Photoresin containing soft magnetic materials and methods for shaping photoresin containing soft magnetic materials on a substrate.

Abstract

The invention relates to a ratio of soft magnetic material to be mixed into an adhesive (resin) and the amount of soft magnetic material discharged on a substrate, which is not specified. If this ratio and amount are low, the magnetic attraction will be weak. If this ratio and amount are high, the viscosity of the adhesive after mixing will increase, resulting in poor discharge on the substrate and reduced elasticity after solidification. The range of the ratio of soft magnetic material powder (e.g., iron) to be mixed into the adhesive is specified. By specifying this ratio, it is possible to create sufficient magnetic attraction and prevent the reduction in elasticity of the adhesive after solidification. Furthermore, a method for shaping photoresist resins containing soft magnetic materials on a substrate can be proposed, in which, when discharging an adhesive made of photoresist resin mixed with soft magnetic materials on a substrate, a portion of the adhesive adhering to the substrate can be solidified, and then the discharge window can be separated from the substrate, thereby preventing deformation of the discharged adhesive. Thus, the discharge amount can be appropriately managed based on checking the distance between the discharged resins.

Description

Soft magnetic material-containing photocurable resin and method for forming the soft magnetic material-containing photocurable resin on a substrate.

[0001] The present invention relates to a photocurable resin containing a soft magnetic material and a method for forming the photocurable resin containing a soft magnetic material onto a substrate.

[0002] Automotive seat cushions are generally manufactured by mold molding, where polyurethane raw materials are injected into a mold and foamed within the mold. A surface covering is then attached to the surface that comes into contact with the human body. During the mold molding process, a fabric-like base material is placed in the mold beforehand so that it faces the underside of the foam pad. The resulting foam pad has polyurethane formed on this base material, with the polyurethane being reinforced by the base material. In subsequent seat assembly processes, the seat cushion, formed by attaching the surface covering to the foam pad, becomes easier to handle as it is less prone to damage.

[0003] During the aforementioned mold molding process, a mold shaped to mimic the shape of the seat cushion on the side where the base material will be placed, and a mold shaped to correspond to the surface side of the finished seat cushion are used in combination. The base material is attached to the mold so as to cover it. Soft magnetic materials that have been pre-attached to several locations on the base material are attracted by magnets embedded in the mold, and the base material is fixed to the mold during the foam pad formation process in which polyurethane or the like is foamed.

[0004] Patent Document 1 discloses a technique for integrating a foamed synthetic resin pad body (foam pad in the present invention) and an insert member (base material in the present invention) such as reinforcing fabric, used in seats and furniture such as those installed in vehicles, ships, and aircraft, by attaching a magnetic layer to the surface of a pre-molded insert member and having it attracted to a magnet placed in the molding die, which is a molding die, thereby fixing the insert member to the molding die.

[0005] Japanese Patent Publication No. 2016-036463

[0006] Patent Document 1 describes a method for forming a magnetic layer by applying an adhesive mixed with powders such as iron and nickel to a stamp surface, transferring it to an insert member, and then curing it. Various synthetic polymer compounds such as synthetic rubber and other resins, as well as photocurable resins, can be used as the adhesive. However, the mixing ratio of iron and nickel and the amount applied to the insert member are not disclosed, and there are no specifications for the characteristics of the magnet attached to the mold (magnetic flux density, etc.). If the mixing ratio of metal powders such as iron is low, the attraction force to the magnet is weak, and the insert member cannot be fixed to the mold unless the number of magnets and magnetic layers on the mold is increased. If the mixing ratio of metal powders is increased too much, the viscosity of the adhesive becomes high, resulting in poor discharge and transfer properties, and a decrease in elasticity after curing. Therefore, it was necessary to find an appropriate range for the mixing ratio of metal powders and to apply an appropriate amount to the reinforcing cloth.

[0007] Therefore, the present invention aims to provide a range of ratios for a soft magnetic material powder (e.g., iron) to be mixed into the resin of an adhesive, which can provide a magnetic layer (magnetic layer in Patent Document 1; obtained by mixing the resin and the soft magnetic material powder (hereinafter sometimes simply referred to as soft magnetic material) and curing it, the same applies hereinafter) that also ensures elasticity, and which can provide a range of ratios that allow the substrate on which the magnetic layer is formed to be sufficiently attracted to a magnet. Furthermore, the present invention aims to provide a method for forming a soft magnetic material-containing photocurable resin on a substrate, which can prevent the discharge shape of the resin from collapsing when discharging an adhesive made of a photocurable resin mixed with a soft magnetic material (hereinafter referred to as a soft magnetic material-containing photocurable resin) onto a reinforcing cloth (hereinafter referred to as a substrate) by curing a portion of the adhesive attached to the substrate before separating the discharge window from the substrate, and which can appropriately control the discharge amount based on an inspection of the distance between the discharged resins.

[0008] To solve the above problems, the present invention provides the following. As the first invention, a photocurable resin containing a soft magnetic material is provided, comprising a polymerization raw material containing a urethane oligomer having at least an acrylic group and / or an epoxy group, a crosslinking agent, a photoreaction initiator, and a soft magnetic material powder, wherein the soft magnetic material powder is 50% or more and 75% or less by weight.

[0009] As a second invention, a photocurable resin containing a soft magnetic material is provided, based on the first invention, wherein the crosslinking agent is 2-hydroxypropyl methacrylate.

[0010] As a third invention, a photocurable resin containing a soft magnetic material is provided, which is based on either the first or second invention and further contains a reaction-promoting additive.

[0011] As a fourth invention, a soft magnetic material-containing photocurable resin is provided, based on any one of the first to third inventions, wherein the viscosity of the polymerization raw material contained in the resin before photocuring is 1,000 to 500,000 millipascal seconds at a rotation speed of 0.6 rpm or less of a B-type viscometer.

[0012] As the fifth invention, a photocurable resin containing a soft magnetic material is provided, based on any one of the first to fourth inventions, wherein the viscosity of the polymerization raw material contained in the resin before photocuring is, as measured by a B-type rotational viscometer, 40,000 millipascal seconds or more and 44,000 millipascal seconds or less at 6 rpm and 30,000 millipascal seconds or more and 34,000 millipascal seconds or less at 12 rpm.

[0013] As the sixth invention, a method for forming a soft magnetic material-containing photocurable resin on a substrate is provided, comprising: a filling step of filling a cylinder with a soft magnetic material-containing photocurable resin according to any one of the first to fifth inventions; a dispensing step of dispensing the filled soft magnetic material-containing photocurable resin from a plurality of dispensing windows provided at the tip of the cylinder to the extent that it penetrates to the back surface of the substrate; a spacing inspection step of inspecting the spacing between the dispensed soft magnetic material-containing photocurable resins; and a quality determination step of determining whether the dispensing is good or bad based on the spacing inspection step.

[0014] The seventh invention is based on the sixth invention, wherein the base material is a nonwoven fabric made of polyester fibers, with a thickness in the range of 0.5 mm to 50 mm, and a basis weight of 50 g / m². ２ More than 200g / m ２ The present invention provides a method for forming a nonwoven fabric containing a soft magnetic material and a photocurable resin onto a substrate, within the following ranges.

[0015] As the eighth invention, the present invention provides a method for forming a soft magnetic material-containing photocurable resin on a substrate, based on either the sixth or seventh invention, comprising: an irradiation step of irradiating the back side of the soft magnetic material-containing photocurable resin discharged onto the substrate with a curing ray after the discharge step; a retraction step of retracting the discharge window above the soft magnetic material-containing photocurable resin after the irradiation step; and a curing step of irradiating the soft magnetic material-containing photocurable resin discharged onto the substrate with a curing ray from above and / or below after the retraction step.

[0016] As the ninth invention, a method for forming a soft magnetic material-containing photocurable resin onto a substrate is provided, based on any one of the sixth to eighth inventions, wherein the weight of the soft magnetic material-containing photocurable resin discharged onto the substrate in the discharge step is in the range of 0.10 grams to 0.25 grams.

[0017] With the above configuration, the present invention provides a method for forming a soft magnetic material-containing photocurable resin on a substrate. This method allows for obtaining a magnetic layer by curing the resin after mixing in a soft magnetic material powder (e.g., iron) that also maintains elasticity, and provides a range of ratios in which the substrate on which the magnetic layer is formed and a magnet can be sufficiently attracted. Furthermore, when dispensing the soft magnetic material-containing photocurable resin onto a substrate, curing a portion of the adhesive attached to the substrate before separating the dispensing window from the substrate prevents the dispensing shape of the resin from collapsing, and allows for appropriate control of the dispensing amount based on an inspection of the distance between the dispensed resins.

[0018] Diagram illustrating the structure of an automobile seat Graph showing the weight ratio (%) of iron powder and viscosity in the soft magnetic material-containing photocurable resin of the present invention Diagram illustrating the manufacturing process of a seat insert and seat cushion for an automobile seat Flow diagram illustrating the magnetic material mounting process of Embodiment 6 of the present invention Examples of multiple discharge windows at the tip of the cylinder of the present invention Schematic cross-sectional diagram 1 after the soft magnetic material-containing photocurable resin of the present invention is discharged onto the substrate surface Schematic cross-sectional diagram 2 after the soft magnetic material-containing photocurable resin of the present invention is discharged onto the substrate surface Photograph and schematic diagram of an example of the resin pattern after the soft magnetic material-containing photocurable resin of the present invention is discharged onto the substrate surface A schematic diagram showing an example of a pattern void inspection location for the soft magnetic material-containing photocurable resin of the present invention. Flow diagram of the magnetic material mounting process in Embodiment 7 of the present invention. An explanatory diagram of the magnetic material mounting process in Embodiment 8 of the present invention. A flow diagram of the magnetic material mounting process in Embodiment 9 of the present invention. A flow diagram of the magnetic material mounting process in Embodiment 9 of the present invention. A graph of the iron powder weight ratio (%) and adsorption force (N) in the soft magnetic material-containing photocurable resin of the present invention. A graph of the iron powder weight ratio (%) and relative permeability in the soft magnetic material-containing photocurable resin of the present invention. A graph of the iron powder weight ratio (%) and aperture ratio in the soft magnetic material-containing photocurable resin of the present invention.

[0019] The following describes embodiments of the present invention. However, the present invention is not limited to these embodiments and can be implemented in various forms without departing from its essence. Reference numerals in the description of the invention's structure and in the diagrams thereof are denoted by four-digit numbers, where the first two digits represent the drawing number and the last two digits represent the number uniquely assigned to each part.

[0020] This specification describes, as an example, a case in which a substrate made of a nonwoven fabric to which a magnetic layer obtained by curing the soft magnetic material-containing photocurable resin and the method for forming the soft magnetic material-containing photocurable resin on a substrate of the present invention is attached is used as a substrate for a foam pad that serves as a seat cushion for an automobile.

[0021] Furthermore, the use of this invention is not limited to automobile seats. It can be applied to seats in vehicles other than automobiles, such as motorcycles, transport equipment such as forklifts, construction machinery such as power shovels, agricultural machinery such as combine harvesters, passenger transport vehicles such as trains and buses, ships, aircraft, and spacecraft, as well as chairs such as sofas, game chairs, and office chairs, and wheelchair seats. In addition to seats, it can also be applied to cushioning materials for helmets, soundproofing materials, and heat insulating materials. Alternatively, the resin of the present invention and the nonwoven fabric on which a magnetic layer has been attached using the method of forming the resin on the base material of the present invention can be applied as a base material alone without forming a foam pad to automobile soundproofing and vibration damping insulators (dash insulators, floor insulators, door insulators, etc.).

[0022] Furthermore, the magnetic material can be used not only to attach a magnetic layer to a nonwoven fabric, woven fabric, or film-like sheet as a base material for magnet attraction, but also as an ink or coating. Information (e.g., object identification information, object attribute information (material, place of production, manufacturer, manufacturing date, manufacturing lot, product name, model number, owner, warranty period, expiration date, etc.), shipping source and destination information, etc.) can be included in a predetermined pattern formed with the ink or coating using the soft magnetic material-containing photocurable resin of the present invention on the surface of an object such as a sheet, card, or box. For example, a barcode or two-dimensional code can be formed on the surface of a product or packaging box using an ink using the resin of the present invention. Furthermore, if the formed barcode or two-dimensional code is covered with an ink of the same color as the ink, it becomes unreadable by visual inspection or optical readers. By concealing the location where the barcode or two-dimensional code is formed and using a magnetic reader for reading, the possibility of others reading the contents of the code can be reduced.

[0023] Alternatively, by applying a paint using the resin of the present invention to the walls of buildings, posters can be attached with magnets, magnetic hooks can be attached, and various objects can be attached using magnets. When attaching an iron plate to a wall, it is necessary to reinforce the wall to withstand the weight of the iron plate, but the soft magnetic material-containing photocurable resin layer formed by applying a paint using the resin of the present invention is not as heavy as an iron plate, eliminating the need to reinforce the wall. Furthermore, the present invention, such as a paint containing a powder of a magnetized soft magnetic material, such as ferrite, which has high coercivity even though it is a soft magnetic material, can be used as a coating material for structures made of soft magnetic materials, such as automobile bodies (stainless steel with some soft magnetism remaining), bridges, and steel structural parts such as storage tanks. In this case, the paint is less likely to peel off from the surface of the structure, resulting in a highly durable coating.

[0024] <Seats: Structure> The structure of a car seat will be explained using Figure 1. Although car seats are divided into front seats and rear seats in terms of shape, their structure is almost the same and is composed of three main parts. As shown in Figure 1, these three parts are the seat surface (0101) (also called the seat cushion) on which a person sits, the backrest (0102) (also called the seat back) on which a person leans their back, and the headrest (0103) attached to the top of the backrest.

[0025] As shown in Figure 1, the seat consists of a pipe frame (0104) made of metal pipes and springs, to which a foam pad (0106) formed directly on a base material (0105) using foamed urethane resin or the like is attached. The foam pad (0106) is then covered with a surface material (0107) by adhesive or other means.

[0026] On the left of FIG. 1, a partial cross-section of the backrest of FIG. 1 is shown within a circle. A base material (0105) formed using a non-woven fabric, a woven fabric, a film-shaped sheet, or the like is disposed between the seat pipe frame (0104) and a foam pad (0106) made of a foamed urethane resin or the like, preventing the foam pad (0106) from rubbing against the pipe frame (0104) and wearing out due to the shaking of the vehicle during driving or the movement of the passenger's body. A skin (0107) is attached to the surface of the foam pad (0106) that comes into contact with the passenger, contributing to an improvement in the durability and appearance of the foam pad (0106).

[0027] <Embodiment 1 - Overview>Mainly, for Claim 1, the soft magnetic material-containing photocurable resin used to form a magnetic layer on a base material such as a non-woven fabric includes a polymerization raw material containing at least a urethane-based oligomer having an acrylic group or / and an epoxy group, a cross-linking agent, a photo-reaction initiator, and soft magnetic powder, and is configured such that the soft magnetic powder is 50% or more and 75% or less by weight ratio.

[0028] <Embodiment 1 - Photocurable Resin>The "photocurable resin" requires the "polymerization raw material" and the "photo-reaction initiator", and can further include a "cross-linking agent", a "reaction acceleration additive", a "filler", a "stabilizer", and the like.

[0029] <Embodiment 1 Photocurable Resin: Mechanism of Curing> When light of a predetermined wavelength is applied to the "photocurable resin", radicals or cations are generated from the "photoinitiator" corresponding to the "raw materials for polymerization". The generated radicals or cations react with the acrylic groups or epoxy groups in the molecules of the raw materials for polymerization, respectively, cleaving the C=C double bond of the acrylic group and forming a polymerization bond with a similar position in other raw material molecules for polymerization, or opening the ring of the epoxy group and forming a polymerization bond with a similar position. The "crosslinking agent" has acrylic groups or epoxy groups, etc., similar to the raw materials for polymerization, and the polymerization reaction becomes possible due to the radicals or cations generated from the photoinitiator, and binds to the cleaved or ring-opened positions in the raw material molecules for polymerization, linking the raw materials for polymerization together to form a three-dimensional network-like polymerization structure. The "reaction acceleration additive" enhances the efficiency of the photoinitiator and makes the curing reaction proceed faster and more efficiently. The "filler" can reduce the amount of resin used by mixing it with the resin. Also, by adding the filler, shrinkage and expansion of the resin can be reduced. The "stabilizer" is added for thermal stabilization and prevention of yellowing and cracking due to light.

[0030] <Embodiment 1 Photocurable Resin: Raw Materials for Polymerization> The "raw materials for polymerization" form the main skeleton of the photocurable resin after curing. The raw materials for polymerization are monomers or / and oligomers. Known ultraviolet-curable acrylate resins having an acrylic group (e.g., urethane acrylate, polyester acrylate, methyl acrylate, ethyl acrylate, butyl acrylate, etc.), methacrylic resins having a methacrylic group in which H in the acrylic group is replaced by CH ３ can be used, such as polymethacrylate, polymethacrylic acid ester, etc., photocurable epoxy resins, vinyl ester resins, epoxy acrylate, etc.

[0031] <Embodiment 1 Photocurable Resin: Photoreaction Initiator> The "photoreaction initiator" receives curing light (e.g., ultraviolet light or visible light in a specific wavelength range) and generates and releases radicals or cations from its molecules for reaction with the polymerization raw materials. If the polymerization raw materials used are acrylate-based, a photoreaction initiator for acrylate-based resins is used. If the polymerization raw materials used are epoxy-based, a photoreaction initiator for epoxy-based resins is used.

[0032] Photoinitiators for acrylate resins (e.g., benzophenone-based, acetophenone-based, benzoin ether-based, thioxanthone-based) generate radicals when exposed to ultraviolet light, which react with the C=C bond of the acrylate to polymerize. Photoinitiators for epoxy resins (e.g., sulfonium salt-based, such as diphenylsulfonium salt, iodonium salt-based, such as triphenyliodonium salt) generate cations (acids) when exposed to ultraviolet light, which react with the epoxy group to polymerize.

[0033] <Embodiment 1 Photocurable Resin: Crosslinking Agent> A "crosslinking agent" is added to connect the molecules of the polymerization raw materials and create a three-dimensional network structure, thereby improving the degree of curing, robustness, or durability of the resin. When using polymerization raw materials having acrylic groups, 2-hydroxypropyl methacrylate is used as the crosslinking agent, and when using polymerization raw materials having epoxy groups, polyisocyanate is used. The specific names of substances used as crosslinking agents will be explained in Embodiment 2 below.

[0034] <Embodiment 1 Photocurable Resin: Reaction-Promoting Additive> The "reaction-promoting additive" promotes the reaction in which the photoinitiator generates and releases radicals and cations. For example, it absorbs light at wavelengths other than those absorbed by the photoinitiator and transfers energy to the photoinitiator at a distance of 10 nm or less (Förster mechanism), or it directly transfers energy by exchanging excited electrons in the reaction-promoting additive with electrons in the photoinitiator (Dexter mechanism). The photoinitiator molecules that receive the transferred energy generate and release active species (radicals or cations). Alternatively, the reaction-promoting additive receives light of the same and / or different wavelengths as the photoinitiator and generates and releases active species (radicals or cations) of the same type as the photoinitiator. In this way, the polymerization of the polymerization raw materials is promoted by increasing the amount of active species generated and released.

[0035] When monomers and / or oligomers having an acrylic group are used as polymerization raw materials, triphenylamine (TPA) or dimethylamine (DMA) can be used as reaction-accelerating additives. Furthermore, when monomers and / or oligomers having an epoxy group are used as polymerization raw materials, methyldiethanolamine (MDEA) or dimethylamine (DMA) can be used as reaction-accelerating additives. Specific names of substances used as reaction-accelerating additives will be explained in Embodiment 3 below.

[0036] <Embodiment 1: Photocurable Resin: Curing Conditions> When curing a photocurable resin, use curing light suitable for the selected resin (e.g., ultraviolet light, UVA (wavelength 315 to 400 nm), visible light exceeding 400 nm and 420 nm or less, etc.) and apply the required integrated light amount (mJ / cm²). ２ ) Irradiate. This accumulated light quantity is the sum of the light quantities calculated as "light quantity" × "time". The unit of the accumulated light quantity required to cure the resin per unit area is mJ / cm as described above. ２Therefore, among acrylate resins that react quickly to light, it is preferable to use urethane acrylate oligomers, which are particularly elastic after curing, as the polymerization raw material. For photocurable resins using the urethane acrylate oligomer as the polymerization raw material, UVA (or visible light exceeding 400 nm and not exceeding 420 nm) is generally used as the curing light, with an integrated light intensity of 1000 to 3000 mJ / cm². ２ When irradiated, curing progresses within a few seconds. If a light source with low light intensity is used, the required cumulative light intensity will not be reached in a short time, thus extending the irradiation time required for curing.

[0037] In this specification, ultraviolet-curable resins are described as an example of photocurable resins, but similar effects can be obtained using resins that cure with other wavelengths of light, such as visible light (the same applies to other embodiments). To adjust the wavelength of light for curing, a photoreaction initiator is prepared, and a photoreaction initiator that generates radicals and / or cations at the desired wavelength is selected.

[0038] The photocurable resin preferably has a glass transition temperature and / or melting point of 150°C or higher. The magnetic layer formed on the substrate using the resin of this embodiment of the present invention is placed near where the foaming reaction of a resin, such as foamed urethane, occurs during the formation of a foam pad for a seat cushion, or when forming a foamed material for heat insulation or soundproofing. For example, the foaming of foamed urethane can reach temperatures of 60°C to 150°C. If the magnetic layer is exposed to such temperatures and melts, the photocurable resin may adhere to the mold and contaminate the substrate that is set next. Therefore, a resin that does not melt at the temperatures during the foaming reaction of the resin is preferable.

[0039] <Embodiment 1: Soft Magnetic Powder> In the present invention, a magnetic layer is formed on a substrate made of a nonwoven fabric or the like. As the soft magnetic powder to be added to the photocurable resin as described above, powders of iron, nickel, cobalt, etc. can be used. Iron powder, which is readily available and inexpensive, is the most preferred soft magnetic powder to use. In the embodiments described herein, iron powder is described as an example of soft magnetic powder, but similar effects can be obtained by using other known soft magnetic materials such as nickel and cobalt.

[0040] <Embodiment 1 Weight Ratio of Soft Magnetic Powder> In the soft magnetic material-containing photocurable resin of the present invention, the weight ratio of soft magnetic powder to the photocurable resin is 50 wt% or more and 75 wt% or less in weight percent (hereinafter referred to as wt%). The range of the weight ratio of the soft magnetic powder was determined by evaluating and studying the viscosity of the mixture obtained by mixing iron powder with the photocurable resin, which is readily available as an example of soft magnetic powder, the appearance after curing, the magnetic attraction force with magnets, the B-H characteristics, the relative permeability, and the aperture ratio in the mixture (definition will be described later).

[0041] <Embodiment 1 Iron Powder Weight Ratio: Viscosity> The upper limit of the iron powder weight ratio for photocurable resins containing soft magnetic materials will be explained first, based on the viscosity evaluation results of photocurable resins mixed with iron powder. Figure 2 shows the results of the viscosity of the resin (Type B viscometer, 0.6 rpm) on the vertical axis (logarithmic scale), with the iron powder weight ratio (%) in the photocurable resin containing soft magnetic materials on the horizontal axis (linear display). In Figure 2, black circles indicate the viscosity for each iron powder weight ratio (%). The measured viscosity values ​​were 86670 mPa·s at 55 wt% iron powder weight ratio, 93330 mPa·s at 60 wt%, 100000 mPa·s at 65 wt%, 206700 mPa·s at 70 wt%, and 273300 mPa·s at 75 wt% iron powder weight ratio. Furthermore, the exponential approximation line for viscosity data at iron powder weight ratios of 55 to 75 wt%, indicated by the black circles, is shown as a dotted line. The viscosity at 50 wt%, extrapolated based on the approximation line, was 53483 mPa·s.

[0042] Next, we will explain the lower limit of the iron powder weight ratio. When a photocurable resin containing a soft magnetic material is dispensed onto a vertical surface, or when the resin is held in a droplet form at the tip of a syringe pointed downwards, the viscosity of the resin generally needs to be 5000 mPa·s or higher to prevent it from dripping downwards. The tendency to drip also depends on the thickness (or height) of the resin after dispensing. In this invention, the lower limit of the viscosity of the photocurable resin containing a soft magnetic material before curing was set to 5000 mPa·s or higher. The upper limit was set to 1,000,000 mPa·s, which is the upper limit for mixing. Preferably, it is 10,000 mPa·s or higher for less dripping, and 700,000 mPa·s or lower for mass production. Since it was not possible to specify the range of the mixing weight ratio of iron powder (soft magnetic material powder) from the viewpoint of viscosity, the range will be determined by other evaluations.

[0043] <Embodiment 1 Iron Powder Weight Ratio: Appearance After Curing> Explanation of Iron Powder Weight Ratio Upper Limit of 75 wt% or Less: When a photocurable resin mixed with iron powder is cured, if the iron powder weight ratio exceeds 75 wt%, it cannot retain elasticity after curing and becomes prone to cracking when bent. For use as a base material for foam pads for automobile seats, it is unsuitable for magnetic layers where bending forces may be applied when attaching to a mold for forming the foam pad. Similarly, it is unsuitable for applications where bending forces are applied to the magnetic layer after curing (such as heat insulating materials and sound insulating materials with bendable parts, or covers formed on a soft sheet-like base material that are folded and stored when not in use). For this reason, the iron powder weight ratio was set to 75 wt% or less.

[0044] <Embodiment 1 Iron Powder Weight Ratio: Adsorption with Magnets> Explanation of the Lower Limit of Iron Powder Weight Ratio of 50 wt% or More The lower limit of the iron powder weight ratio will be explained based on the evaluation results of adsorption with magnets. The adsorption of the resin cured from the soft magnetic material-containing photocurable resin of the present invention to a magnet is performed in order to fix and hold the sheet-like substrate from which the resin of the present invention has been extruded with a magnet. Therefore, if the iron powder weight ratio in the resin is too low, the adsorption force with the magnet will be insufficient. The lower limit of the iron powder weight ratio necessary to hold the substrate was investigated. As a specific example of evaluation, the adsorption force for holding the nonwoven fabric substrate was evaluated using a magnet for substrate attachment (surface magnetic flux density 0.30 to 0.44 T) installed in a mold for forming foam pads. The adsorption force must be at least 1.5 N or more. This is because the largest substrate for automobile seats, the seat surface of a rear two-seater seat, has an area of ​​approximately 1.4 m × 0.5 m = 0.7 m². As the base material for the rear seat cushion, if a nonwoven fabric with a basis weight of 200 g / m² (within the range of 50 g / m² to 200 g / m² as described in Embodiment 7 below) is used, an adsorption force of 1.5 N is sufficient to hold 0.75 m² (weighing 150 g) of nonwoven fabric, thus securing the nonwoven fabric for the rear seat cushion. Ten samples were prepared for each condition with varying iron powder weight ratios, and the adsorption force was measured. Due to variations in adsorption force measurement and the possibility of forces attempting to shift the nonwoven fabric during foam expansion of urethane, etc., during foam pad formation, a margin of safety was ensured, and 2.4 N or higher was used as the criterion for determining the quality of the conditions during evaluation, rather than 1.5 N or higher. Reducing the number of magnetic layers attached to the base material as much as possible reduces the man-hours and material costs required for attachment.

[0045] In evaluating the adsorption with magnets, three samples with iron powder weight ratios of 55 wt%, 60 wt%, and 65 wt% were evaluated (see Figure 9). For evaluation, samples were prepared by extruding 0.125 g of soft magnetic material-containing photocurable resin of each iron powder weight ratio into a 16 mm diameter circle on the surface of a nonwoven fabric substrate and curing it. From the evaluation results for the three iron powder weight ratio conditions, a linear approximation was used as the approximation line based on the three results. When the iron powder weight ratio is increased above 65 wt%, the amount of soft magnetic material powder contributing to adsorption to the magnet increases, so it is thought that the adsorption force becomes stronger than that of the 65 wt% sample, as shown by the approximation line, or that the adsorption force saturates with respect to the increase in iron powder weight ratio. For 65 wt% and above, this was confirmed by extrapolation using the aforementioned approximation line. For less than 55 wt%, it is thought that the adsorption force decreases in proportion to the decrease in iron powder weight ratio, so this was also confirmed by extrapolation using the aforementioned approximation line. At 50 wt% or more, the adsorption capacity was calculated to be approximately 2.4 N, and since it was expected that a margin of safety could be obtained over the standard of 1.5 N, the lower limit of the iron powder weight ratio was set at 50 wt%. Preferably, it is 55 wt% or more.

[0046] <Embodiment 1 Iron Powder Weight Ratio: B-H Characteristics, Relative Permeability> Explanation of the Upper Limit of Iron Powder Weight Ratio Below 75 wt% The upper limit of the iron powder weight ratio will be explained using the evaluation results of relative permeability obtained from the B-H characteristics of samples with varying iron powder weight ratios. Samples (50 wt%, 60 wt%, 70 wt%) were prepared by mixing iron powder with a photocurable resin at different weight ratios as a soft magnetic material, and the B-H characteristics were measured. This was done to determine an appropriate iron powder weight ratio from the magnetic properties of the photocurable resin containing the soft magnetic material. The relative permeability was determined from the slope of the B-H characteristic graph for each sample. A graph (Figure 10) was created with the iron powder weight ratio (wt%) on the horizontal axis and relative permeability on the vertical axis, and an approximation line was added as a dotted line. When preparing the sample for measurement, it was not possible to create a sample shape for B-H characteristic measurement at 75 wt%, so the 75 wt% value was obtained by extrapolation using the approximation line. The relative permeability for each iron powder weight ratio, based on the measured values, was 2.65 for 50 wt%, 3.68 for 60 wt%, and 4.06 for 70 wt%. The relative permeability at 75 wt% (for reference), extrapolated from the approximation line, was 4.16. The variation in these relative permeabilities was ±10%, with ±5% being preferable.

[0047] When iron powder is mixed into a resin, the magnetic permeability of the resin changes depending on the weight ratio of the iron powder. Generally, the relative permeability of a resin alone, without soft magnetic materials, is close to 1. When iron powder is mixed into a resin, the high responsiveness (magnetization) of the iron powder to a magnetic field is reflected in the properties of the entire material, so the magnetic resistance of the mixture (photocurable resin containing soft magnetic materials) decreases and the relative permeability increases. Magnetic permeability is an indicator of how easily a magnetic field passes through a material. When the weight ratio of iron powder increases to 50 to 60 wt%, the distance between dispersed iron powder particles in the resin becomes closer than at low weight ratios, making it easier for the iron powder particles to magnetically bond. As a result, a path (magnetic path) is formed through which the magnetic field continuously passes between the iron powder particles, and the magnetic permeability increases. Furthermore, when the weight ratio of iron powder is increased to a very high level, such as 75 wt% or more, the distance between iron powder particles decreases, so the magnetic interaction between iron powder particles strengthens, and sometimes contact may occur. Thus, at high weight ratios, the interaction between iron powder particles becomes dominant, the magnetization of individual iron powder particles tends to saturate, and the magnetic field becomes less permeable due to the dense arrangement of iron powder, resulting in a slowdown in the increase of relative permeability. Therefore, as the weight ratio of iron powder increases, the relative permeability of the mixed resin increases, resulting in the outcome shown in Figure 10.

[0048] As mentioned above, the relative permeability increases up to about 70 wt%, and beyond 75 wt%, the increase in relative permeability slows down even if the weight ratio of iron powder, which is a soft magnetic material, is increased. Therefore, the upper limit of the iron powder weight ratio is 75 wt% or less, and preferably 70 wt% or less.

[0049] <Embodiment 1 Iron Powder Weight Ratio: Aperture Ratio> Explanation of the Upper Limit of 75 wt% or Less for Iron Powder Weight Ratio The upper limit for the iron powder weight ratio will be explained based on the results of a simple calculation of the rate at which light reaches the surface opposite to the irradiation surface when curing light is irradiated onto a resin mixed with iron powder. When curing light is irradiated onto a photocurable resin containing a soft magnetic material, the rate at which the curing light is not blocked by the iron powder mixed into the photocurable resin as a soft magnetic material powder and passes through to the resin surface opposite to the incident surface of the light was simply estimated as an area ratio. Iron powder that is readily available as a soft magnetic material powder generally has triiron tetroxide (Fe) on its surface. ３ O ４is formed. Magnetite has a low reflectivity of UVA, which is a common light source for curing photocurable resins. As a means of verifying the validity of the iron powder weight ratio, the area ratio was estimated as the ratio of the area where no iron powder particles are arranged in the thickness direction of the resin through which light passes in the cured resin to the projected area of the cured resin (hereinafter referred to as the aperture ratio).

[0050] <Embodiment 1 Iron powder weight ratio: Aperture ratio: Prerequisites> For the model studied, the specific gravity of the photocurable resin was 1.07, the average particle size of the iron powder was 58 μm, and the density of iron was 7.87 g / cm ３ , the resin discharge amounts of 0.125 g and 0.25 g onto the non-woven fabric surface, and the numerical values of a circle with a discharge area diameter of 16 mm (2.011 cm ２ ) were used.

[0051] <Embodiment 1 Iron powder weight ratio: Aperture ratio: Estimation procedure> As the estimation procedure, for each of the iron powder weight ratios of 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, and 75 wt%, the volume of 1 g of the soft magnetic material-containing photocurable resin was determined, and the density of the resin and the number density (number / cm ３ ) of the iron powder in the resin were calculated respectively. The thickness of the disk when the resin of each iron powder weight ratio was discharged in a disk shape with a bottom diameter of 16 mm was obtained from the formula: disk thickness = discharge amount (0.1 g, 0.125 g or 0.25 g) / the density of the resin / the bottom area of the disk. The integer part of the quotient obtained by dividing the obtained thickness by the diameter of the iron powder of 58 μm was taken as the number of layers in which the iron powder was arranged in the thickness direction. For ease of calculation, the estimation was performed by limiting to the area of 1 cm square (area 1 cm ２ ) in the disk of the discharged resin.

[0052] <Embodiment 1 Iron powder weight ratio: Aperture ratio: Calculation method of aperture ratio> In a 1 cm square, frames divided into a grid with a side length of 58 μm of the iron powder diameter for each section can be arranged in 172×172 frames. The 172×172 frames overlap in the thickness direction by the number of layers calculated above. Using this total number of frames (the product of the number of frames per layer and the number of layers), the number density calculated for each weight ratio × (1 cm ２Divide the number of iron powder particles obtained by (x × thickness of the extruded disk) by the probability that an iron powder particle will be placed in each frame. Use a random number for each frame, and if the result is greater than or equal to the aforementioned probability, an iron powder particle will be placed. For example, if the frames within one layer are represented by x, y coordinates and the layers are represented by z coordinates, and there are three layers (z = 1, 2, 3) in thickness, (x ｎ , y ｍ , 1) from (x ｎ , y ｍ If iron powder is not placed in all three layers of 3), then (x ｎ , y ｍ Leave the box for (x ｎ , y ｍ , 1) from (x ｎ , y ｍ ,3) If iron powder is placed in even one layer, (x ｎ , y ｍ Frames marked with an asterisk () are counted as containing iron powder. Taking the thickness direction into account in this way, the number of empty frames in a 172 x 172 frame where no iron powder is placed was divided by the number of frames per layer (= 172 x 172) to determine the aperture ratio. Frames in the aforementioned thickness direction where no iron powder is placed are frames through which the curing light can be transmitted.

[0053] <Embodiment 1 Iron Powder Weight Ratio: Opening Ratio: Results> Figure 11 shows the estimated opening ratio for each iron powder weight ratio. The graph shows three lines: discharge volume of 0.25 g (thin solid line), 0.125 g (thick solid line), and 0.1 g (thin dotted line). The number of layers in the thickness direction is 0.25 g < 0.125 g < 0.1 g, so the opening ratio is higher in the above order, with 0.25 g having the lowest opening ratio. Discharge volumes of 0.125 g and 0.1 g have a high opening ratio of 11% or more in the range of iron powder weight ratio from 50 wt% to 65 wt%. Even at an iron powder weight ratio of 75 wt%, the opening ratio is 4% or more. On the other hand, with a discharge volume of 0.25 g, the opening ratio is 1.2% or more in the range of iron powder weight ratio from 50 wt% to 65 wt%. At a discharge rate of 0.25 g and an iron powder weight ratio of 75 wt%, the aperture ratio is low at approximately 0.3%, but not so low that it can be considered zero. Calculations show that at 80 wt%, the aperture ratio drops another order of magnitude to 0.02%. Therefore, from the viewpoint of aperture ratio, the upper limit for the iron powder weight ratio is 75 wt%. When the aperture ratio is low as described above, it is preferable to irradiate the discharged resin with curing light from both the back surface (nonwoven fabric side) and the front surface, as in the embodiment described later. Alternatively, the cumulative light intensity of the curing light irradiation can be increased.

[0054] The estimated aperture ratio indicates that the lower the iron powder weight ratio, the higher the aperture ratio, allowing the curing light to reach the opposite side of the irradiated surface more easily. The upper limit for the iron powder weight ratio is 75 wt% or less, with 70 wt% or less being preferable. Although the estimate was made by assuming that the iron powder is arranged in a grid pattern, in reality, a hexagonal close-packed arrangement is also possible, so the aperture ratio may be higher than the above estimate.

[0055] <Embodiment 1 Iron Powder Weight Ratio: Results of Study> Based on the evaluations described above, the upper and lower limits of the iron powder weight ratio were examined, and it was found that the range of soft magnetic material powder to be included in the soft magnetic material-containing photocurable resin is 50 wt% or more and 75 wt% or less. Preferably, it is 55 wt% or more and 70 wt% or less, and most preferably 65 wt%. In the weight ratio study, iron powder was used as an example, but similar effects can be obtained by using soft magnetic material other than iron (e.g., nickel, cobalt, etc.).

[0056] <Effects of Embodiment 1> In Embodiment 1, by using a soft magnetic material-containing photocurable resin, the iron powder content is 50 wt% or more and 75 wt% or less by weight, a magnetic layer with excellent magnetic attraction to magnets and elasticity after curing can be obtained.

[0057] <Summary of Embodiment 2> The soft magnetic material-containing photocurable resin of Embodiment 2 is mainly based on Embodiment 1, and uses 2-hydroxypropyl methacrylate as the crosslinking agent for the soft magnetic material-containing photocurable resin.

[0058] <Embodiment 2 Crosslinking Agent> The "crosslinking agent" is used to bond the monomers and / or oligomers of the polymerization raw materials to form a three-dimensional network structure, thereby improving the degree of curing and durability of the resin. By adding functional monomers or oligomers as a crosslinking agent, the polymerized molecules of the polymerization raw materials are further linked together to form a three-dimensional network structure. 2-hydroxypropyl methacrylate has a methacrylic group, and within that methacrylic group, it has a C=C bond similar to that of an acrylic group. In the polymerization reaction, radicals react with the C=C of the methacrylic group of 2-hydroxypropyl methacrylate, crosslinking with the molecules of the urethane oligomer. In the soft magnetic material-containing photocurable resin of Embodiment 1, using 2-hydroxypropyl methacrylate as a crosslinking agent for a resin having an acrylic group-containing urethane acrylate oligomer as a polymerization raw material is preferable because it has the effects described below.

[0059] Using 2-hydroxypropyl methacrylate (hereinafter referred to as MHP) provides the following effects: (1) High crosslinking efficiency: MHP has high crosslinking efficiency and can form a porous structure. It functions as a lightweight insulating material and can support the insulating effect of urethane. (2) Durability: Crosslinked polymers have high durability and improved mechanical strength. (3) Transparency: Polymers using MHP have high transparency and are suitable for optical applications. Therefore, since ultraviolet light transmittance is also high, the polymer that has already cured does not interfere with ultraviolet light transmission as crosslinking gradually progresses by irradiation with curing light including ultraviolet light. (4) Chemical stability: MHP is chemically stable and has excellent weather resistance and chemical resistance. Due to these characteristics, it is an excellent crosslinking agent to be used in the present invention.

[0060] As for the "crosslinking agent," if the polymerization raw material has an acrylic group, methacrylic acid-based agents (e.g., 2-hydroxypropyl methacrylate, ethylenediamine dimethacrylate (DMAEMA), diglycidyl methacrylate (GDMA), etc.) are preferred.

[0061] When the raw material for polymerization has an epoxy group, the crosslinking agent is preferably a polyisocyanate (e.g., diisocyanate trimellitic acid) or an amine (e.g., diethylaminoethanol (DEAE), triethanolamine).

[0062] <Effects of Embodiment 2> By using 2-hydroxypropyl methacrylate as a crosslinking agent for the soft magnetic material-containing photocurable resin of Embodiment 2, polymerized molecules can be further linked together to form a three-dimensional network structure.

[0063] <Summary of Embodiment 3> The soft magnetic material-containing photocurable resin of Embodiment 3 is mainly based on either Embodiment 1 or Embodiment 2, and is configured to further contain a reaction-promoting additive.

[0064] <Embodiment 3 Reaction-Promoting Additive> The "reaction-promoting additive" has the function of further promoting the action of the photoinitiator when exposed to light such as ultraviolet light. When the polymerization raw material of the soft magnetic material-containing photocurable resin contains an acrylic group, the photoinitiator helps generate radicals for polymerization and promotes polymerization. When the polymerization raw material of the soft magnetic material-containing photocurable resin contains an epoxy group, the photoinitiator helps generate cations to open the epoxy group and polymerize the epoxy groups together, thereby promoting polymerization.

[0065] <Embodiment 3 Reaction-accelerating additives: Specific examples> When monomers and / or oligomers having acrylic groups are used as polymerization raw materials, the following can be used as reaction-accelerating additives. (1) Amines Triphenylamine (TPA) and dimethylamine (DMA) are reaction-accelerating additives that promote the photopolymerization of acrylate resins. These amines work to efficiently advance the polymerization reaction of acrylic groups. (2) Phosphines Triphenylphosphine (TPP) and trimethylphosphine may promote the reaction more efficiently than amines in UV curing. These are used together with photoinitiators to improve the reaction rate. (3) Suburea compounds Polyurethane acrylate (PUA) is used to enhance the curing reaction of acrylate resins and improve durability after curing. (4) Redox reaction agents Peroxides (e.g., benzoyl peroxide) enhance the effect of photoinitiators through redox reactions in acrylate resins and promote the curing reaction.

[0066] <Embodiment 3 Reaction-accelerating additives: Specific examples> When monomers and / or oligomers having epoxy groups are used as polymerization raw materials, the following can be used as reaction-accelerating additives. (1) Amines Methyldiethanolamine (MDEA) and dimethylamine (DMA) accelerate the reaction with epoxy groups and promote the curing reaction. These amines react directly with epoxy groups to promote curing. (2) Peroxides Benzoyl peroxide (BPO) and methyl ethyl ketone peroxide (MEK Peroxide) are used to accelerate the photocuring of epoxy resins. These peroxides decompose under ultraviolet light, generating free radicals that accelerate the reaction with epoxy groups. (3) Redox reagents Ascorbic acid (vitamin C) and naphthalene are used when redox reactions are utilized to accelerate the curing of epoxy resins. These agents help the curing reaction proceed quickly by reducing oxides. (4) Metal complexes Titanate esters and chromium complexes are used to accelerate the ultraviolet curing reaction of epoxy resins. These metal complexes are activated by ultraviolet light and play a role in accelerating the reaction of epoxy groups.

[0067] <Effects of Embodiment 3> The soft magnetic material-containing photocurable resin of Embodiment 3 contains a reaction-accelerating additive, which allows the curing reaction to proceed rapidly when exposed to curing light.

[0068] <Summary of Embodiment 4> The soft magnetic material-containing photocurable resin of Embodiment 4 is mainly based on any one of Embodiments 1 to 3, and is configured such that the viscosity of the polymerization raw material contained in the resin before photocuring is 1,000 to 500,000 millipascal seconds at a rotation speed of 0.6 rpm or less of a B-type viscometer.

[0069] <Embodiment 4 Viscosity of Polymerization Raw Materials> When soft magnetic materials such as iron powder are mixed in, the viscosity increases, so the viscosity of the polymerization raw materials contained in the soft magnetic material-containing photocurable resin before photocuring is also specified. The viscosity of the photocurable resin before mixing in the soft magnetic material is almost synonymous with the viscosity of the polymerization raw materials. This is because, while other additives such as crosslinking agents, photoreaction initiators, and reaction-accelerating additives are generally liquids, the monomers and oligomers that make up the polymerization raw materials have long molecular chains and large molecular weights, resulting in high viscosity. Consequently, the influence of the polymerization raw materials on the viscosity of the soft magnetic material-containing photocurable resin before photocuring is dominant. If the viscosity of the resin before mixing in the soft magnetic material is high, the viscosity after mixing in the soft magnetic material will also be high, and if you try to mix in soft magnetic material powder at a high weight ratio, the viscosity will become even higher, making mixing difficult. If the viscosity of the polymerization raw material is in the range of 1,000 to 500,000 mPa·s at a rotation speed of 0.6 rpm or less on a Type B viscometer, then by mixing it with the soft magnetic powder in the weight ratio shown in Embodiment 1, a soft magnetic material-containing photocurable resin can be obtained in which the viscosity after mixing with the soft magnetic powder as described in Embodiment 1 is 5,000 to 1,000,000 mPa·s or higher. Furthermore, having such a high viscosity prevents dripping from the tip of the dispensing device when dispensing onto a substrate surface, for example, and allows movement to the next dispensing location without taking measures to prevent dripping after dispensing. Dripping after dispensing can also be prevented when dispensing onto a vertical wall surface.

[0070] <Effects of Embodiment 4> By mixing the photocurable resin containing the polymerization raw materials of Embodiment 4 with a soft magnetic material, the photocurable resin containing a soft magnetic material shown in Embodiment 1 can be obtained.

[0071] <Summary of Embodiment 5> The soft magnetic material-containing photocurable resin of Embodiment 5 is mainly based on any one of Embodiments 1 to 4, and is configured such that the viscosity of the polymerization raw material contained in the resin before photocuring is 40,000 millipascal seconds or more and 44,000 millipascal seconds or less at 6 rpm and 30,000 millipascal seconds or more and 34,000 millipascal seconds or less at 12 rpm, as measured by a B-type rotational viscometer.

[0072] For adhesives dispensed onto walls, there are applications where the viscosity must decrease when dispensed from the cylinder (when shear force is applied), and then increase after it has settled on the wall (after the shear force is released), making it less likely to drip. This change in viscosity is called thixotropy. Thixotropy is generally measured and compared using a ratio of viscosities measured with a B-type viscometer, for example (e.g., 6 rpm viscosity / 12 rpm viscosity).

[0073] <Embodiment 5: Thixotropy> "Thixotropy" is defined as "also called thixotropy. It is a type of abnormal viscosity. Simply stirring or shaking it changes a gel into a fluid sol, and if left standing, it returns to a gel. Hysteresis occurs in the viscosity-shear stress curve. It was named by Freundlich (HMF) and Peterfi (T.)." (Quoted from Iwanami Dictionary of Physics and Chemistry, 5th edition, Iwanami Shoten, p. 833). In other words, if subjected to continuous shear stress, the viscosity gradually decreases and it becomes liquid, but when left at rest, the viscosity gradually increases and it eventually becomes solid.

[0074] When the resin of the present invention is extruded onto a nonwoven fabric substrate, if the thixotropy is low, the shape of the extruded resin tends to collapse and spread out between the time of extrusion and the time of curing by light irradiation. Also, as in Embodiment 9 described later, if the soft magnetic material-containing photocurable resin is allowed to overflow from the extrusion window before the extrusion window is lowered toward the substrate surface, if the thixotropy is low, the resin extruded from the extrusion window may drip toward the substrate surface and adhere to places other than the desired location before the extrusion window itself approaches the substrate surface. Because of these problems, it is preferable to have a predetermined thixotropy. The polymerization raw material contained in the photocurable resin before mixing with the soft magnetic material powder is a polymerization raw material (i.e., photocurable resin) in which the viscosity of the polymerization raw material contained in the photocurable resin is measured by a B-type rotational viscometer to be 40,000 mPa·s or more and 44,000 mPa·s or less at 6 rpm and 30,000 mPa·s or more and 34,000 mPa·s or less at 12 rpm. Thus, by using a photocurable resin containing polymerization raw materials with a thixotropy greater than 40,000 mPa·s / 34,000 mPa·s = 1.176, it is possible to obtain a photocurable resin containing a soft magnetic material that is less likely to cause the aforementioned problems.

[0075] <Effects of Embodiment 5> By mixing a thixotropic photocurable resin containing the polymerization raw materials of Embodiment 5 with a soft magnetic material, a soft magnetic material-containing photocurable resin as shown in Embodiment 1 can be obtained, and when dispensing the soft magnetic material-containing photocurable resin onto a substrate, it is possible to prevent the resin from dripping onto the substrate surface before dispensing.

[0076] <Summary of Embodiment 6> A magnetic layer is formed on the surface of a substrate mainly using a soft magnetic material-containing photocurable resin according to any one of Embodiments 1 to 5 of Claim 6.

[0077] <Embodiment 6 Configuration> The method for forming a soft magnetic material-containing photocurable resin onto a substrate according to Embodiment 6 consists of a filling step, a dispensing step, a spacing inspection step, and a quality determination step. Before describing the formation method in detail, the manufacturing process of an automobile seat will be described first as an example of using the substrate.

[0078] <Embodiment 6: Seat Manufacturing Process> Figure 3 shows an example of an automobile seat. Figure 3 mainly describes the base material manufacturing process and the seat cushion manufacturing process related to the present invention. In the seat assembly process for assembling an automobile seat, seat cushions such as the backrest, seat surface, and headrest are attached to a pipe frame manufactured in a separate process not shown in Figure 3, and the seat is assembled. In this specification, "base material" refers to the component that was called an insert member in Patent Document 1, and is also called a seat insert. Nonwoven fabrics, woven fabrics, film-like sheets, etc., can be used as base materials. The following description will explain the case in which nonwoven fabric is used as the base material, but similar effects can be obtained by using other sheet-like components such as woven fabrics or film-like sheets other than nonwoven fabrics.

[0079] <Embodiment 6 Seat Manufacturing Process: Base Material Manufacturing Process: Role of the Base Material> A base material made of nonwoven fabric or the like is attached to the back side of the foam pad, which is made of foamed urethane or the like and forms the seat cushion of an automobile seat. The base material reinforces the foam pad, making it easier to handle during the seat assembly process. The base material is also useful after the automobile is completed. The back side of the foam pad is in contact with pipes and springs that make up the pipe frame, which is the skeleton of the seat, and rubs against the support members such as pipes and springs due to the shaking of the car while driving and the movement of the occupants' bodies, so a soft sponge-like foamed urethane resin alone would be easily damaged. The base material on the back side of the foam pad is attached as a reinforcing material to prevent the foam pad from being damaged by rubbing against support members such as the pipe frame.

[0080] <Embodiment 6 Seat Manufacturing Process: Nonwoven Fabric Preparation Process> The first step in the base material manufacturing process shown in Figure 3 is the nonwoven fabric preparation process. The nonwoven fabric to be used as material is prepared. It may be manufactured in the next step, or the nonwoven fabric may be purchased from another company.

[0081] <Embodiment 6 Seat Manufacturing Process: Nonwoven Fabric Preparation Process: Method for Manufacturing Nonwoven Fabric> As an example of raw materials for the base material, a method for manufacturing nonwoven fabric will be described. Nonwoven fabric can be manufactured by known manufacturing methods and materials. The fibers that serve as raw materials for the nonwoven fabric must not be altered by the exothermic temperature during the foaming reaction when forming a foam pad on the nonwoven fabric in a later process. For example, during the foaming reaction of foamed urethane, the temperature near the center reaches about 60 to 150°C. Therefore, it is preferable that the melting point or softening point of the fibers constituting the nonwoven fabric be 150°C to a sufficiently high 160°C or 180°C or higher. For example, known fibers such as polyester, polypropylene, acrylic, and nylon can be used. When the nonwoven fabric is used for automobile seats, it is more preferable to use flame-retardant materials or fibers that have been given flame retardancy. The nonwoven fabric is first formed by creating a fleece layer, which is an aggregate layer of fibers, and then interfiber bonding is performed to bond the fibers together. The fleece is formed by one of the known methods such as the dry method, wet method, or spunbond method. The formed fleece is bonded together using one of the known methods, such as needle punching, water entanglement, chemical bonding, or thermal bonding.

[0082] <Embodiment 6 Seat Manufacturing Process: Nonwoven Fabric Preparation Process: Nonwoven Fabric Specifications> The thickness of the nonwoven fabric is 1 mm to 5 mm. 1 mm to 3 mm is preferable, and 1.5 mm to 2.5 mm is more preferable. A certain thickness is necessary to ensure sufficient strength against friction with pipes and springs. If it becomes too thick, it becomes difficult to conform to the shape of the mold, so the above range is appropriate. The basis weight of the nonwoven fabric is 100 g / m when the thickness is 2 mm. ２ From 200g / m ２ Therefore, the density is 120 to 160 g / m². ２ This is preferable. If the basis weight is too small, the nonwoven fabric will have a coarse weave, resulting in weaker strength. When the soft magnetic material-containing photocurable resin described later is dispensed onto the nonwoven fabric surface, it may soak into the fabric too much and spread out, potentially weakening the magnetic attraction. If the basis weight is too large, the rigidity of the nonwoven fabric will be too high, making it difficult to conform to the shape of the mold. Therefore, the above range is appropriate.

[0083] Furthermore, the nonwoven fabric may be made by forming a single nonwoven fabric from one or more nonwoven fabrics of different specifications by bonding the fibers together using methods such as needle punching or water entanglement. For example, the nonwoven fabric layer with densely packed fibers and a high basis weight can be placed on the side that comes into contact with the pipe frame, and the nonwoven fabric layer with a low basis weight can be placed on the side that forms the foam pad. As a result, the nonwoven fabric layer with densely packed fibers is resistant to friction with the pipe frame, and the nonwoven fabric layer with a low basis weight allows the foam pad's raw material resin, such as polyurethane foam resin, to easily permeate, resulting in a nonwoven fabric with a strong bond between the nonwoven fabric and the foam pad.

[0084] <Embodiment 6 Seat Manufacturing Process: Base Material Manufacturing Process: Nonwoven Fabric Molding Process> In the second step of the base material manufacturing process shown in Figure 3, the "nonwoven fabric molding process," the nonwoven fabric is processed to take on a shape corresponding to the mold used to form the foam pad in a later process. The base material can be either a sewn type, in which the nonwoven fabric is cut and shaped to fit the aforementioned mold and sewn as needed, or a molded type, in which it is shaped by vacuum forming or press molding. In the latter molded type, for example, thermoplastic fibers are used to maintain the shape that conforms to the mold. The nonwoven fabric molding process, which is a manufacturing method for the molded type, has the following steps:

[0085] <Embodiment 6 Seat Manufacturing Process: Base Material Manufacturing Process: Nonwoven Fabric Molding Process: Mounting Step> The "mounting step" is the step of attaching the nonwoven fabric, which has been cut into a predetermined shape, to a mold. The mold used in this step has a shape that corresponds to the mold used to form the foam pad in a later process. In the example in Figure 3, the mold (0312) has many holes (0313), and in the next molding step, the nonwoven fabric is molded by vacuum suction.

[0086] <Embodiment 6 Seat Manufacturing Process: Substrate Manufacturing Process: Nonwoven Fabric Molding Process: Molding Step> The "molding step" is the step of molding the nonwoven fabric. In the example in Figure 3, molding is performed by vacuum adsorption as described above. Although not shown, for example, an airtight sheet or bag is placed over the nonwoven fabric and the mold. By exhausting the space enclosed by the sheet or bag, the nonwoven fabric is sandwiched between the sheet or bag and the mold and molded into the shape of the mold. If thermoplastic fibers are used, the nonwoven fabric is heated before molding.

[0087] <Embodiment 6 Seat manufacturing process: Substrate manufacturing process: Nonwoven fabric molding process: Removal step> The "removal step" is the step of removing the molded nonwoven fabric (0323) molded from the mold (0312). After removal, any excess parts are cut off as appropriate. The appearance of the molded nonwoven fabric may be inspected at the removal step. This prevents defective products from being sent to the next magnetic material attachment process and starting work.

[0088] <Embodiment 6 Seat Manufacturing Process: Substrate Manufacturing Process: Magnetic Material Attachment Process> Process relating to the present invention The "magnetic material attachment process" is a process of attaching a magnetic material to the molded nonwoven fabric so that it can be attracted to a magnet installed in the mold when it is attached to the mold used in the foam pad forming process of the next seat cushion manufacturing process. The method of forming a soft magnetic material-containing photocurable resin on a substrate of the present invention relates to this magnetic material attachment process, and will be described in detail after the seat manufacturing process is explained.

[0089] <Embodiment 6 Seat Manufacturing Process: Seat Cushion Manufacturing Process: Foam Pad Forming Process> The "foam pad forming process" is a process of forming a foam pad made of foamed urethane or the like on a nonwoven fabric after it has been molded as a seat cushion. The foam pad forming process consists of the following steps.

[0090] <Embodiment 6 Seat Manufacturing Process: Seat Cushion Manufacturing Process: Foam Pad Forming Process: Base Material Attachment Step> The "base material attachment step" is a process of attaching a base material (0305), which has a magnetic layer attached to a molded nonwoven fabric, to a mold 1 (0326). During attachment, the magnetic layer (0308), which is attached to a position corresponding to a magnet installed in the mold 1 (0326), is attracted to fix the base material to the mold 1 (0326). Molded base materials are molded using a mold that corresponds to the shape of the mold 1, and can be attached along the shape of the mold 1. In the case of sewn base materials, the ability to conform to uneven parts when fixing to the mold 1 is inferior to that of molded base materials.

[0091] <Embodiment 6 Seat Manufacturing Process: Seat Cushion Manufacturing Process: Foam Pad Forming Process: Mold Fitting Step> The "mold fitting step" is a process of combining one or more other molds with mold 1 (0326) to which the base material (0305) is attached. In the example described here, mold 1 and mold 2 are used in combination. Mold 1 and mold 2 are combined to form a closed space containing the base material.

[0092] <Embodiment 6 Seat Manufacturing Process: Seat Cushion Manufacturing Process: Foam Pad Forming Process: Resin Injection Foaming Step> The "resin injection foaming step" is a step in which the raw material for the foam pad is injected into the closed space surrounded by mold 1 (0326) and mold 2 (0327), and a foaming reaction is carried out to form a foam pad (0306) integrally with the base material (0305). Known materials such as urethane resin are used as the raw material for the foam pad. The raw material for the foam pad may be injected into either mold 1 or mold 2 immediately before combining mold 1 and mold 2 in the mold joining step.

[0093] <Embodiment 6 Seat Manufacturing Process: Seat Cushion Manufacturing Process: Foam Pad Forming Process: Removal Step> The "removal step" is the step of removing the mold 2 (0327) from the mold 1 (0326) and removing the formed foam pad (including the base material) from the mold 1 (0326). The foam pad removed from the mold is then finished by removing excess parts such as burrs and undergoes a visual inspection.

[0094] <Embodiment 6 Seat Manufacturing Process: Seat Cushion Manufacturing Process: Upholstery Attachment Process> The "upholstery attachment process" is the process of attaching the upholstery that will actually come into contact with the passenger's body to the foam pad formed on the base material. Adhesive is applied to the surface of the foam pad, and the upholstery is attached.

[0095] <Embodiment 6 Seat Manufacturing Process: Seat Assembly Process> The "seat assembly process" is the process of assembling a seat by attaching the backrest, seat surface, and headrest of the seat formed as described above to a pipe frame manufactured in a pipe frame manufacturing process not shown in Figure 3. The seat assembled in the seat assembly process is further attached to the automobile body in the automobile assembly process, completing the automobile.

[0096] <Embodiment 6 Description of Magnetic Material Attachment Process> Of the automobile seat manufacturing processes described above, the magnetic material attachment process using the present invention will be described in detail below. Figure 4 shows the steps of the magnetic material attachment process. The magnetic material attachment process consists of a filling step, a dispensing step, a spacing inspection step, and a quality determination step.

[0097] <Embodiment 6 Magnetic material mounting process: Filling step> The "filling step" is a step of filling the cylinder with a soft magnetic material-containing photocurable resin of any one of Embodiments 1 to 5.

[0098] Dispensing equipment having a cylinder for supplying resin can also be a cylinder with multiple discharge windows, or known methods such as screen printing or roller transfer can be used. This specification will describe an example using a cylinder with multiple discharge windows.

[0099] The mixing of soft magnetic material into the photocurable resin may be performed by the manufacturer of the photocurable resin, or the person performing the magnetic material attachment may purchase the resin and soft magnetic material and mix them. When mixing, sufficient stirring should be performed so that the soft magnetic material is uniformly dispersed in the resin, and care should be taken to ensure that no air bubbles remain in the resin. Furthermore, in the area where the resin is removed from the container purchased from the resin manufacturer and mixed or filled, and in the production line near the magnetic material attachment process, it is advisable to use an illumination source that excludes or attenuates wavelengths of light that contribute to curing for at least 8 or 12 hours, equivalent to one shift of the production line, until the curing reaction of the photocurable resin does not occur, and the increase in viscosity due to the curing reaction is acceptable. For example, yellow fluorescent lamps or yellow LEDs that cut wavelengths below 500 nm may be used. Note that the filling of the cylinder may be performed by the resin manufacturer or the manufacturer of the equipment that dispenses the soft magnetic material-containing photocurable resin, and the cylinder may be delivered to the person who dispenses the resin onto the substrate.

[0100] By using photocurable resins, the need for heating to cure soft magnetic material-containing resins, which was previously required using thermosetting resins, is eliminated. Since both heating and cooling processes are unnecessary, energy efficiency is improved. Furthermore, while thermosetting resins required curing times ranging from tens of minutes to several hours, photocurable resins cure in just a few seconds after light irradiation, thus shortening working time. Additionally, with conventional thermosetting resins, there is a risk of burns to workers, and workers may inhale solvents volatilized during heating or products released into the air due to the reaction. With photocurable resins, the resin itself does not contain solvents, eliminating the risk of inhaling solvents or reaction products during curing. Moreover, by covering the light source for curing and requiring workers to wear protective equipment, worker exposure can be easily prevented even if the light source is ultraviolet. These are the advantages obtained by using photocurable resins.

[0101] <Embodiment 6 Magnetic Material Mounting Process: Discharge Step> The "discharge step" is a step in which the filled soft magnetic material-containing photocurable resin is discharged from a plurality of discharge windows provided at the tip of the cylinder to the substrate until it penetrates to the back surface of the substrate. Figure 5 shows an example of a plurality of discharge windows provided at the tip of the cylinder. In the example in Figure 5, there is one hole in the center and a plurality of holes (φ1 mm) surrounding it in a double circular shape.

[0102] The reason for dispensing from multiple discharge windows is to easily form a magnetic layer over a desired large area on the substrate surface. When a large amount of resin is dispensed from a single discharge window, it has thickness, but it does not spread as easily on the substrate as when dispensed from multiple discharge windows, resulting in a smaller area being formed.

[0103] A cylinder filled with a soft magnetic material-containing photocurable resin is brought close to the surface of the substrate, and the soft magnetic material-containing photocurable resin is discharged from the discharge window on the surface of the cylinder facing the substrate surface (cylinder tip). The discharge amount is determined by the magnitude of the pressure applied to the soft magnetic material-containing photocurable resin inside the cylinder and the duration of pressure application. It is most preferable to discharge the resin to the extent that it penetrates the back surface of the substrate, but penetration to more than half the thickness of the substrate is also acceptable. Preferably, penetration to more than two-thirds the thickness of the substrate is preferred.

[0104] The surface of the substrate from which the soft magnetic material-containing photocurable resin is extruded may be the surface facing the mold when attached to the mold in the foam pad forming process, or it may be the surface further away from the mold. If the resin is extruded onto the surface facing the mold to form the magnetic layer, it can be placed closer to the magnet installed in the mold. Forming the magnetic layer on the surface facing the mold allows for a stronger attraction force between the magnet and the magnetic layer than forming it on the surface further away from the mold. If the magnetic layer is attached to the side far from the mold, the substrate may be sandwiched between the magnetic layer and the magnet during attraction, potentially causing distortion of the substrate surface near the magnetic layer. When the foam pad is removed from the mold after formation, the thickness of the substrate near the magnetic layer may return to its original state and bulge slightly, potentially causing a deviation from the desired shape.

[0105] <Embodiment 6 Magnetic material mounting process: Spacing inspection step> The "spacing inspection step" is a step of inspecting the spacing between adjacent soft magnetic material-containing photocurable resin patterns that have been discharged from adjacent discharge windows and adhered to the surface of the substrate.

[0106] After the dispensing step, the cylinder is moved away from the substrate. As the resin is dispensed from multiple dispensing windows of the cylinder shown in Figure 5, the soft magnetic material-containing photocurable resin adhering to the substrate surface has a pattern shape that reflects the arrangement of the dispensing windows. The spacing between adjacent resin patterns is measured. The spacing between the resins is determined by the distance between the dispensing window at the tip of the cylinder and the substrate surface, and the amount of resin dispensed. The schematic cross-sectional diagram in Figure 6 and the photograph and schematic diagram of the resin pattern after dispensing in Figure 8 are examples where the amount of resin dispensed is appropriate. There are mounds of dispensed resin in the areas corresponding to the dispensing windows, and the areas corresponding to the base of these mounds have seeped into and spread across the substrate surface. The schematic cross-sectional diagram in Figure 7 shows an example where the amount of resin dispensed was too much, causing the resin patterns dispensed from adjacent dispensing windows to connect.

[0107] An example of "spacing" will be explained using the schematic cross-sectional diagram of the resin pattern on the substrate surface after extrusion shown in Figure 9. It may be the distance d1 between adjacent resin patterns on the substrate surface where the resin does not adhere or penetrate (or whether such a substrate surface is visible between the resins), or it may be the horizontal distances d2 and d3 at predetermined percentages of the resin height (e.g., 90%, 10%). Alternatively, the spacing may be determined by measuring the half-width d4 of the extruded resin pattern. This is because the apex position of the extruded resin corresponds to the position of the extrusion window and is almost fixed regardless of the extrusion conditions. Therefore, instead of measuring the distance between resin patterns, the half-width of the extruded resin pattern (the width of the resin pattern at a height half the height from the substrate surface to the apex) can be measured and subtracted from the spacing of the extrusion windows to determine the distance between resin patterns. Distances like this example can be measured and inspected using a measuring instrument.

[0108] As an example of spacing, as shown in the schematic diagram on the right of Figure 8, the distance between adjacent soft magnetic material-containing photocurable resin patterns (which may also be the substrate surface where the resin does not adhere or penetrate) d1 or d1' may be measured, or the presence or absence of the gap may be visually inspected. In the case of a simple visual inspection, for example, when both d1 and d1', which are the gaps between adjacent resins as shown in the schematic diagram on the right of Figure 8, disappear, it is determined that the discharge amount is excessive and exceeds the upper limit. Conversely, when the gap d'' (which may also be the substrate surface where the resin does not adhere or penetrate) between the resin patterns discharged from the central discharge window and the discharge window immediately outside it is visible, it is determined that the discharge amount is insufficient and falls below the lower limit. If it is determined that the discharge amount exceeds the upper limit or falls below the lower limit, the system is operated to determine it as NG in the quality judgment step described later, for example.

[0109] The interval inspection step may be performed either before or after curing the extruded soft magnetic material-containing photocurable resin.

[0110] <Embodiment 6 Magnetic material mounting process: Quality determination step> The "quality determination step" is a step in which the quality of the ejection is determined by the interval inspection step.

[0111] In the spacing inspection step, if the distance between the soft magnetic material-containing photocurable resins extruded and adhering to the substrate surface is greater than a predetermined value, the extrusion amount will fall below the lower limit, resulting in insufficient magnetic force on the mold's magnet and potentially preventing the resin from being fixed to the mold. This is considered a defect and the extrusion was not performed properly. Conversely, if the extrusion amount is so large that there are no gaps and exceeds the upper limit, while sufficient for adhesion to the mold, the amount of light irradiation for curing (cumulative light dose) may be insufficient, potentially leaving uncured areas. Furthermore, extruding more than necessary increases manufacturing costs. For this reason, it is also considered a defect. The pass / fail judgment may be based on the numerical result of the spacing measurement, or it may be performed by visual inspection to check for gaps between adjacent extruded resin patterns as described above. When measuring the spacing in the former case, the measuring instrument may be configured to incorporate a judgment function and perform the measurement simultaneously. Alternatively, the presence or absence of gaps between resin patterns extruded onto the substrate surface can be determined by pattern recognition using artificial intelligence.

[0112] If the discharge volume falls below the lower limit, additional soft magnetic material-containing photocurable resin may be manually dispensed. If the discharge volume exceeds the upper limit, additional curing light may be applied, or a portion may be removed if it has not yet cured.

[0113] When performing a quality determination step after curing of the extruded soft magnetic material-containing photocurable resin, it is preferable to configure the process to include not only the determination based on the results of the interval inspection step, but also the external shape of the magnetic layer formed on the surface of the substrate after extrusion (shape, thickness distribution, presence or absence of cracks and chips, presence or absence of foreign matter, etc.).

[0114] <Effects of Embodiment 6> The method of forming a soft magnetic material-containing photocurable resin on a substrate according to Embodiment 6 allows for inspection of the spacing between the resin particles attached to the extruded substrate, enabling the determination of an appropriate extrusion amount and management of the extrusion step.

[0115] <Summary of Embodiment 7>Embodiment 7 mainly defines the specifications of the substrate (material, thickness, basis weight) to form a good magnetic layer by a soft magnetic material-containing photocurable resin discharged onto the surface of the substrate.

[0116] <Embodiment 7 Configuration> The base material of Embodiment 7, which is based on Embodiment 6, is a nonwoven fabric made of polyester fibers, and its material, thickness, and basis weight are configured as follows.

[0117] <Embodiment 7: Base Material> The "base material" of Embodiment 7, which is based on Embodiment 6, is a nonwoven fabric made of polyester fibers, with a thickness in the range of 0.5 mm to 50 mm, and a basis weight of 50 g / m². ２ More than 200g / m ２ This is a nonwoven fabric within the following range.

[0118] <Embodiment 7 Substrate: Nonwoven Fabric Material> When using an ultraviolet-curing resin that hardens with ultraviolet light as the photocurable resin contained in the soft magnetic material-containing photocurable resin, the substrate is preferably a nonwoven fabric made of polyester fibers. Polyester fibers are composed of polymers having aromatic rings, have a high molecular extinction coefficient for ultraviolet light, and have excellent ultraviolet shielding properties. Although it depends on the specifications of the fabric using polyester fibers, the transmittance of polyester fibers for UVA (wavelength 315 to 400 nm) is generally about 10 to 20%. Therefore, when light irradiation is performed from the back surface of the substrate as in Embodiment 8 described later, light does not reach the soft magnetic material-containing photocurable resin near the substrate surface or on the substrate surface more than necessary, thus preventing the resin on the substrate surface side from starting to harden.

[0119] <Embodiment 7 Base Material: Thickness of Nonwoven Fabric> The nonwoven fabric used as the base material has a thickness in the range of 0.5 mm to 50 mm. When used for automobile seats, the thickness is 1 to 5 mm, preferably 1 mm to 3 mm, and more preferably 1.5 mm to 2.5 mm. For automobile seats, a certain thickness is necessary to ensure sufficient strength. If it becomes too thick, it becomes difficult to conform to the shape of the mold used to form the foam pad, so the above range is appropriate. The thickness of the nonwoven fabric used as the base material for cushions with complex shapes such as automobile seats is within the above range, but if it is used for other purposes (for example, soundproofing material, heat insulating material, or doormats using nonwoven fabric alone with a magnetic layer), a thickness of 10 to 50 mm is appropriate.

[0120] <Embodiment 7 Base material: Basis weight of nonwoven fabric> The basis weight of the nonwoven fabric is 50 g / m when the thickness is 2 mm. ２ From 200g / m ２ Therefore, 100 g / m ２ From 200g / m ２ Preferably, 120 to 160 g / m ２This is preferable. If the basis weight is small while maintaining the same thickness, it becomes a coarse nonwoven fabric, resulting in weaker strength. If the basis weight is small, when a soft magnetic material-containing photocurable resin is dispensed onto the substrate surface, it may soak into the nonwoven fabric too much, reach the back surface of the substrate, and adhere to and contaminate the stage of the dispensing device on which the substrate is placed. Conversely, if the basis weight is too large, the rigidity of the nonwoven fabric becomes too high, making it difficult to conform to the shape of the mold, so the above range is appropriate. When used as a base material for foam pads for automobile seats, if the basis weight is too large, the gas permeability during foaming of urethane resin and other materials may be further reduced.

[0121] <Effects of Embodiment 7> By using the nonwoven fabric of Embodiment 7 as a base material, the soft magnetic material-containing photocurable resin can be effectively extruded onto the base material surface, forming a magnetic layer.

[0122] <Summary of Embodiment 8> The method for forming a soft magnetic material-containing photocurable resin on a substrate according to Embodiment 8, which is mainly based on either Embodiment 6 or Embodiment 7, is configured such that, after the discharge step, a curing light ray is irradiated from the back side of the discharged resin, and then the discharge window is retracted above the resin and the curing light ray is irradiated onto the resin.

[0123] <Embodiment 8 Configuration> A method for forming a soft magnetic material-containing photocurable resin on a substrate according to Embodiment 8, which is based on either Embodiment 6 or Embodiment 7, will be described using Figures 10 and 11. The forming method of Embodiment 8 is configured to include, in addition to the forming method of Embodiment 6, an irradiation step, a retraction step, and a curing step after the discharge step, as shown with an asterisk in Figure 10. Therefore, only the irradiation step, the retraction step, and the curing step will be described below. In the following description, the additional irradiation step, the retraction step, and the curing step are configured to be performed between the discharge step and the interval inspection step, but the curing step may be configured to be performed after the interval inspection step or the pass / fail judgment step. The same effect can be obtained in that case as well.

[0124] <Embodiment 8 Irradiation Step> The "irradiation step" is a step in which, after the discharge step, a curing light ray is irradiated from the back side of the soft magnetic material-containing photocurable resin discharged onto the substrate.

[0125] The leftmost figure in Figure 11 shows an example of the discharge step. A soft magnetic material-containing photocurable resin (1132) is discharged from the cylinder (1131) through the discharge window onto the surface of the substrate (1105). The center figure in Figure 11 shows an example of the irradiation step. UV light is irradiated from a UV-LED light source (1134) onto the back surface of the discharged resin through the substrate. In Figure 11, the stage (1133) where the cylinder (1131) and the substrate (1105) are in contact is missing, and the UV-LED light source (1134) is positioned there. A plate-shaped member that allows the curing light of the soft magnetic material-containing photocurable resin to pass through may be placed in the missing part of the stage. By positioning it at the same height as the stage surface in contact with the substrate, it is possible to prevent the substrate from bending significantly downward when the resin comes into contact with the substrate from the discharge window at the tip of the cylinder and a downward force is applied. When UVA is used as the curing light, and the resin is cured mainly with light of wavelengths around 365 nm to 385 nm, the plate-like member can be made of quartz glass or glass for flat panel displays such as liquid crystal panels, which have high transmittance from the aforementioned wavelengths to the visible light region. The same applies to the explanation using Figure 13 in Embodiment 9 described later.

[0126] When a soft magnetic material-containing photocurable resin is extruded onto a substrate and curing light is not irradiated from the back side, and the extrusion window is retracted vertically above the resin after the resin has been extruded onto the substrate surface, there was a problem in that the wettability or adhesion between the resin and the substrate surface was poor, and most of the extruded resin remained attached to the extrusion window and separated from the substrate surface. Therefore, conventionally, instead of retracting vertically, the window was moved slightly diagonally upward or horizontally before being retracted vertically upward to increase the contact area between the extruded resin and the substrate surface, preventing the resin from sticking to the extrusion window. This retraction method is like rubbing the resin extruded through multiple extrusion windows onto the substrate surface, and the gaps between the extruded resin particles are also filled with the rubbed resin. Therefore, it was not possible to inspect the extruded resin pattern to determine if the extruded amount was within the normal range. Instead, the only way to determine the extruded amount was to measure the cured resin after it had been cured using a ruler and a stylus step meter, which was not a simple procedure.

[0127] The curing light (e.g., ultraviolet light) irradiated from the back side of the resin discharged onto the substrate after the discharge step and before the discharge window is retracted is not for completely curing the resin, but rather to cure at least a portion of the resin that has penetrated the substrate or the resin near the substrate surface, thereby keeping the discharged resin on the substrate surface. By curing at least a portion of the resin that has penetrated or is in contact with the substrate, the resin can be kept attached to the discharge window and not separated from the substrate surface even when the discharge window is retracted vertically. In order to avoid distorting the shape of the discharged resin even when the discharge window is retracted vertically upward, the spacing of the resin corresponding to each discharge window can be measured in a later spacing inspection step.

[0128] The amount of curing light irradiated from the back during the irradiation step should be 10-20% of the total light amount required to completely cure the resin. Too much light will cause curing to begin on the surface side of the substrate. Too much light will cause the resin near the discharge window to begin curing, narrowing or blocking the opening of the discharge window. The above range is appropriate considering the transmittance of the nonwoven fabric and other materials that make up the substrate.

[0129] <Embodiment 8 Retraction Step> The "retraction step" is a step in which the discharge window is retracted above the soft magnetic material-containing photocurable resin after the irradiation step.

[0130] As described above, when the irradiation step was not performed conventionally, instead of retracting vertically, the discharge window was moved slightly diagonally upward or horizontally before being retracted vertically upward to increase the contact area between the discharged resin and the substrate surface, preventing it from sticking to the discharge window. By using a photocurable resin as the polymerization raw material and further including an irradiation step, the discharge window can be retracted upward without distorting the shape of the resin discharged onto the substrate surface (without changing the spacing of the resin in contact with the substrate). The most preferable direction of retraction is vertically upward from the location where the resin was discharged, which is close to the substrate surface.

[0131] <Embodiment 8 Curing Step> The "curing step" is a step in which a curing light ray is irradiated from above and / or below onto the soft magnetic material-containing photocurable resin that has been discharged onto the substrate after the retraction step. The rightmost figure in Figure 11 is an example of the curing step.

[0132] In the curing step, curing light is irradiated onto the substrate surface to completely cure the resin extruded onto it. The curing light varies depending on the type of photocurable resin used, but a typical example is the combination of a UV lamp or UV LED for ultraviolet curable resins. In the example shown in the right-hand figure of Figure 11, UV light is irradiated only from the surface side of the resin as curing light, but it is also possible to use only the UV LED light source, which is the light source for the curing light on the back side used in the irradiation step, or to irradiate from both sides to cure the resin.

[0133] Using both upper and lower curing light sources increases the amount of curing light irradiated per unit time, thus shortening the curing time. The curing time for light-curing resins is only a few seconds, which is significantly shorter than the processing time for thermosetting resins, which can range from several minutes to tens of minutes (or even several hours depending on the type of resin).

[0134] <Effects of Embodiment 8> The method of forming a soft magnetic material-containing photocurable resin on a substrate according to Embodiment 8 allows the discharge window to be separated from (retracted from) the substrate without having to apply the discharged soft magnetic material-containing photocurable resin. Furthermore, after retracting in this manner, the distance between the resins can be measured, and the discharge amount can be controlled.

[0135] <Summary of Embodiment 9> The method for forming a soft magnetic material-containing photocurable resin on a substrate according to Claim 9 further comprises an overflow pressing step in which, before curing the discharge window on the substrate, the tip of the cylinder is pressed against the substrate while the resin is overflowing from the discharge window.

[0136] <Embodiment 9 Configuration> Figures 12 and 13 show the forming method of Embodiment 9, which is based on the method of forming a soft magnetic material-containing photocurable resin on a substrate according to any one of Embodiments 6 to 8. The forming method of Embodiment 9 has an additional overflow pressing substep in the discharge step compared to the forming method of Embodiment 8. Since the steps other than the overflow pressing step have already been explained, only the overflow pressing step will be explained below. Similar effects can be obtained by using either Embodiment 6 or 7 as the basis.

[0137] <Embodiment 9: Overflow Pressing Substep> The "overflow pressing substep" is a substep in the discharge step in which, before lowering the discharge window onto the substrate, the soft magnetic material-containing photocurable resin is allowed to overflow from the discharge window, and then the tip of the cylinder is pressed against the substrate in that state.

[0138] Figure 12 shows a flow diagram illustrating the magnetic material attachment process of Embodiment 9, which is based on Embodiment 8 (the method for forming a soft magnetic material-containing photocurable resin on a substrate according to the present application). In the dispensing step, an overflow pressing step is performed.

[0139] Figure 13 is a schematic diagram illustrating each step. Five diagrams are arranged in a row. The leftmost diagram shows the state after the filling step is completed, the cylinder is set in the dispensing device, and the substrate (1305) is set on the stage of the dispensing device. Unlike Figure 11, the cylinder (1331) of the dispensing device has a UV-LED light source (1334) located above the substrate in the opening and closing lid at the tip of the case (1336) that encloses the cylinder (1331). Similar to Figure 11, Figure 13 also lacks the stage portion corresponding to the substrate that the dispensed resin comes into contact with. As described above, a plate-like member that transmits curing light, such as quartz glass, can be installed in this portion to prevent the substrate from bending downwards when the resin comes into contact with it.

[0140] The second figure from the left in Figure 13 shows the state after the dispensing step and the overflow pressing substep, in which the photocurable resin containing soft magnetic material is overflowed from the dispensing window. A predetermined amount is dispensed from the dispensing window and maintained with the photocurable resin containing soft magnetic material attached to the tip of the cylinder. If the viscosity and / or thixotropy is low, the dispensed resin will simply drip onto the surface of the substrate. With the lid at the tip of the cylinder (1331) case (1336) open, the tip of the cylinder is lowered below the lid and pressed against the surface of the substrate (see the figure in the center of Figure 13). By allowing a predetermined amount to overflow in advance, it is possible to prevent the dispensing amount from changing for each substrate due to variations in the distance to the cylinder tip caused by irregularities on the substrate surface.

[0141] The fourth figure from the left in Figure 13 shows the irradiation step. While the tip of the cylinder is pressed down, a curing ray (UV light (1335) in the example of Figure 13) is irradiated from the back surface of the discharged soft magnetic material-containing photocurable resin to cure at least a portion of the resin that has penetrated the nonwoven fabric substrate or is near the surface of the substrate.

[0142] The rightmost diagram in Figure 13 shows the curing step. The cylinder is retracted vertically above the resin, the lid at the tip of the cylinder is closed, and UV light for curing the resin is irradiated from the UV-LED installed on the lid. After the resin has cured, the spacing between the resins is inspected to determine if it is satisfactory, and the process is complete. In the curing step, it is also possible to configure the system to irradiate curing light from a lower UV-LED light source.

[0143] The cylinder for dispensing a soft magnetic material-containing photocurable resin shown in Figure 13 can be configured to open the lid at the front of the case by moving the cylinder to the dispensing position relative to the case. Conversely, it can be configured to close the lid at the front of the case by moving the cylinder upward relative to the case (away from the substrate surface). For example, a gear (pinion) can be installed on the rotation axis of the lid relative to the case so as to rotate in sync with the lid, and a rack (a flat plate with teeth of the same shape engraved at equal intervals) installed next to the cylinder can be engaged with it. With this configuration, the lid can be opened and closed by the vertical movement of the cylinder.

[0144] <Effects of Embodiment 9> The method of forming the soft magnetic material-containing photocurable resin onto a substrate according to Embodiment 9 makes it possible to keep the amount of resin discharged onto the substrate constant.

[0145] <Summary of Embodiment 10> In the dispensing step of the method for forming a soft magnetic material-containing photocurable resin onto a substrate according to Embodiment 10, the weight of the soft magnetic material-containing photocurable resin dispensed onto the substrate is in the range of 0.10 grams to 0.25 grams.

[0146] <Embodiment 10 Configuration> In the discharge step of the method for forming a soft magnetic material-containing photocurable resin onto a substrate according to Embodiment 10, which is based on any one of Embodiments 6 to 9, the weight of the soft magnetic material-containing photocurable resin discharged onto the substrate is in the range of 0.10 grams to 0.25 grams.

[0147] The weight of the resin dispensed onto the substrate in the dispensing step is between 0.1 grams and 0.25 grams. More preferably between 0.10 grams and 0.15 grams, and most preferably between 0.125 grams. If the dispensing amount is too small, the magnetic attraction force will be insufficient. If the dispensing amount is too large, when dispensed onto the substrate, adjacent resin patterns attached to the substrate surface may come into contact and merge, making it impossible to measure the distance between the resin patterns. With a dispensing amount of 0.25 grams or more, as estimated in Embodiment 1 regarding the aperture ratio, the transmission of curing light rays may be obstructed by the soft magnetic powder mixed with the resin, resulting in insufficient cumulative light required for curing inside the resin, and potentially insufficient curing. Therefore, the upper limit is 0.25 grams.

[0148] By setting the range as described above, the resin, after one dispensing step on the substrate surface, contains 0.05 grams to 0.1875 grams of soft magnetic material, forming a magnetic layer sufficient to be attracted to a magnet installed in the mold.

[0149] <Effects of Embodiment 10> In the method for forming a soft magnetic material-containing photocurable resin on a substrate according to Embodiment 10, by specifying the amount of resin to be discharged, it is possible to prevent the formed magnetic material layer from cracking or chipping when the substrate is bent, and furthermore, it can be carried out well when performing the overflow pressing substep.

[0150] <Effects> The present invention provides a method for forming a soft magnetic material-containing photocurable resin onto a substrate. This method allows for obtaining a magnetic layer with elasticity while maintaining elasticity, and provides a range of ratios in which the substrate on which the magnetic layer is formed and a magnet can be sufficiently attracted. Furthermore, when dispensing the soft magnetic material-containing photocurable resin onto a substrate, the dispensing shape of the resin can be prevented from collapsing by curing a portion of the adhesive attached to the substrate before the dispensing window is removed from the substrate. This method also allows for appropriate control of the dispensing amount based on an inspection of the distance between the dispensed resins.

[0151] Base material...1105 Cylinder...1131 Photocurable resin containing soft magnetic material...1132 Stage...1133 UV-LED light source...1134 UV light...1135

Claims

1. A photocurable resin containing soft magnetic material, comprising polymerization raw materials including a urethane oligomer having at least an acrylic group and / or epoxy group, a crosslinking agent, a photoreaction initiator, and soft magnetic material powder, wherein the soft magnetic material powder accounts for 50% or more and 75% or less by weight.

2. The soft magnetic material-containing photocurable resin according to claim 1, wherein the crosslinking agent is 2-hydroxypropyl methacrylate.

3. The soft magnetic material-containing photocurable resin according to claim 1 or claim 2, further containing a reaction-promoting additive.

4. The soft magnetic material-containing photocurable resin according to claim 1 or claim 2, wherein the viscosity of the polymerization raw material contained in the resin before photocuring is 1,000 to 500,000 millipascal seconds at a rotation speed of 0.6 rpm or less of a B-type viscometer.

5. The soft magnetic material-containing photocurable resin according to claim 4, wherein the viscosity of the polymerization raw material contained in the resin before photocuring is, as measured by a B-type rotational viscometer, 40,000 millipascal seconds or more and 44,000 millipascal seconds or less at 6 rpm and 30,000 millipascal seconds or more and 34,000 millipascal seconds or less at 12 rpm.

6. A method for forming a soft magnetic material-containing photocurable resin on a substrate, comprising: a filling step of filling a cylinder with the soft magnetic material-containing photocurable resin described in claim 1; a dispensing step of dispensing the filled soft magnetic material-containing photocurable resin from a plurality of dispensing windows provided at the tip of the cylinder to the extent that it penetrates to the back surface of the substrate; a spacing inspection step of inspecting the spacing between adjacent soft magnetic material-containing photocurable resin patterns that have been dispensed from adjacent dispensing windows and adhered to the surface of the substrate; and a quality determination step of determining whether the dispensing is good or bad based on the spacing inspection step.

7. The base material is a nonwoven fabric made of polyester fibers, with a thickness in the range of 0.5 mm to 50 mm, and a basis weight of 50 g / m². ２ More than 200g / m ２ A method for forming a soft magnetic material-containing photocurable resin onto a substrate according to claim 6, wherein the nonwoven fabric is within the following range.

8. A method for forming a soft magnetic material-containing photocurable resin on a substrate according to claim 6 or claim 7, further comprising: an irradiation step of irradiating the back surface of the soft magnetic material-containing photocurable resin discharged onto the substrate after the discharge step with a curing light; a retraction step of retracting the discharge window above the soft magnetic material-containing photocurable resin after the irradiation step; and a curing step of irradiating the soft magnetic material-containing photocurable resin discharged onto the substrate after the retraction step with a curing light from above and / or below.

9. The method for forming a soft magnetic material-containing photocurable resin on a substrate according to claim 6 or claim 7, wherein the discharge step further comprises a sub-step in which the soft magnetic material-containing photocurable resin is discharged from the discharge window before the discharge window is lowered onto the substrate, and then the tip of the cylinder is pressed against the substrate in that state.

10. The method for forming a soft magnetic material-containing photocurable resin on a substrate according to claim 6 or claim 7, wherein the weight of the soft magnetic material-containing photocurable resin discharged onto the substrate in the discharge step is in the range of 0.10 grams to 0.25 grams.

Images