WO2015151674A1

WO2015151674A1 - Electroconductive shielding tape

Info

Publication number: WO2015151674A1
Application number: PCT/JP2015/055736
Authority: WO
Inventors: 修手嶋
Original assignee: デクセリアルズ株式会社
Priority date: 2014-03-31
Filing date: 2015-02-27
Publication date: 2015-10-08
Also published as: TW201606808A; JP2015196741A

Abstract

　Provided is an electroconductive shielding tape which does not become tacky, and in which a metal thin film does not shred. This electroconductive shielding tape (1) is configured so that an electroconductive adhesive layer (2) is disposed on one surface of a metal thin film (3), an electroconductive protective layer (4) is disposed on a surface on the reverse side of the metal thin film (3), and the electroconductive protective layer (4) has higher strength than the metal thin film (3), and the metal thin film (3) therefore does not break. The metal thin film (3) is electrically conductive in both a thickness direction and a spreading direction, the electroconductive adhesive layer (2) and the electroconductive protective layer (4) are electrically conductive in at least the thickness direction, and when electroconductive shielding tapes (1) are layered, the electroconductive shielding tapes (1) are electrically connected to each other.

Description

Conductive shield tape

The present invention relates to a conductive shield tape, and particularly to a conductive shield tape excellent in reworkability and conductivity.

Conventionally, as various display input means such as a PC monitor, a smart phone, a portable game machine, a digital audio player, a tablet terminal, a wearable terminal, or an in-vehicle monitor, a display device such as a liquid crystal display device or an organic EL panel, A touch panel is used that includes an input device that senses information on a screen position by applying pressure to the display device and outputs the information as an information signal.

In recent years, in such touch panel devices, fine pitch, light weight, and thinning have progressed, and the display device such as a liquid crystal panel and the touch panel are close to each other. May have an effect. Therefore, a conductive shield tape is attached to the display device as a ground line.

Japanese Unexamined Patent Publication No. 63-40216

By the way, in the display device such as a liquid crystal panel, the periphery of the image display unit has been narrowed in recent years, and with the progress of thinning, the conductive shield tape has been thinned and no curling or wrinkle occurs even in a narrow place. In addition to the workability that can be applied, there is also a need for reworkability if the application fails. Here, “rework” means that a tape once applied is peeled off and another tape is applied.
Further, since the conductive shield tape is superposed when being applied to the corner portion of the substrate of the display device, the conductivity in the thickness direction is also required in addition to the conductivity in the surface direction.

Here, a metal thin film is used as the conventional conductive shield tape (Patent Document 1). However, since the metal thin film is thin, if it is not an expert, it will be broken in the middle of the rework work, and the work efficiency will be improved. There is no reality.

Therefore, an object of the present invention is to provide a conductive shield tape excellent in sticking workability, reworkability, and conductivity.

In order to solve the above-described problems, the present inventor provides two aspects.
That is, in the first aspect of the conductive shield tape (1) according to the present invention, the conductive adhesive layer (2) is provided on one surface of the metal thin film (3), and the conductive protective layer (4) is the metal. A conductive shield tape (1) provided on the opposite surface of the thin film (3), wherein the conductive protective layer (4) contains a binder component (c1) and conductive particles (c2), The binder component (c1) has a number average molecular weight of 20000 or more and 30000 or less, a glass transition temperature of less than 5 ° C., and a hydroxyl group of the first polyester resin (a). The conductive shield tape (1) is characterized by reacting an isocyanate compound (c) of 15 equivalents or more with respect to the value.
The second aspect of the conductive shield tape (1) according to the present invention is that the conductive adhesive layer (2) is provided on one side of the metal thin film (3), and the conductive protective layer (4) is the metal. A conductive shield tape (1) provided on the opposite surface of the thin film (3), wherein the conductive protective layer (4) includes a binder component (c1) and conductive particles (c2), The binder component (c1) has a number average molecular weight of 20000 or more and 30000 or less, a first polyester resin (A) having a glass transition temperature of less than 5 ° C., and a number average molecular weight of 8000 or more and 20000 or less, 5 equivalents or more with respect to the average value of the hydroxyl values of the second polyester resin (b) having a glass transition temperature exceeding 35 ° C. and the first and second polyester resins (a) and (b). Conductive sheet characterized by reacting with an isocyanate compound (c) Is a Dotepu (1).
Moreover, this invention is a conductive shield tape (1) by which the peeling film (7) was stuck to the said conductive adhesive layer (2).
In the present invention, the conductive pressure-sensitive adhesive layer (2) and the conductive protective layer (4) are conductive shield tapes (1) having conductivity at least in the thickness direction.

In the conductive shield tape (1) of the present invention, the conductive adhesive layer (2), the metal thin film (3), and the conductive protective layer (4) are sequentially formed in both the first aspect and the second aspect. This is common in that an excess amount of the isocyanate compound (c) is reacted with the binder component (c1) constituting the conductive protective layer (4).
Such a conductive protective layer (4) is stronger than the metal thin film (3), and the metal thin film (3) serves as a support or reinforcement to prevent the metal thin film (3) from being shredded during rework. Fulfill.
In addition, if the surface of the conductive protective layer (4) is sticky, even if rework itself is possible, the work does not proceed smoothly and there is a high possibility that it will contaminate other areas. The layer (4) has an effect without stickiness.
In addition, when a plurality of sheets are laminated, the laminated conductive shield tapes (1) are electrically connected, so that they are suitable for adherends having various shapes.

Sectional drawing which shows the conductive shield tape of this invention

Hereinafter, embodiments of the present invention will be described according to items.
1. 1. Conductive shield tape 2. Conductive adhesive layer Metal thin film 4. 4. Conductive protective layer Manufacturing method of conductive shield tape

[1. Conductive shield tape]
The conductive shield tape (1) to which the present invention is applied is arranged between, for example, a frame portion of a liquid crystal panel and a device housing in which the liquid crystal panel is incorporated, thereby reducing noise charges generated in the liquid crystal panel. As shown in FIG. 1, the conductive adhesive layer (2), the metal thin film (3), and the conductive film are used on the release film (7) as shown in FIG. It has a protective layer (4).

One side of the metal thin film (3) is in contact with the conductive adhesive layer (2), the other side is in contact with the conductive protective layer (4), and the metal thin film (3) is in contact with the conductive adhesive. The layer (2) and the conductive protective layer (4) are electrically connected.
The metal thin film (3) has conductivity in both the thickness direction and the spreading direction (direction along the surface of the thin film), and the conductive protective layer (4) and the conductive adhesive layer (2) are electrically connected. Connected.

The conductive protective layer (4) and the conductive pressure-sensitive adhesive layer (2) have conductivity at least in the thickness direction. In addition to the thickness direction, it may have conductivity in the spreading direction.
Of the two conductive shield tapes (1), the other conductive shield tape (1) is provided on the surface of the conductive protective layer (4) of one conductive shield tape (1) due to the conductivity in the thickness direction. When the conductive adhesive layer (2) is brought into contact with and attached, the metal thin films (3) of the two conductive shield tapes (1) are electrically connected to each other.

[2. Conductive adhesive layer]
The conductive pressure-sensitive adhesive layer (2) is used for the purpose of attaching the conductive shield tape (1) to the surface of a device housing or the like. Specifically, a known pressure-sensitive adhesive (c3) containing conductive particles is used. Can be used. Examples of the adhesive (c3) include rubber adhesives, acrylic adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinyl pyrrolidone adhesives and polyadhesives. Examples include acrylamide-based adhesives and cellulose-based adhesives. Generally, rubber-based adhesives and acrylic-based adhesives are used.

Further, as the conductive particles (c4), known conductive particles (c4) generally used for conductive adhesives can be used. For example, metal powder such as nickel, silver and copper, metal coat metal powder such as silver coat copper powder, Ni coat of flat styrene particle core, metal coat resin powder such as Au flash plating, etc. can be used. . Moreover, you may mix and use said powder and particle | grains.

[3. Metal thin film]
The metal thin film (3) is a conductive layer for grounding noise charges of a liquid crystal panel or the like to which the conductive shield tape (1) is affixed. A thin metal film such as an aluminum foil or copper foil that is thin but excellent in conductivity is used. Preferably used.

When aluminum foil is used as the metal thin film (3), it has excellent corrosion resistance without any special anti-corrosion treatment, and the conductivity per unit weight is relatively high, so the weight of the conductive shield tape (1) is reduced. It can be made to be. Therefore, it is preferably used in terms of maintaining the conductive characteristics and reducing the weight of the electronic device provided with the conductive shield tape (1).

Moreover, when using a copper foil as the metal thin film (3), an electrolytic copper foil is suitably used because it has a matte surface and improves the adhesion to the conductive protective layer (4) by an anchor effect. Moreover, when using copper foil as a metal thin film (3), in order to prevent the electroconductivity fall by formation of an oxide film, it is preferable to perform processes, such as a rust prevention process and nickel plating.

The metal thin film (3) has a shape corresponding to the planar shape of the position where the conductive shield tape (1) is applied, and is formed in a film shape, for example.

The metal thin film (3) preferably has a thickness of 20 μm or less. With the downsizing and thinning of electronic devices, the conductive shield tape (1) is also required to be thin (for example, the total thickness is 70 μm or less). Therefore, the conductive shield tape (1) is also required to be thin in the thickness of each layer, and the metal thin film (3) is preferably 20 μm or less.

The metal thin film (3) preferably has a tensile strength of 100 MPa or less. As a result, the conductive shield tape (1) can be given a proper stiffness, and no curling will occur when it is peeled off from the release film (7). Etc. can be prevented.

[4. Conductive protective layer)
The conductive protective layer (4) supports or reinforces the metal thin film (3) during the reworking work to prevent it from being broken and to ensure conductivity in the thickness direction.

In the present invention, also in the first aspect or the second aspect, the conductive protective layer (4) is a conductive resin layer, and includes a binder component (c1) and conductive particles (c2). (c1) is an excess amount of isocyanate compound relative to the amount of hydroxyl group (hereinafter referred to as hydroxyl value) contained in the first polyester resin (a) having a predetermined number average molecular weight and the first polyester resin (a). It is a cured resin layer reacted with (c).
The conductive protective layer (4) is made of a material that is stronger and harder to break than the metal thin film (3) and can be bent. The conductive protective layer (4) is flexible. Can be granted.

(First aspect)
In the first aspect of the present invention, the first polyester resin (A) having a number average molecular weight of 20000 to 30000 and a glass transition temperature of less than 5 ° C. is used as the binder component (c1). . It is set to a temperature lower than the lowest temperature of the so-called normal temperature (5 to 35 ° C.).

Such a first polyester resin (a) usually has a hydroxyl value of 2 mgKOH / g to 10 mgKOH / g, and 15 equivalents or more of the isocyanate compound (c) is reacted with such a hydroxyl value.

When the amount is less than 15 equivalents, the strength of the entire conductive protective layer (4) is not sufficient, and as a result, the metal thin film (3) is shredded during rework, and the conductive protective layer (4) Since the surface is sticky, there is a problem that the rework work does not proceed smoothly. The isocyanate compound (C) may be 20 equivalents or less from a practical viewpoint.
In the first embodiment, the thickness of the conductive protective layer (4) is 2 μm to 30 μm, although it depends on the amount of the isocyanate compound (c).

As the isocyanate compound (C), isocyanate compounds such as hexamethylene diisocyanate, toluene diisocyanate, xylene diisocyanate, and hydrogenated xylene diisocyanate can be preferably used.

Further, as the conductive particles (c2), the conductive particles (c4) used in the above-mentioned conductive pressure-sensitive adhesive layer (2) can be used as they are. The size of the conductive particles is not particularly limited, but the diameter of the conductive particles is preferably 1 μm to 20 μm in consideration of the thickness of the conductive protective layer (4).

(Second aspect)
On the other hand, in the second embodiment of the present invention, specifically, as the binder component (c1), the first polyester having a number average molecular weight of 20000 to 30000 and a glass transition temperature of less than 5 ° C. Resin (a) and a second polyester resin (b) having a number average molecular weight of 8000 to 20000 and a glass transition temperature exceeding 35 ° C. are used in combination. In other words, the first polyester resin (A) whose glass transition temperature is lower than the lowest temperature at normal temperature (5 to 35 ° C) and the second polyester resin (B) whose glass transition temperature is higher than the highest temperature at normal temperature are used in combination. .

The hydroxyl value of the first polyester resin (a) is usually in the range of 2 mgKOH / g to 10 mgKOH / g, while the hydroxyl value of the second polyester resin (b) is usually 2 mgKOH / g to 10 mgKOH. / g. The first polyester resin (A) and the second polyester resin (B) preferably have a mass ratio of 90:10 to 50:50.

In the second embodiment of the present invention in which the first polyester resin (A) and the second polyester resin (B) are used in combination, 5 equivalents or more of the isocyanate compound (C) is reacted.
If the amount is less than 5 equivalents, as in the first embodiment, the metal thin film (3) may be broken or sticky on the surface during rework, and the rework work may not proceed smoothly. is there.

The thickness of the conductive protective layer (4) in the second embodiment is 2 μm to 30 μm, although it depends on the equivalent amount of the isocyanate compound (c) as in the first embodiment.

As the isocyanate compound (C), the same compound as the compound of the first embodiment can be used.

In addition, when further heat resistance is required for the conductive protective layer (4), the isocyanate compound (c) should be 5 equivalents or more, and the blending ratio of the first polyester resin (a) should be 80 or more. Alternatively, it can be handled by reacting 7 equivalents or more of the isocyanate compound (C).

[5. Manufacturing method of conductive shield tape]
Next, the manufacturing process of the conductive shield tape (1) will be described.
A binder component (c1), which is a raw material for the conductive protective layer (4), was dissolved in an organic solvent, and the conductive particles (c2) were contained in the release film, and the mixed coating solution was applied and dried to form a coating layer. Thereafter, a metal thin film (3) such as an aluminum foil is stuck on the coating layer, the coating layer is cured, a conductive protective layer (4) is formed, and the release film is removed to obtain an intermediate film A. The conductive particles (c2) are dispersed in the coating solution.

On the other hand, for example, an acrylic pressure-sensitive adhesive, which is a raw material for the conductive pressure-sensitive adhesive layer (2), is dissolved in an organic solvent to contain conductive particles, and a mixed coating solution is applied and dried. Thus, an intermediate film B on which the predetermined conductive pressure-sensitive adhesive layer (2) is formed is obtained.
Finally, the conductive shield tape (1) is obtained by laminating the surface of the metal film (3) of the intermediate film A with the surface of the conductive adhesive layer (2) of the intermediate film B facing each other. The conductive particles (c2) are dispersed in the coating solution.

The conductive shield tape (1) is cut into a predetermined length when used, and then the release film (7) of FIG. 1 is peeled off, and the conductive adhesive layer (2) is applied to a predetermined site. To do.

The conductive shield tape (1) not only has good electrical conductivity in the surface direction due to the metal thin film (3), but also has improved conductivity in the thickness direction with the metal thin film (3). Therefore, when the conductive shield tape (1) is used as, for example, a grounding wire for releasing noise charges generated in the liquid crystal panel to the equipment housing, the housing is surely provided even if the noise generation source is separated from the grounding point. In addition, it is possible to release electric charges, and it is possible to prevent adverse effects such as malfunction caused by noise.

The manufacturing process of the conductive shield tape (1) is different from the above procedure. First, the raw material liquid for the conductive adhesive layer (2) is applied to the release film (7) and dried to conduct the conductive process. After forming the adhesive layer (2), the metal thin film (3) is stuck on the surface of the conductive adhesive layer (2) to obtain the intermediate film C.
Next, the conductive shielding tape (1) may be obtained by applying and drying a coating solution as a raw material for the conductive protective layer (4) on the surface of the metal thin film (3) of the intermediate film C.

Next, an embodiment of the present invention will be described by dividing it into a first aspect and a second aspect.
(First aspect)
As raw materials for the conductive protective layer, 20 parts by mass of conductive particles (nickel particles, product number 255, manufactured by Vale Japan Co., Ltd.) and as the first polyester resin (I), Byron 500 (manufactured by Toyobo Co., Ltd., number average molecular weight) 23,000, glass transition temperature 4 ° C., hydroxyl value 5 mg KOH / 1 g) 100 parts by mass and isocyanate compound (C) (Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.) 7 parts by mass, 10 parts by mass, 13 parts by mass, or 25 Four types of coating solutions each containing parts by mass were formed as a metal thin film on an aluminum foil (1N30, manufactured by Nihon Foil Co., Ltd., thickness 7 μm, tensile strength 65 MPa) to a dry thickness of 15 μm. The intermediate film A was formed by carrying out a curing reaction at 40 ° C.
The four types of coating liquids differ in the equivalent amount of the isocyanate compound (C) with respect to the first polyester resin (A) having a different content of the isocyanate compound (C).

Next, as a raw material for the conductive pressure-sensitive adhesive layer, an acrylic copolymer 100 comprising conductive particles (nickel particles, product number 255, manufactured by Vale Japan KK), butyl acrylate, acrylic acid, and 2-hydroxyethyl methacrylate. A coating solution containing parts by mass and 0.5 parts by mass of an isocyanate compound (C) (Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) is applied on the release film (7) so that the dry thickness is 20 μm After forming a coating liquid layer, the film was dried to form an intermediate film B.

The target conductive shield tape (1) was obtained by laminating the conductive adhesive layer surface of the intermediate film B on the metal thin film surface of the intermediate film A. The tape obtained by changing the amount of the isocyanate compound (c) was evaluated by the following test method, and the results are shown in Table 1.

Test method 1. Reworkability After 1 hour has passed after slitting the obtained conductive shield tape (1) to the desired size (2cm x 10cm) and sticking it to SUS or glass plate as if the casing of the electronic equipment. The worker reworked. The case where reworking was possible was evaluated as ◯, and the case where the metal thin film was broken and cut during the reworking operation was evaluated as x.

2. In addition, when the above-mentioned rework work, the polyester resin was highly cross-linked and the surface of the conductive resin layer was not sticky, and the work was easy. . Normally, when the probe tack is 10 kgf / cm or more, the operator feels stickiness and the operation becomes difficult. Moreover, there exists a malfunction which will block when it makes it roll shape.

As described in Table 1, when 15 equivalents of the isocyanate compound (C) is contained in the first polyester resin (A), rework is possible and the surface is not sticky.

(Second aspect)
In addition to the first polyester resin (a), the blend amount of UE3200 (manufactured by Unitika, number average molecular weight 16000, glass transition temperature 65 ° C., hydroxyl value 6 mgKOH / g) as the second polyester resin (b), and isocyanate compound Except for changing the blending amount of (c), a conductive shield tape was prepared in the same manner as in the first example, and the same test as in the first embodiment was performed.
In the second embodiment, the heat resistance is further evaluated and is shown in Table 2.

As shown in Table 2, the evaluation items related to the rework work (surface stickiness, reworkability) are 5 equivalents or more of the isocyanate compound (c) with respect to the hydroxyl values of the first and second polyester resins (a) and (b). When it is contained, it can be evaluated as ○, and it can be seen that the rework work becomes smooth.
In addition, when heat resistance is required, the isocyanate compound (C) is made 5 equivalents or more and the blending ratio of the polyester resin (A) is 80 or more, or the isocyanate compound (C) is reacted for 7 equivalents or more. And good.

DESCRIPTION OF SYMBOLS 1 ... Conductive shield tape 2 ... Conductive adhesive layer 3 ... Metal thin film 4 ... Conductive protective layer 7 ... Release film c1 ... Binder component c2 ... Conductive particle

Claims

Conductive pressure-sensitive adhesive layer (2) is provided on one side of metal thin film (3), and conductive protective layer (4) is provided on the opposite side of metal thin film (3). Because
The conductive protective layer (4) contains conductive particles (c2) in the binder component (c1),
The binder component (c1) is
A first polyester resin (A) having a number average molecular weight of 20000 or more and 30000 or less and a glass transition temperature of less than 5 ° C .;
A conductive shielding tape (1) characterized in that a mixture of 15 equivalents or more of an isocyanate compound (C) with respect to the hydroxyl value of the first polyester resin (A) is a cured reaction.
Conductive pressure-sensitive adhesive layer (2) is provided on one side of metal thin film (3), and conductive protective layer (4) is provided on the opposite side of metal thin film (3). Because
The conductive protective layer (4) contains conductive particles (c2) in the binder component (c1),
The binder component (c1) is
A first polyester resin (A) having a number average molecular weight of 20000 or more and 30000 or less and a glass transition temperature of less than 5 ° C .;
A second polyester resin (b) having a number average molecular weight of 8000 or more and 20000 or less and a glass transition temperature exceeding 35 ° C .;
A mixture of 5 equivalents or more of the isocyanate compound (c) with respect to the average value of the hydroxyl value of the first and second polyester resins (a) and (b) is a resin obtained by curing reaction. Conductive shield tape (1).
The conductive shielding tape (1) according to any one of claims 1 and 2, wherein a release film (7) is attached to the conductive pressure-sensitive adhesive layer (2).
The conductive shield tape (1) according to any one of claims 1 and 2, wherein the conductive adhesive layer (2) and the conductive protective layer (4) are conductive at least in a thickness direction. ).
The conductive shield tape (1) according to claim 3, wherein the conductive pressure-sensitive adhesive layer (2) and the conductive protective layer (4) are conductive at least in the thickness direction.