JP2012218185A - Conductive composite film, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive composite film, which is stable against a polar solvent such as alkylene carbonate with high solvent resistance, and exhibits low permeability of the polar solvents.SOLUTION: The conductive composite film is prepared by laminating a first conductive layer formed from a crystalline resin composition including crystalline resin and a first carbon-based conductive filler, and a second conductive layer formed from a cured product of a photo-curable composition including photo-curable resin and a second carbon-based conductive filler. The first and second carbon-based conductive fillers may be conductive carbon black. The crystalline resin may be polypropylene-based resin and/or polyamide-based resin. The photo-curable resin may include a polyfunctional vinyl compound which is at least trifunctional, and a monofunctional and/or bifunctional vinyl compound.

Description

  The present invention relates to a conductive composite film used for an electric double layer capacitor, a lithium ion battery, an electronic component, a semiconductor element, and the like, and a method for producing the same.

  In various fields where conductivity is required, such as electronic parts and semiconductor elements, a conductive film formed of a resin is used because of excellent moldability and flexibility. In particular, with the recent miniaturization and thinning of electronic components, a thin film is also required for the conductive film used.

  In Japanese Patent No. 4349793 (Patent Document 1), a low electric resistance layer having a volume resistance value in the thickness direction of 0.1 to 1.0 Ω · cm is provided on at least one outermost layer of a conductive base material layer. The volume resistivity value in the thickness direction of the low electrical resistance layer is 1/5 or less of the volume resistance value in the thickness direction of the base material layer. A conductive resin laminated film is disclosed. In this laminated film, a low electrical resistance layer formed of a coating film of an elastomer composition containing fine carbon fibers is laminated on a substrate formed by extrusion molding an elastomer composition containing a conductive agent such as carbon black. Yes.

  Japanese Patent Application Laid-Open No. 2008-207404 (Patent Document 2) is obtained by mixing a conductive agent into a conductive resin layer obtained by mixing a conductive agent with a thermoplastic resin and a thermoplastic resin having adhesiveness to a metal. A conductive film characterized by having at least a conductive adhesive resin layer is disclosed. In this conductive film, a conductive resin layer formed by extrusion molding of an elastomer composition containing a conductive agent such as carbon black, and a conductive film formed of a coating film of an acid-modified elastomer composition containing carbon fibers and carbon fibers. An adhesive resin layer is laminated.

  However, as in these patent documents, in order to reduce the thickness of the conductive film, it is necessary to use a soft elastomer or the like as a resin component. However, a soft resin such as an elastomer or an amorphous resin is resistant to solvents. Is low. In particular, in a lithium ion secondary battery, as disclosed in JP-A-2006-32143 (Patent Document 3), a polar solvent having high solubility in a polymer such as ethylene carbonate or propylene carbonate as an electrolyte solution. Therefore, high solvent resistance is required. Furthermore, in patent documents 1 and 2, since the base material is formed by extrusion molding, in order to reduce the thickness, the content of the conductive filler is limited to a small amount, and the conductivity cannot be improved. That is, in a current collector formed of a polymer containing a conductive filler, it is necessary to reduce the proportion of the conductive filler in order to reduce the thickness, and it is difficult to reduce the thickness while maintaining conductivity. It was.

Japanese Patent Application Laid-Open No. 2010-170833 (Patent Document 4) has a structure including one or more layers having a resin and a conductive material, and a crystalline resin having a melting point of 120 ° C. or more is used as the resin. A current collector for a bipolar secondary battery to be used is disclosed. This document describes that the volume resistivity in the thickness direction (film thickness direction) of the current collector is 10 ² Ω or less, preferably 10 ² to 10 ⁻⁵ Ω. Furthermore, in the examples, pellets were prepared by adding 10% by weight ketjen black to a crystalline resin such as polypropylene, and then the pellets were kneaded and rolled with a rolling mill to produce a current collecting sheet having a thickness of 50 μm. is doing. The electrical resistance in the thickness direction of the obtained current collector sheet is 10 to 100Ω (2000 to 20000Ω · cm in terms of volume resistivity per 1 cm thickness), and has good chemical resistance, oxygen barrier property, and heat press resistance. It is described that it is useful as a current collector for a secondary battery such as a lithium ion battery.

  However, even with such a current collector, since the thin film is produced by the kneading and rolling process, the content of the conductive filler is limited to a small amount, the conductivity is low, and the solvent resistance is also low. not enough.

Japanese Patent No. 4349793 (Claim 1, Example) JP 2008-207404 A (Claim 1, Example) JP 2006-32143 A (Claim 1, paragraphs [0042] to [0044]) JP 2010-170833 A (claims, paragraph [0088], examples)

  Accordingly, an object of the present invention is to provide a conductive composite film that is stable with respect to polar solvents (such as aprotic polar solvents) such as alkylene carbonate, has high solvent resistance, and low solvent permeability, and a method for producing the same. There is to do.

  Another object of the present invention is to provide a conductive composite film having a high conductivity even when it is thin, and a method for producing the same.

  Still another object of the present invention is to provide a conductive composite film excellent in light weight despite its high conductivity and a method for producing the same.

  Another object of the present invention is to provide a conductive composite film having high thermal conductivity and excellent mechanical properties such as flexibility and a method for producing the same.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors include a first conductive layer formed of a crystalline resin composition containing a carbon-based conductive filler and a second carbon-based conductive filler. By laminating the second conductive layer formed of a cured product of the photocurable composition, it is stable and highly resistant to polar solvents such as alkylene carbonate, and the permeability of the polar solvent is also high. The present inventors have found that a low conductive composite film can be obtained and completed the present invention.

  That is, the conductive composite film of the present invention includes a first conductive layer formed of a crystalline resin composition containing a crystalline resin and a first carbon-based conductive filler, a photocurable resin, and a second carbon. A second conductive layer formed of a cured product of a photocurable composition containing a system conductive filler is laminated. The first and second carbon-based conductive fillers may be conductive carbon black. In the crystalline resin composition, the ratio (weight ratio) between the crystalline resin and the carbon-based conductive filler may be the former / the latter = 90/10 to 55/45. The crystalline resin may be a polypropylene resin and / or a polyamide resin. The photocurable resin may contain a trifunctional or higher polyfunctional vinyl compound and a monofunctional and / or bifunctional vinyl compound. The bifunctional vinyl compound may contain a chain aliphatic bifunctional (meth) acrylate. The bifunctional vinyl compound may further contain a ring-containing bifunctional (meth) acrylate having an aliphatic ring and / or an aromatic ring. The polyfunctional vinyl compound may be a 3-6 functional (meth) acrylate. The said photocurable composition is an electron beam curable composition, and does not need to contain a polymerization initiator substantially. In the conductive composite film of the present invention, the thickness of the first conductive layer is 1 to 200 μm, the thickness of the second conductive layer is 1 to 100 μm, and the first conductive layer and the second conductive layer are The thickness ratio of the first conductive layer / the second conductive layer may be 1/1 to 20/1. The volume specific resistivity of the first conductive layer may be 0.1 to 1500 Ω · cm, and the volume specific resistivity of the second conductive layer may be 1 to 1000 Ω · cm. In the conductive composite film of the present invention, the weight change rate (weight increase rate) of the first conductive layer after being immersed in tetrahydrofuran at 25 ° C. for 24 hours may be 10% by weight or less. In a dynamic viscoelasticity test measured from −50 ° C. to 250 ° C. under conditions of a temperature rising rate of 5 ° C./min and a frequency of 10 Hz, the storage elastic modulus E ′ in the rubber-like region of the second conductive layer was 200 to 2000 MPa. May be.

  In the present invention, after extruding the crystalline resin composition, the obtained sheet is heated or stretched or rolled while being heated, and on the obtained first conductive layer. The manufacturing method of the said conductive composite film including the shaping | molding process of the 2nd conductive layer which light-irradiates and forms a hardened | cured material after apply | coating a photocurable composition is also contained. In the molding step of the first conductive layer, after the extrusion molding of the crystalline resin composition to mold a sheet having a thickness of 120 to 500 μm, when the melting point of the crystalline resin is mp, (mp-40) The obtained sheet may be stretched or rolled while being heated at a temperature of from 0C to (mp-5) C. In the molding step of the second conductive layer, the photocurable composition may be irradiated with an electron beam to form a cured product.

  In the present invention, a first conductive layer formed of a crystalline resin composition containing a carbon-based conductive filler, and a cured product of a photocurable composition containing a second carbon-based conductive filler. Since the two conductive layers are laminated, it is stable and resistant to polar solvents such as alkylene carbonate, and the permeability of the polar solvent is low. In addition, since carbon-based conductive fillers are filled with high density, even if it is thin, it is highly conductive and has excellent lightness despite having high conductivity. . Furthermore, it has high thermal conductivity and excellent mechanical properties such as flexibility.

[Conductive composite film]
The conductive composite film of the present invention is a photocurable composition containing a first conductive layer formed of a crystalline resin composition containing a first carbon-based conductive filler and a second carbon-based conductive filler. And a second conductive layer formed of the cured product.

(First conductive layer)
The first conductive layer is formed of a crystalline resin composition containing a crystalline resin and a first carbon-based conductive filler.

(A) Crystalline resin Examples of the crystalline resin include olefin resins (polyethylene resins such as high density polyethylene, polypropylene resins, etc.), styrene resins (syndiotactic polystyrene, etc.), polyacetal resins (polyoxy). Methylene, etc.), polyester resins (polyethylene terephthalate, polybutylene terephthalate, polyalkylene arylates such as polyethylene naphthalate, liquid crystal polyesters, etc.), polyamide resins (aliphatic polyamides, etc.), polyphenylene sulfide resins, polyether ether ketone, fluorine Resin (polytetrafluoroethylene etc.) etc. are mentioned. These crystalline resins can be used alone or in combination of two or more.

  Of these crystalline resins, polypropylene resins, polyamide resins, polyphenylene sulfide resins, polyether ether ketones, etc. are preferable because of their excellent heat resistance and mechanical properties. Chemical resistance, moldability, and light weight Polypropylene resins and polyamide resins are particularly preferred from the standpoint of superiority.

(A1) Polypropylene resin The polypropylene resin may be a propylene copolymer (propylene copolymer) as well as a propylene homopolymer (propylene homopolymer). Copolymers include propylene and α-olefins [e.g., ethylene, 1-butene, 2-butene, 1-pentene, 1-hexene, 3-methylpentene, 4-methylpentene, 4-methyl-1-butene, 1 Α-C _2-16 olefins other than propylene such as hexene, 1-octene, 1-nonene, 1-decene, 1-undecene and 1-dodecene (particularly α-C _2-6 olefins such as ethylene and butene), etc. ], For example, propylene-ethylene random copolymer, propylene-butene random copolymer, propylene-ethylene-butene random terpolymer, and the like. In the present invention, from the viewpoints of solvent resistance and heat resistance, it does not substantially contain a copolymerizable unit having a polar group such as maleic acid or (meth) acrylic acid and / or an aromatic vinyl unit such as styrene. Is preferred. Examples of the form of the copolymer include block copolymerization, random copolymerization, and graft copolymerization.

  In the copolymer, the ratio (molar ratio) of propylene and α-olefin (particularly ethylene) is propylene / α-olefin = 90/10 to 100/0, preferably 95/5 to 100/0, more preferably. It is about 99/1 to 100/0. When the proportion of α-olefin is too small, crystallinity is lowered, and solvent resistance and heat resistance are lowered. In the present invention, a homopolymer is preferred.

  The polypropylene resin may be an atactic polymer, but from the viewpoint of improving crystallinity, a structure having stereoregularity such as isotactic and syndiotactic is preferable, and an isotactic polymer is particularly preferable.

  Further, the polypropylene resin may be a polymer using a Ziegler catalyst, but a metallocene resin using a metallocene catalyst from the viewpoint of obtaining a polymer having a low molecular weight tack component and a narrow molecular weight distribution. It is preferable to contain at least (particularly a metallocene copolymer).

  The specific gravity of the polypropylene resin is 1.00 or less (particularly 0.95 or less), for example, 0.80 to 0.95, preferably 0.85 to 0.95, and more preferably 0.87 to 0.93. (Especially about 0.89 to 0.91).

  The melting point of the polypropylene resin (melting peak temperature in the differential scanning calorimeter DSC) can be selected from a range of about 100 to 170 ° C., for example, but is 110 to 170 ° C., preferably 120 to 120 ° C. from the viewpoint of heat resistance. It is about 168 ° C., more preferably about 130 to 166 ° C. (especially 160 to 166 ° C.). In the present specification, the melting point of the polypropylene resin is measured in the form of pellets prepared by melt mixing with the conductive filler.

(A2) Polyamide resin Examples of polyamide resins include polyamides obtained by polycondensation of diamine and dicarboxylic acid, polyamides obtained by polycondensation of aminocarboxylic acid, and polyamides obtained by ring-opening polymerization of lactam. And polyamides obtained by polymerizing these monomers in combination.

  Examples of the diamine include trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, octamethylenediamine, and nonamethylene. Aliphatic diamines such as diamines; and alicyclic diamines such as bis (4-aminocyclohexyl) methane and bis (4-amino-3-methylcyclohexyl) methane. In addition, aromatic diamines such as phenylenediamine and metaxylylenediamine may be used in combination. These diamines can be used alone or in combination of two or more.

Examples of the dicarboxylic acid include C _4-20 aliphatic dicarboxylic acids such as glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and octadecanedioic acid; dimerized fatty acid (dimer acid); cyclohexane Examples include alicyclic dicarboxylic acids such as -1,4-dicarboxylic acid and cyclohexane-1,3-dicarboxylic acid; aromatic dicarboxylic acids such as phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, and naphthalenecarboxylic acid. . These dicarboxylic acids can be used alone or in combination of two or more.

Examples of aminocarboxylic acids include C _4-20 aminocarboxylic acids such as aminoheptanoic acid, aminononanoic acid, and aminoundecanoic acid. Aminocarboxylic acids can be used alone or in combination of two or more. These aminocarboxylic acids can be used alone or in combination of two or more.

Examples of the lactam include C _4-20 lactams such as butyrolactam, bivalolactam, caprolactam, capryllactam, enantolactam, undecanolactam, and dodecalactam. These lactams can be used alone or in combination of two or more.

  Polyamide resins include aliphatic polyamides such as polyamide 46, polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 11 and polyamide 12, aromatic dicarboxylic acids (for example, terephthalic acid and / or isophthalic acid) and aliphatic. Obtained from polyamides obtained from diamines (eg hexamethylenediamine, nonamethylenediamine, etc.), aromatic and aliphatic dicarboxylic acids (eg terephthalic acid and adipic acid) and aliphatic diamines (eg hexamethylenediamine) Examples thereof include polyamide. These polyamide-based resins are not limited to homopolyamide but may be copolyamide. These polyamide resins can be used alone or in combination of two or more.

Of these polyamide-based resins, aliphatic polyamides such as polyamide 46, polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 11, and polyamide 12 are preferable because of high crystallinity and excellent heat resistance. These aliphatic polyamides can be selected depending on the use, and when improving crystallinity such as uses where heat resistance and gas barrier properties are important, aliphatic polyamides having a C _2-12 alkylene chain (particularly polyamide 46). And aliphatic polyamides having a C _3-8 alkylene chain such as polyamide 66). In applications where moldability and solvent resistance are important, aliphatic polyamides having C _8-16 alkylene chains (particularly aliphatic polyamides having C _10-14 alkylene chains such as polyamide 11 and polyamide 12) are preferred.

  The specific gravity of the polyamide resin is 1.05 or less, for example, about 0.80 to 1.04, more preferably about 0.85 to 1.02.

  The melting point of the polyamide-based resin (melting peak temperature in the differential scanning calorimeter DSC) can be selected from a range of about 100 to 250 ° C., for example, but is 140 to 220 ° C., preferably 150 to 150 ° C. from the viewpoint of heat resistance. It is 200 degreeC, More preferably, it is about 160-190 degreeC (especially 170-180 degreeC) grade. In the present specification, the melting point of the polyamide-based resin is measured in the state of pellets prepared by melt mixing with the conductive filler.

  Of these crystalline resins, polypropylene resins are particularly preferred because they are excellent in chemical resistance, gas barrier properties, toughness, and economy in addition to the above-mentioned properties. In particular, when a polypropylene resin is used, the effect of reducing the weight is remarkable. Furthermore, polypropylene resin is more preferably used in applications that require low moisture permeability or water absorption.

(B) First carbon-based conductive filler Examples of the first carbon-based conductive filler include artificial graphite, expanded graphite, natural graphite, coke, carbon nanotube, conductive carbon black, and carbon fiber. In the present invention, since a carbon-based conductive filler is used as the conductive filler, it is superior in lightness compared to a metal filler, and even if a large amount of filler is blended with the crystalline resin, the lightness is not greatly impaired. These conductive fillers can be used alone or in combination of two or more.

  Although it is difficult to determine the true specific gravity of carbon-based conductive fillers, especially nano-level particulate fillers, the specific gravity of carbon-based conductive fillers is 2.5 or less, for example, 0.30 to 2.5, preferably Is about 0.45 to 2.0, more preferably about 1.0 to 2.0 (especially 1.4 to 1.9).

  Examples of the shape of these carbon-based conductive fillers include particulate (powder), plate (or scale), fibrous, and indefinite shape. Of these shapes, particle shapes such as a substantially spherical shape and a polygonal shape are widely used.

  In the present invention, among these carbon-based conductive fillers, conductive carbon black is preferable from the viewpoint of conductivity and lightness.

  Examples of the conductive carbon black include furnace black, channel black, gas black, acetylene black, arc black, and ketjen black. These conductive carbon blacks can be selected depending on the application.For example, acetylene black with low oil content may be used to improve flame retardancy, and hollow shell structure ketjen black is used to improve lightness. May be. Of these conductive carbon blacks, furnace black, ketjen black, acetylene black and the like are preferable from the viewpoint of conductivity. Further, a conductive composite carbon black obtained by combining these conductive carbon blacks may be used.

  Commercially available products of conductive carbon black include Ketjen Black (“EC600JD” manufactured by Ketjen Black International Co., Ltd.), Ketjen Black (“EC300J” manufactured by Ketjen Black International Co., Ltd.), Ketjen Black ( “MBP1853” manufactured by Ketjen Black International Co., Ltd.), acetylene black (“Denka Black HS-100” manufactured by Denki Kagaku Kogyo Co., Ltd.), furnace carbon black (“Toka Black # 5500” manufactured by Tokai Carbon Co., Ltd.) Examples include conductive carbon blacks having different characteristics such as particle diameter and cohesiveness, such as “Toka Black # 4300”) and “# 3030B” and “# 3400B” manufactured by Mitsubishi Chemical Corporation.

  The average primary particle size (calculated average particle size obtained by observation with a transmission electron microscope) of the first carbon-based conductive filler (for example, conductive carbon black) can be appropriately selected from a range of about 10 μm or less. From the point to disperse | distribute in a layer, 1 micrometer or less is preferable, Furthermore, from the point which can suppress the smoothness of a 1st conductive layer, a pinhole, and a tear, etc., for example, 1-1000 nm, Preferably it is 5-100 nm, More preferably, 10 It is about ~ 60nm (especially 10-50nm).

  In the first conductive layer, the first carbon-based conductive filler (for example, conductive carbon black) has such a primary particle size, but the primary particles in the layer are aggregates (aggregates). ) Is further formed. It can be presumed that this aggregate structure is maintained even in a thin layer, forms a network structure with many contact points between particles, and improves the conductivity of the film.

The first carbon-based conductive filler (e.g., conductive carbon black) DBP (dibutyl phthalate) oil absorption amount of (A method of JIS K6221), depending on the application, 10~1000cm ³ / 100g (e.g., 30～500Cm ^3/100 g) may be selected from the range of about, nitrogen adsorption BET specific surface area ^{20 m} 2 / g or more, preferably ^{30 m} 2 / g or more (e.g., 30~2000m ² / g), more preferably 100 m ² / g or more ( For example, it can select from the range of about 100-1500 m < ² > / g).

  The ratio (weight ratio) between the crystalline resin and the first carbon-based conductive filler is the former / the latter = 90/10 to 55/45, preferably 85/15 to 55/45, more preferably 85 / It is about 15-60 / 40 (especially 80 / 20-60 / 40). When the content of the conductive filler is too small, the volume specific resistance value of the thin first conductive layer is increased, and conversely, when the content is too large, the sheet formability and sheet physical properties tend to be lowered.

  Note that special fillers (such as ketjen black) that have internal voids or cavities such as hollow structures and tube structures have a small apparent density and therefore have a large volume and an aggregate structure with respect to the weight added to the resin composition. On the other hand, the influence of the filler on the kneading and melt extrusion characteristics becomes larger. Therefore, although the true specific gravity of the composition is low and a film having high electrical conductivity can be obtained even with a small addition amount, the upper limit of the addition weight is higher than other carbon-based fillers with a large apparent density because of the workability of the composition. Tend to be low. In addition, a structure having voids or cavities is destroyed by mechanical shearing force such as kneading, extrusion molding, stretching, rolling, etc., compared to a filler having substantially no internal voids or cavities, such as acetylene black. Tend. Therefore, when using the filler which has a space | gap inside, it is necessary to pay attention to the conditions in each process.

  The ratio between the crystalline resin and the first carbon-based conductive filler may be adjusted according to the specific gravity of the carbon-based conductive filler, and although it is difficult to determine the true specific gravity of nano-level granular carbon black, for example, In the case of a filler (for example, acetylene black) having a specific gravity of 2.0 to 1.7 (particularly 1.9 to 1.8), crystalline resin / first carbon-based conductive filler = 80/20 to 55 / 45, preferably 75/25 to 55/45, more preferably about 70/30 to 60/40. In the case of a filler (for example, acetylene black) having a specific gravity of 0.3 to 1.6 (particularly 0.4 to 1.5), crystalline resin / first carbon-based conductive filler = 90/10 to 70. / 30, preferably 90/10 to 80/20, more preferably about 90/10 to 85/15.

(C) Other Additives The first conductive layer is made of a conventional additive such as other polymer (amorphous resin, amorphous elastomer, crystalline elastomer, rubber, etc.), plasticizer, other Conductive filler, conductive polymer, stabilizer (thermal stabilizer, ultraviolet absorber, light stabilizer, antioxidant, etc.), dispersant, antistatic agent, colorant, lubricant, crystal nucleating agent, flame retardant, It may contain flame retardant aids, fillers, impact resistance improvers, reinforcing agents, foaming agents, antibacterial agents and the like. These additives can be used alone or in combination of two or more. The ratio of these additives is, for example, 10 parts by weight or less, preferably 0.01 to 5 parts by weight, more preferably 0, with respect to 100 parts by weight of the total of the crystalline resin and the first carbon-based conductive filler. About 0.05 to 3 parts by weight (particularly 0.1 to 2 parts by weight).

  The first conductive layer may contain a soft component such as an elastomer or rubber as long as it is in the above ratio, but substantially contains a soft component such as an elastomer or rubber (especially an elastomer such as an amorphous elastomer). It does not need to contain. In the present invention, the first conductive layer having a thin wall and high conductivity can be prepared without containing a soft component, although the resin component is substantially formed of a crystalline resin.

(Characteristics of the first conductive layer)
The first conductive layer is a thin layer having a thickness of 200 μm or less. Specifically, the thickness of the first conductive layer can be selected from the range of about 5 to 150 μm (for example, 5 to 120 μm), preferably 10 to 110 μm, more preferably about 15 to 100 μm (particularly 20 to 100 μm). In applications where thin walls are required, the thickness may be, for example, about 25 to 50 μm (particularly 30 to 45 μm).

  The first conductive layer also has high thickness uniformity, and the thickness variation ratio (maximum thickness / minimum thickness) is, for example, 1.5 or less (for example, 1 to 1.5), preferably 1.01 to 1. 4, more preferably about 1.03 to 1.3 (particularly 1.05 to 1.25), for example, about 1.1 to 1.2. Since the first conductive layer has a uniform thickness, for example, even when a plurality of films are laminated, a large gap does not occur, and the adhesiveness is high, and the conductivity uniformity and stability are also high. The thickness variation ratio can be measured by the method described in Examples described later.

  The first conductive layer has high conductivity while being thin. That is, the volume resistivity of the first conductive layer is 0.1 to 1500 Ω · cm, preferably 1 to 1000 Ω · cm, more preferably 2 to 500 Ω · cm (particularly 3 to 100 Ω · cm). For example, about 1-50 ohm * cm (especially 2-10 ohm * cm) may be sufficient. The volume resistance value of the first conductive layer is, for example, about 0.001 to 5Ω, preferably about 0.01 to 3Ω, and more preferably about 0.1 to 1Ω.

  The first conductive layer is also excellent in solvent resistance, and the weight change rate (weight increase rate) after being immersed in tetrahydrofuran at 25 ° C. for 24 hours is 10% by weight or less. % By weight, preferably 0.5 to 5.0% by weight, more preferably about 0.5 to 4.0% by weight. For applications that require high solvent resistance, for example, 0.5 to 3%. It may be about 0.0% by weight, preferably 0.5 to 2.0% by weight, more preferably about 0.5 to 1.5% by weight (particularly 0.5 to 1.0% by weight).

  The specific gravity of the first conductive layer is, for example, about 0.75 to 1.20, preferably about 0.80 to 1.18, more preferably about 0.85 to 1.15 (particularly 0.90 to 1.15). It is. When the crystalline resin is a polypropylene resin, the specific gravity of the first conductive layer is, for example, 0.95 to 1.2, preferably 0.96 to 1.18, and more preferably 0.97 to 1.15. It may be about (especially 1.0 to 1.1).

(Second conductive layer)
The second conductive layer is formed of a cured product of a photocurable composition containing a photocurable resin and a second carbon-based conductive filler.

(A) Photocurable resin The photocurable resin contains a trifunctional or higher polyfunctional vinyl compound and a monofunctional and / or bifunctional vinyl compound.

(A) Polyfunctional vinyl compound The polyfunctional vinyl compound only needs to have 3 or more (for example, about 3 to 8) polymerizable groups (α, β-ethylenically unsaturated bond) in the molecule. Specifically, polyfunctional (meth) acrylates having 3 or more (meth) acryloyl groups are widely used.

As polyfunctional (meth) acrylate, esterified product of polyhydric alcohol and (meth) acrylic acid, for example, glycerin tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, Examples include pentaerythritol tri (meth) acrylate; ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate; dipentaerythritol penta (meth) acrylate; dipentaerythritol hexa (meth) acrylate, and the like. Further, in these polyfunctional (meth) acrylates, the polyhydric alcohol may be an adduct of alkylene oxide (for example, C _2-4 alkylene oxide such as ethylene oxide or propylene oxide). The average addition mole number of alkylene oxide can be selected from the range of about 0-30 mol (especially 1-10 mol), for example. These polyfunctional (meth) acrylates can be used alone or in combination of two or more.

  Among these polyfunctional vinyl compounds, 3-6 functional (meth) acrylates such as trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate and pentaerythritol tetra (meth) acrylate are preferable, and pentaerythritol tris. 3 to 4 functional (meth) acrylates such as (meth) acrylate are widely used. Furthermore, the polyfunctional vinyl compound is preferably an unmodified polyfunctional vinyl compound that has not been modified with an amine (a polyfunctional vinyl compound in which amines are not added by Michael addition or the like).

(B) Monofunctional and / or bifunctional vinyl compound The monofunctional and / or bifunctional vinyl compound has one or two polymerizable groups (α, β-ethylenically unsaturated bond) in the molecule. Specifically, it may be an aromatic vinyl compound such as styrene or divinylbenzene, but from the viewpoint of photopolymerization and the like, monofunctional or 2 having one or two (meth) acryloyl groups Functional (meth) acrylates are widely used.

(B1) Monofunctional vinyl compound Examples of the monofunctional vinyl compound include (meth) acrylic acid; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl ( (Meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, _{C 1-24} alkyl (meth) such as stearyl (meth) acrylate acrylate; cyclohexyl (meth) cycloalkyl (meth) acrylates such as acrylate; dicyclopentanyl ( ) Acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, etc. ) Acrylate; aryl (meth) acrylates such as phenyl (meth) acrylate and nonylphenyl (meth) acrylate; aralkyl (meth) acrylates such as benzyl (meth) acrylate; hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxy _{C 2-10} alkyl (meth) acrylate or _{C 2-10} alkanediol mono (meth) acrylates such as hydroxybutyl (meth) acrylate; trifluoroethyl (meth Alkoxyalkyl (meth) acrylates such as methoxyethyl (meth) acrylate; acrylate, tetrafluoropropyl (meth) acrylate, fluoroalkyl C _1-10 alkyl (meth) acrylates such as hexafluoroisopropyl (meth) acrylate and phenoxyethyl (meth) Aryloxyalkyl (meth) acrylates such as acrylate and phenoxypropyl (meth) acrylate; aryloxy (poly) such as phenyl carbitol (meth) acrylate, nonylphenyl carbitol (meth) acrylate, and nonylphenoxypolyethylene glycol (meth) acrylate Alkoxyalkyl (meth) acrylates; Polyalkylene glycol mono (meth) acrylates such as polyethylene glycol mono (meth) acrylate ) Acrylate; alkane polyol mono (meth) acrylate such as glycerin mono (meth) acrylate; 2-dimethylaminoethyl (meth) acrylate, 2-diethylaminoethyl (meth) acrylate, 2-t-butylaminoethyl (meth) acrylate, etc. (Meth) acrylate having an amino group or a substituted amino group; glycidyl (meth) acrylate and the like.

(B2) Bifunctional vinyl compound Examples of the bifunctional vinyl compound include allyl (meth) acrylate; ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, and 1,3-propanediol di (meth). Alkanediol di (meth) acrylates such as acrylate, 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate; glycerin di (meth) acrylate Alkane polyol di (meth) acrylate such as: Diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate Polyalkylene glycol di (meth) acrylates such as polypropylene glycol di (meth) acrylate; 2,2-bis (4- (meth) acryloxyethoxyphenyl) propane, 2,2-bis (4- (meth) acrylic Di (meta) of C _2-4 alkylene oxide adducts of bisphenols (bisphenol A, bisphenol S, etc.) such as loxydiethoxyphenyl) propane and 2,2-bis (4- (meth) acryloxypolyethoxyphenyl) propane ) Acrylates; di (meth) acrylates of alkane polyol partial esters such as pentaerythritol fatty acid esters; and bridged cyclic di (meth) acrylates such as tricyclodecane dimethanol di (meth) acrylate and adamantane di (meth) acrylate Exemplification it can.

  Furthermore, as a bifunctional vinyl compound, for example, epoxy di (meth) acrylate (such as bisphenol A type epoxy di (meth) acrylate), polyester di (meth) acrylate (for example, aliphatic polyester type di (meth) acrylate, aromatic Examples include oligomers or resins such as polyester-type di (meth) acrylate), (poly) urethane di (meth) acrylate (polyester-type urethane di (meth) acrylate, polyether-type urethane di (meth) acrylate, etc.), and silicone (meth) acrylate. it can.

  These vinyl compounds can be used alone or in combination of two or more. Among these vinyl compounds, a bifunctional (meth) acrylate is preferable from the viewpoint of reactivity and solvent resistance, and a chain aliphatic having a chain aliphatic skeleton from the viewpoint of improving the flexibility of the cured product. Bifunctional (meth) acrylates including bifunctional (meth) acrylates are particularly preferred.

(B2-1) Chain aliphatic bifunctional (meth) acrylate The chain aliphatic bifunctional (meth) acrylate may have an alkylene chain. For example, 1,4-butanediol di (meth) C _2-12 alkanediol di (meth) acrylate such as acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate; di (meth) acrylate of alkane polyol fatty acid ester; aliphatic polyester Type di (meth) acrylate; aliphatic polyester type urethane di (meth) acrylate and the like. Moreover, the chain | strand-shaped aliphatic skeleton may be introduce | transduced into the (meth) acrylate which has an aliphatic ring and / or an aromatic ring. Furthermore, the number of carbon atoms of the alkylene chain constituting the chain aliphatic skeleton can be selected from a range of, for example, about 3 to 20, but is preferably 4 to 12, for example, from the viewpoint of the balance between flexibility and solvent resistance. Is preferably 4 to 10, more preferably about 4 to 8 (particularly 5 to 8). These chain aliphatic bifunctional (meth) acrylates can be used alone or in combination of two or more.

  Further, the chain aliphatic bifunctional (meth) acrylate particularly preferably contains a lactone-derived unit and / or an aliphatic polyester unit.

Examples of the lactone include C ₃ such as γ-butyrolactone (GBL), γ-valerolactone, δ-valerolactone, β-methyl-δ-valerolactone, γ-caprolactone, and enanthlactone (7-hydroxyheptanoic acid lactone). _{And -10} lactone. These lactones can be used alone or in combination of two or more. Of these lactones, C _4-8 lactones (particularly C _5-8 lactones) such as valerolactone and caprolactone are preferred.

Examples of the aliphatic polyester include aliphatic dicarboxylic acids or anhydrides thereof (C _4-20 alkanedicarboxylic acids such as succinic acid, succinic anhydride, adipic acid, azelaic acid, and sebacic acid) and aliphatic diols (ethylene glycol). Reaction products with C _2-10 alkanediols such as propylene glycol and tetramethylene ether glycol), reaction products obtained by ring-opening addition polymerization of the lactone with respect to the initiator, and the like. The degree of polymerization of the polyester unit can be appropriately selected from a range of, for example, about 2 to 100, and may be, for example, 3 to 90, preferably 5 to 80, and more preferably about 10 to 70.

Examples of chain aliphatic bifunctional (meth) acrylates containing lactone-derived units and / or aliphatic polyester units include aliphatic polyester _diesters having polyester units obtained by ring-opening polymerization of C _5-8 lactones such as caprolactone. (Meth) acrylate, urethane di (meth) acrylate having the polyester unit, epoxy di (meth) acrylate having the polyester unit, and the like can be used.

  Furthermore, the polyisocyanate unit of the polyester type urethane di (meth) acrylate may be any of aliphatic polyisocyanate, alicyclic polyisocyanate, and aromatic polyisocyanate, and aliphatic polyisocyanate such as hexamethylene diisocyanate is widely used. . The epoxy di (meth) acrylate having a polyester unit may be a bisphenol-type epoxy (meth) acrylate such as bisphenol A.

(B2-2) Ring-containing bifunctional (meth) acrylate A monofunctional and / or bifunctional vinyl compound, in addition to the vinyl compound having a chain aliphatic skeleton, further improves solvent resistance. A ring-containing (meth) acrylate having an aliphatic ring and / or an aromatic ring may be included.

The ring-containing bifunctional (meth) acrylate may have an aliphatic ring and / or an aromatic ring in the molecule. For example, tricyclodecane dimethanol di (meth) acrylate, adamantane di (meth) acrylate C _6-20 (especially C _8-12 ) bridged 2-4 cyclic di (meth) acrylate; 2,2-bis (4- (meth) acryloxyethoxyphenyl) propane, 2,2-bis ( 4- (meth) acryloxypropoxyphenyl) propane, 2,2-bis (4- (meth) acryloxydiethoxyphenyl) propane, 2,2-bis (4- (meth) acryloxypolyethoxyphenyl) propane, etc. bisphenols (bisphenol a, S, _{etc.) -C 2-4} alkylene oxide adducts [average addition mole number of alkylene oxide 0-30 Di (meth) acrylates, oligomers [aromatic epoxy (meth) acrylates such as bisphenol A type epoxy (meth) acrylates, novolac type epoxy (meth) acrylates, etc.]] and the like. . These bifunctional (meth) acrylates can be used alone or in combination of two or more.

Among these ring-containing bifunctional (meth) acrylates, polycyclic alicyclic rings such as tricyclodecane dimethanol di (meth) acrylate and adamantane di (meth) acrylate are used because of the high solvent resistance and strength of the cured product. Di (meth) acrylate having a bisphenol skeleton such as di (meth) acrylate having a group skeleton, 2,2-bis (4- (meth) acryloxyethoxyphenyl) propane, bisphenol A type epoxy (meth) acrylate, Particularly preferred are di (meth) acrylates having a C _8-12 bridged 2-4 cyclic alicyclic skeleton such as tricyclodecane dimethanol di (meth) acrylate.

  The proportion of the ring-containing bifunctional (meth) acrylate can be appropriately selected from the range of about 0 to 500 parts by weight with respect to 100 parts by weight of the chain aliphatic bifunctional (meth) acrylate according to the target viscoelasticity. 5 to 200 parts by weight, preferably 10 to 100 parts by weight (for example, 20 to 80 parts by weight), more preferably about 30 to 60 parts by weight (particularly 40 to 50 parts by weight). In the present invention, flexibility can be improved while maintaining solvent resistance by combining the chain aliphatic bifunctional (meth) acrylate and the ring-containing bifunctional (meth) acrylate at such a ratio.

  The proportion of the monofunctional and / or bifunctional vinyl compound can be selected from the range of about 1 to 1000 parts by weight with respect to 100 parts by weight of the polyfunctional vinyl compound, for example, 5 to 500 parts by weight, preferably 10 to 10 parts by weight. About 300 parts by weight.

  In the present invention, the monofunctional and / or bifunctional vinyl compound can be selected from the above range depending on the type of the monofunctional and / or bifunctional vinyl compound. For example, the monofunctional and / or bifunctional vinyl compound is a chain aliphatic bifunctional (meth) acrylate and In the case of a combination with a ring-containing bifunctional (meth) acrylate, the proportion of the monofunctional and / or bifunctional vinyl compound is, for example, 30 to 500 parts by weight, preferably 100 parts by weight of the polyfunctional vinyl compound. Is about 50 to 300 parts by weight, more preferably about 100 to 200 parts by weight (particularly 120 to 150 parts by weight).

  When the monofunctional and / or bifunctional vinyl compound is a chain aliphatic bifunctional (meth) acrylate, the ratio of the monofunctional and / or bifunctional vinyl compound is 100 parts by weight of the polyfunctional vinyl compound. On the other hand, it is about 1-100 weight part, for example, Preferably it is 5-50 weight part, More preferably, it is about 10-40 weight part (especially 20-30 weight part).

(B) Second carbon-based conductive filler As the second carbon-based conductive filler, the carbon-based conductive filler exemplified in the section of the first carbon-based conductive filler can be used. The specific gravity and shape of the second carbon-based filler are the same as those of the first carbon-based filler, and conductive carbon black is preferable as the second carbon-based filler.

  As the second conductive carbon black, the conductive carbon black exemplified in the section of the first carbon-based conductive filler can be used. The average primary particle size, DBP oil absorption, and specific surface area of the second carbon black are the same as those of the first carbon-based conductive filler.

  The ratio of the second carbon-based conductive filler is about 1 to 100 parts by weight with respect to 100 parts by weight of the photocurable resin (the total amount of the polyfunctional vinyl compound and the monofunctional and / or bifunctional vinyl compound). It can be selected from the range, for example, about 3 to 80 parts by weight, preferably about 5 to 50 parts by weight, more preferably about 10 to 40 parts by weight (particularly 15 to 35 parts by weight), and particularly ensures the flexibility of the cured product. Therefore, it may be 45 parts by weight or less (particularly about 5 to 40 parts by weight).

(C) Other additives The photocurable composition may contain an organic solvent. Examples of the organic solvent include ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), ethers (dioxane, tetrahydrofuran, etc.), aliphatic hydrocarbons (hexane, etc.), alicyclic hydrocarbons (cyclohexane, etc.) ), Aromatic hydrocarbons (benzene, toluene, xylene, etc.), halogenated carbons (dichloromethane, dichloroethane, etc.), esters (methyl acetate, ethyl acetate, etc.), water, alcohols (ethanol, isopropanol, butanol, cyclo Hexanol, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, etc.), cellosolve acetates, amides (dimethylformamide, dimethylacetamide, etc.) and the like. These organic solvents can be used alone or in combination of two or more. Of these organic solvents, ketones such as methyl ethyl ketone, aromatic hydrocarbons such as toluene, etc. are widely used. For the purpose of improving the properties such as coating properties, monofunctional vinyl compounds such as styrene and other vinyl compounds such as (meth) acrylic acid may be used as the reactive diluent.

  The ratio of the solvent can be selected from a range of about 10 to 1000 parts by weight with respect to 100 parts by weight of the photocurable resin, and for example, 50 to 500 parts by weight, preferably 80 to 300 parts by weight, and more preferably 100 to 200 parts by weight. Part (particularly 120 to 180 parts by weight).

  The photocurable composition may further contain a conventional additive, for example, the additive exemplified in the first conductive layer, alone or in combination of two or more. The ratio of the additive is, for example, 10 parts by weight or less, preferably 0.01 to 5 parts by weight, and more preferably 0.000 parts by weight with respect to 100 parts by weight in total of the photocurable resin and the second carbon-based conductive filler. It is about 05 to 3 parts by weight (particularly 0.1 to 2 parts by weight).

  However, the photocurable composition may not substantially contain a polymerization initiator (for example, a photopolymerization initiator, a photosensitizer, a thermal polymerization initiator, etc.) when cured with an electron beam. Furthermore, it is preferable that a photocurable composition does not contain a thermoplastic resin (especially polyphenylene oxide resin) substantially as a resin component from the point of solvent resistance.

(Hardened product of photocurable composition)
The second conductive layer formed of a cured product is obtained by irradiating and curing the photocurable composition as will be described later, and is −50 under conditions of a heating rate of 5 ° C./min and a frequency of 10 Hz. In the dynamic viscoelasticity test measured from ℃ to 250 ℃, the storage elastic modulus E ′ in the rubbery region is 200 to 2000 MPa, preferably 300 to 1500 MPa, more preferably about 350 to 1200 MPa (particularly 400 to 1000 MPa). is there. In addition, the rubber-like region is substantially flat in the vicinity of 10 ⁶ to 10 ⁷ Pa after passing through a transition region in which the storage elastic modulus-temperature curve greatly decreases as the temperature rises from a glassy region of about 10 ¹⁰ Pa. Means an area to become.

  Since the second conductive layer (cured product) has such a storage elastic modulus E ′, it has an appropriate crosslinking density, excellent solvent resistance, and contains a second carbon-based conductive filler. Despite excellent conductivity, it has moderate flexibility. In particular, there is a trade-off between the relationship between solvent resistance and flexibility, and the relationship between the improvement in conductivity and the improvement in the above characteristics due to the addition of the conductive filler, and these properties are well balanced. Although the second conductive layer is difficult to do, the viscoelasticity of the photocured product is adjusted by adjusting the type and ratio of the resin component, the number of functional groups, the molecular weight (viscosity), the type and blending amount of the conductive filler, etc. By controlling the value within the above range, both characteristics are obtained.

The second conductive layer is excellent in conductivity and may have a volume resistivity of 10 ⁵ Ω · cm or less, for example, 10 ⁴ Ω · cm or less (for example, 0.01 to 10 ⁴ Ω · cm). , Preferably 10 ³ Ω · cm or less (for example, 0.1 to 10 ³ Ω · cm), more preferably 10 ² Ω · cm or less (particularly 10 Ω · cm or less).

  The thickness of the second conductive layer can be selected from the range of about 1 to 100 μm depending on the application, and is, for example, about 1 to 80 μm, preferably 3 to 50 μm, more preferably 5 to 30 μm (particularly 8 to 20 μm). .

(Characteristics of conductive composite film)
The conductive composite film obtained by laminating the first conductive layer and the second conductive layer is excellent in solvent resistance and has high conductivity even though it is thin. The volume resistivity of the conductive composite film may be 10 ⁵ Ω · cm or less, for example, 1 to 10000 Ω · cm (for example, 2 to 1000 Ω · cm), preferably 3 to 500 Ω · cm, more preferably About 5-100 ohm * cm (especially 10-50 ohm * cm) may be sufficient.

  The conductive composite film has high solvent resistance and particularly low permeability to polar solvents. Specifically, in accordance with the method described in the examples described later, propylene carbonate was sealed between two conductive composite films laminated with the second conductive layers facing each other, for 14 days. The weight change rate (weight increase rate) after elapse is, for example, 5% by weight or less, preferably 1% by weight or less (for example, 0.01 to 1% by weight), more preferably 0.5% by weight or less (for example, 0.1 to 0.5% by weight).

  The thickness of the conductive composite film can be selected from the range of about 1 to 300 μm depending on the application, for example, can be selected from the range of about 1 to 250 μm (for example, 5 to 200 μm), preferably 10 to 150 μm, more preferably It is about 15-120 micrometers (especially 20-100 micrometers), and is usually about 25-80 micrometers (for example, 30-50 micrometers).

  The thickness ratio between the first conductive layer and the second conductive layer can be selected from the range of the first conductive layer / second conductive layer = 1/10 to 100/1. / 1, preferably 1/3 to 30/1, more preferably 1/1 to 20/1 (particularly 2/1 to 15/1), and 2/1 to 10/1 (for example, 3/1). About 9/1).

  The conductive composite film of the present invention is not limited to a two-layer structure, for example, a three-layer structure in which a second layer is laminated on both sides of a first layer, and a three-layer structure in which a first layer is laminated on both sides of a second layer Alternatively, a multilayer structure of four or more layers in which the first layer and the second layer are alternately stacked may be used. The conductive composite film of the present invention may further include other layers such as a functional layer (a hard coat layer, another conductive layer, an antistatic layer, an optical layer, etc.). Of these, the current collector of the bipolar battery preferably has a two-layer structure from the viewpoint of thinness.

  The conductive composite film of the present invention is excellent in flexibility and can be made into a sheet and manufactured by a roll-to-roll method. Therefore, the productivity is high and the industrial value is high.

[Method for producing conductive composite film]
The method for producing a conductive composite film of the present invention includes a first conductive layer forming step in which a crystalline resin composition is extruded and then the obtained sheet is stretched or rolled while heating, and the obtained first step is performed. After the photocurable composition is applied onto one conductive layer, the method includes a step of forming a second conductive layer that is irradiated with light to form a cured product.

(First conductive layer forming step)
The crystalline resin composition used in the first molding step may be a pellet prepared by previously melt-kneading the crystalline resin and the first carbon-based conductive filler. As a method of melt kneading, a conventional method, for example, a method using a mixer such as a pressure kneader kneader, a Banbury mixer, a mixing roll, or the like can be used. Furthermore, you may pelletize using a feeder luder etc. after melt-kneading. In this invention, workability | operativity, such as adjustment between each process of sheet | seat processing, can be improved by pelletizing. In addition, as a method of melt kneading, each component may be dry-mixed with a Henschel mixer or a ribbon mixer, and melt kneading and pelletization may be simultaneously performed using a single screw or twin screw extruder.

  The obtained pellet or dry mixture is produced into a sheet using an extruder (for example, a single-screw or twin-screw extruder) or a calendar molding machine, and usually the pellet is melt-kneaded in the extruder, Molding is performed by extruding from the slit of the die (die) at the tip of the extruder. The die (die) may be a ring die used for inflation molding, but usually a T die such as a multi-manifold die or a flat die can be used. Further, the extruded sheet can be cooled by a cooling roll and wound on a sheet winder.

  The conditions for extrusion molding can be selected according to the type of the extruder and the crystalline resin, and the molding temperature is usually about 100 to 280 ° C, preferably about 150 to 260 ° C, more preferably about 180 to 250 ° C. The cooling temperature by a cooling roll is 80-200 degreeC, for example, Preferably it is 100-180 degreeC, More preferably, it is about 120-160 degreeC. Further, the gap (clearance or gap) of the extrusion slit is 0.5 to 2.0 mm, preferably 0.6 to 1.5 mm, and more preferably 0.7 to 1.0 mm. The take-up speed (winding speed) is, for example, about 0.1 to 70 m / min, preferably 0.5 to 40 m / min, more preferably about 1.5 to 30 m / min (particularly 2 to 10 m / min). .

  In the present invention, each resin composition is extruded to 120 to 500 μm, preferably 130 to 400 μm, and more preferably 130 to 300 μm (particularly 130 to 250 μm). The winding speed is adjusted.

  In the present invention, the sheet is once adjusted to such a thickness by extrusion molding. In this state, the first carbon-based conductive filler is appropriately aggregated (aggregated) in the sheet to form a network structure. Because of the formation, it exhibits high conductivity. The obtained sheet has a volume resistivity of 1000 Ω · cm or less, preferably 0.1 to 500 Ω · cm, more preferably 0.2 to 200 Ω · cm (particularly 0.3 to 100 Ω · cm). .

  The roll sheet obtained by extrusion molding is rewound and stretched or rolled. The stretching or rolling process is performed in a state where the sheet is heated. In the method of the present invention, the stretching or rolling process is performed in order to prevent the network structure of the conductive filler formed by the extrusion from being destroyed by the stretching or rolling process. The heating temperature in is controlled. The heating temperature in the stretching or rolling treatment is a temperature range of (mp-40) ° C. to (mp-5) ° C., preferably (mp−35) ° C. to (mp, where mp is the melting point of the crystalline resin. −5) ° C., more preferably (mp-30) ° C. to (mp-10) ° C. [particularly, (mp-30) ° C. to (mp-15) ° C.]. If the heating temperature is too high, the conductivity decreases because the molecular chain of the molten polymer enters the network structure of the conductive filler. In addition, the polymer is softened or melted, and tends to be in close contact with the rotating roll or difficult to tear and wind. On the other hand, if the heating temperature is too low, a high shearing force is applied to the resin composition and the network structure is destroyed. Moreover, since the fluidity | liquidity of a polymer is low, a sheet | seat is not fully thinned but it becomes easy to tear. On the other hand, in the method of the present invention, the heating temperature in stretching or rolling is controlled to an appropriate range. For example, the network structure is reduced in the thickness direction so that the pantograph is folded. Alternatively, high conductivity can be maintained even after the rolling process.

  In the stretching or rolling treatment, the thickness of the thin film after the treatment may be adjusted to about 1 / 1.2 to 1/10 times the sheet before the treatment, for example, 1 / 1.5-1 to 1. / 8 times, preferably 1/2 to 1/5 times, more preferably about 1 / 2.5 to 1 / 4.5 times.

  The stretching treatment may be uniaxial stretching or biaxial stretching. The biaxial stretching may be simultaneous biaxial stretching or sequential biaxial stretching. The draw ratio may be adjusted so that the thickness of the thin film falls within the above range, and can be selected from a range of about 1.1 to 10 times, preferably 1.5 to 5 times, more preferably 2 to 5 times. It is about twice.

  The load of the rolling treatment can be selected from about 100 kN or less, for example, about 0.1 to 100 kN, preferably 0.5 to 50 kN, more preferably about 1 to 30 kN (particularly 2 to 10 kN). If the rolling pressure increases, the shearing force applied to the thick sheet increases, or the volume-specific low efficiency of the thin film tends to increase. Therefore, the load applied to the sheet from the heating roll is preferably small.

  In the rolling process, a drawing process may be applied in the longitudinal direction of the sheet by increasing the winding speed of the winder from the supply speed of the original sheet. The ratio of the winding speed to the supply speed (winding speed / supply speed) is, for example, about 1 to 10 times, preferably 1.5 to 8 times, more preferably 2 to 5 times (particularly 3 to 4.5 times). is there. This ratio can be selected from this range in accordance with the processing temperature and the applied load, and the thickness of the film may be adjusted by adjusting these conditions. In the rolling process, the relationship between the load load and the speed ratio is preferably such that the load ratio is reduced and the speed ratio is increased from the viewpoint that the film thickness can be made uniform and the conductivity can be improved. Furthermore, from the point of making the film thickness uniform and improving the conductivity, a stretching process without applying a load may be used. In particular, a conductive filler having a cavity structure such as ketjen black can maintain high conductivity even after stretching or rolling because the destruction of the cavity structure can be suppressed.

  Further, in the stretching or rolling treatment, a lubricant or a release agent may be applied to the sheet surface in order to improve workability, or a plurality of rolls may be combined.

  The obtained first conductive layer may be annealed by a conventional method in order to release residual strain in the thinned layer. The annealing temperature is, for example, (mp-60) ° C to (mp-5) ° C, preferably (mp-55) ° C to (mp-10), where mp is the melting point of the crystalline resin. More preferably, it is (mp-50) ° C to (mp-20) ° C.

(Second molding step)
In the second conductive layer forming step, the photocurable composition is applied by a conventional method such as a roll coater, an air knife coater, a blade coater, a rod coater, a reverse coater, a bar coater, a comma coater, a dip Examples include a squeeze coater, a die coater, a gravure coater, a micro gravure coater, a silk screen coater method, a dip method, a spray method, and a spinner method. Of these methods, the bar coater method and the gravure coater method are widely used. If necessary, the coating solution may be applied a plurality of times.

  When the photocurable composition contains an organic solvent, it may be dried as necessary after coating. The drying may be performed at a temperature of, for example, 30 to 150 ° C, preferably 40 to 100 ° C, more preferably about 50 to 70 ° C.

  As a method of irradiating the photocurable composition with light, a method of irradiating light energy rays such as radiation (gamma rays, X-rays, etc.), ultraviolet rays, visible rays, electron beams (EB) can be used. Of these methods, the method of irradiating with ultraviolet rays and electron beams is preferable.

In the method of irradiating ultraviolet rays, as the light source, for example, in the case of ultraviolet rays, a Deep UV lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a halogen lamp, a laser light source (helium-cadmium laser, excimer laser, etc.) Light source) or the like. The amount of irradiation light (irradiation energy) varies depending on the thickness of the coating film, but may be, for example, about 50 to 10,000 mJ / cm ² , preferably 70 to 7000 mJ / cm ² , and more preferably about 100 to 5000 mJ / cm ² .

  As a method of irradiating an electron beam, a method of irradiating an electron beam with an exposure source such as an electron beam irradiation apparatus can be used. The irradiation amount (dose) varies depending on the thickness of the coating film, but is, for example, about 1 to 200 kGy (gray), preferably about 10 to 180 kGy, and more preferably about 30 to 150 kGy (particularly about 50 to 120 kGy). The acceleration voltage is, for example, about 10 to 1000 kV, preferably about 50 to 500 kV, and more preferably about 100 to 300 kV.

  In addition, you may perform irradiation of an electron beam in inert gas (for example, nitrogen gas, argon gas, helium gas etc.) atmosphere as needed.

  In the present invention, the method of irradiating with an electron beam is particularly preferred because polymerization can be performed without using a polymerization initiator and a cured product having high weather resistance can be produced.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. Evaluation of the characteristics of the compounding components used in Examples and Comparative Examples and the conductive composite films obtained in Examples and Comparative Examples was measured by the following method.

[specific gravity]
Based on JIS K7112, specific gravity was calculated | required from the sample density measured using the electronic hydrometer ("Electronic Densometer SD-200L" by Alpha Mirage Co., Ltd.). In addition, in a bulky sample or the like, when a sample shape appropriate for measurement could not be obtained, the sample was cut out after being previously formed by hot pressing.

[Melt flow rate (MFR) and melt tension]
MFR (g / 10 minutes) of a resin composition (for example, pellets) prepared by melt kneading is based on JIS K7210, using a capillary rheometer (“Capillograph 1D” manufactured by Toyo Seiki Seisakusho) The measurement was performed under the conditions of 230 ° C. and 21.2 N load. Moreover, the melt tension of 200 degreeC and 240 degreeC of the said composition was also measured using the same apparatus. The melt tension was measured under the measurement conditions of extrusion speed: 0.05 m / min, pulling speed: 3 m / min, capillary diameter: 2 mmφ, land length: 20 mm.

[Melting point / Glass transition temperature]
The melting point (mp) and glass transition temperature (Tm) of a resin composition (for example, pellets) prepared by melt kneading were measured. The measurement was performed by a normal thermal analysis method using a differential scanning calorimeter (DSC) (trade name “Q2000” manufactured by TA Instruments Inc.).

[Thickness and uniformity of first conductive layer]
Using a micrometer ("Digimatic Micrometer MDC25MJ" manufactured by Mitutoyo Co., Ltd.), the film was measured at 10 points or more at 25 mm intervals in the film width direction (TD), and the film flow direction (MD) The measurement was performed at 10 points or more at intervals of 25 mm, and the arithmetic average value was obtained from the measured values of 20 points or more in total. Similarly, the uniformity (or stability) of the thickness is 1 m in the flow direction (MD) at the center of the film, and the thickness is measured at intervals of 50 mm. The average value of 5 points was calculated as thickness variation ratio = (maximum average value / minimum average value). The smaller the ratio, the more stable the film thickness.

[Conductivity (volume resistivity)]
A seal with a Φ3 mm hole was attached to both sides of the sample, silver paste was applied, the resistance value (Ω) was measured with a tester, and the volume resistivity (Ω · cm) was calculated according to the following formula.

Volume resistivity (Ω · cm) = resistance (Ω) × area (cm ² ) / thickness (cm).

[Solvent resistance of the first conductive layer]
The film was cut into 100 mm × 100 mm, and the initial weight: A (mg) was measured. Next, the film was completely immersed in tetrahydrofuran (THF) at 25 ° C. and allowed to stand for 24 hours, and then the surface of the film taken out was wiped and dried, and the weight: B (mg) was measured again. Based on the following formula, the weight change rate (weight increase rate) was calculated.

Weight change rate (%) = [(BA) / A] × 100 (%)
◎: Less than ± 1% ○: ± 1% or more and less than ± 5% Δ: ± 5% or more and less than ± 10% ×: ± 10% or more.

[Storage elastic modulus E ′ of second conductive layer]
About the obtained test piece, using a dynamic viscoelasticity measuring apparatus (manufactured by TA Instruments Japan Co., Ltd., RSA-III) under the conditions of a heating rate of 5 ° C./min and a frequency of 10 Hz, The storage elastic modulus (E ′) at 50 ° C. to 250 ° C. was determined.

[Flexibility of first conductive layer or conductive composite film]
The test specimen (reference example is the first conductive layer) is cut into 2 cm × 15 cm strips, subjected to a flexibility test in accordance with JIS K5600, and whether or not a mandrel with a diameter of 10 mm is cracked is checked. It was evaluated with.

○: No cracking or cracking occurred ×: Cracking or cracking occurred.

[Solvent permeability of conductive composite film]
Two pieces of the conductive composite film were cut into a size of 10 cm × 10 cm, and the cured coating film was placed on the outside, and the three directions were each welded by 1 cm in width. From the unwelded portion, 2 g of propylene carbonate was added, and a width of 1 cm was welded and sealed. Furthermore, the welded part was sealed with aluminum tape to obtain a test specimen. The test specimen was placed in a desiccator and allowed to stand at 23 ° C. and 50 Rh%, and the change in weight over time was calculated and evaluated based on the following formula. In this test, if the weight change (%) after 14 days is 0.5% or less, the solvent permeability is excellent.

Weight change rate (%) = {[(weight of specimen immediately after enclosing solvent) − (weight of specimen after 14 days)] / (weight of encapsulated solvent)} × 100
[Ingredients]
(First conductive layer)
Polypropylene: Prime polymer “E-100GPL”, specific gravity 0.90
Polyamide 12: “L1901” manufactured by Daicel Evonik Co., Ltd., specific gravity 1.01
Carbon black: “Denka Black HS-100, manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size 48 nm, BET specific surface area 39 m ² / g, specific gravity 1.9
(Second conductive layer)
Trifunctional acrylate: Pentaerythritol triacrylate, “PETIA” manufactured by Daicel Cytec Co., Ltd.
Ring-containing bifunctional acrylate: Tricyclodecane diacrylate, “IRR214K” manufactured by Daicel-Cytec Co., Ltd.
Bifunctional urethane acrylate: highly weather-resistant urethane acrylate, “EBECRYL8402” manufactured by Daicel-Cytec Co., Ltd.
Bifunctional epoxy acrylate: modified epoxy acrylate, “EBECRYL3708” manufactured by Daicel-Cytec Co., Ltd.
Photopolymerization initiator: hydroxycyclohexyl phenyl ketone, “Irgacure 184” manufactured by BASF Japan Ltd.
Furnace carbon black: Conductive carbon black, average primary particle size 50 nm, BET specific surface area 33 m ² / g, “# 4300” manufactured by Tokai Carbon Co., Ltd.

[Production Example 1 of First Conductive Layer]
68 parts by weight of homopolypropylene as a resin component and 32 parts by weight of carbon black as a conductive filler were blended in a pressure kneader kneader, melt mixed, and further pelletized with a feeder ruder. When the characteristics of the pellet were measured, the specific gravity was 1.08, the melting point (mp) was 166 ° C., and the glass transition temperature (Tm) was −22 ° C.

  The obtained pellets are supplied to a T-die extrusion molding machine, extruded into a sheet shape from an extrusion slit gap of 0.8 mm at an extrusion temperature of 230 ° C., wound at a winding speed of 2.5 m / min, and have a thickness of 140 μm. Sex sheet was obtained. The volume resistivity of this sheet was 8 Ω · cm.

  Next, while unwinding the roll sheet, the roll load is 5 kN between the two heating rolls having a surface temperature of the heating roll of 140 ° C. (thermal stretching temperature difference = composition melting point−heating roll surface temperature = −25 ° C.). Then, while being heated from both sides of the sheet, the film was passed at a feeding speed of 1 m / min and a winding speed of 2.8 m / min to perform a heat stretching process. The obtained first conductive layer has a thickness of 40 μm, a volume resistivity of 8 Ω · cm, a thickness variation ratio of 1.1, a weight change rate of THF of 0.8%, and is smooth and has a thickness variation. There was almost no solvent resistance.

[Production Example 2 of First Conductive Layer]
70 parts by weight of polyamide 12 as a resin component and 30 parts by weight of carbon black as a conductive filler were blended in a pressure kneader kneader, melt mixed, and further pelletized with a feeder ruder. When the characteristics of the pellet were measured, the specific gravity was 1.17, the melting point (mp) was 178 ° C., and the glass transition temperature (Tm) was 50 ° C.

  The obtained pellets were supplied to a T-die extrusion molding machine, extruded into a sheet shape from an extrusion slit gap of 0.8 mm to an extrusion temperature of 220 ° C., and wound up with a winder at a winding speed of 1.6 m / min. A conductive sheet having a thickness of 205 μm was obtained. The volume resistivity of this sheet was 80 Ω · cm.

  Next, the sheet was processed in the same manner as in Production Example 1 except that the surface temperature of the heating roll was changed to 150 ° C. (thermal stretching temperature difference = composition melting point−heating roll surface temperature = −28 ° C.) while rewinding the roll sheet. While being heated from both sides, a heat stretching treatment was performed to obtain a conductive film. The obtained first conductive layer has a thickness of 90 μm, a volume resistivity of 67 Ω · cm, a thickness fluctuation ratio of 1.3, a weight change ratio of 9% by THF, and is smooth and has almost no thickness fluctuation. It was excellent in solvent resistance.

[Examples 1 and 2 (Production Examples 1 and 2 of the second conductive layer)]
The acrylate was weighed in a ratio of Table 2 in a 150 ml lidded container and dissolved in a mixed solvent of methyl ethyl ketone (MEK) and toluene (TOL) [MEK / TOL = 50/50 (weight ratio)]. Carbon black was added to this solution, and a dispersion composition was prepared using a self-revolving mixing deaerator (“ARE-250” manufactured by Shinkey Co., Ltd.).

  The obtained dispersion composition was coated on a release paper with a bar coater to a thickness of about 50 μm and dried at 60 ° C. The dried composition was irradiated with an electron beam having an acceleration voltage of 150 kV and a dose of 100 kGy in a nitrogen atmosphere to prepare a cured coating film (second conductive layer). The storage elastic modulus of the second conductive layer obtained by peeling the release paper was evaluated.

  Furthermore, the dispersion composition was applied to the thickness of about 10 μm on the first conductive layer obtained in Production Example 1 or 2, and dried at 60 ° C. The dried composition was irradiated with an electron beam having an acceleration voltage of 150 kV and a dose of 100 kGy in a nitrogen atmosphere to prepare a cured coating film (second conductive layer). The obtained conductive composite film was evaluated for flexibility, solvent permeability, and conductivity.

  These results are shown in Table 1. As Reference Examples 1 and 2, the characteristics of the first conductive layer alone are shown in Table 1.

  The conductive composite films of the examples are flexible, have low solvent permeability, and have high conductivity. On the other hand, the conductive film of the reference example has a solvent permeability of 95% by weight or more, and has a high solvent permeability.

  The conductive composite film of the present invention is used in various fields where conductivity and solvent resistance are required and is used in contact with a solvent, for example, an electronic component, a semiconductor element, a storage container for a semiconductor wafer, a gasoline tank, an electronic -It can be used as a material for flooring and wall materials in electric equipment and semiconductor manufacturing factories, and various battery members (for example, members such as electric double layer capacitors and lithium ion batteries).

Claims (16)

  A photoconductive composition comprising a first conductive layer formed of a crystalline resin composition containing a crystalline resin and a first carbon-based conductive filler, and a photocurable resin and a second carbon-based conductive filler A conductive composite film in which a second conductive layer formed of the cured product is laminated.   The conductive composite film according to claim 1, wherein the first and second carbon-based conductive fillers are conductive carbon black.   The conductive composite film according to claim 1 or 2, wherein the ratio (weight ratio) between the crystalline resin and the carbon-based conductive filler is the former / the latter = 90/10 to 55/45.   The conductive composite film according to claim 1, wherein the crystalline resin is a polypropylene resin and / or a polyamide resin.   The conductive composite film according to any one of claims 1 to 4, wherein the photocurable resin contains a trifunctional or higher polyfunctional vinyl compound and a monofunctional and / or bifunctional vinyl compound.   The conductive composite film according to claim 5, wherein the bifunctional vinyl-based compound contains a chain aliphatic bifunctional (meth) acrylate.   The conductive composite film according to claim 6, wherein the bifunctional vinyl compound further includes a ring-containing bifunctional (meth) acrylate having an aliphatic ring and / or an aromatic ring.   The conductive composite film according to any one of claims 1 to 7, wherein the polyfunctional vinyl compound is a 3-6 functional (meth) acrylate.   The conductive composite film according to any one of claims 1 to 8, wherein the photocurable composition is an electron beam curable composition and does not substantially contain a polymerization initiator.   The thickness of the first conductive layer is 1 to 200 μm, the thickness of the second conductive layer is 1 to 100 μm, and the thickness ratio between the first conductive layer and the second conductive layer is the first conductive layer. The second conductive layer is 1/1 to 20/1. The conductive composite film according to any one of claims 1 to 9.   The volume specific resistivity of the first conductive layer is 0.1 to 1500 Ω · cm, and the volume specific resistivity of the second conductive layer is 1 to 1000 Ω · cm. Conductive composite film.   The conductive composite film according to claim 1, wherein the weight change rate of the first conductive layer after being immersed in tetrahydrofuran at 25 ° C. for 24 hours is 2% by weight or less.   In the dynamic viscoelasticity test measured from −50 ° C. to 250 ° C. under conditions of a temperature rising rate of 5 ° C./min and a frequency of 10 Hz, the storage elastic modulus E ′ in the rubber-like region of the second conductive layer is 200 to 2000 MPa. The conductive composite film according to claim 1.   A molding step of a first conductive layer in which a crystalline resin composition is extruded and then stretched or rolled while heating the obtained sheet, and a photocurable composition on the obtained first conductive layer The manufacturing method of the conductive composite film of Claim 1 including the shaping | molding process of the 2nd conductive layer which light-irradiates and forms a hardened | cured material after apply | coating.   In the molding step of the first conductive layer, after the extrusion molding of the crystalline resin composition to form a sheet having a thickness of 50 to 500 μm, when the melting point of the crystalline resin is mp, (mp-40) The production method according to claim 14, wherein the obtained sheet is stretched or rolled while being heated at a temperature of from ° C to (mp-5) ° C.   The manufacturing method of Claim 14 or 15 which forms a hardened | cured material by irradiating an electron beam to a photocurable composition in the formation process of a 2nd conductive layer.