JP7694202B2 - Conductive composition for molded film, molded film and method for producing same, molded body and method for producing same - Google Patents

Description

The present invention relates to a conductive composition for molded films, a molded film and its manufacturing method, a molded body and its manufacturing method.

Patent Document 1 discloses a specific conductive circuit integrated molded product having a resin molded body, a base film embedded flush with one surface of the resin molded body, and a conductive circuit disposed between the resin molded body and the base film.
Patent Document 1 describes a method for manufacturing the conductive circuit integrated molded product, in which a base film 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 metal thin film.

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 specific 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 to realize a low resistance conductive pattern.

Patent Document 3 also 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 base film are thermocompression-bonded to each other, thereby giving the decorative layer an uneven shape that follows the pattern of the printed layer.

JP 2012-11691 A JP 2011-252140 A JP 2007-296848 A

According to the method of Patent Document 1, a conductor can be easily provided on the surface of a molded body. On the other hand, there is an increasing demand for forming a conductive circuit on the surface of a substrate of various shapes, such as a substrate having an uneven surface or a curved surface. When a conductive circuit is formed by laminating a film having a conductive layer on the surface of such a substrate, the film needs to be deformed to match the surface shape of the substrate. When the film is deformed, a large tensile force may be generated in parts of the conductive layer. This tensile force causes breakage of the conductive layer, resulting in a problem of reduced conductivity. Furthermore, when forming a conductive circuit on such a substrate having an uneven surface or a curved surface, it is necessary to integrate the film and the substrate after or at the same time as deforming the film having the conductive layer, but during this integration process, stress is applied to the conductive circuit due to friction with the plastic substrate at high temperatures. This stress at high temperatures also causes breakage of the conductive layer, resulting in a problem of reduced conductivity.

The present invention was made in consideration of these circumstances, and aims to provide a conductive composition for molded films capable of producing molded films in which the decrease in conductivity due to tensile force and high-temperature stress is suppressed, a molded film in which the decrease in conductivity due to tensile force and high-temperature stress is suppressed, and a molded body with excellent conductivity and a method for producing the same.

The conductive composition for molded films according to the present embodiment is
A conductive composition for producing a molded film for forming a conductive layer on a substrate surface having an uneven surface or a three-dimensional curved surface, comprising:
Contains a resin (A), conductive fine particles (B), and a solvent (C),
The solvent (C) includes a solvent (C1) represented by the following formulas (1) to (3).

In the formula, R ¹ represents a divalent alkylene group having 2 to 5 carbon atoms,
R ² to R ⁶ each represent a hydrogen atom or a methyl group.
Furthermore, R ⁷ to R ¹¹ each represent a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or a methoxy group, and at least one of R ⁷ to R ¹¹ is a methyl group, an ethyl group, an isopropyl group, or a methoxy group.

In one embodiment of the conductive composition for molded films, the conductive fine particles (B) include one or more types of conductive fine particles selected from silver powder, copper powder, silver-coated powder, copper alloy powder, conductive oxide powder, and carbon fine particles.

In one embodiment of the conductive composition for molded films, the resin (A) has a cyclic structure in the main chain.

In one embodiment of the conductive composition for molded films, the resin (A) has an aromatic ring structure and an ester bond in the main chain.

In one embodiment of the conductive composition for molded films, the content of the solvent (C1) is 40 parts by mass or more in total per 100 parts by mass of the solvent (C).

In one embodiment of the conductive composition for molded films, the solvent (C1) is a solvent represented by the formula (1), and R ¹ in the formula is one selected from the group consisting of 1,1-ethylene group, 1,2-ethylene group, 1,1-propylene group, 1,2-propylene group, 2,2-propylene group, and 1,3-propylene group,
Alternatively, it is a solvent represented by the formula (3) in which one or two of R ⁷ to R ¹¹ are a methyl group, an ethyl group or a methoxy group.

The molded film according to the present embodiment is a molded film having a conductive layer on a base film,
The conductive layer is a cured product of the conductive composition for molded films of the present embodiment.

One embodiment of the molded film of the present invention is a molded film having a decorative layer and a conductive layer on a base film,
The conductive layer is a cured product of the conductive composition for molded films of the present embodiment.

In one embodiment of the molded film of this embodiment, the base film is a film selected from polycarbonate, polymethyl methacrylate, polypropylene, and polyethylene terephthalate, or a laminate film of these.

The molded article according to the present embodiment is a molded article in which a conductive layer is laminated on a substrate,
The conductive layer is a cured product of the conductive composition for molded films of the present embodiment.

The first method for producing a molded body according to the present embodiment includes the steps of: printing the conductive composition for a molded film according to the present embodiment on a base film and drying the composition to produce a molded film;
placing the formed film on a substrate;
and b) integrating the molded film and the substrate by an overlay molding process.

The second method for producing a molded body according to the present embodiment includes the steps of: printing the conductive composition for a molded film according to the present embodiment on a base film and drying the composition to produce a molded film;
forming the formed film into a predetermined shape;
placing the formed film in an injection mold;
and forming a substrate by injection molding and integrating the formed film with the substrate.

A third method for producing a molded body according to the present embodiment includes the steps of: printing the conductive composition for a molded film according to the present embodiment on a base film and drying the composition to produce a molded film;
placing the formed film in an injection mold;
The method includes a step of molding a substrate by injection molding and transferring the conductive layer in the molded film to the substrate side.

The present invention provides a conductive composition for molded films capable of producing molded films in which the decrease in conductivity due to tensile force and high-temperature stress is suppressed, a molded film in which the decrease in conductivity due to tensile force and high-temperature stress is suppressed, and a molded body with excellent conductivity and a method for producing the same.

FIG. 2 is a schematic cross-sectional view showing an example of a molded film according to the present embodiment. FIG. 2 is a schematic cross-sectional view showing another example of the molded film of the present embodiment. 1A to 1C are schematic process diagrams showing an example of a first manufacturing method of a molded body. FIG. 4 is a schematic process diagram showing another example of the second manufacturing method of a molded body. 5A to 5C are schematic process diagrams showing another example of the third manufacturing method of a molded body.

The conductive composition for a molded film, the molded film, the molded article, and the method for producing the same according to the present embodiment will be described in detail below.
In the present embodiment, the term "cured product" refers not only to products that have been cured by chemical reaction, but also to products that have been cured without chemical reaction, such as products that have been hardened by evaporation of a solvent.

[Conductive composition for molded films]
Contains a resin (A), conductive fine particles (B), and a solvent (C),
The solvent (C) includes a solvent (C1) represented by the following formulas (1) to (3).

In the formula, R ¹ represents a divalent alkylene group having 2 to 5 carbon atoms,
R ² to R ⁶ each represent a hydrogen atom or a methyl group.
Furthermore, R ⁷ to R ¹¹ each represent a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or a methoxy group, and at least one of R ⁷ to R ¹¹ is a methyl group, an ethyl group, an isopropyl group, or a methoxy group.

The present inventors have investigated screen-printable conductive compositions in order to produce molded films that can be applied to uneven substrate surfaces and have process suitability for integration with plastic substrates. In order to apply the compositions to the production of molded films, various adjustments were made to the resin structure, conductive fine particles, and solvent. As a result, it was discovered that the frequency of cracks occurring when the obtained molded film is tensile-deformed at a high temperature at which it can be molded varies depending on the type of solvent contained in the conductive composition, particularly the use of a solvent having a specific aromatic alcohol structure, and that the frequency of printing defects such as chipping and peeling when printed at high speed and the magnitude of change in resistance value during tensile deformation at the high temperature, especially when the degree of deformation is large, vary depending on the glass transition point and main chain structure of the resin combined with the mixed solvent. Based on this knowledge, the inventors conducted an investigation and found that when a conductive composition that does not contain any solvent having a specific aromatic alcohol structure is printed on a resin film and then dried by heating, significant deterioration in the conductivity of the conductive layer pattern and cracks in the conductive layer occur when the molded film is deformed by pulling at a high temperature that corresponds to its softening point, and further, when the printing speed is increased when printing the conductive composition, the frequency of occurrence of printing defects such as chipping and scratching increases significantly. The same was true when a conductive layer was provided on a decorative layer.

Even if the molded film has a conductive layer that cracks or a large change in resistance value occurs when deformed by pulling at such high temperatures, there is no problem when it is used alone as a flat film circuit board or when it is used in a bent state on a two-dimensional curved surface. However, when it is used as a molded film that is integrated with the shape of a non-flat substrate surface, such as an uneven shape or a three-dimensional curved shape, the molded film will be deformed. Therefore, it is predicted that the conductive layer cannot follow the deformation of the resin film and peels off or breaks from the base film, resulting in a decrease in the conductivity of the conductive layer.
In addition, the uneven surface and three-dimensional curved surface in the present invention refer not only to a surface having a gently 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, such as a hemispherical, conical, cylindrical, or rectangular prism. In addition, when a certain three-dimensional 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 three-dimensional shape in which one or more partial hemispherical shapes are combined with a plane shape, it is a three-dimensional 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 flexible substrate or the like, and are shapes that can be realized, for example, by shaping a moldable film by three-dimensional molding under heating.

Based on these findings, the inventors conducted extensive research and discovered that when a solvent having a specific aromatic alcohol structure is contained, the change in resistance value that occurs when the molded film is pulled with a particularly large degree of deformation is small, and that when the printing speed is increased when printing the above-mentioned conductive composition and printing is performed in a state of increased productivity, the occurrence of printing defects such as chipping and scratching is highly suppressed, which led to the completion of the present invention.
That is, the conductive composition for molded films of the present invention can easily produce a molded film having a thick conductive layer with excellent conductivity by screen printing or the like by using a resin, conductive fine particles, and a solvent having a specific aromatic alcohol structure in combination. In addition, a molded film produced using the conductive composition for molded films can suppress a decrease in conductivity even when used on a non-flat substrate surface. Furthermore, by using the molded film, a molded product can be obtained in which a conductive circuit is formed on any surface, such as an uneven surface or a curved surface, on a substrate made of a three-dimensional plastic having practical strength.

The conductive composition for molded films in this embodiment contains at least a resin (A), conductive fine particles (B), and a solvent (C), and may further contain other components as necessary. Each component of such a conductive composition for molded films will be described below.

<Resin (A)>
The conductive composition of this embodiment contains a binder resin (A) to provide film-forming properties and adhesion to the base film or decorative layer. In addition, in this embodiment, the resin (A) is contained, so that the conductive layer can be given flexibility. Therefore, the conductive layer is prevented from breaking due to stretching by containing the resin (A).

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.

The main chain structure of the resin (A) preferably contains a cyclic structure, and it is particularly preferable that the main chain structure has both an aromatic ring structure and an ester bond, because the high affinity with the solvent (C), particularly (C1), described below leads to the spreading and entanglement of larger molecular chains of the resin (A) in the conductive composition, thereby improving the maintenance of conductivity during molding and tensioning and the defect suppression performance during printing.
In the present invention, the cyclic structure refers to an alicyclic structure, an aromatic ring structure, or a heterocyclic structure in which one ring is a 4- to 14-membered ring.
Examples of the alicyclic structure include monocyclic structures such as a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a cyclohexene ring, a cycloheptane ring, a cyclooctane ring, a cyclodecane ring, and a cyclotetradecane ring, and condensed ring structures such as a bornane ring, an isobornane ring, an adamantane ring, a decalin ring, and a steroid skeleton.
Examples of the aromatic ring structure include monocyclic structures such as a benzene ring, a furan ring, a 1,4-dioxine ring, a pyrrole ring, a pyridine ring, a pyrazine ring, a triazine ring, an imidazole ring, a pyrazole ring, an oxazole ring, a thiazole ring, a thiophene ring, a triazole ring, and a tetrazole ring, and condensed ring structures such as a naphthalene ring, a tetralin ring, an azulene ring, an anthracene ring, a perylene ring, an indane ring, an indole ring, a benzofuran ring, a benzimidazole ring, and a benzoxazole ring. As in the above examples, in the present invention, a structure in which an aromatic ring structure is condensed or directly bonded to an alicyclic structure, and a heterocyclic structure exhibiting aromaticity are all considered to be aromatic ring structures.
In the present invention, the heterocyclic structure refers to a heteroatom-containing (non-carbon atom) ring structure other than the above-mentioned aromatic ring structures, and examples thereof include a tetrahydrofuran ring, a pyran ring, a tetrahydropyran ring, a pyrrolidine ring, a piperidine ring, a piperazine ring, and an isocyanurate ring.
The linking site of the cyclic structure in the main chain structure of the resin (A) is not particularly limited, and it is sufficient that the cyclic structure is linked to the main chain via a total of two or more covalent bonds from any one or two atoms constituting the cyclic structure.

In this embodiment, it is also preferable that the resin (A) has two or more substituents selected from a hydroxyl group, an amino group, a carboxyl group, and an acid anhydride group in one molecule. In this case, the resin (A) can be three-dimensionally crosslinked by combining it with a crosslinking agent (D) described later, and can be suitably used in applications where hardness is required for the conductive layer.

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 described later.
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 represents the sum of the hydroxyl value and the acid value of the resin (A).

From the viewpoint of maintaining electrical conductivity during stretching during molding and resistance to frictional stress with the base plastic at high temperatures during the integration process with the plastic base material, the glass transition temperature (Tg) of resin (A) is preferably 0°C or higher and 130°C or lower, and more preferably 5°C or higher and 120°C or lower. From the same viewpoint, when resin (A) has multiple glass transition points, it is preferable that none of the glass transition points is below 0°C.

In this embodiment, the resin (A) may be synthesized by the methods described in the Examples below or other known methods, or a commercially available product having the desired physical properties may be used. In this embodiment, the resin (A) may be used alone or in combination of two or more types.

The content of resin (A) in the conductive composition of this embodiment may be adjusted appropriately according to the application, etc., and is not particularly limited, 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 amount of solids contained in the conductive composition. If the content of resin (A) is equal to or more than the above lower limit, the film-forming property and adhesion to the base film, etc. are improved, and flexibility can be imparted to the conductive layer. If the content of resin (A) is equal to or less than the above upper limit, the content of conductive fine particles (B) can be relatively increased, and a conductive layer with excellent conductivity can be formed.

<Conductive fine particles (B)>
The conductive fine particles (B) exhibit conductivity when multiple conductive fine particles come into contact with each other within the conductive layer, and in this embodiment, an appropriate selection is made from those that can obtain conductivity without being heated at high temperatures.
The conductive fine particles used in this embodiment include metal fine particles, carbon fine particles, conductive oxide fine particles, and the like.
Examples of metal fine particles include powders of simple metals 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 simple metal 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.

In this embodiment, it is preferable to include 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, and a conductive layer with excellent extensibility and conductivity retention performance when molded into a three-dimensional shape as a molded film described later can be formed.

The shape of the conductive fine particles (B) is not particularly limited, and spherical, flake-like, chain-aggregated, and other shapes can be used as appropriate. From the viewpoints of maintaining printability and maintaining conductivity during molding and stretching, flake-like or chain-aggregated shapes are particularly preferred.
In the present invention, "spherical" refers to particles in general that are spherical, egg-shaped, crushed spherical, pebble-shaped, or polyhedral and have a low aspect ratio, specifically, particles with an aspect ratio of about 1 or more and 2 or less. In addition, in the present invention, "flake-like" refers to two-dimensional flat shapes generally called scale-like, scale-like, plate-like, flat, sheet-like, etc., and among these, those with an aspect ratio of 3 or more and 500 or less are particularly preferred. Furthermore, in the present invention, "chain-aggregated" refers to amorphous shapes generally in which a plurality of the above-mentioned spherical conductive fine particles are directly fused and bonded together.

The D50 particle size of the conductive fine particles (B) is not particularly limited, but from the viewpoints of maintaining dispersibility and printability in the conductive composition, maintaining conductivity during molding, and resistance to injection molding processes using molten resin or high-temperature friction resistance of molded resin, 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 this embodiment, 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.) was used to add an appropriate amount of conductive fine particles (B) to an aqueous solution containing 0.5 volume% of the commercially available surfactant polyoxyethylene octylphenyl ether (Triton X-100 manufactured by Roche Diagnostics Co., Ltd.) as a dispersant, and the solution was irradiated with 40 W ultrasonic waves for 180 seconds while stirring, and then measured. The determined median diameter (D50) was used as the average particle size of the conductive fine particles (B).

In the present embodiment, the conductive fine particles (B) may be used alone or in combination of two or more kinds.
The content ratio of the conductive fine particles (B) in the conductive composition of this embodiment is not particularly limited and may be appropriately adjusted according to the application, etc., but is preferably 50% by mass or more and 90% by mass or less, and preferably 55% by mass or more and 85% by mass or less, based on the total amount of solids contained in the conductive composition. If the content ratio of the conductive fine particles (B) is equal to or more than the above lower limit, a conductive layer with excellent conductivity can be formed. In addition, if the content ratio of the conductive fine particles (B) is equal to or less than the above upper limit, the content ratio of the resin (A) can be increased, improving film-forming properties and adhesion to the base film, etc., and imparting flexibility to the conductive layer.

<Solvent (C)>
In this embodiment, the solvent (C) is contained in order to dissolve the resin (A) and impart fluidity to provide printability, and to adjust the spread and entanglement of the molecular chain in the composition of the resin (A). In addition, in this embodiment, the solvent (C) is contained, and the spread of the molecular chain is adjusted, and wettability is imparted to the base film during printing, thereby improving the patterning accuracy during printing.

The solvent (C) of the present invention contains a high-boiling point solvent (C1) having a specific structure described below. By containing the solvent (C1), not only is the solubility of the resin (A) excellent and the infiltration suppression into the base film excellent, but also the appropriate wettability to the base film during printing is imparted, improving the patterning accuracy, particularly during high-speed printing. In addition, the polymer chains of the resin (A) are widely spread in the solvent (C) and exhibit appropriate fluidity, and the polymer chains are well entangled with each other during the formation of the conductive layer, thereby obtaining the effect of suppressing local stress concentration on a microscale that may lead to the disconnection of the connection (conductive path) between conductive particles in the conductive layer.

The solvent (C1) of the present invention can be any solvent having the structure of the following formulas (1) to (3) without any particular restrictions.

In the formula, R ¹ represents a divalent alkylene group having 2 to 5 carbon atoms,
R ² to R ⁶ each represent a hydrogen atom or a methyl group.
Furthermore, R ⁷ to R ¹¹ each represent a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or a methoxy group, and at least one of R ⁷ to R ¹¹ is a methyl group, an ethyl group, an isopropyl group, or a methoxy group.

The solvent (C1) may be used alone or in combination of two or more. Even if the solvent (C1) is solid at room temperature, it can be used without any problems if it becomes liquid as a mixed solvent with a solvent (C1) of a different structure or with another solvent (C2) described later. Furthermore, it is particularly preferable that the solvent (C1) has a boiling point of 180°C or higher and 270°C or lower.

Specific examples of such solvents (C1) include those having the structures listed below.

Further, the solvent (C1) is more preferably
The solvent is represented by the formula (1), and R ¹ in the formula is one selected from the group consisting of a 1,1-ethylene group (ethylidene group), a 1,2-ethylene group, a 1,1-propylene group (propylidene group), a 1,2-propylene group (methylethylene group), a 2,2-propylene group (dimethylmethylene group), and a 1,3-propylene group (propanylene group),
Or a solvent represented by the formula (3) in which one or two of R ⁷ to R ¹¹ are a methyl group, an ethyl group, or a methoxy group is particularly preferred. The use of these is particularly preferred in that the wettability to the base film during printing is further well balanced, the polymer chains of the resin (A) spread more widely in the solvent (C) to exhibit appropriate fluidity, and the polymer chains are well entangled with each other during the formation of the conductive layer.
Specific examples of such particularly preferred solvents (C1) include 2-phenylethanol, 1-phenylethanol, 2-(2-methylphenyl)ethanol, 2-(3-methylphenyl)ethanol, 2-(4-methylphenyl)ethanol, 3-phenyl-1-propanol, 1-phenyl-1-propanol, 1-phenyl-2-propanol, 2-phenyl-1-propanol, 2-methylbenzyl alcohol, 3-methylbenzyl alcohol, 4-methylbenzyl alcohol, 2-methoxybenzyl alcohol, 3-methoxybenzyl alcohol, 4-methoxybenzyl alcohol, and 3,4-dimethylbenzyl alcohol.

The solvent (C) of the present invention may contain a solvent (C2) other than the solvent (C1). The solvent (C2) preferably has a boiling point of 180°C or higher and 270°C or lower, and examples thereof include, but are not limited to, 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, and glycol ethers such as diethylene glycol diethyl ether.

The content of solvent (C1) in 100 parts by mass of the solvent (C) of the present invention is preferably 40 parts by mass or more and 100 parts by mass or less, from the viewpoint of effectively exerting the above-mentioned high-speed printing suitability and conductive path breakage prevention properties.

<Optional ingredients>
The conductive composition of the present invention may further contain other components as necessary, such as the crosslinking agent (D) described later, 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.

<Crosslinking agent (D)>

In this embodiment, a crosslinking agent (D) may be additionally used to crosslink the resin (A). The crosslinking agent (D) may be appropriately selected from those having two or more reactive functional groups in one molecule capable of forming a crosslink with the reactive functional group of the resin (A). Examples of such reactive functional groups include an epoxy group, an isocyanate group, a blocked isocyanate group, an alkyloxyamino group, an aziridinyl group, an oxetanyl group, a carbodiimide group, and a β-hydroxyalkylamide group.
The crosslinking agent (D) is preferably used in an amount of 0.05 parts by mass or more and 30 parts by mass or less, and more preferably 0.3 parts by mass or more and 25 parts by mass or less, based on 100 parts by mass of the resin (A).

Furthermore, in this embodiment, it is particularly preferable to combine the resin (A) having two or more first reactive functional groups selected from hydroxyl groups or amino groups in one molecule and the crosslinking agent (D) with a blocked isocyanate.
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, isocyanurate, etc., 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, a conductive layer can be obtained which is particularly strong and has excellent adhesion to substrates at high temperatures due to the crosslinking point structure generated by crosslinking, and in which the decrease in conductivity due to tensile force is particularly suppressed.

<Method of producing conductive composition>
The method for producing the conductive composition of this embodiment may be any method for dissolving or dispersing the resin (A), the conductive fine particles (B), the wire-shaped fine particles (C), and other components used as necessary, and the conductive composition can be produced by mixing them by a known mixing means.

[Formed film]
The molded film of this embodiment is a molded film having a conductive layer on a base film,
The conductive layer is a cured product of the conductive composition for molded films.
According to the molded film of this embodiment, a molded article can be obtained in which a conductive circuit is formed on any substrate surface, such as an uneven surface or a curved surface.
According to the molded film of this embodiment, a molded article can be obtained in which a conductive circuit is formed on any substrate surface, such as an uneven surface or a curved surface.
The layer structure of the molded film of this embodiment will be described with reference to Figures 1 and 2. Figures 1 and 2 are schematic cross-sectional views showing an example of the molded film of this embodiment.
The molded film 10 shown in the example of Fig. 1 includes a conductive layer 2 on a base film 1. The conductive layer 2 may be formed on the entire surface of the base film 1, or may be formed in a desired pattern as in the example of Fig. 1.
The molded film 10 shown in the example of Fig. 2 has a decorative layer 3 on a base film 1, and a conductive layer 2 on the decorative layer 3. As shown in the example of Fig. 2, the molded film 10 may also have, on the conductive layer 2, an electronic component 4 and a pin 5 for connecting to an extraction circuit.
Although not shown, a resin layer for protecting the conductive layer or the electronic component 4 may be provided on the conductive layer 2 or the electronic component 4, and the resin layer may serve as an adhesive layer or bonding layer for improving adhesion to the substrate described below.
In addition, although not shown in the figure, when the molded film 10 of this embodiment has a decorative layer 3, in addition to the example of Figure 2, it may have a layer structure having a decorative layer 3 on one side of the base film 1 and a conductive layer 2 on the other side.
The molded film of the present embodiment comprises at least a base film and a conductive layer, and may have other layers as required. Each layer of such a molded film will be described below.

<Base film>
In this embodiment, the base film can be appropriately selected from those having flexibility and extensibility to such an extent that it can follow the shape of the substrate surface under the molding temperature conditions when the substrate is formed, and it is preferable to select the base film according to the use of the molded body and the manufacturing method of the molded body.
For example, when the overlay molding method or the film insert method described below is adopted as a method for producing a molded body, the base film remains in the molded body, so the base film can be selected taking into consideration its function as a protective layer for the conductive layer.
On the other hand, when an in-mold transfer method, which will be described later, is employed as a method for producing a molded article, it is preferable to select a base film having releasability.

The base film can be appropriately selected from the above viewpoints, and may be, for example, a film 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 surface of these base films is subjected to a modification treatment such as a corona treatment.

In addition, if necessary, an anchor coat layer may be provided on the base film and the conductive composition may be printed on the anchor coat layer for the purpose of improving the printability of the conductive composition. The anchor coat layer is not particularly limited as long as it has good adhesion to the base film and further to the conductive composition and follows the film during molding, and organic fillers such as resin beads and inorganic fillers such as metal oxides may also be added as necessary. The method of 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, in order to prevent the surface of the molded body from being scratched, a hard coat layer may be provided on the base film, and a conductive composition and, if necessary, a decorative layer may be printed on the opposite side. The hard coat layer is not particularly limited as long as it has good adhesion to the base film and surface hardness and follows the film 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 applying, drying, and curing using a conventionally known coating method.

In addition, if the molded film of this embodiment has a decorative layer, it is preferable to select a base film that has transparency.

The thickness of the base film is not particularly limited, but can be, for example, 10 μm or more and 500 μm or less, and preferably 20 μm or more and 450 μm or less.

<Conductive Layer>
In the molded film of this embodiment, 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 this embodiment, it is preferable to form it 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 it 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 line 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.

The conductive composition is printed by screen printing, and then heated to dry and cause a crosslinking reaction and harden.
In order to sufficiently volatilize the solvent and promote the 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.

The thickness of the conductive layer can be adjusted appropriately according to the required conductivity, etc., and is not particularly limited, but can be, for example, 0.5 μm or more and 20 μm or less, and preferably 1 μm or more and 15 μm or less.

<Decorative layer>
The molded film of the present embodiment may have a decorative layer from the viewpoint of the design of the resulting molded article.
The decorative layer may be a layer having a single color, or may have any pattern.
For example, the decorative layer can be formed by preparing a decorative ink containing a coloring material, a resin, and a solvent, and then applying the decorative ink to the base film by a known printing method.
The coloring material can be appropriately selected from known pigments and dyes, and the resin can be appropriately selected from the same resins as the resin (A) in the conductive composition of the present embodiment.
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.

[Molded body]
The molded article of this embodiment is a molded article having at least a conductive layer laminated on a substrate, the conductive layer being a cured product of the conductive composition for molded films according to any one of claims 1 to 5. The molded article of this embodiment is formed from a molded film using the conductive composition for molded films of this embodiment, and therefore is a molded article having a conductive circuit formed on any surface, such as an uneven surface or a curved surface.
Hereinafter, three embodiments of the method for producing the molded body of the present embodiment will be described. Note that the molded body of the present embodiment may be produced by using the conductive composition of the present embodiment, and the method is not limited to these embodiments.

<First manufacturing method>
A first method for producing a molded body according to the present embodiment includes the steps of: printing the conductive composition for a molded film according to the present embodiment on a base film and drying the composition to produce a molded film;
placing the formed film on a substrate;
and b) integrating the molded film and the substrate by an overlay molding process.
The following description will be given with reference to FIG. 3, but the method for producing the molded film is as described above, so the description will be omitted here.

3 is a schematic process diagram showing an example of a first manufacturing method of a molded body. Each of (A) to (C) of FIG. 3 illustrates a molded film 10 and a substrate 20 arranged in a chamber box of a TOM (Three Dimension Overlay Method) molding machine, and the chamber box is omitted in (B) and (C) of FIG. 3.
In the first manufacturing method, first, the substrate 20 is placed on the table of the lower chamber box 22. Next, the molded film 10 of the present embodiment is passed between the upper chamber box 21 and the lower chamber box 22 and placed on the substrate 20. At this time, the molded film 10 may be placed so that the conductive layer faces either the substrate 20 side or the opposite side to the substrate 20, and is selected depending on the final use of the molded body. Next, the upper and lower chamber boxes are placed in a vacuum state, and the molded film is heated. Next, the table is raised to raise the substrate 20 15. Next, only the inside of the upper chamber box 21 is opened to the atmosphere (FIG. 3(B)). At this time, the molded film is pressed 16 against the substrate side, and the molded film 10 and the substrate 20 are bonded together to be integrated (FIG. 3(C)). In this manner, a molded body 30 can be obtained.

In the first manufacturing method, the substrate 20 can be prepared in advance by any method. In the first manufacturing method, the material of the substrate 20 is not particularly limited, and the substrate 20 may be made of resin or metal.

Note that in this first manufacturing method, the frictional stress with the substrate plastic at high temperatures in the aforementioned integration process with the substrate is due to the frictional stress between the conductive circuit of the molded film and the substrate at high temperatures when the molded film in FIG. 3(C) is pressed 16 against the substrate side and the molded film 10 and substrate 20 are bonded together to be integrated. In other words, in this first manufacturing method, the conductive layer is simultaneously subjected to a load due to tensile stress during molding and frictional stress with the substrate plastic at high temperatures.

<Second manufacturing method>
A second method for producing a molded body according to the present embodiment includes the steps of: printing the conductive composition for a molded film according to the present embodiment on a base film and drying the composition to produce a molded film;
forming the formed film into a predetermined shape;
placing the formed film in an injection mold;
and forming a substrate by injection molding and integrating the formed film with the substrate. Hereinafter, the second manufacturing method will be described with reference to Fig. 4. The second manufacturing method is sometimes called a film insert method.

Figure 4 is a schematic process diagram showing an example of the second manufacturing method of a molded body. In the second manufacturing method, the molded film 10 is molded into a predetermined shape in advance by a mold 11 (Figure 4 (A)). After the molded film 10 is heated and softened, or while being softened, it is sucked into the mold by vacuum or pressed against the mold by compressed air, or both, and molded by the mold 11 (Figure 4 (B)). At this time, the molded film 10 may be molded so that the conductive layer faces either the substrate 20 side described later or the side opposite the substrate 20, and this is selected depending on the final use of the molded body. Next, the molded molded film 10 is placed in a mold 12 for injection molding (Figures 4 (C) to 4 (D)). Next, resin is injected 14 from an opening 13 to form the substrate 20, and the molded film 10 and the substrate 20 are integrated to obtain a molded body 30 (Figure 4 (E)).

In the second manufacturing method, the substrate 20 does not need to be prepared in advance, and the molding of the substrate and the integration with the molded film can be performed simultaneously. The material of the substrate 20 can be appropriately selected from known resins used for injection molding.

Note that in this second manufacturing method, the frictional stress with the base plastic at high temperatures in the aforementioned integration process with the substrate is due to the frictional stress that the conductive layer on the molded film receives when high-temperature molten resin is injected into the mold when resin is injected 14 from the opening 13 to form the substrate 20 and the molded film 10 and the substrate 20 are integrated in FIG. 4(E). In other words, in this second manufacturing method, the conductive layer is subjected to a load due to tensile stress during molding, and then in a separate process, it is subjected to frictional stress with the base plastic at high temperatures.

<Third manufacturing method>
A third method for producing a molded body according to the present embodiment includes a step of printing the conductive composition for molded film of the present embodiment on a base film by screen printing and drying the composition to produce a molded film;
placing the formed film in an injection mold;
The method includes a step of molding a substrate by injection molding and transferring the conductive layer in the molded film to the substrate side.
The following description will be given with reference to Fig. 5. The third manufacturing method is sometimes called an in-mold transfer method.

Figure 5 is a schematic process diagram showing an example of the third manufacturing method of a molded body. In the third manufacturing method, a molded film 10 having peelability is selected as a base film and used. The molded film 10 is placed in an injection molding die 12 so that the conductive layer faces the substrate 20 side described later (Figure 5 (A)). Next, resin is injected 14 from an opening 13 to form the substrate 20, and the molded film 10 and substrate 20 are in close contact with each other, at least the conductive layer is transferred to the substrate 20 side (Figure 5 (B)), and a molded body 30 is obtained (Figure 5 (C)). In addition, if the molded film 10 has a decorative layer, the decorative layer and the conductive layer are transferred.

In the third manufacturing method, since there is no need to cut the base film, a long base film can be arranged as shown in the example of Figure 5. The material of the substrate 20 can be appropriately selected from known resins used for injection molding.

In addition, in this third manufacturing method, the frictional stress with the base plastic at high temperatures in the integration process with the substrate described above is due to the frictional stress that the conductive layer on the molded film receives when high-temperature molten resin is injected into the mold when resin is injected 14 from the opening 13 to form the substrate 20 in FIG. 5(C) and the molded film 10 and substrate 20 are brought into close contact with each other. In other words, in this third manufacturing method, the conductive layer is simultaneously subjected to a load due to tensile stress during molding and frictional stress with the base plastic at high temperatures.

The molded article obtained in this way makes it possible to mount circuits, touch sensors, and various electronic components on the plastic housings of home appliances, automobile parts, robots, drones, etc. It is also extremely useful for making electronic devices lighter, thinner, shorter, and smaller, improving design freedom, and increasing the functionality of these devices.

The present invention will be described in more detail below with reference to 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.

In the examples, the "functional group value" is calculated based on the molecular weight per functional group of each raw material (this is 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) [mg KOH/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.

When titration with potassium hydroxide is used to quantify the functional groups such as carboxyl groups and hydroxyl groups, the functional group values (acid value and hydroxyl value) can be directly determined from an appropriate amount of potassium hydroxide used for neutralization using a known and commonly used measuring method specified in, for example, JIS K 0070, and can be treated in the same way as the values calculated by the above 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.

Calculation example: Calculation is performed for trifunctional isocyanate compound "X" having an isocyanate amount of 23% measured by the method specified in JIS K 6806 (a method in which an isocyanate group is reacted with n-dibutylamine and the remaining n-dibutylamine is titrated with an aqueous hydrochloric acid solution) as a compound having an isocyanate group. The functional group equivalent of trifunctional isocyanate compound "X" is derived as follows from the above isocyanate amount (%) and the molecular weight of the isocyanate group (NCO = 44 g/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 calculating the 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") [mg KOH/g]
= (56.1 x 1000) / 191.3 = 293.3

<Resins (A1) to (A3)>
The following resins were used as resins (A1) to (A3).
Resin (A1): Acrylic resin manufactured by Mitsubishi Chemical Corporation, Dianal BR-106, weight average molecular weight 60,000, glass transition point 50° C., having no cyclic structure or ester bond in the main chain.
Resin (A2): Cellulose ester resin manufactured by Eastman Chemical Company, CAB551-0.2, weight average molecular weight 70,000, glass transition point 100° C., having a hydroxy group (functional value 54 mgKOH/g), having a cyclic structure in the main chain and having no ester bond.
Resin (A3): Phenoxy resin manufactured by InChem, PKHC, weight average molecular weight 43,000, glass transition point 67°C, having a hydroxyl group (functional group value 198 mg KOH/g), having a cyclic structure (aromatic ring structure) in the main chain and having no ester bond.

<Synthesis Example 1: Synthesis of Resin (A4)>
A reactor equipped with a stirrer, a thermometer, a rectifying tube, a nitrogen gas inlet tube, and a pressure reducing device was charged with 20.0 parts of dimethyl isophthalate, 9.0 parts of dimethyl terephthalate, 12.0 parts of ethylene glycol, 18.0 parts of neopentyl glycol, and 0.03 parts of tetrabutyl titanate, and gradually heated to 180 ° C. while stirring under a nitrogen stream, and an ester exchange reaction was carried out at 180 ° C. for 3 hours, the acid value was measured, and when it became 15 or less, the pressure in the reactor was gradually reduced to 1 to 2 torr, and when it reached a predetermined viscosity, the reaction was stopped and the mixture was removed, transferred to a fluorine-treated pallet, and cooled to obtain a polyester resin (A4) having a weight average molecular weight of 40,000, a glass transition point of 59 ° C., a hydroxyl group (functional group value 5 mg KOH / g), and an aromatic ring structure and an ester bond in the main chain.

<Synthesis Example 2: Synthesis of Resin (A5)>
A reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube was charged with 127.0 parts of a polyester polyol obtained from isophthalic acid and 3-methyl-1,5-pentanediol ("Kuraray Polyol P-2030" manufactured by Kuraray Co., Ltd.), 19.0 parts of isophorone diisocyanate, and 36.5 parts of toluene, and reacted at 90°C for 3 hours under a nitrogen stream, and then 5.5 parts of isophorone diamine was added and reacted at 90°C for a further 2 hours, after which the reaction was stopped by cooling, and finally the mixture was taken out and transferred to a pallet with a fluorine-treated surface and dried in a hot air drying oven at 120°C for 5 hours and then vacuum dried for 24 hours to obtain a solid urethane resin (A5) having a weight average molecular weight of 35,000, a glass transition point of 5°C, an amino group (functional group value 4 mgKOH/g), and an aromatic ring structure and an ester bond in the main chain.

The following conductive particles, solvent, and crosslinking agent were used.
<Conductive fine particles (B1) to (B5)>
Conductive fine particles (B1): Flake-shaped silver powder, average particle size 5.2 μm, manufactured by Fukuda Metal Foil and Powder Co., Ltd.
- Conductive fine particles (B2): manufactured by Fukuda Metal Foil and Powder Co., Ltd., chain agglomerated silver powder, average particle size 1.7 μm
Conductive fine particles (B3): Mitsui Mining & Smelting Co., Ltd., silver-coated copper powder, silver coating amount 10%, average particle size 2.0 μm
Conductive fine particles (B4): Ishihara Sangyo Kaisha, Ltd., needle-shaped conductive Sb-doped tin oxide powder, average particle size 2.9 μm
Conductive fine particles (B5): Expanded graphite, manufactured by Ito Graphite Co., Ltd., average particle size 15 μm

<Solvents (C1-1) to (C1-10)>
The following was used as the solvent (C1): In the molecular structures in the formulas, R ² to R ¹¹ are hydrogen unless otherwise specified.
Solvent (C1-1): 2-phenylethanol, where R ¹ in formula (1) is a 1,2-ethylene group. Solvent (C1-2): 1-phenylethanol (DL form), where R ¹ in formula (1) is a 1,1-ethylene group. Solvent (C1-3): 2-(2-methylphenyl)ethanol, where R ¹ in formula (1) is a 1,2-ethylene group and R ² is a methyl group. Solvent (C1-4): 3-phenyl-1-propanol, where R ¹ in formula (1) is a 1,3-propylene group. Solvent (C1-5): 1-phenyl-1-propanol, where R ¹ in formula (1) is a 1,1-propylene group. Solvent (C1-6): 2-phenyl-2-propanol, where R ¹ in formula (1) is a 2,2-propylene group. Solvent (C1-7): 4-phenyl-2-butanol, where R ¹ in formula (1) is a 1,3-butylene group; Solvent (C1-8): 2-phenoxyethanol, where R ¹ in formula (2) is a 1,2-ethylene group; Solvent (C1-9): 2-phenoxy-1-propanol, where R ¹ in formula (2) is a 1,2-propylene group; Solvent (C1-10): 3-methylbenzyl alcohol, where R ⁸ in formula (3) is a methyl group; Solvent (C1-11): 4-methoxybenzyl alcohol, where R ⁹ in formula (3) is a methoxy group; Solvent (C1-12): 3,4-dimethylbenzyl alcohol, where R ⁸ and R ⁹ in formula (3) are methyl groups; Solvent (C1-13): 4-isopropylbenzyl alcohol, where R ⁹ in formula (3) is an isopropyl group.

<Other solvents (C2-1) to (C2-4)>
The following solvents were used as other solvents (C2) not corresponding to the solvent (C1).
Solvent (C2-1): Benzyl alcohol Solvent (C2-2): Dipropylene glycol monomethyl ether Solvent (C2-3): Diethylene glycol monobutyl ether acetate Solvent (C2-4): 2-methoxypropanol

<Crosslinking agent (D1)>
Crosslinking agent (D1):
Blocked isocyanate solution manufactured by Baxeneden Chemicals, Trixene BI7982, containing three blocked isocyanate groups per molecule (functionality 195 mg KOH/g), non-volatile content 70% (solvent (C2-4): 2-methoxypropanol)

<Production Example 1: Preparation of Decorative Ink (E1)>
200 parts of a resin solution consisting of 80 parts of resin (A1) and 120 parts of solvent (C2-3) (resin (A6) only) was prepared, and 20 parts of a phthalocyanine blue pigment (LIONOL BLUE FG7351 manufactured by Toyo Color Co., Ltd.) and 10 parts by mass of a titanium oxide pigment (TIPAQUE CR-93 manufactured by Ishihara Sangyo Kaisha, Ltd.) were stirred and mixed therein, and the mixture was kneaded with 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 the solvent (C2-3) were added and stirred and mixed uniformly to obtain a decorative ink (E1).

<Example 1: Preparation of conductive composition for molded film (F1)>
20.0 parts of resin (A1) was dissolved in 30.0 parts of solvent (C1-1), stirred and mixed with 80.0 parts of conductive fine particles (B1), kneaded with a three-roll mill (manufactured by Kodaira Seisakusho), and then stirred and mixed uniformly with a planetary mixer to obtain a conductive composition for molded films (F1).

<Examples 2 to 69: Preparation of conductive compositions for molded films (F2) to (F69)>
Conductive compositions for molded films (F2) to (F69) were obtained in the same manner as in Example 1 (conductive composition (F1)), except that the types and amounts of the resin, solvent, conductive fine particles, and crosslinking agent (when a crosslinking agent was used, the crosslinking agent was added immediately before uniform stirring and mixing with a planetary mixer) in Example 1 (conductive composition (F1)) were changed as shown in Tables 1 to 5.
The numerical values for each material in Tables 1 to 5 are all in parts by mass.

<Comparative Examples 1 to 6: Preparation of Conductive Compositions for Molded Films (F70) to (F75)>
Conductive compositions for molded films (F70) to (F75) were obtained in the same manner as in Example 1 (conductive composition (F1)), except that the types and amounts of the resin, solvent, conductive fine particles, and crosslinking agent in Example 1 (conductive composition (F1)) were changed as shown in Table 5.

<Examples 70 to 138 and Comparative Examples 7 to 12>
Conductive compositions for molded films (F1) to (F65) were each printed on a polycarbonate (PC) base film (Teijin, Panlite 2151, thickness 300 μm, 300 mm × 210 mm) using a screen printer (Minoscreen, Minomat SR5575 semi-automatic screen printer) at a printing speed of 100 mm. Then, the film was heated in a hot air drying oven at 120° C. for 30 minutes to obtain a molded film having a conductive layer having a square solid pattern with a width of 15 mm, a length of 30 mm, and a thickness of 10 μm, a linear pattern with a line width of 3 mm, a length of 60 mm, and a thickness of 10 μm, and a stripe pattern with a line width of 150 μm, a line spacing of 150 μm, and a length of 60 mm.

<Example 139>
The decorative ink (G1) was applied to a polycarbonate base film (Teijin Limited, Panlite 2151, thickness 300 μm, 300 mm × 210 mm) using a blade coater so that the dry film thickness was 2 μm, and the film was heated at 120° C. for 30 minutes to form a decorative layer.
Next, in Example 73, the above-mentioned film with decorative layer was used instead of the polycarbonate base film, and a conductive layer was formed on the decorative layer, and a molded film having a polycarbonate film, a decorative ink layer, and a conductor laminated in that order was obtained in the same manner as in Example 73.

<Example 140>
In Example 73, a polycarbonate resin/acrylic resin two-layer co-extrusion film (manufactured by Sumitomo Chemical Co., Ltd., Technoloy C001, thickness 125 μm, 300 mm × 210 mm) was used instead of the polycarbonate base film, and a conductive composition for molded films was printed on the polycarbonate resin side. A molded film was obtained in the same manner as in Example 73.

<Example 141>
A molded film was obtained in the same manner as in Example 73, except that an acrylic resin film (manufactured by Sumitomo Chemical Co., Ltd., Technoloy S001G, thickness 250 μm, 300 mm × 210 mm) was used instead of the polycarbonate base film, and the drying conditions in the hot air drying oven were 80 ° C. and 30 minutes.

<Example 142>
In the above-mentioned Example 73, a moldable PET resin film (manufactured by Morino Kako Co., Ltd., Emron PETG resin sheet, thickness 250 μm, 300 mm × 210 mm) was used instead of the polycarbonate base film, and the drying conditions in the hot air drying oven were 70 ° C. and 30 minutes. A molded film was obtained in the same manner as in the above-mentioned Example 73.

<Example 143>
In the above-mentioned Example 73, a polypropylene film (Idemitsu Unitech Co., Ltd., Pure Thermo AG-306, thickness 200 μm, 300 mm × 210 mm) was used instead of the polycarbonate film, and the drying conditions in the hot air drying oven were 80 ° C. and 30 minutes. A molded film was obtained in the same manner as in the above-mentioned Example 73.

[(1) Volume resistivity measurement]
The volume resistivity (Ω cm) of the 15 mm×30 mm square solid conductive layers formed on the molded films of Examples 70 to 143 and Comparative Examples 7 to 12 was measured using a resistivity meter (Mitsubishi Chemical Analytech Co., Ltd., Loresta GP MCP-T610 resistivity meter, compliant with JIS-K7194, 4-terminal 4-probe constant current application method) (4-terminal probes spaced 0.5 cm apart). The results are shown in Tables 1 to 5.

[(2) Peel Adhesion Evaluation]
The conductive layer formed on the molded film of Examples 70 to 143 and Comparative Examples 7 to 12 was cut into a square solid 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 10 x 10 grid-like cuts were made so as to penetrate the conductive layer. Cellophane tape manufactured by Nichiban Co., Ltd. was attached to the conductive layer, and after removing trapped air and ensuring good adhesion, the tape was peeled off vertically. The degree of peeling of the coating film was evaluated as follows according to the ASTM-D3519 standard. The results are shown in Tables 1 to 5.
(Evaluation Criteria for Peel Adhesion)
A: Rating 5B to 4B, excellent adhesion B: Rating 5B to 4B, but the coating film suffered cohesive failure and part of the coating film on the surface side was detached C: Rating 3B or lower, poor adhesion

(3) Evaluation of high-speed printing
The stripe patterns formed on the molded films of Examples 70 to 143 and Comparative Examples 7 to 12, each having a line width of 150 μm, a line spacing of 150 μm, and a length of 60 mm, were observed using a digital microscope (Keyence VHX-6000) and evaluated as follows. The results are shown in Tables 1 to 5.
(High-speed printability evaluation criteria)
A: No chipping or scratching of the pattern, excellent linearity. B: Some constriction is observed in the pattern, but chipping or scratching is absent or very slight.
C: There is noticeable chipping or fading of the pattern, and the fine printability is poor.

(4) Wiring Resistance Evaluation
The molded films of Examples 70 to 143 and Comparative Examples 7 to 12 were cut out to a length of 70 mm and a width of 10 mm so that the conductive layer of the 3 mm x 60 mm linear pattern formed thereon was in the center, and used as measurement coupons. On the surface of the measurement coupon opposite the conductive layer, two lines perpendicular to the conductive layer from the longitudinal end were added with oil-based marker at 4 cm intervals as markers. Following these markers, the resistance values of positions 4 cm apart were measured using a tester, and these were taken as wiring resistance (Ω). The results are shown in Tables 1 to 5.

[(5) Hot Stretching Evaluation 1]
The measurement coupons of Examples 70 to 140 and Comparative Examples 7 to 12 were stretched in the longitudinal direction in a heating oven at 160° C. at a pulling speed of 10 mm/min to an elongation rate of 125%. After removing from the oven and cooling, the presence or absence of disconnection was evaluated using an optical microscope. In addition, the wiring resistance (Ω) was measured at positions corresponding to 4 cm intervals based on the original mark in the same manner as in the measurement of the wiring resistance described above, and the wiring resistance after stretching/wiring resistance before stretching was defined as the resistance variation rate (times) during hot stretching, and each was evaluated according to the following criteria. The results are shown in Tables 1 to 4.
(Whether or not there is a break in the wire)
A: No breaks were observed.
B: 1 to 2 minor cracks were observed. C: Severe disconnection or peeling of the conductive coating was observed. (Resistance variation rate during hot stretching)
A: 5 times or more but less than 10 times B: 10 times or more but less than 100 times C: 100 times or more

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

[(6) Hot Stretching Evaluation 2]
The heat stretching evaluation was performed in the same manner as in the heat stretching evaluation 1, except that the elongation rate was changed to 150%, and the evaluation was performed according to the following criteria. The results are shown in Tables 1 to 4.
(Whether or not there is a break in the wire)
A: No breaks were observed.
B: 1 to 2 minor cracks were observed. C: Severe disconnection or peeling of the conductive coating was observed. (Resistance variation rate during hot stretching)
A: 10 times or more but less than 100 times B: 100 times or more but less than 1000 times C: 1000 times or more

[(7) Hot Stretching Evaluation 3]
The measurement coupons of Examples 141 to 143 were stretched in the longitudinal direction in a heating oven at 120° C. at a pulling speed of 10 mm/min to an elongation rate of 125%. After removing from the oven and cooling, the presence or absence of disconnection was evaluated using an optical microscope. In addition, the wiring resistance (Ω) was measured at positions corresponding to 4 mm intervals based on the original mark in the same manner as in the measurement of the wiring resistance described above, and the wiring resistance after stretching/wiring resistance before stretching was defined as the resistance variation rate (times) during hot stretching, and each was evaluated according to the following criteria. The results are shown in Table 4.
(Whether or not there is a break in the wire)
A: No breaks were observed.
B: 1 to 2 minor cracks were observed. C: Severe disconnection or peeling of the conductive coating was observed. (Resistance variation rate during hot stretching)
A: 5 times or more but less than 10 times B: 10 times or more but less than 100 times C: 100 times or more

[(8) Hot Stretching Evaluation 4]
The heat stretching evaluation was performed in the same manner as in the heat stretching evaluation 3, except that the elongation rate was changed to 150%, and the evaluation was performed according to the following criteria. The results are shown in Table 4.
(Whether or not there is a break in the wire)
A: No breaks were observed.
B: 1 to 2 minor cracks were observed. C: Severe disconnection or peeling of the conductive coating was observed. (Resistance variation rate during hot stretching)
A: 10 times or more but less than 100 times B: 100 times or more but less than 1000 times C: 1000 times or more

[(9) Process resistance evaluation 1 during production of molded body by overlay molding]
A rectangular ABS resin molded product having a height of 10 mm and a length and width of 30 mm x width of 30 mm was placed so as to face the conductor side surface so as to overlap the position of the 3 mm x 60 mm linear pattern of the molded film of Examples 70 to 140 and Comparative Examples 7 to 12, and overlay molding was performed at a set temperature of 160 ° C. using a TOM molding machine (manufactured by Fuse Vacuum Co., Ltd.) to obtain a molded product in which the molded film molded into a rectangular shape and the ABS resin molded product are integrated. The scraping and resistance variation rate of the linear pattern wiring of this molded product were confirmed. The resistance variation rate was evaluated by measuring the wiring resistance (Ω) at a position corresponding to a 6 cm interval based on the original mark, and the wiring resistance after stretching/wiring resistance before stretching was defined as the resistance variation rate (times) during hot stretching, and each was evaluated according to the following criteria. The results are shown in Tables 1 to 4.
(Presence or absence of disconnection and resistance fluctuation rate)
A: No scraping of the wiring was observed, and the resistance fluctuation rate was 10 times or more but less than 50 times. B: One or two chipped ends due to scraping of the wiring were observed, or the resistance fluctuation rate was 50 times or more but less than 500 times. C: One or more breaks due to scraping of the wiring were observed.

[(10) Process resistance evaluation 2 during production of molded body by overlay molding]
Except for using the 3 mm×60 mm linear patterns of the molded films of Examples 131 to 140 and carrying out overlay molding at 120° C., molded bodies were obtained in the same manner as in Evaluation 1 of process resistance during production of molded bodies by overlay molding, and the scraping of the linear pattern wiring during overlay molding and the resistance variation rate were evaluated. The results are shown in Table 4.

[(11) Process resistance evaluation 1 during production of molded body by film insert molding]
A block-shaped metal mold having a rectangular parallelepiped protrusion in the center, measuring 30 mm x 30 mm x 10 mm in height and width, with a step of 10 mm, was placed facing the opposite side of the conductor side so as to overlap the position of the 3 mm x 60 mm linear pattern of the molded films of Examples 70 to 140 and Comparative Examples 7 to 12 above, and overlay molding was performed at a set temperature of 160°C using a TOM molding machine (manufactured by Fuse Vacuum Co., Ltd.) to obtain a moldable film molded into a rectangular parallelepiped shape and having a patterned conductor on the inside.
Next, the molded film molded into the rectangular parallelepiped shape was set in an injection molding machine (IS170 (i5), manufactured by Toshiba Machine Co., Ltd.) equipped with a valve gate type in-mold molding test mold, and a PC/ABS resin (LUPOYPC/ABSHI5002, manufactured by LG Chemical Co., Ltd.) was injection molded to obtain a molded body integrated with the molded film with a patterned conductor (injection conditions: screw diameter 40 mm, cylinder temperature 260 ° C., mold temperature (fixed side, movable side) 60 ° C., injection pressure 160 MPa (80%), holding pressure 100 MPa, injection speed 60 mm/sec (28%), injection time 4 seconds, cooling time 20 seconds). Washout due to injection of molten resin of the linear pattern of this molded body (deformation or disconnection of the wiring pattern due to the temperature and injection pressure of the molten thermoplastic resin) and resistance variation rate were confirmed. The resistance variation rate was evaluated by measuring the wiring resistance (Ω) at positions corresponding to 6 cm intervals based on the original mark, and the wiring resistance after stretching/wiring resistance before stretching was defined as the resistance variation rate (times) during thermal stretching. The results are shown in Tables 1 to 4.
(Disconnection and resistance fluctuation rate)
A: No washout of the wiring was observed at all, and the resistance fluctuation rate was 10 times or more but less than 50 times. B: Wiring distortion due to mild washout was observed, or the resistance fluctuation rate was 50 times or more but less than 500 times. C: One or more breaks due to washout of the wiring were observed.

[(12) Process resistance evaluation 2 during production of molded body by film insert molding]
Except for using the 3 mm x 60 mm linear patterns of the molded films of Examples 141 to 143 and performing overlay molding at 120 ° C., molded bodies were obtained in the same manner as in the process resistance evaluation 1 during the manufacture of molded bodies by overlay molding, and the degree of washout and resistance variation rate due to molten resin injection of the linear pattern during film insert molding were evaluated. The results are shown in Table 4.

[Summary of results]
It was found that the conductive layers formed using the conductive compositions of Comparative Examples 1 to 6, which do not contain the solvent (C1) as a solvent component, break or have an increased resistance when stretched at high temperatures during the three-dimensional molding process of the molded film, especially when the stretching elongation is large. In addition, a tendency was observed for chipping or fading of the pattern to occur when printing at a high printing speed.

On the other hand, from the results of Examples 70 to 143, the conductive composition of this embodiment did not break even when the stretching elongation was large when stretched at high temperatures during the three-dimensional molding process of the molded film, and the increase in resistance value was also well suppressed. This is presumably because the solvent component of the conductive composition of this embodiment contains a solvent (C1) having a specific aromatic alcohol structure, so that the polymer chains of the resin (A) component are widely spread in the solvent (C) and the polymer chains are well entangled when the conductive layer is formed, thereby exhibiting excellent cohesive force and conductivity retention properties at high temperatures of the conductive layer that can withstand stretching at high temperatures and large elongations during molding, and also achieving printability at high printing speeds without impairing both. At the same time, the inclusion of the solvent (C1) is believed to have been effective in suppressing the infiltration of the solvent near the interface between the base film and the conductive layer, which is important as the scaffolding for the conductive layer, and in suppressing breakage during stretching at high temperatures and large elongations during molding, and in suppressing printing defects (presumably due to suppression of the increase in viscosity of the conductive composition due to solvent absorption at the moment of contact with the substrate during printing). The balance of properties between stretching at high temperatures and large elongations during molding and printability at high printing speeds was particularly excellent in that resistance value increases and defects during printing are unlikely to occur when used in combination with a resin having a cyclic structure in the main chain, particularly a resin having an aromatic ring structure and an ester bond as the cyclic structure. This is believed to be due to the fact that the polymer chains are less likely to slip through the entanglement of the polymer chains of the resin (A) when softened at the molding temperature, making it less likely to form voids that become notches for breakage. Although the mechanism by which these properties are expressed remains unclear, it is speculated that the higher polar affinity resulting from the structural similarity between resin (A) and solvent (C1) allows the polymer chains of the resin (A) component to spread more widely in solvent (C) and exhibit moderate fluidity, and that the polymer chains become well entangled when the conductive layer is formed, resulting in the expression of toughness capable of suppressing localized stress concentrations on a microscale that could lead to the severing of connections (conductive paths) between conductive particles within the conductive layer.

In addition, due to the above-mentioned characteristics, a molded film having a conductive layer of the conductive composition of the present invention can produce an excellent wiring-integrated molded product even when the substrate surface has an uneven three-dimensional shape, particularly a complex three-dimensional shape with steep steps.

In this way, the molded films and wiring-integrated molded bodies using the conductive composition of this embodiment can be directly applied to plastic housings and three-dimensional parts for home appliances, automobile parts, robots, drones, etc., making it possible to fabricate lightweight, space-saving circuits, touch sensors, antennas, heating elements (heaters), electromagnetic shields, inductors (coils), resistors, and mount various electronic components without compromising design freedom. They are also extremely useful for making electronic devices lighter, thinner, shorter, and smaller, improving design freedom, and increasing functionality.

Reference Signs List 1 Base film 2 Conductive layer 3 Decorative layer 4 Electronic component 5 Pin 10 Molded film 11 Mold 12 Injection mold 13 Opening 14 Injection 15 Rising 16 Pressurizing 17 Resin 20 Substrate 21 Upper chamber box 22 Lower chamber box 30 Molded body

Claims (10)

A conductive composition for producing a molded film for forming a conductive layer on a substrate surface having an uneven surface or a three-dimensional curved surface, comprising:
Contains a resin (A), conductive fine particles (B), and a solvent (C),
The solvent (C) contains a solvent (C1) represented by the following formulas (1) to (3),
The resin (A) contains a resin having an aromatic ring structure and an ester bond in its main chain,
The conductive composition for a molded film , wherein the solvent (C1) satisfies the following condition (A) and/or (B) :

[In the formula, R ¹ represents a divalent alkylene group having 2 to 5 carbon atoms,
R ² to R ⁶ each independently represent a hydrogen atom or a methyl group.
R ⁷ to R ¹¹ each independently represent a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, or a methoxy group, and at least one of R ⁷ to R ¹¹ is a methyl group, an ethyl group, or a methoxy group.]

Condition (A): The solvent (C1) contains a solvent represented by the formula (1), and R ¹ in the formula (1) is one selected from the group consisting of a 1,1-ethylene group, a 1,2-ethylene group, a 1,1-propylene group, a 1,2-propylene group, a 2,2-propylene group, and a 1,3-propylene group.

Condition (B): The solvent (C1) contains a solvent represented by the formula (3), and one or two of R ⁷ to R ¹¹ in the formula (3) are a methyl group, an ethyl group, or a methoxy group.
The conductive composition for molded films according to claim 1, wherein the conductive fine particles (B) include one or more 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. 3. The conductive composition for formed films according to claim 1 , wherein the content of said solvent (C1) is 40 parts by mass or more in total per 100 parts by mass of said solvent (C). A molded film having a conductive layer on a base film,
A molded film, wherein the conductive layer is made of a cured product of the conductive composition for molded films according to any one of claims 1 to 3 . A molded film having a decorative layer and a conductive layer on a base film,
A molded film, wherein the conductive layer is made of a cured product of the conductive composition for molded films according to any one of claims 1 to 3 . The molded film according to claim 4 or 5, wherein the base film is a film selected from polycarbonate, polymethyl methacrylate, polypropylene, and polyethylene terephthalate, or a laminate film thereof. A molded article having a conductive layer laminated on a substrate,
A molded article, wherein the conductive layer is a cured product of the conductive composition for molded films according to any one of claims 1 to 3 . A step of producing a molded film by printing the conductive composition for molded films according to any one of claims 1 to 3 on a base film and drying it;
placing the formed film on a substrate;
and a step of integrating the molded film and the substrate by an overlay molding method. A step of producing a molded film by printing the conductive composition for molded films according to any one of claims 1 to 3 on a base film and drying it;
forming the formed film into a predetermined shape;
placing the formed film in an injection mold;
A method for producing a molded article, comprising the steps of: molding a substrate by injection molding; and integrating the molded film with the substrate. A step of producing a molded film by printing the conductive composition for molded films according to any one of claims 1 to 3 on a base film and drying it;
placing the formed film in an injection mold;
A method for producing a molded article, comprising the steps of: molding a substrate by injection molding; and transferring a conductive layer in the molded film to the substrate.