Film forming composition, film, circuit sheet, and sensor sheet

Abstract

A film that protects circuit wiring or a sensor electrode of a circuit sheet or a sensor sheet is formed, said protective film having been made thinner and having a superior ability to protect the circuit wiring or the sensor electrode. Additionally, a film forming composition that is for forming said film is obtained. The film forming composition includes a cycloolefin polymer, a physical property adjustment material, and a solvent. The film comprises said film forming composition.

Description

Film-forming composition, film, circuit sheet, and sensor sheet

[0001] The present invention relates to a coating that can be used as a protective layer for a circuit sheet, a film-forming composition that forms the coating, and a circuit sheet and a sensor sheet that include the coating.

[0002] The conductive wires arranged on the circuit sheet or the sensor electrodes arranged on the sensor sheet may be formed from a silver paste containing silver or a transparent conductive polymer called PEDOT / PSS. A highly transparent protective layer is provided on the surface of the circuit sheet or the sensor sheet to protect the conductive wires or sensor electrodes from breakage, corrosion, etc.

[0003] However, silver paste or transparent conductive polymers are susceptible to deterioration due to water vapor, ultraviolet light, etc., and sulfurization due to sulfur gas, etc. Therefore, it is desirable for the protective layer to have properties that make these phenomena less likely to occur. A technology for covering conductive wires with a protective layer is described, for example, in Japanese Patent No. 6167103 (Patent Document 1).

[0004] Patent No. 6167103

[0005] Due to the demand for thinner and cheaper circuit sheets or sensor sheets, the protective layer is required to be thinner and have improved protective performance.

[0006] One aspect of the present invention is a film-forming composition containing a cycloolefin polymer, a physical property adjuster, and a solvent. According to one aspect of the present invention, the inclusion of a cycloolefin polymer allows for the formation of a film with excellent transparency and robustness. Furthermore, the inclusion of a physical property adjuster in the film-forming composition allows for the formation of a film with improved printability, quality, and the like. Furthermore, the inclusion of a solvent in the film-forming composition allows for the formation of a film by a technique such as printing.

[0007] In one aspect of the present invention, the cycloolefin polymer is a ring-opening polymer of cycloolefins or a copolymer of cycloolefins and an olefin. According to this aspect of the present invention, the film-forming composition can form a film having excellent transparency and robustness.

[0008] One aspect of the present invention is a film-forming composition in which the cycloolefin polymer has a polar group on the cyclo ring. According to this aspect of the present invention, the cycloolefin polymer is easily soluble in a highly polar solvent. Furthermore, a highly polar substance can be contained in the film-forming composition at a high concentration as a property adjusting agent.

[0009] In one aspect of the present invention, the physical property adjusting agent is at least one of a printability improving agent and a film quality improving agent, thereby improving at least one of the printability and film quality of the film-forming composition.

[0010] One aspect of the present invention is a film-forming composition containing 0.1 to 30 volume % of the physical property adjusting agent, which can avoid the risk of deterioration in printability and film quality.

[0011] In one aspect of the present invention, the film-forming composition includes a property-adjusting agent having a polar group selected from a hydroxyl group, an amino group, a carbonyl group, a carboxyl group, a nitro group, a sulfo group, an ester group, an amide group, or a halogen group. Because the property-adjusting agent has a polar group selected from a hydroxyl group, an amino group, a carbonyl group, a carboxyl group, a nitro group, a sulfo group, an ester group, an amide group, or a halogen group, the film-forming composition can have improved adhesion, bondability, or miscibility with the target object.

[0012] In one aspect of the present invention, the film-forming composition includes a physical property adjusting agent having a reactive functional group selected from an epoxy group, a methacryl group, a vinyl group, a mercapto group, and an amino group. Since the physical property adjusting agent has a reactive functional group selected from an epoxy group, a methacryl group, a vinyl group, a mercapto group, and an amino group, the film-forming composition can have improved adhesion to a substrate sheet, circuit wiring, or the like to which it is applied.

[0013] One aspect of the present invention is a film made from any of the film-forming compositions described above. According to this aspect of the present invention, a film having excellent transparency, durability, and film quality can be realized.

[0014] One aspect of the present invention is a circuit sheet having a base sheet, circuit wiring, and a protective layer formed of a film made of any of the film-forming compositions described above. According to this aspect of the present invention, the protective layer is a film made of any of the film-forming compositions described above, so the circuit sheet provides excellent protection for the circuit wiring sandwiched between the base sheet and the protective layer.

[0015] One aspect of the present invention is a circuit sheet having a three-dimensional shape with curved surfaces. According to this aspect of the present invention, the circuit sheet can be formed to better fit the space in which it is to be used, thereby increasing the degree of freedom in designing devices that use the circuit sheet.

[0016] One aspect of the present invention is a sensor sheet having a base sheet, circuit wiring, sensor electrodes, and a protective layer formed of a film made of any of the film-forming compositions. According to this aspect of the present invention, the sensor sheet has a protective layer formed of a film made of any of the film-forming compositions, and therefore the sensor sheet can provide excellent protection for the circuit wiring and sensor electrodes sandwiched between the base sheet and the protective layer.

[0017] One aspect of the present invention is a sensor sheet having a three-dimensional shape with curved surfaces. According to this aspect of the present invention, the sensor sheet can be formed to better fit the space in which it is to be used, thereby increasing the degree of freedom in designing devices that use the sensor sheet.

[0018] According to one aspect of the present invention, a film-forming composition having printability can be provided. According to one aspect of the present invention, a film having excellent protective performance can be provided. According to one aspect of the present invention, a circuit sheet or a sensor sheet having a film having excellent protective performance can be provided.

[0019] 1A and 1B are schematic diagrams of a circuit sheet according to one embodiment of the present invention, with Fig. 1A being a front view and Fig. 1B being a plan view. 2A and 2B are schematic diagrams of a sensor sheet according to one embodiment of the present invention, with Fig. 2A being a front view and Fig. 2B being a plan view. 3A and 3B are schematic diagrams of a sensor sheet according to another embodiment of the present invention, with Fig. 3A being a cross-sectional view taken along line IIIA-IIIA in Fig. 3B and Fig. 3B being a plan view.

[0020] An example of an embodiment according to one aspect of the present invention will be described below with reference to the drawings. The aspect and embodiment described below do not unduly limit the content of the present invention described in the claims, and not all of the configurations described in this embodiment are necessarily essential as a solution to the present invention.

[0021] When the terms "first" and "second" are used in this specification and claims, they are used to distinguish between different components, and are not used to indicate a specific order, superiority, or inferiority, etc. Furthermore, components that are common to the embodiments and that have the same effects are assigned the same reference numerals, and redundant explanations are omitted.

[0022] <Film-forming composition> The film-forming composition described in this embodiment is applied to a substrate sheet such as a circuit sheet or a sensor sheet to serve as a protective layer for protecting circuit wiring (conductive wires) or sensor electrodes, and has high transparency and excellent protective performance for the object to be coated. The film-forming composition contains a cycloolefin polymer, a property adjuster, and a solvent. The composition of the film-forming composition will be described below.

[0023] Cycloolefin polymer: When dissolved in a solvent, cycloolefin polymers have high cohesive strength and tend to form strings when used as coating liquids such as printing inks, making them generally unsuitable for printing. Furthermore, they have poor adhesion to resin films such as PET, which serve as substrate sheets, and are prone to peeling. Therefore, although cycloolefin polymers are sometimes used as preformed plates, they are hardly suitable binder resins for printing, and are difficult to use as coating liquids. However, because cycloolefin polymers are amorphous, they have high transparency and low birefringence. Furthermore, because they have an alicyclic structure, they have a high glass transition temperature Tg and excellent heat resistance and robustness. Furthermore, because they have a hydrocarbon structure with few polar groups, they have low moisture absorption and also excellent light resistance and chemical resistance. Therefore, the present inventors investigated how this cycloolefin polymer could be used as a binder resin for coating materials.

[0024] Cycloolefin polymers are polymers having an alicyclic structure in the polymer main chain, and examples thereof include COP resins and COC resins obtained by polymerizing cycloolefins. COP resins are ring-opening polymers of cycloolefins or hydrogenated products thereof, such as norbornene, tetracyclododecene, or derivatives thereof. COC resins are cycloolefin copolymers, which are copolymers of cyclic olefins and olefins, and examples thereof include copolymers in which a cyclopentyl residue or a substituted cyclopentyl residue is inserted into the molecular chain by polymerization of a cycloolefin such as norbornene, tetracyclododecene, or a derivative thereof with ethylene or propylene.

[0025] The cycloolefin used as a raw material for the cycloolefin polymer may be monocyclic or polycyclic. Thermoplastic norbornene-based resins or thermoplastic tetracyclododecene-based resins are preferred because they have excellent adhesion to substrate sheets or circuit wiring and can be obtained by drying and curing without the need for high-temperature heating when forming a film from the film-forming composition. Examples of thermoplastic norbornene-based resins include ring-opening polymers of norbornene-based monomers, hydrogenated products thereof, addition polymers of norbornene-based monomers, and addition polymers of norbornene-based monomers and olefins. Examples of thermoplastic tetracyclododecene-based resins include ring-opening polymers of tetracyclododecene-based monomers, hydrogenated products thereof, addition polymers of tetracyclododecene-based monomers, and addition polymers of tetracyclododecene-based monomers and olefins.

[0026] As mentioned above, a hydrocarbon structure with few polar groups leads to reduced hygroscopicity. However, from the viewpoint of improving adhesion, adhesiveness, and miscibility, it is a preferred embodiment to use a cycloolefin polymer having a polar group in the cyclo ring. Cycloolefin polymers having such polar groups are preferred because they have good solubility in highly polar solvents such as ethyl acetate and butyl acetate, and can accommodate a wider variety of compatible property adjusters and increase the amount of blended. The cycloolefin polymer may have functional groups such as hydroxyl groups, amino groups, carbonyl groups, carboxyl groups, nitro groups, sulfo groups, ester groups, and amide groups. Reactive functional groups such as epoxy groups, methacrylic groups, vinyl groups, mercapto groups, and amino groups can improve the adhesion of the film-forming composition to the substrate sheet or circuit wiring to be coated.

[0027] Commercially available cycloolefin polymers include, for example, Zeonex (registered trademark, manufactured by Zeon Corporation), Zeonor (registered trademark, manufactured by Zeon Corporation), and Arton (registered trademark, manufactured by JSR Corporation) for COP resins, and APEL (registered trademark, manufactured by Mitsui Chemicals, Inc.) and TOPAS (registered trademark, manufactured by Polyplastics Co., Ltd.) for COC resins.

[0028] The amount of cycloolefin polymer in the film-forming composition can be 5 to 70% by volume, preferably 35 to 60% by volume. If the amount of cycloolefin polymer in the film-forming composition is less than 5% by volume, it becomes difficult to achieve the desired thickness. If the amount exceeds 70% by volume, the viscosity becomes too high, resulting in poor printability. If the amount is 35 to 60% by volume, the film-forming composition has good printability.

[0029] Solvent: The solvent dissolves or disperses the cycloolefin polymer and imparts an appropriate viscosity to the solution or dispersion, thereby producing a mixed composition with properties suitable for a coating liquid. Examples of such solvents include hydrocarbon, aromatic, ether, and ketone organic solvents. More specific examples include pentane, hexane, octane, cyclohexane, methylcyclohexane, ethylcyclohexane, 1,2-dimethylcyclohexane, cyclohexene, benzene, toluene, xylene, ethyl ether, tetrahydrofuran, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone (MIBK), and isophorone. For COP resins or COC resins having polar groups in the molecular chain, such as cyclocyclic rings, ester solvents such as ethyl acetate, butyl acetate, hexyl acetate, and dihydroterpinyl acetate can be used. High-boiling point solvents are preferred because they improve printability.

[0030] The amount of solvent to be blended is the balance other than the cycloolefin polymer and the property adjusting agent, and can be approximately 25 to 90% by volume, preferably 35 to 60% by volume, of the film-forming composition. If the amount of solvent to be blended in the film-forming composition is less than 25% by volume, the non-volatile components will be too high, resulting in poor printability. If the amount to be blended exceeds 90% by volume, the non-volatile components will be too low, making it difficult to achieve the desired thickness. If the amount to be blended is 35 to 60% by volume, the film-forming composition will have suitable printability.

[0031] Physical property adjuster: A physical property adjuster is added to a liquid material in which a cycloolefin polymer is dissolved or dispersed, thereby imparting properties to the liquid material that cannot be obtained by simply dissolving or dispersing the polymer. By adding a physical property adjuster to the cycloolefin polymer, rather than just dissolving or dispersing it in a solvent, the cycloolefin polymer can be used as a binder resin for coating materials such as printing inks.

[0032] Examples of physical property adjusters include printability improvers that improve printability, viscosity adjusters such as plasticizers that adjust viscosity, thixotropy-imparting agents that impart thixotropy, foam inhibitors such as antifoaming agents that suppress foaming during printing, stringing inhibitors that suppress stringing, wettability improvers that prevent repellency on the printing substrate and prevent the occurrence of print unevenness and mottled patterns, cutting improvers that enable continuous printing, and coating liquid stabilizers such as silane coupling agents, polymerization inhibitors, or antioxidants that stabilize the properties of the film-forming composition.

[0033] Further examples of physical property adjusters include film quality improvers that improve film quality, such as smoothing agents that improve the surface smoothness of the resulting film, from the perspective of improving the quality of the film itself. Furthermore, from the perspective of the film functioning as a protective layer and protecting the quality of the conductive parts it covers, examples include moisture resistance improvers that improve moisture resistance, sulfurization resistance improvers that improve sulfurization resistance, gas barrier improvers that suppress gas permeability such as oxygen, heat resistance improvers that improve heat resistance, light resistance improvers that prevent discoloration, ultraviolet inhibitors that suppress ultraviolet transmission, and adhesion improvers that improve adhesion to the substrate sheet. Among these, moisture resistance improvers, sulfurization resistance improvers, gas barrier improvers, heat resistance improvers, light resistance improvers, and ultraviolet inhibitors, from the perspective of a protective layer, are included in weather resistance improvers. These can also be considered names that express the functionality of barrier improvers.

[0034] Examples of physical property adjusters include petroleum hydrocarbons such as aromatic, paraffinic, and naphthenic hydrocarbons; polyolefins such as polyethylene, polypropylene, polybutene, liquid polyisobutylene, liquid polybutene, and hydrogenated liquid polyisoprene, as well as their derivatives; petroleum asphalts; and other materials. Alternatively, examples of physical property adjusters include polyolefins such as halogenated or acid-modified maleic anhydride-chain-modified polypropylenes with carboxylic acids such as maleic acid. These materials improve printability and film quality, such as weather resistance. These materials can be used singly or in combination.

[0035] Physical property adjusters having polar groups such as hydroxyl, amino, carbonyl, carboxyl, nitro, sulfo, ester, amide, and halogen groups are adhesion improvers that contribute to improving the adhesion of the film-forming composition to the substrate sheet, circuit wiring, etc. that are to be coated. Physical property adjusters having reactive functional groups such as epoxy, methacrylic, vinyl, mercapto, and amino groups contribute to improving the adhesion of the film-forming composition to the substrate sheet, circuit wiring, etc. that are to be coated.

[0036] Functional fillers such as titanium oxide or zinc oxide function as film quality improvers, such as moisture resistance improvers that suppress water vapor permeability, ultraviolet inhibitors that suppress ultraviolet transmission, sulfuration resistance improvers that suppress sulfur gas permeability, or gas barrier improvers, etc. In addition, they also function as printability improvers, such as viscosity adjusters, foam inhibitors, or thixotropic agents.

[0037] The amount of the physical property adjuster in the film-forming composition can be 0.1 to 30% by volume, preferably 0.5 to 25% by volume, and more preferably 3 to 20% by volume. In one embodiment, the amount of the physical property adjuster in the film-forming composition is 0.1 to 15% by volume, and in a preferred embodiment, it is 3 to 10% by volume. This is because printability deteriorates when the amount of the physical property adjuster is less than 0.1% by volume, and film quality may deteriorate when the amount exceeds 30% by volume. A blending amount of 3 to 20% by volume provides favorable printability and enables the formation of a high-quality film.

[0038] Preparation of film-forming composition: The film-forming composition is prepared by dissolving or dispersing the cycloolefin polymer in a solvent, adding a property-adjusting agent, and mixing. The resulting film-forming composition preferably has a viscosity of 1 to 300 Pa·s, as measured using a rotational viscometer at a rotational speed of 10 rpm and 25°C. If the viscosity of the film-forming composition is less than 1 Pa·s, the shape retention of the patterned circuit wiring may be reduced. If the viscosity exceeds 300 Pa·s, clogging may occur easily during screen printing, a typical application method, which may reduce productivity.

[0039] The film-forming composition described above has an appropriate viscosity and is suitable for printing on a substrate sheet. Furthermore, the film-forming composition is less likely to produce pinholes during application, such as printing, and can form a smooth film. Furthermore, once the film-forming composition hardens, it can form a high-quality film that can serve as a protective layer.

[0040] Formation of film: The film-forming composition can be applied to a substrate sheet made of a resin film or the like by screen printing or the like, and solidified to form a film that can function as a protective layer for the substrate sheet. Due to the properties of the cycloolefin polymer, the protective layer can be a highly transparent film, and the average light transmittance of the protective layer in the visible light range of 400 nm to 800 nm can be preferably 80% or more, more preferably 85% or more. In addition to screen printing, other application methods that can be used include spray coating, coater printing, transfer printing, and dipping.

[0041] The thickness of the coating serving as a protective layer to protect the circuit wiring or sensor electrodes can be 0.5 to 50 μm, preferably 3 to 30 μm, and more preferably 6 to 8 μm. This is because, although the thickness of the coating serving as a protective layer can be greater than 10 μm, this would be contrary to the demand for thinner films. Furthermore, if the thickness of the coating is less than 3 μm, the protection of the circuit wiring or sensor electrodes may be inadequate. Furthermore, the thickness can be increased by stacking the coatings. This makes it possible to thicken the coating to approximately 100 μm.

[0042] The coating has excellent moisture resistance, light resistance, and sulfuration resistance, low reactivity to chemicals, solvent barrier properties, low volatility and no bleeding, and is non-migratory to other components that adhere to the surface of the coating, non-resistance to resin attack, and minimal contamination of these other components.

[0043] <Circuit Sheet> An embodiment of a protective layer formed from a film-forming composition is shown in the front view of Fig. 1A and the plan view of Fig. 1B. The circuit sheet 10 shown in these figures is formed by applying the film-forming composition to a base sheet 11 so as to cover conductive wires 12, forming a protective layer 13. In these figures, only one conductive wire 12 that forms the circuit is shown schematically. Note that the thickness is shown greater than the width in the figures to clearly show the layer structure, and therefore the aspect ratio differs from the actual one.

[0044] Base Sheet: A transparent resin film is preferably used for the base sheet 11, which serves as the base material for the circuit sheet. Examples of such resin films include polyethylene terephthalate (PET) resin, polyethylene naphthalate (PEN) resin, polycarbonate (PC) resin, methacrylic (PMMA) resin, polypropylene (PP) resin, polyurethane (PU) resin, polyamide (PA) resin, polyethersulfone (PES) resin, polyetheretherketone (PEEK) resin, triacetyl cellulose (TAC) resin, and cycloolefin polymer (COP). A film made of a film-forming composition may also be used as the base sheet 11. Alternatively, the base sheet 11 may be provided with a primer layer, a surface protective layer, or an overcoat layer for antistatic purposes, which enhances adhesion to the conductive wires 12 or protective layer 13, or may be surface-treated by corona treatment, plasma treatment, ultraviolet irradiation, or the like. The primer layer preferably has high adhesion to the base sheet. Examples include a paint layer containing a resin such as a urethane-based, polyester-based, acrylic-based, vinyl acetate-based, vinyl chloride-based, styrene-acrylic, acrylic-silicone-based, or styrene-butadiene-based resin, or a paint layer containing an emulsion of such a resin.

[0045] Circuit Wiring: For ease of explanation, only one conductive wire 12 constituting the circuit wiring is shown in FIG. 1 , but typically, such conductive wires 12 are arranged in a pattern on the base sheet 11 to form a circuit (circuit wiring network). Examples of materials for the conductive wire 12 include conductive pastes and conductive inks containing powder of highly conductive metals such as copper, aluminum, silver, or alloys containing these metals. Among these metals or alloys, silver wiring, which primarily uses silver, is preferred because it has high conductivity and is less susceptible to oxidation than copper. The conductive wire 12 can also be wiring made of graphite powder or carbon powder such as carbon fiber or carbon black, or wiring made from a material that combines these with a metal.

[0046] In addition to printing, the circuit wiring may be formed by forming conductive portions on the base sheet 11 using metal vapor deposition, and then generating a circuit pattern by etching or the like. When metal vapor deposition is performed, metals such as copper, aluminum, nickel, chromium, zinc, and gold can be used. Among these, copper is preferred because of its low electrical resistance and low cost.

[0047] The circuit sheet 10 is manufactured by printing circuit wiring (conductive lines 12) at predetermined locations on a transparent resin film that serves as the base sheet 11. A film-forming composition is then applied thereon and cured to form the protective layer 13. In this manner, the circuit sheet 10 can be obtained. If the cycloolefin polymer or the physical property adjuster contains a reactive functional group, it can also be reacted with the base film.

[0048] <Sensor sheet> Another embodiment of a protective layer made of a film-forming composition is shown in the front view of Figure 2A and the plan view of Figure 2B. A sensor sheet 20 such as a capacitance sensor sheet shown in these figures is formed by applying a film-forming composition to a base sheet 21 so as to cover conductive wires 22 and sensor electrodes 24, forming a protective layer 13. For convenience, only one sensor electrode 24 is shown here, and the sensor sheet 20 having the sensor electrode 24 together with circuit wiring will be described as an example.

[0049] Sensor electrode: The base sheet 21 or conductive wire 22 that forms the base material of the sensor sheet 20 is the same as that used for the circuit sheet 10. The sensor electrode 24 can be formed from a conductive paste or conductive ink with circuit wiring formed thereon, a metal vapor deposition film, or the like, but can also be formed from a transparent conductive polymer. If a highly transparent material is used, it becomes possible to emit light at the sensor position by transmitting backlight illumination.

[0050] Examples of transparent conductive polymers include polythiophene, polypyrrole, polyaniline, polyparaphenylene, and polyacetylene. Specific examples include PEDOT / PSS (poly-3,4-ethylenedioxythiophene-polystyrene sulfonic acid). Transparent conductive polymers that are commercially available as paints or printing inks can be used. Alternatively, the sensor electrode 24 can be made using a conductive paste or ink containing a highly transparent material, such as metal nanoparticles such as silver nanoparticles, carbon nanoparticles, or indium tin oxide (ITO) powder.

[0051] The sensor sheet 20 is manufactured by printing circuit wiring (conductive wires 22) and sensor electrodes 24 at predetermined locations on a transparent resin film that serves as a base sheet 21. A film-forming composition is then applied thereon, and the solvent is volatilized and cured to form a protective layer 23. In this manner, the sensor sheet 20 can be obtained.

[0052] <Sensor Sheet (Part 2)> Another embodiment of the sensor sheet 30 is shown in the front view of Figure 3A and the plan view of Figure 3B. The sensor sheet 30 shown in these figures is the same as the sensor sheet 20 described above in that the circuit wiring (conductive wires 32) and sensor electrodes 34 on the base sheet 31 are covered with a protective layer 33 formed by applying a film-forming composition. However, the sensor sheet 30 of this embodiment differs in that it is formed into a three-dimensional shape. Note that the raw materials of each component are the same.

[0053] The sensor sheet 30 can be formed by forming circuit wiring (conductive wires 32) and sensor electrodes 34 on a flat base sheet 31, as in the case of the sensor sheet 20, and then thermally deforming the sheet. Alternatively, the circuit wiring (conductive wires 32) and sensor electrodes 34 can be formed on a three-dimensionally formed base sheet 31 by printing, vapor deposition, or the like. When the base sheet 31 is thermally deformed in a later process, it is preferable that the glass transition temperature Tg of the cycloolefin polymer contained in the film-forming composition that forms the protective layer 33 is close to the glass transition temperature Tg of the base sheet 31. This is because the closer the glass transition temperatures Tg are, the more similar the deformation levels of the base sheet 31 and the protective layer 33 become, making it less likely that distortion, deformation, cracking, or the like will occur.

[0054] <Sensor Sheet (Part 3)> The sensor sheet may be formed into a three-dimensional shape and then coated with a protective layer. The protective layer can be provided by applying a film-forming composition to the three-dimensional surface using a spray coating method or the like.

[0055] It will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novel features and effects of the present invention. Therefore, all such modifications are included within the scope of the present invention. For example, a term described at least once in the specification or drawings together with a different term having a broader or similar meaning may be replaced with that different term anywhere in the specification or drawings. Furthermore, the configurations of the embodiments are not limited to those described in the above embodiments, and various modifications are possible.

[0056] <Preparation of Samples 1 to 12> The present invention will be further described based on examples (comparative examples). Film-forming compositions were prepared by mixing the materials shown in the following tables, and designated Samples 1 to 12. A PET film was used as a substrate sheet, and a 0.5 μm-thick conductive film made of PEDOT / PSS (trade name: Orgacon EL-P3145, manufactured by AGFA) and a 10 μm-thick conductive wire made of silver paste (trade name: FA-323, manufactured by Fujikura Kasei Co., Ltd.) were formed in parallel on the surface of the substrate sheet. Then, a film-forming composition of any of Samples 1 to 12 was applied to a thickness of 8 μm to the surface of the substrate sheet on which the conductive film and conductive wires were formed, thereby preparing a test circuit sheet coated with the conductive film and conductive wire. However, both ends of the conductive film were left uncoated, leaving exposed portions of the conductive film (exposed portions) for resistance measurement. Each test circuit sheet obtained was assigned the same sample number as the film-forming composition applied.

[0057]

[0058]

[0059] In Table 1, as the type of base polymer, "COC" represents a cycloolefin copolymer (trade name: APL6509T, manufactured by Mitsui Chemicals, Inc., Tg 80 ° C.), "COP1" represents a cycloolefin polymer (trade name: ZEONOR 1020R, manufactured by Nippon Zeon Co., Ltd., Tg 102 ° C.) and is a COP resin that does not have a polar group in the cyclo ring, "COP2" represents a cycloolefin polymer (trade name: ARTON F4520, manufactured by JSR Corporation, Tg 164 ° C.) and is a COP resin that contains a polar group in the cyclo ring, "acrylic" represents an acrylic resin paint (trade name: Aron S-1017, manufactured by Toagosei Co., Ltd., Tg 95 ° C.), and "urethane" represents a polyurethane resin paint (trade name: TAKELAC WS-5100, manufactured by Mitsui Chemicals, Inc., Tg 120 ° C.). Comparing the polarity of COP2, COP1, acrylic, and urethane, acrylic and urethane have high polarity, which is designated as "high." COP2 is medium, designated as "medium," while COP1 and COC are low, designated as "low." Furthermore, because the amount of solvent added was adjusted at the end so that the total of each material and solvent for each sample was 100% by volume, the solvent's "concentration (volume %)" column is designated as "balance."

[0060] <Various Tests> The samples were subjected to the various tests described below.

[0061] [Printability 1] Viscosity: To evaluate printability from the viewpoint of viscosity, the viscosity of each sample was observed. The results are shown in the "Viscosity" column of Table 1. In Table 1, "A" indicates a viscosity within the range in which screen printing can be performed without any problems. "B" indicates a viscosity that is somewhat high and allows screen printing, but does not allow for an increase in printing speed, making it difficult for mass production. "C" indicates a viscosity that is too high to be printed.

[0062] [Printability 2] Bubbles: To evaluate printability based on the degree of bubble formation in the film, the presence or absence of bubbles in the film was observed for each sample. The results are shown in the "Bubbles" column in Table 1. In Table 1, "A" indicates that no bubbles were formed. "B" indicates that a small amount of bubbles were formed. "C" indicates that a large amount of bubbles were formed.

[0063] [Film Quality 1] Transmittance: To evaluate film quality based on film transparency, the film-forming composition of each sample was applied to a PET film to form a film with a thickness of 8 to 25 μm. The parallel light transmittance of this film was measured at wavelengths of 200 to 800 nm using a spectrophotometer (Shimadzu Corporation, "UV-1600PC").

[0064] [Film Quality 2] Adhesion: To evaluate the film quality from the viewpoint of adhesion to the substrate sheet, an adhesion test was conducted on each sample. More specifically, the test was conducted using the cross-cut method in accordance with JIS K5600-5-6 (ISO2409), and the test results were classified into six levels. The results are shown in the "Adhesion" column of Table 1. In Table 1, the numbers 0 to 5 indicate the classification of the test results using the cross-cut method, with 0 indicating no peeling and 5 indicating peeling of 35% or more. A score of 0 or 1 can be considered to indicate good adhesion. In Table 1, samples 3 and 6 were rated "2," samples 1, 4, and 5 were rated "1," sample 2 was rated "3," and the other samples were rated "0."

[0065] [Film Quality 3A] Moisture Resistance A: To evaluate the film quality from the viewpoint of moisture resistance, a moisture resistance test was conducted on each sample. More specifically, the test circuit sheet of each sample was placed in an atmosphere of 85% humidity and 85°C for 250 hours, 500 hours, 750 hours, and 1000 hours, and the moisture resistance was evaluated based on the change in resistance value of the conductive film made of transparent conductive polymer after each time period. This moisture resistance test based on the change in resistance value was designated "Moisture Resistance A." The resistance value was measured using a resistance meter (tester) from the exposed portions at both ends of the conductive film made of transparent conductive polymer. As a result, a very gradual increase in resistance was observed after 250 hours for Samples 4 and 5, Samples 7 and 8, and Samples 11 and 12, and the resistance after 1000 hours relative to the resistance before exposure to the humidity was 1.2 times for Sample 4, 1.1 times for Sample 5, 2.6 times for Sample 7, 2.2 times for Sample 8, 1.1 times for Sample 11, and 1.1 times for Sample 12, falling within the range of approximately 1.1 to 1.2 times for COP1 resin and 1.1 to 2.6 times for COP2 resin. On the other hand, the resistance was 20.0 times for Sample 9 and 10.5 times for Sample 10.

[0066] [Film Quality 3B] Moisture Resistance B: For each sample placed under the same conditions as the moisture resistance test described above, the color of the conductive film made of a transparent conductive polymer was observed and the moisture resistance was evaluated based on the change in color, in addition to the moisture resistance test A in which the resistance value was measured. This moisture resistance test based on the change in color is referred to as "Moisture Resistance B." The change in color of the conductive film was evaluated based on the color difference ΔE, an index defined as the distance between coordinates in the CIE 1976 L*a*b* color space, in accordance with JIS Z 8781-4. This color difference can be measured, for example, using a handheld spectrophotometer ("JX777" manufactured by Color Techno Systems Co., Ltd.) or a color difference meter ("CR-400" manufactured by Konica Minolta, Inc.). A color difference ΔE of 13 or less between the samples before and after the test is considered preferable, as it is difficult to distinguish the color difference with the naked eye, and a color difference ΔE of 6.5 or less is considered more preferable. In the moisture resistance B test, changes were observed in samples 4 and 5 after 500 hours, and after 1000 hours, the change was ΔE 3.97 in sample 4, ΔE 3.60 in sample 5, ΔE 3.00 in sample 7, and ΔE 3.00 in sample 8. On the other hand, ΔE was 15.00 in sample 9 and 7.72 in sample 10. Furthermore, ΔE was 4.00 in samples 11 and 12.

[0067] [Film Quality 4A] Weather Resistance A: To evaluate the film quality from the perspective of weather resistance, a heat cycle test was conducted on the test circuit sheets of each sample. More specifically, each test circuit sheet was placed in a thermo-hygrostat with a temperature setting range of -40°C to +85°C, a temperature increase rate of 3°C / min, and a temperature decrease rate of 2°C / min. Weather resistance was evaluated based on the change in resistance of the conductive film made of transparent conductive polymer after 1,000 hours. This weather resistance test, measured by the change in resistance, was designated "Weather Resistance A." As a result, the resistance values ​​after the heat cycle test were 0.9 times higher than the resistance values ​​before the test for Samples 4, 5, 7, and 8. However, the resistance values ​​were 1.5 times higher for Sample 9 and 2.0 times higher for Sample 10. Furthermore, the resistance values ​​were 1.4 times higher for Samples 11 and 12.

[0068] [Film Quality 4B] Weather Resistance B: For each sample placed under the same conditions as the heat cycle test, the color of the conductive film made of the transparent conductive polymer was observed, and weather resistance was evaluated based on the change in color, separate from the Weather Resistance A test in which resistance was measured. This weather resistance test based on color change is designated "Weather Resistance B." The resulting ΔE values ​​after the test were ΔE 1.02 for Sample 4, ΔE 0.65 for Sample 5, ΔE 1.10 for Sample 7, and ΔE 0.80 for Sample 8. On the other hand, ΔE 2.55 for Sample 9 and ΔE 3.00 for Sample 10. Furthermore, ΔE 2.00 was observed for Samples 11 and 12.

[0069] [Film Quality 5] Sulfuration Resistance: A sulfuration resistance test was conducted to evaluate the film quality from the perspective of sulfuration resistance. More specifically, each test circuit sheet was placed in an enclosed space containing sulfur powder and left in a saturated sulfur vapor atmosphere at 85°C for 250 hours. After 250 hours, the state of the conductive wires made of silver paste was observed visually and by resistance measurement. The results of the sulfuration resistance test showed that samples 1, 4, 5, 7, 8, and 10 maintained low resistance values ​​and did not break. Samples 11 and 12 also maintained low resistance values ​​and did not break. Sample 9 showed blackened areas across the entire width of the conductive wire, and the resistance value exceeded 2 MΩ, the maximum displayable value on the tester, and was therefore evaluated as having a break.

[0070] <Discussion> Based on the results of each of the above tests, the following discussion was made.

[0071] [Printability 1] Viscosity: All samples were rated "B" or higher, indicating that screen printing was possible with all samples based on viscosity. Looking more closely, a comparison of Samples 2 to 5 revealed that adding polyolefins such as liquid polybutene, or even functional fillers such as titanium oxide or zinc oxide, to COP1 resin improved printability in terms of viscosity. Therefore, it was found that not only polyolefins such as liquid polybutene, but also functional fillers such as titanium oxide or zinc oxide can act as viscosity adjusters, enabling the viscosity to be adjusted to a suitable level. Furthermore, it was found that COP resins have superior viscosity suitability compared to COC resins. Furthermore, Samples 11 and 12 contained high amounts of maleic anhydride-modified polypropylene (10% by volume and 20% by volume, respectively), yet still achieved a viscosity rating of "A," demonstrating that polyolefins such as maleic anhydride-modified polypropylene can be added at high concentrations without adversely affecting printability.

[0072] [Printability 2] Bubbles: Bubbles were observed in Samples 2 and 6, which did not contain functional fillers such as titanium oxide or zinc oxide, indicating that functional fillers act as foam inhibitors and improve printability. Furthermore, a comparison of Samples 2 and 3 revealed that the inclusion of polybutene improved viscosity and bubble formation, indicating that polybutene serves as a printability improver. Similarly, a comparison of Samples 6 and 11, or Samples 6 and 12, revealed that the inclusion of a polyolefin such as maleic anhydride-modified polypropylene improved bubble formation, indicating that such polyolefin serves as a foam inhibitor.

[0073] [Film Quality 1] Transmittance: The transmittance at 550 nm was 87% for the film of Sample 3, which did not contain filler, and 82% for the film of Sample 10, which was made only from urethane resin. Compared to the transmittance of 89.2% for PET film alone, it was found that COP resin had a higher transmittance than urethane resin. Furthermore, the transmittance waveform of the film of Sample 2, which was made only from COP resin without any property adjuster, was nearly identical to that of PET film, indicating that COP resin has a high visible light transmittance approaching that of PET resin. In a comparison between COC resin and COP resin, the value of Sample 1 was higher than that of Sample 4, indicating that COC resin had a higher transmittance than COP resin.

[0074] On the other hand, when comparing the transmittances of Samples 6 to 8, the transmittance in the visible light region of 550 nm was almost the same, but the transmittance of Samples 7 and 8 was lower than that of Sample 6 in the ultraviolet region of 350 nm. This result is thought to be because Samples 7 and 8 contain functional fillers, such as titanium oxide or zinc oxide, that are not contained in Sample 6, causing the functional fillers to reflect and block ultraviolet light. Furthermore, when comparing the transmittances of Samples 6, 11, and 12, Samples 11 and 12 showed a slight decrease in transmittance in the visible light region of 550 nm compared to Sample 6, and also a decrease in transmittance in the ultraviolet region of 350 nm. This result is thought to be because Samples 11 and 12 contain polyolefins, such as maleic anhydride-modified polypropylene, that are not contained in Sample 6, causing the polyolefins to reflect and block ultraviolet light. This polyolefin also functioned as an ultraviolet inhibitor. Furthermore, a comparison of Samples 2 and 3 revealed that polybutene also functioned as an ultraviolet inhibitor.

[0075] [Film quality 2] Adhesion: Comparing sample 2 and sample 6, sample 2, which used a COP1 resin with low polarity and no property-adjusting agent, had poor adhesion, whereas sample 6, which used a COP2 resin with medium polarity but no property-adjusting agent, had slightly improved adhesion. Therefore, it was found that from the viewpoint of adhesion, it is preferable to use a COP resin with medium polarity, i.e., a polar COP resin.

[0076] Furthermore, when comparing Sample 2 and Sample 3, which use COP resins of the same polarity, Sample 3, which contains polybutene, had improved adhesion compared to Sample 2, which did not, demonstrating that polyolefins such as polybutene function as adhesion improvers. Furthermore, Samples 4 and 5, which contain functional fillers, had better adhesion than Sample 3, which did not, demonstrating that functional fillers also function as adhesion improvers. A comparison of Samples 6 to 8 also revealed that the inclusion of functional fillers significantly improved adhesion. Furthermore, a comparison of Samples 6, 11, and 12 also showed that the sample containing maleic anhydride-modified polypropylene had improved adhesion, demonstrating that polyolefins other than polybutene also function as adhesion improvers.

[0077] [Film quality 3] Moisture resistance: Samples 9 and 10 showed a large increase in resistance and a large change in ΔE, whereas samples 4 and 5, 7 and 8, and 11 and 12 showed limited change in resistance and color, demonstrating that samples 4 and 5, 7 and 8, and 11 and 12 have excellent moisture resistance. These results demonstrate that polyolefins such as polybutene and maleic anhydride-modified polypropylene, or functional fillers, function as moisture resistance improvers and enhance film quality.

[0078] [Film Quality 4] Weather Resistance: In the Weather Resistance Test A, after 1000 hours of testing, the change in the resistance value of the conductive film for Samples 4, 5, 7, and 8 was 0.9 times, while that for Sample 9 was 1.5 times and that for Sample 10 was 2.0 times. Furthermore, in the Weather Resistance Test B, after 1000 hours of testing, the color change ΔE of the conductive film for Samples 4, 5, 7, and 8 was 0.65 to 1.10, while that for Sample 9 was 2.55 and that for Sample 10 was 3.00. These results indicate that Samples 4, 5, 7, and 8 have superior weather resistance compared to Sample 9 or Sample 10, and that polyolefins such as polybutene or functional fillers function as weather resistance improvers to enhance film quality. Furthermore, for Samples 11 and 12, the change in the resistance value of the conductive film in the Weather Resistance Test A was both 1.4 times, and the color change ΔE of the conductive film in the Weather Resistance Test B was both 2.00. These results show that the weather resistance is not as good as that of Sample 7 or Sample 8, but it is better than that of Sample 9 or Sample 10, and it was found that the maleic anhydride-modified polypropylene also functions as a weather resistance improver and enhances the quality of the coating.

[0079] [Film Quality 5] Sulfuration Resistance: The results of the sulfuration resistance test showed that sulfuration was not accelerated and sulfuration resistance was improved in Samples 4, 5, 7, 8, and Samples 11 and 12. Therefore, it was found that polyolefins such as polybutene and maleic anhydride-modified polypropylene, or functional fillers function as sulfuration resistance improvers and enhance film quality.

[0080] [Overall]: A comparison of Samples 2 and 3 shows that adding polybutene to COP resin improves printability and adhesion. Although adhesion is improved, there are some difficulties, and because of printability, it was found that even COP1 resin, which has low polarity, can form a film from the film-forming composition. Similarly, a comparison of Samples 6 and 11 shows that adding maleic anhydride-modified polypropylene to COP resin improves printability and adhesion. Therefore, it was found that even COP2 resin, which has low polarity, can form a film from the film-forming composition.

[0081] 10 Circuit sheet, 20 Sensor sheet, 30 Sensor sheet

Claims

1. A film-forming composition for use as a protective layer for a circuit sheet or a sensor sheet, comprising: Contains a cycloolefin polymer, a property adjusting agent, and a solvent Film-forming compositions.

2. The cycloolefin polymer is a ring-opening polymer of a cycloolefin or a copolymer of a cycloolefin and an olefin. The film-forming composition of claim 1.

3. The cycloolefin polymer has a polar group in a cyclo ring. The film-forming composition according to claim 1 or 2.

4. The physical property adjusting material is at least one of a printability improving material and a film quality improving material. The film-forming composition according to any one of claims 1 to 3.

5. The printability improving material functions at least as a stringing suppressing material that suppresses stringing, a wettability improving material that prevents repellency on the printing substrate and prevents the occurrence of printing unevenness and mottled patterns, and a cutting improving material that enables continuous printing. The film-forming composition of claim 4.

6. The film quality improving material functions as at least one of a gas barrier improving material that suppresses gas permeability, a heat resistance improving material that increases heat resistance, a light resistance improving material that prevents discoloration, and an ultraviolet light inhibitor that suppresses the transmission of ultraviolet light. The film-forming composition according to claim 4 or claim 5.

7. The physical property adjusting material is at least one of a polyolefin and a functional filler. The film-forming composition according to any one of claims 1 to 6.

8. The polyolefin is polybutene or maleic anhydride modified polypropylene. The film-forming composition of claim 7.

9. The physical property adjusting material is contained in an amount of 0.1 to 30% by volume. The film-forming composition according to any one of claims 1 to 8.

10. The physical property adjusting agent has a polar group selected from a hydroxyl group, an amino group, a carbonyl group, a carboxyl group, a nitro group, a sulfo group, an ester group, an amide group, and a halogen group. The film-forming composition according to any one of claims 1 to 9.

11. The physical property adjusting agent has a reactive functional group selected from an epoxy group, a methacryl group, a vinyl group, a mercapto group, and an amino group. The film-forming composition according to any one of claims 1 to 10.

12. The film-forming composition according to any one of claims 1 to 11. Membrane.

13. A substrate sheet, a circuit wiring, and a protective layer formed of a film made of the film-forming composition according to any one of claims 1 to 11. Circuit sheet.

14. It is a three-dimensional shape with curved surfaces. The circuit sheet according to claim 13.

15. A substrate sheet, a circuit wiring, a sensor electrode, and a protective layer formed of a film made of the film-forming composition according to any one of claims 1 to 11. Sensor sheet.

16. It is a three-dimensional shape with curved surfaces. The sensor sheet according to claim 15.