Conductive laminate for heater, three-dimensionally molded heater, molded body heater, and manufacturing method thereof

Abstract

To provide a conductive composition for a conductive laminate for heaters, the conductive laminate being excellent in in-plane heating uniformity even after deformation to uneven surfaces or curved three-dimensional shapes due to tension and being capable of achieving high safety.SOLUTION: A conductive laminate for heaters includes a substrate including a thermoplastic resin, and a conductive layer. The conductive layer is a cured product of a conductive composition that contains a resin (A) and conductive fine particles (B). The elongation at break of the conductive layer in an atmosphere at 160°C is 90-300%, and the ratio (R80 / R40) of the rate of change (R80) in the resistance value of the conductive layer when an elongation rate is 80% to the rate of change (R40) in the resistance value of the conductive layer when an elongation rate is 40%, in an atmosphere at 160°C satisfies 5.0 or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a conductive laminate for heaters, a three-dimensional molded heater, a molded heater, and a method for producing the same. [Background technology]

[0002] Patent Document 1 discloses a specific conductive circuit integrated molded product having a resin molded product, a substrate embedded flush with one surface of the resin molded product, and a conductive circuit disposed between the resin molded product and the substrate. Patent Document 1 describes a method for manufacturing the conductive circuit integrated molded product, in which a substrate on which a specific conductive circuit is formed is placed on the cavity surface of an injection molding die, and then molten resin is injected to injection mold a resin molded body. In Patent Document 1, the conductive circuit is formed by etching a specific transparent thin metal film.

[0003] A printing method using conductive ink has been considered as a method for forming a conductive circuit to replace the etching method. The method of printing conductive ink does not require any complicated steps compared to the etching method, and can easily form a conductive circuit, improving productivity and reducing costs. For example, Patent Document 2 discloses a conductive ink containing specific conductive fine particles and a specific epoxy resin as a low-temperature processing type conductive ink capable of forming a high-definition conductive pattern by screen printing. It is said that the screen printing makes it possible to form a thick conductive pattern, and thus realizes low resistance of the conductive pattern.

[0004] Furthermore, Patent Document 3 discloses a method for manufacturing a decorative sheet capable of expressing a three-dimensional effect, in which a laminate having a printed layer printed in a pattern on a transparent resin layer and a laminate sheet having a decorative layer on a substrate are thermocompression-bonded to each other, thereby giving the decorative layer an uneven shape that follows the pattern of the printed layer.

[0005] Patent Document 4 discloses a method for obtaining a conductive circuit integrated molded product having a conductive circuit between a resin molded product and a substrate by thermoforming a molded film on which a conductive pattern has been formed by printing a conductive ink on a substrate, and integrating the molded film with a resin molded product. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2012-11691 A [Patent Document 2] JP 2011-252140 A [Patent Document 3] JP 2007-296848 A [Patent Document 4] JP 2019-189680 A Summary of the Invention [Problem to be solved by the invention]

[0007] According to the method of Patent Document 1, a conductor can be easily provided on the surface of a molded product. On the other hand, there is an increasing demand to form a conductive circuit, especially a heater circuit having a heat generating function, on the surface of a molded product having various shapes, such as a molded product having an uneven surface or a curved surface. In particular, high conductivity and uniformity of wiring resistance value while following a three-dimensional shape are required. When a substrate having a conductive layer is attached to the surface of such a molded product to form a conductive circuit, the substrate needs to be deformed to match the surface shape of the molded product. When the substrate is deformed, a large tensile deformation may occur partially in the conductive layer. The tensile deformation may cause breakage of the conductive layer, resulting in a problem of reduced conductivity. Furthermore, when forming a conductive circuit on such a molded product having an uneven surface or a curved surface, it is necessary to integrate the substrate and the molded product after or at the same time as deforming the substrate having the conductive layer. In this integration process, shear stress caused by the difference in deformability between the molded product and the substrate at high temperatures is applied to the conductive circuit, and the shear stress causes a decrease in the conductivity of the conductive layer, resulting in a problem of impaired heat generation as a heater circuit. In contrast, the method of Patent Document 4 provides the conductive ink material with resistance to the thermoforming process, and thus solves the problem of the decrease in conductivity due to shear stress at high temperatures. However, the conductive circuit formed on the surface of a three-dimensional molded product by the method of Patent Document 4 cannot suppress the occurrence of large differences in wiring resistance values ​​due to differences in the degree of deformation during the thermoforming process to form the three-dimensional shape, and the wiring resistance value may become locally excessive or excessively small, resulting in fatal uneven heat generation. In other words, when this molded product with integrated conductive circuit is used as a practical device under harsh conditions for a long period of time, in extreme cases, it may cause local overheating, threatening the safety of the device itself.

[0008] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a three-dimensional molded heater and molded body heater that incorporates a conductive layer that is prevented from significantly deteriorating due to tensile forces in the molding process and shear stresses at high temperatures, and that has excellent uniformity in heater wiring resistance value regardless of the degree of deformation after molding, and that has excellent in-plane uniformity in heat generation and high safety, as well as a method for producing the same. [Means for solving the problem]

[0009] The conductive laminate for a heater according to the present invention is A conductive laminate for a heater that is formed into a three-dimensional shape including an uneven surface or a three-dimensional curved surface, The conductive laminate for a heater has a substrate containing a thermoplastic resin and a conductive layer, the conductive layer is a cured product of a conductive composition containing a resin (A) and conductive fine particles (B); The conductive layer satisfies the following (1) and (2). (1) The breaking elongation in an atmosphere of 160°C is 90 to 300%. (2) The rate of change in the resistance value of the conductive layer when stretched by 40% in an atmosphere at 160 °C (R 40 ) and the rate of change in the resistance of the conductive layer when the elongation rate is 80% (R 80 ) and the ratio (R 80 / R 40 ) is less than or equal to 5.0.

[0010] In one embodiment of the conductive laminate for a heater in the present invention, the conductive layer has a resistance value (R T80 ) and resistance per cm in an atmosphere at 20°C / (R T20 ) and the ratio (R T80 / R T20 ) is less than or equal to 2.0.

[0011] In one embodiment of the conductive laminate for a heater in the present invention, the conductive fine particles (B) contain flaky conductive fine particles (B1) having an aspect ratio of 20 to 80, and the conductive composition contains a crosslinking agent (C).

[0012] In one embodiment of the conductive laminate for a heater of the present invention, the conductive fine particles (B) include chain-spherical conductive fine particles (B2).

[0013] In one embodiment of the conductive laminate for heaters of the present invention, the conductive fine particles (B) include one or more types of conductive fine particles selected from the group consisting of silver powder, copper powder, silver-coated powder, copper alloy powder, conductive oxide powder, and carbon fine particles.

[0014] One embodiment of the conductive laminate for a heater of the present invention contains a crosslinking agent (C).

[0015] In one embodiment of the conductive laminate for a heater of the present invention, the crosslinking agent (C) contains a trifunctional blocked isocyanate crosslinking agent.

[0016] In one embodiment of the conductive laminate for a heater of the present invention, the content of the resin (A) in the conductive composition is 8 to 40 mass % in the solid content of the conductive composition.

[0017] In one embodiment of the conductive laminate for a heater of the present invention, the substrate includes a film selected from polycarbonate, polymethyl methacrylate, polypropylene, and polyethylene terephthalate, or a laminate film thereof.

[0018] The three-dimensional molded heater in the present invention is a heater having a structure in which a conductive layer is laminated on a substrate, The conductive laminate for a heater of the present invention is formed into a three-dimensional shape including an uneven surface or a three-dimensional curved surface.

[0019] The molded body heater in the present invention is a heater in which the conductive laminate for heaters is integrated with a molded article having a three-dimensional shape including a three-dimensional curved surface.

[0020] A first method for producing a molded heater according to the present invention includes a step of arranging the conductive laminate for a heater of the present invention on a molded article, and a step of integrating the conductive laminate for heaters and the molded product by an overlay molding method.

[0021] A second method for producing a molded heater according to the present invention includes a step of forming the conductive laminate for a heater according to the present invention into a three-dimensional shape including an uneven surface or a three-dimensional curved surface, placing the molded conductive laminate for heaters in a mold for injection molding; and forming a molded article by injection molding, and integrating the molded article with the conductive laminate for a heater after the molding. Effect of the Invention

[0022] According to the present invention, it is possible to provide a conductive laminate for heaters in which the decrease in electrical conductivity due to tensile force and shear stress under high temperatures and the difference in wiring resistance value that arises due to differences in the degree of deformation are suppressed, as well as a three-dimensional molded heater and molded body heater that are excellent in sufficient heat generation property and heat generation uniformity within the three-dimensional surface, and a method for manufacturing the above heater. [Brief description of the drawings]

[0023] [Figure 1] 1 is a schematic cross-sectional view showing an example of a conductive laminate for a heater of the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing another example of the conductive laminate for a heater of the present invention. [Diagram 3] FIG. 2 is a schematic process diagram showing an example of a method for manufacturing a three-dimensional molded heater. [Figure 4] FIG. 4 is a schematic process diagram showing another example of the first manufacturing method for a molded body heater. [Diagram 5] FIG. 4 is a schematic process diagram showing another example of the second manufacturing method for a molded body heater. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The conductive laminate for a three-dimensional molded heater, the three-dimensional molded heater, the molded heater, and the manufacturing method thereof according to the present invention will be described in detail below.

[0025] In this specification, the heater for heaters refers to three-dimensional molded heaters and molded body heaters. The three-dimensionally molded heater in this specification is a heater obtained by molding a conductive laminate for heaters into a three-dimensional shape, and will be described in detail later. The molded body heater in this specification refers to a heater in which a conductive laminate for heaters and a molded body are integrated together, and will be described in detail later. In this specification, the term "cured product" refers not only to products that have been cured by a chemical reaction, but also to products that have been cured without a chemical reaction, such as products that have been hardened by volatilization of a solvent.

[0026] [Conductive laminate for heaters] The conductive laminate for a heater of the present invention comprises a substrate containing a thermoplastic resin and a conductive layer, and the conductive layer is a cured product of a conductive composition.

[0027] <Elongation at break of conductive laminate for heater> In the present invention, the conductive layer has a breaking elongation rate in an atmosphere of 160° C. of 90 to 300%. The breaking elongation in an atmosphere of 160 ° C. is a value measured by the following method under heating conditions of 160 ° C. using a tensile tester equipped with a heating chamber having sufficient thermal insulation from the outside air. Specifically, first, a lead wire is connected to the conductive layer of a heater conductive laminate having a linear conductive layer at two positions corresponding to the gripping positions of the test piece during the tensile test by a publicly known means such as a conductive metal tape or crimping of a metal terminal. Then, the unconnected ends of the two lead wires are connected to a tester outside the heating chamber, and the linear resistance value of the conductive layer between the gripping positions is measured in real time while the heater conductive laminate is stretched using a tensile tester, and the elongation rate when the linear resistance value exceeds 100 MΩ (effectively electrically disconnected state) is defined as the breaking elongation rate in the present invention. In addition, in the present invention, the conditions for stretching using the tensile tester are a constant tensile speed of 10 mm / min, and the elongation rate is calculated using the following formula. (Elongation rate) [%] = {(length after stretching - length before stretching) / (length before stretching)} x 100 When the breaking elongation is 90 to 300%, even when the heater is formed into a shape with a very steep rise, it is possible to exhibit excellent heater function without breaking. On the other hand, when the breaking elongation is less than 90%, when the heater is formed into a three-dimensional shape that was not possible with the conventional technology, breakage occurs as in the past, and the heater function cannot be exhibited. In addition, the yield is also poor, so it is not suitable for practical use. On the other hand, when the breaking elongation is more than 300%, although there is no disadvantage in terms of formability due to the high elongation, it is difficult to ensure the required performance in terms of conductivity, so this is also not suitable for practical use.

[0028] <Ratio of change in resistance value of conductive laminate for heater R 80 / R 40 > In the present invention, the resistance change rate ratio (R 80 / R 40 ) is 5.0 or less. Note that R 80 / R 40 is the rate of change in the resistance of the conductive layer when it is stretched by 40% in an atmosphere at 160 °C (R 40) and the rate of change in the resistance of the conductive layer when the elongation rate is 80% (R 80 ) is the ratio. R in the present invention X is the rate of change in the resistance value of the conductive layer when stretched to an elongation rate of X% in an atmosphere at 160 °C, relative to an elongation rate of 0%, and is the difference between the linear resistance value at the elongation rate of 0% (r0) and the linear resistance value after stretching to an arbitrary elongation rate of X% under heating conditions at 160 °C (r x ) and the ratio (r x / r0). Note that r0 and r x In both cases, the resistance between two points was evaluated with a tester at 20°C, and the two measurement points were the same before and after stretching. Therefore, if the measurement point interval for linear resistance is 10 cm at an elongation rate of 0%, the measurement point interval for linear resistance is 15 cm at an elongation rate of 50%. R 80 / R 40 is preferably 5.0 or less, and particularly preferably 4.0 or less. 80 / R 40 By making the R equal to or less than 5.0, it is possible to manufacture a sheet heating element that has high heat generation uniformity within a three-dimensional surface and is excellent in safety, even when manufacturing a three-dimensional molded heater having molded portions with different elongation rates, and a molded heater. 80 / R 40 If the value is higher than 5.0, not only will the heat generation uniformity within the three-dimensional surface be low, making product design difficult, but it will also pose safety risks, which is undesirable.

[0029] [Conductive composition] The conductive composition of the present invention contains a resin (A) and conductive fine particles (B).

[0030] The present inventors have investigated a screen-printable conductive composition in order to manufacture a conductive laminate for heaters that can be applied to three-dimensional shapes and has process suitability for integration with molded products. In order to apply the composition to the manufacture of a conductive laminate for heaters, various adjustments were made to the resin structure and conductive fine particles, and the inventors found that, depending on the composition of the conductive composition, particularly the binder composition and the particle shape and amount of the conductive fine particles, when the obtained conductive laminate for heaters is thermoformed into a complex shape and then operated as a heater, uneven heat generation occurs due to differences in the degree of deformation for each part, resulting in extremely problematic uneven heat generation temperature.

[0031] Even if the conductive laminate for heaters has non-uniform heat generation due to differences in the degree of deformation in each region, when it is used as a flat film heater by itself, or when it is used in a state where it is bent into a two-dimensional curved shape, no performance problems will occur. However, when it is used as a three-dimensional heater molded into a non-flat three-dimensional shape, such as a concave-convex shape or a three-dimensional curved shape, or as a molded heater integrated with a part having a concave-convex shape or a three-dimensional curved shape, the conductive laminate for heaters is deformed to different degrees of elongation depending on the region during thermoforming. Then, it is presumed that disconnection or a decrease in conductivity occurs in the portion where the conductive layer cannot follow the deformation, resulting in the non-uniformity of the heat generation. At the same time, it is considered that the thermal expansion of the conductive layer due to heat generation increases the distance between the conductive particles, resulting in a decrease in conductivity. In other words, it is presumed that a significant decrease in heat generation occurs in the portion where the temperature becomes high locally during current flow due to the non-uniformity of heat generation. In addition, the uneven surface and three-dimensional curved surface in the present invention refer not only to a surface having a gentle curved cross section, but also to a three-dimensional surface having an acute angle or a rectangular shape in general. In other words, it refers to a three-dimensional shape that cannot be established only by deforming a plane without expanding or contracting. For example, it refers to a three-dimensional shape such as a hemisphere, a cone, a cylinder, or a square prism. In addition, when a certain shape has elements of both the above-mentioned plane or two-dimensional curved surface and a three-dimensional curved surface in a continuous three-dimensional surface, for example, a shape in which one or more partial hemispherical shapes are combined with a plane shape, it is a shape that cannot be established by deforming a plane without expanding or contracting as a whole, so it is also considered to be a three-dimensional curved surface. In other words, the uneven surface and three-dimensional curved surface in the present invention cannot be realized by bending a flat substrate, etc., and are shapes that can be realized, for example, by applying shaping by molding with stretching while the object is softened under heating, and have characteristics in which the direction of stretching and the degree of deformation associated with deformation vary from part to part.

[0032] Based on this knowledge, the present inventors conducted research and found that by incorporating conductive fine particles with a specific aspect ratio, combining conductive fine particles with different shapes, and introducing a specific binder resin crosslinking system into the conductive composition used in the conductive layer of the conductive laminate for heaters, when the heater is operated in a shape formed into an uneven surface or a three-dimensional curved surface, the unevenness of heat generation at each part with a different degree of deformation is suppressed, and the heat generation does not decrease even when the temperature rises due to heat generation, making it easier to obtain the desired heat generation. Note that the aspect ratio is one of the parameters related to the particle shape, and in the present invention, it refers to the ratio a / b of the long diameter a and the short diameter b of the particle. That is, it was confirmed that the conductive composition of the present invention exhibits uniform heat generation properties and heat generation properties at high temperatures regardless of the degree of deformation when it simultaneously contains flaky conductive fine particles (B1) having an aspect ratio of 20 to 80 as conductive particles and a crosslinking agent (C), or when it simultaneously contains the flaky conductive fine particles (B1), chain-spherical conductive fine particles (B2), and a crosslinking agent (C). It was also found that this tendency shows particularly favorable characteristics when a trifunctional blocked isocyanate crosslinking agent is used as the crosslinking agent (C). Although the principle of this tendency is not clear, it is speculated that the conductive particles have the above-mentioned shape characteristics, which increases the current path formed by the physical connection between the conductive particles, i.e., the conductive path, and the characteristics of the resin matrix cross-linked with a specific cross-linking agent are combined, so that the tensile stress during thermoforming is uniformly distributed throughout the conductive layer while maintaining appropriate extensibility, and stress concentration at specific locations is suppressed, resulting in the conductive path being maintained, i.e., local breakage is suppressed. It is also believed that a similar mechanism is also effective in suppressing the reduction in conductive paths due to thermal expansion at high temperatures.

[0033] Each component of the conductive composition for the conductive laminate for heaters of the present invention will now be described.

[0034] <Resin (A)> The conductive composition of the present invention contains a binder resin (A). By containing the resin (A), flexibility can be imparted to the conductive layer, and the film-forming property and adhesion to the substrate or the decorative layer are improved. As a result, breakage of the conductive layer due to stretching is suppressed.

[0035] The resin (A) can be appropriately selected from resins used in conductive compositions. Examples of the resin (A) include acrylic resins, vinyl ether resins, polyether resins, polyester resins, polyurethane resins, epoxy resins, phenoxy resins, polycarbonate resins, polyvinyl chloride resins, polyolefin resins, styrene block copolymer resins, polyamide resins, and polyimide resins. These may be used alone or in combination of two or more.

[0036] In the present invention, the resin (A) preferably has a substituent selected from a hydroxyl group, an amino group, a carboxyl group, and an acid anhydride group. By having two or more of such substituents in one molecule, the adhesion to a substrate or the like is improved, and the resin (A) can be three-dimensionally crosslinked by combining with a crosslinking agent (C) described later, which is effective in suppressing breakage of the conductive layer due to thermoforming, and therefore can be preferably used.

[0037] When the resin (A) has a functional group selected from a hydroxyl group, an amino group, a carboxyl group, and an acid anhydride group, the functional group value is preferably 1 mgKOH / g or more and 400 mgKOH / g or less, and more preferably 2 mgKOH / g or more and 350 mgKOH / g or less. The details of the calculation method of the functional group value will be described in the examples below. When the resin (A) has multiple types of functional groups, the functional value is the sum of the functional groups. For example, when the resin (A) has a hydroxyl group and a carboxyl group, the functional value is the sum of the hydroxyl value and the acid value of the resin (A).

[0038] The glass transition temperature (Tg) of the resin (A) is preferably 0°C or higher and 150°C or lower, and more preferably 5°C or higher and 120°C or lower, from the viewpoint of balancing between maintaining the conductivity of the conductive layer during stretching for molding and frictional stress for maintaining conductivity against shear stress resulting from the difference in deformability between the conductive laminate for heaters and the substrate of the molded product in the integration process with the molded product carried out at high temperatures.

[0039] In the present invention, the resin (A) may be synthesized by the methods described in the Examples below or other known methods, or a commercially available product having desired physical properties may be used. In the present invention, the resin (A) may be used alone or in combination of two or more kinds.

[0040] The content of the resin (A) in the conductive composition of the present invention is not particularly limited and may be appropriately adjusted depending on the application, etc., but is preferably 5% by mass or more and 50% by mass or less, and more preferably 8% by mass or more and 40% by mass or less, based on the total solid content contained in the conductive composition. If the content of the resin (A) is equal to or more than the above lower limit, the film-forming property and the adhesion to the substrate, etc. are improved, and flexibility can be imparted to the conductive layer. On the other hand, if the content of the resin (A) is equal to or less than the above upper limit, the content of the flake-shaped conductive fine particles (B) can be relatively increased, and a conductive layer with excellent conductivity can be formed.

[0041] <Conductive fine particles (B)> The conductive fine particles (B) exhibit conductivity due to contact between the conductive fine particles within the conductive layer, and in the present invention, an appropriate one is selected from those that can obtain conductivity without high-temperature heat treatment and are used. The conductive fine particles used in the present invention include metal fine particles, carbon fine particles, conductive oxide fine particles, and the like. Examples of metal fine particles include powders of metal elements such as gold, silver, copper, nickel, chromium, palladium, rhodium, ruthenium, indium, aluminum, tungsten, malbutene, and platinum, as well as alloy powders such as copper-nickel alloys, silver-palladium alloys, copper-tin alloys, silver-copper alloys, and copper-manganese alloys, and metal-coated powders in which the surfaces of the above-mentioned metal element powders or alloy powders are coated with silver or the like. Examples of carbon fine particles include carbon black, graphite, and carbon nanotubes. Examples of conductive oxide fine particles include silver oxide, indium oxide, tin oxide, zinc oxide, and ruthenium oxide.

[0042] In the present invention, it is preferable to contain one or more conductive fine particles selected from silver powder, copper powder, silver-coated powder, copper alloy powder, conductive oxide powder, and carbon fine particles. By using these conductive fine particles (B), a conductive layer with excellent conductivity can be formed without sintering. Therefore, the conductive layer containing the conductive fine particles (B) has excellent extensibility when molded into a three-dimensional heater and a molded heater described later, and it is possible to form a conductive layer that has excellent conductivity even after molding.

[0043] The shape of the conductive fine particles (B) is not particularly limited, and spherical, flake-like, chain-spherical, and other shapes can be used as appropriate. From the viewpoint of maintaining appropriate extensibility and suppressing localized loss of conductive paths during deformation due to thermoforming or thermal expansion at high temperatures, however, flake-like particles with an aspect ratio of 20 to 80 are more preferred as conductive particles of a uniform shape. In the present invention, "spherical" refers to all particles with a low aspect ratio, such as a perfect sphere, an egg shape, a crushed sphere, a gravel shape, or a polyhedron shape, specifically an aspect ratio of about 1 to 2. In addition, in the present invention, "flake-like" refers to all two-dimensional flat shapes, such as scale-like, flaky, thin plate-like, flat, sheet-like, etc. Furthermore, in the present invention, "chain-like" refers to all amorphous shapes in which a plurality of the above-mentioned spherical conductive fine particles are directly fused or bonded together.

[0044] Hereinafter, in the present invention, the flake-like conductive fine particles having an aspect ratio of 20 to 80 are referred to as "conductive fine particles (B1)", and the chain-like conductive fine particles are referred to as "conductive fine particles (B2)".

[0045] The D50 particle size of the conductive fine particles (B) is not particularly limited, but from the viewpoints of dispersibility and printability in the conductive composition, maintenance of conductivity during molding, and resistance to injection molding process with molten resin or conformity to the shape of the resin molded product at high temperatures, it is preferably 0.2 μm or more and less than 30 μm, and particularly preferably 0.7 μm or more and less than 15 μm. In the present invention, the average particle size of the conductive fine particles (B) is calculated as follows. In accordance with the laser diffraction / scattering method described in JIS M8511 (2014), a laser diffraction / scattering type particle size distribution measuring device (Microtrack 9220FRA manufactured by Nikkiso Co., Ltd.) is used to add an appropriate amount of the conductive fine particles (B) to an aqueous solution containing 0.5 vol.% of a commercially available surfactant polyoxyethylene octylphenyl ether (Triton X-100 manufactured by Roche Diagnostics Co., Ltd.) as a dispersant, and then irradiated with 40 W ultrasonic waves for 180 seconds while stirring, and then measurement was performed. The calculated median diameter (D50) value was taken as the average particle size of the conductive fine particles (B).

[0046] In the present invention, the conductive fine particles (B) may be used alone or in combination of two or more kinds. The content of the conductive fine particles (B) in the conductive composition of the present invention may be adjusted according to the application and is not particularly limited, but is preferably 50% by mass or more and 90% by mass or less, and more preferably 55% by mass or more and 85% by mass or less, based on the total solid content contained in the conductive composition. If the content of the conductive fine particles (B) is equal to or more than the above lower limit, a conductive layer having excellent conductivity can be formed. If the content of the conductive fine particles (B) is equal to or less than the above upper limit, the content of the resin (A) can be increased, improving film-forming properties and adhesion to molded products, and imparting flexibility to the conductive layer. When two or more kinds of conductive fine particles (B) are used in combination, it is particularly preferable to use a combination of the flaky conductive fine particles (B1) having an aspect ratio of 20 to 80 and the chain-shaped conductive fine particles (B2) in order to maintain appropriate extensibility and to suppress localized conductive path loss during deformation due to thermoforming or thermal expansion at high temperatures. In this case, the weight ratio of the flaky conductive fine particles (B1) to the chain-like conductive fine particles (B2) is more preferably 90:10 to 40:60.

[0047] <Crosslinking agent (C)> In the present invention, a crosslinking agent (C) may be additionally used to crosslink the resin (A). The crosslinking agent (C) may be appropriately selected from those having two or more reactive functional groups in one molecule that can crosslink with the reactive functional group of the resin (A). Examples of such reactive functional groups include epoxy groups, isocyanate groups, blocked isocyanate groups, alkyloxyamino groups, aziridinyl groups, oxetanyl groups, carbodiimide groups, and β-hydroxyalkylamide groups. Among these, it is particularly preferable to use a trifunctional blocked isocyanate crosslinking agent from the viewpoint of maintaining appropriate extensibility and suppressing localized loss of conductive paths during deformation due to thermal molding or thermal expansion at high temperatures. The blocked isocyanate is not particularly limited, and may be an isocyanate compound in which the isocyanate group of a bifunctional isocyanate such as hexamethylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, isophorone diisocyanate, or a bifunctional or higher isocyanate such as an allophanate, biuret, adduct, prepolymer, or isocyanurate is protected (blocked) with ε-caprolactam, MEK oxime, etc. Specific examples include those in which the isocyanate group of the above isocyanate compound is blocked with ε-caprolactam, MEK oxime, cyclohexanone oxime, pyrazole, 3,5-dimethylpyrazole, diisopropylamine, diethyl malonate, ethyl acetoacetate, phenol, etc. By using such a combination, the decrease in electrical conductivity associated with elongation during thermoforming and the variation in electrical conductivity associated with differences in elongation rate are particularly suppressed, and a conductive layer having uniform and excellent electrical conductivity can be obtained even after molding into a three-dimensional shaped heater and a molded body heater.

[0048] The crosslinking agent (C) is preferably used in an amount of 0.05 to 30 parts by mass, and more preferably 0.3 to 25 parts by mass, per 100 parts by mass of the resin (A).

[0049] <Solvent (D)> In the present invention, the composition contains a solvent (D). The solvent (D) dissolves the resin (A) and imparts fluidity and printability. Furthermore, the solvent (D) adjusts the spread and entanglement of the molecular chains of the resin (A) in the composition, improves the wettability to the substrate, and improves the patterning accuracy during printing.

[0050] The solvent (D) of the present invention can be any known or used solvent without any particular limitation, so long as it can dissolve the resin (A). The solvent (D) can be used alone or in combination of two or more. Even if it is solid at room temperature, it can be used without any problem if it is mixed with a solvent of another structure to become liquid. Furthermore, the solvent (D) is not particularly limited, but from the viewpoint of continuous screen printing, it is preferable that the boiling point is 180°C or more and 270°C or less. For example, glycol esters such as 2-ethoxy(2-ethoxy)ethyl acetate and 2-ethoxy(2-ethoxy)butyl acetate, 2-ethoxy(2-ethoxy)ethanol, 2-butoxy(2-ethoxy)ethanol, diethylene glycol diethyl ether, glycol ethers such as dipropylene glycol monomethyl ether acetate, gamma butyrolactone, isophorone, tetralin, dipropylene glycol monomethyl ether acetate, etc. can be mentioned, but are not particularly limited.

[0051] <Optional ingredients> The conductive composition of the present invention may further contain other components as necessary, such as the solvent (D), dispersants, friction resistance improvers, infrared absorbing agents, ultraviolet absorbing agents, fragrances, antioxidants, organic pigments, inorganic pigments, defoamers, silane coupling agents, plasticizers, flame retardants, moisturizing agents, etc.

[0052] <Method of manufacturing conductive composition> The method for producing the conductive composition of the present invention may be any method for dissolving or dispersing the resin (A), the conductive fine particles (B), and other components used as necessary, and the conductive composition can be produced by mixing them by a known mixing means.

[0053] [Conductive laminate for heaters] The conductive laminate for a heater of the present invention is a conductive laminate for a heater comprising a substrate and a conductive layer, The conductive layer is characterized in that it is a cured product of the conductive composition.

[0054] <Layer configuration> The layer structure of the conductive laminate for a heater of the present invention will be described with reference to Figures 1 and 2. Figures 1 and 2 are schematic cross-sectional views showing one example of the conductive laminate for a heater of the present invention. The conductive laminate 10 for a heater shown in the example of Fig. 1 includes a conductive layer 2 on a substrate 1. The conductive layer 2 may be formed on the entire surface of the substrate 1, or may be formed in a desired pattern as in the example of Fig. 1. The conductive laminate 10 for a heater shown in the example of Fig. 2 has a decorative layer 3 on a substrate 1, and a conductive layer 2 on the decorative layer 3. As shown in the example of Fig. 2, the conductive laminate 10 may also have a pin 4 on the conductive layer 2 for connection to an output circuit. Although not shown, a resin layer for protecting the conductive layer or the pins may be provided on the conductive layer 2 or on the pins 4, and the resin layer may be an adhesive layer or a pressure-sensitive adhesive layer for improving adhesion to the substrate described below. In addition, although not shown, when the conductive laminate 10 for a heater of the present invention has a decorative layer 3, in addition to the example of FIG. 2, the laminate may have a layer structure in which the decorative layer 3 is provided on one surface of the substrate 1 and the conductive layer 2 is provided on the other surface. The conductive laminate for a heater of the present invention comprises at least a substrate and a conductive layer, and may have other layers as necessary. Each layer of such a conductive laminate for a heater will be described below.

[0055] <Substrate> In the present invention, the substrate can be appropriately selected from those having flexibility and extensibility to such an extent that they can conform to the shape to be molded at the molding temperature during molding. In addition, it is preferable to select the substrate according to the application and manufacturing method of the three-dimensional molded heater and molded body heater after molding. For example, when vacuum molding, pressure molding, vacuum pressure molding, ultra-high pressure air molding, press molding, the overlay molding method as described below, or the film insert molding method is adopted as a manufacturing method for a three-dimensional molded heater and a molded body heater, it is possible to place a base material in the outermost layer and mold the base material as a protective layer for the conductive layer, and therefore it is also possible to select the material of the substrate in consideration of its functionality as a protective layer for the conductive layer.

[0056] The material of the substrate can be appropriately selected from the above viewpoints, and may be, for example, a film containing a thermoplastic resin such as polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polystyrene, polyimide, polyamide, polyethersulfone, polyethylene naphthalate, polybutylene terephthalate, polyvinyl chloride, polyethylene, polypropylene, cycloolefin polymer, ABS (acrylonitrile-butadiene-styrene copolymer resin), AES (acrylonitrile-ethylene-styrene copolymer resin), Kaidac (acrylic modified vinyl chloride resin), modified polyphenylene ether, and a polymer alloy consisting of two or more of these resins, or a laminated film thereof. Among them, a film selected from polycarbonate, polymethyl methacrylate, polypropylene, and polyethylene terephthalate, or a laminated film thereof is preferable. As the laminated film, a laminated film of polycarbonate and polymethyl methacrylate is preferable. The method for producing the laminated film of polycarbonate and polymethyl methacrylate is not particularly limited. A polycarbonate film and a polymethyl methacrylate film may be laminated together, or polycarbonate and polymethyl methacrylate may be co-extruded to form a laminated film. It is also preferable that the surfaces of these substrates have been subjected to a modification treatment such as a corona treatment.

[0057] In addition, if necessary, an anchor coat layer may be provided on the substrate for the purpose of improving the printability of the conductive composition, and the conductive composition may be printed on the anchor coat layer to form a conductive laminate for heaters. The anchor coat layer is not particularly limited as long as it has good adhesion to the substrate and further to the conductive composition and follows the deformation of the substrate during molding, and organic fillers such as resin beads and inorganic fillers such as metal oxides may also be added as necessary. The method for providing the anchor coat layer is not particularly limited, and it can be obtained by coating, drying, and curing using a conventionally known coating method. Furthermore, if necessary, a hard coat layer may be provided on the substrate to prevent the surface from being scratched, and a conductive composition and, if necessary, a decorative layer may be printed on the opposite surface to form a conductive laminate for a heater. The hard coat layer is not particularly limited as long as it has good adhesion to the substrate and surface hardness and follows the deformation of the substrate during molding, and organic fillers such as resin beads and inorganic fillers such as metal oxides may also be added as necessary. The method for providing the hard coat layer is not particularly limited, and it can be obtained by coating, drying, and curing using a conventionally known coating method.

[0058] When the conductive laminate for a heater of the present invention has a decorative layer, it is preferable to select a substrate having transparency.

[0059] The thickness of the substrate is not particularly limited, but can be, for example, from 10 μm to 500 μm, and preferably from 20 μm to 450 μm.

[0060] <Conductive layer and method for forming same> In the conductive laminate for a heater of the present invention, the conductive layer is a cured product of the conductive composition. The conductive layer may be a patterned conductive layer or a solid conductive layer. The method for forming the conductive layer is not particularly limited, but in the present invention, it is preferable to form the conductive layer by screen printing, pad printing, stencil printing, screen offset printing, dispenser printing, gravure offset printing, reverse offset printing, or microcontact printing, and it is more preferable to form the conductive layer by screen printing. In the screen printing method, it is preferable to use a fine mesh screen, particularly a fine mesh screen of about 300 to 650 mesh, in order to meet the demands of high-definition conductive circuit patterns. In this case, the open area of ​​the screen is preferably about 20 to 50%. The screen wire diameter is preferably about 10 to 70 μm. Types of screens include polyester screens, combination screens, metal screens, nylon screens, etc. When printing with a highly viscous paste, a high-tension stainless steel screen can be used. The squeegee for screen printing may be round, rectangular, or square, and an abrasive squeegee may be used to reduce the attack angle (the angle between the plate and the squeegee during printing). Other printing conditions may be appropriately designed from conventionally known conditions.

[0061] The conductive composition is printed by screen printing, and then heated to dry and cause a crosslinking reaction and harden. For sufficient volatilization of the solvent and crosslinking reaction, the heating temperature is preferably 80 to 230° C. and the heating time is preferably 10 to 120 minutes, thereby making it possible to obtain a patterned conductive layer. The pattern of the conductive layer is not particularly limited, and may be, for example, a straight line, a curve, a mesh, a solid pattern or a solid pattern having a partial square, circle, diamond shape, or any combination thereof, or the entire conductive layer may be a solid pattern on one side, and is not limited as long as the conductive layer functions as a conductive circuit or as a part of a conductive circuit. The patterned conductive layer may be provided with an insulating layer, if necessary, so as to cover the conductive pattern. The insulating layer is not particularly limited, and any known insulating layer may be used.

[0062] The thickness of the conductive layer may be appropriately adjusted depending on the required conductivity, etc., and is not particularly limited. For example, it can be 0.5 μm or more and 20 μm or less, and preferably 1 μm or more and 15 μm or less.

[0063] <Decorative layer and method for forming same> The conductive laminate for heaters of the present invention may have a decorative layer from the viewpoint of the design of the resulting three-dimensional molded heater and molded body heater. The decorative layer may be a layer having a single color, or may have any pattern. The decorative layer can be formed, for example, by preparing a decorative ink containing a coloring material, a resin, and a solvent, and then applying the decorative ink to the substrate by a known printing method. The coloring material can be appropriately selected from known pigments and dyes, and the resin is preferably appropriately selected from the same resins as the resin (A) in the conductive composition of the present invention. The thickness of the decorative layer is not particularly limited, but may be, for example, from 0.5 μm to 10 μm, and preferably from 1 μm to 5 μm. The decorative layer may be provided on the surface of the substrate opposite to the surface on which the conductive layer is provided, between the substrate and the conductive layer, or on the conductive layer.

[0064] According to the conductive laminate for heaters of the present invention, it is possible to obtain a three-dimensional molded heater and a molded heater in which a conductive circuit is formed on any substrate surface, such as an uneven surface or a curved surface.

[0065] [3D molded heater] The three-dimensionally molded heater of the present invention is a heater having a heater circuit in which the conductive laminate for a heater, in which at least a conductive layer is laminated on a substrate, is thermoformed into any three-dimensional shape including curved surfaces and uneven surfaces.

[0066] <Manufacturing method of three-dimensional molded heater> The method for producing a three-dimensional molded heater in the present invention comprises a step of molding the conductive laminate for a heater into a predetermined shape. Hereinafter, the method will be described with reference to FIG. 3. However, since the method for producing the conductive laminate for a heater is as described above, the description thereof will be omitted here.

[0067] First, the heater conductive laminate 10 is placed on a mold 11 (FIG. 3(A)). Next, the heater conductive laminate 10 is heated and softened, or while being softened, sucked into the mold 11 by vacuum or pressed against the mold by compressed air, or both are used in combination, and the heater conductive laminate 10 is molded by the mold 11 (FIG. 3(B)), and a three-dimensional molded heater 30 is obtained (FIG. 3(C)). At this time, the heater conductive laminate 10 may be molded so that the conductive layer faces either the mold 11 side or the opposite side, and this is selected depending on the final use of the three-dimensional molded heater 30.

[0068] [Molded body heater] The molded heater of the present invention is a heater in which a conductive laminate for heaters, in which at least a conductive layer is laminated on a substrate, has a heater circuit that is thermoformed into any three-dimensional shape including curved surfaces and unevenness, and means that the conductive laminate for heaters is integrated with a molded product that is thermoformed into any three-dimensional shape including curved surfaces and unevenness. By integrating the conductive laminate for heaters with a molded product, the mechanical strength increases when used as a three-dimensional circuit component, and it is easy to obtain a strength suitable for practical use alone, which is preferable.

[0069] <Molded object> The molded product of the present invention is a core material that can be used to provide structural strength to the heater circuit that has been thermoformed into an arbitrary three-dimensional shape including the curved surface and unevenness, and when the conductive laminate for the heater is molded into an arbitrary three-dimensional shape, the physical strength can be enhanced by integrating the molded product with the heater circuit. The material of the molded product of the present invention is not particularly limited, and may be resin, FRP, metal, ceramic, glass, etc., as long as it is compatible with the method used. The molded product of the present invention may be prepared in advance by any method, or may be molded from a molten state at the same time when the conductive laminate for the heater is molded into an arbitrary three-dimensional shape, but in the latter case, the material of the molded product is preferably resin from the viewpoint of the heat resistance of the substrate.

[0070] Hereinafter, two embodiments of the method for producing the molded heater of the present invention will be described. Note that the molded heater of the present invention may be produced using the conductive composition for heaters of the present invention, and the method is not limited to these embodiments.

[0071] <First manufacturing method of molded heater> A first method for producing a molded heater in the present invention includes a step of arranging a conductive laminate for a heater, and a step of integrating the conductive laminate for heaters and the molded product by an overlay molding method. Hereinafter, the method will be described with reference to Fig. 4, but the method for producing the conductive laminate for heaters is as described above, so the description will be omitted here.

[0072] Fig. 4 is a schematic process diagram showing an example of a first manufacturing method for a molded body heater. Fig. 4(A) to (C) respectively show a conductive laminate for a heater 10 and a molded body 20 arranged in a chamber box of a TOM (Three dimension Overlay Method) molding machine, and Fig. 4(B) and (C) omit the chamber box. In the first manufacturing method, first, the molded product 20 is placed on the table of the lower chamber box 22. Next, the conductive laminate 10 for heater of the present invention is passed between the upper chamber box 21 and the lower chamber box 22 and placed on the molded product 20 (FIG. 4(A)). At this time, the conductive laminate 10 for heater may be placed so that the conductive layer faces either the molded product 20 side or the opposite side to the molded product 20, and this is selected depending on the final use of the molded product heater. Next, the upper and lower chamber boxes are made into a vacuum state, and then the conductive laminate for heater is heated. Next, the table is raised to raise the molded product 20 15 (FIG. 4(A)). Next, only the inside of the upper chamber box 21 is opened to the atmosphere. At this time, the conductive laminate 10 for heater is pressed 16 against the molded product 20 side (FIG. 4(B)), and the conductive laminate 10 for heater and the molded product 20 are bonded together to obtain an integrated molded product heater 40 (FIG. 4(C)).

[0073] In the above-mentioned first manufacturing method, the molded product 20 can be prepared in advance by any method, and the material is not particularly limited, and it may be made of resin or metal.

[0074] <Second manufacturing method of molded heater> A second method for producing a molded heater according to the present invention includes a step of forming the conductive laminate for a heater into a predetermined shape, placing the molded conductive laminate for heaters in a mold for injection molding; and forming a molded article by injection molding, and integrating the molded article with the conductive laminate for a heater after the molding. Hereinafter, the method for producing the conductive laminate for a heater will be described with reference to FIG. 5, but since the method is as described above, the description thereof will be omitted here. The second manufacturing method is sometimes called the film insert molding method.

[0075] Fig. 5 is a schematic process diagram showing an example of the second manufacturing method of the molded heater. In the second manufacturing method, the conductive laminate 10 for the heater is placed on a mold 11 (Fig. 5(A)), and then, while the conductive laminate 10 for the heater is heated and softened or in the process of softening, it is sucked into the mold by vacuum or pressed against the mold by compressed air, or both are used in combination, and the conductive laminate 10 for the heater is molded by the mold 11 (Fig. 5(B)). At this time, the conductive layer of the conductive laminate 10 for the heater may be molded so as to face either the mold 11 side or the side opposite to the mold 11, and this is selected depending on the final use of the molded heater. Next, the molded conductive laminate for a heater 10 is removed from the metal mold 11 and then placed in an injection molding metal mold 12, and resin is injected 14 from an opening 13 (FIG. 5(C)) to form a molded product 20, and the molded conductive laminate for a heater 10 and the molded product 20 are integrated to obtain a molded heater 40 (FIG. 5(D)).

[0076] In the second manufacturing method, it is not necessary to prepare the molded product 20 in advance, and molding of the molded product 20 and integration with the molded conductive laminate for heater 10 prepared in advance can be performed simultaneously inside an injection molding machine. The material of the molded product 20 can be appropriately selected from known resins used for injection molding.

[0077] The molded heater obtained in this way makes it possible to implement heating functions in the plastic housings of home appliances, automobile parts, and other appliances, and is extremely useful for preventing condensation and snow buildup on equipment, as well as for energy-efficient local heating. EXAMPLES

[0078] The present invention will be described in more detail below using examples, but the following examples are not intended to limit the present invention in any way. In the examples, "parts" means "parts by mass" and "%" means "% by mass". The weight average molecular weight in the examples is a polystyrene-equivalent molecular weight measured using a GPC (gel permeation chromatography) "HLC-8320" manufactured by Tosoh Corporation.

[0079] <Functional value> In the examples, the "functional group value" is calculated based on the molecular weight per functional group of each raw material (referred to as the functional group equivalent) and is expressed as the amount of functional groups per 1 g of raw material converted into an equimolar amount of potassium hydroxide (mg) using the following formula: (Functional group value) [mgKOH / g] = (56.1 x 1000) / (functional group equivalent) The above-mentioned functional group value is a general term for an amount expressed, for example, as an acid value when the functional group is a carboxyl group, a hydroxyl value when the functional group is a hydroxyl group, or an amine value when the functional group is an amino group. When comparing the functional group ratios of substances having different functional groups, those having the same value of the above-mentioned functional group value can be considered to have the same molar amount of functional groups.

[0080] When titration of potassium hydroxide is used to quantify the functional groups such as carboxyl groups and hydroxyl groups, the above-mentioned functional group values ​​(acid value and hydroxyl value) can be directly determined from the appropriate amount of potassium hydroxide used for neutralization using a known and commonly used measurement method specified in, for example, JIS K 0070, and can be treated in the same way as the values ​​calculated by the above-mentioned calculation formula. In addition, even when the titration with potassium hydroxide is not used to determine the functional group value, such as isocyanate groups, the functional group value can be calculated in terms of potassium hydroxide for convenience by using the functional group equivalent weight derived from each measured value representing the amount of functional group and the above calculation formula. A specific calculation example is shown below.

[0081] Calculation example: Calculate the amount of isocyanate in trifunctional isocyanate compound "X" that has an isocyanate group and is 23% as measured by the method specified in JIS K 6806 (method of reacting isocyanate groups with n-dibutylamine and titrating the remaining n-dibutylamine with an aqueous hydrochloric acid solution). The functional group equivalent of trifunctional isocyanate compound "X" is calculated as follows from the above isocyanate amount (%) and the molecular weight of the isocyanate group (NCO = 44g / mol). (Functional group equivalent of "X") = 1 / (0.23 / 44) = 191.3 From the functional group equivalent of this trifunctional isocyanate compound "X" and the above-mentioned formula for functional group value, the functional group value of the trifunctional isocyanate compound "X" can be calculated as follows. (Functional value of trifunctional isocyanate compound "X") [mgKOH / g] =(56.1×1000) / 191.3=293.3

[0082] <Resin (A1)~(A4)> The following resins were used as resins (A1) to (A4). Resin (A1): Polyester resin manufactured by Unitika, Elitel UE-3240, weight average molecular weight 41,000, glass transition point 40°C, contains 2 or more hydroxyl groups (functional value 5 mg KOH / g) per molecule. Resin (A2): Polyester resin manufactured by Unitika, Elitel UE-9600, weight average molecular weight 42,000, glass transition point 71°C, contains 2 or more hydroxyl groups (functional value 8mgKOH / g) per molecule. Resin (A3): Toa Gosei acrylic resin, Arfon UH-2170, weight average molecular weight 14,000, glass transition point 60°C, contains 2 or more hydroxyl groups (functional value 20mgKOH / g) per molecule. <Synthesis Example 1: Synthesis of Resin (A4)> A reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube was charged with 127.4 parts of polyester polyol ("Elitell UE-9820" manufactured by Unitika Ltd.), 19.2 parts of isophorone diisocyanate, and 32.5 parts of diethylene glycol monoethyl ether acetate, and reacted at 90°C for 3 hours under a nitrogen stream. Then, 5.5 parts of isophorone diamine was added and reacted at 90°C for a further 2 hours, to obtain a urethane resin solution with a non-volatile content of 40% consisting of 40% urethane resin (A4) having a weight average molecular weight of 36,000, a glass transition point of 85°C, and containing two or more amino groups (functional value 4 mgKOH / g) per molecule, and 60% diethylene glycol monoethyl ether acetate solvent.

[0083] The following conductive particles, solvent, and crosslinking agent were used. <Conductive fine particles (B1-1)~(B1-5), (B2), (B3)> Conductive fine particles (B1-1): Fukuda Metal Foil Powder Co., Ltd., flake silver powder, average particle size 5.3 μm, aspect ratio 70 Conductive fine particles (B1-2): Fukuda Metal Foil Powder Co., Ltd., flake silver powder, average particle size 4.4 μm, aspect ratio 13 Conductive fine particles (B1-3): DOWA Electronics, flake-shaped silver-coated copper powder, silver coating amount 10%, average particle size 4.0 μm, aspect ratio 45 Conductive fine particles (B1-4): Ito Graphite Co., Ltd., flake graphite, average particle size 15 μm, aspect ratio 23 Conductive particles (B2): DOWA Electronics, chain-shaped silver powder, average particle size 1.9 μm Conductive fine particles (B3): DOWA Electronics, spherical silver powder, average particle size 0.8 μm

[0084] <Synthesis Example 2: Preparation of conductive particles (B1-5)> A 5% by mass solution of cellulose acetate butyrate (CAB551-0.2, manufactured by Eastman Chemical Co.) in MXD was applied to a 25μm-thick polyethylene terephthalate (PET) film using a bar coater, and then dried in a hot air drying oven at 100℃ for 20 minutes to form a release layer. A thin silver vapor deposition film was formed on the release layer at a deposition rate of 50nm / sec using high-frequency induction heating and vacuum deposition. Next, butyl acetate was sprayed onto the (PET) film surface on which the release layer and the thin silver vapor deposition film were formed to dissolve the release layer, and the thin silver vapor deposition film was scraped off with a doctor blade to obtain flaky silver particles. The mixture of the obtained silver particles and butyl acetate was pulverized using a jet mill and spray-dried to obtain flaky silver particles (B1-5) with an average particle size of 3.2 μm and an aspect ratio of 110.

[0085] <Crosslinking agents (C1) to (C3)> Crosslinker (C1): Baxeneden Chemicals trifunctional blocked isocyanate crosslinker solution, Trixene BI7982, containing three isocyanate groups blocked with dimethylpyrazole per molecule (functionality 168 mg KOH / g), non-volatile content 70% (solvent (D3): 2-methoxypropanol) Crosslinker (C2): Sumika Covestro Urethane Co., Ltd. trifunctional blocked isocyanate crosslinking agent solution, Desmodur BL-3475, containing three isocyanate groups blocked with diethyl malonate per molecule (functionality 147 mg KOH / g), non-volatile content 70% (solvent (D4): 1:1 mixed solvent of solvent naphtha and solvent (D5) butyl acetate) Crosslinker (C3): Mitsui Chemicals tetrafunctional epoxy crosslinker, TETRAD-X, contains four epoxy groups per molecule (functional value 622 mg KOH / g), non-volatile content 100%

[0086] <Solvents (D1)~(D5)> Solvent (D1): Benzyl alcohol, boiling point 207℃ Solvent (D2): Diethylene glycol monoethyl ether acetate, boiling point 217°C Solvent (D3): 2-methoxypropanol, boiling point 120℃ Solvent (D4): Solvent naphtha, boiling point 171℃ Solvent (D5): Butyl acetate, boiling point 126℃

[0087] <Other resins (F1)~(F2)> Resin (F1): Polyester resin manufactured by Unitika, Elitel UE-3200G, weight average molecular weight 33,000, glass transition point 65°C, contains 2 or more hydroxyl groups (functional value 6 mgKOH / g) per molecule. <Synthesis Example 3: Synthesis of resin (F2)> In a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, 20 g of a mixture of 10 g of n-butyl methacrylate and 10 g of methyl methacrylate, and 30 g of methyl ethyl ketone were introduced into a nitrogen-substituted three-neck flask, and the mixture was stirred with a stirrer (Three-One Motor, manufactured by Shinto Scientific Co., Ltd.) and heated to 65 ° C while flowing nitrogen into the flask. 80 mg of 2,2-azobis(2,4-dimethylvaleronitrile (V-65, manufactured by Wako Pure Chemical Industries, Ltd.) was added to the above mixture, and the mixture was heated and stirred at 65 ° C for 30 minutes. Next, 80 mg of V-65 was added, and the mixture was heated and stirred at 65 ° C for another hour. The resulting reaction liquid was poured into 1,000 mL of hexane while stirring, and the resulting precipitate was dried by heating to obtain a resin (F2) with a weight average molecular weight of 32,000, a glass transition point of 70 ° C, and no hydroxyl group.

[0088] <Production Example 1: Preparation of protective layer ink (G1)> 200 parts of a resin solution consisting of 80 parts of resin (F1) and 120 parts of solvent (D2) was prepared, to which 5 parts of crosslinker (C2) and 0.5 parts of a polymeric defoamer (Floren AC-2300C) were added and stirred uniformly to obtain a protective layer ink (G1).

[0089] <Production Example 2: Creation of Decorative Ink (H1)> 200 parts of a resin solution consisting of 80 parts of resin (F1) and 120 parts of solvent (D2) was prepared, and 20 parts of phthalocyanine blue pigment (LIONOL BLUE FG7351 manufactured by Toyo Color Co., Ltd.) and 10 parts by mass of titanium oxide pigment (TIPAQUE CR-93 manufactured by Ishihara Sangyo Kaisha, Ltd.) were stirred and mixed into this, and the mixture was kneaded in a three-roll mill (manufactured by Kodaira Seisakusho Co., Ltd.). After that, 5 parts of an isocyanate crosslinking agent (Desmodur N3300 manufactured by Sumika Covestro Urethane Co., Ltd., non-volatile content 100%) and 90 parts of solvent (D3) were added and stirred and mixed uniformly to obtain decorative ink (H1).

[0090] <Production Example 3: Creation of Decorative Ink (H2)> 59 parts of 2-phenoxyethyl acrylate, 10 parts of dispersant (SOLSPERSE41000 manufactured by Lubrizol), tris(N-nitroso-N-phenylhydroxyl) The mixture was mixed with 1 part of aluminium salt and stirred in a Silverson mixer (10 to 15 minutes, 2,000 to 3,000 rpm), and 50 parts of titanium oxide pigment (KRONOS2300, KRONOS) was added to the resulting homogeneous transparent liquid, which was then stirred in the same manner in the mixer. Dispersion was then carried out using a Dispermat circulation type bead mill (SL-012C1) and 0.65 mm zirconia beads at a peripheral speed of 15 m / sec for a dispersion time of 6 hours, to obtain a pigment dispersion. 30 parts of this pigment dispersion, 23.1 parts of 2-phenoxyethyl acrylate, 12 parts of isobornyl acrylate, 24 parts of N-vinyl caprolactam, 0.3 parts of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 1 part of isopropylthioxanthone, 2.8 parts of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, IRGACURE819 (manufactured by IGM Resins, 2.8 parts of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2 parts of resin (F2), and 2 parts of silicone additive (manufactured by Evonik, TEGORAD2010) were added and uniformly stirred and mixed to obtain decorative ink (H2).

[0091] <Production Example 4: Preparation of conductive composition (E1)> 20.0 parts of resin (A1) was dissolved in 30.0 parts of solvent (D1), and 80.0 parts of conductive fine particles (B1-1) were stirred and mixed. The mixture was kneaded using a three-roll mill (manufactured by Kodaira Seisakusho). Then, 1.0 part of crosslinker solution (consisting of 0.7 part of crosslinker (C1) and 0.3 part of solvent (D5)) was added, and the mixture was stirred and mixed uniformly using a planetary mixer to obtain a conductive composition (E1).

[0092] <Production Examples 5 to 23: Preparation of Conductive Compositions (E2) to (E20)> Conductive compositions (E2) to (E20) were obtained in the same manner as for conductive composition (E1), except that the types and amounts of resin, conductive fine particles, solvent, and crosslinking agent in conductive composition (E1) were changed as shown in Tables 1 to 3. The numerical values ​​for each material in Tables 1 to 3 are all in parts by mass.

[0093] <Examples 1 to 20> The conductive compositions (E1) to (E20) were printed on the substrate by a screen printer, and then heated in a hot air drying oven at 120°C for 30 minutes to obtain a conductive laminate for heaters having a conductive layer with two types of patterns: a solid rectangular pattern with a width of 15 mm, a length of 30 mm, and a thickness of 10 μm, and a linear pattern with a line width of 1 mm, a length of 120 mm, and a thickness of 10 μm. In this case, a polycarbonate film manufactured by Teijin, Panlite 2151 (thickness 300 μm) cut to 300 mm×210 mm was used as the substrate, and a semi-automatic screen printer, Minomat SR5575 manufactured by Minoscreen, was used as the printing machine.

[0094] <Example 21> A conductive laminate for a heater was obtained in the same manner as in Example 17, except that in Example 17, the substrate was changed to an acrylic resin film, Technoloy S001G (thickness 250 μm), manufactured by Sumitomo Chemical Co., Ltd., and the drying conditions in the hot air drying oven were changed to 80° C. for 30 minutes.

[0095] <Example 22> A conductive laminate for a heater was obtained in the same manner as in Example 17, except that in Example 17, the substrate was changed to a two-layer co-extrusion film of polycarbonate resin / acrylic resin, Technoloy C001 (thickness 125 μm) manufactured by Sumitomo Chemical Co., Ltd., and a conductive composition was printed on the polycarbonate resin side.

[0096] <Example 23> A conductive laminate for a heater was obtained in the same manner as in Example 17, except that the substrate was changed to an easily moldable PET resin film manufactured by Morino Kako Co., Ltd., an Emron PETG resin sheet (thickness 250 μm), and the drying conditions in the hot air drying oven were changed to 70°C and 30 minutes.

[0097] <Example 24> A conductive laminate for a heater was obtained in the same manner as in Example 17, except that the substrate was changed to a polypropylene film, Pure Thermo AG-306 (thickness 200 μm), manufactured by Idemitsu Unitech Co., Ltd., and the drying conditions in the hot air drying oven were changed to 80° C. for 30 minutes.

[0098] <Example 25> First, the decorative ink (H1) was applied onto the substrate using a blade coater so that the dry thickness was 2 μm, and then heated at 120° C. for 30 minutes to prepare a substrate with a decorative layer. At this time, a polycarbonate film manufactured by Teijin Ltd., Panlite 2151 (thickness 300 μm), cut to 300 mm × 210 mm, was used as the substrate. Next, a conductive laminate for a heater was obtained in the same manner as in Example 17, except that the substrate with the decorative layer was replaced with the substrate in Example 17, and the substrate, the decorative ink layer, and the conductive layer were laminated in that order.

[0099] <Example 26> Of the two types of conductive layers formed in Example 17, the protective layer ink (G1) was printed on the linear conductive layer having a line width of 1 mm, a length of 120 mm, and a thickness of 10 μm using the screen printing machine under the same conditions as above, so that both ends of the conductive layer were exposed in the length direction of the conductive layer and the remaining parts were covered to a width of 10 mm, a length of 100 mm, and a thickness of 15 μm. The resulting product was heated in a hot air drying oven at 120° C. for 30 minutes, thereby obtaining a conductive laminate for a heater, comprising the patterned conductive layer and a protective layer laminated so as to cover a portion of the conductive layer.

[0100] <Comparative Example 1> A photosensitive material having a photosensitive silver salt-containing layer on a substrate was exposed and developed using the so-called silver salt method to obtain a conductive laminate for a heater having a conductive layer having a rectangular solid pattern of 15 mm in width, 30 mm in length and 10 μm in thickness and a linear pattern of 1 mm in line width, 120 mm in length and 10 μm in thickness. In this case, a polycarbonate film, Panlite 2151 (thickness: 300 μm), manufactured by Teijin Limited, cut to 300 mm×210 mm was used as the substrate.

[0101] <Comparative Example 2> Of the two types of conductive layers formed in Comparative Example 1, the conductive layer of the linear pattern with a line width of 1 mm, length of 120 mm, and thickness of 10 μm was masked with Kapton tape at 10 mm on both ends, and the decorative ink (H2) was applied thereon with a blade coater to a dry film thickness of 30 μm, and a conveyor-type high-pressure mercury lamp was used to apply an integrated path light quantity of 500 mJ / cm. 2 The patterned conductive layer was cured by irradiating it with ultraviolet light at 400° C. to form a protective layer, and the Kapton tape was then removed to obtain a conductive laminate for a heater, comprising the patterned conductive layer and a protective layer laminated so as to cover a portion of the conductive layer.

[0102] <Comparative Examples 3 and 4: Preparation of Conductive Compositions (E21) and (E22)> Conductive compositions (E21) to (E22) were obtained in the same manner as for the conductive composition (E1), except that the types and amounts of the resin, conductive fine particles, solvent, and crosslinking agent in the conductive composition (E1) were changed as shown in Table 3. Then, a conductive laminate for a heater having a conductive layer was obtained in the same manner as in Example 1.

[0103] [Evaluation of conductive laminates for heaters] The obtained conductive laminate for heaters was evaluated as described below. The results are shown in Tables 1 to 3.

[0104] [(1) Volume resistivity measurement] The volume resistivity (Ω·cm) of the 15 mm×30 mm square solid conductive layers formed on the conductive laminates for heaters of Examples 1 to 26 and Comparative Examples 1 to 4 was measured using a resistivity meter (Mitsubishi Chemical Analytech Co., Ltd., Loresta GP MCP-T610 resistivity meter, JIS-K7194 compliant, 4-terminal 4-probe constant current application method) (4-terminal probes spaced 0.5 cm apart). The results are shown in Tables 1 to 3.

[0105] [(2) Peel adhesion evaluation] The conductive layer formed in the conductive laminate for heaters of Examples 1 to 26 and Comparative Examples 1 to 4 was cut into a square shape of 15 mm x 30 mm with a cutter knife using a 1 mm interval cross-cut guide manufactured by Gardner Co., Ltd., and cut into a grid pattern of 10 x 10 squares so as to penetrate the conductive layer. Cellophane tape manufactured by Nichiban Co., Ltd. was attached to the conductive layer to remove trapped air and ensure good adhesion, and then the tape was peeled off vertically. The degree of peeling of the coating film was evaluated as follows according to the ASTM-D3359 standard. The results are shown in Tables 1 to 3. (Evaluation criteria for peel adhesion) A: Rating 5B to 4B, excellent adhesion B: The rating is 5B to 4B, but the coating film has undergone cohesive failure and part of the coating film on the surface side has come off. C: Rating 3B or lower, poor adhesion

[0106] [(3) Evaluation of temperature dependence of wiring resistance] This evaluation shows that the resistance (R T80 ) and resistance at 20°C (R T20 ) and the ratio (R T80 / R T20 ) was obtained. T80 , R T20 Both are resistance values ​​per 1 cm of wiring. The specific steps are shown below. A measurement coupon was cut out to a length of 140 mm and a width of 10 mm so that the center of the conductive layer of the linear pattern having a line width of 1 mm, a length of 120 mm, and a thickness of 10 μm formed on the conductive laminate for heaters of Examples 1 to 26 and Comparative Examples 1 to 4 was located in the middle. On the side of the measurement coupon opposite the conductive layer, 13 lines perpendicular to the pattern were drawn at 1 cm intervals with oil-based marker from the longitudinal end of the conductive layer to the conductive layer as marks. Next, in a temperature-controlled room controlled at 20°C, the resistance value was measured using a tester between two points 10 cm apart by the marks, and the resistance per cm of wiring at 20°C (R T20The measurement coupon was placed on a hot plate maintained at a measured temperature of 80° C. for 2 minutes to stabilize the temperature. The resistance (R T20 ) and calculate the resistance per 1 cm of wiring at 80°C (R T80 ) and the resistance at 20°C (R T20 ) and the ratio (R T80 / R T20 The resistance ratio (R T80 / R T20 The lower the value of the ΔE, the less the heat generation will slow down when the temperature rises due to self-heating, and the more excellent the device is in terms of the potential for power saving. The results are shown in Tables 1 to 3.

[0107] [(4) Hot stretching evaluation 1] This evaluation yielded the breaking elongation in an atmosphere at 160° C. The specific procedure is as follows. First, copper foil tape having a conductive adhesive layer was attached onto the conductive layer of each of the measurement coupons of Examples 1 to 26 and Comparative Examples 1 to 4 at two locations spaced 10 cm apart based on the marks on the back surface of the coupons. After that, two lead wires were electrically connected to the copper foil tape at the two locations via alligator clips. The measurement coupon with the lead wires connected was clamped at a distance of 10 cm between the test wires in a tensile tester with a heating oven at 160°C, and the oven was closed. The resistance between the lead wires pulled out of the heating oven was measured with a tester while the tester was used to stretch the test wires at a constant speed in the longitudinal direction at a pulling speed of 10 mm / min up to an elongation rate of 300%, and the elongation rate at which the resistance value became unmeasurable (100 MΩ or more) was taken as the breaking elongation rate. The higher the breaking elongation rate, the better it is because it is possible to deal with complex shapes that are more severely drawn during molding. The results are shown in Tables 1 to 3.

[0108] The elongation rate is a value calculated as follows. (Elongation rate) [%] = {(length after stretching - length before stretching) / (length before stretching)} x 100

[0109] [(5) Hot stretching evaluation 2] This evaluation revealed that the rate of change in the resistance value of the conductive layer (R 40 ) and the rate of change in the resistance of the conductive layer when the elongation rate is 80% (R 80 ) and the ratio (R 80 / R 40 The specific steps are as follows: Two of the measurement coupons for each of the above Examples 1 to 26 and Comparative Examples 1 to 4 were prepared, and one of them was stretched to an elongation rate of 40% in a heating oven at 160°C with a gripping length of 10 cm and a pulling speed of 10 mm / min in the longitudinal direction. The other was similarly stretched to an elongation rate of 80% in a heating oven at 160°C with a gripping length of 10 cm and a pulling speed of 10 mm / min in the longitudinal direction. After removing each from the oven and cooling to 20°C, the resistance value between positions spaced 10 cm apart based on the marks made before stretching was measured in the same manner as in the measurement described in (3) above, and the resistance value was divided by 10 to calculate the resistance (Ω) after stretching at each predetermined elongation rate per 1 cm of wiring before stretching. Next, the ratio before and after stretching was calculated using the resistance per 1 cm of wiring at each elongation rate, and this was used as the rate of change in resistance value at each elongation rate. The rate of change in resistance at an elongation rate of 40% during hot stretching (R 40 ) and the rate of change in resistance at 80% elongation (R 80 ) and the resistance ratio (R 80 / R 40 The resistance ratio (R 80 / R 40 The lower the value of the θ is, the higher the in-plane heat generation uniformity of the heater is, and the more excellent the heater is because no specific part generates excessive heat. The results are shown in Tables 1 to 3.

[0110] [Evaluation of three-dimensional molded heaters and molded heaters] Hereinafter, in (6) to (11), the procedure for evaluating the heat generation uniformity of the three-dimensional molded heater and the molded heater will be described, including the manufacturing procedure for each heater.

[0111] [(6) Heat generation evaluation of three-dimensional molded heaters 1] In the conductive laminates for heaters of Examples 1 to 26 and Comparative Examples 1 to 4, a hemispherical metal mold that had been previously peeled and had a radius of 4 cm was placed facing the conductive layer side so that the center of the conductive layer position of the linear pattern with a line width of 1 mm, length of 120 mm, and thickness of 10 μm overlapped with the zenith, and overlay molding was performed at a set temperature of 160° C. using a TOM molding machine (manufactured by Fuse Vacuum Co., Ltd.). As a result, a three-dimensional molded heater was obtained, which had a conductor on the inside, and only the area up to 4 cm on both sides from the center of the conductive layer position was molded into a hemispherical shape before molding, and the area of ​​2 cm from both ends of the conductive layer was flat without deformation. Copper foil tapes with a conductive adhesive layer were attached to the three-dimensional molded heater at positions 1 cm from both ends of the conductive layer pattern toward the center of the pattern on the conductive layer, in a direction in which the conductive adhesive layer and the conductive layer are in contact with each other. The distance between the two points where the copper foil tape was attached corresponds to a distance of 10 cm on the conductive layer before molding. Next, two lead wires were connected to the positive and negative poles of a power supply (E36103, manufactured by Keysight Technologies) via alligator clips to the copper foil tape at the two locations, allowing a predetermined voltage to be applied to the conductive layer. In addition, the tips of two thermocouple terminals were attached and fixed with polyimide tape to the opposite surface of the conductive layer pattern at the zenith of the hemisphere and the rising part from the flat surface. Next, each of the thermocouples was connected to a temperature logger (PicoLog TC-08, manufactured by Pico Technology), allowing the temperature data of the two locations to be acquired. Next, while the temperature data of the two locations was acquired by the temperature logger, a voltage of 10 V was applied from the power supply device to the three-dimensional molding heater, and the temperature difference between the two locations one minute after the voltage application was evaluated according to the following criteria. The results are shown in Tables 1 to 3. (Temperature difference measured 1 minute after voltage application) A: The temperature difference is less than 5°C, and the heater has excellent heat generation uniformity for practical use. B: The temperature difference is between 5°C and 10°C. The heater has uneven heat generation but is not a problem for practical use. C: The temperature difference is 10°C or more, and there is temperature unevenness that is problematic for practical use of the heater.

[0112] [(7) Heat generation evaluation of three-dimensional molded heaters 2] A three-dimensional heater obtained in the same manner as in the above [(6) Heat generation evaluation 1 of a three-dimensional heater molded into a three-dimensional shape] was used, except that the shape of the metal mold was a spherical indentation with a height of 1 cm and a radius of 4 cm. Similarly to the above [(6) Heat generation evaluation 1 of a three-dimensional heater molded into a three-dimensional shape], a voltage was applied to the three-dimensional heater and the temperature was measured, and the temperature difference measured one minute after the voltage was applied was evaluated according to the following criteria. The results are shown in Tables 1 to 3. (Temperature difference measured 1 minute after voltage application) A: The temperature difference is less than 5°C, and the heater has excellent heat generation uniformity for practical use. B: The temperature difference is between 5°C and 10°C. The heater has uneven heat generation but is not a problem for practical use. C: The temperature difference is 10°C or more, and there is temperature unevenness that is problematic for practical use of the heater.

[0113] [(8) Heat generation evaluation of molded heaters produced by overlay molding 1] In the above, [(6) Heat generation evaluation 1 of a three-dimensional molded heater molded into a three-dimensional shape], a molded heater was prepared by integrating a conductive laminate for heaters with an ABS resin molded product in the same manner as above, except that the metal mold was replaced with a hemispherical ABS resin molded product with a radius of 4 cm. In addition, the molded heater was flat within 2 cm from both ends of the conductive layer, as in the above [(6) Heat generation evaluation 1 of a three-dimensional molded heater molded into a three-dimensional shape], and was not integrated with the molded product. Next, voltage was applied to the molded heater and temperature was measured in the same manner as in the above [(6) Heat generation evaluation 1 of a three-dimensional molded heater molded into a three-dimensional shape], and the temperature difference measured 1 minute after the voltage was applied was evaluated according to the following criteria. The results are shown in Tables 1 to 3. (Temperature difference measured 1 minute after voltage application) A: The temperature difference is less than 5°C, and the heater has excellent heat generation uniformity for practical use. B: The temperature difference is between 5°C and 10°C. The heater has uneven heat generation but is not a problem for practical use. C: The temperature difference is 10°C or more, and there is temperature unevenness that is problematic for practical use of the heater.

[0114] [(9) Heat generation evaluation of molded heaters produced by overlay molding 2] A molded heater was obtained in the same manner as in the above [(8) Heat generation evaluation 1 of molded body by overlay molding], except that the shape of the ABS resin molded body was a spherical indentation with a height of 1 cm and a radius of 4 cm. Next, a voltage was applied to the molded heater and the temperature was measured in the same manner as in the above [(6) Heat generation evaluation 1 of three-dimensional molded heater molded into a three-dimensional shape], and the temperature difference measured one minute after the voltage application was evaluated according to the following criteria. The results are shown in Tables 1 to 3. (Temperature difference measured 1 minute after voltage application) A: The temperature difference is less than 5°C, and the heater has excellent heat generation uniformity for practical use. B: The temperature difference is between 5°C and 10°C. The heater has uneven heat generation but is not a problem for practical use. C: The temperature difference is 10°C or more, and there is temperature unevenness that is problematic for practical use of the heater.

[0115] [(10) Heat generation evaluation of molded heaters produced by film insert molding 1] As in the above [(6) Heat generation evaluation 1 of a film molded body molded into a three-dimensional shape], a conductive laminate for a heater was molded, and the molded conductive laminate for a heater was set inside an injection molding machine equipped with a valve gate type in-mold molding test mold, and then PC / ABS resin was injection molded to obtain a molded heater in which the conductive laminate for a heater and a PC / ABS resin molded product were integrated. As in the above [(6) Heat generation evaluation 1 of a three-dimensional molded heater molded into a three-dimensional shape], the molded heater was flat within 2 cm from both ends of the conductive layer and was not integrated with the molded product. Next, voltage was applied to the molded heater and temperature was measured in the same manner as in the above [(6) Heat generation evaluation 1 of a three-dimensional molded heater molded into a three-dimensional shape], and the temperature difference measured 1 minute after the voltage was applied was evaluated according to the following criteria. The results are shown in Tables 1 to 3. (Temperature difference measured 1 minute after voltage application) A: The temperature difference is less than 5°C, and the heater has excellent heat generation uniformity for practical use. B: The temperature difference is between 5°C and 10°C. The heater has uneven heat generation but is not a problem for practical use. C: The temperature difference is 10°C or more, and there is temperature unevenness that is problematic for practical use of the heater. The conditions for manufacturing the molded heater are as follows. The injection molding machine used was a Toshiba Machine IS170 (i5) equipped with a test mold designed to obtain a molded product of the same shape as the hemispherical metal mold used in molding the conductive laminate for the heater. The PC / ABS resin used was LUPOYPC / ABSHI5002 manufactured by LG Chem. The injection conditions were a screw diameter of 40 mm, a cylinder temperature of 260°C, a mold temperature (fixed side, movable side) of 60°C, an injection pressure of 160 MPa (80%), a holding pressure of 100 MPa, an injection speed of 60 mm / sec (28%), an injection time of 4 seconds, and a cooling time of 20 seconds.

[0116] [(11) Heat generation evaluation of molded heaters produced by film insert molding 2] As in the above [(7) Heat generation evaluation 2 of a three-dimensional molded heater molded into a three-dimensional shape], a conductive laminate for heaters was molded, and the shape of the test mold in the above [(10) Heat generation evaluation 1 of a molded heater by film insert molding] was changed to a shape that would give a spherically-defected molded product with a height of 1 cm and a radius of 4 cm, the same as the metal mold used in the above (7). In the same manner as the above [(10) Heat generation evaluation 1 of a molded heater by film insert molding], injection molding was performed to obtain a molded heater. Next, voltage was applied to the molded heater and temperature was measured in the same manner as the above [(6) Heat generation evaluation 1 of a three-dimensional molded heater molded into a three-dimensional shape], and the temperature difference measured 1 minute after the voltage was applied was evaluated according to the following criteria. The results are shown in Tables 1 to 3. (Temperature difference measured 1 minute after voltage application) A: The temperature difference is less than 5°C, and the heater has excellent heat generation uniformity for practical use. B: The temperature difference is between 5°C and 10°C. The heater has uneven heat generation but is not a problem for practical use. C: The temperature difference is 10°C or more, and there is temperature unevenness that is problematic for practical use of the heater.

[0117] [Table 1]

[0118] [Table 2]

[0119] [Table 3]

[0120] [Summary of results] The conductive laminates for heaters of Comparative Examples 1 to 4 were evaluated for (4) the breaking elongation rate in an atmosphere at 160° C., and (5) the rate of change in the resistance value of the conductive layer when the elongation rate was set to 40% (R 40 ) and the rate of change in the resistance of the conductive layer when the elongation rate is 80% (R 80 ) and the ratio (R 80 / R 40 ) was not within the prescribed range, and the evaluations of (6) to (11) for the three-dimensionally molded heater and the molded body heater were low, ranging from B to C, resulting in problems in practical use. That is, it became clear that when the conductive laminates for heaters of Comparative Examples 1 to 4 were used as heaters molded into three-dimensional shapes including three-dimensional curved surfaces, uneven heat generation occurred according to differences in the degree of deformation depending on the part, resulting in large differences in the temperature reached with heat generation, and the required heating performance could not be obtained. Furthermore, among Comparative Examples 1 to 4, in addition to the above (4) and (5), the above (3) resistance per 1 cm of wiring at 80° C. (R T80 ) and the wiring resistance at 20°C (R T20 ) and the ratio (R T80 / R T20In Comparative Example 4, in which the values ​​of (6) to (11) were not within the predetermined range, the evaluations of all of the above items (6) to (11) were C, which was a level that caused practical problems, and the performance was even lower than that of Comparative Examples 1 to 3. The results of Comparative Example (4) show that when the temperature rises due to self-heating, the distance between the conductive particles increases due to thermal expansion of the conductive layer, the conductivity decreases, and the resistance value increases significantly. In other words, when used as a heater formed into a three-dimensional shape including a three-dimensional curved surface, the heat generation may be significantly reduced in the area where the temperature becomes locally high during current application due to non-uniform heat generation. Therefore, it is clear that the conductive laminate for heaters of Comparative Example 4 has even lower performance than the conductive laminates for heaters of Comparative Examples 1 to 3, and is not practically usable.

[0121] On the other hand, (3) R T80 / R T20 , (4) Breaking elongation rate, (5) R 80 / R 40 In the conductive laminates for heaters of Examples 1 to 13 and 16 to 26, in which all of (6) to (11) are within the specified range, the evaluations of (6) to (11) were all B to A, showing excellent heat generation uniformity. Even in Examples 14 and 15, in which only (3) is not within the specified range, the evaluations of (6) to (11) are all only B, and although the performance is somewhat lower than that of Examples 1 to 13 and 16 to 26 in which all of (3) to (5) are within the specified range, it has reached a level that is not problematic in practical use. That is, all of the conductive laminates for heaters of Examples 1 to 26, when used as a heater after being molded into a three-dimensional shape including a three-dimensional curved surface, suppress unevenness in heat generation due to differences in the degree of deformation, that is, good heat generation uniformity regardless of the degree of deformation, and also suppress a significant decrease in local heat generation due to local thermal expansion, and therefore clearly show that they function as an extremely excellent heater in terms of heat generation and safety. In particular, (5) R 80 / R 40The fact that (5) is within the specified range of 5 or less means that the difference in the rate of change in resistance value due to the elongation rate is small when the conductive layer is deformed. In other words, it is considered that the fact that (5) is within the specified range suppresses the change in the resistance value of the entire heater after molding, stabilizes the resistance value of the entire heater, and therefore enables the realization of high heat generation uniformity. In addition, it is presumed that this tendency is more remarkable as a result of the fact that the flake-shaped conductive fine particles having a relatively high aspect ratio of the present invention, the chain-like conductive fine particles, and the crosslinking agent are used in combination, and the connection network between the conductive powders and the matrix resin surrounding them have deformation followability and moderate fixation during molding, thereby suppressing the change in resistance value due to elongation stress and thermal stress during molding, and the fluctuation in the spacing between the conductive fine particles due to the thermal expansion of the matrix resin during self-heating.

[0122] In this way, the three-dimensional molded heater and molded heater using the conductive laminate for heaters of the present invention make it possible to directly fabricate lightweight, space-saving heaters without compromising design freedom into plastic housings and three-dimensional shaped parts of home appliances, automobile parts, robots, etc. This makes it possible to provide a space-saving and simple heating mechanism for parts of devices and appliances with shapes and locations that have been difficult to implement until now, which ultimately contributes to high added value such as good usability and energy savings for the devices. [Explanation of symbols]

[0123] 1 Board 2 Conductive layer 3 Decorative layer 4 Connection pins 10. Conductive laminate for heater 11 Mold 12 Injection mold 13 Opening 14 Injection 15 Increase 16 Pressurization 20 Molded objects 21 Upper chamber box 22 Lower chamber box 30 Three-dimensional molded heater 40 Molded body heater

Claims

1. A conductive laminate for a heater that is formed into a three-dimensional shape including an uneven surface or a three-dimensional curved surface, The conductive laminate for a heater has a substrate containing a thermoplastic resin and a conductive layer, the conductive layer is a cured product of a conductive composition containing a resin (A) and conductive fine particles (B), The conductive laminate for a heater, wherein the conductive layer satisfies the following (1) and (2): (1) The breaking elongation in an atmosphere of 160° C. is 90 to 300%. (2) The rate of change in the resistance value of the conductive layer when the elongation rate is 40% in an atmosphere of 160° C. (R ４０ ) and the rate of change in the resistance value of the conductive layer when the elongation rate is 80% (R ８０ ) and the ratio (R ８０ / R ４０ ) is 5.0 or less.

2. The resistance value (R Ｔ８０ ) and the resistance value per cm in an atmosphere at 20°C (R Ｔ２０ ) and the ratio (R Ｔ８０ / R Ｔ２０ 2. The conductive laminate for heaters according to claim 1, wherein the coefficient of friction coefficient is 2.0 or less.

3. 2. The conductive laminate for a heater according to claim 1, wherein the conductive fine particles (B) include flake-shaped conductive fine particles (B1) having an aspect ratio of 20 to 80.

4. 4. The conductive laminate for a heater according to claim 3, wherein the conductive fine particles (B) further contain chain-spherical conductive fine particles (B2).

5. 2. The conductive laminate for heaters according to claim 1, wherein the conductive fine particles (B) comprise one or more kinds of conductive fine particles selected from the group consisting of silver powder, copper powder, silver-coated powder, copper alloy powder, conductive oxide powder, and carbon fine particles.

6. The conductive laminate for a heater according to claim 1 , wherein the conductive composition further comprises a crosslinking agent (C).

7. The conductive laminate for heaters according to claim 6 , wherein the crosslinking agent (C) comprises a trifunctional blocked isocyanate crosslinking agent.

8. 2. The conductive laminate for heaters according to claim 1, wherein the content of the resin (A) is 8 to 40 mass % in the solid content of the conductive composition.

9. 2. The conductive laminate for a heater according to claim 1, wherein the substrate comprises a film selected from the group consisting of polycarbonate, polymethyl methacrylate, polypropylene, and polyethylene terephthalate, or a laminate film thereof.

10. A three-dimensionally molded heater, comprising the conductive laminate for a heater according to any one of claims 1 to 9 molded into a three-dimensional shape including an uneven surface or a three-dimensional curved surface.

11. A step of disposing the conductive laminate for a heater according to any one of claims 1 to 9 on a molded article; and integrating the conductive laminate for heaters and the molded article by an overlay molding method.

12. A step of forming the conductive laminate for a heater according to any one of claims 1 to 9 into a three-dimensional shape including an uneven surface or a three-dimensional curved surface; placing the molded conductive laminate for a heater in a mold for injection molding; A method for manufacturing a molded heater, comprising the steps of: molding a thermoplastic resin by injection molding to form a molded product; and integrating the conductive laminate for a heater with the molded product containing a thermoplastic resin.

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