JP7473763B2 - Conductive hot melt adhesive composition and laminate - Google Patents

Description

The present invention relates to a hot melt adhesive composition that can easily and firmly bond conductive adherends, such as silver, stainless steel, and porous materials such as hydrated wood, while maintaining electrical conductivity between the materials.

In recent years, with the rapid advancement of information technology, the development of devices that can obtain information more accurately, for a long time, and with less power consumption is being actively carried out both in Japan and overseas. In particular, the progress of sensor technology has been tremendous, and by installing sensors in all sorts of places, it is possible to obtain information that was previously difficult to handle or that had to rely on on-site skilled techniques with high accuracy and semi-permanently, and the improvement of sensor attachment and fixing technology has made it possible to obtain information easily.
In this context, there is a demand for a conductive adhesive composition that can easily and firmly bond conductive materials together while maintaining electrical continuity. With technological advances in the electronics field, modularization of electronic materials is progressing, and conductive adhesives are indispensable in such fields.
In addition, such a conductive adhesive composition can be firmly attached to clothing, making it possible to use it as a biosensor. However, at present, there is no commercially available hot melt adhesive composition that can be easily attached and has both high electrical conductivity and adhesive strength.

JP 2001-200225 A JP 2002-155261 A

The object of the present invention is to provide a conductive hot melt adhesive that can easily and firmly bond adherends together while exhibiting high electrical conductivity.

As a result of extensive research into solving the above problems, the inventors discovered that the hot melt adhesive composition shown below can provide simple and strong adhesion, leading to the completion of the present invention.

That is, the present invention relates to a conductive hot melt adhesive composition comprising a thermoplastic resin and a conductive filler, the conductive hot melt adhesive composition having a volume resistivity of less than 1 x 10 ³ Ωcm and a modulus of elasticity of the conductive hot melt adhesive composition of less than 5 MPa at 25°C.

The present invention also relates to the conductive hot melt adhesive composition, characterized in that the conductive filler is at least one selected from the group consisting of graphite, carbon black, carbon nanotubes, graphene, graphene oxide, silver, copper, tin, zinc, zinc oxide, nickel, manganese, and ITO.

The present invention also relates to the conductive hot melt adhesive composition, characterized in that the conductive filler is at least one selected from the group consisting of graphite, carbon black, carbon nanotubes, graphene, and graphene oxide.

The present invention also relates to the conductive hot melt adhesive composition, characterized in that the content of the conductive filler in the entire composition is 2% by weight or more and 65% by weight or less.

The present invention also relates to the conductive hot melt adhesive composition, characterized in that the thermoplastic resin contains at least one selected from the group consisting of styrene-based thermoplastic resins, polyamide-based thermoplastic resins, polyolefin-based thermoplastic resins, polyester-based thermoplastic resins, polyvinyl chloride-based thermoplastic resins (PVC), ethylene-vinyl acetate-based thermoplastic resins (EVA), and ethylene-propylene-diene-based thermoplastic resins (EPDM).

The present invention also relates to the above-mentioned conductive hot melt adhesive composition, characterized in that the styrene-based thermoplastic resin is a styrene-isoprene-styrene block copolymer (SIS), a hydrogenated styrene- ethylene-propylene -styrene block copolymer (SEPS), a styrene-butylene-styrene block copolymer (SBS), a hydrogenated styrene-ethylene-butylene-styrene block copolymer (SEBS), a styrene- butadiene-isoprene-styrene block copolymer (SBIS), or a hydrogenated styrene-ethylene-ethylene-propylene -styrene block copolymer (SEEPS).

The present invention also relates to the conductive hot melt adhesive composition, which further comprises a tackifier.

The present invention also relates to the above hot melt adhesive composition, further comprising a softener.

The present invention also relates to a laminate that is characterized by being formed by laminating a substrate, the conductive hot melt adhesive composition, and an adherend in that order.

The present invention also relates to the above laminate, characterized in that the substrate is a conductor.

The present invention provides a conductive hot melt adhesive composition that exhibits high electrical conductivity and adhesive strength.

FIG. 1 shows an example of the structure of the laminate of the present invention.

The following describes an embodiment of the present invention.

The conductive hot melt adhesive composition of the present invention is characterized by containing a thermoplastic resin and a conductive filler.

<Conductive filler>
Examples of the conductive filler used in the present invention include metals such as silver, gold, copper, nickel, zinc, zinc oxide, manganese, and aluminum, metal oxides such as tin oxide-doped indium oxide (ITO), tin oxide-doped indium oxide (FTO), tin oxide (IO), and neodymium-barium-indium oxide, organic substances such as polythiophenes, polypyrroles, polyanilines, and oligothiophenes, inorganic insulators such as alumina and glass, and polymers such as polyethylene and polystyrene coated with a conductive substance, and carbon-based substances such as carbon black, graphite, graphene, carbon nanotubes, fullerenes, graphene oxide, and acetylene black, but are not limited to these. These may be used alone or in combination of two or more. The conductive filler is preferably silver or carbon-based.

The shape of the conductive filler may be flake-shaped (scale-shaped), spherical, needle-shaped, fibrous, or dendritic, but is not limited to these. If it is desired to reduce the amount of conductive filler added in order to strengthen the adhesive strength, flake-shaped (scale-shaped) fillers and mixtures of flake-shaped (scale-shaped) fillers with other conductive fillers are preferred. Of these, it is preferable to use spherical or spike-shaped conductive fillers as other mixtures, as this makes it possible to achieve low resistivity with a small amount of addition and also makes it easier to demonstrate electrical conductivity in the thickness direction. Of these, it is preferable to use Ketjen black.

The content ratio of the conductive filler in the entire conductive hot melt adhesive composition is not particularly limited, but from the viewpoint of adhesive strength and electrical conductivity, 40 to 80% by weight is preferable for metals such as silver and gold, and 50 to 70% by weight is more preferable. If it is less than 40% by weight, the electrical conductivity is insufficient, and if it exceeds 80% by weight, the adhesive strength is insufficient, which is not preferable. On the other hand, for carbon-based materials such as carbon black and graphite, 2 to 65% by weight is preferable, and 5 to 40% by weight is more preferable. If it is less than 2% by weight, the electrical conductivity is insufficient, and if it exceeds 60% by weight, the adhesive strength is insufficient, which is not preferable.

<Hot melt adhesive>
The hot melt adhesive composition of the present invention can be obtained by using a hot melt adhesive obtained by heating and mixing a thermoplastic resin, a softener, a tackifier, an antioxidant, and other optional components used as necessary using a roll, a Banbury mixer, a kneader, a melting pot equipped with a stirrer, or a single-screw or twin-screw extruder, or by using a solvent-based adhesive obtained by dissolving in a suitable solvent and stirring and mixing. The hot melt adhesive composition used in the present invention is preferably a hot melt adhesive that does not use a solvent, from the viewpoint of the complication of the process due to the solvent removal and the associated increase in cost, and from the viewpoint of the adverse effect on the global environment due to the use of a solvent. In addition, the hot melt adhesive composition used in the present invention can be used with a thermoplastic resin alone, but it is preferable to include a softener, a tackifier, and an antioxidant from the viewpoint of imparting fluidity, adhesion, and oxidation stability.

<Thermoplastic resin>
The thermoplastic resin may be a so-called hot melt resin, which is a non-curable resin that becomes flowable at high temperatures and returns to a non-flowable state upon cooling, or it may be a curable resin, which undergoes a curing (crosslinking) reaction after the thermoplastic resin is applied to a substrate.

The thermoplastic resin may include one or more selected from the group consisting of thermoplastic resins including polyurethane, acrylonitrile, diene, acrylic, butadiene, polyamide, polyvinyl butyral, olefin, isoprene, butadiene, chloroprene, acrylonitrile, polyester, polyvinyl chloride, styrene, ethylene-vinyl acetate, fluorine, silicone, and copolymers thereof. However, the thermoplastic resin is not limited to these resins. From the viewpoints of durability, weather resistance, heat resistance, and adhesive strength, the thermoplastic resin may more preferably include a styrene-based thermoplastic resin. The thermoplastic resin may be used alone or in combination of two or more types. Furthermore, the thermoplastic resin may be a copolymer formed by linking different monomers.

Styrene-based thermoplastic resins, more specifically styrene-based elastomers, generally have a polystyrene block and a rubber intermediate block, the polystyrene portion forms a physical crosslink (domain) and becomes a crosslinking point, and the intermediate rubber block gives the product rubber elasticity. The intermediate soft segments include polybutadiene (B), polyisoprene (I) and polyolefin elastomers (ethylene propylene, EP), and are divided into linear type and radial type depending on the arrangement with the hard segment polystyrene (S). Among the above-mentioned preferred styrene-based elastomers, the present invention may more specifically include one or more selected from the group consisting of styrene - isoprene - styrene block copolymer (SIS), hydrogenated styrene-ethylene- propylene -styrene block copolymer (SEPS), styrene-butylene-styrene block copolymer (SBS), hydrogenated styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-butadiene-isoprene-styrene block copolymer (SBIS) and hydrogenated styrene -ethylene-ethylene-propylene -styrene block copolymer (SEEPS), but is not limited to these resins.

<Tackifier>
Examples of tackifiers include hydrogenated terpene resins, terpene resins, hydrogenated rosin resins, hydrogenated hydrocarbon resins, epoxy resins, hydrogenated epoxy resins, ketone resins, hydrogenated ketone resins, polyamide resins, hydrogenated polyamide resins, elastomer resins, hydrogenated elastomer resins, phenol resins, hydrogenated phenol resins, petroleum resins, hydrogenated petroleum resins, styrene resins, and hydrogenated styrene resins. These tackifier resins can be used alone or in combination.
Among these, hydrogenated hydrocarbon resins are preferred from the viewpoint of durability. By hydrogenating, the molecular structure does not have conjugated double bonds, so that the hot melt adhesive containing the tackifier is less likely to deteriorate due to light or heat when it is permanently bonded to an adherend, and the adhesive strength can be maintained for 10 years or more.

<Softener>
Examples of the softener include petrolatum, mineral oil, vegetable oil, and animal oil. Examples of the mineral oil include liquid paraffin, paraffin, paraffin-based mineral oil in which the number of carbon atoms in the paraffin chain accounts for 50% or more of the total carbon number, naphthenic mineral oil in which the number of carbon atoms in the naphthenic ring accounts for 30 to 40% by weight of the total carbon number, and aromatic mineral oil in which the number of aromatic carbon atoms accounts for 30% by weight or more of the total carbon number. Vegetable oils and fats: Olive oil, carnauba wax, rice germ oil, corn oil, camellia oil, castor oil, jojoba seed oil, mink oil, eucalyptus leaf oil, and the like. Animal oils and fats: Beeswax, squalane, and honey. Other examples of softening agents include myristic acid, oleic acid, isopropyl myristic acid, zinc myristic acid, octyldodecyl myristate, glycerin triisooctanoate, octyldodecanol, hexyldecanol, diisopropyl adipate, diethyl sebacate, stearic acid, isostearic acid, crotamiton, medium-chain triglyceride, ethylene glycol salicylate, cetyl ethylhexanoate, glycol distearate, cetearyl alcohol, cetanol, cetyl palmitate, ethylhexyl palmitate, isopropyl palmitate, behenyl alcohol, etc. These softening agents can be used alone or in combination.

<Antioxidants>
Examples of the antioxidant include pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, diethyl[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]phosphonate, 4,6-bis(octylthiomethyl)-o-cresol, ethylene bis(oxyethylene)bis[3-(5-t-butyl-4-hydroxy-m-tolyl]propionate, tris(2,4-di-t-butylphenyl)phosphite, and bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite. The phenol-based antioxidant is preferably pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], and the phosphorus-based antioxidant is preferably tris(2,4-di-t-butylphenyl)phosphite.

<Other ingredients>
The hot melt adhesive composition can be appropriately blended with various additives as long as the effect of the present invention is not impaired. For example, from the viewpoint of reducing the cure shrinkage rate, reducing the thermal expansion rate, improving dimensional stability, improving the elastic modulus, adjusting the viscosity, improving strength and improving toughness, curing agents such as polyisocyanate, epoxy resin, polycarbodiimide compound, and organic or inorganic fillers can be blended. Such fillers may be composed of materials such as polymers, ceramics, metals, metal oxides, metal salts, and dyes and pigments. The shape of the filler is not particularly limited, and may be, for example, particulate or fibrous. In addition, in order to adjust the leveling property and coating property with the substrate and improve the adhesiveness, liquid rubber, silane coupling agent, titanate coupling agent, flame retardant, storage stabilizer, antioxidant, metal deactivator, ultraviolet absorber, thixotropy imparting agent, leveling agent, defoamer, dispersion stabilizer, fluidity imparting agent, defoamer, coloring material, etc. may also be added. In addition, a solvent may be included to improve fluidity.

<Conductive hot melt adhesive composition>
The conductive hot melt adhesive composition of the present invention can be produced by blending the above-mentioned hot melt adhesive having the thermoplastic resin as an essential component, a conductive filler as an essential component, and, if necessary, a softener, a tackifier, an antioxidant and other components, and then uniformly dispersing them.

The hot melt adhesive composition and the conductive filler are dispersed by melting the hot melt adhesive composition at a high temperature of 150°C or higher using a kneader, Banbury mixer, single-screw extruder, twin-screw extruder, three-roll mill, or two-roll mill, adding the conductive filler, and then melt-kneading the mixture. However, the mixture may be kneaded at a temperature of 150°C or lower if the method allows the hot melt adhesive composition and the conductive filler to be melt-kneaded. Alternatively, the hot melt adhesive composition is dissolved in a solvent, the conductive filler is added, and the mixture is dispersed by a planetary stirring method, a three-roll mill method, a two-roll mill method, a Scandex method, a bead mill method, a jet mill method, a starburst method, or a sand mill method. The solvent used is not particularly limited as long as it dissolves the thermoplastic resin and the hot melt adhesive composition. However, other dispersion methods may be used as long as they do not deteriorate the physical properties.

<Laminate>
The conductive hot melt adhesive composition of the present invention has a conductive hot melt adhesive composition layer formed by applying or printing the conductive hot melt adhesive composition on one side of a substrate, and can be used as a sheet-type electrode.
The coating and printing method of the conductive hot melt adhesive composition is not particularly limited. Coating methods include slot spray coating, omega coating, spiral coating, control seam coating, slot spray coating, dot coating, hot melt applicator coating, hot melt coater coating, blade coat coating, dip coating, gravure coat coating, curtain spray coating, bead coating, and hot melt roll coater spin coat coating. Printing methods include inkjet printing, spray printing, roll coat printing, doctor roll printing, doctor blade printing, curtain coat printing, slit coat printing, screen printing, reverse printing, push coat printing, and slit coater printing. Drying conditions when a solvent is used are not particularly limited, and include those using hot air drying, infrared rays, and reduced pressure methods. Drying conditions vary depending on the film thickness and the selected organic solvent, but hot air heating at about 60 to 200 ° C. is usually used. The thickness of the conductive hot melt composition is preferably 100 to 300 μm. The conductive hot melt composition layer can also be crosslinked by heating or irradiating with ultraviolet light.

<Substrate>
The substrate is selected from the group consisting of a resin sheet, paper, and an aluminum sheet (aluminum foil). For example, the resin sheet may be a resin sheet formed from a resin such as a polyester resin such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), a polycarbonate resin, a polyarylate resin, an acrylic resin, a polyphenylene sulfide resin, a polystyrene resin, a vinyl resin, a vinyl chloride resin, a polyimide resin, an epoxy resin, a polyolefin resin such as polyethylene, polypropylene, or polynorbornene. In addition, the substrate may be a laminate in which a metal is laminated on these sheets, for example, a laminate in which a metal is laminated on a polyethylene terephthalate (PET) sheet. In addition, since the substrate may be deformed by heat, a substrate with high heat resistance such as a polyimide sheet, a polynaphthalene sheet, a propylene sheet, or a silicone resin sheet, or a substrate with improved heat resistance due to filler filling, is preferred.

<Adhesion process>
Next, the conductive hot melt adhesive composition and the substrate are placed on the adherend, and the conductive hot melt composition is melted on the adherend using, but not limited to, an iron or an IH heating device to bond the conductive hot melt adhesive composition to the adherend, thereby manufacturing the conductive hot melt adhesive composition. The substrate may be a conductive material, a non-conductive material, or a combination thereof, but is not particularly limited thereto. The adherend may be silver, stainless steel, copper, iron, aluminum, concrete, mortar, slate, wood, ceramic, glass, cork, paper, minerals, non-ferrous metals, polymers, human skin, or the like, but is not particularly limited thereto.

<Other laminates>
Other laminate components may include a mesh layer between the composition and the substrate to improve the strength of the laminate.

<Resistivity>
When forming a conductive hot melt adhesive composition, it is preferable to set the volume resistivity to a value of less than 1×10 ³ Ω·cm. The reason for this is that if the volume resistivity of the conductive hot melt adhesive composition is within this range, it can be imparted with suitable conductivity when made into a conductive hot melt adhesive sheet. Therefore, it is more preferable to set the volume resistivity of the conductive hot melt adhesive composition to a value of less than 1×10 ³ Ω·cm, and even more preferable to set the volume resistivity to a value of less than 1×10 ¹ Ω·cm. The detailed method for measuring the volume resistivity will be specifically described in the examples.

<Elastic modulus>
The preferred range of the elastic modulus of the composition of the present invention is less than 5 MPa, more preferably less than 1 MPa. The reason for this is that if the elastic modulus of the conductive hot melt adhesive composition is within this range, when it is made into a conductive hot melt adhesive sheet, it can follow the complex shape of the adherend and can exhibit a more suitable adhesive force. The detailed method for measuring the elastic modulus will be specifically described in the examples.

<Adhesive strength>
The adhesive strength value of the conductive hot melt adhesive composition varies depending on the adherend, but the preferred range is 2 N/25 mm or more and less than 10 N/25 mm, and more preferably 10 N/25 mm or more. The detailed method for measuring the adhesive strength will be specifically described in the examples.

The present invention will be described in detail below with reference to examples. However, these examples are merely one aspect of the present invention, and the present invention is not limited to these examples. In the tables, "parts" means "parts by weight" and "%" means "% by weight."

[Preparation of hot melt adhesive]
(Production Examples 1 to 29)
A stainless steel beaker equipped with a stirrer was charged with 1:10 parts of a softener as a softener, 1:40 parts of SIS as a thermoplastic resin, 1:50 parts of a tackifier as a tackifier, and 1:1 part of an antioxidant, and the mixture was heated to a temperature range of 150° C. to melt. The mixture was then stirred to obtain a uniform molten solution, which was then cooled to obtain hot melt adhesive 1.
Hot melt adhesives 2 to 29 were prepared in the same manner as for hot melt adhesive 1, except that the raw materials and composition ratios were changed as shown in Table 1.

[Adjustment of conductive filler]
(Production Examples 30 to 50)
The filler powders shown in Table 2 were mixed by hand to obtain conductive fillers 1 to 21.

[Preparation of conductive hot melt adhesive]
A hot melt adhesive composition 1 (70 parts) and a conductive filler composition 1 (30 parts) were kneaded in a kneader equipped with a stirrer at 150° C. for 3 hours to obtain a conductive hot melt adhesive composition 1.
Conductive hot melt adhesives 2 to 65 were prepared in the same manner as for preparing the conductive hot melt adhesive 1, except that the type and compounding ratio of the hot melt adhesive and the conductive filler were changed as shown in Table 3.

The abbreviations for the thermoplastic resin, tackifier, softener, and other components listed in Table 1 are shown below.

<Thermoplastic resin>
SEBS1: Kraton Corporation Product name: G1652
・SEBS2: Kraton Corporation Product name: G1726
・SEBS3: Kraton Corporation Product name: G1650
・SEBS4: Kraton Corporation Product name: G1651
・SBS1: Kraton Corporation Product name: D0243
・SBS2: Clayton Corporation Product name: D4433
SIS1: Clayton Corporation Product name: D1117
SIS2: Clayton Corporation Product name: D1114
・SEPS1: Kuraray Co., Ltd. Product name: SEPTON 2063
・SEPS2: Kuraray Co., Ltd. Product name: SEPTON 2005
・SEPS3: Kuraray Co., Ltd. Product name: G1730
Olefin 1: Ube Maruzen Polyethylene Co., Ltd. Product name: UBE BOND F1100

Olefin 2: Toyobo Co., Ltd. Product name: PMA H3000P
Polyamide 1: Henkel Corporation Product name: PA6858
Polyamide 2: Arkema Co., Ltd. Product name: Platamide M1276
Polyester 1: Toyobo Co., Ltd. Product name: Vylon 200
・PVC1: Mitsubishi Chemical Corporation Product name: Sunplane FG40EA
・EVA1: Mitsui DuPont Polychemicals Co., Ltd. Product name: Evaflex V5733
EPDM1: JSR Corporation Product name: EP96

<Tackifier>
Tackifier 1: Arakawa Chemical Industries, Ltd. Product name: P-100
Tackifier 2: Harima Chemical Co., Ltd. Product name: Haritack F
Tackifier 3: Yasuhara Chemical Co., Ltd. Product name: YS Polystar T30
Tackifier 4: Arakawa Chemical Industries, Ltd. Product name: P-90

<Softener>
Softener 1: Idemitsu Kosan Co., Ltd. Product name: Diana Process Oil NS90S
Softener 2: Idemitsu Kosan Co., Ltd. Product name: Diana Process Oil PW90
Softener 3: Nippon Sun Oil Co., Ltd. Product name: SUNPURE N100

<Other ingredients>
Antioxidant 1: BASF Japan Ltd. Product name: Irganox 1010
Liquid rubber 1: Kuraray Co., Ltd. Product name: Kuraray LIR290

The abbreviations for the conductive fillers listed in Table 2 are as follows.
Filler 1: SEC Carbon Co., Ltd. Product name: SGO-10 (flake graphite)
Filler 2: CABOT Corporation Product name: VULCAN XC-72R (carbon black)
Filler 3: Lion Specialty Chemicals Co., Ltd. Product name: EC300J (Ketjen Black)
Filler 4: Lion Specialty Chemicals Co., Ltd. Product name: EC200L (Ketjen Black)
Filler 5: Lion Specialty Chemicals Co., Ltd. Product name: EC600JD (Ketjen Black)
Filler 6: Nippon Graphite Industry Co., Ltd. Product name: CMX-100 (graphite)
Filler 7: Nippon Graphite Industry Co., Ltd. Product name: LEP (graphite)
Filler 8: Hyperion Catalysis International, Inc. Product name: Hyperion BN (carbon nanotubes)
Filler 9: i-Tech Co., Ltd. Product name: iGurafen-α (graphene)
Filler 10: Fukuda Metal Foil and Powder Co., Ltd. Product name: Ag-XF301S (silver)
Filler 11: Taimei Chemical Industry Co., Ltd. Product name: Taimicron TM-DA (alumina)

Next, the following experiments were carried out using the obtained compositions (Examples 1 to 65, Comparative Examples 1 to 5).
However, Examples 33, 58, 59, and 61 to 65 are reference examples.

1. Measurement of volume resistivity The compositions obtained in Composition Examples 1 to 65 and Comparative Examples 1 to 5 were heated and pressed with a press plate to form sheets consisting of a laminate of the composition and a plastic film, and the laminates were cut into pieces of 1.5 cm x 3 cm, and the volume resistivity of the composition layer was measured by a four-probe method using a low-resistance resistivity meter (Loresta GX MCP-T700, manufactured by Mitsubishi Chemical Analytech Co., Ltd.). Evaluation was performed in two stages.
If rated as "○", the claim is met.
◯: Volume resistivity is less than 1×10 ³ Ωcm ×: Volume resistivity is 1×10 ³ Ωcm or more

2. Measurement of elastic modulus The tensile test of the conductive hot melt adhesive was performed using a tensile tester EX-SX manufactured by Shimadzu Corporation. The measurement method was as follows: the compositions obtained in Composition Examples 1 to 65 and Comparative Examples 1 to 5 were cut into 5 mm x 1 mm x 24 mm to be used as measurement samples, and the measurement samples were placed at 25°C, with a crosshead speed of 50 mm/min. The crosshead displacement and the load history immediately before breakage were measured, and the longitudinal strain of the measurement samples was measured using a strain gauge. The elastic modulus was calculated from the obtained stress-strain diagram.
◎: Elastic modulus is less than 1 MPa ○: Elastic modulus is 1 MPa or more and less than 5 MPa ×: Elastic modulus is 5 MPa or more

3. Measurement of adhesive strength The adhesive strength of the conductive hot melt adhesive was measured using a tensile tester EX-SX manufactured by Shimadzu Corporation. The measurement samples were prepared by attaching sheets of the conductive hot melt adhesive compositions 1 to 65 and comparative examples 1 to 5, each of which was made of a laminate of a composition having a thickness of 200 um and a polyimide film, to various adherends of 7 cm x 7 cm (in the case of concrete, the surface had been previously treated with a grinder), and pressing a press plate of 2 cm x 7 cm size from above at a temperature of 200 ° C. while applying a pressure of 0.1 MPa for 1 minute to adhere the sheets. After heating, the samples were left to stand for 24 hours until they returned to room temperature, and used as the measurement samples. The measurement method was to adjust the measurement sample in which the composition sheet was attached to the adherend to a width of 25 mm, and the adhesive strength was calculated from the load when the edge of the sheet was peeled off at an angle of 90 degrees at a speed of 50 mm/min. The evaluation was performed in three stages as follows.
◎: Adhesive strength is 10N or more ○: Adhesive strength is 2N or more but less than 10N ×: Adhesive strength is less than 2N Grinder used: Monotaro Slim Disc Grinder (MRO-100DG)
Heat press machine used: TP-701B

The results in Table 3 show that the laminates formed using the compositions prepared in Examples 1 to 65 have very good adhesion and volume resistivity compared to the comparative laminates formed using the conductive hot melt adhesive compositions prepared in Comparative Examples 1 to 5. In other words, it was found that the compositions prepared in Examples 1 to 65 can be more suitably used to form conductive hot melt adhesive laminates compared to the compositions prepared in Comparative Examples 1 to 5.

Claims (6)

A conductive hot melt adhesive composition comprising a thermoplastic resin and a conductive filler, the volume resistivity being less than 1×10 ³ Ωcm, and the elastic modulus of the conductive hot melt adhesive composition being less than 5 MPa at 25° C.;
Further, it contains a softener,
The thermoplastic resin comprises a styrene-based thermoplastic resin, and the conductive hot melt adhesive composition contains 25 to 70 mass % of the conductive filler . The conductive hot melt adhesive composition according to claim 1, characterized in that the styrene-based thermoplastic resin is a styrene-isoprene-styrene block copolymer (SIS), a hydrogenated styrene-ethylene-propylene-styrene block copolymer (SEPS), a styrene-butylene-styrene block copolymer (SBS), a hydrogenated styrene-ethylene-butylene-styrene block copolymer (SEBS), a styrene-butadiene-isoprene-styrene block copolymer (SBIS), or a hydrogenated styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS). 3. The conductive hot melt adhesive composition according to claim 1 , further comprising a tackifier. 4. The conductive hot melt adhesive composition according to claim 1, wherein the content of the softener in the entire composition is 3.0% by weight or more and 34.7% by weight or less . A laminate comprising a substrate, the conductive hot melt adhesive composition according to any one of claims 1 to 4 , and an adherend laminated in that order. 6. The laminate according to claim 5 , wherein the substrate is an electrical conductor.