HK1258044B - Conductive sheet - Google Patents

Description

Conductive sheet

The present application is a divisional application of an invention patent application having an application date of 2013, 9 and 18, an application number of 201380048563.1, and an invention name of "conductive sheet".

Technical Field

The present invention relates to a conductive sheet suitable for obtaining, for example, a case where a display surface control surface of a display surface control panel is electrically connected to a back surface thereof.

Background

As a conventional electromagnetic wave sealing agent, a conductive sheet having a conductive adhesive layer provided on one surface of a metal foil such as aluminum or copper has been proposed (patent document 1). In order to prevent such a conductive sheet from short-circuiting due to contact with another conductor, the following improvements are made: by laminating a polyethylene terephthalate (PET) film as an insulating resin layer on the surface of the conductive sheet on which the conductive adhesive layer is not formed, insulation is provided to one surface of the conductive sheet. In addition, a release film is attached to the conductive adhesive layer to improve the handling property (ハンドリング property).

In recent years, however, a display surface control panel (so-called touch panel) is used in a smart phone, a portable game machine, a ticket vending machine, or the like, and a conductive sheet is used to obtain conduction from the display surface control panel to the back surface thereof. In order to prevent such a conductive sheet from being short-circuited by being inadvertently brought into contact with another conductor such as a metal case, it is also proposed to provide insulation on one surface by laminating an insulating resin film on the one surface. When such a conductive sheet is electrically connected from the display surface control surface of the display surface control panel to the back surface thereof, it is attempted to wrap the outer edge portion of the display surface control panel so that the insulating resin film of the conductive sheet is positioned outside. In this case, in order to improve the quality of an image to be recognized by the display surface control panel or to prevent a decrease in image recognition, attempts have been made to make the insulating resin film itself black or to form a black printed layer on the insulating resin film so that the insulating resin film of the conductive sheet is a black frame.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 62-227985.

Disclosure of Invention

Problems to be solved by the invention

However, when the conductive sheet of patent document 1 is passed through a coater or a release film is peeled off from the conductive sheet, the conductive sheet is likely to be curled because the metal layer is more likely to be plastically deformed and the PET film is more likely to be elastically deformed than the PET film. Further, when the conductive sheet is attached to the display surface control panel so as to wrap the outer edge portion of the display surface control panel, a step difference (difference in plane) between the conductive sheet and the attached portion or followability of the shape of the corner portion is not sufficient, and therefore, there is a problem that the conductive sheet is easily peeled off and a necessary shape retention property cannot be obtained.

The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide a conductive sheet, which is formed by laminating a conductive adhesive layer on one surface of a base substrate (ベース substrate) and a light-shielding insulating layer on the other surface of the base substrate, with good curling resistance, good shape stability, and good shape-following properties.

Means for solving the problems

The inventor finds that: the above object can be achieved by using a laminate in which metal layers of the same kind are laminated on both sides of a resin film as a base substrate of a central portion of a conductive sheet in a thickness direction, and the present invention has been completed.

That is, the present invention provides a conductive sheet in which a conductive adhesive layer is laminated on one surface of a base substrate and a light-shielding insulating layer is laminated on the other surface of the base substrate, wherein the base substrate has a structure in which metal layers of the same kind are formed on both surfaces of a resin film.

In this case, the surface resistance value of the light-shielding insulating layer surface of the conductive sheet at the insulating level is preferably 1.0 × 10⁸The gloss is preferably 80% or less and the optical density is preferably 1 or more at a light-shielding level of not less than Ω/□.

The present invention also provides an image display module comprising a display panel control panel and an image display panel controlled by the display panel control panel, wherein the display panel control panel is connected by a conductive sheet of the present invention, in which a front electrode provided at a front outer edge portion of the display panel control panel and a rear electrode provided at a rear outer edge portion are disposed so as to wrap an outer edge portion of the display panel control panel.

Effects of the invention

The conductive sheet of the present invention, in which a conductive adhesive layer is laminated on one surface of a base substrate and a light-shielding insulating layer is laminated on the other surface of the base substrate, uses a substrate having a structure in which metal layers of the same kind are formed on both surfaces of a resin film as the base substrate. Therefore, even when the conductive sheet is stretched, the metal layers on both sides of the resin film exhibit the same elongation, and therefore the occurrence of curling can be greatly suppressed. Further, since the metal layers are disposed on both sides of the insulating film, the insulating film can be attached to a shape which changes due to a curved surface, a bent portion (corner portion), or the like with good shape-following properties, and has excellent shape-retaining properties.

When the insulating property of the light-shielding insulating layer surface of the conductive sheet reaches 1.0X 10⁸The surface resistance value of Ω/□ or more can suppress the occurrence of short circuit due to contact with another conductor. In addition, when the light-shielding property level reaches a glossiness of 80% or less and an optical density of 1 or more, a grid-like black frame may be provided at the outer edge portion of the display surface control panel, and the visibility of an image observed through the display surface control panel may be greatly improved.

Drawings

FIG. 1 is a cross-sectional view of a conductive sheet of the present invention;

FIG. 2 is a cross-sectional view of a conductive sheet of the present invention;

fig. 3 is a cross-sectional view of the conductive sheet of the present invention.

Detailed Description

Hereinafter, the conductive sheet of the present invention will be described in detail with reference to the drawings.

Fig. 1 is a cross-sectional view of a conductive sheet 100 according to the present invention, in which the conductive sheet 100 has a structure in which a conductive adhesive layer 20 is formed on one surface of a base substrate 10 and a light-shielding insulating layer 30 is formed on the other surface.

< basic substrate >

The conductive sheet 100 of the present invention has the following features: the base substrate 10 has a structure in which the same kind of metal layers 2 and 3 are laminated on both surfaces of the resin film 1. This can significantly suppress the occurrence of curling in the conductive sheet, and can impart good shape-following properties and shape stability to the conductive sheet.

As the resin film 1 constituting the base substrate 10, a resin film used as a base film of a conductive sheet can be preferably used. Examples of such resin films include polyester films, polyolefin films, polyamide films, polyurethane films, and polystyrene films. Among them, a polyester film, particularly a polyethylene terephthalate film, can be preferably used from the viewpoint of easiness of obtaining, mechanical strength, heat resistance, cost, rust resistance, and the like.

The thickness of the resin film 1 constituting the base substrate 10 is preferably 5 to 20 μm, and more preferably 7 to 15 μm, in order to maintain the mechanical strength of the conductive sheet and ensure good shape-following properties and shape stability.

As the metal layers 2 and 3 constituting the base substrate 10, metal layers used in conventional conductive sheets can be used. Examples of such metal layers 2 and 3 include aluminum, copper, nickel, gold, and silver. Among them, aluminum is preferably used in view of easiness of obtaining, mechanical strength, heat resistance, cost, rust prevention, and the like.

In order to maintain the mechanical strength of the conductive sheet and ensure good shape-following properties and shape stability, the thicknesses of the metal layer 2 on the conductive adhesive layer 20 side and the metal layer 3 on the light-shielding insulating layer 30 side are preferably 5 to 20 μm, and more preferably 7 to 15 μm, respectively.

From the viewpoint of both shape followability and shape retainability, the ratio of the thickness [ Mt1] of the metal layer 2 on the conductive adhesive layer 20 side to the thickness [ Bt ] of the resin film 1 to the thickness [ Mt2] of the metal layer 3 on the light-shielding insulating layer 30 side is preferably [ Mt1 ]: [ Bt ]: [ Mt2] ═ 0.25 to 4: 1: 0.25 to 4, more preferably 0.4 to 2.4: 1: 0.4 to 2.4.

The metal layers 2, 3 may be formed on the resin film 1 using a conventional method. Examples thereof include: a method of laminating a metal foil as a metal layer on the resin film 1 via an adhesive layer (not shown) formed of a polyester adhesive containing an isocyanate-based crosslinking agent or a dry adhesive such as a polyurethane adhesive; a method of forming the metal layers 2 and 3 by performing electroless metal plating and electrolytic metal plating on both surfaces of the resin film 1; or a method of laminating the metal layers 2 and 3 on both surfaces of the resin film 1 by a vacuum vapor deposition method. Among them, a method of laminating a metal layer via an adhesive layer is preferably used from the viewpoint of high productivity and low production cost.

In addition, the resin film 1 constituting the base substrate 10 is preferably 15 to 100 ppm/DEG C, and more preferably 20 to 70 ppm/DEG C, because if the linear expansion coefficient [ ppm/DEG C ] is too large, curling is likely to occur, and if it is too small, the laminated structure tends to be unstable in a thermal environment, and thus interlayer peeling may occur.

The linear expansion coefficient [ ppm/DEG C ] of the metal layers 2 and 3 is preferably 12 to 25 ppm/DEG C, and more preferably 16 to 23 ppm/DEG C, from the viewpoint of stability of the laminated structure with the resin film 1.

If the difference between the linear expansion coefficient of the resin film 1 and the linear expansion coefficients of the metal layers 2 and 3 is too large, curling tends to easily occur, and therefore, it is preferably 40 ppm/c or less, and more preferably 25 ppm/c or less.

The tensile modulus [ GPa ] of JIS K7113 of the resin film 1 constituting the base substrate 10 tends to curl easily when the tensile modulus [ GPa ] is too small, and tends to lose the shape-following property when the tensile modulus [ GPa ] is too large, so the tensile modulus is preferably 0.3-15 GPa, and more preferably 2-7 GPa.

Further, the tensile modulus [ GPa ] of JIS K7113 of the metal layers 2 and 3 tends to curl easily when it is too small, and tends to deteriorate shape-following properties when it is too large, and therefore, it is preferably 45 to 200GPa, and more preferably 75 to 130 GPa.

If the difference in tensile modulus between the resin film 1 constituting the base substrate 10 and the metal layers 2 and 3 in JIS K7113 is too large, curling tends to occur easily, and therefore, it is preferably 100GPa or less, more preferably 80GPa or less.

< light-shielding insulating layer >

The light-shielding insulating layer 30 constituting the conductive sheet 100 of the present invention is a layer for imparting light-shielding properties and insulating properties to the conductive sheet 100. Here, if the insulation level of the light-shielding insulating layer 30 surface of the conductive sheet 100 is too low, short circuit may occur, and therefore the surface resistance value is preferably 1.0 × 10⁸Omega/□ or more, more preferably 1.0X 10¹⁰Omega/□ or more.

In addition, regarding the level of light-shielding property of the light-shielding insulating layer 30, in order to improve the visibility of an image, the glossiness of JIS Z8741 (incident angle 60 °) is preferably 80% or less, more preferably 40% or less, and the optical density of JIS K7605 is preferably 1 or more, more preferably 1.2 or more, and still more preferably 1.4 or more.

The thickness of the light-shielding insulating layer 30 is preferably 3 to 15 μm, more preferably 5 to 11 μm, because it tends to impair desired optical characteristics when it is too thin and tends to cause cracks when it is too thick.

As such a light-shielding insulating layer 30, various configurations can be obtained in which the surface resistance value, the glossiness, and the optical density of the surface are within the above ranges. Examples thereof include: as shown in fig. 1, a configuration of a single black resin layer formed of an insulating resin colored with a black coloring agent; as shown in fig. 2 or 3, the resin composition includes a black resin layer 30a formed of an insulating resin colored with a black colorant, and an insulating primer layer 30b or a matte paint layer (mat varnish)30c formed on one surface thereof.

Examples of the insulating resin constituting the black resin layer of the light-shielding insulating layer 30 include ethylene- α -olefin copolymers such as polyethylene, polypropylene, and ethylene-propylene copolymers, fluorine-based polymers such as polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, ethylene-vinyl acetate copolymers, polyvinyl alcohol, polyvinyl acetal, polyvinylidene fluoride, and polytetrafluoroethylene, polymethacrylate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyacrylonitrile, styrene-acrylonitrile copolymers, acrylonitrile-butadiene-styrene copolymer (ABS) resins, polyphenylene ether copolymer (PPE) resins, modified PPE resins, aliphatic polyamides, aromatic polyamides, polyimides, polyamide imides, polymethacrylic acid esters such as polymethyl methacrylate, polyacrylic acids, polycarbonate, polyphenylene sulfide, polysulfone, styrene based polyether nitrile, polyether ketone, polyketone, liquid crystal polymers, silicone resins, ionomers, thermoplastic resins, and thermoplastic elastomers such as styrene-butadiene block copolymers, vinyl chloride-isoprene block copolymers, hydrogenated vinyl chloride-isoprene block copolymers, thermoplastic elastomers, hydrogenated styrene-butadiene-based thermoplastic elastomers, hydrogenated butadiene-styrene-butadiene-styrene-based thermoplastic elastomers, hydrogenated butadiene-styrene-butadiene-styrene-butadiene-based thermoplastic elastomers, hydrogenated butadiene-styrene-butadiene-styrene-butadiene-styrene-butadiene-styrene-butadiene-styrene-butadiene-styrene.

In addition, as the black colorant, there can be mentioned: known black dyes and black pigments such as aniline black, carbon black, and titanium black. If the average particle size of these colorants is too small, the possibility of being difficult to mix uniformly with the insulating resin during production tends to be high, and if it is too large, the smoothness of the light-shielding insulating layer 30 tends to be reduced, and therefore the average particle size of the colorants is preferably 10 to 500nm, more preferably 50 to 100 nm. In addition, if the content of the black colorant in the black resin layer is too small, desired optical characteristics tend not to be obtained, and if too large, adhesion with an adjacent layer may be reduced or peeling may occur, and therefore the content of the black colorant is preferably 10 to 40% by mass, and more preferably 15 to 30% by mass.

In addition, as the insulating primer layer 30b shown in fig. 2, there are exemplified: an insulating undercoat layer obtained by mixing a filler such as silica with an insulating resin exemplified by a black resin layer to prevent blocking (blocking) as needed.

Since the thickness of the insulating primer layer 30b tends to be too small to obtain desired insulation properties, and too large to obtain desired shape retention properties, the thickness of the insulating primer layer 30b is preferably 2 to 10 μm, and more preferably 3 to 7 μm.

Further, as the matte paint layer 30c shown in fig. 3, there can be mentioned: the insulating resin exemplified as a black resin layer is preferably a matte paint layer obtained by forming a film containing 30 to 80 mass% of a filler having an average particle diameter of 0.1 to 10 μm, such as silica, barium sulfate, calcium carbonate, polyethylene beads, polystyrene beads, benzoguanamine beads, or the like, so as to achieve a preferable appearance having a matte texture and a good coating strength in a well-balanced manner.

Since the layer thickness of the matte varnish layer 30c tends to be too thin and to fail to obtain desired insulation properties, and too thick, the layer thickness of the matte varnish layer 30c is preferably 2 to 10 μm, and more preferably 3 to 7 μm.

When the light-shielding insulating layer 30 is a single-layer black resin layer as shown in fig. 1, aniline black is preferably used as the black colorant in view of the insulating property of the black colorant itself. In the case where the light-shielding insulating layer 30 has a two-layer structure as shown in fig. 2 or 3, nigrosine may be used as the black coloring agent of the black resin layer 30a, but since the insulating undercoat layer 30b or the matte varnish layer 30c, which secures insulation, carbon black, which itself exhibits conductivity, may be used within a range not impairing the effects of the present invention.

< conductive adhesion layer >

As the conductive adhesive layer 20 constituting the conductive sheet 100, a conventional conductive adhesive layer of a conductive sheet can be used. Examples thereof include: a conductive adhesive layer obtained by mixing conductive particles such as carbon black or metal particles with an insulating resin exemplified as a black resin layer in an amount sufficient to ensure conductivity with a surface resistance value of 500m Ω/□ or less and forming a film.

The thickness of the conductive adhesive layer 20 is preferably 10 to 35 μm, more preferably 15 to 25 μm, because the desired adhesiveness tends not to be obtained when the thickness of the conductive adhesive layer 20 is too small, and the desired conduction characteristics tend not to be obtained when the thickness is too large.

< production of conductive sheet >

The conductive sheet of the present invention can be produced by a known method. For example, a base substrate having metal layers laminated on both sides thereof is prepared by coating a resin film such as a PET film with a dry adhesive such as a urethane adhesive containing an isocyanate curing agent on one side thereof and laminating a metal layer such as an aluminum foil thereon, and then coating the other side with the dry adhesive and laminating the metal layer thereon. Next, a coating material for a conductive adhesive layer is applied to the release sheet, dried to form a conductive adhesive layer, and a base substrate is laminated thereon. Next, a black ink for forming a black resin layer is applied on the base substrate and dried, thereby forming a light-shielding insulating layer. Thereby, the conductive sheet of fig. 1 was obtained.

The conductive sheet of fig. 2 and 3 can be basically produced in the same manner as the conductive sheet of fig. 1, except that the black resin layer and the matte varnish layer or the insulating primer layer are applied and dried to form a film.

The conductive sheet of the present invention can be preferably applied to: an image display module in which the conductive portion is arranged on a plane having undulations, or an image display module in which the conductive portion is not arranged on the same plane.

As examples of the former, there can be exemplified: an image display module is configured by connecting a display panel of a notebook computer and the like with a substrate which is separately arranged by an arbitrary bending part and a step through a conductive sheet. The image display module exemplified in the notebook computer is also a part of the present invention.

In addition, as an example of the latter, there can be exemplified: an image display module is formed by combining a display surface control panel and an image display panel such as a liquid crystal display panel as a control object, wherein the display surface control panel is formed by arranging a surface electrode provided at a surface outer edge portion of the display surface control panel such as a touch panel and a back electrode provided at a back outer edge portion so as to wrap an outer edge portion of the display surface control panel and connecting the surface electrode and the back electrode through a conductive sheet. The image display module is also part of the invention.

Examples

Example 1

At 5μOne side of m-thick PET film (マイラー, Kimu デュポンフィルム (L.)) was 3g/m²Polyester resins (UE3220, ユニチカ, Inc.) using an isocyanate-based curing agent (コロネート L, POLYURETANE INDUSTRY, Japan) were applied (conversion of dry application amount), and 7 layers were further laminatedμSoft aluminum foil (1030N-0 material, manufactured by Japan) having a thickness of mFoil (strain)). The PET film is also laminated 7 on the other sideμA soft aluminum foil (1030N-0 material, Japan foil (Ltd.)) having a thickness of m was used as a base substrate.

A conductive black adhesive (an acrylic adhesive containing 10 mass% of carbon black) was applied to a release PET film so as to give a dry thickness of 25μm, and dried to form a conductive black adhesive layer, and the base substrate prepared before lamination is laminated on the conductive black adhesive layer.

Next, an insulating black ink { an ink (デクセリアルズ, manufactured by tokyo color materials industries, ltd.) obtained by dispersing nigrosine (tokyo color materials industries, ltd.) in a polyester resin (バイロン 200, tokyo kaki corporation) } was applied on the base substrate so as to reach 3 in terms of dry thicknessμm, and dried to form a light-shielding insulating layer. Thus, a conductive sheet having a structure shown in table 1 was obtained.

Example 2

Except for using 12μm-thick PET film (E5100, Toyo Boseki Co., Ltd.) in place of 5 of the base substrateμThe same operation as in example 1 was repeated except for the m-thick PET film, to obtain conductive sheets having the structures shown in table 1.

Example 3

Except using 3 from the base substrate sideμThe same operation as in example 1 was repeated except that a laminate of an m-thick insulating undercoat layer (polyester resin (バイロン 200, tokyo corporation))) and a carbon black ink layer { ink (デクセリアルズ (corporation)) } formed thereon, which was obtained by dispersing carbon black (MA8, mitsubishi chemical corporation) in polyester resin (バイロン 200, tokyo corporation)), was used as a light-shielding insulating layer, to obtain a conductive sheet having a structure shown in table 1.

Example 4

Except using 3 from the base substrate sideμAn m-thick carbon black ink layer { ink (デクセリアルズ (ltd)) obtained by dispersing carbon black (MA8, mitsubishi chemical corporation)) in a polyester resin (バイロン 200, eastern american spinning (ltd) } and 3μThe same operation as in example 1 was repeated except that the laminate of m-thick matte paint layers (LG6620, tokyo インキ (ltd)) was used as a light-shielding insulating layerConductive sheets having the compositions shown in table 1 were obtained.

Comparative example 1

Except for using 3μThe same operation as in example 1 was repeated except that an m-thick carbon black ink layer { ink (デクセリアルズ (ltd)) obtained by dispersing carbon black (MA8, mitsubishi chemical corporation)) in a polyester resin (バイロン 200, toyobo corporation) } was used as a light-shielding insulating layer, thereby obtaining a conductive sheet having a structure shown in table 1.

Comparative example 2

The urethane adhesive used in example 1 was applied to the metal layer of the base substrate before the formation of the carbon black ink layer, and 5 was laminatedμConductive sheets having the structures shown in table 1 were obtained by repeating the same operations as in comparative example 1 except that a PET film (マイラー, imperial デュポンフィルム, ltd.) having a thickness of m was used and a carbon black ink layer was formed thereafter.

Comparative example 3

Except for using 12μm-thick PET film (E5100, Toyo Boseki Co., Ltd.) instead of 5 sandwiched by aluminum foil of the base substrateμThe same operation as in comparative example 2 was repeated except for the m-thick PET film, to obtain conductive sheets having the composition shown in table 1.

Comparative example 4

Use is only at 5μThe same operation as in comparative example 1 was repeated except that a laminate in which a carbon black ink layer { ink (デクセリアルズ (ltd)) obtained by dispersing carbon black (MA8, mitsubishi chemical corporation)) in a polyester resin (バイロン 200, toyobo corporation) } was directly laminated on the surface of a base substrate, as a base substrate, one surface of a PET film having an m thickness, to which a soft aluminum foil used in example 1 was laminated via an adhesive was laminated, was used, and a conductive sheet having a structure shown in table 1 was obtained.

Comparative example 5

Except for using 12μm-thick PET film (E5100, Toyo Boseki Co., Ltd.) in place of 5 of the base substrateμThe same operation as in comparative example 4 was repeated except for the m-thick PET film, to obtain conductive sheets having the structures shown in table 1.

Comparative example 6

Except that 30 is laminated on the peeled PET filmμConductive adhesive films (Sui-80-M30, セーレン, Inc.) having a thickness of M were repeatedly used in comparative example 4 instead of forming a conductive adhesive layer, thereby obtaining conductive sheets having the structures shown in Table 1.

Comparative example 7

Except for using 12μm-thick PET film (E5100, Toyo Boseki Co., Ltd.) in place of 5 of the base substrateμThe same operation as in comparative example 6 was repeated except for the m-thick PET film, to obtain conductive sheets having the structures shown in table 1.

< evaluation >

The obtained conductive sheet was evaluated by tests for "curl characteristics", "shape retention", "shape following property (rebound resilience)", "insulation property (surface resistance value)", and "light blocking property (glossiness and optical density)" as described below. The results obtained are shown in Table 1.

"crimp characteristics"

The conductive adhesive layer-side release sheet of the test sample obtained by cutting the conductive sheet into short strips 15mm wide and 150mm long was peeled at a speed of 1000 mm/sec in the 180 ℃ direction, and the generated curl was visually confirmed. The generated curl was judged to be good when it was within 1 roll, and was judged to be bad when it exceeded 1 roll.

"shape Retention"

A conductive adhesive layer side release sheet of a test sample obtained by cutting the conductive sheet into short strips 15mm wide and 50mm long was peeled at a speed of 1000 mm/sec along the 180 ℃ direction, and the conductive adhesive layer side release sheet was bent 90 ℃ toward the light-shielding insulating layer side through the center of the sample, and it was visually confirmed whether the shape could be maintained for 10 seconds in this state. The shape can be held and the shape cannot be held, and the determination is good.

Shape following property (resilience) "

Taking down a stripping sheet on the conductive adhesive layer side of a test sample obtained by cutting a conductive sheet into a rectangle with the length of 15mm and the width of 10mm, sticking the stripping sheet on the long side to wrap the thickness part of an aluminum plate with the thickness of 1mm and cover the edge of the surface of the aluminum plate by 1mm, bending the rest part by 90 degrees, sticking the rest part on the back of the aluminum plate, and placing the aluminum plate in an environment with the temperature of 80 ℃ and the RH of 95 percent for 72 hours, wherein at the moment, whether stripping occurs or not is visually observed. The case where no peeling occurred was judged to be good, and the case where peeling occurred was judged to be bad.

Insulation (surface resistance) "

The surface resistance value of the surface of the light-shielding green insulating layer of the conductive sheet was measured by a resistance measuring instrument (ハイレスター, mitsubishi chemical アナリテック). Practically, the surface resistance value is required to be 1X 10⁸Omega/□ or more.

"light-shielding property (gloss and optical density)"

The gloss of the light-shielding insulating layer surface of the conductive sheet was measured by a gloss meter (グロスチェッカー IG-320, (manufactured by horiba ltd.) according to JIS Z8741 (angle of incidence 60). The gloss is practically required to be 80% or less. Further, the optical density of the surface of the light-shielding insulating layer was measured using an optical density meter (manufactured by reflection density meter RT924, Macbeth) according to JIS K7605. Practically, the optical density is required to be 1.4 or more. A conductive sheet satisfying these two properties was judged to be good.

In the case of the conductive adhesive layers of the conductive sheets of examples 1 to 4 and comparative examples 1 to 5 and the conductive nonwoven fabric reinforced adhesive films of comparative examples 6 and 7, samples cut into short strips of 100 × 25mm were attached to the ends of two copper foils (1 × 25 × 100mm) arranged in parallel at an interval of 50mm, and the resistance value between the two copper foils was measured using a resistance measuring instrument (milliohmmeter 4332B, Agillent). As a result, all samples showed very low resistance values of 50 to 60 m.OMEGA.which were much lower than 500 m.OMEGA..

The conductive sheets of examples 1 to 4 gave good results in all evaluation items.

In contrast, the conductive sheet of comparative example 1 had a low surface resistance value and could not exhibit insulation properties that could meet practical requirements, because the light-shielding insulating layer was formed using a carbon black ink that exhibited conductivity, instead of using an insulating black ink.

In addition, although the conductive sheet of comparative example 2 formed a light-shielding insulating layer using a carbon black ink instead of an insulating black ink, it exhibited good insulating properties because an insulating PET film was disposed under the carbon black ink layer, but had a problem in curl characteristics because the symmetry in the thickness direction of the base substrate was lost.

The conductive sheet of comparative example 3 was prepared by changing the resin film thickness of the base substrate of the conductive sheet of comparative example 2 from 5μm is thickened to 12μm, the symmetry in the thickness direction of the base material is inferior to that of comparative example 2, and as a result, a problem arises in shape-following properties.

The conductive sheets of comparative examples 4 and 5 each used a base substrate in which an aluminum foil was laminated only on one side, and therefore had good shape-following properties, but had problems in curl characteristics and shape-retaining properties.

In the conductive sheets of comparative examples 6 and 7, the non-woven fabric reinforced adhesive film was used as the conductive adhesive layer, and thus no problem was caused in curl characteristics, but problems were caused in shape retention and shape conformability because a base substrate in which only one side of an aluminum foil was laminated was used.

Industrial applicability

The conductive sheet of the present invention, in which a conductive adhesive layer is laminated on one surface of a base substrate and a light-shielding insulating layer is laminated on the other surface of the base substrate, uses a substrate having a structure in which metal layers of the same kind are formed on both surfaces of a resin film as the base substrate. Therefore, even when the conductive sheet is stretched, the metal layers on both sides of the resin film exhibit the same elongation, and therefore, the occurrence of curling can be greatly suppressed, and the conductive sheet can be bonded to a shape that changes such as a curved surface or a bent portion (corner portion) with good shape-following properties, and is excellent in shape-retaining properties. Therefore, the conductive sheet of the present invention can be used for manufacturing an image display module in which the conductive portions are arranged on a plane having undulations, or an image display module in which the conductive portions are arranged so as not to exist on the same plane.

Description of the symbols

1: a resin film;

2: a metal layer on the conductive adhesive layer side;

3: a metal layer on the light-shielding insulating layer side;

10: a base substrate;

20: a conductive adhesive layer;

30: a light-shielding insulating layer;

30 a: a black resin layer;

30 b: an insulating primer layer;

30 c: a matte paint layer;

100: a conductive sheet.

Claims (20)

1. The conductive sheet is formed by laminating a conductive adhesive layer on one surface of a base substrate and a light-shielding insulating layer on the other surface of the base substrate, wherein the base substrate has a structure in which metal layers having the same elongation are formed on both surfaces of a resin film, the thickness of the resin film constituting the base substrate, the thickness of the metal layer on the conductive adhesive layer side, and the thickness of the metal layer on the insulating layer side are all 5-20 [ mu ] m, and the metal layer is a metal foil.

2. The conductive sheet according to claim 1, wherein the metal layer has a tensile modulus of 45 to 200GPa according to JIS K7113.

3. The conductive sheet according to claim 1, wherein the light-shielding insulating layer surface of the conductive sheet has a thickness of 1.0X 10⁸A surface resistance value of not less than Ω/□, a glossiness of not more than 80%, and an optical density of not less than 1.

4. The conductive sheet according to claim 1, wherein the light-shielding insulating layer surface of the conductive sheet has a thickness of 1.0X 10¹⁰Surface resistance value of not less than omega/□, glossiness of not more than 40% and optical property of not less than 1.2And (4) concentration.

5. The conductive sheet according to claim 1, wherein the base substrate has a structure in which metal layers are laminated on both surfaces of the resin film via adhesive layers, respectively.

6. The conductive sheet according to claim 1, wherein the resin film constituting the base substrate has a linear expansion coefficient of 15 to 100 ppm/DEG C, and the metal layer has a linear expansion coefficient of 12 to 25 ppm/DEG C.

7. The conductive sheet according to claim 6, wherein a difference in linear expansion coefficient between the resin film and the metal layer constituting the base substrate is 40 ppm/DEG C or less.

8. The conductive sheet according to claim 1, wherein the resin film constituting the base substrate has a tensile modulus of 0.3 to 15GPa in accordance with JIS K7113.

9. The conductive sheet according to claim 8, wherein the difference in tensile modulus between the resin film constituting the base substrate and the metal layer of JISK7113 is 100GPa or less.

10. The conductive sheet according to claim 1, wherein the ratio of the thickness [ Mt1] of the metal layer on the conductive adhesive layer side to the thickness [ Bt ] of the resin film to the thickness [ Mt2] of the metal layer on the insulating layer side is [ Mt1 ]: [ Bt ]: [ Mt2] ═ 0.25 to 4: 1: 0.25 to 4.

11. The conductive sheet according to claim 1, wherein the light-shielding insulating layer is a black resin layer formed of an insulating resin colored with a black colorant.

12. The conductive sheet according to claim 11, wherein the black colorant is nigrosine.

13. The conductive sheet according to claim 1, wherein the light-shielding insulating layer comprises a black resin layer formed of an insulating resin colored with a black colorant, and an insulating undercoat layer or a matte paint layer formed on at least one surface thereof.

14. The conductive sheet according to claim 13, wherein the black colorant is carbon black.

15. The conductive sheet according to any one of claims 1 to 14, further comprising a structure in which a release PET film is laminated on the conductive adhesive layer side, and the conductive sheet exhibits the following shape-following properties:

< shape-following Property >

Taking down a stripping sheet on the conductive adhesive layer side of a test sample obtained by cutting a conductive sheet into a rectangle with the length of 15mm and the width of 10mm, sticking the stripping sheet on the long side to wrap the thickness part of an aluminum plate with the thickness of 1mm and cover the edge of the surface of the aluminum plate by 1mm, bending the rest part by 90 degrees and sticking the bent part on the back surface of the aluminum plate, and leaving the stripping-free stripping cover to be placed in an environment with the temperature of 80 ℃ and the RH of 95% for 72 hours.

16. The conductive sheet according to any one of claims 1 to 14, further comprising a structure in which a release PET film is laminated on the conductive adhesive layer side, and the conductive sheet exhibits the following curling properties:

< crimp Property >

When the conductive adhesive layer-side release sheet of the test sample obtained by cutting the conductive sheet into short strips 15mm wide and 150mm long was released at a speed of 1000 mm/sec along the 180 ℃ direction, no curl exceeding 1 roll was generated.

17. The conductive sheet according to any one of claims 1 to 14, further comprising a structure in which a release PET film is laminated on the conductive adhesive layer side, and the conductive sheet exhibits the following shape retention:

< shape Retention >

The conductive sheet was cut into a strip shape with a width of 15mm and a length of 50mm, and the conductive adhesive layer side release sheet of the test sample was peeled at a speed of 1000 mm/sec along the 180 ℃ direction, and was bent 90 ℃ toward the light-shielding insulating layer side through the center of the sample, and the shape could be maintained for 10 seconds in this state.

18. An image display module, wherein the conductive portions connected by the conductive sheet according to any one of claims 1 to 17 are arranged on a plane having undulations.

19. An image display module, wherein the conducting portions connected by the conductive sheet according to any one of claims 1 to 17 are arranged so as not to be present on the same plane.

20. An image display module comprising a display surface control panel and an image display panel controlled by the display surface control panel, which are connected by the conductive sheet according to any one of claims 1 to 17, wherein a front surface electrode provided at a front outer edge portion of the display surface control panel and a rear surface electrode provided at a rear outer edge portion are arranged on the conductive sheet so as to wrap an outer edge portion of the display surface control panel.