Resin composite laminate, method for producing resin composite laminate, and stretchable device

Abstract

To provide a resin composite laminate in which an urethane resin layer and a polyimide resin layer are hardly peeled, and a fold is hardly generated even being folded, and a production method thereof.SOLUTION: There is provided a resin composite laminate which has: an urethane resin layer comprising, an urethane bond and a siloxane bond, having a weight average molecular weight of 52200-260000 and being soluble in a solvent; and a polyimide resin layer having a polyimide resin having an imide bond. Peel strength between the urethane resin layer and the polyimide resin layer is 1.6 N or greater per 10 mm of a width, in the resin composite laminate.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composite laminate, a method for producing a resin composite laminate, and a stretchable device. [Background technology]

[0002] Wearable devices have been attracting attention in recent years. Wearable devices measure and monitor the characteristics of specific parts of the human body. Wearable devices are used by being embedded in clothing or attached directly to the skin. Wearable devices are expected to be applied in a wide range of fields, including sports science and healthcare.

[0003] Wearable devices are desirably stretchable devices that can follow human movements and provide a stress-free fit. Wearable devices are also equipped with electrodes, wiring, electronic components, sensors, etc. Therefore, in wearable devices, the sheet layers on which the electrodes, wiring, electronic components, sensors, etc. are installed, and the elements used for the sealing layers that seal these, must be sufficiently heat-resistant.

[0004] Resins with good heat resistance include epoxy resins, polyimide resins, and polyamide resins, but these resins often lack flexibility. Resins with good flexibility include urethane resin, silicone resin, and acrylic resin. However, all of the urethane, silicone, and acrylic resins that are classified as having good elasticity have insufficient heat resistance to be used as materials for the body of a wearable device equipped with electronic components.

[0005] Patent Document 1 describes a polyimide cover substrate including a polyimide film and an element protection layer formed from a urethane acrylate compound on at least one surface of the polyimide film. Patent Document 2 describes a urethane-modified polyimide resin solution containing a urethane-modified polyimide resin (A) containing an amide-imide unit (i) composed of a trimellitic acid derivative and an aromatic diisocyanate component, and a urethane unit (ii) composed of tricyclodecane dimethanol and an aromatic diisocyanate component, and one or more organic solvents (B) selected from the group consisting of cyclohexanone and cyclopentanone.

[0006] Patent Document 3 describes an electronic component mounting substrate including a substrate and electronic components mounted on the substrate, a resin layer covering the substrate and at least a portion of the electronic components, and a sealing film covering the substrate and at least a portion of the electronic components via the resin layer. Patent Document 3 also describes that the resin layer is mainly made of a solvent-soluble resin, and the sealing film is mainly made of a resin material, and has an elongation at the softening point determined in accordance with JIS K6251 of 150% or more and 3500% or less. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 2016-521216 [Patent Document 2] Patent No. 6070911 [Patent Document 3] Japanese Patent Application Publication No. 2019-134095 Summary of the Invention [Problem to be solved by the invention]

[0008] A stretchable device requires a material with sufficient stretchability and heat resistance. One possible material is a resin composite laminate made by laminating a urethane resin layer containing a urethane resin with good stretchability and a polyimide resin layer containing a polyimide resin with good heat resistance. However, such a resin composite laminate has a problem in that the urethane resin layer and the polyimide resin layer are easily peeled off when stretched, and also has a tendency to crease when bent, making it difficult to use as a base for a stretchable device.

[0009] The present invention has been made in consideration of the above circumstances, and aims to provide a resin composite laminate in which the urethane resin layer and the polyimide resin layer are not easily peeled off and which is not easily creased when bent, and a method for producing the same. Another object of the present invention is to provide a stretchable device having a base body that includes the resin composite laminate of the present invention, is resistant to creases when bent, and has sufficient stretchability and heat resistance. [Means for solving the problem]

[0010] The present inventors have conducted extensive research to solve the above problems. As a result, the present inventors discovered that a resin composite laminate having a urethane resin layer containing a specific urethane resin soluble in a solvent and a polyimide resin layer containing a polyimide resin, in which the peel strength between the urethane resin layer and the polyimide resin layer is 1.6 N or more per 10 mm width, was sufficient, and thus the present invention was conceived. That is, the present invention relates to the following items.

[0011] [1] A urethane resin layer containing a urethane resin having a urethane bond and a siloxane bond, a weight average molecular weight of 52,200 to 260,000, and being soluble in a solvent; a polyimide resin layer containing a polyimide resin having an imide bond; A resin composite laminate, wherein the peel strength between the urethane resin layer and the polyimide resin layer is 1.6 N or more per 10 mm width.

[0012] [2] The resin composite laminate according to [1], wherein the urethane resin has a group represented by the following general formula (11), (21), or (31), a urethane bond, and a siloxane bond:

[0013] [ka] (In the formula, 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, or a methoxycarbonyl group, and the two or more substituents may be the same or different. 2 is an alkyl group. Z 3 is an aryl group. 4 is a hydrogen atom or a halogen atom. A bond marked with a symbol * is formed between the bond destination of the group represented by general formula (11), (21), or (31).

[0014] [3] The resin composite laminate according to [1] or [2], wherein the polyimide resin is soluble in the solvent. [4] The resin composite laminate according to any one of [1] to [3], wherein the polyimide resin is any one selected from the group consisting of silicone-modified polyimide resins, polyamide-imide resins, aromatic polyimide resins, epoxy-modified polyimides, and urethane-modified polyimides.

[0015] [5] The resin composite laminate according to any one of [1] to [4], wherein the polyimide resin layer has a thickness of 10 μm or less. [6] The resin composite laminate according to any one of [1] to [5], which has a tensile strength per 10 mm width of 4.35 N or less.

[0016] [7] A method for producing the resin composite laminate according to any one of [1] to [6], a solidified layer forming step of forming a solidified layer made of any one selected from a solidified product obtained by solidifying a polyimide resin composition containing the polyimide resin by drying, a semi-cured product obtained by semi-curing the polyimide resin, and a partially cured product obtained by only partially curing the polyimide resin; a urethane resin composition containing the urethane resin and the solvent is applied to the solidified layer, followed by drying and solidifying the composition to form the urethane resin layer and the polyimide resin layer, and an intermediate layer forming step of forming an intermediate layer in contact with the urethane resin layer and the polyimide resin layer.

[0017] [8] The polyimide resin is soluble in the solvent, The method for producing a resin composite laminate according to [7], wherein in the intermediate layer forming step, the urethane resin composition is applied to dissolve the polyimide resin contained in the solidified layer in the solvent. [9] A stretchable device having an element comprising the resin composite laminate according to any one of [1] to [6]. [Effects of the Invention]

[0018] The resin composite laminate of the present invention comprises a urethane resin layer containing a solvent-soluble urethane resin having a urethane bond and a siloxane bond and a weight-average molecular weight of 52,200 to 260,000, and a polyimide resin layer containing a polyimide resin having an imide bond, and the peel strength between the urethane resin layer and the polyimide resin layer is 1.6 N or more per 10 mm width. Therefore, the resin composite laminate of the present invention has good adhesion between the urethane resin layer and the polyimide resin layer, and is not easily peeled. Moreover, the resin composite laminate of the present invention is not easily creased when folded.

[0019] Furthermore, the resin composite laminate of the present invention has a urethane resin layer containing a urethane resin having a urethane bond and a siloxane bond and a weight-average molecular weight of 52,200 to 260,000, and therefore has good stretchability. Furthermore, the resin composite laminate of the present invention has a polyimide resin layer containing a polyimide resin having an imide bond, and therefore has good heat resistance. For these reasons, the resin composite laminate of the present invention is suitable as a base for a stretchable device.

[0020] In the method for producing a resin composite laminate of the present invention, a polyimide resin composition containing a polyimide resin is dried to form a solidified layer selected from the group consisting of a solidified product, a semi-cured product, and a partially cured product, and a urethane resin composition containing a urethane resin and a solvent is applied to the solidified layer and dried to solidify it. Therefore, the method for producing a resin composite laminate of the present invention can produce a resin composite laminate having a urethane resin layer, a polyimide resin layer, and an intermediate layer formed in contact with the urethane resin layer and the polyimide resin layer, where the urethane resin penetrates into the polyimide resin layer and is integrated with the urethane resin layer and the polyimide resin layer.

[0021] The stretchable device of the present invention has an element body including the resin composite laminate of the present invention. Therefore, the stretchable device of the present invention is resistant to creases even when bent, and has sufficient stretchability and heat resistance. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a cross-sectional schematic view showing an example of a resin composite laminate according to one embodiment of the present invention. [Figure 2] FIG. 1 is a schematic diagram illustrating an example of a stretchable device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] In order to solve the above problems, the present inventors have conducted extensive research as described below. The present inventors have focused on and investigated the cause of delamination between a urethane resin layer and a polyimide resin layer when a resin composite laminate formed by laminating a urethane resin layer and a polyimide resin layer is stretched and contracted. The cause of delamination in a resin composite laminate is the large difference in tensile stress between the urethane resin layer and the polyimide resin layer due to the difference in stretchability between the urethane resin layer and the polyimide resin layer.

[0024] Therefore, one possible method for making the resin composite laminate less susceptible to peeling is to improve the elasticity of the polyimide resin layer and reduce the difference in elasticity between the urethane resin layer and the polyimide resin layer. However, even conventional polyimide resins with good elasticity have very little elasticity compared to urethane resins. In other words, there has not been a polyimide resin with a small difference in elasticity compared to urethane resins.

[0025] Another possible method for preventing peeling of a resin composite laminate is to improve the adhesion between the urethane resin layer and the polyimide resin layer. Typically, a polyimide resin layer is produced by applying a resin composition containing a polyimide resin to a substrate and thermally curing the composition. However, when the polyimide resin is thermally cured on the urethane resin layer to produce a resin composite laminate, the urethane resin layer deteriorates. For this reason, when producing a resin composite laminate comprising a urethane resin layer and a polyimide resin layer, a method is used in which a polyimide resin layer is formed on a peelable substrate and the polyimide resin layer peeled from the substrate is attached to the urethane resin layer. However, the method of attaching a polyimide resin layer to a urethane resin layer does not provide sufficient adhesion between the urethane resin layer and the polyimide resin layer.

[0026] Another possible method for preventing delamination of the resin composite laminate is to provide a resin intermediate layer containing both urethane resin and polyimide resin between the urethane resin layer and the polyimide resin layer to mitigate the difference in tensile stress between the urethane resin layer and the polyimide resin layer during expansion and contraction. However, mixing the urethane resin and polyimide resin before curing hinders the curing reaction, making it difficult to form a resin intermediate layer.

[0027] Therefore, the present inventors have focused on a resin composition containing a urethane resin dissolved in a solvent and have conducted extensive research as described below. That is, the present inventors have found that a urethane resin layer having sufficient elasticity can be obtained by applying a urethane resin composition containing a solvent-soluble urethane resin having a urethane bond and a siloxane bond and a weight average molecular weight (Mw) of 52,200 to 260,000 onto a substrate and drying and solidifying it.

[0028] The inventors then produced a resin composite laminate by applying the above-mentioned urethane resin composition to a polyimide resin layer prepared by thermal curing on a substrate instead of using a substrate, and then solidifying the composition. However, the resulting resin composite laminate failed to suppress peeling between the urethane resin layer and the polyimide resin layer. Specifically, the peel strength between the urethane resin layer and the polyimide resin layer was less than 1.6 N. Furthermore, the resin composite laminate was prone to creases when bent.

[0029] This is presumably because, even when the urethane resin composition is applied to a polyimide resin layer prepared by thermal curing on a substrate, the urethane resin does not penetrate into the polyimide resin layer, and as a result, an intermediate layer containing both the urethane resin and the polyimide resin is not formed between the urethane resin layer and the polyimide resin layer, resulting in insufficient adhesion between the urethane resin layer and the polyimide resin layer.

[0030] Therefore, the present inventors focused on the condition of the surface to be coated with the urethane resin composition and conducted further extensive research. As a result, they discovered that it is sufficient to apply the urethane resin composition to a solidified layer consisting of one of a solidified product obtained by drying and solidifying a resin composition containing a polyimide resin, a semi-cured product obtained by semi-curing, and a partially cured product obtained by only partially curing, and then dry and solidify the urethane resin composition. The resin composite laminate obtained in this manner had a peel strength of 1.6 N or more between the urethane resin layer and the polyimide resin layer, and exhibited good adhesion between the urethane resin layer and the polyimide resin layer. This is presumably due to the urethane resin penetrating into the polyimide resin layer, forming an intermediate layer integrated with the urethane resin layer and the polyimide resin layer, in contact with the urethane resin layer and the polyimide resin layer.

[0031] Furthermore, the inventors have confirmed that the resin composite laminate obtained in this manner is resistant to peeling between the urethane resin layer and the polyimide resin layer, is resistant to creases when bent, and has sufficient stretchability and heat resistance, and have conceived the present invention.

[0032] Hereinafter, the resin composite laminate, the method for producing the resin composite laminate, and the stretchable device of the present invention will be described in detail with reference to the drawings. In addition, the drawings used in the following explanation may show enlarged essential parts for the sake of convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may not necessarily be the same as in reality.

[0033] [Resin composite laminate] Fig. 1 is a cross-sectional schematic diagram showing an example of a resin composite laminate according to one embodiment of the present invention. As shown in Fig. 1, the resin composite laminate 10 of this embodiment has a urethane resin layer 21, a polyimide resin layer 22, and an intermediate layer 23 formed between the urethane resin layer 21 and the polyimide resin layer 22. The resin composite laminate 10 has a peel strength between the urethane resin layer and the polyimide resin layer of 1.6 N or more per 10 mm width. The resin composite laminate 10 is bendable and stretchable.

[0034] "Urethane resin layer" The urethane resin layer 21 contains a urethane resin having a urethane bond and a siloxane bond. The urethane resin preferably has both a urethane bond and a siloxane bond in one molecule. The urethane resin has high flexibility due to the urethane bond. Furthermore, the urethane resin has a siloxane bond, which inhibits hydrolysis of the urethane bond.

[0035] The urethane resin contained in the urethane resin layer 21 is soluble in a solvent. The urethane resin layer 21 is formed by applying and solidifying a urethane resin composition containing a urethane resin and a solvent.

[0036] The urethane resin is preferably soluble in solvents such as N-methyl-2-pyrrolidone (NMP), γ-butyrolactone (GBL), N,N-dimethylacetamide (DMAc), methyl ethyl ketone (MEK), N,N-dimethylformamide (DMF), diethylene glycol monobutyl ether (BCA), diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, acetone, ethanol, methanol, ethyl lactate, butyl lactate, toluene, isopropyl alcohol, isobutyl alcohol, ethyl acetate, and butyl acetate. The urethane resin is preferably soluble in at least one solvent selected from N-methyl-2-pyrrolidone (NMP), γ-butyrolactone (GBL), and N,N-dimethylacetamide (DMAc), which are solvents that dissolve polyimide resins.

[0037] The urethane resin has a weight-average molecular weight (Mw) of 52,200 to 260,000, preferably 61,000 to 250,000. Since the weight-average molecular weight (Mw) of the urethane resin contained in the urethane resin layer 21 is 52,200 or more, the urethane resin layer 21 has sufficient strength. Furthermore, since the weight-average molecular weight (Mw) of the urethane resin is 260,000 or less, the urethane resin layer 21 has sufficient elasticity. Furthermore, since the weight-average molecular weight (Mw) of the urethane resin is 260,000 or less, it can be dissolved in a solvent.

[0038] In this specification, unless otherwise specified, the term "weight average molecular weight" refers to a polystyrene equivalent value measured by gel permeation chromatography (GPC).

[0039] The urethane resin contained in the urethane resin layer 21 preferably has a group represented by the following general formula (11), (21) or (31), a urethane bond, and a siloxane bond.

[0040] [ka] (In the formula, 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, or a methoxycarbonyl group, and the two or more substituents may be the same or different. 2 is an alkyl group. Z 3 is an aryl group. 4 is a hydrogen atom or a halogen atom. A bond marked with a symbol * is formed between the bond destination of the group represented by general formula (11), (21), or (31).

[0041] The urethane resin contained in the urethane resin layer 21 is obtained by carrying out a polymerization reaction using a resin having a urethane bond and a polymerizable unsaturated bond, and a resin having a siloxane bond and a polymerizable unsaturated bond, and further using a RAFT agent for carrying out reversible addition-fragmentation chain transfer polymerization (sometimes abbreviated as "RAFT polymerization" in this specification), from which a group represented by general formula (11), (21), or (31) is derived. By performing RAFT polymerization, gelation of the polymerizing resin during the process of forming a crosslinked structure can be avoided, and a resin component with a desired degree of polymerization and crosslinked state can be obtained. That is, the urethane resin contained in the urethane resin layer 21 has small variations in degree of polymerization and crosslinked state.

[0042] The resin having a urethane bond and a polymerizable unsaturated bond used in producing the urethane resin is an oligomer (sometimes referred to as "resin (a)" in this embodiment). The resin having a siloxane bond and a polymerizable unsaturated bond used in the production of the urethane resin is an oligomer (sometimes referred to as "resin (b)" in this embodiment). The urethane resin is a polymer produced by polymerizing the resin (a) and the resin (b) at their polymerizable unsaturated bonds.

[0043] The resin (a) is not particularly limited as long as it has a urethane bond and a polymerizable unsaturated bond. Examples of the resin (a) include those having a urethane bond and a (meth)acryloyl group as a group having a polymerizable unsaturated bond. Specifically, examples of the resin (a) include urethane (meth)acrylate.

[0044] In this specification, the term "(meth)acrylate" is a concept that encompasses both "acrylate" and "methacrylate." The same applies to terms similar to (meth)acrylate. For example, the term "(meth)acryloyl group" is a concept that encompasses both "acryloyl group" and "methacryloyl group."

[0045] The weight average molecular weight (Mw) of the resin (a) is preferably 3000 to 50000, and more preferably 15000 to 50000. By using the resin (a) having such a weight average molecular weight, a urethane resin with better properties can be obtained.

[0046] Resin (b) is not particularly limited as long as it has a siloxane bond and a polymerizable unsaturated bond. Examples of resin (b) include various known silicone resins having a (meth)acryloyl group as the group having a polymerizable unsaturated bond. Specific examples of resin (b) include modified polydialkylsiloxanes in which a (meth)acryloyl group is bonded to one or both ends of a polydialkylsiloxane such as polydimethylsiloxane.

[0047] The number average molecular weight (Mn) of the resin (b) is preferably 400 to 10000, and more preferably 5000 to 10000. By using the resin (b) having such a number average molecular weight, a urethane resin with better properties can be obtained.

[0048] In general formula (11), Z 1 is an alkyl group. Z 1 The alkyl group in may be linear, branched, or cyclic, is preferably linear or branched, and is more preferably linear.

[0049] Z 1The number of carbon atoms in the linear or branched alkyl group in the formula (I) is preferably 1 to 12. Examples of such alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, 1-methylbutyl, 2-methylbutyl, hexyl, heptyl, n-octyl, isooctyl, 2-ethylhexyl, nonyl, decyl, undecyl, and dodecyl groups. 1 The linear or branched alkyl group may have, for example, 1 to 8 carbon atoms, 1 to 5 carbon atoms, or 1 to 3 carbon atoms.

[0050] Z 1 The cyclic alkyl group in may be either monocyclic or polycyclic, and is preferably monocyclic. Z 1 The number of carbon atoms in the cyclic alkyl group is preferably 3 to 6. Examples of such an alkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.

[0051] Z 1 In the formula (I), one or more hydrogen atoms in the alkyl group may or may not be substituted with a cyano group (-CN), a carboxy group (-C(=O)-OH), or a methoxycarbonyl group (-C(=O)-OCH3). Z 1 When two or more hydrogen atoms in the alkyl group in the formula (I) are substituted with a cyano group, a carboxy group, or a methoxycarbonyl group, the two or more substituents may be the same or different. When hydrogen atoms are substituted with a cyano group, a carboxy group, or a methoxycarbonyl group, all hydrogen atoms in the alkyl group may be substituted, but it is preferable that unsubstituted hydrogen atoms exist. The number of substituted hydrogen atoms in the alkyl group is preferably 1 or 2, and more preferably 1.

[0052] Z1 In the formula (I), examples of the alkyl group in which a hydrogen atom is substituted with a cyano group, a carboxy group, or a methoxycarbonyl group include a 1-carboxyethyl group (-CH(CH3)COOH), a 2-carboxyethyl group (-CH2CH2COOH), a 4-carboxy-2-cyano-sec-butyl group (-C(CH3)(CN)CH2CH2COOH), a 2-cyano-4-methoxycarbonyl-sec-butyl group (-C(CH3)(CN)CH2CH2COOCH3), a 1-cyano-1-methylethyl group (-C(CH3)(CN)CH3), a cyanomethyl group (-CH2CN), a 1-cyano-1-methyl-n-propyl group (-C(CH3)(CN)CH2CH3), and a 2-cyano-2-propyl group (-C(CH3)(CN)CH3). A 2-carboxyethyl group is preferred.

[0053] Z 1 is preferably a dodecyl group (n-dodecyl group) or a 2-carboxyethyl group.

[0054] In general formula (21), Z 2 is an alkyl group. Z 2 The alkyl group in 1 Examples of the alkyl group include the same as those in the alkyl group. Z 2 The alkyl group in Z is preferably linear or branched, and more preferably linear. 2 The number of carbon atoms in the linear or branched alkyl group in Z may be, for example, 1 to 12, 1 to 8, 1 to 5, or 1 to 3. 2 is preferably a methyl group.

[0055] In general formula (21), Z 3 is an aryl group. Z 3 The aryl group in may be either monocyclic or polycyclic, and is preferably monocyclic. Z 3The number of carbon atoms in the aryl group in Z is preferably 6 to 12. Examples of such aryl groups include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, an o-tolyl group, a m-tolyl group, a p-tolyl group, and a xylyl group (dimethylphenyl group). 3 is preferably a phenyl group.

[0056] In general formula (31), R 4 is a hydrogen atom or a halogen atom. R 4 Examples of the halogen atom in R include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a chlorine atom is preferred. 4 is preferably a hydrogen atom or a chlorine atom.

[0057] In general formula (11), (21), or (31), the bond marked with * is formed between the group represented by general formula (11), (21), or (31) and the terminal portion of the polymer of resin (a) or resin (b).

[0058] Examples of RAFT agents from which the group represented by general formula (11) is derived include compounds represented by the following general formula (1) (sometimes abbreviated as "RAFT agent (1)" in this specification).

[0059] [ka] (In the formula, R 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, or a methoxycarbonyl group, and the two or more substituents may be the same or different. 1 is Z in the general formula (11) 1 is the same as

[0060] R in general formula (1) 1In the above, examples of the alkyl group in which one or more hydrogen atoms may be substituted by a cyano group, a carboxy group or a methoxycarbonyl group include the above-mentioned Z 1 and R 1 The substitution of hydrogen atoms in Z 1 The substitution of hydrogen atoms is the same as in the above.

[0061] R 1 is preferably a 1-carboxyethyl group, a 4-carboxy-2-cyano-sec-butyl group, a 1-cyano-1-methylethyl group, a 2-cyano-4-methoxycarbonyl-sec-butyl group, a cyanomethyl group, or a 2-cyano-2-propyl group. Z in the general formula (1) 1 represents Z in the general formula (11). 1 is the same as

[0062] When the RAFT agent (1) is used, a polymerizable compound having the general formula R 1 A group represented by the following formula is bonded to the ring.

[0063] Examples of RAFT agents from which the group represented by general formula (21) is derived include compounds represented by the following general formula (2) (sometimes abbreviated as "RAFT agent (2)" in this specification).

[0064] [ka] (In the formula, R 2 is an alkyl group, and one or more hydrogen atoms in the alkyl group may be substituted with a cyano group, a carboxy group, or a methoxycarbonyl group, and the two or more substituents may be the same or different. 2 and Z 3 represents Z in the general formula (21). 2 and Z 3is the same as

[0065] R in general formula (2) 2 In the above, examples of the alkyl group in which one or more hydrogen atoms may be substituted by a cyano group, a carboxy group or a methoxycarbonyl group include the above-mentioned Z 1 and R 2 The substitution of hydrogen atoms in Z 1 The substitution of hydrogen atoms is the same as in the above. R 2 is preferably a cyanomethyl group. Z in the general formula (2) 2 and Z 3 represents Z in the general formula (21). 2 and Z 3 is the same as

[0066] When the RAFT agent (2) is used, a polymerizable group represented by the general formula R 2 A group represented by the following formula is bonded to the ring.

[0067] Examples of the RAFT agent from which the group represented by general formula (31) is derived include a compound represented by the following general formula (3) (sometimes abbreviated as "RAFT agent (3)" in this specification).

[0068] [ka] (In the formula, R 3 R is an alkyl group, and one or more hydrogen atoms in the alkyl group may be substituted with a cyano group, a carboxy group, or a methoxycarbonyl group, and the two or more substituents may be the same or different. 4 represents Z in the general formula (31). 4 is the same as

[0069] R in general formula (3) 3 In the above, examples of the alkyl group in which one or more hydrogen atoms may be substituted by a cyano group, a carboxy group or a methoxycarbonyl group include the above-mentioned Z 1 and R 3 The substitution of hydrogen atoms in Z 1 The substitution of hydrogen atoms is the same as in the above. R 3 is preferably a cyanomethyl group or a 1-cyano-1-methyl-n-propyl group. R in the general formula (3) 4 is R in the general formula (31). 4 is the same as

[0070] When the RAFT agent (3) is used, a polymer of the resin (a) and the resin (b) is polymerized to a terminal portion to which the group represented by the general formula (31) is not bonded, and a group represented by the general formula R 3 A group represented by the following formula is bonded to the ring.

[0071] As raw materials for the urethane resin, in addition to resin (a) and resin (b), other polymerizable components not falling under these may also be used. Examples of the other polymerizable component include a monomer or oligomer having a polymerizable unsaturated bond. Specific examples of the other polymerizable component include alkyl (meth)acrylates such as 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.

[0072] In addition to the above-mentioned components, one or more other non-polymerizable components may be used as raw materials for the urethane resin, if necessary. The other non-polymerizable components can be selected arbitrarily depending on the purpose, and are preferably non-conductive components.

[0073] The urethane resin contained in the urethane resin layer 21 can be produced, for example, by the following method. The urethane resin can be produced by a method in which a raw material mixture is prepared by blending resin (a), resin (b), a RAFT agent (i.e., RAFT agent (1), RAFT agent (2), or RAFT agent (3)), a polymerization initiator (sometimes referred to herein as "polymerization initiator (c)"), a solvent, other polymerizable components that are used as needed, and other non-polymerizable components that are used as needed, and a polymerization reaction is carried out in the raw material mixture to produce the urethane resin.

[0074] The raw material mixture may contain only one type of resin (a), or two or more types. In the raw material mixture, the content of resin (a) in the components other than the solvent of the raw material mixture (in other words, in the "solid content") is preferably 60 to 99 mass %, more preferably 80 to 98 mass %. When the content is 60 mass % or more, a urethane resin with good flexibility is obtained. When the content is 99 mass % or less, a urethane resin with excellent strength is obtained.

[0075] The raw material mixture may contain only one type of resin (b), or two or more types. In the raw material mixture, the content of resin (b) is preferably 0.2 to 25 parts by mass, more preferably 0.2 to 20 parts by mass, and even more preferably 0.2 to 17 parts by mass, per 100 parts by mass of resin (a). When the content is 0.2 parts by mass or more, the water repellency of the urethane resin is more clearly improved. When the content is 25 parts by mass or less, excessive use of resin (b) is avoided, and the urethane resin layer 21 is prevented from becoming unnecessarily hard or from becoming less uniform.

[0076] The raw material mixture may contain only one type of RAFT agent (RAFT agents (1) to (3)), or two or more types, and usually only one type is sufficient. In the raw material mixture, the content of the RAFT agent is preferably 0.03 to 5 parts by mass, more preferably 0.03 to 4.5 parts by mass, and even more preferably 0.03 to 4 parts by mass, per 100 parts by mass of the resin (a). When the content is 0.03 part by mass or more, the effect of using the RAFT agent is more pronounced. When the content is 5 parts by mass or less, excessive use of the RAFT agent can be avoided.

[0077] The polymerization initiator (c) may be any known one and is not particularly limited. Examples of the polymerization initiator (c) include dimethyl-2,2'-azobis(2-methylpropionate) and azobisisobutyronitrile. The raw material mixture may contain only one type of polymerization initiator (c), or two or more types, and usually only one type is sufficient.

[0078] In the raw material mixture, the content of the polymerization initiator (c) is preferably 0.5 to 5 parts by mass, more preferably 0.7 to 4 parts by mass, and even more preferably 0.9 to 3 parts by mass, per 100 parts by mass of the resin (a). When the content is 0.5 parts by mass or more, the polymerization reaction proceeds more smoothly. When the content is 5 parts by mass or less, excessive use of the polymerization initiator (c) can be avoided.

[0079] The solvent is not particularly limited as long as it does not exhibit reactivity with the above-mentioned components used in preparing the raw material mixture and the polymerization reaction product, but it is preferable to use a solvent that has good solubility for the components. Examples of the solvent include methyl ethyl ketone (MEK), diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, butyl acetate, ethyl acetate, ethyl lactate, butyl lactate, etc. The raw material mixture may contain only one type of solvent, or two or more types of solvents. When the reaction liquid obtained after the polymerization reaction is used as it is as a urethane resin composition when forming the urethane resin layer 21, it is preferable to use methyl ethyl ketone (MEK), diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, butyl acetate, or butyl lactate as the solvent.

[0080] The amount of solvent used is preferably such that the total content of components other than the solvent in the raw material mixture is 5 to 30 mass %, more preferably 10 to 25 mass %, relative to the total amount of the raw material mixture. By using the solvent in this range, the resin component (I) with better properties can be obtained more smoothly.

[0081] The raw material mixture may contain only one type of other polymerizable component, or two or more types. When using the other polymerizable component, the content of the other polymerizable component in the raw material mixture is preferably 5 to 55 parts by mass, more preferably 10 to 50 parts by mass, and even more preferably 15 to 45 parts by mass, per 100 parts by mass of the resin (a). When the content is 5 parts by mass or more, the effect of using the other polymerizable component is more pronounced. When the content is 55 parts by mass or less, the elasticity of the urethane resin is further improved.

[0082] In the raw material mixture, the total content of resin (a), resin (b), RAFT agent, polymerization initiator (c), and other polymerizable components, if used, is preferably 90 to 100 parts by mass, more preferably 95 to 100 parts by mass, and may be, for example, 97 to 100 parts by mass or 99 to 100 parts by mass, relative to 100 parts by mass of the total content of the raw material mixture other than the solvent. When the content is 90 parts by mass or more, the effects of the present invention are more pronounced.

[0083] The polymerization reaction for synthesizing the urethane resin is preferably carried out in an atmosphere of an inert gas such as nitrogen gas, helium gas, or argon gas. The temperature at which the polymerization reaction is carried out (reaction temperature) is preferably 70 to 110°C, and more preferably 80 to 100°C. The polymerization reaction time (reaction time) may be adjusted appropriately depending on the types of raw materials used and the reaction temperature, and can be set to, for example, 5 to 240 minutes.

[0084] In this embodiment, the polymerization reaction between resin (a) and resin (b) is carried out using RAFT agent (1), (2), or (3), allowing the polymerization reaction to proceed stably. In other words, a urethane resin can be synthesized stably so that the composition, molecular weight distribution, structure, and other properties fall within certain ranges. In particular, the reaction rate during the polymerization reaction can be appropriately controlled, which prevents the reaction from proceeding rapidly, causing a sudden increase in the viscosity of the reaction solution and resulting in gelation during the process of forming a crosslinked structure. Therefore, in this embodiment, a urethane resin with the desired degree of polymerization and crosslinked state can be stably obtained.

[0085] In addition to RAFT polymerization using a RAFT agent, other known methods of radical polymerization include atom transfer radical polymerization (ATRP) and nitroxide-mediated polymerization (NMP). However, ATRP has the drawback of requiring a high concentration of a catalyst containing a transition metal to carry out the polymerization reaction. Furthermore, NMP has the drawback of being difficult to control the polymerization reaction and having low versatility. Due to these drawbacks, these methods are not suitable for producing the urethane resin of this embodiment. In contrast, in the present embodiment, by selecting RAFT polymerization using RAFT agent (1), (2), or (3), a urethane resin having the desired properties can be produced stably and with high versatility.

[0086] In this embodiment, the urethane resin composition used to form the urethane resin layer 21 contains a urethane resin and a solvent. In this embodiment, the reaction liquid obtained after the polymerization reaction to synthesize the urethane resin may be used as is as the urethane resin composition when forming the urethane resin layer 21, or the reaction liquid obtained may be subjected to a known post-treatment and then used as the urethane resin composition. Alternatively, the reaction liquid may be purified by a known purification method to extract only the urethane resin, which may then be mixed with a solvent and used as the urethane resin composition.

[0087] The urethane resin layer 21 may contain other resins besides urethane resin as needed. As the other resins, it is preferable to use those that have good elasticity and are soluble in solvents, such as silicone resin, acrylic resin, methacrylic resin, and fluorine-based resin.

[0088] The thickness of the urethane resin layer 21 is preferably 10 to 1000 μm, and more preferably 20 to 300 μm. When the thickness of the urethane resin layer 21 is 10 μm or more, the resin composite laminate 10 has sufficient strength and good stretchability. When the thickness of the urethane resin layer 21 is 1000 μm or less, the urethane resin layer 21 can be easily formed by applying a urethane resin composition and drying and solidifying it, and the resin composite laminate 10 has sufficient stretchability.

[0089] "Polyimide resin layer" The polyimide resin layer 22 contains a polyimide resin having an imide bond. The polyimide resin has good heat resistance due to the imide bond. The polyimide resin layer 22 is formed by forming a urethane resin layer 21 on a solidified layer consisting of one of a polyimide resin composition containing a polyimide resin, a solidified product obtained by drying the polyimide resin composition, a semi-cured product obtained by semi-curing the polyimide resin, and a partially cured product obtained by only partially curing the polyimide resin, and then curing the resulting layer as necessary.

[0090] The polyimide resin contained in the polyimide resin layer 22 is preferably soluble in a solvent that dissolves the urethane resin contained in the urethane resin layer 21. In this case, the polyimide resin layer 22 can be formed, for example, by applying a polyimide resin composition containing the polyimide resin to a substrate and solidifying it by drying. Therefore, there is no need to thermally cure the polyimide resin, and the polyimide resin layer 22 can be formed without causing damage to the substrate that would otherwise be caused by thermally curing the polyimide resin. Furthermore, since the polyimide resin layer 22 can be formed by the above method, a thin polyimide resin layer 22 can be easily formed. As a result, the adhesion between the urethane resin layer and the polyimide resin layer is improved, resulting in a resin composite laminate 10 that is less likely to crease or peel even when bent.

[0091] Furthermore, when the polyimide resin is soluble in a solvent that dissolves the urethane resin contained in the urethane resin layer 21, the following effect can be achieved. Specifically, by applying a urethane resin composition containing a urethane resin dissolved in a solvent onto a solidified layer of a polyimide resin composition containing a polyimide resin, both the urethane resin and the polyimide resin can be dissolved and solidified in the solvent. As a result, the urethane resin diffuses into the solidified layer, and an intermediate layer 23 containing both the urethane resin and the polyimide resin and integrated with the urethane resin layer 21 and the polyimide resin layer 22 is easily and reliably formed between the urethane resin layer 21 and the polyimide resin layer 22. This results in a resin composite laminate 10 that is even more resistant to peeling and creases when bent. Furthermore, when the polyimide resin is soluble in a solvent in which the urethane resin contained in the urethane resin layer 21 is soluble, a polyimide resin composition that does not contain a curing agent can be used.

[0092] The polyimide resin is preferably any one selected from the group consisting of aromatic polyimide resin, silicone-modified polyimide resin, polyamide-imide resin, epoxy-modified polyimide resin, and urethane-modified polyimide resin. These polyimide resins have good heat resistance and stretchability, and therefore the resin composite laminate 10 is more resistant to peeling and has excellent heat resistance. As the polyimide resin, it is more preferable to use any one selected from aromatic polyimide resins, silicone-modified polyimide resins, and polyamide-imide resins.

[0093] Examples of aromatic polyimide resins include aromatic polyimide resins having an aliphatic hydrocarbon chain or an alicyclic skeleton. Aromatic polyimide resins have a high conjugated molecular structure, making them particularly excellent in heat resistance among polyimide resins. Furthermore, aromatic polyimide resins can easily bond with other compounds. Therefore, aromatic polyimide resins may be used that have functional groups introduced therein to impart functions other than heat resistance, as needed.

[0094] As the silicone-modified polyimide resin, for example, one having a skeleton formed by polymerizing BPDA (3,3',4,4'-biphenyltetracarboxylic dianhydride) and having a silicone structure introduced into the skeleton can be used. Specifically, the silicone-modified polyimide resin may be a polyimide resin represented by the following general formula (5).

[0095] [ka] (In the formula, R is an aromatic hydrocarbon group, R' is a repeating unit consisting of -Si-O-Si- or -C-Si-O-Si-C-, and the number of repeating units is 1 or more, and n is 5 to 400.)

[0096] The polyimide resin represented by formula (5) has hydrophobicity and good mechanical properties due to the presence of siloxane bonds. When the polyimide resin is a silicone-modified polyimide resin represented by formula (5), the resin composite laminate 10 has even better adhesion between the urethane resin layer 21 and the polyimide resin layer 22 and excellent tensile properties. In the polyimide resin represented by formula (5), the number of repeating units R' is 1 or more. The upper limit of the number of repeating units R' may be set within a range that ensures the heat resistance required for the polyimide resin layer 22, and can be appropriately determined depending on the application of the resin composite laminate 10, etc.

[0097] Examples of polyamideimide resins include polyamideimides obtained by reacting a diisocyanate compound such as 4,4'-diphenylmethane diisocyanate with a tribasic acid anhydride such as trimellitic anhydride.

[0098] The polyimide resin layer 22 may contain other resins besides polyimide resin as needed. The other resins to be used are preferably those that have good heat resistance and are soluble in solvents, such as polyamide resin, epoxy resin, and silicone resin.

[0099] The thickness of the polyimide resin layer 22 is preferably 1 to 10 μm, and more preferably 3 to 10 μm. When the thickness of the polyimide resin layer 22 is 1 μm or more, the resin composite laminate 10 has better heat resistance. When the thickness of the polyimide resin layer 22 is 10 μm or less, the adhesion between the urethane resin layer 21 and the polyimide resin layer 22 is further improved, resulting in a resin composite laminate 10 that is less likely to crease when bent. Furthermore, when the thickness of the polyimide resin layer 22 is 10 μm or less, the drying temperature can be lowered when forming the polyimide resin layer 22 using a method in which a polyimide resin composition containing a polyimide resin is applied and dried to solidify. Therefore, damage caused by drying the polyimide resin composition can be prevented. Furthermore, when forming the polyimide resin layer 22 using the above method, the solvent contained in the polyimide resin composition can be removed in a short time, allowing the polyimide resin layer 22 to be formed efficiently.

[0100] "Middle class" As shown in Fig. 1, the intermediate layer 23 is formed between the urethane resin layer 21 and the polyimide resin layer 22. The intermediate layer 23 is formed in contact with the urethane resin layer 21 and the polyimide resin layer 22. The intermediate layer 23 may be formed over the entire surface between the urethane resin layer 21 and the polyimide resin layer 22, or may be formed only partially. The intermediate layer 23 is formed by the urethane resin penetrating into the polyimide resin layer 22, thereby integrating the urethane resin layer 21 and the polyimide resin layer 22. The intermediate layer 23 improves the adhesion between the urethane resin layer 21 and the polyimide resin layer 22, making the urethane resin layer 21 and the polyimide resin layer 22 less likely to peel off, and making the resin composite laminate 10 less likely to crease when bent.

[0101] Intermediate layer 23 contains a urethane resin and a polyimide resin. When the resins contained in urethane resin layer 21 and polyimide resin layer 22 contain a resin other than a urethane resin and a polyimide resin, intermediate layer 23 may contain another resin corresponding to the resin contained in urethane resin layer 21 and polyimide resin layer 22.

[0102] The resin composite laminate 10 of this embodiment has a peel strength between the urethane resin layer 21 and the polyimide resin layer 22 of 1.6 N or more per 10 mm width, and preferably 3.5 N or more. A resin composite laminate 10 having a peel strength of 1.6 N or more per 10 mm width is less likely to peel between the urethane resin layer 21 and the polyimide resin layer 22 and is less likely to develop creases when bent, making it suitable as a base for a stretchable device.

[0103] The peel strength between the urethane resin layer 21 and the polyimide resin layer 22 is preferably 50 N or less per 10 mm width, and more preferably 10 N or less. A resin composite laminate 10 having a peel strength of 50 N or less per 10 mm width has good tensile strength because the reduction in strength of the polyimide resin layer 22 caused by forming the intermediate layer 23 between the urethane resin layer 21 and the polyimide resin layer 22 is minimal. When the resin composite laminate 10 has a width of less than 10 mm, the peel strength per 10 mm width is determined by converting the measured peel strength value into a peel strength per 10 mm width.

[0104] The resin composite laminate 10 of this embodiment preferably has a tensile strength per 10 mm of width of 0.2 to 4.35 N, more preferably 0.3 to 1.0 N. A tensile strength of 0.2 N or more per 10 mm of width results in a resin composite laminate 10 with sufficient strength. A resin composite laminate 10 with a tensile strength of 4.35 N or less per 10 mm of width has good flexibility, and stress is dispersed and not easily applied when bent or stretched, and stress differences are not easily generated between the urethane resin layer 21 and the polyimide resin layer 22. Therefore, the urethane resin layer 21 and the polyimide resin layer 22 are not easily peeled off, and creases are not easily formed when bent, making the resin composite laminate suitable as a base for a stretchable device. When the resin composite laminate 10 has a width of less than 10 mm, the measured tensile strength is converted into a tensile strength at a width of 10 mm, and the converted value is taken as the tensile strength per 10 mm width.

[0105] The resin composite laminate 10 of this embodiment preferably has an elongation per 10 mm of width of 20 to 100%, more preferably 40 to 80%. A resin composite laminate 10 with an elongation of 20% or more per 10 mm of width has good stretchability and is suitable as a base for a stretchable device. A resin composite laminate 10 with an elongation of 100% or less per 10 mm of width is preferred because the polyimide resin layer 22 is less likely to break when stretched. When the resin composite laminate 10 has a width of less than 10 mm, the measured elongation value is converted into the elongation per 10 mm width, and the converted value is taken as the elongation per 10 mm width.

[0106] The resin composite laminate 10 of this embodiment preferably has a thickness of 1 to 2000 μm, and may be, for example, 5 to 1000 μm. When the thickness of the resin composite laminate 10 is 1 μm or more, the strength of the resin composite laminate 10 is good. When the thickness of the resin composite laminate 10 is 2000 μm or less, the flexibility of the resin composite laminate 10 is good.

[0107] [Method of manufacturing resin composite laminate] The resin composite laminate 10 of this embodiment can be produced, for example, by the production method described below. "Solidified layer formation process" To produce the resin composite laminate 10 of this embodiment, first, a polyimide resin composition containing a polyimide resin is produced. The polyimide resin composition can be obtained, for example, by mixing a polyimide resin with a solvent and dissolving the polyimide resin in the solvent. Next, the polyimide resin composition is applied onto a substrate, and a solidified layer is formed from any one selected from a solidified material obtained by solidifying the polyimide resin composition by drying, a semi-cured material obtained by semi-curing the polyimide resin composition, and a partially cured material obtained by only partially curing the polyimide resin composition.

[0108] A known peelable substrate can be used as the substrate. Alternatively, a pre-manufactured resin composite laminate 10 or an element including the resin composite laminate 10 may be used as the substrate. In this case, a laminate in which multiple resin composite laminates 10 are stacked can be easily manufactured. This method is suitable for manufacturing a stretchable device in which multiple elements including the resin composite laminate 10 are stacked.

[0109] The method for applying the polyimide resin composition is not particularly limited, and for example, it can be applied by a known method using various coaters or a wire bar.

[0110] The state of the solidified layer can be selected from a solidified product solidified by drying, a semi-cured product semi-cured, and a partially cured product only partially cured, by appropriately adjusting the composition of the polyimide resin composition and the drying conditions or curing conditions of the applied polyimide resin composition.

[0111] When the polyimide resin composition is solidified by drying, the drying temperature is preferably 70 to 250°C, and may be, for example, 80 to 110°C. When the drying temperature is 70°C or higher, the resin composite laminate 10 can be produced efficiently. When the drying temperature is 250°C or lower, the substrate is not damaged by drying the polyimide resin composition, and the solvent can be removed while suppressing shrinkage of the solidified layer due to temperature changes.

[0112] The drying time of the polyimide resin composition can be appropriately set depending on the drying temperature, and can be, for example, 1 to 120 minutes, preferably 1 to 60 minutes. When the drying time is within this range, a solidified product having good properties can be efficiently produced. Completion of solidification (formation of a solidified layer) by drying the polyimide resin composition can be confirmed, for example, by performing thermogravimetric analysis and finding that no change in the mass of the polyimide resin composition being dried is observed.

[0113] When the polyimide resin composition is semi-cured to form a semi-cured product, it is preferably dried at 70 to 150°C, and then heated to 180 to 300°C in a nitrogen atmosphere to cure. When forming a semi-cured product, the heating time for curing is preferably 5 to 90 minutes, and more preferably 5 to 30 minutes. When the drying temperature, heating temperature, and heating time are within these ranges, a solidified product with good properties can be efficiently produced. When a polyimide resin composition is semi-cured to form a semi-cured product, the formation of the semi-cured product (solidified layer) can be confirmed, for example, by using one or more of the following methods: A thermogravimetric analysis is performed, and the thermogravimetric curve is compared with that of the cured film; A tensile test is performed, and the tensile strength is compared with that of the cured film; An electrical insulation test is performed, and the electrical insulation is compared with that of the cured film. It is necessary to use a semi-cured product while taking into consideration that the electrical insulation is lower than that of the cured film.

[0114] When the polyimide resin composition is only partially cured and the remaining portion is semi-cured, it is preferable to dry the composition at 70 to 150°C, and then heat cure the composition in a nitrogen atmosphere at 180 to 350°C for 20 to 120 minutes. When the drying temperature, heating temperature, and heating time are within these ranges, a solidified product with excellent properties can be efficiently produced. When a polyimide resin composition is only partially cured and the remaining portion is a semi-cured product, the formation of the partially cured product (solidified layer) can be confirmed, for example, by one or more of the thermogravimetric curve obtained by thermogravimetric analysis, the tensile strength value obtained by a tensile test, and the electrical insulation value obtained by an electrical insulation test.

[0115] "Intermediate layer formation process" Next, a urethane resin composition containing a urethane resin and a solvent is applied to part or all of the solidified layer and solidified. This allows the urethane resin to penetrate into the solidified layer and solidify. As a result, a urethane resin layer 21 and a polyimide resin layer 22 are formed, and an intermediate layer 23 integrated with the urethane resin layer 21 and the polyimide resin layer 22 is formed between the urethane resin layer 21 and the polyimide resin layer 22.

[0116] The method for applying the urethane resin composition is not particularly limited, and for example, known methods using various coaters or wire bars can be used.

[0117] As a method for solidifying the urethane resin composition, for example, a method of drying a solidified layer on which the urethane resin composition is applied can be used. The drying temperature for the urethane resin composition is preferably 25 to 150° C., and may be, for example, 70 to 120° C. When the drying temperature is 25° C. or higher, the resin composite laminate 10 can be efficiently produced. When the drying temperature is 150° C. or lower, damage such as deformation of the resin composite laminate 10 caused by an excessively high drying temperature is unlikely to occur, and this is preferable.

[0118] The drying time of the urethane resin composition may be appropriately set depending on the drying temperature, and is preferably 10 to 120 minutes, more preferably 10 to 90 minutes. When the drying time is within this range, a resin composite laminate 10 with good properties can be efficiently produced. Completion of solidification (formation of resin composite laminate 10) by drying the urethane resin composition can be confirmed, for example, by the fact that no clear change is observed in the mass of the resin composite laminate 10 being dried.

[0119] In the manufacturing method of this embodiment, the polyimide resin is preferably soluble in the solvent contained in the urethane resin layer composition. In the intermediate layer formation step, the urethane resin composition is preferably applied to dissolve the polyimide resin contained in the solidified layer in the solvent. In this case, applying the urethane resin composition allows both the urethane resin and the polyimide resin to be dissolved in the solvent while being solidified. As a result, an intermediate layer 23 containing both the urethane resin and the polyimide resin, in which the urethane resin penetrates into the polyimide resin layer 22 and is integrated with the urethane resin layer 21 and the polyimide resin layer 22, can be easily and reliably formed, resulting in a resin composite laminate 10 that is even more resistant to peeling and creases when bent.

[0120] In this embodiment, after the intermediate layer forming step, a step of curing the polyimide resin composition contained in the polyimide resin layer 22 may be carried out as necessary.

[0121] The resin composite laminate 10 of this embodiment includes a urethane resin layer 21 containing a solvent-soluble urethane resin having a urethane bond and a siloxane bond and a weight-average molecular weight of 52,200 to 260,000, and a polyimide resin layer 22 containing a polyimide resin having an imide bond, and the peel strength between the urethane resin layer 21 and the polyimide resin layer 22 is 1.6 N or more per 10 mm width. The resin composite laminate 10 of this embodiment also includes an intermediate layer 23 formed in contact with the urethane resin layer 21 and the polyimide resin layer 22, the urethane resin penetrating the polyimide resin layer 22 and integrating the urethane resin layer 21 and the polyimide resin layer 22. Therefore, the resin composite laminate 10 of this embodiment has good adhesion between the urethane resin layer 21 and the polyimide resin layer 22, making them less likely to peel off and less likely to develop creases when bent.

[0122] Furthermore, the resin composite laminate 10 of this embodiment has a urethane resin layer 21 containing a urethane resin having a urethane bond and a siloxane bond and a weight-average molecular weight of 52,200 to 260,000, and therefore has good stretchability. Furthermore, the resin composite laminate 10 of this embodiment has a polyimide resin layer 22 containing a polyimide resin having an imide bond, and therefore has good heat resistance. Specifically, it has heat resistance of 200°C plus several tens of degrees Celsius or more. Therefore, the resin composite laminate 10 of this embodiment is suitable as a base for a stretchable device.

[0123] The method for producing the resin composite laminate 10 of this embodiment includes a solidified layer forming step of forming a solidified layer consisting of one selected from a solidified product obtained by drying and solidifying a polyimide resin composition, a semi-cured product obtained by semi-curing a polyimide resin composition, and a partially cured product obtained by only partially curing a polyimide resin composition, and an intermediate layer forming step of applying a urethane resin composition containing a urethane resin and a solvent onto the solidified layer and solidifying it to form the intermediate layer 23 in contact with the urethane resin layer 21 and the polyimide resin layer 22. Therefore, the method for producing the resin composite laminate 10 of this embodiment can produce the resin composite laminate 10 of this embodiment, which has the urethane resin layer 21, the polyimide resin layer 22, and the intermediate layer 23 in which the urethane resin has penetrated the polyimide resin layer 22 and is integrated with the urethane resin layer 21 and the polyimide resin layer 22.

[0124] [Stretchable device] FIG. 2 is a schematic diagram showing an example of a stretchable device according to one embodiment of the present invention. The stretchable device 1 of this embodiment shown in Fig. 2 is configured by laminating a first sheet 11, a second sheet 12, a third sheet 13, and a fourth sheet 14 in this order in the thickness direction. In this specification, these four layers (sheets) of sheets may be collectively referred to as "first sheet 11 to fourth sheet 14." The first sheet 11 to the fourth sheet 14 are all elements including the resin composite laminate 10 described above.

[0125] The first sheet 11 is configured such that an electrode 111 is provided together with wiring on the surface of the resin composite laminate 10 facing the second sheet 12. The second sheet 12 is formed by embedding or attaching a copper-plated member 121 in the resin composite laminate 10. The second sheet 12 is provided with vias or connection portions for connecting to wiring on other sheets. The third sheet 13 is configured by embedding or mounting an electronic component 131 in the resin composite laminate 10. The third sheet 13 is provided with vias or connection parts for connecting to wiring on other sheets. The fourth sheet 14 is composed of only the resin composite laminate 10 .

[0126] The wiring and electrodes 111, copper-plated members 121, and electronic components 131 provided in the stretchable device 1 can be those known in the relevant field.

[0127] When the first sheet 11 to the fourth sheet 14 are stacked, the wiring and electrodes 111 on the first sheet 11 contact the copper-plated members 121 in the second sheet 12, and the copper-plated members 121 contact the electronic components 131 in the third sheet 13. The fourth sheet 14 is provided on the first sheet 11, the second sheet 12, and the third sheet 13 so that the wiring and electrodes 111, the copper-plated members 121, and the electronic components 131 are not exposed, and functions as a sealing layer.

[0128] The stretchable device 1 can be manufactured, for example, by laminating a first sheet 11, a second sheet 12, a third sheet 13, and a fourth sheet 14 in the stated order. When manufacturing the stretchable device 1, the order in which these sheets are stacked is not particularly limited.

[0129] The first sheet 11 can be manufactured, for example, by applying a conductive composition for forming wiring and electrodes 111 to one side of the resin composite laminate 10 by a printing method, and drying it to form a conductive layer.

[0130] The second sheet 12 can be manufactured, for example, by placing a copper-plated member 121 on the surface of the first sheet 11 on which the wiring and electrodes 111 are formed, and using this as a base material, forming the resin composite laminate 10 on the surface of the first sheet 11 on which the wiring and electrodes 111 are formed using the manufacturing method described above. At this time, the copper-plated member 121 is made to penetrate through the second sheet 12. Alternatively, the second sheet 12 may be produced by forming the resin composite laminate 10 on the surface of the first sheet 11 on which the wiring and electrodes 111 are formed, and then attaching the copper-plated member 121 onto the resin composite laminate 10.

[0131] The third sheet 13 can be produced, for example, by placing an electronic component 131 on the surface of the second sheet 12 opposite to the first sheet 11 side, and using this as a base material, forming the resin composite laminate 10 on the surface of the second sheet 12 opposite to the first sheet 11 side (i.e., the surface on which the electronic component 131 is placed). At this time, the electronic component 131 is made to penetrate through the third sheet 13. The fourth sheet 14 can be produced by using the third sheet 13 as a base material and forming the resin composite laminate 10 on the surface of the third sheet 13 opposite to the second sheet 12 side. Through the above steps, the stretchable device 1 of this embodiment shown in FIG. 2 is obtained.

[0132] The stretchable device of this embodiment is not limited to the stretchable device 1 shown in FIG. 2, and some of the configuration may be changed, deleted, or added within the scope that does not deviate from the spirit of the present invention. For example, the stretchable device 1 of this embodiment has four sheets, but it may have only one sheet or a number other than four, and the number of sheets in the stretchable device can be set as desired depending on the purpose of the stretchable device. Furthermore, in the stretchable device 1 of the present embodiment, the sheet including the resin composite laminate 10 includes wiring, electrodes, copper-plated members, or electronic components, but may also include other configurations.

[0133] The stretchable device 1 of the present embodiment may have a base material layer. The base material layer can be arbitrarily selected depending on the purpose of the stretchable device 1, and may be a known one, without any particular limitation. An example of the base layer is a release sheet having an adhesive layer for attaching the stretchable device 1 to an object of use. By attaching the release sheet to one or both surfaces of the stretchable device 1, the release sheet protects the stretchable device 1 during storage, and can be easily peeled off from the stretchable device 1 when the stretchable device 1 is to be used.

[0134] The stretchable device 1 of this embodiment has an element body including the resin composite laminate 10 of this embodiment. Therefore, the stretchable device 1 of this embodiment is resistant to creases even when folded, and has sufficient stretchability and heat resistance. For this reason, the stretchable device 1 of this embodiment is used in an environment where it is repeatedly stretched and contracted, and is suitable for applications where stress is applied due to changes in curved surfaces such as bending and rolling, and for applications where it stretches and contracts in accordance with body movement. Furthermore, the stretchable device of this embodiment is also suitable for mounting electronic components, thin-film sensors, etc. on the element body, and for applications where high power is used. Therefore, the stretchable device 1 of this embodiment can be suitably used in wearable devices, etc.

[0135] The above describes the embodiments of the present invention in detail, but each configuration and combination thereof in each embodiment is 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. [Example]

[0136] The present invention will be described in more detail below with reference to specific examples, although the present invention is not limited to the examples shown below.

[0137] The raw materials used in the production of the urethane resin composition are shown below. Resin (a) (a)-1: Urethane acrylate oligomer (product name: UN-5500, manufactured by Negami Chemical Industrial Co., Ltd.) ·Resin (b) (b)-1: Methacrylate-modified polydimethylsiloxane in which one end is modified with a methacryloyl group (product name: Silaplane (registered trademark) FM-0721, manufactured by JNC Corporation) Polymerization initiator (c) (c)-1: Dimethyl 2,2'-azobis(2-methylpropionate), azo polymerization initiator (product name: V601, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) RAFT agents (1)-1: RAFT agent represented by the following formula (1)-1 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) ·solvent MEK: Methyl ethyl ketone

[0138] [ka]

[0139] <Production of urethane resin composition> [Synthesis Example 1] Resin (a)-1 (100 parts by mass), resin (b)-1 (2 parts by mass), polymerization initiator (c)-1 (1.2 parts by mass), RAFT agent (1)-1 (2.946 parts by mass), and MEK were weighed into a flask and mixed at room temperature using a stirrer to obtain a raw material mixture. The amount of MEK used was adjusted so that the total content of components other than MEK was 24.6% by mass relative to the total amount of the raw material mixture.

[0140] The resulting mixture was cooled and solidified using liquid nitrogen, and the sealed flask was degassed under vacuum. The mixture was then dissolved in an oil bath under a nitrogen atmosphere, and the temperature was raised while stirring, and polymerization reaction was carried out at 90°C for 55 minutes. Thereafter, the reaction product was diluted with MEK to produce a urethane resin composition of Synthesis Example 1 containing 24.6% by mass of urethane resin.

[0141] [Synthesis Example 2] The reaction product was diluted with N,N-dimethylacetamide (DMAc) instead of MEK to produce a urethane resin composition of Synthesis Example 2 containing 24.6 mass% of the same urethane resin as in Synthesis Example 1.

[0142] [Synthesis Example 3] A polymerization reaction was carried out in the same manner as in Synthesis Example 1, except that the raw material mixture used contained 0.8 parts by mass of polymerization initiator (c)-1, and the polymerization reaction time was 180 minutes. Thereafter, the reaction product was diluted with N,N-dimethylacetamide (DMAc) to produce a urethane resin composition of Synthesis Example 3 containing 24.6% by mass of urethane resin.

[0143] [Synthesis Example 4] A polymerization reaction was carried out in the same manner as in Synthesis Example 1, except that the raw material mixture used contained 1.6 parts by mass of polymerization initiator (c)-1, and the polymerization reaction time was 30 minutes. Thereafter, the reaction product was diluted with N,N-dimethylacetamide (DMAc) to produce a urethane resin composition of Synthesis Example 4 containing 24.6% by mass of urethane resin.

[0144] The solvents (dilution solvents) used to dilute the reaction products in Synthesis Examples 1 to 4 are shown in Table 1.

[0145] [Table 1]

[0146] <Production of Polyimide Resin Layer> [Manufacturing Example 1] An aromatic polyimide resin having an aromatic polyimide as the main skeleton and consisting of an aliphatic hydrocarbon chain or an alicyclic skeleton was dissolved in N,N-dimethylacetamide (DMAc) to produce a polyimide resin composition of Production Example 1 containing 0.5 to 10 mass % of the polyimide resin. The polyimide resin composition of Production Example 1 was applied to a release film using a spray coater and dried at 90°C for 60 minutes to solidify the composition without causing a curing reaction. This procedure was repeated to form a solidified layer of Production Example 1 on the release film. Completion of solidification (formation of a solidified layer) by drying the polyimide resin composition was confirmed by thermogravimetric analysis, where the change in mass of the polyimide resin composition being dried was 2% by mass or less.

[0147] [Manufacturing Example 2] BPDA (3,3',4,4'-biphenyltetracarboxylic dianhydride) and a monomer having a silicone structure were polymerized to obtain a silicone-modified polyimide resin in which the silicone structure was bonded to the polyimide chain. The obtained silicone-modified polyimide resin was dissolved in N-methyl-2-pyrrolidone (NMP) to produce a polyimide resin composition of Production Example 2 containing 0.5 to 10 mass % of the polyimide resin.

[0148] The polyimide resin composition of Production Example 2 was applied to a glass substrate using an applicator and dried for 30 minutes at 80° C. Thereafter, a curing reaction was carried out in a drying oven under a nitrogen atmosphere at 200° C. for 30 minutes, and the composition was cooled to room temperature and peeled off from the glass substrate in water to form a solidified layer of Production Example 2 made of a semi-cured product. The formation of a semi-cured material (solidified layer) by semi-curing the polyimide resin composition was confirmed by taking three test specimens from the solidified layer of Production Example 2, conducting electrical insulation tests on each, and comparing the results with the electrical insulation test results for the cured film of the polyimide resin composition.

[0149] [Manufacturing Example 3] A diphenyl compound and an aromatic carboxylic acid were polymerized to obtain a polyamideimide resin, which is an isocyanate compound. The obtained polyamideimide resin was dissolved in N-methyl-2-pyrrolidone (NMP) to produce a polyimide resin composition of Production Example 3 containing 0.5 to 10 mass % of the polyimide resin. The polyimide resin composition of Production Example 3 was applied to a glass substrate using an applicator and dried for 30 minutes at 80° C. Thereafter, a curing reaction was carried out in a drying oven under a nitrogen atmosphere at 200° C. for 30 minutes, and the composition was cooled to room temperature and peeled off from the glass substrate in water to form a solidified layer of Production Example 3 made of a cured product. The formation of a cured product (solidified layer) by curing the polyimide resin composition was confirmed by taking three test specimens from the solidified layer of Production Example 3, performing tensile tests on each, and comparing the results with those of the tensile test on the cured film of the polyimide resin composition.

[0150] <Production of Resin Composite Laminate> [Example 1] The urethane resin composition of Synthesis Example 1 was applied onto the solidified layer of Production Example 1 having a thickness of 10 μm, and dried at 80° C. for 10 minutes to obtain a resin composite laminate of Example 1. [Example 2] The urethane resin composition of Synthesis Example 1 was applied onto the 10 μm thick solidified layer of Production Example 2, and dried at 80° C. for 10 minutes to obtain a resin composite laminate of Example 2.

[0151] [Example 3] The urethane resin composition of Synthesis Example 2 was applied onto the solidified layer of Production Example 1 having a thickness of 17 μm, and dried at 80° C. for 10 minutes to obtain a resin composite laminate of Example 3. [Example 4] The urethane resin composition of Synthesis Example 2 was applied onto the solidified layer of Production Example 1 having a thickness of 10 μm, and dried at 80° C. for 10 minutes to obtain a resin composite laminate of Example 4.

[0152] [Example 5] The urethane resin composition of Synthesis Example 3 was applied onto the solidified layer of Production Example 1 having a thickness of 10 μm, and dried at 80° C. for 10 minutes to obtain a resin composite laminate of Example 5. [Example 6] The urethane resin composition of Synthesis Example 4 was applied onto the solidified layer of Production Example 1 having a thickness of 10 μm, and dried at 80° C. for 10 minutes to obtain a resin composite laminate of Example 6. In Examples 1 to 6, completion of solidification by drying the urethane resin composition was confirmed by performing thermogravimetric analysis and finding that no change in the mass of the urethane resin composition being dried was observed.

[0153] [Comparative Example 1] The urethane-modified epoxy resin composition was applied to a metal foil using an applicator, dried at 80°C for 30 minutes, and then cured by heating at 130°C for 60 minutes to produce a urethane-modified epoxy resin layer with a thickness of 100 μm. The urethane-modified epoxy resin composition used contained 20 to 50 mass % of a urethane-modified epoxy resin obtained by dissolving a bisphenol A-type epoxy resin containing a urethane structure in a solvent. The urethane-modified epoxy resin layer thus obtained was laminated on the solidified layer of Production Example 1 having a thickness of 10 μm, thereby obtaining a resin composite laminate of Comparative Example 1.

[0154] Comparative Example 2 A 100 μm thick cured urethane resin was prepared containing a solvent-insoluble urethane resin, which was a polymer of hexane diisocyanate, 4,4-diphenylmethane diisocyanate, and a polyether compound. Then, the cured urethane resin was placed on the solidified layer of Production Example 1 with a thickness of 10 μm, which had been separately prepared, and subjected to a pressure of 50°C and 1000 kgf / cm 2 The cured urethane resin was attached onto the solidified layer by the pressure bonding method under the conditions of (a) to (c), thereby obtaining a resin composite laminate of Comparative Example 2.

[0155] Comparative Example 3 The urethane resin composition of Synthesis Example 1 was applied onto the 10 μm thick solidified layer (polyimide resin layer) of Production Example 3 and dried at 80° C. for 10 minutes to obtain a resin composite laminate of Comparative Example 3. In Comparative Example 3, completion of solidification by drying the urethane resin composition was confirmed by thermogravimetric analysis, whereby no change in the mass of the urethane resin composition being dried was observed.

[0156] For the resin composite laminates thus obtained in Examples 1 to 6 and Comparative Examples 1 to 3, the thickness of the urethane resin layer (urethane-modified epoxy resin layer in Comparative Example 1), the thickness of the polyimide resin layer, and the solvent contained in the polyimide resin composition are shown in Table 1. Furthermore, the weight average molecular weight (Mw) of the urethane resin, elongation per 10 mm width, and tensile strength were measured by the methods described below for the resin composite laminates of Examples 1 to 6 and Comparative Examples 1 to 3. The results are shown in Table 1.

[0157] "Measurement of weight average molecular weight (Mw) of urethane resin" The resin composite laminate was placed in a solvent, diethylene glycol monobutyl ether (BCA), and dissolved by heating and mixing to obtain a 15% by mass resin solution. The resulting resin solution was diluted 50 times with tetrahydrofuran (THF), mixed for 10 hours with a vibrator, and then filtered through a polytetrafluoroethylene (PTFA) filter. The solution that passed through the PTFA filter was used as a measurement sample for measuring the weight-average molecular weight of the urethane resin using gel permeation chromatography (GPC).

[0158] The weight-average molecular weight was measured using three GPC columns (product name: Shodex (registered trademark) LF-404, manufactured by Showa Denko K.K.) connected in series and a molecular weight analyzer (product name: Shodex (registered trademark) GPC-104, manufactured by Showa Denko K.K.). The temperature of the GPC column was set to 40°C, and tetrahydrofuran (THF) was used as the mobile phase to measure the weight-average molecular weight (Mw) of the measurement sample obtained above. The weight-average molecular weight was calculated using a calibration curve prepared in advance.

[0159] In addition, for the resin composite laminate of Comparative Example 2, the filtration pressure was high when filtering the resin solution using a PTFA filter, so there is a possibility that the measurement results of the weight average molecular weight (Mw) measured by the above method may have a large error.

[0160] "Stretch per 10mm width" Five strip-shaped measurement samples, each 10 mm wide and 35 mm long, were cut out from each resin composite laminate. The elongation of each measurement sample was calculated using the method described below, and the average value was taken as the elongation. 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 the time of break was measured, and the length before pulling (10 mm) was subtracted from the measured length to calculate the elongation.

[0161] "Tensile strength per 10mm width" Five strip-shaped measurement samples, each 10 mm wide and 35 mm long, were cut out from each resin composite laminate. The maximum tensile strength of each measurement sample was calculated using the method described below, and the average value was taken as the tensile strength. The 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 area 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.

[0162] Furthermore, samples corresponding to the resin composite laminates of Examples 1 to 6 and Comparative Examples 1 to 3 were prepared, and the peel strength per 10 mm width was measured by the method described below. The results are shown in Table 1.

[0163] "Peel strength per 10mm width" Samples of Examples 1 to 6 and Comparative Example 3, in which non-adhesive tape was placed in a portion between the urethane resin layer and the polyimide resin layer, were prepared in the same manner as the resin composite laminates of Examples 1 to 6 and Comparative Example 3, except that before applying the urethane resin composition to the solidified layer, a releasable non-adhesive tape was placed on the edge of the surface to be coated on the solidified layer.

[0164] In addition, a sample of Comparative Example 1 was prepared in the same manner as the resin composite laminate of Comparative Example 1, except that before laminating the urethane-modified epoxy resin layer on the solidified layer, a peelable non-adhesive tape was placed on the edge of the surface to be laminated on the solidified layer, and a non-adhesive tape was placed in a portion between the urethane-modified epoxy resin layer and the polyimide resin layer. In addition, a sample of Comparative Example 2 was prepared in the same manner as the resin composite laminate of Comparative Example 2, except that before placing the urethane resin cured material on the solidified layer, a peelable non-adhesive tape was placed on the edge of the surface to be placed on the solidified layer, and a non-adhesive tape was placed in a portion between the urethane resin layer and the polyimide resin layer.

[0165] Each sample was cut into a strip to obtain a test piece having a width of 10 mm and a length of 100 mm, in which non-adhesive tape was placed only in the region from approximately the center in the length direction to one end. The urethane resin layer side of each test piece was fixed to a resin substrate using double-sided tape to prevent air from getting in. The non-adhesive tape was then peeled off from the test piece, and the edge of the polyimide resin layer side was pulled in the opposite direction to the edge of the urethane resin layer side using a tensile tester (product name: FTN-13A, manufactured by Aiko Engineering Co., Ltd.) at a pulling speed of 5.0 mm / min. The tensile strength of five stable points excluding the start and end points was measured, and the average value was taken as the peel strength.

[0166] Furthermore, the resin composite laminates of Examples 1 to 6 and Comparative Examples 1 to 3 were observed for creases by the method described below and evaluated according to the criteria described below. The results are shown in Table 1.

[0167] "Fold urethane resin layer side" Each resin composite laminate was folded inward, and the two adjacent surfaces were pressed together across the fold line and held in contact for at least one second under conditions such that the angle between the two adjacent surfaces across the fold line (bending angle) was 0° and the bending radius R of the fold line was 0.01 mm or less. The force pressing the two adjacent surfaces together across the fold line was then released, and the laminate was left to stand until the angle between the two adjacent surfaces across the fold line became 180°, and the surface on the urethane resin layer side was visually inspected for the presence or absence of creases (fold marks).

[0168] "Fold polyimide resin layer side" Each resin composite laminate was folded in a valley shape so that the surface on the polyimide resin layer side was on the inside, and the two adjacent surfaces on either side of the fold line were pressed together and kept in contact for one second or more under conditions such that the angle between the two adjacent surfaces on either side of the fold line (bending angle) was 0° and the bending radius R of the fold line was 0.01 mm or less. After that, the force pressing the two adjacent surfaces on either side of the fold line together was released, and the laminate was left to stand until the angle between the two adjacent surfaces on either side of the fold line became 180°, and the surface on the polyimide resin layer side was visually observed for the presence or absence of creases (folding marks).

[0169] "Fold evaluation" A: No creases are formed on either the urethane resin layer side or the polyimide resin layer side. B: Creases are formed on the urethane resin layer side, but no creases are formed on the polyimide resin layer side. C: Creases were formed on both the urethane resin layer side and the polyimide resin layer side.

[0170] As shown in Table 1, the resin composite laminates of Examples 1 to 6 had a peel strength of 1.6 N or more, and the urethane resin layer and the polyimide resin layer were difficult to peel off from each other. Moreover, the resin composite laminates of Examples 1 to 6 were rated A or B in the crease evaluation. On the other hand, Comparative Example 1, which had a urethane-modified epoxy resin layer instead of a urethane resin layer, Comparative Example 2, in which a urethane resin layer containing a solvent-insoluble urethane resin was attached to a polyimide resin layer, and Comparative Example 3, which used a polyimide resin layer made of a cured product and therefore had no intermediate layer, all had insufficient peel strength and received a crease evaluation of C. [Industrial Applicability]

[0171] The present invention can be used for stretchable devices and their manufacture. [Explanation of symbols]

[0172] REFERENCE SIGNS LIST 1 stretchable device, 10 resin composite laminate, 11 first sheet, 12 second sheet, 13 third sheet, 14 fourth sheet, 111 electrode, 121 copper-plated member, 131 electronic component

Claims

1. a urethane resin layer containing a solvent-soluble urethane resin having a urethane bond and a siloxane bond and a weight average molecular weight of 52,200 to 260,000; a polyimide resin layer containing a polyimide resin that is soluble in the solvent and has an imide bond, the polyimide resin having an aromatic polyimide as a main skeleton and comprising an aliphatic hydrocarbon chain or an alicyclic skeleton, or a silicone-modified polyimide resin having a silicone structure bonded to a polyimide chain; A resin composite laminate, wherein the peel strength between the urethane resin layer and the polyimide resin layer is 1.6 N or more per 10 mm width.

2. 2. The resin composite laminate according to claim 1, wherein the urethane resin has a group represented by the following general formula (11), (21), or (31), a urethane bond, and a siloxane bond: 【Chemistry 1】 (In the formula, Z １ represents an alkyl group, and one or more hydrogen atoms in the alkyl group may be substituted with a cyano group, a carboxy group, or a methoxycarbonyl group, and the two or more substituents may be the same or different. ２ is an alkyl group. ３ is an aryl group. ４ is a hydrogen atom or a halogen atom. A bond marked with a symbol * is formed between the bond destination of the group represented by general formula (11), (21), or (31).

3. 3. The resin composite laminate according to claim 1, wherein the polyimide resin layer has a thickness of 10 μm or less.

4. The resin composite laminate according to any one of claims 1 to 3, having a tensile strength per 10 mm width of 4.35 N or less.

5. A method for producing the resin composite laminate according to any one of claims 1 to 4, a solidified layer forming step of forming a solidified layer made of any one selected from a solidified product obtained by solidifying a polyimide resin composition containing the polyimide resin by drying, a semi-cured product obtained by semi-curing the polyimide resin, and a partially cured product obtained by only partially curing the polyimide resin; a urethane resin composition containing the urethane resin and the solvent is applied to the solidified layer, followed by drying and solidifying the composition to form the urethane resin layer and the polyimide resin layer, and an intermediate layer forming step of forming an intermediate layer in contact with the urethane resin layer and the polyimide resin layer.

6. A method for manufacturing a resin composite laminate as described in Claim 5, wherein in the intermediate layer formation process, the urethane resin composition is applied to dissolve the polyimide resin contained in the solidified layer in the solvent.

7. A stretchable device having an element comprising the resin composite laminate according to any one of claims 1 to 4.

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