JP2023093906A - Conductive composition, conductor, stretchable conductor, electronic device - Google Patents

Abstract

To provide a conductive composition, a conductor, a stretchable conductor, and an electronic device excellent in repeating elongation resistance by effectively suppressing generation of crack during elongation, further excellent in conductivity, high-temperature and high-humidity resistance, and printability on an extensible film substrate.SOLUTION: A conductive composition comprising a block copolymer (E) mainly composed of structural units derived from an ethylenically unsaturated monomer having a weight average molecular weight of 20,000 or more and 500,000 or less, and conductive fine particles (F), wherein a content of the conductive fine particles (F) is 60 to 95 mass% with respect to a total solid content contained in the conductive composition, and among the conductive fine particles (F), the content of the chain-shaped silver powder (f1) is 20 mass% or more and less than 70 mass% with respect to the total solid content of the conductive composition, and the tap density of the chain-shaped silver powder (f1) is 2.0 g/cm3 or less.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a conductive composition, a conductor, a stretchable conductive material, and an electronic device.

Electrically conductive materials are used in various industrial fields, and various proposals have been made for further enhancing the functionality of these materials. Especially in recent years, the development of stretchable conductive materials with flexibility and stretchability has progressed, and proposals have been made for actuator applications and wearable sensor applications.
Patent Document 1 discloses a stretchable conductive film that is low in cost and has high durability. It is disclosed that high electrical conductivity is obtained when stretched.
Patent Literature 2 discloses a conductive composition capable of obtaining a conductor with remarkably improved stretchability by combining a block copolymer and a specific silver powder.

WO2018/159374 WO2017/026130

Along with the progress in fields such as healthcare devices such as bio-sensing, wearable devices, and robotics, conductive materials are not only required to be conductive, but also have properties that can be applied to curved surfaces and moving parts during processing and use. Followable stretchability is required.

Moreover, when a conductive material is used for the curved surface portion and the movable portion, there is a problem that cracks are likely to occur in the resin due to structural destruction of the resin accompanying repeated expansion and contraction. In particular, in the case of conductive materials, conductive fine particles are added in most cases, and the conductive material peels off from the resin during deformation due to elongation and contraction, creating voids in the resin, and cracks starting from these voids. likely to occur. As a result, there is a problem that the electrical conductivity decreases with repeated expansion and contraction.
Furthermore, in order to form a stretchable conductive material, it is necessary to apply a conductive composition such as a paste to the stretchable substrate to form a printed pattern. However, there is a problem that depending on the conductive composition to be used, aggregates are generated and the printability on various stretchable film substrates is deteriorated.

The present invention has been made in view of the above background, and is excellent in repeated stretching resistance by effectively suppressing the occurrence of cracks during stretching, and is also conductive, moist and heat resistant, and can be printed on a stretchable film substrate. An object of the present invention is to provide a conductive composition, a conductor, a stretchable conductive material, and an electronic device having good properties.

As a result of extensive studies, the inventors have found that the following aspects can solve the problems of the present invention, and have completed the present invention.

That is, the present invention has a weight average molecular weight of 20,000 or more and 500,000 or less.
a block copolymer (E) mainly composed of structural units derived from an ethylenically unsaturated monomer;
A conductive composition containing conductive fine particles (F),
The content of the conductive fine particles (F) is 60 to 95% by mass with respect to the total solid content contained in the conductive composition, and among the conductive fine particles (F), chain-shaped silver powder (f1) is 20% by mass or more and less than 70% by mass with respect to the total solid content of the conductive composition,
The present invention relates to a conductive composition, wherein the chain-like silver powder (f1) has a tap density of 2.0 g/cm ³ or less.

In addition, the present invention further contains flaky silver powder (f2), and the content of the flaky silver powder (f2) is 1 to 75% by mass with respect to the total solid content of the conductive composition. , relates to the conductive composition.

Further, in the present invention, the structure of the block copolymer (E) is a triblock structure represented by the following formula (1) or a star block structure represented by the following formula (2). relating to sexual compositions.
Formula (1)...polymer block A-polymer block B-polymer block A
Formula (2) [polymer block A-polymer block B] _q X
(In formula (1) above, the glass transition temperature of polymer block A is 20°C or higher, and the glass transition temperature of polymer block B is lower than 20°C. In formula (2) above, polymer block A The glass transition temperature of [polymer block B] _q X is 20° C. or higher, the glass transition temperature of [polymer block B] q is lower than 20° C., q is an integer of 2 or more and 6 or less, and X is an initiator residue and/or cup It is a ring agent residue or its derivative.)

The present invention also provides the above conductive composition, wherein the block copolymer (E) has one or more reactive functional groups selected from the group consisting of a mercapto group, a hydroxy group, an amino group, and a carboxy group. Regarding.

The present invention also relates to the conductive composition, further comprising a cross-linking agent (D) capable of cross-linking with the reactive functional groups of the block copolymer (E).

The present invention also relates to the conductive composition, wherein the block copolymer (E) contains a sulfur atom.

The present invention also relates to a conductor containing the conductive composition.

The present invention also relates to a conductor obtained by forming a cured product of the conductive composition on a stretchable substrate.

The present invention also relates to a stretchable conductive material comprising the above conductor.

The present invention also relates to an electronic device comprising the above conductor or stretchable conductive material.

According to the present invention, a conductive composition that is excellent in repeated stretching resistance by effectively suppressing the occurrence of cracks during stretching, and has good conductivity, moist heat resistance, and good printability on a stretchable film substrate. It has an excellent effect of being able to provide a conductor, a stretchable conductive material, and an electronic device.

Hereinafter, the conductive composition, the conductor, the stretchable conductive material, and the electronic device according to this embodiment will be described in detail in order.
In this embodiment, the cured product includes not only a product cured by a chemical reaction but also a product cured by a method other than a chemical reaction such as volatilization of a solvent.

<Conductive composition>
The electrically conductive composition of the present invention comprises a block copolymer (E) having a weight average molecular weight of 20,000 or more and 500,000 or less and mainly comprising structural units derived from an ethylenically unsaturated monomer; and a conductive fine particle (F), wherein the conductive fine particle (F) is 60 to 95% by mass with respect to the total solid content contained in the conductive composition, and Among them, the chain-shaped silver powder (f1) in which fine particles are aggregated to form aggregated particles is 20 to less than 70% by mass with respect to the total solid content of the conductive composition, and the chain-shaped silver powder (f1 ) has a tap density of 2.0 g/cm ³ or less.

<Block copolymer (E)>
The conductive composition of the present embodiment contains a binder block copolymer (E) in order to impart film-forming properties and adhesion to the stretchable substrate film. In addition, in this embodiment, by containing the block copolymer (E), flexibility and stretchability can be imparted to the conductive layer. Therefore, by containing the block copolymer (E), disconnection of the conductive layer due to stretching or contraction is suppressed.

The block copolymer (E) is a block copolymer mainly composed of structural units derived from ethylenically unsaturated monomers, and has a weight average molecular weight of 20,000 or more and 500,000 or less.

As used herein, the term "ethylenically unsaturated monomer" refers to a monomer having one or more polymerizable ethylenically unsaturated groups in the molecule. In addition, the term "mainly" means that 70% by mass or more of structural units derived from ethylenically unsaturated monomers are contained based on the total mass of the block copolymer.

Specific examples of ethylenically unsaturated groups in ethylenically unsaturated monomers include ethylene group, propenyl group, butenyl group, vinylphenyl group, (meth)acrylic group, allyl ether group, vinyl ether group, maleyl group, maleimide groups, (meth)acrylamide groups, acetylvinyl groups and vinylamide groups. The "ethylenically unsaturated monomer" is more preferably a (meth)acrylic group. "(Meth)acryl" includes both "acryl", "methacryl" and mixtures thereof. Also, "(meth)acrylate" includes both "acrylate", "methacrylate" and mixtures thereof.

In addition, in the present specification, the "structural unit derived from an ethylenically unsaturated monomer" includes, in addition to the residue of the ethylenically unsaturated monomer, a portion of the residue of the ethylenically unsaturated monomer. Also included are derivatives of residues of ethylenically unsaturated monomers obtained by reaction with reactive compounds during or after polymerization of the copolymer. For example, structural units in which functional groups and/or substituents not originally contained in the monomer are introduced into a portion of the residue of the ethylenically unsaturated monomer are also included. In addition, the monomer itself may contain a functional group and/or a substituent. It also includes a structure in which side groups, side chains, or a side group and a side chain in the block copolymer are bonded to each other or via a reactive compound to form a ring.

[Structure of block copolymer (E)]
The block copolymer (E) of the present embodiment preferably contains soft segments and hard segments. A soft segment is a block component composed of a flexible and highly flexible polymer chain, and a hard segment is a block component composed of a polymer chain that tends to crystallize or aggregate and has higher rigidity than the soft segment. In the block copolymer according to the present embodiment, a configuration in which a soft segment is sandwiched between hard segments (that is, a triblock structure of "hard segment - soft segment - hard segment" or a star block structure described later) is used. It is preferable to have

Block copolymers containing soft segments and hard segments include block copolymers represented by the following formula (3).
polymer block A-polymer block B (3)
In formula (3), polymer block A is a block (hard segment) with a glass transition point Tg of 20°C or higher, and polymer block B is a block (soft segment) with a glass transition point Tg of less than 20°C. By using the block copolymer represented by formula (3), the cured product of the conductive composition according to the present embodiment exhibits toughness. The glass transition point Tg can be measured using differential scanning calorimetry (DSC).
In this specification, formula (3) may be abbreviated as "AB".

Block copolymers having a triblock structure include block copolymers represented by the following formula (1).

Polymer block A—Polymer block B—Polymer block A (1)
In the formula (1), the description of the formula (3) can be used for the polymer block A and the polymer block B.
In this specification, formula (1) may be abbreviated as "ABA".

The polymer block A preferably has a Tg of 50°C or higher, and the polymer block B preferably has a Tg of -20°C or lower.

In the block copolymers represented by the formulas (3) and (1), the polymer block B having a lower glass transition point Tg corresponds to the soft segment, and the polymer block A having a higher glass transition point Tg corresponds to the soft segment. Preferably, it is a block corresponding to a hard segment.
When formula (3) and formula (1) are compared, it is preferable to use the block copolymer of formula (1) from the viewpoint of tensile elongation at break.

The block copolymer is preferably solid at least in the range of 20°C or higher and 30°C or lower. By being solid within this temperature range, good tackiness can be ensured when applied to a flexible substrate or when dried after application.

Also, the mass ratio of polymer block A to polymer block B is preferably in the range of 15:85 to 40:60. When the mass ratio of the polymer block A and the polymer block B is within the above range, the polymer block follows the substrate during elongation and disconnection is less likely to occur. More preferably, it is 20:80 to 35:75.

Examples of polymer block A include polymethyl methacrylate (PMMA) and polystyrene (PS). Examples of polymer block B include poly n-butyl acrylate (PBA) and polybutadiene (PB). The block copolymer is preferably a polymethyl (meth)acrylate/poly n-butyl (meth)acrylate/polymethyl (meth)acrylate triblock copolymer. In the present application, (meth)acrylate is a generic term for acrylate and methacrylate, and the same applies to other similar expressions.

Further, the block copolymer (E) may have a star-shaped block structure represented by the following formula (2), in addition to the block structures represented by the above formulas (3) and (1).

[polymer block A-polymer block B] _q X (2)
In formula (2), q is an integer of 2 or more and 6 or less. For polymer block A and polymer block B, the description of formula (3) can be used.
"Star block structure" means a plurality (2 to 6) of polymer block A-polymer block B diblocks bound together with X as the starting point (X and polymer block B bound together). [Polymer Block A-Polymer Block B] Refers to the structure of _qX . X is an initiator residue and/or a coupling agent residue, or a derivative thereof.
In this specification, formula (2) may be abbreviated as "[AB] _q X".

Furthermore, the term "initiator residue" refers to a partial structure derived from an initiator, and means a residue derived from the initiator in the block copolymer. The term "coupling agent residue" refers to a partial structure derived from the coupling agent, and means a residue derived from the coupling agent in the block copolymer. Moreover, the term "derivative thereof" refers to a structure in which a part of the initiator residue and/or the coupling agent residue is chemically converted. For example, it includes a structure in which a part of the initiator residue and/or the coupling agent residue is substituted or added during synthesis of the block copolymer.

The molecular weight of the initiator residue and/or the coupling agent residue in the case of the star block structure, or the derivative X thereof is not particularly limited within the scope of the present invention. For example, it can be about 50 to 2,500. Similarly, the molecular weight of the initiator residue or derivative thereof which may optionally be present at the chain end of the polymer block A is not particularly limited within the scope of the present invention, and is, for example, about 50 to 2,500. can be

The Tg of the polymer block A in the present specification is the Tg of <polymer block A> _Total observed in the curve obtained by differential scanning calorimetry (DSC) measurement at the stage when the block copolymer is obtained. , JIS K7121: 2012, the measurement method for the transition temperature of plastics, and the value obtained from the extrapolated glass transition start temperature (Tig) described in JIS 9.3. <Polymer Block A> Since the Tg derived from _Total is the same as or close to the Tg of a polymer that is not a block having a similar chemical structure, in the case of a diblock structure or triblock structure, the polymer block The Tg of B is readily distinguished from that of [polymer block B] _q X in the case of star block structures. <Polymer Block A> The above Tg of _Total and the Tg of each polymer block A do not vary greatly depending on the structure of the chain end of the block copolymer, that is, the chain end of the polymer block A. In the specification, the Tg of each polymer block A and the Tg of <polymer block A> _Total including the chain ends of the polymer block (A) are determined.

However, in cases such as when the structural units derived from the monomers of each polymer block A are different for each block, when multiple Tg values are observed in the curve obtained by DSC measurement, <polymer block Tg of each polymer block A shall be used instead of Tg of A> _Total . In that case, Tg is obtained by sampling when the polymerization of each polymer block A is completed. Alternatively, since there is a correlation with the Tg of the polymer having the same chemical structure as each polymer block (A), the Tg of each corresponding polymer is obtained from the Fox equation, and whether the Tg is 20° C. or higher. You may judge by whether or not. The Fox equation is a value obtained from the following equation (4).
1/(TgA+273.15)=Σ[Wa/(Tga+273.15)] (4)
In formula (4), TgA is Tg (°C) of polymer block A, Wa is the mass fraction of monomer a constituting polymer block A, and Tga is a homopolymer of monomer a. (homopolymer) Tg (°C). Note that Tga is widely known as a characteristic value of homopolymers, and for example, the value described in "POLYMER HANDBOOK, THIRDEDITION" or the manufacturer's catalog value can be used.

In the present specification, the Tg of the polymer block B is the Tg of the polymer block B itself when the block copolymer has a diblock structure or a triblock structure, and [polymer block B ] Let _q be the Tg of X. Here, polymer block B having a diblock structure, triblock structure, and [polymer block B] _q X having a star block structure are collectively referred to as <polymer block B[X]>.
The Tg of the <polymer block B[X]> is the Tg of the <polymer block B[X]> observed in the curve obtained by DSC measurement at the stage of obtaining the block copolymer, and is JISK7121: 2012, the measurement method for the transition temperature of plastics, and the value obtained from the extrapolated glass transition start temperature (Tig) described in JIS 9.3. The Tg of <polymer block B[X]> is the same as or close to the Tg of a polymer having a similar chemical structure, so it can be easily distinguished from the Tg derived from polymer block A.

The block copolymer preferably has an AB diblock structure, an ABA triblock structure, or a [AB] _q X star block structure, and the polymer block The chain end of A may have an initiator residue or a derivative thereof, a functional group, an inert group, a crosslinkable group, a substituent, or the like.

The Tg of the polymer block A is 20° C. or higher, preferably 40° C. or higher, more preferably 60° C. or higher, still more preferably 80° C. or higher, particularly 100° C. or higher. preferable. The upper limit of the Tg of the polymer block A is not particularly limited, but can be, for example, 300°C, 250°C or 200°C. The Tg of this polymer block A can be read as the Tg of <polymer block A> _Total as described above (the same applies hereinafter). That is, <polymer block A> _Total is 20° C. or higher, preferably 40° C. or higher, more preferably 60° C. or higher, further preferably 80° C. or higher, and 100° C. or higher. is particularly preferred. Similarly, the upper limit of <polymer block A> _Total is not particularly limited, but can be, for example, 300°C, 250°C, or 200°C.

The Tg of polymer block B for diblock, triblock structures, and the Tg of [polymer block B] _q X for star block structures, i.e., the Tg of <polymer block B[X]> is , less than 20° C., preferably −10° C. or less, particularly preferably −20° C. or less. Although the lower limit of Tg of <polymer block (B) [X]> is not particularly limited, it can be -100°C, -90°C or 80°C, for example.

The temperature difference between Tg of polymer block A and Tg of <polymer block B[X]> is not particularly limited, but is preferably 75°C or higher, more preferably 100°C or higher, and still more preferably 125°C or higher. Particularly preferably, it is 150° C. or higher. By setting the temperature to 75° C. or higher, the formation of a microphase-separated structure can be promoted, and the effect of physical cross-linking can be more effectively brought out.

The weight-average molecular weight (Mw) referred to in this specification is a value determined by the method described in Examples below. Mw of the block copolymer (E) is set to 20,000 or more and 500,000 or less. By setting it as this range, when a block copolymer is used as an electrically conductive composition for stretchable electrically-conductive materials, both elastic strength and electrical conductivity stability can be achieved. A preferred range for Mw is 25,000 to 400,000, and a more preferred range is 30,000 to 300,000. The polydispersity (Mw/Mn) is not particularly limited, but is preferably from 1 to 2.5, more preferably from 1 to 2.0, even more preferably from 1 to 1.8. From the viewpoint of promoting the formation of a microphase-separated structure that affects strength, it is particularly preferable to set the polydispersity to 1 to 1.5, 1 to 1.3.

Mw of each polymer block A may be different, but preferably substantially the same from the viewpoint of stretchability. Similarly, Mw of each polymer block B may be different, but preferably substantially the same from the viewpoint of stretchability.

Structural units derived from monomers of each polymer block A may be composed of structural units derived from different monomers for each block, or structural units derived from the same monomers between blocks. It may be composed of The polymer blocks A preferably share 60% by mass or more, more preferably 70% by mass, and 80% by mass or more of structural units derived from monomers in common. More preferably. Similarly, each polymer block B may be composed of structural units derived from different monomers for each block, or may be composed of structural units derived from the same monomer between blocks. good. Preferably, the polymer blocks B share 60% by mass or more of structural units derived from monomers in common, more preferably 70% by mass in common, and 80% by mass or more. are more preferably common. Here, "common" means that the components are common regardless of the sequence of the monomers.

The binding form of the block copolymer (E) is the ABA type triblock structure, [ Among AB] _q X, a bi-branched structure with q=2 and a tri-branched structure with q=3 are preferred. Polymer block A and polymer block B each independently have structural units derived from one type or two or more types of monomers.

The content of structural units derived from ethylenically unsaturated monomers in the block copolymer (E) is 70% by mass or more, preferably 80% by mass or more, relative to the total mass of the block copolymer. Preferably, more preferably 85% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more, the formation of the microphase-separated structure of the polymer block A and the polymer block B is more effectively performed. From the viewpoint of promoting, structural units other than X (initiator residue and / or coupling agent residue, or derivative thereof) and the terminal structure of the block copolymer are derived from ethylenically unsaturated monomers ( 100% by weight) is preferred.

The polymer block A is a block that satisfies the above Tg and functions as a hard segment mainly composed of structural units derived from ethylenically unsaturated monomers. A monomer is used individually by 1 type or in combination of 2 or more types. Specific examples of monomers include methacrylate, acrylamide, N-alkylacrylamide, styrene, styrene derivatives, maleimide and acrylonitrile. Examples of methacrylic acid esters include those having an alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Examples of styrene derivatives include α-methylstyrene, t-butylstyrene, p-chlorostyrene, chloromethylstyrene and vinyltoluene. Moreover, a monomer exemplified for the polymer block B described below can be suitably included as a part thereof.

The polymer block B is a block that satisfies the above Tg and functions as a soft segment mainly composed of structural units derived from ethylenically unsaturated monomers. A monomer is used individually by 1 type or in combination of 2 or more types. Specific examples of monomers include acrylic acid esters, olefin compounds, diene compounds, and alkylene oxides. Examples of acrylic acid esters include alkyl acrylates having an alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Examples of olefin compounds and diene compounds include olefin compounds and diene compounds having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Examples of alkylene oxides include alkylene oxides having an alkylene group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Moreover, the monomers exemplified in the above-mentioned polymer block A can be suitably included as a part thereof.

As a suitable example of the block copolymer (E), the polymer block A contains 50% by mass or more of a structural unit derived from a methacrylate, and the polymer block B contains 70% by mass or more of a structural unit derived from an acrylic ester. A copolymer is mentioned. The methacrylic acid ester-derived structural unit in the polymer block A is more preferably 60% by mass or more, still more preferably 70% by mass or more, 80% by mass or more, and 90% by mass or more. Moreover, it is good also considering the structural unit derived from methacrylic acid ester as 100 mass %.

Further, the acrylic ester-derived structural unit in the polymer block B is more preferably 80% by mass or more, still more preferably 85% by mass or more, 90% by mass or more, and 95% by mass or more. Moreover, it is good also considering the structural unit derived from acrylic acid ester as 100 mass %. Polymer block A contains 50% by mass or more of a methacrylate-derived structural unit, and polymer block B contains 70% by mass or more of an acrylic ester-derived structural unit. Stretch conductivity can be expressed.

Examples of monomers forming a structural unit derived from a methacrylate of polymer block A include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, normal butyl methacrylate, isobutyl methacrylate, tertiary butyl methacrylate, isoamyl methacrylate, pentyl methacrylate, Normal hexyl methacrylate, isohexyl methacrylate, isoheptyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate, normal octyl methacrylate, isononyl methacrylate, isodecyl methacrylate, lauryl methacrylate, tetradecyl methacrylate, octadecyl methacrylate, behenyl methacrylate, isostearyl methacrylate, cyclohexyl methacrylate, t-butylcyclohexylmethyl methacrylate, isobornyl methacrylate, trimethylcyclohexyl methacrylate, cyclodecyl methacrylate, cyclodecylmethyl methacrylate, benzyl methacrylate, t-butylbenzotriazole phenylethyl methacrylate, phenyl methacrylate, naphthyl methacrylate, allyl methacrylate and the like can be exemplified by aliphatic, alicyclic and aromatic alkyl methacrylates.
hydroxyalkyl methacrylates having 2 to 4 carbon atoms in the hydroxyalkyl group such as 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate; methacrylic acid-based monomers containing a hydroxyl group such as glycerin acrylate and glycerin methacrylate; Alkoxyalkyl methacrylates in which the alkoxy group has 1 to 4 carbon atoms and the alkyl group has 1 to 4 carbon atoms, such as methacrylate, methoxyethyl methacrylate, methoxypropyl methacrylate, ethoxymethyl methacrylate, ethoxyethyl methacrylate, ethoxypropyl methacrylate, etc. alkoxyalkyl methacrylates of;
(Polyalkylene) glycol monoalkyl, alkylene, alkyne ether or ester monomethacrylates; methacrylic acid-based monomers having an acid group (carboxy group, sulfonic acid, phosphoric acid) including acrylic acid and acrylic acid dimers; oxygen Atom-containing methacrylic acid-based monomers; amino group-containing methacrylic acid-based monomers; nitrogen atom-containing methacrylic acid-based monomers and the like can be used. In addition, monomethacrylates having 3 or more hydroxyl groups, halogen atom-containing methacrylates, silicon atom-containing methacrylic acid-based monomers, methacrylic acid-based monomers having a group that absorbs ultraviolet rays, α-hydroxyl group methyl-substituted acrylates can also be exemplified. Methacrylic acid monomers having two or more addition polymerizable groups, such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and methacrylic acid esters of polyalkylene glycol adducts of trimethylolpropane, may also be used.

As the monomer forming the structural unit other than the methacrylic acid ester-derived structural unit of the polymer block A, other monomers capable of being polymerized with the methacrylic acid ester can be used. Specific examples include styrene and acrylonitrile.

A suitable example of the polymer block A includes an aspect containing 50% by mass or more of structural units derived from methyl methacrylate. More preferably, the structural unit derived from methyl methacrylate is 60% by mass or more, and more preferably 80% by mass or more. Further, 100% by mass of polymer block A may be a structural unit derived from methyl methacrylate.

Examples of monomers forming acrylic acid ester-derived structural units of polymer block B include methyl acrylate, ethyl acrylate, propyl methacrylate, isopropyl methacrylate, normal butyl acrylate, isobutyl acrylate, tertiary butyl acrylate, isoamyl acrylate, pentyl acrylate, Normal hexyl acrylate, isohexyl acrylate, isoheptyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, normal octyl acrylate, isononyl acrylate, isodecyl acrylate, lauryl acrylate, tetradecyl acrylate, octadecyl acrylate, behenyl acrylate, isostearyl Acrylates, cyclohexyl acrylate, t-butylcyclohexylmethyl acrylate, isobornyl acrylate, trimethylcyclohexyl acrylate, cyclodecyl acrylate, cyclodecylmethyl acrylate, benzyl acrylate, t-butylbenzotriazole phenylethyl acrylate, phenyl acrylate, naphthyl acrylate, allyl acrylate Examples include aliphatic, alicyclic and aromatic alkyl acrylates such as
In addition, acrylic acid-based monomers containing a hydroxyl group; acrylic acid-based monomers having a glycol group; (polyalkylene) glycol monoalkyl, alkylene, alkyne ether or ester monoacrylates; acrylic acid and acrylic acid dimers. acrylic acid monomers containing acid groups (carboxy group, sulfonic acid, phosphoric acid); oxygen atom-containing acrylic acid monomers; amino group-containing acrylic acid monomers; nitrogen atom-containing acrylic acid monomers etc. can be used. In addition, monoacrylates having 3 or more hydroxyl groups, halogen atom-containing acrylates, silicon atom-containing acrylic acid monomers, UV-absorbing acrylic acid monomers, α-hydroxyl group methyl-substituted acrylates can also be exemplified. Acrylic acid monomers having two or more addition polymerizable groups, such as ethylene glycol diacrylate, diethylene glycol diacrylate, acrylic acid esters of polyalkylene glycol adducts of trimethylolpropane, and the like, may also be used.

As the structural unit other than the acrylic acid ester-derived structural unit of the polymer block B, other monomers that can be polymerized with the acrylic acid ester can be used. Examples include maleic acid, itaconic acid, crotonic acid and the like.

A suitable example of the polymer block B includes an aspect containing 70% by mass or more of structural units derived from butyl acrylate. More preferably, the structural unit derived from butyl acrylate is 80% by mass or more, and more preferably 90% by mass or more. Further, 100% by mass of the polymer block B may be structural units derived from butyl acrylate.

As a suitable example of the block copolymer (E), the polymer block A contains 50% by mass or more of the structural unit derived from methyl methacrylate, and the polymer block B contains 70% by mass or more of the structural unit derived from butyl acrylate. The aspect containing can be illustrated. An excellent stretchable conductive material can be provided by using such a block copolymer as the block copolymer (E). The structural unit derived from methyl methacrylate in polymer block A may be 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 100% by mass or more. The structural unit derived from butyl acrylate in polymer block B may be 80% by mass or more, 90% by mass or more, or 100% by mass.

By using the block copolymer (E), the polymer block A and the polymer block B can have a phase separation structure (microscopic phase separation structure) can be formed. By forming a microphase-separated structure, it is possible to provide a conductive composition that imparts excellent stretchability and can effectively suppress the occurrence of cracks (disconnection) due to stretching. From the viewpoint of more effectively increasing stretchability, it is more preferable to have a sea-island structure in which the polymer block A corresponds to an island and the polymer block B corresponds to the sea. The microphase separation structure can be confirmed by observation using an atomic force microscope (AFM).

The content of the polymer block A relative to the polymer block A and the polymer block B of the block copolymer (E) is not particularly limited, but from the viewpoint of easily obtaining a microphase-separated structure of a sea-island structure, it is 1 to 50 mass. %, more preferably 15 to 30% by mass. Further, from the viewpoint of effectively drawing out the adhesiveness, the content of the entire polymer block A with respect to the polymer block A and the polymer block B in the block copolymer is preferably 1 to 35% by mass. More preferably, it is up to 30% by mass.
The content ratio of the polymer block A and the polymer block B in the block copolymer is not particularly limited, but from the viewpoint of easily obtaining a microphase-separated structure, the total mass of the block copolymer is The content of A and polymer block B is preferably 90.0 to 99.9% by mass, more preferably 98.0 to 99.9% by mass.

In the block copolymer (E), from the viewpoint of maintaining good conductivity, 90% by mass or more of the ethylenically unsaturated monomers in the block copolymer are preferably hydrophobic ethylenically unsaturated monomers. preferable. Here, "hydrophobic ethylenically unsaturated monomer" refers to a monomer having a solubility in water at 20°C of 6.5 g/100 mL or less. Examples of the hydrophobic ethylenically unsaturated monomer include alkyl (meth)acrylates, olefins such as butadiene and isoprene, vinyls such as vinyl acetate and vinyl chloride, and aromatics such as styrene. .

[Functional group]
Block copolymer (E) may have a functional group. Examples of functional groups include mercapto groups, hydroxy groups, amino groups, carboxy groups, glycidyl groups, (meth)acryl groups, hydrolyzable silyl groups, nitrile groups, and isocyanate groups.

[Reactive functional group]
Among the above functional groups, the block copolymer (E) preferably has one or more reactive functional groups selected from the group consisting of mercapto groups, hydroxy groups, amino groups and carboxy groups. By using the functional group as a reactive functional group and combining it with a cross-linking agent (D) described later and chemically cross-linking it, the block copolymer (E) can be three-dimensionally cross-linked, and the conductive layer is required to have hardness. Can be preferably used in.

[Sulfur atom]
The block copolymer (E) preferably contains a sulfur atom from the viewpoint of effectively suppressing the occurrence of cracks when it contains a conductive filler such as a metal filler. more preferably derived from a group, a mercapto group, or the like.

When the block copolymer (E) contains a sulfur atom in the molecule, the polymer block A and the polymer block B forming the block copolymer (E) form a microphase-separated structure, resulting in stress relaxation. Physical bridges can be formed that can form structures containing points. The block copolymer (E) can have excellent stretchability by having a microphase-separated structure and forming physical crosslinks. Also, the sulfur atoms can be brought closer together by self-assembly (aggregation of segments). Such a distribution of sulfur atoms can further impart cohesive force and stress relaxation, and can impart superior stretchability, heat resistance, and moist heat resistance to the block copolymer (E).

As a method for incorporating sulfur atoms into the block copolymer (E), for example, a method of directly introducing using a monomer having a sulfur atom, and a method of introducing a monomer using a polymerization initiator having a sulfur atom. A method of copolymerization, a method of producing a block copolymer (E) using a coupling agent having a sulfur atom, and a method of introducing a sulfur atom by modification (chemical conversion) can be mentioned. Polymerization initiators having sulfur atoms include, for example, commercially available sulfur-based RAFT initiators.
Also, a method of obtaining a polymer using a chain transfer agent having a mercapto group such as mercaptohexanol can be used. Furthermore, a method of directly introducing a sulfur atom such as a mercapto group by adding 1,2-ethanedithiol or the like to the block copolymer (E) obtained after polymerization can also be mentioned.

[Method for producing block copolymer (E)]
An example of the method for producing the block copolymer (E) of the present embodiment will be described below, but the method is not limited to this.

The production method of the block copolymer (E) is not particularly limited, but a production method by radical polymerization or ionic polymerization is suitable. Ionic polymerization includes anionic polymerization and cationic polymerization. Although the type of radical polymerization is not particularly limited, living radical polymerization is preferred. Moreover, after obtaining a reactive terminal diblock structure, a block copolymer can also be obtained using a coupling agent.

Examples of anionic polymerization include a method in which an organic rare earth metal complex or an organic alkali metal compound is used as a polymerization initiator in the presence of an inorganic acid salt, and an organic alkali metal compound as a polymerization initiator in the presence of an organic aluminum compound. There is a method of polymerizing using
Examples of living radical polymerization include polymerization/NMP method using nitroxide-based catalysts, atom transfer radical polymerization/ATRP method using transition metal complex-based catalysts, and reversible addition using reversible addition-fragmentation chain transfer agents. - Fragmentation chain transfer polymerization/RAFT method, polymerization using organic tellurium catalyst/TERP method, iodine transfer polymerization using iodine compound as catalyst/RCMP method (reversible coordination mediated polymerization) or RTCP method (reversible transfer catalyst polymerization) can be exemplified.

Another method includes a step of obtaining polymer block B and polymer block A by sequential polymerization in this order using any polymerization initiator having 2 to 6 polymerization initiation points [polymer block A - polymer block B] _q There is a method for producing a block copolymer represented by X.

Another method includes a step of sequentially polymerizing polymer block A, polymer block B, and polymer block A in this order starting from a polymerization initiator, polymer block A—polymer block B—polymer block. There is a method for producing a block copolymer represented by an A-type triblock structure.

Further, by sequentially polymerizing the polymer block B and the polymer block A in an arbitrary order, an AB type diblock structure is obtained, and if necessary, a reactive terminal is added to the molecular end of the AB type diblock structure. and performing a coupling reaction using any coupling agent having 3 to 6 linking units exhibiting reactivity with the reactive terminal [polymer block A-polymer block B] _q There is a method for producing a block copolymer represented by X.

Also, the block copolymer (E) may be a commercial product. A commercial example is an acrylic triblock copolymer made using living polymerization from Arkema. Specifically, SBM type represented by polystyrene-polybutadiene-polymethyl methacrylate, MAM type represented by polymethyl methacrylate-polybutyl acrylate-polymethyl methacrylate, and carboxylic acid modification treatment or hydrophilic group modification treatment MAMN type or MAMA type can be used. Another example of a commercial product is a block copolymer derived from methyl methacrylate and butyl acrylate from Kuraray.

In this implementation, the content of the block copolymer (E) is 8% by mass or more and 40% by mass or less with respect to the total solid content contained in the conductive composition. It is more preferably 10% by mass or more and 38% by mass or less, and even more preferably 15% by mass or more and 35% by mass or less. When the content of the block copolymer (E) is within the above range, it imparts sufficient flexibility to the conductive layer, effectively suppresses the occurrence of cracks in the conductive layer during elongation, and provides a sufficient amount of conductivity. By containing the conductive fine particles (F), a conductive layer having excellent conductivity can be obtained.

The block copolymer used for the block copolymer (E) may be used singly or in combination of two or more.

Moreover, you may use other binder resin together as a resin component other than a block copolymer (E) as needed. Resin components other than the block copolymer (E) are 50% by mass or less, more preferably 30% by mass or less, and still more preferably 10% by mass or less in the total resin components. is preferable from the viewpoint of

<Conductive fine particles (F)>
The conductive fine particles (F) exhibit conductivity when a plurality of conductive fine particles come into contact with each other in the conductive layer. Selectively used. The conductive fine particles used in this embodiment include metal fine particles, carbon fine particles, conductive oxide fine particles, and the like.
Examples of fine metal particles include single powders of metals such as gold, silver, copper, nickel, chromium, palladium, rhodium, ruthenium, indium, aluminum, tungsten, molbutene, and platinum, as well as copper-nickel alloys, silver-palladium alloys, Alloy powders such as copper-tin alloys, silver-copper alloys, copper-manganese alloys, and gold-coated powders obtained by coating the surface of the above-mentioned single metal powders or alloy powders with silver or the like can be mentioned. Carbon fine particles include carbon black, graphite, and carbon nanotubes. Examples of conductive oxide fine particles include silver oxide, indium oxide, tin oxide, zinc oxide, and ruthenium oxide.

In this embodiment, among others, it is preferable to include one or more kinds of conductive fine particles selected from the group consisting of silver powder, copper powder, silver-coated powder, copper alloy powder, conductive oxide powder, and carbon fine particles. By using these conductive fine particles (F), a conductive layer having excellent conductivity can be formed without sintering.

The shape of the conductive fine particles (F) is not particularly limited, and amorphous, aggregated, scale-like, microcrystalline, spherical, flake-like, wire-like and the like can be used as appropriate. Agglomerated, scale-like, flake-like, and wire-like are preferred from the viewpoint of maintaining conductivity during molding and from the viewpoint of adhesion of the conductive pattern to the base material.

The average particle size of the conductive fine particles (F) is not particularly limited, but is preferably 0.1 μm or more and 50 μm or less from the viewpoint of dispersibility in the conductive composition and conductivity when used as a conductive layer. .5 μm or more and 30 μm or less is more preferable.
In this embodiment, the average particle size of the conductive fine particles (F) is calculated as follows. Based on the laser diffraction/scattering method described in JISM8511 (2014), using a laser diffraction/scattering particle size distribution analyzer (manufactured by Nikkiso Co., Ltd.: Microtrac 9220FRA), a commercially available surfactant polyoxyethylene octylphenyl was used as a dispersant. An appropriate amount of conductive fine particles (F) was added to an aqueous solution containing 0.5% by volume of ether (Triton X-100 manufactured by Roche Diagnostics Co., Ltd.) and irradiated with 40 W ultrasonic waves for 180 seconds while stirring. Then I took measurements. The obtained median diameter (D50) was taken as the average particle diameter of the conductive fine particles (F).

In this implementation, the conductive fine particles (F) can be used singly or in combination of two or more. The content of the conductive fine particles (F) in the conductive composition of the present embodiment is 60% by mass or more and 95% by mass or less with respect to the total solid content contained in the conductive composition. Furthermore, from the viewpoint of conductivity and stretchability, the total amount of solids contained in the conductive composition is preferably 65% by mass or more and 90% by mass or less, and 70% by mass or more and 85% by mass or less. more preferred. If the content of the conductive fine particles (F) is at least the above lower limit, a conductive layer with excellent conductivity can be formed. Further, if the content of the conductive fine particles (F) is equal to or less than the above upper limit, the content of the block copolymer (E) can be increased, and film formability and adhesion to the elastic film are improved. In addition, flexibility and stretchability can be imparted to the conductive layer.

<Linked silver powder (f1)>
The conductive composition of the present invention contains, as conductive fine particles (F), chain-like silver powder (f1) having a tap density of 2.0 g/cm ³ or less. Here, the chain-like silver powder is a silver powder in which fine particles are aggregated to form aggregated particles, and has a granular or agglomerated shape. Specifically, agglomerated silver powder (reduced silver powder) and branched silver particles, that is, dendritic silver powder and the like can be used. Further, the chain-like silver powder (f1) is preferably chain-like silver powder in which fine particles of 1 μm or less are aggregated to form aggregated particles.

The tap density of the chain-like silver powder (f1) is more preferably 0.3 to 1.5 g/cm ³ and even more preferably 0.3 to 1.0 g/cm ³ . Although the detailed mechanism is not clear, when the tap density is 2.0 g/cm ³ or less, the volume of the silver powder increases and the number of contact points increases, so it is thought that electrical conduction is more likely to occur. As a result, an excellent resistance value can be obtained even if strong expansion and contraction is applied to the conductor. In this specification, the tap density was measured according to ISO3953, and the tap count was 1000 times.

The specific surface area of the chain-shaped silver powder (f1) measured by the BET method is preferably 1.0 to 5.0 m ² /g.

The chain-like silver powder (f1) preferably has an average particle size (D50) of 3 to 15 μm as measured by a laser analysis scattering particle size distribution measurement method.

The content of the chain-shaped silver powder (f1) is 20% by mass or more and less than 70% by mass with respect to the total solid content in the conductive composition. Within the above range, it is possible to achieve both a low resistance value and conductive stability during expansion and contraction. In particular, when the amount of the chain-shaped silver powder (f1) is less than 70% by mass with respect to the total solid content in the conductive composition, the printability (adhesion) to the stretchable film substrate is good. A good conductor can be obtained. The blending amount is preferably 30% by mass or more and less than 70% by mass, more preferably 40% by mass or more and less than 70% by mass, still more preferably 50% by mass or more and less than 70% by mass, and particularly preferably 50% by mass. It is more than mass % and below 65 mass %. Although the detailed mechanism of the above effect is not clear, it is speculated as follows. By adjusting the content of the chain-like silver powder (f1) to the above amount, the polymer block A and the polymer block B constituting the block copolymer (E) described above easily form a microphase-separated structure. As a result, the stretchability of the block copolymer (E) can be made excellent. Furthermore, the optimized self-organization of the microphase-separated structure (aggregation of segments) further improves the affinity between the block copolymer (E) and the chain-like silver powder (f1), and the conductive fine particles (F ) is thought to improve dispersibility. Thereby, an ideal conductive path design that can withstand expansion and contraction (elastic deformation) and a conductive composition excellent in printability (ideal dispersion design) can be produced.

The chain-like silver powder (f1) may be used alone or in combination of two or more.

<Flake-like silver powder (f2)>
The conductive composition of the present invention preferably further contains flaky silver powder (f2) as the conductive fine particles (F).
By using the flaky silver powder (f2) together with the chain-like silver powder (f1) described above, it is possible to achieve both a lower resistance value and electrical conductivity stability during expansion and contraction. In addition, it is possible to easily obtain a conductor having better printability (adhesion) to a stretchable film substrate.

Here, the flaky silver powder includes shapes such as flat, flaky, and scaly, and also includes shapes obtained by crushing three-dimensional silver powder such as spherical and lumpy in one direction. Specifically, it is preferable to include leaf-like silver powder whose thickness is independently 1/10 or less with respect to the length in the longitudinal direction of the flat portion and the length in the transverse direction of the flat portion. In the present invention, the lengths in the longitudinal direction of the flattened portion and in the transverse direction of the flattened portion of one silver powder of the flaky silver powder (f2) are preferably in the range of 1 μm to 100 μm independently, and the thickness is 0. Those in the range of 0.05 μm to 1 μm are more preferred.

The 50% particle size (D50) of the flaky silver powder (f2) measured by a laser diffraction method is preferably 1 μm to 20 μm, more preferably 3 μm to 15 μm. When the 50% particle diameter (D50) is 1 μm or more, it is easy to develop good conductivity, and when it is 20 μm or less, the thickness of the conductive layer does not become too thick, so it can be used as a stretchable conductive device. Good flexibility when used. Furthermore, by using flaky silver powder having a 50% particle size (D50) larger than the thickness of the conductive layer, the stretch conductivity can be further improved. The 50% particle diameter (D50) in this specification is a value measured using water as a solvent by a laser diffraction method using a particle size distribution meter ("SALD-3100" manufactured by Shimadzu Corporation).

The bulk density of the flaky silver powder (f2) is preferably 0.2-0.7 g/cm ³ , more preferably 0.4-0.6 g/cm ³ . When the bulk density is in the above range, it is easy to develop good conductivity. The bulk density of the present invention is a value measured by a method according to JIS-Z2504.

The flaky silver powder (f2) preferably has a 50% particle diameter (D50) of 1 μm to 20 μm and a bulk density of 0.2 g/cm ³ to 0.7 g/cm ³ as described above. The flaky silver powder expresses conductivity by overlapping in the conductive layer, but by having the above particle size and bulk density, the overlapping in the conductive layer becomes good, and when used as a stretchable electronic device. Excellent flexibility.

The flaky silver powder in the conductive layer does not necessarily have to be oriented, but by orienting the flat part of the flaky silver powder roughly parallel to the coating surface, the number of contact points between the flaky silver powder increases and the conductivity improves. do. On the other hand, when the flaky silver powder is irregularly oriented, the number of contact points between the flaky silver powders decreases, and the amount of the flaky silver powder needs to be increased to achieve the desired conductive properties.

The flaky silver powder of the present invention includes, for example, common flake shapes, scale shapes, and plate shapes.

The flaky silver powder preferably has a specific surface area of 0.3 to 4.0 m ² /g and a tap density of 1 to 4 g/cm ³ .

The flaky silver powder may be used alone or in combination of two or more. The content of the flaky silver powder is preferably 1 to 75% by mass, more preferably 5 to 60% by mass, based on the total solid content in the conductive composition. .

In addition, the conductive composition of the present invention may contain other conductive fine particles within a range that does not impair the effects of the present invention.

<Crosslinking agent (D)>
The conductive composition of the present invention may further contain other components as necessary. In particular, when the block copolymer (E) contained in the conductive composition of the present invention has the above-described reactive functional group, it is preferable that the cross-linking agent (D) is further included.

A cross-linking agent (D) is used to cross-link the block copolymer (E). The cross-linking reaction between the block copolymer (E) and the cross-linking agent (D) can be accelerated by heat and/or irradiation with active energy rays such as ultraviolet rays. Examples of active energy rays include ultraviolet rays, electron beams, α rays, β rays, and γ rays. A part of the cross-linking agent and the block copolymer may already be cross-linked at the stage of the conductive composition.

By building a crosslinked structure while maintaining stretchability using a resin composition in which a crosslinker (D) and a block copolymer (E) are used in combination, cohesive force is promoted to increase stretchability, and solvent resistance is improved. It is possible to provide a member having excellent elasticity and stretch conductivity.

When the block copolymer (E) has the above-described reactive functional group, the cross-linking agent (D) preferably has a functional group capable of cross-linking with the reactive functional group. The type of cross-linking agent may vary depending on the type of functional group of block copolymer (E). When the functional group is a hydroxyl group or an amino group, the cross-linking agent is preferably an isocyanate compound, an epoxy compound, or a metal chelate compound. When the functional group is an epoxy group or an oxetane group, the cross-linking agent is preferably an amine-based compound. When the functional group is an isocyanate group or a blocked isocyanate group, the cross-linking agent is preferably a hydroxyl group-based compound. When the group is a vinyl group, a furyl group, or an acetoacetyl group, the cross-linking agent is preferably a polyfunctional acrylate-based monomer compound, and when the functional group is a hydrolyzable silyl group, the cross-linking agent is a silane coupling agent. Compounds are preferred. When the functional group is a nitrile group, the cross-linking agent is preferably a phenolic resin compound.

Compounds having two or more isocyanate groups are suitable as the isocyanate compound, and isocyanate monomers such as aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, and alicyclic polyisocyanates, and burettes and nurates. and adducts can be exemplified.

Specific examples of the isocyanate compound include 1,3-phenylene diisocyanate, 4,4'-diphenyldiisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6 - tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanatotoluene, 1,3,5-triisocyanatobenzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4', Aromatic polyisocyanates such as 4″-triphenylmethane triisocyanate;
trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (also known as HMDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4, Aliphatic polyisocyanates such as 4-trimethylhexamethylene diisocyanate;
ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate , araliphatic polyisocyanates such as 1,3-tetramethylxylylene diisocyanate;
3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (also known as IPDI, isophorone diisocyanate), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4 -cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate, 4,4'-methylenebis(cyclohexylisocyanate), 1,4-bis(isocyanatomethyl)cyclohexane and other alicyclic polyisocyanates.

The burette body refers to a self-condensed product having a burette bond formed by self-condensation of an isocyanate monomer. Specifically, for example, a burette form of hexamethylene diisocyanate can be mentioned.

The nurate compound is a trimer of an isocyanate monomer, and examples thereof include a trimer of hexamethylene diisocyanate, a trimer of isophorone diisocyanate, and a trimer of tolylene diisocyanate.

The adduct refers to a bifunctional or higher isocyanate compound obtained by reacting an isocyanate monomer and a bifunctional or higher low-molecular weight active hydrogen-containing compound. For example, a compound obtained by reacting trimethylolpropane and hexamethylene diisocyanate, trimethylolpropane and A compound obtained by reacting tolylene diisocyanate, a compound obtained by reacting trimethylolpropane and xylylene diisocyanate, a compound obtained by reacting trimethylolpropane and isophorone diisocyanate, and a reaction of 1,6-hexanediol and hexamethylene diisocyanate. compounds that have been prepared.

The epoxy compound is preferably a compound having two or more epoxy groups. A compound having a glycidyl group, a bisphenol type epoxy resin, and a novolac type epoxy resin can be exemplified.
Specific examples include bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol A/bisphenol F copolymer type epoxy resin;
novolac epoxy resins such as cresol novolak epoxy resins and phenol novolak epoxy resins;
ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidylaniline, N,N,N', N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidylaminophenylmethane, triglycidylaminophenol , biphenyldiglycidyl ether, triglycidyl isocyanurate, polyglycidyl (meth)acrylate, copolymers of glycidyl (meth)acrylate and a vinyl monomer copolymerizable therewith, and other compounds having a glycidyl group. .

Examples of the metal chelate compounds include coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium and acetylacetone or ethyl acetoacetate. be done. Specific examples include aluminum ethylacetoacetate/diisopropylate, aluminum trisacetylacetonate, aluminum bisethylacetoacetate/monoacetylacetonate, and aluminum alkylacetoacetate/diisopropylate.

Examples of the polyfunctional acrylate monomer compound include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, meth)acrylate, neopentyl glycol adipate di(meth)acrylate, neopentyl glycol hydroxypivalate di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphorus Acid di(meth)acrylate, di(acryloxyethyl)isocyanurate, allylated cyclohexyl di(meth)acrylate, ethoxylated bisphenol A diacrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene Bifunctional type such as; Trifunctional types such as tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, ε-caprolactone-modified tris-(2-(meth)acryloxyethyl)isocyanurate; diglycerin tetra(meth)acrylate, pentaerythritol tetra Tetrafunctional type such as (meth)acrylate; Pentafunctional type such as propionic acid-modified dipentaerythritol penta(meth)acrylate; Hexafunctional type such as dipentaerythritol hexa(meth)acrylate and caprolactone-modified dipentaerythritol hexa(meth)acrylate type, etc.
The polyfunctional acrylate-based monomer compound can form crosslinks through an enethiol reaction with the reactive functional groups of the block copolymer (E).

Among the cross-linking agents, isocyanate compounds and epoxy compounds are more preferable from the viewpoint of storage stability and curability.

The molar ratio of the reactive functional group of the block copolymer (E) to the functional group (crosslinking agent) in the crosslinker (reactive functional group (block copolymer (E))/functional group ( The cross-linking agent)) is preferably from 0.01 to 10.0, more preferably from 0.5 to 2.0, from the viewpoint of promoting the formation of a microphase-separated structure.

For example, 0.01 to 50.0 parts by mass of the cross-linking agent can be contained with respect to 100 parts by mass of the block copolymer (E). It is more preferably 0.1 to 10.0 parts by mass, still more preferably 0.5 to 1.5 parts by mass, per 100 parts by mass of the block copolymer.

From the viewpoint of more effectively drawing out the stretchability of the block copolymer (E) and the stretchability of the stretchable conductive material, the cross-linking agent is a polymer block A in which a reactive functional group may be present, or a polymer block A higher affinity with B is more preferable. For example, affinity (compatibility) can be selected with reference to solubility parameter values.

When adding a cross-linking agent to the conductive composition of the present invention, a cross-linking accelerator may be added to promote the cross-linking reaction. Examples of cross-linking accelerators include organic tin-based catalysts, inorganic metal catalysts, inorganic tin compounds, acid-based catalysts, organic base-based catalysts, acid anhydride-based catalysts, and the like.

<Solvent>
The solvent that the conductive composition may contain is not particularly limited, and examples thereof include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, xylene, acetone, hexane, methyl ethyl ketone, cyclohexanone, propylene glycol monomethyl ether acetate, and ethylene glycol. monobutyl ether acetate, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol monoethyl ether acetate, tetraethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol dimethyl ether, diacetone alcohol, cyclohexanone and isophorone.
These solvents may be used singly or in combination of two or more. Among them, in order to adapt the conductive paste to screen printing, it is preferable to use a solvent with a boiling point of 180 ° C. or higher and 270 ° C. or lower in order to prevent the paste from drying inside the mesh of the printing plate and blocking the mesh. .

<Other ingredients>
If necessary, the conductive composition of the present invention further includes the above-described crosslinking agent (D), dispersant, friction improver, infrared absorber, ultraviolet absorber, aromatic agent, antioxidant, organic pigment, inorganic Other ingredients such as pigments, antifoaming agents, silane coupling agents, plasticizers, flame retardants, and humectants may also be contained.

<Conductor and Conductive Layer>
By printing the conductive composition of the present invention on an elastic film by screen printing or the like, a conductor having excellent conductivity can be formed. In addition, a stretchable conductive material having a conductive layer made of the conductor can be easily produced.

The method of forming the conductive layer is not particularly limited, but in this embodiment, screen printing, pad printing, stencil printing, screen offset printing, dispenser printing, gravure offset printing, reverse offset printing, and microcontact printing are used. It is preferably formed by a method, and more preferably formed by a screen printing method.
In the screen printing method, it is preferable to use a fine mesh screen, particularly preferably a fine mesh screen of about 300 to 650 mesh, in order to cope with the high definition of the conductive circuit pattern. The open area of the screen at this time is preferably about 20 to 50%. The screen line diameter is preferably about 10-70 μm.
Types of screen plates include polyester screens, combination screens, metal screens, nylon screens, and the like. Also, when printing a high-viscosity paste, a high-tensile stainless steel screen can be used.
Screen printing squeegees can be round, rectangular, or square in shape, and abrasive squeegees can also be used to reduce the angle of attack (the angle between the plate and the squeegee during printing). As other printing conditions, conventionally known conditions may be appropriately designed.

The method of curing the conductive composition is not particularly limited, but for example, the conductive composition of the present invention can be cured by heating and drying after printing by screen printing.
Moreover, when the conductive composition contains a cross-linking agent (D), it is further cured by a cross-linking reaction by heating. When the cross-linking agent is not contained, the solvent is sufficiently volatilized, and when the cross-linking agent is contained, the heating temperature is 80 to 230 ° C. and the heating time is for sufficient volatilization of the solvent and cross-linking reaction. 10 to 120 minutes is preferable. Thereby, a patterned conductive layer can be obtained. If necessary, the patterned conductive layer may be provided with an insulating layer so as to cover the conductive pattern. The insulating layer is not particularly limited, and a known insulating layer can be applied.

The film thickness of the conductive layer may be appropriately adjusted according to the desired conductivity and the like, and is not particularly limited.

<Stretchable conductive material>
In addition, according to the conductive composition, the decrease in conductivity due to repeated expansion and contraction is suppressed, the printability of the conductive material on the stretchable base material is improved, and the conductive layer made of the conductive material and the conductive layer described later It is possible to manufacture a stretchable conductive material that has excellent adhesion to a stretchable film substrate.
Then, the stretchable conductive material produced using the conductive composition suppresses a decrease in conductivity even when used on a substrate surface that can follow an uneven curved surface portion or a movable portion. .

[Elastic base material]
The stretchable film substrates used in the present practice are composed of natural or synthetic materials that are resistant to breakage or cracking during stretching.
The stretchable film substrate is preferably a substrate having a Young's modulus of less than 100 MPa at 23°C. Young's modulus at 23° C. is preferably less than 50 MPa, more preferably less than 10 MPa, and even more preferably less than 1 MPa. Furthermore, the elastic film substrate is preferably a substrate having a tensile elongation at break of 150% or more at 23°C. The tensile elongation at break at 23°C is preferably 200% or more, more preferably 400% or more. When the elastic film substrate has a Young's modulus of less than 100 MPa and a tensile elongation at break of 150% or more at 23° C., it is less likely to break or crack during stretching, and can be used as a substrate suitable for a stretchable conductive material. It becomes possible.

Examples of stretchable film substrates include thermoplastic elastomers, plastics, fibers, non-woven fabrics, silicone rubbers, fluororubbers, nitrile rubbers, nitrile-butadiene rubbers, chlorosulfonated polyethylenes, polysulfide rubbers, acrylic rubbers, styrene rubbers, and styrene-butadiene. It can be selected from rubber, chloropyrene rubber, urethane rubber, butyl rubber, ethylene rubber, propylene rubber, ethylene propylene rubber, epoxy rubber, butadiene rubber, natural rubber, and isoprene rubber. good. Further, the shape of the film substrate may be planar such as plate-like or film-like, curved surface shape or complicated shape.

Examples of the thermoplastic elastomer include polyurethane-based, polyester-based, polyolefin-based, polyamide-based, polyimide-based, polyester-based, vinyl chloride-based, styrene-based block polymers, and acrylic block polymers.

Examples of the plastic include polyolefins such as polyvinyl alcohol, triacetyl cellulose, polypropylene, polyethylene, polycycloolefin and ethylene-vinyl acetate copolymer; polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate; polycarbonate and polynorbornene. , polyarylates, polyacrylics, polyphenylene sulfides, polystyrenes, epoxies, polyamides, and polyimides.

From the standpoint of stretchability, the stretchable film substrate is particularly preferably made of polyurethane, silicone rubber, ethylenepropylene rubber, styrene rubber, acrylic rubber, or epoxy rubber.

The thickness of the elastic film substrate is not particularly limited, but can be, for example, 1 to 500 μm. Also, it may be 10 to 100 μm, or 20 to 50 μm. When the thickness of the elastic film substrate is within the above range, the film is excellent in terms of windability and workability. On the other hand, if the elastic film substrate is thin, the strength tends to be insufficient. On the other hand, if the film substrate is too thick, the flexibility is poor, and there is a possibility that the film substrate will not follow the shape of the adherend.

Further, if necessary, for the purpose of improving the printability of the conductive composition, an anchor coat layer may be provided on the stretchable film substrate, and the conductive composition may be printed on the anchor coat layer. The anchor coat layer is not particularly limited as long as it has good adhesion to the film base material, further adhesion to the conductive composition, and follows the elastic film during molding. Inorganic fillers such as fillers and metal oxides may be added as necessary. The method of providing the anchor coat layer is not particularly limited, and it can be obtained by coating, drying and curing by a conventionally known coating method.

Further, if necessary, in order to prevent scratches on the surface of the molded product, a hard coat layer may be provided on the elastic film substrate, and the conductive composition and, if necessary, a decorative layer may be printed on the opposite surface. good. The hard coat layer is not particularly limited as long as it has good adhesion to the elastic film base material and surface hardness and follows the elastic film during molding. Inorganic fillers such as solids may also be added as needed. The method of providing the hard coat layer is not particularly limited, and it can be obtained by coating, drying and curing by a conventionally known coating method.

The stretchable conductive material may be laminated on a support and used as a laminate. The support is not particularly limited, but is preferably a stretchable material in order to take advantage of the stretchability of the stretchable film substrate. Specific examples include stretchable plastic films and stretchable fibers. The elastic fibers may be textile fabrics. Alternatively, a concave portion may be provided in the support and the elastic conductor may be embedded in this concave portion.

The stretchable conductive material and the support may be joined using the adhesiveness of the stretchable conductive material, or may be joined by lamination. Moreover, it is also possible to join via an adhesive layer or an easy-adhesive layer.

The stretchable conductive material thus obtained may itself be a product or may be used as a member. A stretchable conductive material is suitable for, for example, stretchable wiring and stretchable electrodes. In addition, the stretchable conductive material can be used as a film such as a stretchable electromagnetic wave shield layer and a stretchable heat dissipation layer. It can also be used as a conductive molded article having a desired shape.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these. In the following description, "parts" means "parts by mass" and "%" means "% by mass" unless otherwise specified. Values other than the solvent are non-volatile content conversion values.

[Measurement of Weight Average Molecular Weight (Mw), Number Average Molecular Weight (Mn) and Mw/Mn]
GPC (trade name: GPCV-2000, manufactured by Nippon Waters Co., Ltd., column: TSKgel, α-3000, mobile phase: 10 mM triethylamine/dimethylformamide solution) was used, and polystyrene (molecular weight: 427,000, 190,000, 96) was used as a standard substance. , 400, 37,400, 10,200, 2,630, 440, 92) was used to prepare a calibration curve, and the weight average molecular weight (Mw) and number average molecular weight (Mn) were measured. The polydispersity index (PDI=Mw/Mn) was calculated from this measured value.

[Measurement of glass transition point]
The glass transition point is measured in accordance with JIS K 7121 (2012) Plastic transition temperature measurement method, and the glass transition point is measured at the temperature determined by the extrapolated glass transition start temperature (Tig) described in JIS 9.3. asked. A differential scanning calorimeter (DSC Q2000, manufactured by TA Instruments) was used for the measurement.
By the above method, the Tg of <polymer block A> _Total , the Tg of polymer block B in the case of a triblock structure, and the Tg of [polymer block (B)] _q X in the case of a star block structure are Desired.

(Production example of block copolymer (E))
The abbreviations of the raw materials of the block copolymer (E) are as follows.
(monomer)
MMA: methyl methacrylate nBA: n-butyl acrylate 2EHA: 2-ethylhexyl acrylate St: styrene HEMA: 2-hydroxyethyl methacrylate MOI: 2-isocyanatoethyl methacrylate MAA: methacrylic acid

(Polymerization initiator)
Synthesis 1: Ethyl-2-methyl-2-n-butylteranyl-propionate (TERP polymerization initiator)
BM1448: 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanesanmethyl (manufactured by BORON MOLECULAR) (for RAFT polymerization)
CP-I: 2-iodo-2-methylpropionitrile (manufactured by Tokyo Chemical Industry Co., Ltd.) (for RCMP polymerization)
2f-BiB: Ethylene bis(2-bromoisobutylate) (manufactured by Aldrich, No. 723177) (for ATRP polymerization)
3f-BiB: 1,1,1-Tris (2-bromoisobutyloxymethyl) ethane (manufactured by Aldrich, No. 723185)
AIBN: 2,2'-azobis(isobutyronitrile) (manufactured by Wako Pure Chemical Industries, Ltd.)
V65: 2,2′-azobis(2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd.)

(Synthesis of TERP polymerization initiator)
Synthesis 1: (Ethyl-2-methyl-2-n-butylteranyl-propionate)
Synthesized according to the method disclosed in WO2007/119884. Specifically, 6.38 g (50 mmol) of tellurium metal [manufactured by Aldrich, trade name: Tellurium (-40 mesh)] was suspended in 50 mL of THF. .4 mL (55 mmol) was slowly added dropwise (10 minutes) at room temperature. The reaction solution was stirred until the tellurium metal completely disappeared (20 minutes). To this reaction solution, 10.7 g (55 mmol) of ethyl-2-bromo-isobutyrate was added at room temperature and stirred for 2 hours. After completion of the reaction, the solvent was concentrated under reduced pressure, followed by distillation under reduced pressure to obtain 7.67 g (yield 46.5%) of the compound of Synthesis 1 as a yellow oil. In addition, formation of the desired product was confirmed by 1H-NMR analysis.

<Resin Production Example 1: Synthesis of block resin (E1)>
A block copolymer used for the block copolymer (E) was synthesized by the TERP method. Specifically, 0.25 g of ethyl-2-methyl-2-n-butylteranyl-propionate (Synthesis 1), 0.01 g of AIBN, and 70.3 g of MMA were added to 200 g of methyl ethyl ketone solvent in a glove box that was purged with argon. C. for 6 hours to obtain a prepolymer. The conversion of MMA calculated from 1H-NMR was 99.5% or more. Then, 450.0 g of nBA was added to the total prepolymer solution and reacted at 50° C. for 40 hours. The conversion rate of the second stage monomer nBA calculated from 1H-NMR was 99.5% or more. Furthermore, 70.3 g of MMA was added to the total amount of the prepolymer solution and reacted at 50° C. for 6 hours. The conversion of the third-stage monomer MMA calculated from 1H-NMR was 99.5% or more. Thereafter, the mixture was cooled to room temperature, filtered, washed and dried to obtain a block copolymer having an ABA triblock structure with the initiator residue X at the chain end. Table 1 shows the physical property values of the block copolymer according to Production Example E1 (the same applies to the following production examples of block copolymer (E)).

<Resin Production Example 2: Synthesis of block resin (E2)>
A block copolymer used for the block copolymer (E) was synthesized by the ATRP method. Specifically, 1.0 g of copper (I) bromide, 0.4 g of 3f-BiB, 257.1 g of nBA and 192.9 g of 2EHA were added to 400 g of methyl ethyl ketone solvent in a 2,000 mL flask equipped with a nitrogen gas inlet tube and a stirrer. and 85° C. for 8 hours to obtain a prepolymer. The conversion rates of nBA and 2EHA calculated from 1H-NMR were both 100%. Then, 99.5 g of MMA and 99.8 g of St were added to the total prepolymer solution and reacted at 85° C. for 10 hours. The conversion rates of the second-stage monomers MMA and St calculated from 1H-NMR were both 100%. Then, it is cooled to room temperature, filtered, washed and dried to obtain a block copolymer having a three-branched [AB] ₃ X star block structure in which the initiator residue X is at the branch center of the polymer molecule. Obtained.

<Resin Production Example 3: Synthesis of block resin (E3)>
A block copolymer used for the block copolymer (E) was synthesized by the RAFT method. Specifically, in a 2,000 mL flask equipped with a nitrogen gas inlet tube and a stirrer, 9.1 g of BM1448 (RAFT agent), 0.2 g of AIBN, and 140.6 g of MMA were added in 200 g of a methyl ethyl ketone solvent in an environment of 75 ° C. A prepolymer was obtained by reacting for 6 hours. The conversion of MMA calculated from 1H-NMR was 99.5% or more. 0.3 g of AIBN, 438.3 g of nBA and 11.7 g of MAA were then added to the total prepolymer solution and allowed to react at 75° C. for 10 hours. Both conversion rates of the second-stage monomers nBA and MAA calculated from 1H-NMR were 100%. Thereafter, the mixture was cooled to room temperature, filtered, washed and dried to obtain a block copolymer having an AB diblock structure in which the initiator residue X had a carboxyl group at the chain end.

<Resin Production Example 4: Synthesis of block resin (E4)>
A block copolymer used for the block copolymer (E) was synthesized by the RCMP method. Specifically, 2.15 g of CP-I, 0.001 g of iodine, 15.0 g of sodium iodide, 8.6 g of MMA, 42.9 of St, and 5.7 g of HEMA were placed in a 2,000 mL flask equipped with a nitrogen gas inlet tube and a stirrer. was reacted in 200 g of methyl ethyl ketone solvent at 75° C. for 6 hours to obtain a prepolymer. The conversion rates of MMA, St and HEMA calculated from 1H-NMR were all 99.5% or more.
Then, 450.0 g of nBA was added to the total prepolymer solution and reacted at 80° C. for 40 hours. The conversion rate of the second stage monomer nBA calculated from 1H-NMR was 99.5% or more. Further, 8.6 g of MMA, 42.9 of St and 5.7 g of HEMA were added to the total amount of the prepolymer solution and reacted at 75° C. for 6 hours. The conversion rates of the third-stage monomers MMA, St, and HEMA calculated from 1H-NMR were all 99.5% or more. Thereafter, the mixture was cooled to room temperature, filtered, washed and dried to obtain a block copolymer having an ABA triblock structure having an initiator residue X at the chain end and a hydroxyl group.

<Resin Production Example 5: Synthesis of block resin (E5)>
A block copolymer used for the block copolymer (E) was synthesized by the RAFT method. Specifically, in a 2,000 mL flask equipped with a nitrogen gas inlet tube and a stirrer, 1.2 g of BM1448 (RAFT agent), 0.2 g of AIBN, and 193.3 g of MMA were added in 200 g of a methyl ethyl ketone solvent in an environment of 75°C. A prepolymer was obtained by reacting for 6 hours. The conversion of MMA calculated from 1H-NMR was 99.5% or more. Then 0.3 g of AIBN, 430.7 g of nBA and 19.3 g of MOI were added to the total prepolymer solution and allowed to react at 75° C. for 10 hours. Both conversion rates of the second-stage monomer nBA and MOI calculated from 1H-NMR were 100%. After cooling to 50° C., 9.6 g of cysteamine and 100.0 g of methyl isobutyl ketone (boiling point: 116° C.) were added and reacted at 50° C. for ¹ hour. Confirmed disappearance. It was confirmed by 1H-NMR analysis, IR analysis, and mercaptan titration analysis that isocyanate groups were converted to mercapto groups. Thereafter, the mixture was cooled to room temperature, filtered, washed and dried to obtain a block copolymer having an AB diblock structure having an initiator residue X at the chain end and a mercapto group.

<Resin Production Example 6: Synthesis of block resin (E6)>
A block copolymer used for the block copolymer (E) was synthesized by the RAFT method. Specifically, in a 2,000 mL flask equipped with a nitrogen gas inlet tube and a stirrer, 0.8 g of BM1448 (RAFT agent), 0.2 g of AIBN, 65.7 g of MMA, and 9.0 g of MOI were added in 100 g of methyl ethyl ketone solvent at 75°C. The reaction was carried out for 6 hours under the environment of , to obtain a prepolymer. Both conversion rates of MMA and MOI calculated from 1H-NMR were 99.5% or more. Then, 0.3 g of AIBN and 450.0 g of nBA were added to the total prepolymer solution and allowed to react at 75° C. for 12 hours. The conversion of the second-stage monomer nBA calculated from 1H-NMR was 100%. Furthermore, 0.2 g of AIBN, 65.7 g of MMA, and 9.0 g of MOI were added to the total amount of the prepolymer solution and reacted at 75° C. for 6 hours. Both conversion rates of the third-stage monomer MMA and MOI calculated from 1H-NMR were 99.5% or more. After cooling to 50° C., 16.4 g of 1,4-bis(aminomethyl)cyclohexane and 100.0 g of methyl isobutyl ketone (boiling point: 116° C.) were added, reacted at 50° C. for 1 hour, and isocyanate was detected by IR. The disappearance of the peak at 2270 cm ⁻¹ based on the base was confirmed. It was confirmed by 1H-NMR analysis, IR analysis, and amine value measurement that the isocyanate group was converted to an amino group. Thereafter, the mixture was cooled to room temperature, filtered, washed and dried to obtain a block copolymer having an ABA triblock structure having an initiator residue X at the chain end and an amino group.

<Resin Production Example 7: Synthesis of block resin (E7)>
A block copolymer used for the block copolymer (E) was synthesized by the RCMP method. Specifically, in a 2,000 mL flask equipped with a nitrogen gas inlet tube and a stirrer, 2.15 g of CP-I, 0.001 g of iodine, 15.0 g of sodium iodide, and 450.0 g of nBA were mixed in 200 g of methyl ethyl ketone solvent, and C. for 24 hours to obtain a prepolymer. All nBA conversions calculated from 1H-NMR were 99.5% or more.
Then, 192.8 g of MMA was added to the total prepolymer solution and reacted at 70° C. for 8 hours. The conversion of the second-stage monomer MMA calculated from 1H-NMR was 99.5% or more. Thereafter, the mixture was cooled to room temperature, filtered, washed and dried to obtain a block copolymer having an AB diblock structure having the initiator residue X at the chain end.

<Resin Production Example 8: Synthesis of block resin (E8)>
A block copolymer used for the block copolymer (E) was synthesized by the RAFT method. Specifically, in the same manner as in Resin Production Example E6, polymerization was carried out by the RAFT method under the conditions shown in Table 1 with the charging ratio of the monomers, etc., and the ABA triblock structure having the initiator residue X at the chain end. A block copolymer was obtained.

<Block Resin (E9)>
LA2330 manufactured by Kuraray Co., Ltd. was used as a block copolymer used for the block copolymer (E).

(Production example of resin (E′) for comparative example)
<Resin Production Example 10: Synthesis of Resin (E'10)>
A block copolymer was synthesized for comparison with block copolymer (E). Specifically, in the same manner as in Resin Production Example E2, the polymerization was carried out by the ATRP method under the conditions shown in Table 1, such as the charging ratio of the monomers, and the ABA triblock structure having the initiator residue X at the chain end. A block copolymer was obtained.

<Resin Production Example 11: Synthesis of resin (E'11)>
A block copolymer was synthesized for comparison with block copolymer (E). Specifically, in the same manner as in Resin Production Example E1, polymerization was carried out by the TERP method under the conditions shown in Table 1 with the charging ratio of the monomers, etc., and the ABA triblock structure having the initiator residue X at the chain end. A block copolymer was obtained.

<Resin Production Example 12: Synthesis of resin (E'12)>
A random copolymer was synthesized for comparison with the block copolymer (E). Specifically, by the same RCMP method as in Resin Production Example E4, random polymerization was performed under the conditions shown in Table 1 with the charging ratio of the monomers, etc., to obtain a random copolymer with a random structure in which the initiator residue X is at the chain end. got

<Resin Production Example 13: Synthesis of resin (E'13)>
A urethane resin was synthesized for comparison with the block copolymer (E). Specifically, 783.0 g of polytetramethylene ether glycol (molecular weight: 1000) and 200.0 g of IPDI (isophorone diisocyanate) were charged into a 2,000 mL flask equipped with a nitrogen gas inlet tube and a stirrer, and the temperature was gradually raised. and reacted at 90° C. for 6 hours. After that, it was cooled to room temperature, filtered, washed and dried to obtain a urethane resin for comparison.

<Resin (E'14)>
Vylon (registered trademark) 290 manufactured by Toyobo Co., Ltd. was used as a polyester resin for comparison with the block copolymer (E).

(Manufacture of conductive composition and stretchable conductive material)
The following materials were used as the conductive fine particles, solvent, cross-linking agent, and elastic film substrate.
<Conductive fine particles (F)>
(Linked silver powder (f1))
・ f1-1 (tap density 0.7 g/cm ³ , average particle size 10 μm
・f1-2 (tap density 1.3 g/cm ³ , average particle size 4.2 μm)
(Flake-like silver powder (f2))
・f2-2 (tap density 3.3 g/cm ³ , average particle size 3.5 μm)
・f2-2 (tap density 1.1 g/cm ³ , average particle size 5.2 μm)
(Other conductive fine particles)
・Silver-coated copper powder, silver coating amount 10%, average particle size 2 μm
・Needle-shaped conductive tin oxide powder, average particle size 1 μm
・Expanded graphite, average particle size 15 μm
<Solvent>
・Diethylene glycol monobutyl ether, boiling point 231°C
<Crosslinking agents (D1), (D2)>
- Crosslinking agent (D1):
Blocked isocyanate solution from Baxeneden Chemicals, Trixe
neBI7982, containing 3 blocked isocyanate groups per molecule (functionality value 195 mgKOH/g), non-volatile content 70% (solvent (C17): 2-methoxypropanol)
- Crosslinking agent (D2):
Glycidylamine manufactured by Nippon Kayaku Co., Ltd., GOT, containing two epoxy groups in one molecule (functional group value 4
15 mg KOH / g), non-volatile content 100%
<Stretchable film substrate>
・Polyurethane film (TPU):
ES85 manufactured by Okura Kogyo Co., Ltd., thickness 100 μm, tensile elongation at break 600%, Young's modulus 0.8 MPa (23° C.) was used.

<Production of conductive composition (K1)>
[Example 1]
20.0 parts of block copolymer (E1) is dissolved in 30.0 parts of diethylene glycol monobutyl ether, 60.0 parts of conductive fine particles (f1) and 20.0 parts of silver-coated copper are stirred and mixed, and a three-roll mill ( Kodaira Seisakusho Co., Ltd.) to obtain a conductive composition for a stretchable conductive material (K1).

<Production of conductive compositions (K2) to (K15)>
[Example 2-15]
In Example 1, the types and blending amounts of the resin, solvent, and conductive fine particles were changed as shown in Table 2, and if necessary, a cross-linking agent was further added. Chemical compositions (K2) to (K15) were obtained. In addition, all the numerical values of each material in Table 2 are parts by mass.

<Production of conductive compositions (L1) to (L9)>
[Comparative Example 1-9]
Comparative conductive compositions (L1) to (L9) were obtained in the same manner as in Example 1, except that the types and amounts of the resin, solvent, and conductive fine particles were changed as shown in Table 3. In addition, all the numerical values of each material in Table 3 are parts by mass.

<Production of stretchable conductive material>
[Example 16]
Subsequently, the conductive composition (K1) produced in Example 1 was printed on the polyurethane film (TPU) by a screen printer (Minomat SR5575 semi-automatic screen printer manufactured by Minoscreen Co., Ltd.). Next, by heating in a hot air drying oven at 100° C. for 30 minutes, a conductive layer having a rectangular solid shape with a width of 20 mm, a length of 60 mm, and a thickness of 10 μm and a linear pattern with a line width of 3 mm, a length of 60 mm, and a thickness of 10 μm is provided. A stretchable conductive material was obtained.

[Examples 17-30, Comparative Examples 10-18]
A stretchable conductive material was obtained in the same manner as in Example 16, except that the conductive composition used was changed to that shown in Table 4.

<Evaluation>
(conductivity | initial volume resistivity)
The volume resistivity of the stretchable conductive material according to each example and comparative example was measured. Specifically, a square solid stretchable conductive material having a width of 20 mm, a length of 60 mm, and a thickness of 10 μm, which was produced in the above examples and comparative examples, was used as a test piece. Using a surface resistance measuring instrument (product number: Loresta (registered trademark) AP MCP-T400, probe: ASP probe (4-point probe, manufactured by Mitsubishi Chemical Corporation), in an atmosphere at a temperature of 25 ° C. and a relative humidity of 50%, The volume resistivity of the test piece obtained according to JIS K7194 was measured.
The initial state was evaluated according to the following criteria.
+++: Less than 2.0×10 ⁻⁴ Ω·cm++: 2.0×10 ⁻⁴ Ω·cm or more, less than 9.9×10 ⁻³ Ω·cm+: 9.9×10 ⁻³ Ω·cm Above, less than 9.9×10 ⁻¹ Ω・cm NG: 9.9×10 ⁻¹ Ω・cm or more

(Damp heat resistance)
In addition, the volume resistivity of the stretchable conductive material was measured after 10 days in an environment of 85 ° C. and a relative humidity of 85% by the same method as described above, and the rate of change from the initial stage (change after the test) was as follows. was evaluated according to the criteria of
[Rate of change(%)]
= [(Volume resistivity of test piece before test) - (Volume resistivity of test piece after test)] ÷ [(Volume resistivity of test piece before test)]
+++: Rate of change is 20% or less ++: Rate of change is greater than 20% and is 50% or less +: Rate of change is greater than 50% and is 100% or less NG: Rate of change is greater than 100%

(Repeated expansion/contraction resistance | change in resistance value)
For the 20 mm × 60 mm size sample of the stretchable conductive material according to each example and comparative example, the end was fixed to a Tensilon tensile tester, 25 ° C., 50% relative humidity, at a speed of 4 mm / s Elongate to 50%, then hold for 2 s, then unload at a speed of 4 mm/s, hold for 2 s, repeat 1,000 times, and calculate the rate of change after 1,000 times by the following formula. bottom.
[Rate of change(%)]
= [(R1,000) - (R0)] ÷ [(R0)] x 100
Here, R1,000 is the resistance value immediately after stretching cycles repeated 1,000 times, and R0 is the resistance value using the same film before the start of measurement. Evaluation was made according to the following criteria.
+++: Rate of change is 20% or less ++: Rate of change is greater than 20% and is 50% or less +: Rate of change is greater than 50% and is 100% or less NG: Rate of change is greater than 100%

(Repeated expansion and contraction resistance | Appearance of conductive film)
In addition, the appearance of the stretchable conductive material after being shrunk 1000 times was compared with the state before the test and evaluated according to the following criteria.
+++: No change in appearance ++: Cracks such as cracks occur very slightly in appearance +: Cracks such as cracks occur in at least part of appearance NG: Cracks and cracks are obvious in appearance and the paint film is peeling off

(Printability evaluation)
A rectangular solid conductive layer having a width of 20 mm and a length of 60 mm formed on the stretchable conductive material according to each example and comparative example was cut with a cutter knife using a 1 mm interval cross-cut guide manufactured by Gardner. A grid of 10×10 squares was cut so as to penetrate the layer, and cellophane tape manufactured by Nichiban Co., Ltd. was adhered to remove trapped air and adhere well, and then peeled off vertically. The peeling degree of the coating film was evaluated as follows according to the ASTM-D3519 standard.
++: Evaluation 5B to 4B, good adhesion and excellent printability +: Evaluation is 5B to 4B, but the coating film undergoes cohesive failure, and a part of the coating film on the surface side is detached NG: Evaluation 3B Below, adhesion is poor and printability is poor.

Table 4 shows the results for each evaluation.

From the results of Examples 1 to 30 of the present invention, this implementation effectively suppresses the occurrence of cracks during elongation, resulting in excellent repeated stretching resistance, conductivity, moist heat resistance, and stretchable film substrates. A conductive composition and a stretchable conductive material with good printability were obtained. Due to the above properties, these are suitable for use in electronic devices.

Claims (10)

weight average molecular weight is 20,000 or more and 500,000 or less,
a block copolymer (E) mainly composed of structural units derived from an ethylenically unsaturated monomer;
A conductive composition containing conductive fine particles (F),
The content of the conductive fine particles (F) is 60 to 95% by mass with respect to the total solid content contained in the conductive composition, and among the conductive fine particles (F), chain-shaped silver powder (f1) is 20% by mass or more and less than 70% by mass with respect to the total solid content of the conductive composition,
A conductive composition, wherein the chain-like silver powder (f1) has a tap density of 2.0 g/cm ³ or less. 2. The conductive composition according to claim 1, further comprising flaky silver powder (f2), wherein the content of said flaky silver powder (f2) is 1 to 75% by mass with respect to the total solid content of said conductive composition. Conductive composition. 3. The structure of claim 1 or 2, wherein the structure of the block copolymer (E) is a triblock structure represented by the following formula (1) or a star block structure represented by the following formula (2). Conductive composition.
Formula (1)...polymer block A-polymer block B-polymer block A
Formula (2) [polymer block A-polymer block B] _q X
(In formula (1) above, the glass transition temperature of polymer block A is 20°C or higher, and the glass transition temperature of polymer block B is lower than 20°C. In formula (2) above, polymer block A The glass transition temperature of [polymer block B] _q X is 20° C. or higher, the glass transition temperature of [polymer block B] q is lower than 20° C., q is an integer of 2 or more and 6 or less, and X is an initiator residue and/or cup It is a ring agent residue or its derivative.) 4. The block copolymer (E) according to any one of claims 1 to 3, having one or more reactive functional groups selected from the group consisting of a mercapto group, a hydroxy group, an amino group, and a carboxy group. The electrically conductive composition described. 5. The conductive composition according to claim 4, further comprising a cross-linking agent (D) capable of cross-linking with said reactive functional group. The conductive composition according to any one of claims 1 to 5, wherein the block copolymer (E) contains a sulfur atom. A conductor containing the conductive composition according to any one of claims 1 to 6. A conductor obtained by forming a cured product of the conductive composition according to any one of claims 1 to 6 on a stretchable substrate. A stretchable conductive material comprising the conductor according to claim 7 or 8. An electronic device comprising the conductor according to claim 7 or 8 or the stretchable conductive material according to claim 9.