Resin wiring substrate and stretchable device

Abstract

The present invention has: a first resin layer (11) that contains a resin component composed of a first resin; a second resin layer (31) that is laminated on the first resin layer (11), contains a resin component composed of a second resin, and has a lower Young's modulus than the first resin layer (11); a wiring pattern (24) that is disposed between the first resin layer (11) and the second resin layer (31) and has a first surface (24a) formed in contact with the first resin layer (11) and a second surface (24b) formed in contact with the second resin layer (31), the second surface (24b) being on the side opposite from the first surface (24a); and a resin diffusion layer (23) that is disposed between the first resin layer (11) and the second resin layer (31), at least in a region that does not overlap the wiring pattern (24) in plan view, and contains a resin component composed of a third resin. The first resin, the second resin, and the third resin have a shared structural unit in which some or all of the structural units derived from a monomer are the same.

Description

Resin wiring substrate and stretchable device

[0001] The present invention relates to a resin wiring substrate and a stretchable device. This application claims priority to Japanese Patent Application No. 2023-187229, filed on October 31, 2023, the contents of which are incorporated herein by reference.

[0002] Wearable devices have attracted attention in a wide range of fields, including sports science and healthcare. It is desirable for wearable devices to be comfortable to wear. Therefore, it is desirable for them to be stretchable so that they can be worn on the object they are attached to. In this specification, devices with such characteristics are referred to as stretchable devices, regardless of their intended use.

[0003] Patent Document 1 describes a stretchable wiring board having a substrate containing an elastomer and wiring that is placed on one surface of the substrate and contains an elastomer and a conductive filler.

[0004] Patent Document 2 describes a bendable wiring board having a film made of polyurethane that can be synthesized by reacting a long-chain polyol with a polyisocyanate, and that has a temperature at which a storage modulus of 1 MPa is reached by dynamic viscoelasticity measurement of 155°C or higher, a storage modulus of 20 to 200 MPa at 25°C, a tensile strength of 20 to 80 MPa, and a breaking elongation of 500 to 900%, and circuit wiring formed in contact with the surface of the film.

[0005] JP 2020-53619 A International Publication No. 2020 / 090634

[0006] Resin wiring substrates used in stretchable devices are usually manufactured by a method of forming a wiring pattern on a resin substrate by a printing method. The resin wiring substrate is preferably one with a low Young's modulus and low strength so that a stretchable device with a comfortable fit can be formed. Therefore, when manufacturing a resin wiring substrate, it is preferable to use a resin substrate with a low Young's modulus on which the wiring pattern is formed.

[0007] However, when a wiring pattern is formed by a printing method on a resin substrate having a low Young's modulus, the mask used for printing is difficult to separate from the resin substrate, which tends to cause problems with mask separation. For this reason, it has been difficult to manufacture a resin wiring board having a wiring pattern formed by a printing method and having a low Young's modulus.

[0008] The present invention has been made in view of the above-mentioned problems, and aims to provide a resin wiring board that has low strength and can be manufactured using a method of forming a wiring pattern on a resin base material by a printing method, and a stretchable device including the same.

[0009] In order to solve the above problems, the present invention provides the following means: A resin wiring board according to one aspect of the present invention includes a first resin layer containing a resin component made of a first resin, a second resin layer laminated on the first resin layer, containing a resin component made of a second resin, and having a lower Young's modulus than the first resin layer, a wiring pattern disposed between the first resin layer and the second resin layer, the wiring pattern having a first surface formed in contact with the first resin layer and a second surface opposite to the first surface formed in contact with the second resin layer, and a resin diffusion layer disposed between the first resin layer and the second resin layer at least in a region not overlapping with the wiring pattern in a planar view, the resin diffusion layer containing a resin component made of a third resin, the first resin, the second resin, and the third resin having common structural units in which some or all of structural units derived from monomers are the same.

[0010] The resin wiring board of the present invention includes a first resin layer containing a resin component made of a first resin, a second resin layer containing a resin component made of a second resin and having a lower Young's modulus than the first resin layer, and a resin diffusion layer disposed between the first and second resin layers and at least in a region that does not overlap with the wiring pattern in a planar view, the resin diffusion layer containing a resin component made of a third resin, the first resin, the second resin, and the third resin having common structural units in which some or all of the structural units derived from the monomers are the same. Since the resin wiring board of the present invention includes the second resin layer having a lower Young's modulus than the first resin layer, the strength of the resin wiring board is lower than that of the first resin layer. Furthermore, since the structural units derived from the monomers of the first resin, second resin, and third resin are the same in some or all, the resin diffusion layer containing the third resin adheres the first resin layer containing the first resin to the second resin layer containing the second resin, making the first resin layer and the second resin layer less susceptible to delamination.

[0011] Therefore, in the resin wiring board of the present invention, for example, even if the first resin layer has a high Young's modulus that is less likely to cause plate-release defects, the second resin layer has a lower Young's modulus than the first resin layer and is adhered to the first resin layer by a resin diffusion layer, resulting in a resin wiring board with lower strength than the first resin layer. Therefore, in the resin wiring board of the present invention, a first resin layer with a high Young's modulus that is less likely to cause plate-release defects can be used, and the resin wiring board can be easily manufactured with high yield using a method of forming a wiring pattern on the first resin layer by a printing method. Moreover, because the resin wiring board of the present invention has a lower Young's modulus than the first resin layer, it can be preferably used as a material for a stretchable device that has a comfortable fit, even if the first resin layer has a high Young's modulus that is less likely to cause plate-release defects.

[0012] Furthermore, the stretchable device of the present invention includes the resin wiring board of the present invention, and therefore the stretchable device of the present invention has a comfortable fit.

[0013] 1 is a schematic diagram illustrating an example of a stretchable device of the present invention comprising a resin wiring board of the present invention. FIG. 2(a) is a cross-sectional view of the stretchable device shown in FIG. 1 cut along line A-A' shown in FIG. 1. FIG. 2(b) is a cross-sectional view of the stretchable device shown in FIG. 1 cut along line B-B' shown in FIG. 1. FIGS. 3(a) to 3(c) are process diagrams illustrating an example of a method for manufacturing the stretchable device shown in FIG. 1. FIG. 4 is an image of the cross-section of the laminate of Test Example 21 taken using a camera provided in an infrared spectroscopic analyzer. FIG. 5 is an infrared absorption (IR) spectrum obtained by performing mapping measurements of the laminate of Test Example 21 at 1 μm intervals in the thickness direction of the laminate by photothermal infrared spectroscopy (O-PTIR).

[0014] In order to solve the above problems and to provide a resin wiring board that has good flexibility and can be manufactured using a method for forming a wiring pattern by a printing method, the inventors focused on the Young's modulus of a resin substrate and a resin coating layer in a resin wiring board having a wiring pattern disposed between the resin substrate and the resin coating layer, and conducted extensive research as described below.

[0015] The inventors considered that a resin substrate having a high Young's modulus that is less likely to cause plate separation problems even when a wiring pattern is formed by a printing method could be used, and after forming the wiring pattern on the resin substrate, a low-strength resin coating layer having a lower Young's modulus than the resin substrate could be formed on the resin substrate so as to cover the wiring pattern, thereby producing a resin wiring board having a lower strength than the resin substrate.

[0016] However, when a resin coating layer with a low Young's modulus is formed on a resin substrate with a high Young's modulus, sufficient adhesion between the resin substrate and the resin coating layer is sometimes not obtained. If the adhesion between the resin substrate and the resin coating layer is insufficient, the resin substrate and the resin coating layer are likely to delaminate, making it difficult to obtain a resin wiring board with good flexibility. Therefore, the present inventors have focused on the composition of the resins forming the resin substrate and the resin coating layer and conducted extensive research in order to improve the adhesion between the resin substrate and the resin coating layer.

[0017] As a result, it was found that a resin coating layer can be formed by the following method: A monomer containing one or more compounds identical to the compound contained in the monomer used as the material for the resin forming the resin substrate is used, and this is polymerized to obtain a resin component. The obtained resin component is dispersed or dissolved to prepare a resin composition. The resin coating layer can be formed by applying this to the resin substrate and drying it.

[0018] More specifically, when the compound contained in the monomer used as the material for the resin forming the resin substrate and the compound contained in the monomer used as the material for the resin coating layer formed on the resin substrate are the same as one or more compounds, when a resin composition in which the resin components forming the resin coating layer are dispersed or dissolved is applied to the resin substrate, a portion of the resin components forming the surface of the resin substrate dissolves in the solvent contained in the resin composition and mixes with the resin composition. At this time, since the resin components in the resin composition are specific and similar to the resin components forming the resin substrate, the resin components forming the surface of the resin substrate quickly dissolve in the solvent contained in the resin composition.

[0019] As a result, a resin diffusion layer is formed between the resin coating layer obtained by drying the resin composition and the resin substrate, in which some or all of the structural units derived from the monomer are contained in the resin components of the resin substrate and the resin coating layer. Therefore, the resin component contained in the resin diffusion layer has common structural units, in which some or all of the structural units derived from the monomer are the same as those of the resin component contained in the resin substrate and the resin component contained in the resin coating layer. Because the resin component composition of this resin diffusion layer is similar to that of the resin substrate and the resin coating layer, it fully functions to improve the adhesion between the resin substrate and the resin coating layer. Therefore, it is estimated that interlayer delamination between the resin substrate and the resin coating layer can be effectively suppressed.

[0020] The inventors also formed a resin substrate with a high Young's modulus using various monomers. Then, they prepared a resin composition by dispersing or dissolving a resin component obtained by polymerizing a monomer containing a compound partially or entirely identical to the compound contained in the monomer used as the material for the resin substrate. Using the resulting resin composition, they formed a resin coating layer with a lower Young's modulus and lower strength than the resin substrate. As a result, they confirmed that a resin wiring board could be obtained that was lower in strength than the resin substrate, inhibited interlayer delamination between the resin substrate and the resin coating layer, and could be manufactured using a method for forming a wiring pattern on the resin substrate by a printing method. The present invention includes the following aspects.

[0021] [1] A resin wiring board comprising: a first resin layer containing a resin component made of a first resin; a second resin layer laminated on the first resin layer, containing a resin component made of a second resin, and having a lower Young's modulus than the first resin layer; a wiring pattern disposed between the first resin layer and the second resin layer, with a first surface formed in contact with the first resin layer and a second surface opposite to the first surface formed in contact with the second resin layer; and a resin diffusion layer disposed between the first resin layer and the second resin layer at least in a region not overlapping with the wiring pattern in a planar view, the resin diffusion layer containing a resin component made of a third resin, wherein the first resin, the second resin, and the third resin have common structural units in which some or all of the structural units derived from monomers are the same.

[0022] [2] The first resin, the second resin, and the third resin have different proportions of the common structural units contained in the structural units derived from the monomers, and the proportion of the common structural units in the third resin is a value between the proportion of the common structural units in the first resin and the proportion of the common structural units in the second resin, and changes continuously or stepwise in the thickness direction of the resin diffusion layer. The resin wiring board according to [1].

[0023] [3] The resin wiring board according to [1], wherein the common structural unit includes one or both of a structural unit derived from a compound having a urethane bond and a polymerizable unsaturated bond and a structural unit derived from a compound having a fluorene skeleton. [4] The resin wiring board according to [1], wherein the wiring pattern is made of a conductive resin containing the common structural unit.

[0024] [5] The resin wiring board according to [1], wherein the first resin contains a structural unit derived from a compound having a siloxane bond and a polymerizable unsaturated bond. [6] The resin wiring board according to [1], wherein the Young's modulus of the first resin layer is 3.5 times or more that of the second resin layer. [7] The Young's modulus of the second resin layer is 25 N / mm ２ The resin wiring board according to [1], which is the following: [8] The resin wiring board according to [1], wherein the first resin layer contains a filler. [9] A stretchable device comprising the resin wiring board according to any one of [1] to [8].

[0025] The resin wiring board and stretchable device of this embodiment will be described in detail below with reference to the drawings as appropriate. The drawings used in the following description may show characteristic portions enlarged for the sake of clarity. Therefore, the dimensional ratios of each component may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited to them. Appropriate modifications can be made within the scope of the present invention.

[0026] [Stretchable device] Fig. 1 is a plan view schematic diagram for explaining an example of a stretchable device of the present invention comprising a resin wiring board of the present invention. Fig. 2(a) is a cross-sectional view of the stretchable device shown in Fig. 1 cut along line A-A' shown in Fig. 1. Fig. 2(b) is a cross-sectional view of the stretchable device shown in Fig. 1 cut along line B-B' shown in Fig. 1.

[0027] The stretchable device of this embodiment shown in Figures 1, 2(a), and 2(b) includes a resin wiring board 1. The resin wiring board 1 has a resin base material 11 (corresponding to the "first resin layer" in the claims), a resin coating layer 31 (corresponding to the "second resin layer" in the claims), a wiring pattern 24, and a resin diffusion layer 23. The resin wiring board 1 and the resin base material 11 of this embodiment have a strip-like shape. As shown in Figures 1 and 2(b), two electronic components 41 are arranged on a first surface 11a of the resin base material 11 arranged approximately at the center in the longitudinal direction of the resin wiring board 1.

[0028] (Resin substrate 11) The resin substrate 11 is a sheet-like resin substrate, and is preferably stretchable. The resin substrate 11 contains a resin component made of a first resin and a filler that is contained as needed. The resin substrate 11 preferably contains a filler. This is because the resin substrate 11 has a sufficiently high Young's modulus, and is less likely to suffer from plate-release problems even when a wiring pattern 24 is formed on the resin substrate 11 by a printing method.

[0029] The Young's modulus of the resin substrate 11 is higher than that of the resin coating layer 31, and is preferably 3.5 times or more, and more preferably 5.0 times or more, the Young's modulus of the resin coating layer 31. This is because, when the Young's modulus of the resin substrate 11 is 3.5 times or more the Young's modulus of the resin coating layer 31, forming the resin coating layer 31 on the resin substrate 11 has a more pronounced effect of making the resin wiring board 1 weaker in strength than the resin substrate 11. Furthermore, when the Young's modulus of the resin substrate 11 is 3.5 times or more the Young's modulus of the resin coating layer 31, the effect of suppressing interlayer delamination of the resin wiring board 1 due to the formation of the resin diffusion layer 23 becomes more pronounced.

[0030] "First Resin" Examples of the first resin contained in the resin substrate 11 include epoxy-based resins, urethane-based resins, urea-based resins, polyurethane-urea-based resins, (meth)acrylic acid-based resins, polyacrylic resins, silicone-based resins, diene-based resins, polyester-based resins, polyether-based resins, polyamide-based resins, and polystyrene-based resins.

[0031] In this specification, the term "(meth)acrylic acid" encompasses both "acrylic acid" and "methacrylic acid." Furthermore, the term "(meth)acrylate" encompasses both "acrylate" and "methacrylate." The same applies to terms similar to (meth)acrylate; for example, the term "(meth)acryloyl group" encompasses both "acryloyl group" and "methacryloyl group."

[0032] The first resin preferably has, as a structural unit derived from a monomer, one or more structural units selected from a structural unit derived from a compound having a urethane bond and a polymerizable unsaturated bond (hereinafter, sometimes referred to as a "urethane-derived structural unit"), a structural unit derived from a compound having a fluorene skeleton (hereinafter, sometimes referred to as a "fluorene-derived structural unit"), a structural unit derived from a compound having a siloxane bond and a polymerizable unsaturated bond (hereinafter, sometimes referred to as a "siloxane-derived structural unit"), a structural unit derived from a (meth)acrylic acid alkyl ester (hereinafter, sometimes referred to as a "(meth)acrylic acid-derived structural unit"), and a structural unit derived from a reversible addition-fragmentation chain transfer agent (reversible addition fragmentation chain transfer polymerization, sometimes abbreviated herein as a "RAFT agent") (hereinafter, sometimes referred to as a "RAFT agent-derived structural unit").

[0033] The first resin preferably contains, as structural units derived from a monomer, one or both of a urethane-derived structural unit and a fluorene-derived structural unit, one or both of a siloxane-derived structural unit and a (meth)acrylic acid-derived structural unit, and a RAFT agent-derived structural unit. This is because it is easy to obtain a resin substrate 11 that has appropriate flexibility, a sufficiently high Young's modulus, and is less likely to experience plate-release problems even when a wiring pattern 24 is formed on the resin substrate 11 by a printing method. The first resin preferably contains, as structural units derived from a monomer, a siloxane-derived structural unit. This is because the resin substrate 11 and the resin coating layer 31 become a resin wiring board 1 that is even more resistant to delamination.

[0034] Among the structural units derived from the monomers contained in the first resin, the proportions of the urethane-derived structural units, fluorene-derived structural units, siloxane-derived structural units, (meth)acrylic acid-derived structural units, and RAFT agent-derived structural units are not particularly limited, and can be determined appropriately depending on the application of the resin substrate 11 and the properties such as the required strength and elongation at break.

[0035] The greater the number of urethane bonds in the resin substrate 11, the more likely it is that a resin wiring board 1 with excellent flexibility will be obtained. When the first resin contains urethane-derived structural units as structural units derived from monomers, the proportion of the urethane-derived structural units among the structural units derived from the monomers contained in the first resin is preferably 1% by mass to 80% by mass, and more preferably 5% by mass to 50% by mass. This is because when the proportion of the urethane-derived structural units is 1% by mass or more, the effect of including the urethane-derived structural units can be sufficiently obtained. Furthermore, when the proportion of the urethane-derived structural units is 80% by mass or less, structural units other than the urethane-derived structural units can be sufficiently included, making it easier to obtain a resin substrate 11 with a sufficiently high Young's modulus.

[0036] The greater the number of fluorene-derived structural units in the resin substrate 11, the more likely it is that the resin substrate 11 will have excellent flexibility and good durability. When the first resin contains fluorene-derived structural units as structural units derived from monomers, the proportion of fluorene-derived structural units among the structural units derived from monomers contained in the first resin is preferably 30% by mass to 99% by mass, and more preferably 35% by mass to 90% by mass. This is because when the proportion of fluorene-derived structural units is 30% by mass or more, the effect of containing fluorene-derived structural units can be sufficiently obtained. Furthermore, when the proportion of fluorene-derived structural units is 99% by mass or less, structural units other than fluorene-derived structural units can be sufficiently contained, making it easier to obtain a resin substrate 11 with a sufficiently high Young's modulus.

[0037] When the first resin has a siloxane-derived structural unit, the resin substrate 11 has moderate water repellency. As a result, the resin substrate 11 has excellent durability and is inhibited from deterioration over time due to moisture. Furthermore, when the first resin has a siloxane-derived structural unit, the resin substrate 11 has good tackiness (adhesiveness), and the resin substrate 1 and the resin coating layer 31 are even less susceptible to delamination.

[0038] When the first resin contains a siloxane-derived structural unit as a structural unit derived from a monomer, the proportion of the siloxane-derived structural unit is preferably 0.5 to 10 parts by mass relative to 100 parts by mass of a first oligomer obtained by polymerizing one or more monomers selected from a urethane-derived structural unit, a fluorene-derived structural unit, and a (meth)acrylic acid-derived structural unit by a known method. When the proportion of the siloxane-derived structural unit is 0.5 parts by mass or more, the effect of including the siloxane-derived structural unit is sufficiently obtained. Furthermore, when the proportion of the siloxane-derived structural unit is 10 parts by mass or less, structural units other than the siloxane-derived structural unit can be sufficiently included, making it easier to obtain a resin substrate 11 with properties suited to the application.

[0039] When the first resin has urethane-derived structural units as well as siloxane-derived structural units, the urethane bonds in the resin substrate 11 are less susceptible to hydrolysis, which is preferable because it results in a resin substrate 11 that is less susceptible to deterioration over time due to hydrolysis. When the first resin has urethane-derived structural units as well as siloxane-derived structural units, the greater the number of siloxane bonds in the resin substrate 11, the less susceptible the urethane bonds in the resin substrate 11 are to hydrolysis, resulting in a resin wiring board 1 with excellent durability. When the first resin has urethane-derived structural units as well as siloxane-derived structural units, the ratio of the number of urethane bonds to the number of siloxane bonds contained in the first resin is not particularly limited and can be determined appropriately depending on the application of the resin wiring board 1 and the properties such as the required durability and elongation at break.

[0040] When the first resin has (meth)acrylic acid-derived structural units, the greater the number of (meth)acrylic acid-derived structural units, the higher the Young's modulus, resulting in a resin substrate 11 that is less susceptible to plate release defects even when a wiring pattern 24 is formed on the resin substrate 11 by a printing method. When the first resin contains (meth)acrylic acid-derived structural units as structural units derived from monomers, the proportion of (meth)acrylic acid-derived structural units among the structural units derived from monomers contained in the first resin is preferably 21% to 40% by mass. This is because a proportion of (meth)acrylic acid-derived structural units of 21% by mass or more can sufficiently suppress plate release defects due to the inclusion of (meth)acrylic acid-derived structural units. Furthermore, when the proportion of (meth)acrylic acid-derived structural units is 40% by mass or less, structural units other than (meth)acrylic acid-derived structural units can be sufficiently contained, making it easier to obtain a resin substrate 11 with appropriate flexibility.

[0041] When the first resin has a RAFT agent-derived structural unit, variations in the degree of polymerization and crosslinking state are suppressed, resulting in a first resin that is easily dispersed or dissolved in a solvent. When the first resin contains a RAFT agent-derived structural unit as a structural unit derived from a monomer, it is preferably contained in an amount of 0.2 to 5 parts by mass relative to 100 parts by mass of the total monomers contained in the first resin. This is because when the RAFT agent-derived structural unit is contained in an amount of 0.2 parts by mass or more relative to 100 parts by mass of the total monomers contained in the first resin, the effect of containing the RAFT agent-derived structural unit is fully obtained. Furthermore, when the RAFT agent-derived structural unit is contained in an amount of 5 parts by mass or less relative to 100 parts by mass of the total monomers contained in the first resin, structural units other than the RAFT agent-derived structural unit can be sufficiently contained, making it easier to obtain a resin substrate 11 with properties suited to the application.

[0042] The first resin can be produced, for example, by the method described below. First, a first oligomer is produced by polymerizing one or more monomers selected from a compound having a urethane bond and a polymerizable unsaturated bond, a compound having a fluorene skeleton, and a (meth)acrylic acid alkyl ester by a known method. A second oligomer is then produced by polymerizing a compound having a siloxane bond and a polymerizable unsaturated bond by a known method. The first resin can then be produced by reversible addition-fragmentation chain transfer polymerization (RAFT polymerization) under known conditions using the first oligomer, the second oligomer, a polymerization initiator, and a RAFT agent. This production method is preferred because it facilitates the production of a first resin having a skeleton composed of a polymer of the first oligomer and short-chain branches containing structural units derived from a compound having a siloxane bond and a polymerizable unsaturated bond.

[0043] The first resin may be produced by a method of reversible addition-fragmentation chain transfer polymerization (RAFT polymerization) under known conditions using a compound having a urethane bond and a polymerizable unsaturated bond, a compound having a fluorene skeleton, a (meth)acrylic acid alkyl ester, a compound having a siloxane bond and a polymerizable unsaturated bond, a polymerization initiator, and a RAFT agent.

[0044] Examples of compounds having a urethane bond and a polymerizable unsaturated bond that are used as monomers when producing the first resin include known compounds (urethane(meth)acrylates) that have a urethane bond and a (meth)acryloyl group as the group having the polymerizable unsaturated bond. Only one type of compound having a urethane bond and a polymerizable unsaturated bond may be used, or two or more types may be used.

[0045] The compound having a urethane bond and a polymerizable unsaturated bond used in producing the first oligomer may be an oligomer having a urethane bond and a polymerizable unsaturated bond. Specific examples of oligomers having a urethane bond and a polymerizable unsaturated bond include acrylic urethanes, polyether urethanes, carbonate urethanes, polyester urethanes, and aromatic urethanes. As the oligomer having a urethane bond and a polymerizable unsaturated bond, it is preferable to use an acrylic urethane because it has good reactivity and results in a resin substrate 11 with excellent flexibility. It is more preferable to use an oligomer having a structural unit having a urethane bond and a (meth)acryloyl group, and a structural unit having a urethane bond but no (meth)acryloyl group. It is particularly preferable to use a compound represented by the following formula (1):

[0046]

[0047] As the oligomer having a urethane bond and a polymerizable unsaturated bond, it is also preferable to use an acrylic urethane represented by the following formula (12), since this gives a resin substrate 11 with good flexibility.

[0048] (n in formula (12) １ indicates the degree of polymerization, which is 1 to 40. １１ is a methylene chain having 1 to 40 carbon atoms which may be substituted with an alkyl group having 1 to 4 carbon atoms. １２ is a divalent group derived from a polyol.

[0049] In formula (12), n １ represents the degree of polymerization, which is 1 to 40, preferably 10 to 20. In formula (12), R １１ is a methylene chain having 1 to 40 carbon atoms, which may be substituted with an alkyl group having 1 to 4 carbon atoms. １１ is preferably a methylene chain having 1 to 8 carbon atoms which may be substituted with an alkyl group having 1 to 3 carbon atoms. １１ Specific examples of the group include -(CH ２ ) ２ -, -(CH ２ )３ -, -(CH ２ ) ４ -, -CH ２ CH (CH ２ CH ３ )-(CH ２ ) ４ -, -(CH ２ ) ４０ -, etc. A plurality of R included in formula (12) １１ may all be different, or some or all may be the same, and it is preferable that they are all the same for ease of production. １２ Examples of the divalent group derived from a polyol represented by the formula: ２ ) ２ -, -(CH ２ ) ３ -, -(CH ２ ) ４ -, -CH ２ CH (CH ３ ) CH ２ -, -CH ２ CH (CH ２ CH ３ )-(CH ２ ) ４ -, -CH ２ CH (CH ２ ) ８０ CH ３ - and so on. １２ is R １１ It may be the same as or different from.

[0050] The oligomer having a urethane bond and a polymerizable unsaturated bond is an oligomer having acryloyl groups (CH ) at both ends of an acrylic urethane represented by formula (12). ２ =CH ２ C(=O)-), one or both of which are methacryloyl groups (CH ２ =CH(CH ２ )C(═O)—) is also preferably used.

[0051] When an acrylic urethane is used as the oligomer having a urethane bond and a polymerizable unsaturated bond, it is preferable to use one having a weight-average molecular weight (Mw) of 30,000 to 85,000, and more preferably 30,000 to 70,000. Furthermore, when an acrylic urethane is used as the oligomer having a urethane bond and a polymerizable unsaturated bond, it is preferable to use one having a number-average molecular weight (Mn) of 20,000 to 45,000, and more preferably 20,000 to 40,000, because it can be easily produced. When the weight-average molecular weight (Mw) of the oligomer having a urethane bond and a polymerizable unsaturated bond is 30,000 or more and / or the number-average molecular weight (Mn) is 20,000 or more, it is easier to obtain a resin substrate 11 having better flexibility and durability. Furthermore, if the weight average molecular weight (Mw) is 85,000 or less and / or the number average molecular weight (Mn) is 45,000 or less, gelation of the resin components during polymerization for producing the first resin can be prevented.

[0052] As the oligomer having a urethane bond and a polymerizable unsaturated bond, for example, a polyether-based urethane represented by the following formula (13) and / or a polyester-based urethane represented by the following formula (14) may be used.

[0053] (n in formula (13) ２ represents the degree of polymerization, which is 1 to 50. m represents the degree of polymerization, which is 5 to 20. R １３ R is a divalent organic group having 1 to 10 carbon atoms and a polymerizable unsaturated bond. １４ and R １５ are monovalent terminal groups, and may be the same or different from each other. １６ and R １７ are monovalent terminal groups and may be the same or different from one another. １８ is a divalent organic group having 1 to 10 carbon atoms and a polymerizable unsaturated bond. １９ are divalent organic groups having 1 to 10 carbon atoms and each having a polymerizable unsaturated bond, and may be the same or different.

[0054] In formula (13), n ２ represents the degree of polymerization, which is from 1 to 50, and preferably from 10 to 40. In formula (13), m represents the degree of polymerization, which is from 5 to 20, and preferably from 10 to 20.

[0055] In formula (13), R １３ R is a divalent organic group having 1 to 10 carbon atoms and a polymerizable unsaturated bond. １３ Preferably, the group having a polymerizable unsaturated bond has a group containing an ethylenically unsaturated bond, and the group having a polymerizable unsaturated bond is an acryloyl group (CH ２ =CH ２ C(=O)-) and / or methacryloyl group (CH ２ =CH(CH ２ )C(=O)-) is preferably a divalent organic group having 1 to 10 carbon atoms. １３ represents a structure derived from an epoxy group, one or more methylene groups (-CH ２ It is preferable that the alkylene group contains any structure or group selected from a methylene chain having a carbonyl group (>C=O) and a carbonate group (-O-(C=O)-O-).

[0056] In formula (13), R １４ and R １５ are monovalent terminal groups and may be the same or different from one another. １４ and R １５ R is preferably a terminal group selected from the group consisting of a hydrogen atom, a hydroxyl group, a carboxyl group, an aldehyde group, and an amide group. １４ is preferably —OH or —COOH. １５ is R １３ R １５ If the structure connecting to is not a methylene group, -CH ２ OH or -CH ２ It is preferably COOH.

[0057] In formula (14), R １６ and R １７are monovalent terminal groups and may be the same or different from one another. １６ and R １７ R is preferably a terminal group selected from the group consisting of a hydrogen atom, a hydroxyl group, a carboxyl group, an aldehyde group, and an amide group. １６ and R １７ are -OH, -COOH, and -CH ２ OH, -CH ２ COOH, -C(=O)CH ３ It is preferable that it is any one selected from the following.

[0058] In formula (14), R １８ R is a divalent organic group having 1 to 10 carbon atoms and a polymerizable unsaturated bond. １８ Preferably, the group having a polymerizable unsaturated bond has a group containing an ethylenically unsaturated bond, and the group having a polymerizable unsaturated bond is an acryloyl group (CH ２ =CH ２ C(=O)-) and / or methacryloyl group (CH ２ =CH(CH ２ )C(=O)-) is preferably a divalent organic group having 1 to 10 carbon atoms. １８ represents a structure derived from an epoxy group, one or more methylene groups (-CH ２ It is preferable that the alkylene group contains any structure or group selected from a methylene chain having a carbonyl group (>C=O) and a carbonate group (-O-(C=O)-O-).

[0059] The oligomer having a urethane bond and a polymerizable unsaturated bond may be any of a random copolymer, a block copolymer, and an alternating copolymer, and is preferably a random copolymer because it can be easily produced.

[0060] The compound having a fluorene skeleton (9,9-bisphenylfluorene skeleton) used as a monomer when producing the first resin may be a fluorene compound having a fluorene skeleton and a reactive group such as a hydroxyl group or an amino group. Specific examples of the compound having a fluorene skeleton include bisphenolfluorene (BPF), biscresolfluorene (BCF), bisaminophenylfluorene (BAFL), and bisphenoxyethanolfluorene (BPEF). Only one type of compound having a fluorene skeleton may be used, or two or more types may be used.

[0061] Examples of (meth)acrylic acid alkyl esters used as monomers in producing the first resin include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, and decyl (meth)acrylate. Only one type of (meth)acrylic acid alkyl ester may be used, or two or more types may be used. The (meth)acrylic acid alkyl ester is preferably methyl (meth)acrylate because it has good dispersibility with the compound having a urethane bond and a polymerizable unsaturated bond, which is used as a monomer when producing the first resin.

[0062] Examples of the compound having a siloxane bond and a polymerizable unsaturated bond used as a monomer when producing the first resin include various known silicone resins having a (meth)acryloyl group as the group having a polymerizable unsaturated bond. Only one type of compound having a siloxane bond and a polymerizable unsaturated bond may be used, or two or more types may be used.

[0063] Examples of second oligomers obtained by polymerizing a compound having a siloxane bond and a polymerizable unsaturated bond include those having a structural unit derived from a modified polydialkylsiloxane in which a (meth)acryloyl group is bonded to one or both ends of a polydialkylsiloxane such as polydimethylsiloxane. The second oligomer is preferably one having a structural unit derived from a modified polydialkylsiloxane in which a (meth)acryloyl group is bonded to one end of the polydialkylsiloxane. This is because it allows the production of a resin substrate 11 that is made from a first resin having short-chain branches containing siloxane-derived structural units and that fully utilizes the effects of including siloxane-derived structural units. As the second oligomer, it is particularly preferable to use a compound represented by the following formula (2) (Silabraine (registered trademark) FM-0721; product name, manufactured by JNC Corporation) that has a structural unit derived from a modified polydimethylsiloxane.

[0064] (In formula (2), n represents the degree of polymerization and is 10 to 150. Me represents —CH ３ n-Bu is —CH ２ CH ２ CH ２ CH ３ It is.)

[0065] As the RAFT agent, it is preferable to use, for example, one having one or more groups represented by the following general formula (11), (21) or (31).

[0066] (In formula (11), Z １ is an alkyl group, and one or more hydrogen atoms in the alkyl group may be substituted with a cyano group, a carboxy group, a methoxycarbonyl group, or an aryl group, and the two or more substituents may be the same or different. ２ is an alkyl group, and Z ３ is an aryl group. ４ is a hydrogen atom or a halogen atom. * in formula (11), (21), or (31) indicates a bond to which the group represented by formula (11), (21), or (31) is bonded.

[0067] As the polymerization initiator used in producing the first resin, for example, one or more known initiators such as persulfates, hydrogen peroxide, azo compounds, and organic peroxides can be used, and it is preferable to use an azo compound such as dimethyl-2,2'-azobis(2-methylpropionate).

[0068] In the above-described method for producing a first resin, the first oligomer and the second oligomer are RAFT polymerized using a RAFT agent, and a crosslinked structure is formed during polymerization, thereby preventing gelation of the resin components. Furthermore, in the above-described method, the first oligomer and the second oligomer are RAFT polymerized, making it possible to easily produce a first resin having a desired degree of polymerization and crosslinked state.

[0069] Furthermore, when the first resin does not have a siloxane-derived structural unit, the first resin can be produced, for example, by the method described below. That is, the first resin can be produced by a method in which one or more monomers selected from a compound having a urethane bond and a polymerizable unsaturated bond, a compound having a fluorene skeleton, and a (meth)acrylic acid alkyl ester are subjected to reversible addition-fragmentation chain transfer polymerization (RAFT polymerization) using a polymerization initiator and a RAFT agent under known conditions. In this case, since one or more monomers are RAFT polymerized using a RAFT agent, a crosslinked structure is formed during polymerization, thereby preventing gelation of the resin components. Furthermore, since the above-mentioned production method involves RAFT polymerization of one or more monomers, a first resin having a desired degree of polymerization and crosslinked state can be easily produced.

[0070] "Filler" Examples of fillers that may be contained in the resin substrate 11 as needed include carbon black, silica, calcium carbonate, talc, and clay. Only one type of filler may be used, or two or more types may be used. The type and shape, such as particle size, of the filler are not particularly limited and can be determined appropriately depending on the application of the resin substrate 11 and the required properties, such as strength and elongation at break.

[0071] When the resin substrate 11 contains a filler, the content of the filler in the resin substrate 11 is, for example, preferably 5 parts by mass to 30 parts by mass, and more preferably 10 parts by mass to 20 parts by mass, per 100 parts by mass of the first resin. When the content of the filler in the resin substrate 11 is 5 parts by mass or more per 100 parts by mass of the first resin, the effect of increasing the Young's modulus of the resin substrate 11 due to the inclusion of the filler is sufficiently obtained. Furthermore, when the content of the filler in the resin substrate 11 is 30 parts by mass or less per 100 parts by mass of the first resin, it is possible to prevent the flexibility of the resin substrate 11 from being impaired due to an excessive filler content.

[0072] The resin substrate 11 is preferably a solidified resin composition containing a first resin, an optional filler, and a solvent. The solvent contained in the resin composition may be any solvent capable of dispersing or dissolving the first resin. Specifically, examples of the solvent include N,N-dimethylacetamide (DMAc), methyl ethyl ketone (MEK), N,N-dimethylformamide (DMF), diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, butyl carbitol, butyl carbitol acetate, ethyl cyanoacrylate, α-terpineol, acetone, ethanol, methanol, ethyl lactate, butyl lactate, toluene, isopropyl alcohol, isobutyl alcohol, ethyl acetate, and butyl acetate. The solvent may be one selected from the above solvents, or two or more may be used. As the solvent, it is preferable to use methyl ethyl ketone (MEK) and / or butyl carbitol acetate, since the first resin is easily dispersed or dissolved in these solvents.

[0073] The resin substrate 11 preferably has a breaking elongation rate of 50% or more, and more preferably 100% or more. When the resin substrate 11 has a breaking elongation rate of 50% or more, the resin wiring board 1 can be suitably used in various stretchable devices such as wearable devices. The breaking elongation rate of the resin substrate 11 can be changed by appropriately selecting the material of the resin substrate 11 and the amount used. Furthermore, the breaking elongation rate of the resin substrate 11 is preferably 3000% or less. This is because the resin substrate 11 has a sufficiently high Young's modulus, and is less likely to suffer from plate release problems even when a wiring pattern 24 is formed on the resin substrate 11 by a printing method.

[0074] In this specification, "elongation at break" is defined as {(length at break - length before pulling) / length before pulling} x 100 (%). The elongation at break can be measured in each predetermined direction. In this specification, for example, "the elongation at break of the resin substrate 11 is 50% or more" specifies that the elongation at break in the direction in which the elongation at break is greatest is 50% or more. If there is no anisotropy in the elongation at break, the elongation at break will be the same in all directions. Furthermore, if the anisotropy of the elongation at break is small, the elongation at break will be close in all directions.

[0075] 1, 2(a) and 2(b), the resin coating layer 31 is laminated on the resin substrate 11 so as to cover the wiring pattern 24 arranged on the first surface 11a of the resin substrate 11. The resin coating layer 31 has stretchability.

[0076] The resin coating layer 31 has a lower Young's modulus and lower strength than the resin substrate 11. The Young's modulus of the resin coating layer 31 is 25 N / mm ２ Preferably, it is 15 N / mm or less. ２ More preferably, it is 5 N / mm or less. ２ It is more preferable that the Young's modulus is 25 N / mm or less. ２ The resin coating layer 31 described below has low strength and excellent adhesion to the wiring pattern 24 and the resin base material 11 , and forms a flexible resin wiring board 1 that is weaker in strength than the resin base material 11 .

[0077] The resin coating layer 31 contains a resin component made of the second resin. The resin coating layer 31 may or may not contain a filler. The filler may be the same as the filler that may be contained in the resin base material 11. It is preferable that the resin coating layer 31 does not contain a filler and is made only of the second resin. This is because the resin coating layer 31 has a low Young's modulus and excellent adhesion to the wiring pattern 24, and the resin base material 11 and the resin coating layer 31 are more resistant to delamination in the resin wiring board 1.

[0078] "Second Resin" The second resin contained in the resin coating layer 31 may be any resin as long as some or all of the structural units derived from a monomer have a common structural unit that is the same as that of the first resin contained in the resin substrate 11. The common structural unit may be only one structural unit or may be two or more structural units.

[0079] Examples of the second resin contained in the resin coating layer 31 include epoxy-based resins, urethane-based resins, urea-based resins, polyurethane-urea-based resins, (meth)acrylic acid-based resins, polyacrylic resins, silicone-based resins, diene-based resins, polyester-based resins, polyether-based resins, polyamide-based resins, and polystyrene-based resins.

[0080] The second resin preferably has, as a structural unit derived from a monomer, one or more structural units selected from a urethane-derived structural unit, a fluorene-derived structural unit, a siloxane-derived structural unit, and a RAFT agent-derived structural unit. Like the first resin, the second resin may or may not contain a (meth)acrylic acid-derived structural unit. However, unlike the first resin, the second resin preferably does not contain a (meth)acrylic acid-derived structural unit. This is because the resin coating layer 31 has a low Young's modulus and excellent adhesion to the wiring pattern 24, and the resin substrate 1 and the resin coating layer 31 are more resistant to delamination.

[0081] The second resin preferably contains one or both of a urethane-derived structural unit and a fluorene-derived structural unit as a structural unit derived from a monomer. This is because a resin coating layer 31 with good flexibility can be obtained, and the resin substrate 1 and the resin coating layer 31 can be made to be even less susceptible to delamination. This is also because a flexible resin wiring board 1 with lower strength than the resin substrate 11 can be easily formed.

[0082] It is more preferable that the second resin contains, as the structural units derived from the monomer, one or both of a urethane-derived structural unit and a fluorene-derived structural unit, and optionally a siloxane-derived structural unit and a RAFT agent-derived structural unit, because this results in a resin wiring board 1 that has better flexibility and is even less susceptible to delamination between the resin substrate 11 and the resin coating layer 31.

[0083] The greater the number of urethane bonds in the resin coating layer 31, the more likely it is that a resin wiring board 1 with excellent flexibility will be obtained. When the second resin contains urethane-derived structural units as structural units derived from monomers, the proportion of urethane-derived structural units among the structural units derived from the monomers contained in the second resin is preferably 3% to 99% by mass. This is because when the proportion of urethane-derived structural units is 3% by mass or more, the effect of including urethane-derived structural units can be fully obtained. Furthermore, when the proportion of urethane-derived structural units is 99% by mass or less, structural units other than urethane-derived structural units can be sufficiently contained. As a result, it is easier to obtain a resin wiring board 1 with better properties suited to its intended use.

[0084] The greater the number of fluorene-derived structural units in the resin coating layer 31, the more likely it is that the resin coating layer 31 will have excellent flexibility and good stretch durability, i.e., stretchability that is resistant to deterioration even when stretched repeatedly. When the second resin contains fluorene-derived structural units as structural units derived from monomers, the proportion of fluorene-derived structural units among the structural units derived from monomers contained in the second resin is preferably 10% to 98% by mass. This is because a proportion of fluorene-derived structural units of 10% by mass or more can sufficiently achieve the effect of improving flexibility and stretch durability due to the inclusion of fluorene-derived structural units. Furthermore, when the proportion of fluorene-derived structural units is 98% by mass or less, structural units other than fluorene-derived structural units, such as urethane-derived structural units, can be sufficiently contained. As a result, it is easier to obtain a resin wiring board 1 with better properties suited to its intended use.

[0085] When the second resin has a siloxane-derived structural unit, the resin coating layer 31 has appropriate water repellency. As a result, the resin coating layer 31 has excellent durability and is inhibited from deterioration over time due to moisture. Furthermore, when the second resin has a siloxane-derived structural unit, the resin coating layer 31 has good tackiness (adhesiveness), and the resin substrate 1 and the resin coating layer 31 are even less susceptible to delamination.

[0086] When the second resin contains a siloxane-derived structural unit as a structural unit derived from a monomer, the proportion of the siloxane-derived structural unit relative to 100 parts by mass of a first oligomer obtained by polymerizing one or more monomers selected from a urethane-derived structural unit, a fluorene-derived structural unit, and a (meth)acrylic acid-derived structural unit by a known method is preferably 0.5% to 10% by mass. This is because a proportion of the siloxane-derived structural unit of 0.5% by mass or more can fully achieve the effects of including the siloxane-derived structural unit. Furthermore, a proportion of the siloxane-derived structural unit of 10% by mass or less can fully include structural units other than the siloxane-derived structural unit. As a result, a resin coating layer 31 having better properties corresponding to the intended use of the resin wiring board 1 can be more easily obtained.

[0087] When the second resin has urethane-derived structural units as well as siloxane-derived structural units, the urethane bonds in the resin coating layer 31 are less susceptible to hydrolysis, resulting in a resin coating layer 31 in which deterioration over time due to hydrolysis is suppressed. When the second resin has urethane-derived structural units as well as siloxane-derived structural units, the greater the number of siloxane bonds in the resin coating layer 31, the less susceptible the urethane bonds in the resin coating layer 31 are to hydrolysis, resulting in a resin wiring board 1 with excellent durability. When the second resin has urethane-derived structural units as well as siloxane-derived structural units, the ratio of the number of urethane bonds to the number of siloxane bonds contained in the second resin is not particularly limited and can be determined appropriately depending on the application of the resin wiring board 1 and the properties such as the required durability and elongation at break.

[0088] The second resin preferably has a different proportion of common structural units, which are structural units derived from monomers contained in the second resin and are the same as the structural units derived from monomers contained in the first resin, from that of the first resin. The reason for this is that it is easier to obtain a resin coating layer 31 having a lower Young's modulus than the resin substrate 11. When there are two or more common structural units, a different proportion of the common structural units means that the proportion of at least one structural unit is different among the two or more common structural units.

[0089] The common structural unit preferably includes one or both of a structural unit derived from a compound having a urethane bond and a polymerizable unsaturated bond and a structural unit derived from a compound having a fluorene skeleton. This is because the resin substrate 11 can be formed with a sufficiently high Young's modulus, and even when a wiring pattern 24 is formed on the resin substrate 11 by a printing method, the resin diffusion layer 23 can be easily formed, and a resin wiring board 1 that is resistant to delamination can be obtained by forming a resin coating layer 31 on the resin substrate 11 using the method described below.

[0090] The second resin can be produced, for example, by the method described below. First, a first oligomer is produced by polymerizing, by a known method, one or more monomers selected from a compound having a urethane bond and a polymerizable unsaturated bond and a compound having a fluorene skeleton, the one or more monomers being the same as the monomers used in producing the first resin. A second oligomer is then produced by polymerizing, by a known method, a compound having a siloxane bond and a polymerizable unsaturated bond, which may be the same as the compound used in producing the first resin. The second resin can then be produced by reversible addition-fragmentation chain transfer polymerization (RAFT polymerization) under known conditions using the first oligomer, the second oligomer, a polymerization initiator, and a RAFT agent. This production method is preferred because it facilitates the production of a second resin having a skeleton composed of a polymer of the first oligomer and short-chain branches containing structural units derived from a compound having a siloxane bond and a polymerizable unsaturated bond.

[0091] The second resin may be produced by a method of reversible addition-fragmentation chain transfer polymerization (RAFT polymerization) under known conditions using a compound having a urethane bond and a polymerizable unsaturated bond, a compound having a fluorene skeleton, a compound having a siloxane bond and a polymerizable unsaturated bond, a polymerization initiator, and a RAFT agent.

[0092] The monomer used as a raw material in producing the second resin contains one or more of the same compounds as those contained in the monomer used as a raw material in producing the first resin. In this embodiment, it is preferable that the content of the one or more compounds used as raw materials in both the first resin and the second resin differs between the first resin and the second resin.

[0093] The resin coating layer 31 is preferably formed by solidifying a resin composition containing the second resin and a solvent. The solvent contained in the resin composition used to form the resin coating layer 31 is one that can disperse or dissolve the first resin and the second resin. Examples of the solvent contained in the resin composition used to form the resin coating layer 31 include those that can be used as solvents contained in the resin composition used to form the resin substrate 11.

[0094] (Wiring Pattern 24) As shown in Figures 1, 2(a), and 2(b), the wiring pattern 24 is a linear wiring having a substantially rectangular cross-sectional shape and disposed on the first surface 11a of the resin base material 11. As shown in Figure 2(b), the wiring pattern 24 is disposed between the resin base material 11 and the resin coating layer 31. Furthermore, the wiring pattern 24 is formed so that a first surface 24a (the lower surface in Figure 2(b)) is in contact with the resin base material 11, and a second surface 24b (the upper surface in Figure 2(b)) opposite the first surface 24a is in contact with the resin coating layer 31.

[0095] In this embodiment, an example of the wiring pattern 24 is described as having a substantially rectangular cross-sectional shape, but the cross-sectional shape of the wiring pattern 24 is not limited to a substantially rectangular shape and may be, for example, a substantially elliptical shape.

[0096] The planar shape of the wiring pattern 24 is not particularly limited and can be determined appropriately depending on the application of the resin wiring board 1. The planar shape of the wiring pattern 24 is preferably a shape that is resistant to breakage and peeling even when the resin base material 11 is deformed, and can be, for example, a curved shape in which successive arcs having a predetermined radius of curvature are connected, as shown in Fig. 1. The number of wiring patterns 24 can be determined appropriately depending on the application of the resin wiring board 1.

[0097] The wiring pattern 24 is preferably made of a conductive resin containing metal powder and a stretchable resin, because the wiring pattern 24 is flexible and is less likely to break or peel off even if the resin wiring board 1 is deformed.

[0098] The stretchable resin contained in the conductive resin forming the wiring pattern 24 can be a known stretchable resin. In this embodiment, it is preferable to use a resin as the stretchable resin, in which some or all of the structural units derived from the monomer are common structural units contained in both the first resin and the second resin described above. The common structural unit may be only one structural unit, or may be two or more structural units. In other words, it is preferable that the conductive resin forming the wiring pattern 24 contains a common structural unit, and it is particularly preferable that the stretchable resin contained in the conductive resin is the second resin described above. This is because the wiring pattern 24 has good adhesion to the resin substrate 11 and the resin coating layer 31 and has good flexibility.

[0099] The content of the elastic resin contained in the wiring pattern 24 is preferably in the range of 8% by mass to 20% by mass, and more preferably in the range of 10% by mass to 18% by mass. When the content of the elastic resin contained in the wiring pattern 24 is 8% by mass or more, the wiring pattern 24 has good elasticity and excellent adhesion to the resin substrate 11 and the resin coating layer 31. When the content of the elastic resin contained in the wiring pattern 24 is 20% by mass or less, it is easy to ensure the content of metal powder in the wiring pattern 24, and therefore it is easy to obtain a wiring pattern 24 with high conductivity, which is preferable.

[0100] The metal powder contained in the wiring pattern 24 is not particularly limited, and known metal powders can be used. The metal powder preferably contains scale-shaped (flake-shaped) powder. When the metal powder contains scale-shaped powder, the scale-shaped powder has upper and lower surfaces that extend in the planar direction, which increases the proportion of surface contact between the metal powder particles, thereby achieving high conductivity (low resistivity).

[0101] In this specification, "scale-shaped powder" refers to powder (metal powder) whose thickness is 1 / 10 or less of the maximum particle diameter. The maximum particle diameter of scale-shaped powder is determined as follows. The length from end to end of each scale-shaped powder varies depending on the direction in a plan view, and the longest of these lengths is defined as the maximum particle diameter. The maximum particle diameter can be determined by methods such as observation with an optical microscope or scanning electron microscope (SEM) (for example, a 5000x field of view).

[0102] Examples of the metal powder contained in the wiring pattern 24 include silver (Ag) powder, carbon (C) powder, copper (Cu) powder, palladium (Pd) powder, gold (Au) powder, platinum (Pt) powder, etc. Among these, it is preferable to use silver powder or an alloy powder containing silver as a main component as the metal powder, since this results in a wiring pattern 24 with low resistance and excellent conductivity.

[0103] In this specification, "alloy powder containing silver as a main component" means an alloy powder containing more than 50 wt% of silver. The alloy powder containing silver as a main component preferably contains 70 wt% or more of silver, more preferably 80 wt% or more of silver, and even more preferably 90 wt% or more of silver. The silver powder may also be silver powder whose surface is silver and whose interior is made of a metal other than silver, such as silver-coated copper powder.

[0104] The metal powder may be prepared as needed or commercially available. Examples of methods for producing particulate silver powder include adding a reducing agent-containing aqueous solution to an aqueous reaction system containing silver ions to reduce and precipitate silver particles. Furthermore, flake-shaped metal powder can be produced, for example, by forming a thin film of the desired metal and then pulverizing the thin film. Since the flake-shaped powder produced by this method is obtained by pulverizing the thin film, the individual crushed metal flakes are also flat. The thickness (i.e., the degree of flatness) relative to the maximum particle diameter of the flake-shaped powder can be adjusted by adjusting the thickness of the thin film used as the material and the degree of pulverization.

[0105] (Resin Diffusion Layer 23) As shown in FIG. 2(b), the resin diffusion layer 23 is disposed between the resin substrate 11 and the resin coating layer 31, at least in a region that does not overlap with the wiring pattern 24 in a planar view. As shown in FIG. 2(b), the resin diffusion layer 23 is formed with a substantially constant thickness in a region that does not overlap with the wiring pattern 24 in a planar view, with the position of the first surface 24a of the wiring pattern 24 being approximately the center in the thickness direction in a cross-sectional view. Furthermore, as shown in FIG. 2(b), the resin diffusion layer 23 is also formed on the first surface 24a that is along the side surface of the wiring pattern 24. Furthermore, as shown in FIG. 2(b), the resin diffusion layer 23 is not formed in the central portions of the first surface 24a and the second surface 24b of the wiring pattern 24 in a planar view.

[0106] The resin diffusion layer 23 only needs to be arranged in an area that does not overlap with the wiring pattern 24 in a planar view, and may also be formed on the second surface 24b along the side surface of the wiring pattern 24, or, as shown in Figure 2 (b), it does not need to be formed on the second surface 24b along the side surface of the wiring pattern 24.

[0107] The resin diffusion layer 23 includes a resin component made of a third resin. The third resin forming the resin diffusion layer 23 includes all of the common structural units contained in both the first resin and the second resin, some or all of which are derived from monomers. That is, the first resin contained in the resin substrate 11, the second resin contained in the resin coating layer 31, and the third resin forming the resin diffusion layer 23 all have the same common structural units, some or all of which are derived from monomers. Therefore, the resin diffusion layer 23 adheres the resin substrate 11 and the resin coating layer 31 together, making delamination between the resin substrate 11 and the resin coating layer 31 less likely to occur.

[0108] In the resin wiring board 1 of this embodiment, the first resin, the second resin, and the third resin have different proportions of common structural units contained in the structural units derived from the monomers. Specifically, the proportion of the common structural units in the third resin is a value between the proportions of the common structural units in the first resin and the proportions of the common structural units in the second resin, and changes continuously or stepwise in the thickness direction of the resin diffusion layer 23.

[0109] For example, when the common structural unit is one or both of a structural unit derived from a compound having a urethane bond and a polymerizable unsaturated bond and a structural unit derived from a compound having a fluorene skeleton, the Young's modulus of the resin coating layer 31 is likely to be lower than that of the resin substrate 11. Therefore, the proportions of the common structural units in the first resin, the second resin, and the third resin are preferably as follows: That is, the first resin is low, the third resin is higher than the first resin, and the second resin is higher than the third resin. In this case, the proportion of the common structural unit in the third resin forming the resin diffusion layer 23 is lower on the resin substrate 11 side and higher on the resin coating layer 31 side, either continuously or stepwise, in the thickness direction of the resin diffusion layer 23.

[0110] In the resin wiring board 1 of this embodiment, the resin diffusion layer 23 containing a resin component made of a third resin different from the first resin and the second resin is present between the resin base material 11 (first resin layer) and the resin coating layer 31 (second resin layer), and the first resin contained in the first resin layer, the second resin contained in the second resin layer, and the third resin contained in the resin diffusion layer have some or all of the structural units derived from monomers that are the same, for example, by the method shown below.

[0111] That is, the resin wiring board 1 is analyzed by photothermal infrared spectroscopy (O-PTIR) using an infrared spectroscopic analyzer. More specifically, a region including the resin base material 11 (first resin layer) and the resin coating layer 31 (second resin layer) of the resin wiring board 1 is subjected to mapping measurement at intervals of, for example, 1 μm in the thickness direction of the laminate by photothermal infrared spectroscopy, and multiple infrared absorption (IR) spectra are obtained.

[0112] Then, from the multiple IR spectra, a first IR spectrum having a peak that can confirm that it is the first resin layer and a second IR spectrum having a peak that can confirm that it is the second resin layer are obtained. After that, it is confirmed whether there is an IR spectrum that can confirm that it is neither the first resin layer nor the second resin layer between the first IR spectrum and the second IR spectrum at a position in the thickness direction of the laminate. This makes it possible to confirm whether the resin wiring board 1 has a resin diffusion layer 23.

[0113] Furthermore, if there is an IR spectrum between the first IR spectrum and the second IR spectrum that can be identified as neither the first nor the second resin layer, it is confirmed whether the IR spectrum, the first IR spectrum, and the second IR spectrum have peaks at a common wavelength, which makes it possible to confirm whether the first resin contained in the first resin layer, the second resin contained in the second resin layer, and the third resin contained in the resin diffusion layer 23 have the same structural units derived from some or all of the monomers.

[0114] In multiple IR spectra obtained by performing mapping measurements at 1 μm intervals in the thickness direction of the laminate using photothermal conversion infrared spectroscopy, peak intensities derived from the monomer contained in the first resin forming the first resin layer that differ by 10% or more in peak area ratio are not considered to be the first resin layer, and peaks that differ by less than 10% in peak area ratio are considered to be the first resin layer. Also, in multiple IR spectra obtained by performing mapping measurements at 1 μm intervals in the thickness direction of the laminate using photothermal conversion infrared spectroscopy, peak intensities derived from the monomer contained in the second resin forming the second resin layer that differ by 10% or more in peak area ratio are not considered to be the second resin layer, and peaks that differ by less than 10% in peak area ratio are considered to be the second resin layer.

[0115] (Electronic Components 41) In the stretchable device of this embodiment, two electronic components 41 are arranged on the first surface 11a of the resin base material 11 of the resin wiring board 1. These electronic components 41 are electrically connected to the wiring patterns 24 shown in Figures 1, 2(a) and 2(b), respectively. The number and types of electronic components 41 are not particularly limited and are determined appropriately depending on the application of the stretchable device.

[0116] Known electronic components can be used as the electronic component 41. Examples of the electronic component 41 include various sensors, capacitors, inductors, high-frequency filters, transformers, resistors, varistors, diodes, various ICs, various actuators, antennas, and batteries. When the electronic component 41 is a battery, examples include a solar cell, a lithium-ion battery, and an electric double-layer capacitor. Examples of the solar cell include a double-sided electrode solar cell and a back-side electrode solar cell in terms of electrode arrangement. Furthermore, examples of the solar cell include inorganic material solar cells such as silicon-based solar cells and compound semiconductor-based solar cells, and organic solar cells in terms of materials.

[0117] [Method for manufacturing a stretchable device] Next, an example of a method for manufacturing a stretchable device shown in Figures 1, 2(a), and 2(b) will be described in detail with reference to the drawings. In this embodiment, first, a resin wiring substrate 1 is manufactured. Figures 3(a) to 3(c) are process diagrams for explaining an example of a method for manufacturing the stretchable device shown in Figure 1. Figures 3(a) to 3(c) are cross-sectional schematic views showing enlarged regions corresponding to part of a cross section in a direction perpendicular to the longitudinal direction of the resin substrate 11 shown in Figure 1.

[0118] (Formation of Resin Substrate 11) First, a resin composition containing the above-described first resin, a filler optionally contained, and a solvent is prepared using a known method. Next, the resin composition is applied to a manufacturing substrate (not shown) in a predetermined planar shape and thickness to form a resin composition layer having a strip-like shape corresponding to the planar shape of the resin substrate 11 (coating step). In the coating step, a known method can be used as a method for applying the resin composition. Specifically, as the coating method, for example, a method using various coaters or wire bars, or various printing methods including inkjet printing can be used.

[0119] Next, the resin composition layer is dried and solidified (drying and solidifying step). This results in a sheet-like resin substrate 11. In the drying and solidifying step, the drying temperature for drying the resin composition layer is, for example, preferably 25°C or higher and 150°C or lower, and more preferably 25°C or higher and 120°C or lower. When the drying temperature is 25°C or higher, the resin composition layer can be dried more efficiently, and the sheet-like resin substrate 11 can be efficiently produced. When the drying temperature is 150°C or lower, deterioration of the sheet-like resin substrate 11 due to an excessively high drying temperature can be suppressed.

[0120] In the drying and solidifying step, completion of solidification by drying the resin composition layer can be confirmed, for example, by the fact that no clear change in the mass of the resin composition layer being dried is observed. Next, in this embodiment, the sheet-like resin substrate 11 is peeled off from the manufacturing substrate (see FIG. 3( a)).

[0121] (Formation of wiring pattern 24) Next, in this embodiment, an expandable electrical wiring paste containing a resin composition including the above-mentioned second resin and a solvent, and a predetermined amount of metal powder such as silver powder, is used to form the wiring pattern 24 on the resin substrate 11. As the expandable electrical wiring paste, it is preferable to use one that contains 50% by mass to 90% by mass of metal powder relative to the content of resin in the expandable electrical wiring paste, for example.

[0122] First, the stretchable electrical wiring paste is printed on the resin substrate 11 in a shape corresponding to the planar shape of the wiring pattern 24 to form a wiring paste layer of a predetermined thickness (printing step). In the printing step, various printing methods including inkjet printing can be used as a method for printing the stretchable electrical wiring paste.

[0123] Next, the wiring paste layer is dried and solidified (drying and solidifying step). This results in the wiring pattern 24. In the drying and solidifying step, the drying temperature for drying the wiring paste layer is, for example, preferably 25°C or higher and 150°C or lower, and more preferably 25°C or higher and 120°C or lower. If the drying temperature is 25°C or higher, the wiring paste layer can be dried more efficiently, and the wiring pattern 24 can be produced efficiently. If the drying temperature is 150°C or lower, deterioration of the resin substrate 11 and the wiring pattern 24 due to an excessively high drying temperature can be suppressed.

[0124] In the drying and solidifying step, completion of solidification by drying the wiring paste layer can be confirmed, for example, by the absence of any clear change in the mass of the wiring paste layer being dried. Through the above steps, an elastic linear wiring pattern 24 is formed on the first surface 11 a of the resin substrate 11 (see FIG. 3( b)).

[0125] (Formation of resin coating layer 31 and resin diffusion layer 23) Next, in this embodiment, a resin composition containing the above-mentioned second resin and solvent is used to form an elastic resin coating layer 31 and a resin diffusion layer 23 on the first surface 11a of the resin substrate 11 having the wiring pattern 24.

[0126] First, a resin composition containing the second resin and a solvent is prepared using a known method. The concentration of the second resin contained in the resin composition can be, for example, 0.5% by mass to 6% by mass, preferably 1% by mass to 4% by mass. When the concentration of the second resin is 0.5% by mass or more, the resin coating layer 31 can be easily formed by applying and drying the resin composition. Furthermore, when the concentration of the second resin is 6% by mass or less, a resin wiring board 1 is easily formed that has excellent adhesion between the resin substrate 11 and the resin coating layer 31 and is less susceptible to delamination between the resin substrate 11 and the resin coating layer 31. This is presumably because the first resin forming the surface of the resin substrate 11 is sufficiently eluted into the solvent contained in the resin composition applied to the resin substrate 11, resulting in the formation of a resin diffusion layer 23 with sufficient thickness.

[0127] Next, the resin composition is applied to the first surface 11a of the resin substrate 11 having the wiring pattern 24 in a predetermined planar shape and thickness to form a resin composition layer having a predetermined thickness (application step). In the application step, the resin composition can be applied by a method similar to that used when forming the resin substrate 11.

[0128] In this embodiment, it is preferable to apply a resin composition containing a second resin and a solvent to the first surface 11a of the resin substrate 11 while heating the resin substrate 11 having the wiring pattern 24. This makes it easier for the first resin forming the surface of the resin substrate 11 to dissolve into the solvent contained in the resin composition applied to the resin substrate 11, making it easier to form a resin diffusion layer 23 with a sufficient thickness. In this embodiment, it is more preferable to heat the resin substrate 11 having the wiring pattern 24 to a predetermined temperature, and then apply a resin composition containing a second resin and a solvent to the first surface 11a of the resin substrate 11 while maintaining the predetermined temperature. Methods for heating the resin substrate 11 include, for example, placing the resin substrate 11 on a hot plate and heating the resin substrate 11 in the drying chamber of a dryer. The temperature to which the resin substrate 11 is heated when applying the resin composition can be, for example, 70°C to 100°C, and can be determined appropriately depending on the type of resin substrate 11, the type of solvent contained in the resin composition, the amount of resin composition applied, and the like.

[0129] Next, the resin composition layer is dried and solidified (drying and solidification step) in the same manner as in forming the resin substrate 11. This forms a resin coating layer 31 that covers the wiring pattern 24, and also forms a resin diffusion layer 23 in a region between the resin substrate 11 and the resin coating layer 31 that does not overlap with the wiring pattern 24 in a planar view.

[0130] In the drying and solidification step, the drying temperature for drying the resin composition layer is preferably 25°C or higher and 150°C or lower, and more preferably 25°C or higher and 120°C or lower, as in the case of forming the resin substrate 11. If the drying temperature is 25°C or higher, the first resin forming the surface of the resin substrate 11 is likely to dissolve into the solvent contained in the resin composition applied to the resin substrate 11. If the drying temperature is 25°C or higher, the resin composition layer can be dried more efficiently, and the resin diffusion layer 23 and the resin coating layer 31 can be efficiently produced. If the drying temperature is 150°C or lower, deterioration of the resin substrate 11 and the resin coating layer 31 having the wiring pattern 24 due to an excessively high drying temperature can be suppressed.

[0131] In the drying and solidifying step, completion of solidification by drying the resin composition layer can be confirmed, for example, by the fact that no clear change in the mass of the resin composition layer being dried is observed.

[0132] (Mounting of Electronic Component 41) Next, in this embodiment, the electronic component 41 is placed at a predetermined position on the first surface 11a of the resin substrate 11 having the resin coating layer 31 and the wiring pattern 24 by a known method such as a method using a surface mounter. Then, the electronic component 41 and the wiring pattern 24 are electrically connected by a known method using molten solder, a conductive adhesive, an anisotropic adhesive, or the like. By performing the above steps, the stretchable device of this embodiment is obtained.

[0133] [Other Examples] The above describes the embodiments of the present invention in detail, but each configuration and combination thereof in each embodiment is merely an example, and additions, omissions, substitutions, and other modifications of the configurations are possible within the scope that does not deviate from the spirit of the present invention.

[0134] For example, in the above-described stretchable device, as shown in FIGS. 1 and 2(b), the case has been described as an example in which the surface of the electronic component 41 opposite the resin substrate 11 and the portion of the wiring pattern 24 electrically connected to the electronic component 41 that is not covered by the resin coating layer 31 are exposed, but the electronic component 41 and the wiring pattern 24 may be covered by a resin coating layer.

[0135] The resin coating layer that coats the electronic components 41 and the wiring pattern 24 can be made of a known material, and preferably contains an elastic resin. The elastic resin contained in the resin coating layer that coats the electronic components 41 and the wiring pattern 24 can be the same as the first resin that forms the resin substrate 11. The elastic resin contained in the resin coating layer that coats the electronic components 41 and the wiring pattern 24 may be the same as or different from the resin that forms the resin substrate 11 and / or the resin coating layer 31, and preferably they are the same.

[0136] The present invention will be described in more detail below with reference to examples and comparative examples. The present invention is not limited to the following examples. [Resin Compositions 1 to 8] A siloxane shown in Table 1 was mixed with a monomer mixture obtained by mixing urethane, fluorene, and methacrylic acid in the ratios shown in Table 1, in the ratios shown in Table 1 (parts by mass relative to 100 parts by mass of the monomer mixture). The mixture was then heated in methyl ethyl ketone (MEK) to undergo reversible addition-fragmentation chain transfer polymerization (RAFT polymerization) using 1.0 part by mass of dimethyl-2,2'-azobis(2-methylpropionate) (V601; product name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a polymerization initiator relative to 100 parts by mass of the total monomers, and 1.5 parts by mass of a RAFT agent (S,S-dibenzyltrithiocarbonate; manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) relative to 100 parts by mass of the total monomers, to obtain a resin.

[0137] The resulting resin was mixed with the filler shown in Table 1 in the ratio (parts by mass relative to 100 parts by mass of resin) shown in Table 1, and dispersed in MEK as a solvent to prepare Resin Compositions 1 to 8, each having a resin content of 90% by mass to 100% by mass.

[0138]

[0139] The urethane, fluorene, methacrylic acid, siloxane, and filler shown in Table 1 are as follows: [Urethane (resin compositions 1 to 7)] A random copolymer represented by formula (1) (weight average molecular weight (Mw) 61,000, number average molecular weight (Mn) 30,800). [Urethane (resin composition 8)] A random copolymer represented by formula (12) (n in formula (12) １ is 35. R １１ is -(CH ２ ) ４０ - is. R １２ is -CH ２ CH (CH ２ ) ８０ CH ３ The weight average molecular weight (Mw) is 75,000 and the number average molecular weight (Mn) is 40,000.

[0140] [Fluorene] GA-2800 (trade name; manufactured by Osaka Gas Chemicals Co., Ltd.). [Methacrylic acid] Methyl methacrylate (manufactured by Kuraray Co., Ltd.). [Siloxane] A compound having a structural unit derived from modified polydimethylsiloxane represented by formula (2) (Silabraine (registered trademark) FM-0721; trade name; manufactured by JNC Corporation). [Filler] Silica, average particle size 2.1 μm to 2.6 μm (manufactured by Tosoh Silica Corporation).

[0141] Resin compositions 1 to 8 thus obtained were used to form resin substrates 1 to 8 by the method described below. Resin compositions 1 to 8 were each applied to a manufacturing substrate made of a PET film using a coater, and then dried at 80°C to solidify, thereby obtaining resin substrates 1 to 8 in the form of sheets having a thickness of 0.05 mm.

[0142] Resin substrates 1 to 8 obtained in this manner were peeled from the manufacturing substrate, and the Young's modulus, elongation at break, strength, and printing plate release were each examined using the methods described below. The results are shown in Table 2. In the methods described below, the Young's modulus, elongation at break, and strength of the resin substrate were measured at a measurement point of 10 mm width and 10 mm length, but the measurement results for the Young's modulus, elongation at break, and strength of the resin substrate were similar regardless of the dimensions of the measurement point. Therefore, the dimensions of the measurement point for the above items of the resin substrate may be, for example, 5 mm width and 5 mm length, or 3 mm width and 3 mm length.

[0143] [Measurement of Young's Modulus] Five strip-shaped measurement samples, each 10 mm wide and 35 mm long, were cut out from the resin substrate. A metal substrate was clamped between the upper and lower grips of the measuring instrument, and the measurement sample was fixed to the metal substrate with double-sided tape so that the measurement point was 10 mm wide and 10 mm long. Thereafter, the tensile stress and strain of the measurement sample were measured using a tensile tester (product name: Autograph AGS-5kNX, manufactured by Shimadzu Corporation). Using the results, a stress-strain diagram was created, and the Young's modulus of the measurement sample was calculated from the slope of the proportional limit. The average value of the Young's moduli of the five measurement samples was taken as the Young's modulus of each resin substrate.

[0144] [Measurement of Breaking Elongation] Six strip-shaped measurement samples, each 10 mm wide and 30 mm long, were cut out from each resin substrate. The elongation at break of each measurement sample was calculated by the method described below.

[0145] The metal substrate was clamped between the upper and lower grips of the measuring instrument, and the measurement sample was fixed to the metal substrate with double-sided tape so that the measurement point was 10 mm wide and 10 mm long. The measurement sample was then pulled at a pulling rate of 10 mm / min using a tensile tester (product name: Autograph AGS-5kNX, manufactured by Shimadzu Corporation). The length of the measurement sample at break was measured, and the length before pulling (10 mm) was subtracted from that length to calculate the elongation at break (length at break - length before pulling) for each measurement sample. The average value was taken as the elongation at break, and the elongation at break was calculated using the following formula: Elongation at break (%) = {elongation at break / length before pulling} × 100

[0146] [Strength Measurement] Five strip-shaped measurement samples, each 10 mm wide and 35 mm long, were cut out from the resin substrate. The maximum tensile strength of each measurement sample was calculated using the method described below, and the average value was used as the strength. A metal substrate was clamped between the upper and lower grips of the measuring device, and the measurement sample was fixed to the metal substrate with double-sided tape so that the measurement point was 10 mm wide and 10 mm long. The measurement sample was then pulled at a pulling rate of 10 mm / min using a tensile tester (product name: Autograph AGS-5kNX, manufactured by Shimadzu Corporation). The maximum tensile strength of the measurement sample was then measured.

[0147] [Measurement of printing plate release] A wiring paste was prepared containing a resin composition containing a resin composed of urethane, methacrylic acid, and acrylic acid, and solvents diethylene glycol monobutyl ether (BC), diethylene glycol monobutyl ether acetate (BCA), and diethylene glycol monoethyl ether acetate (ECA), and silver powder, with the silver powder content being 65% by mass relative to the resin content. The obtained wiring paste was printed on a resin substrate by screen printing and dried at 80°C to solidify, forming a wiring pattern with a width of 200 μm and a thickness of 10 μm. The pattern was evaluated according to the following criteria.

[0148] (Criteria) A: No problem with forming the wiring pattern. B: The mask used for printing does not come off the resin substrate, making it impossible to form a wiring pattern of the desired shape, and / or there is significant bleeding of the wiring pattern caused by stringiness of the wiring paste, etc.

[0149]

[0150] The flexible Kapton and PET shown in Table 2 are as follows: [Flexible Kapton] A 0.025 mm thick sheet made of polyimide (manufactured by DuPont-Toray Co., Ltd.) [PET] A 0.075 mm thick sheet made of polyethylene terephthalate (manufactured by TDK Corporation).

[0151] As shown in Tables 1 and 2, resin substrates 1, 2, 6, 7, and 8, which used resin compositions 1, 2, 6, 7, and 8 using urethane and / or fluorene as the monomer, had lower Young's moduli than resin substrates 4 and 5, which used resin compositions 4 and 5 using methacrylic acid as the monomer. As shown in Table 2, resin substrates 1, 2, and 6, which had particularly low Young's moduli of less than 1, were evaluated as "B" in terms of printing plate release.

[0152] Furthermore, as shown in Tables 1 and 2, resin substrates 1, 4, 5, and 6, which used resin compositions 1, 4, 5, and 6 containing 50% by mass or more of urethane as a monomer, had high elongation at break. In contrast, as shown in Table 2, although the printing plate release rating of [Flexible Kapton][PET] was "A," the elongation at break was very low. Furthermore, as shown in Tables 1 and 2, resin substrates 4 and 5, which used resin compositions 4 and 5 containing methacrylic acid as a monomer, had high strength.

[0153] [Test Examples 1 to 20] In the same manner as in the above resin substrate, a second resin layer was formed using resin composition 1 or resin composition 2 shown in Table 1 on a first resin layer having a thickness of 0.05 mm formed using any of resin compositions 1 to 8 shown in Table 1, or on [Flexible Kapton][PET] shown in Table 2, by the method shown below, to obtain laminates of Test Examples 1 to 20.

[0154] The first resin layer, or the [Flexible Kapton][PET] shown in Table 2, was placed on a hot plate and heated to 100°C. While maintaining the temperature at 100°C, Resin Composition 1 or Resin Composition 2 shown in Table 1, which is a resin composition containing a second resin and a solvent, was applied to the first surface of the first resin layer or the [Flexible Kapton][PET] using a coater. The first resin layer or [Flexible Kapton][PET] coated with Resin Composition 1 or Resin Composition 2 was dried on a hot plate at a temperature of 80°C to solidify the resin composition. As a result, a second resin layer with a thickness of 0.05 mm was formed on the first surface of the first resin layer or the [Flexible Kapton][PET], and the laminates of Test Examples 1 to 20 were obtained.

[0155] The thus obtained laminates of Test Examples 1 to 20 were evaluated for "dispenser application" and "adhesion" between the first resin layer and the second resin layer by the methods described below. The results are shown in Table 3.

[0156] "Dispenser application" The wiring paste used in measuring the above-mentioned printing plate release was placed in the nozzle of a dispenser for forming a wiring pattern (MS-1; manufactured by Musashi Engineering Co., Ltd.). The wiring paste was applied to the second resin layer of the laminate using compressed air to create a wiring pattern with a width of 500 μm and a thickness of 30 μm, and evaluated according to the following criteria.

[0157] (Criteria) A: No bleeding of the wiring pattern, no twisting or distortion of the laminate. B: One or more of bleeding of the wiring pattern, twisting of the laminate, and distortion of the laminate occurred.

[0158] "Adhesion" Three strip-shaped measurement samples, each 10 mm wide and 20 mm long, were cut out from the laminate. For each measurement sample, adhesive tape (trade name: NITTO TAPE; manufactured by Nitto Denko Corporation) was attached to the surface of the laminate facing the second resin layer, and then the adhesive tape was peeled off. This was used to check whether peeling occurred at the interface between the first resin layer and the second resin layer of the laminate, and the adhesion was evaluated according to the following criteria.

[0159] (Criteria) A: No peeling at the interface between the first resin layer and the second resin layer in all three measurement samples. B: Peeling at the interface between the first resin layer and the second resin layer in one or more of the three measurement samples.

[0160]

[0161] As shown in Table 3, Test Examples 3 to 5, 12 to 14, 19, and 20, in which both the first and second resin layers used a resin composition containing [urethane] and the Young's modulus of the second resin layer was lower than that of the first resin layer, and Test Example 16, in which both the first and second resin layers used a resin composition containing [fluorene] and the Young's modulus of the second resin layer was lower than that of the first resin layer, all had good adhesion and were rated "A" for "dispenser application." Moreover, as shown in Table 2, Test Examples 3 to 5, 12 to 14, and 16 used a resin composition in which the first resin layer was rated "A" for printing plate release, and a wiring pattern could be formed on the first resin layer by a printing method.

[0162] Furthermore, although Test Examples 1, 2, 6, 10, 11, 15, 19, and 20 had good adhesion, as shown in Table 2, the first resin layer used a resin composition that was rated "B" for printing plate release, making it difficult to form a wiring pattern on the first resin layer by a printing method. Furthermore, Test Examples 8, 9, 17, and 18 are presumed to have insufficient adhesion because the first resin layer and the second resin layer did not have common structural units in which some or all of the structural units derived from the monomer were the same.

[0163] Furthermore, as shown in Table 3, in Test Examples 1 and 11, the first resin layer and the second resin layer were formed using the same resin composition, and both the first resin layer and the second resin layer had a low Young's modulus. Therefore, in Test Examples 1 and 11, the synergistic effect of having the first resin layer and the second resin layer was not obtained, the flexibility and adhesion of the first resin layer and the second resin layer were very high, and the resin was likely to diffuse between the first resin layer and the second resin layer. As a result, in Test Examples 1 and 11, when "dispenser coating" was performed on the second resin layer, bleeding of the wiring pattern was likely to occur, and kinking was likely to occur near the wiring pattern of the laminate, which is presumably why the "dispenser coating" evaluation was "B."

[0164] Test Example 21 In the same manner as in the above-described resin substrate 4, a first resin layer having a thickness of 40 μm was formed using resin composition 4 shown in Table 1. Thereafter, in the same manner as in Test Example 13, a second resin layer having a thickness of 40 μm was formed on the first resin layer using resin composition 2 shown in Table 1, thereby obtaining a laminate of Test Example 21.

[0165] The laminate of Test Example 21 thus obtained was analyzed by photothermal infrared spectroscopy (O-PTIR) using an infrared spectrometer (trade name: mIRage, manufactured by Japan Thermal Consulting Co., Ltd.) The results are shown in FIGS.

[0166] Fig. 4 is an image of the cross section of the laminate of Test Example 21, photographed using a camera provided in an infrared spectrometer. Mapping measurements were performed at 1-µm intervals in the thickness direction of the laminate by photothermal conversion infrared spectroscopy for a 10.1 µm region in the thickness direction (the region surrounded by the rectangle in the image shown in Fig. 4 ), including the first resin layer (the lower layer in Fig. 4 ) and the second resin layer (the upper layer in Fig. 4 ), to obtain ten infrared absorption (IR) spectra as shown in Fig. 5 .

[0167] The wavelength of the IR spectrum shown in FIG. －１ ±35cm －１ , wavelength 1500cm －１ ±35cm －１ , wavelength 1600cm －１ ±35cm －１ The peak at a wavelength of 1150 cm in the IR spectrum shown in FIG. 5 is derived from fluorene contained only in the first resin layer (the upper layer in FIG. 4) of the laminate. These peaks can be clearly seen in the sixth IR spectrum from the top in FIG. 5. －１ ±35cm －１ The peak at wavelength 1150 cm is derived from methacrylic acid contained only in the second resin layer (the lower layer in FIG. 4) of the laminate. －１ ±35cm －１ The peaks can be clearly seen in the fifth IR spectrum from the bottom shown in FIG.

[0168] In addition, the wavelength of the IR spectrum shown in FIG. －１±35cm －１ , wavelength 1741cm －１ ±25cm －１ The peak at a wavelength of 1260 cm is derived from C═O contained in the first resin layer and the second resin layer of the laminate. －１ ±35cm －１ , wavelength 1741cm －１ ±25cm －１ The peak at a wavelength of 1260 cm is derived from the urethane contained in the first resin layer and the second resin layer and the methacrylic acid contained in the first resin layer. －１ ±35cm －１ , wavelength 1741cm －１ ±25cm －１ The peaks are clearly visible in all the IR spectra shown in FIG.

[0169] As shown in FIG. 5, the wavelength of the IR spectrum is 1114 cm －１ ±35cm －１ , wavelength 1150cm －１ ±35cm －１ , wavelength 1500cm －１ ±35cm －１ , wavelength 1600cm －１ ±35cm －１ Among the ten infrared absorption spectra, some IR spectra are present and some are absent depending on the position in the thickness direction of the laminate. The sixth IR spectrum from the top shown in Figure 5 has a peak at a wavelength of 1150 cm －１ ±35cm －１ Also, the wavelength is 1500 cm －１ ±35cm －１ , wavelength 1600cm －１ ±35cm －１ From these results, it was confirmed that the laminate of Test Example 21 had a first resin layer, a second resin layer, and a resin diffusion layer formed between the first resin layer and the second resin layer and containing a resin component made of a third resin different from the first resin and the second resin.

[0170] As shown in FIG. 5, the wavelength of 1260 cm 2 originating from C═O in the IR spectrum －１ ±35cm －１, wavelength 1741cm －１ ±25cm －１ The peak of is present in all of the IR spectra shown in Fig. 5. From this, it was confirmed that the first resin contained in the first resin layer, the second resin contained in the second resin layer, and the third resin contained in the resin diffusion layer have, among the structural units derived from monomers, a structural unit derived from urethane as a common structural unit.

[0171] In addition, the wavelength of 1260 cm attributable to C═O in the IR spectrum shown in FIG. －１ ±35cm －１ , wavelength 1741cm －１ ±25cm －１ and a peak intensity of 1114 cm due to fluorene. －１ ±35cm －１ , wavelength 1500cm －１ ±35cm －１ , wavelength 1600cm －１ ±35cm －１ From the peak intensities of the first and second resins, it was confirmed that the proportion of structural units derived from urethane was low in the first resin (first resin layer), higher in the third resin (resin diffusion layer) than in the first resin, and higher in the second resin (second resin layer) than in the third resin.

[0172] 1...resin wiring board, 11...resin base material (first resin layer), 24...wiring pattern, 31...resin coating layer (second resin layer).

Claims

1. A resin wiring board comprising: a first resin layer containing a resin component made of a first resin; a second resin layer laminated on the first resin layer, containing a resin component made of a second resin, and having a lower Young's modulus than the first resin layer; a wiring pattern disposed between the first resin layer and the second resin layer, with a first surface formed in contact with the first resin layer and a second surface opposite to the first surface formed in contact with the second resin layer; and a resin diffusion layer disposed between the first resin layer and the second resin layer at least in a region not overlapping with the wiring pattern in a planar view, the resin diffusion layer containing a resin component made of a third resin, wherein the first resin, the second resin, and the third resin have common structural units in which some or all of the structural units derived from monomers are the same.

2. The resin wiring board described in claim 1, wherein the first resin, the second resin and the third resin each have a different proportion of the common structural unit contained in a structural unit derived from a monomer, and the proportion of the common structural unit of the third resin is a value between the proportion of the common structural unit of the first resin and the proportion of the common structural unit of the second resin, and changes continuously or stepwise in the thickness direction of the resin diffusion layer.

3. The resin wiring board according to claim 1, wherein the common structural unit includes one or both of a structural unit derived from a compound having a urethane bond and a polymerizable unsaturated bond and a structural unit derived from a compound having a fluorene skeleton.

4. The resin wiring board according to claim 1, wherein the wiring pattern is made of a conductive resin containing the common structural unit.

5. The resin wiring board according to claim 1, wherein the first resin contains a structural unit derived from a compound having a siloxane bond and a polymerizable unsaturated bond.

6. The resin wiring board according to claim 1, wherein the Young's modulus of said first resin layer is 3.5 times or more the Young's modulus of said second resin layer.

7. The Young's modulus of the second resin layer is 25 N / mm ２ The resin wiring board according to claim 1 , wherein:

8. The resin wiring board according to claim 1, wherein the first resin layer contains a filler.

9. A stretchable device comprising a resin wiring board according to any one of claims 1 to 8.

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