-80 (Mitsui Chemicals, toluene diisocyanate, 2,4 bodies = 80%) was added to the reaction vessel, and the temperature in the reaction vessel was maintained at 80 ° C. for 5 hours. By reacting, an isocyanate-terminated prepolymer (NCO% = 3.58%) was synthesized. In a mixed solution of 189.8 parts by weight of EXCENOL3030 (Asahi Glass, polyoxypropylene glycol) and 0.26 parts by weight of dibutyltin dilaurate (manufactured by Nacalai Tesque), MQP-14-12 (manufactured by Moricorp Magnequench, Neodymium) A filler dispersion was prepared by adding 676.2 parts by weight of a filler having an average particle size of 50 μm. This filler dispersion is degassed under reduced pressure, and 100 parts by weight of the prepolymer that has been degassed under reduced pressure is added, mixed and defoamed with a rotation / revolution mixer (Sinky), and a magnetic filler-containing reaction. A liquid was prepared. This reaction solution was dropped on a polyethylene terephthalate film subjected to a release treatment, and the thickness was adjusted to 2.0 mm with a doctor blade. This was allowed to stand at room temperature for 15 minutes and subjected to uneven distribution treatment, and then cured at 80 ° C. for 15 hours to form a precursor in which the magnetic filler was unevenly distributed in the thickness direction of the polymer matrix layer.

Example 2
SE1740 was used as the matrix material for the polymer matrix layer, and a precursor in which the magnetic filler was unevenly distributed in the thickness direction of the polymer matrix layer was molded. When a magnetic field was applied to the precursor, the polymer matrix layer was compressed (compression rate 20%), and a flexible permanent magnet was manufactured by single pole magnetization as shown in FIG. Magnetization was performed at 2.0 T using the magnetizing apparatus.

Example 3
As a matrix material to be a polymer matrix layer, an in-house made polyurethane elastomer (“polyurethane B”) described later was used, and a precursor in which magnetic fillers were unevenly distributed in the thickness direction of the polymer matrix layer was molded. When a magnetic field was applied to the precursor, the polymer matrix layer was compressed (compression rate 20%), and a flexible permanent magnet was manufactured by single pole magnetization as shown in FIG. Magnetization was performed at 2.0 T using the magnetizing apparatus.

The molding process of the precursor using polyurethane B is as follows. An isocyanate-terminated prepolymer was synthesized in the same manner as polyurethane A. A mixed solution of 106.8 parts by weight of EXCENOL3030 (manufactured by Asahi Glass Co., Ltd., polyoxypropylene glycol) and 0.19 parts by weight of dibutyltin dilaurate (manufactured by Nacalai Tesque) is mixed with MQP-14-12 (manufactured by Moricoop Magnequench, Neodymium) A filler dispersion was prepared by adding 482.4 parts by weight of a filler having an average particle size of 50 μm. This filler dispersion was degassed under reduced pressure, and 100.0 parts by weight of the prepolymer degassed under reduced pressure was added, mixed and defoamed with a rotating / revolving mixer (Sinky), containing a magnetic filler. A reaction solution was prepared. This reaction solution was dropped on a polyethylene terephthalate film subjected to a release treatment, and the thickness was adjusted to 2.0 mm with a doctor blade. This was allowed to stand at room temperature for 15 minutes and subjected to uneven distribution treatment, and then cured at 80 ° C. for 15 hours to form a precursor in which the magnetic filler was unevenly distributed in the thickness direction of the polymer matrix layer.

Examples 4-6
A flexible permanent magnet was manufactured under the same conditions as in Example 2 except that the compressibility when applying a magnetic field to the precursor was varied.

For each example magnet, the filler uneven distribution rate, elastic modulus, surface magnetic flux density, and magnetic flux density change were measured by the following methods. The measurement results are shown in Table 1. 10 to 17 are graphs showing the measurement results of the respective surface magnetic flux densities. The horizontal axis of the graph is the radial position of the magnet, and 5 mm and 25 mm correspond to the end positions, respectively.

[Filler uneven distribution ratio]
Using a scanning electron microscope-energy dispersive X-ray analyzer (SEM-EDS) (SEM: S-3500N manufactured by Hitachi High-Technologies Corporation, EDS: EMAX model 7021-H manufactured by Horiba, Ltd.), acceleration voltage 25 kV, degree of vacuum Under the conditions of 50 Pa and WD 15 mm, the cross section of the magnet was observed 50 times, and the entire area in the thickness direction of the cross section and two regions that were divided into two in the thickness direction were subjected to elemental analysis. The abundance of Fe element was determined, and the ratio of the abundance in a region where the magnetic filler was relatively large to the abundance in the entire region was calculated as the filler uneven distribution rate.

[Elastic modulus]
A compression test was performed using Autograph AG-X (manufactured by Shimadzu Corporation) at room temperature at a compression rate of 0.1 mm / min. As the test piece, a right cylindrical flexible permanent magnet having a thickness of 2 mm and a diameter of 10 mm was used. The compression modulus was obtained from the stress value at 24 to 26% strain.

[Surface magnetic flux density]
The surface magnetic flux density at a position 2 mm away from the magnetic pole face of a flexible permanent magnet having a diameter of 20 mm and a thickness of 2 mm was measured. The magnetic pole face is an N pole face, and when the magnetic filler is unevenly distributed, it is the surface of the first layer composed of a region on one side where the magnetic filler is relatively small. A magnet analyzer (MTS manufactured by IMS) was used for the measurement. The surface magnetic flux density at the center of the magnetic pole surface is the highest value within a range of 6 mm in diameter centered on the central position in the radial direction of the magnetic pole surface, and the surface magnetic flux density at the end of the magnetic pole surface is The highest value was set within a range of 3 mm from the radial end position of the magnetic pole surface toward the center position.

[Magnetic flux density change]
A flexible permanent magnet having a diameter of 20 mm and a thickness of 2 mm is affixed to one surface of the stainless steel plate, and the center of the sensor faces the central portion of the magnetic pole surface of the magnet so that the Hall element (Asahi Kasei) is the detector. Electronics-equipped EQ-432L) is affixed to the other side of the stainless steel plate, and pressure is applied to the magnet using a 50 mm x 50 mm surface indenter, and the magnetic flux density at 20% strain at 22.5% strain The change of was measured. The larger the numerical value, the better the detection sensitivity.

In Comparative Examples 1 and 2, since the surface magnetic flux density at the center portion is lower than the end portion of the magnetic pole surface, the change in magnetic flux density is relatively small, and it is evaluated that the detection sensitivity is low. On the other hand, in each of Examples 1 to 6, since the surface magnetic flux density at the central portion is higher than the end portion of the magnetic pole surface, the magnetic flux density change is relatively large, and the detection sensitivity is improved. I understand that.

DESCRIPTION OF SYMBOLS 1 Flexible permanent magnet 2 Magnetic filler 3 Polymer matrix layer 4 Detector 5 Deformation detection sensor 6 Sealed secondary battery 10 Precursor 31 First layer 32 Second layer

Claims (10)

1. In a method for producing a flexible permanent magnet having a magnetic filler and a polymer matrix layer containing the magnetic filler dispersed therein, the polymer matrix layer forming a sheet is deformed by applying an external force, and the polymer A method of manufacturing a flexible permanent magnet, wherein a magnetic field is applied in a state where a matrix layer is deformed, and thereby a surface magnetic flux density at a central portion is made higher than an end portion of a magnetic pole surface.
2. 2. The flexible permanent magnet according to claim 1, wherein the polymer matrix layer is deformed by applying a compressive force in the thickness direction as the external force, and the magnetic field is applied in the thickness direction of the deformed polymer matrix layer. Production method.
3. The method for producing a flexible permanent magnet according to claim 2, wherein the compressive force is applied so as to obtain a compression ratio of 5 to 50%.
4. The method for producing a flexible permanent magnet according to any one of claims 1 to 3, wherein the magnetic filler is unevenly distributed in the thickness direction of the polymer matrix layer.
5. A flexible permanent magnet having a magnetic filler and a polymer matrix layer containing the magnetic filler dispersed therein, comprising magnetic pole surfaces having different polarities on both surfaces of the polymer matrix layer forming a sheet, A flexible permanent magnet having a surface magnetic flux density at a central portion higher than that of an end portion of a surface.
6. The flexible permanent magnet according to claim 5, having an elastic modulus of 0.5 to 40 MPa.
7. The flexible permanent magnet according to claim 5 or 6, wherein the magnetic filler is unevenly distributed in the thickness direction of the polymer matrix layer.
8. A deformation detection sensor comprising the flexible permanent magnet according to any one of claims 5 to 7 and a detector configured to be able to detect a change in a magnetic field accompanying deformation of the polymer matrix layer.
9. A flexible permanent magnet according to any one of claims 5 to 7 is attached to a detection object, and the change in the magnetic field accompanying the deformation of the polymer matrix layer is detected by a detector, thereby detecting the detection object. A deformation detection method for detecting deformation of a body.
10. The deformation detection method according to claim 9, wherein the object to be detected is a sealed secondary battery.

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