Filament-shaped adhesive body

Abstract

The present invention relates to a filamentous adhesive body comprising a conductive core material having a plurality of filaments and an adhesive covering the surface of the core material in the longitudinal direction, the filamentous adhesive body having a resistance value in the Z-axis direction of 1.0 * 106 [omega / 100 mm] or less. The resistance value in the Z-axis direction of the wire-shaped adhesive body is measured after bonding two copper foil plates via the wire-shaped adhesive body and crimping the copper foil plates at a pressure of 0.35 MPa for 10 seconds for 30 minutes. Here, the Z-axis direction is a direction in which pressure is applied to the wire-shaped adhesive body when the two copper foil plates are crimped via the wire-shaped adhesive body. It needs to be described that the measurement is carried out at 23 DEG C.

Description

Technical Field

[0001] This invention relates to a filamentous adhesive formed by coating a core material along its length with an adhesive. Background Technology

[0002] In the manufacturing process of electrical and electronic equipment, when bonding multiple items, adhesives such as conductive adhesive sheets and conductive adhesive tapes that have adhesive and conductive properties to the objects being bonded are sometimes used.

[0003] Furthermore, the shape of the part of the items that are bonded together by an adhesive (hereinafter also referred to as the "bonding area") varies depending on the items being bonded.

[0004] For example, in electronic devices such as smartphones, due to miniaturization and design requirements, the bonding area of ​​the components used in these devices sometimes needs to be narrow. For instance, in fixing the glass cover of a smartphone, a narrow bonding area is specifically required for a borderless design.

[0005] Furthermore, depending on the shape of the object being bonded, sometimes it is required to make a complex shape, such as one that bends the bonding area.

[0006] Here, Patent Document 1 discloses a composite having good conductivity in the length direction of the composite and in the circumferential 360-degree (Y and Z axis directions) with the length direction as the axis (X axis). As one aspect, it discloses a composite formed by attaching the conductive linear component to the surface of the adhesive in a spiral shape.

[0007] Existing technical documents Patent documents Patent Document 1: International Publication No. 2022 / 209904 Summary of the Invention

[0008] The problem that the invention aims to solve The composite described in Patent Document 1 is considered to have good electrical conductivity in the longitudinal direction and in the circumferential 360-degree directions (Y and Z axes) about the longitudinal direction (X-axis). However, because the composite described in Patent Document 1 has conductive linear components on the surface of the adhesive, a portion of the surface of the adhesive is covered by conductive linear components, resulting in a large number of non-adhesive areas on the surface of the adhesive. As a result, it is difficult to say that it has sufficient adhesive strength.

[0009] In view of the above, one object of the present invention is to provide a filamentous adhesive that has excellent electrical conductivity and high adhesive strength when pressed onto an adhered object.

[0010] Methods for solving problems One aspect of the present invention is a filamentous adhesive comprising a conductive core material having multiple filaments, and an adhesive coating the longitudinal surface of the core material. The Z-axis resistance of the filamentous adhesive, measured under the following conditions, is 1.0 × 10⁻⁶. 6 [Ω / 100mm] or less.

[0011] (condition) Two copper foil plates were bonded together using the aforementioned filamentous adhesive. After pressing with a pressure of 0.35 MPa for 10 seconds, followed by 30 minutes, the resistance value of the filamentous adhesive in the Z-axis direction was measured. Here, the Z-axis direction refers to the direction in which pressure is applied to the filamentous adhesive when the two copper foil plates are pressed together. It should be noted that the measurement was performed at 23°C.

[0012] In one aspect of the present invention, the compression ratio of the filamentous adhesive at 23°C and compressed at 0.35 MPa for 10 seconds can be 13% or more.

[0013] In one aspect of the invention, the core material may comprise metal-coated fibers with a surface layer formed of resin and metal coating.

[0014] In one aspect of the present invention, the adhesive may contain a surfactant.

[0015] In one aspect of the present invention, the diameter of the filamentous adhesive can be less than 1 mm.

[0016] The effects of the invention One aspect of the present invention relates to a filamentous adhesive that exhibits excellent electrical conductivity and high adhesive strength when pressed onto an object. Attached Figure Description

[0017] [ Figure 1 ] Figure 1 This is a cross-sectional view of the filamentous adhesive according to an embodiment of the present invention in a direction perpendicular to the length direction.

[0018] [ Figure 2 ] Figure 2 This is a cross-sectional view showing the composite of the first adherend, the filamentous adhesive, and the second adherend. Here, Figure 2 (a) represents the state before the first and second adherends are pressed into the filamentous adhesive, and (b) represents the state after the first and second adherends are pressed into the filamentous adhesive.

[0019] [ Figure 3 ] Figure 3The figure illustrates a method for evaluating the resistance value of a filamentous adhesive in the Z-axis direction. (a) is a three-dimensional view, and (b) is a cross-sectional view along line AA in (a). Detailed Implementation

[0020] The embodiments of the present invention will be described in detail below, but the present invention is not limited to these embodiments.

[0021] It should be noted that in the following figures, sometimes the same symbols are used to describe components or parts that perform the same function, and sometimes repeated descriptions are omitted or simplified. Furthermore, in order to clearly illustrate the present invention, the embodiments described in the figures are schematic and do not necessarily accurately represent the dimensions or scale of the actual product.

[0022] In addition, in this specification, the use of expressions such as "~" is used to express numerical or physical property values ​​that include the values ​​before and after it.

[0023] One embodiment of the present invention relates to a filamentous adhesive comprising a conductive core material having multiple filaments and an adhesive coating the longitudinal surface of the core material. The Z-axis resistance of the filamentous adhesive, measured under the conditions described later, is 1.0 × 10⁻⁶. 6 [Ω / 100mm] or less.

[0024] It should be noted that, hereinafter, the conductive core material used in the filamentous adhesive involved in this embodiment will sometimes be referred to simply as "core material".

[0025] In this specification, the term "filamentous" refers to a shape that is sufficiently long in length direction relative to width direction, and in cross-sectional shape, the ratio of the length of the major axis to the length of the minor axis (major axis / minor axis) is, for example, 200 or more. In addition, it also refers to a shape like a filament that can be bent in multiple directions and at multiple angles.

[0026] Figure 1 This is a cross-sectional view of the filamentous adhesive 10 according to an embodiment of the present invention in a direction perpendicular to its length direction. The filamentous adhesive 10 according to this embodiment includes: a conductive core material 11 having multiple (in this example, 6) filaments 13; and an adhesive 12 covering the surface of the core material 11 in the length direction.

[0027] The adhesive force (difficulty of peeling the adhered objects from each other) when the filamentous adhesive 10 is used to bond the adhered objects together is significantly affected by the contact area between the filamentous adhesive 10 and the adhered objects.

[0028] When using the filamentous adhesive 10 of this embodiment, which includes a core material 11 having multiple filaments 13, to bond the adhered objects together, each filament 13 constituting the core material 11 can expand in a spreading manner, and the core material 11 can be deformed in a flattened manner. Therefore, compared with a filamentous adhesive having a core material composed of a single filament (monofilament), the filamentous adhesive 10 of this embodiment can contact the adhered objects with a larger area.

[0029] Furthermore, since the core material 11 of the filamentous adhesive 10 in this embodiment has multiple filaments 13, it has a large surface area, thus enabling the amount of adhesive 12 attached per unit length to increase.

[0030] For the reasons described above, the filamentous adhesive 10 of this embodiment can exhibit higher adhesive strength compared to a filamentous adhesive having a core material 11 of the same thickness (fineness) and composed of monofilaments.

[0031] To achieve the aforementioned effects, in the filamentous adhesive 10 of this embodiment, the core material 11 comprises multiple filaments 13. It should be noted that, hereinafter, the core material 11 comprising multiple filaments 13 is sometimes referred to as multifilament yarn. Furthermore, to further improve the adhesive strength of the filamentous adhesive 10, the number of filaments 13 constituting the core material 11 in this embodiment is preferably 2 or more, more preferably 3 or more, and even more preferably 4 or more. On the other hand, while maintaining a uniform thickness (fineness) of the core material 11, if the number of filaments 13 constituting the core material 11 increases, each filament 13 becomes thinner (fineness decreases). If each filament 13 becomes too thin, it may lead to a decrease in the strength and operability of the core material 11. Therefore, the number of filaments 13 constituting the core material 11 is preferably 2000 or less, more preferably 1500 or less, and particularly preferably 1000 or less.

[0032] Furthermore, in this embodiment, the core material 11 can be a twisted yarn or an untwisted yarn. That is, the twist count of the core material 11 can be greater than 0 twists / m or 0 twists / m. In addition, the core material 11 can be formed by combining multiple multifilaments that are twisted or untwisted yarns and twisting them together or by aggregating them without twisting them.

[0033] When a force is applied to the adhered objects bonded using the filamentous adhesive 10 of this embodiment in the direction in which they are torn apart, each filament 13 expands, and the core material 11 deforms in the coarse direction (the direction perpendicular to the length direction) in a manner that elongates in a direction parallel to the applied force. However, if the shape of the core material 11 is excessively deformed at this time, stress concentrates in the deformed portion, which easily becomes the starting point of peeling. Therefore, in order to achieve even better adhesive force, each filament 13 constituting the core material 11 preferably has a certain degree of aggregation. As described above, the core material 11 in this embodiment can be an untwisted filament or a twisted filament; that is, the twist count of the core material 11 in this embodiment can be 0 twists / m or more, but in order to have a certain degree of aggregation of each filament 13 constituting the core material 11, it is preferable to twist the core material 11. Specifically, the twist count of the core material 11 is preferably 10 twists / m or more, more preferably 20 twists / m or more, and even more preferably 30 twists / m or more.

[0034] On the other hand, when the adhered materials are bonded together by the filamentous adhesive 10, in order to allow the core material 11 to deform sufficiently and to increase the amount of adhesive 12 adhered per unit length, it is preferable that the twist of the core material 11 is not too strong. Therefore, the twist count of the core material 11 is preferably 3000 twists / m or less, more preferably 1500 twists / m or less, even more preferably 800 twists / m or less, and particularly preferably 250 twists / m or less.

[0035] Furthermore, when twisting the core material 11, based on the same viewpoint as above, it is preferable to control the twist coefficient, as expressed by the following formula (A). The twist coefficient is an index used to evaluate the effects of twisting (on the aggregation, deformability, and adhesion amount of the adhesive 12 of the core material 11, which are independent of the thickness of the core material 11). That is, the effect of the twist number on the core material 11 varies depending on the thickness of the core material 11, but as long as the twist coefficient is the same, the effect of twisting on the core material 11 is equal and independent of the thickness of the core material 11.

[0036] In this embodiment, the twist coefficient of the core material 11 is preferably 0 or more, and more preferably greater than 0. On the other hand, when the twist coefficient is 200 or less, the softness of the core material 11, and consequently the filamentous adhesive 10, is improved, making it easier to adhere to complex shapes and narrow portions such as curved portions, bends, and uneven portions. Therefore, the twist coefficient of the core material 11 is preferably 200 or less, more preferably 170 or less, more preferably 100 or less, more preferably 80 or less, and even more preferably less than 50.

[0037] [Mathematical Expression 1] It should be noted that in formula (A), K is the twist coefficient, T is the number of twists (unit: [twist / m]), and D is the fineness (unit: [dtex]).

[0038] Furthermore, the filamentous adhesive 10 of this embodiment has a conductive core material 11 as the core material 11. By using the conductive core material 11, the resistance value of the filamentous adhesive 10 having the core material 11 in the Z-axis direction is easily reduced.

[0039] As the conductive core material 11, examples include conductive wires and articles made of bundled metal wires. From the viewpoint of flexibility, conductive wires are preferred.

[0040] As a conductive filament, it is preferable to have a filament containing conductive fibers as filament 13. Examples include fiber bundles containing conductive fibers or fibers containing conductive fibers, or twisted filaments, braided filaments, spun filaments, blended filaments, etc., using conductive fibers or fibers containing conductive fibers.

[0041] The conductive fiber can be any fiber that is conductive. For example, it can be a fiber incorporating carbon fibers, carbon particles, metal fibers, or metal particles, or it can be a fiber containing conductive materials such as metals, conductive oxides, carbon-based conductive materials (graphite, carbon, carbon nanotubes, graphene, etc.), or conductive polymers, or a fiber coated with such conductive materials. Among these, considering high flexibility, fibers coated with conductive materials are preferred, and metal-coated fibers, which are fibers formed from resin (polymer materials) with a metal coating on their surface, are particularly preferred.

[0042] Here, the fiber coated with a conductive material can be either a natural fiber or a chemical fiber.

[0043] Examples of natural fibers include plant fibers and animal fibers.

[0044] In addition, examples of chemical fibers include: rayon, cuprammonium cellulose, acetate, Promix, nylon, aramid, vinylon, vinylidene fiber, polyvinyl chloride, acrylic fiber, polyolefins (polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, etc.), polyester resins (polyethylene terephthalate, etc.), vinyl chloride resin, vinyl acetate resin, polyimide resin, polyamide resin, fluoropolymers, polyurethane, Polyclar fiber, polylactic acid, and other resins (polymer materials); synthetic rubbers (natural rubber, polyurethane, etc.); and fibers formed from foams such as foamed polyurethane and foamed polychloroprene rubber. From the viewpoint of availability, chemical fibers formed from resins are preferred, and chemical fibers formed from polyester, nylon, acrylic fibers, etc., are particularly preferred.

[0045] Furthermore, the metal used as the aforementioned conductive material is not particularly limited. For example, examples include elemental metals containing silver, copper, aluminum, nickel, etc., or compounds or alloys containing one or more of these elements. Among these, from the perspective of high conductivity, elemental metals containing silver, copper, etc., or compounds or alloys containing one or more of these elements are preferred.

[0046] Metal-coated fibers, which are fibers formed from resin, have metal coatings on their surface. Examples of metal-coated fibers include copper sulfide coated nylon fibers, copper sulfide coated acrylic fibers, silver coated polyester fibers, and silver coated nylon fibers.

[0047] From the viewpoint of fiber strength, the fiber diameter (monofilament diameter) of the conductive fiber is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more. Furthermore, from the viewpoint of softness and appearance, it is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less. The fiber diameter (monofilament diameter) of the conductive fiber is, for example, 5 to 200 μm.

[0048] The total fineness and single fiber fineness of the conductive fibers can be appropriately selected according to the application of the filamentous adhesive 10, preferably with a total fineness in the range of 20 to 2000 dtex and a single fiber fineness in the range of 0.5 to 10.0 dtex.

[0049] In addition, the metal wires (filaments 13) in the core material 11 obtained by bundling metal wires can be, for example, nickel-chromium wire, copper wire, silver wire, etc.

[0050] The diameter of the metal wire is not particularly limited, but from the viewpoint of flexibility and conductivity, it is preferably 10 to 200 μm, and more preferably 20 to 100 μm.

[0051] Furthermore, in this embodiment, the resistance value of the conductive core material 11 along its length (X-axis direction) is preferably 1.0 × 10⁻⁶. 6 [Ω / 100mm] or less, more preferably 1.0×10 5 [Ω / 100mm] or less, more preferably 1.0 × 10 4 [Ω / 100mm] or less. The resistance of the core material 11 in the X-axis direction is 1.0 × 10⁻⁶. 6 When the resistance is below [Ω / 100mm], the resistance value of the filamentous adhesive 10 having the core material 11 in the Z-axis direction is easily reduced.

[0052] It should be noted that the lower limit of the resistance value of the conductive core material 11 in the X-axis direction is not specifically limited, but is 1.0 × 10⁻⁶. -1[Ω / 100mm] The above is the actual value. The resistance value of the conductive core material 11 in the X-axis direction is, for example, 1.0 × 10⁻⁶. -1 [Ω / 100mm]~1.0×10 6 [Ω / 100mm].

[0053] Here, the resistance value of the conductive core material 11 along its length (X-axis direction) is measured, for example, using the measurement method described in the Example 1 column.

[0054] Furthermore, the filaments 13 forming the core material 11 in the filamentous adhesive 10 can be hollow filaments. Generally, hollow filaments are flexible and easily deformable in the thickness direction, so the core material 11 obtained using hollow filaments is also flexible and easily deformable in the thickness direction.

[0055] Therefore, when hollow filaments are used in the filaments 13 forming the core material 11, the aforementioned flattening deformation of the core material 11 is more likely to occur. Furthermore, if the core material 11 is highly flexible, when force is applied in the direction in which the adhered objects bonded by the filamentous adhesive 10 are torn apart, stress dispersion due to deformation of the core material 11 is more likely to occur. Therefore, stress is less likely to be applied at the interface (adhesive surface) between the filamentous adhesive 10 and the adhered objects, and peeling is less likely to occur. Considering these aspects, if hollow filaments are used for the filaments 13 forming the core material 11, a filamentous adhesive 10 with particularly excellent adhesive strength can be obtained.

[0056] It should be noted that hollow yarn is usually brittle, so when hollow yarn is used in the filament 13 that forms the core material 11, it is preferable to use it without twisting.

[0057] The fineness (fineness) of the core material 11 in the filamentous adhesive 10 is not particularly limited. It can be adjusted appropriately according to the application of the filamentous adhesive 10 and the type of material to be bonded. For example, the fineness is about 20~2000 dtex.

[0058] It should be noted that, as needed, the core material 11 can be combined with various additives such as fillers (inorganic fillers, organic fillers, etc.), anti-aging agents, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, plasticizers, and colorants (pigments, dyes, etc.). For the surface of the core material 11, known or conventional surface treatments such as corona discharge treatment, plasma treatment, and primer coating can be applied.

[0059] In the filamentous adhesive 10 of this embodiment, the adhesive 12 is not particularly limited, and known adhesives can be used. Examples include acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluorinated adhesives, and epoxy adhesives. From the perspective of adhesion, rubber adhesives and acrylic adhesives are preferred, and acrylic adhesives are particularly preferred. It should be noted that only one type of adhesive can be used, or two or more can be used in combination.

[0060] Acrylic adhesives are adhesives based on polymers of the following monomers. These monomers are mainly composed of alkyl methacrylates such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, and isononyl acrylate, with the addition of modifying monomers such as acrylonitrile, vinyl acetate, styrene, methyl methacrylate, acrylic acid, maleic anhydride, vinylpyrrolidone, glycidyl methacrylate, dimethylaminoethyl methacrylate, hydroxyethyl acrylate, and acrylamide as needed.

[0061] Rubber-based adhesives are adhesives that use natural rubber, styrene-isoprene-styrene block copolymers, styrene-butadiene-styrene block copolymers, styrene-ethylene-butene-styrene block copolymers, styrene-butadiene rubber, polybutadiene, polyisoprene, polyisobutylene, butyl rubber, chloroprene rubber, silicone rubber, and other rubber-based polymers as the main agents.

[0062] In addition, these adhesives can be appropriately combined with tackifying resins such as rosin-based, terpene-based, styrene-based, aliphatic petroleum-based, aromatic petroleum-based, xylene-based, phenol-based, coumarone-indene-based, and their hydrides, as well as crosslinking agents, viscosity modifiers (thickeners, etc.), leveling agents, peel modifiers, plasticizers, softeners, fillers, colorants (pigments, dyes, etc.), surfactants, antistatic agents, preservatives, anti-aging agents, ultraviolet absorbers, antioxidants, light stabilizers, and various other additives.

[0063] It should be noted that any type of adhesive, either solvent-based or water-dispersible, can be used as the adhesive 12. Here, considering the ability to apply at high speed, environmental friendliness, and minimal impact of the solvent on the core material 11 (swelling, dissolution), a water-dispersible adhesive is preferred, and a water-dispersible acrylic adhesive is more preferred. It should be noted that, for example, an emulsion-type adhesive manufactured by emulsion polymerization can be cited as an example of a water-dispersible adhesive. Furthermore, since surfactants (emulsifiers) are used during emulsion polymerization, emulsion-type adhesives typically contain surfactants (emulsifiers).

[0064] In addition, the resistance value of the filamentous adhesive 10 in the Z-axis direction will be explained below.

[0065] Figure 2 A cross-sectional view is shown of the composite of the first adherend 21, the filamentous adhesive 10, and the second adherend 22. Here, Figure 2 (a) indicates the state before the first adherend 21 and the second adherend 22 are pressed together with the filamentous adhesive 10, that is, the state before the first adherend 21 and the second adherend 22 are bonded together by the filamentous adhesive 10. Additionally, Figure 2 (b) indicates the state after the first adherend 21 and the second adherend 22 are pressed together by the filamentous adhesive 10, that is, the state after the first adherend 21 and the second adherend 22 are bonded together by the filamentous adhesive 10.

[0066] in addition, Figure 2 In this embodiment, the length direction of the filamentous adhesive 10 (core material 11) is set as the X-axis direction, and a cross-sectional view of the composite is shown in a direction perpendicular to this X-axis direction. Furthermore, in this embodiment, when the first adherend 21 and the second adherend 22 are pressed onto the filamentous adhesive 10, the direction in which pressure is applied to the filamentous adhesive 10 is set as the Z-axis direction. Additionally, Figure 2 In the above view, the direction perpendicular to the Z-axis will be taken as the Y-axis direction.

[0067] In this embodiment, the resistance value of the filamentous adhesive 10 in the Z-axis direction, measured under the following conditions, is 1.0 × 10⁻⁶. 6 [Ω / 100mm] or less. Here, under the following conditions, two copper foil plates are used as the first adhesive 21 and the second adhesive 22. However, using two copper foil plates as adhesives under the following conditions is only to specify the resistance value in the Z-axis direction of the filamentous adhesive 10, and there are no limitations on the material, shape, etc. of the adhesives that can be used to bond the filamentous adhesive 10.

[0068] (condition) Two copper foil plates were bonded together using the aforementioned filamentous adhesive 10. After pressing with a pressure of 0.35 MPa for 10 seconds and then for 30 minutes, the resistance value of the filamentous adhesive 10 in the Z-axis direction was measured. Here, the Z-axis direction refers to the direction in which pressure is applied to the filamentous adhesive 10 when the two copper foil plates are pressed together. It should be noted that the measurement was performed at 23°C.

[0069] In this embodiment, more specifically, the resistance value of the filamentous adhesive 10 in the Z-axis direction measured under the above conditions can be determined using the following measurement method.

[0070] First, prepare two copper foil plates with dimensions of 30mm × 60mm × 0.5mm thickness.

[0071] A 100mm long filament adhesive 10 is attached to one of the copper foil sheets in a square shape with a side length of 25mm. Then, another copper foil sheet is attached and pressed together with a pressure of 0.35MPa for 10 seconds.

[0072] Thirty minutes after crimping, clamp terminals were connected to the ends of the bonded copper foil plates, a voltage of 0.4V was applied, the current flowing through was measured, and the resistance value of the filamentous adhesive 10 in the thickness direction (Z-axis direction), which is approximately orthogonal to the length direction, was calculated. It should be noted that the measurement was performed at room temperature (23°C).

[0073] It should be noted that, regarding the above-mentioned measurement methods, please refer to... Figure 3 The specific details are further explained in the Example section.

[0074] In this embodiment, the resistance value of the filamentous adhesive 10 in the Z-axis direction, measured under the above conditions, is 1.0 × 10⁻⁶. 6 [Ω / 100mm] or less, preferably 1.0 × 10 5 [Ω / 100mm] or less, more preferably 1.0×10 4 [Ω / 100mm] or less. Under the above conditions, the Z-axis resistivity of the filamentous adhesive 10 was 1.0 × 10⁻⁶. 6 When the conductivity is below [Ω / 100mm], the filamentous adhesive 10 itself has high conductivity.

[0075] It should be noted that the lower limit of the resistance value of the filamentous adhesive 10 in the Z-axis direction measured under the above conditions is not specifically limited, and is 1.0 × 10⁻⁶. -1 [Ω / 100mm] The above is the actual value. Under the above conditions, the resistance value of the filamentous adhesive 10 in the Z-axis direction is, for example, 1.0 × 10⁻⁶. -1 [Ω / 100mm]~1.0×10 6 [Ω / 100mm].

[0076] The resistance value of the filamentous adhesive 10 in the Z-axis direction, measured under the above conditions, can be adjusted by the structure and material of the conductive core material 11, the paste ratio (described later), etc. For example, the structure and material of the core material 11 affect the resistance value of the core material 11; for example, the type of metal in the metal-coated fiber can significantly affect the resistance value of the core material 11.

[0077] In the filamentous adhesive 10 of this embodiment, the mass ratio (paste ratio) of the adhesive 12 relative to the total mass of the filamentous adhesive 10 is preferably 10 to 90 by mass.

[0078] When the paste ratio is 10% by mass or more, the filamentous adhesive 10 readily possesses sufficient adhesive strength. A paste ratio more preferably is 20% by mass or more, and even more preferably is 25% by mass or more.

[0079] Furthermore, when the paste ratio is 90% by mass or less, the resistance of the filamentous adhesive 10 tends to decrease. A paste ratio of 80% by mass or less is more preferred, and 75% by mass or less is even more preferred.

[0080] The paste ratio (mass %) in the filamentous adhesive 10 can be calculated, for example, by subtracting the mass (weight) of the core material 11 from the mass (weight) of the filamentous adhesive 10, taking the resulting value as the mass (weight) of the adhesive, dividing the mass (weight) of the adhesive by the mass (weight) of the filamentous adhesive 10, and multiplying the resulting value by 100.

[0081] Furthermore, regarding the filamentous adhesive 10 of this embodiment, the compression ratio when compressed at 0.35 MPa for 10 seconds at 23°C is preferably 13% or more, more preferably 14% or more, and even more preferably 15% or more.

[0082] It should be noted that the method for determining the compression ratio is described in detail in the Example 1 section.

[0083] like Figure 2 As shown in (b), when the first adherend 21 and the second adherend 22 are pressed (bonded) by the filamentous adhesive 10, the filamentous adhesive 10 deforms due to pressure, and therefore differs from the shape before pressing (refer to...). Figure 2 Compared to (a), the conductive core material 11 (filament 13) included in the filamentous adhesive 10 is more likely to be closer to the first adherend 21 and the second adherend 22, resulting in a lower resistance value in the Z-axis direction of the filamentous adhesive 10. The above-mentioned compression ratio is an indicator of the ease with which the filamentous adhesive 10 deforms under pressure. There is a tendency for a higher compression ratio to result in a lower resistance value in the Z-axis direction of the filamentous adhesive 10, which is therefore preferred.

[0084] Furthermore, when using the filamentous adhesive 10 to bond the adhered objects together, a higher compression ratio makes the filamentous adhesive 10 more easily deformable, resulting in a larger contact area with the adhered objects and improved adhesion. In addition, a higher compression ratio makes it easier for stress dispersion due to the deformation of the core material 11 to occur when force is applied in the direction in which the adhered objects bonded using the filamentous adhesive 10 are torn apart. Therefore, it is less likely to apply stress to the interface (adhesive surface) between the filamentous adhesive 10 and the adhered objects, thus reducing the likelihood of peeling.

[0085] To further improve the adhesive strength of the filamentous adhesive 10 of this embodiment, it is preferable to attach a large amount of adhesive 12 to the core material 11. Specifically, the amount of adhesive 12 attached to the filamentous adhesive 10 of this embodiment (weight of adhesive 12 per unit length) is preferably 5 mg / m or more, more preferably 8 mg / m or more, and even more preferably 16 mg / m or more. On the other hand, if the amount of adhesive 12 attached is excessive, the core material 11 needs to be coated with adhesive 12 multiple times during the manufacturing process, or the drying time of the applied adhesive 12 is time-consuming, resulting in low manufacturing efficiency. Therefore, the amount of adhesive 12 attached to the filamentous adhesive 10 of this embodiment is preferably 200 mg / m or less, more preferably 180 mg / m or less, and even more preferably 160 mg / m or less.

[0086] The adhesive 12 can cover all or part of the surface of the core material 11 along its length, preferably covering the entire circumference of the surface of the core material 11 along its length. The entire circumference of the surface of the core material 11 refers to the entire circumference of the core material 11, that is, a full 360° circumference around the centerline of the core material 11 along its length.

[0087] However, the end face of the core material 11 may or may not be covered by the adhesive 12. For example, in cases where the filamentous adhesive 10 is cut during manufacturing or use, the end face of the core material 11 may sometimes not be covered by the adhesive 12.

[0088] By covering the entire circumference of the longitudinal surface of the core material 11 with adhesive 12, a filamentous adhesive body 10 with excellent strength can be obtained. This is presumably because the core material 11 is not exposed on the surface of the filamentous adhesive body 10, thus preventing stress concentration on a portion of the core material 11 and subsequent breakage.

[0089] Furthermore, by covering the entire circumference of the surface of the core material 11 along its length direction with adhesive 12, gaps are less likely to occur at the bonding portion between the filamentous adhesive 10 and the adhered object, thus enabling the production of a filamentous adhesive 10 with superior adhesion.

[0090] Furthermore, in the filamentous adhesive 10 of this embodiment, the core material 11 may have multiple filaments 13, and the adhesive 12 may cover the longitudinal surface of the core material 11 and be impregnated in the core material 11. Here, "the adhesive 12 is impregnated in the core material 11" means that the adhesive 12 is present among the multiple filaments 13 within the core material 11. If the adhesive 12 is impregnated in the core material 11, the adhesion between the adhesive 12 and the core material 11 is maintained, they are not easily peeled off, and the strength of the filamentous adhesive 10 is improved.

[0091] Furthermore, in the filamentous adhesive 10 of this embodiment, there may be a gap between the core material 11 and the adhesive 12.

[0092] From the viewpoint of strength and operability, the diameter of the filamentous adhesive 10 according to this embodiment is preferably 0.1 mm or more, and more preferably 0.2 mm or more. Furthermore, from the viewpoint of self-adhesion, the diameter of the filamentous adhesive 10 is preferably 1 mm or less, and more preferably 0.9 mm or less. It should be noted that even if the diameter of the filamentous adhesive 10 in this embodiment is as small as, for example, 0.3 mm or less, it can still have sufficient adhesive strength.

[0093] The following describes an example of a method for manufacturing the filamentous adhesive 10 according to this embodiment. It should be noted that the method for manufacturing the filamentous adhesive 10 according to this embodiment is not limited to the method described below.

[0094] The filamentous adhesive 10 of this embodiment can be obtained by coating the surface of the core material 11 with an adhesive coating liquid through methods such as liquid immersion, impregnation, or coating, followed by heating and drying. The coating liquid can be applied using conventional coating machines such as gravure roller coaters, reverse roller coaters, kiss roller coaters, dip roller coaters, bar coaters, doctor blade coaters, and spray coaters. The drying temperature and time are not particularly limited and can be set appropriately. The drying temperature is preferably 40°C to 200°C, more preferably 50°C to 180°C, and particularly preferably 70°C to 120°C. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

[0095] The filamentary adhesive 10 of this embodiment has good electrical conductivity and can be adhered to narrow components and narrow areas. It is also easily applied to complex shapes such as curves, curved surfaces, and uneven surfaces. In addition, considering its excellent adhesive strength, it can be used for bonding various items.

[0096] For example, the filamentous adhesive 10 of this embodiment can be suitable for fixing articles in the manufacture of electronic devices, and can be applied to fixing conductive wire components, etc.

[0097] Specifically, the filamentous adhesive 10 of this embodiment can be suitably used, for example, to fix conductive linear components such as wires, conductive fibers, conductors, and narrow articles in a desired shape. Even when fixing wires or narrow linear components to other articles in complex shapes, the filamentous adhesive 10 of this embodiment can accommodate the complex shapes of the wires or narrow articles, and can firmly fix them with excellent operability while suppressing spillage, wrinkles, and overlap.

[0098] As explained above, the following matters are recorded in this instruction manual.

[0099] (1) A filamentous adhesive comprising a conductive core having multiple filaments and an adhesive covering the longitudinal surface of the core. The Z-axis resistivity of the aforementioned filamentous adhesive, measured under the following conditions, is 1.0 × 10⁻⁶. 6 [Ω / 100mm] or less.

[0100] (condition) Two copper foil plates were bonded together using the aforementioned filamentous adhesive. After pressing with a pressure of 0.35 MPa for 10 seconds, followed by 30 minutes, the resistance value of the filamentous adhesive in the Z-axis direction was measured. Here, the Z-axis direction refers to the direction in which pressure is applied to the filamentous adhesive when the two copper foil plates are pressed together. It should be noted that the measurement was performed at 23°C.

[0101] (2) The filamentous adhesive as described in (1) has a compression rate of more than 13% when compressed at 0.35 MPa for 10 seconds at 23°C.

[0102] (3) The filamentous adhesive as described in (1) or (2), wherein the core material comprises a metal-coated fiber with a surface layer of resin-formed fibers coated with metal.

[0103] (4) The filamentous adhesive as described in any one of (1) to (3), wherein the aforementioned adhesive comprises a surfactant.

[0104] (5) The filamentous adhesive as described in any one of (1) to (4), wherein the diameter of the aforementioned filamentous adhesive is 1 mm or less.

[0105] Example The present invention will be specifically described below through examples, but the present invention is not limited to these examples in any way.

[0106] <Example 1> (Preparation of emulsion-based acrylic polymer 1) Add 40 parts by mass of deionized water to a reaction vessel equipped with a condenser, nitrogen inlet tube, thermometer, and stirrer. While introducing nitrogen gas, stir at 60°C for at least 1 hour to perform nitrogen replacement. Add 0.1 parts by mass of 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropanediamine]n hydrate (polymerization initiator) to the reaction vessel. While maintaining the system at 60°C, gradually add monomer emulsion A as described below dropwise over 4 hours to carry out emulsion polymerization.

[0107] Here, as monomeric emulsion A, the substance obtained by emulsifying 85 parts by weight of 2-ethylhexyl acrylate, 13 parts by weight of methacrylic acid, 1.25 parts by weight of acrylic acid, 0.75 parts by weight of methacrylic acid, 0.05 parts by weight of lauryl mercaptan (chain transfer agent), 0.02 parts by weight of γ-methacryloyloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd., trade name "KBM-503") and 2 parts by weight of polyoxyethylene lauryl sulfate (emulsifier) ​​with 30 parts by weight of deionized water is used.

[0108] After the addition of monomer emulsion A was completed, the system was kept at 60°C for 3 hours. After cooling the system to room temperature, the pH was adjusted to 7 by adding 10% ammonia to obtain emulsion-based acrylic polymer 1 (water-dispersible acrylic polymer 1).

[0109] (Preparation of adhesive coating liquid 1) Relative to 100 parts by weight of the acrylic polymer contained in the emulsion-based acrylic polymer 1, 35 parts by weight of a tackifying resin emulsion (manufactured by Arakawa Chemical Industry Co., Ltd., trade name "TAMANOLEE200NT") and 0.475 parts by weight of a thickener (Toa Synthetic Co., Ltd., trade name "AronB-500") based on solid content were added. Then, deionized water was added to adjust the solid content concentration to 45% by weight, resulting in adhesive coating liquid 1.

[0110] (Manufacturing of filamentous adhesives) As the core material, a multifilament yarn is prepared by twisting copper sulfide coated nylon fibers (trade name "THUNDERON" (registered trademark) of Nippon Kamo Dyeing Co., Ltd.) with a fineness of 235 dtex and a filament number of 15 strands, with 200 twists per meter.

[0111] The adhesive coating liquid 1 was applied to the core material by immersion using a coating roller. Then, it was dried at 100°C for 1 minute to obtain a filamentous adhesive with a paste ratio of 18% by mass.

[0112] <Example 2> Adhesive coating liquid 1 was coated by using a coating roller immersion process to obtain a filamentous adhesive with a paste ratio of 34% by mass. Otherwise, the same procedure as in Example 1 was followed to obtain the filamentous adhesive of Example 2.

[0113] <Example 3> By applying adhesive coating liquid 1 through a liquid immersion process using a coating roller, a filamentous adhesive with a paste ratio of 48% by mass was obtained. Otherwise, the same procedure as in Example 1 was followed to obtain the filamentous adhesive of Example 3.

[0114] <Example 4> As the core material, a multifilament yarn was prepared by twisting silver-coated polyester fiber (SEIREN Corporation trade name "Metaflex") with a fineness of 165 dtex and a filament number of 60 strands at a rate of 0 twists per 1m (twist coefficient 0). Adhesive coating liquid 1 was applied with a paste ratio of 69% by mass. Otherwise, the same procedure as in Example 1 was followed to obtain the filamentous adhesive of Example 4.

[0115] <Example 5> As the core material, a multifilament yarn was prepared by twisting silver-coated polyester fiber (SEIREN Corporation trade name "Metaflex") with a fineness of 165 dtex and a filament number of 60 strands at a rate of 80 twists per 1m (twist coefficient 10). Adhesive coating liquid 1 was applied with a paste ratio of 68% by mass. Otherwise, the same procedure as in Example 1 was followed to obtain the filamentous adhesive of Example 5.

[0116] <Example 6> As the core material, a multifilament yarn was prepared by twisting silver-coated polyester fiber (SEIREN Corporation trade name "Metaflex") with a fineness of 165 dtex and a filament number of 60 strands at a rate of 200 twists per 1m (twist coefficient 26). Adhesive coating liquid 1 was applied with a paste ratio of 59% by mass. Otherwise, the same procedure as in Example 1 was followed to obtain the filamentous adhesive of Example 6.

[0117] <Example 7> As the core material, a multifilament yarn was prepared by twisting silver-coated polyester fiber (SEIREN Corporation trade name "Metaflex") with a fineness of 165 dtex and a filament number of 60 at a rate of 500 twists per 1m (twist coefficient 64). Adhesive coating liquid 1 was applied with a paste ratio of 56% by mass. Otherwise, the same procedure as in Example 1 was followed to obtain the filamentous adhesive of Example 7.

[0118] <Example 8> As the core material, a multifilament yarn was prepared by twisting silver-coated polyester fiber (SEIREN Corporation trade name "Metaflex") with a fineness of 33 dtex and a filament number of 12 strands at a rate of 420 twists per 1m (twist coefficient 24). Adhesive coating liquid 1 was applied with a paste ratio of 57% by mass. Otherwise, the same procedure as in Example 1 was followed to obtain the filamentous adhesive of Example 8.

[0119] <Example 9> As the core material, a multifilament yarn was prepared by twisting silver-coated polyester fiber (SEIREN Corporation trade name "Metaflex") with a fineness of 99 dtex and a filament number of 36 at a rate of 250 twists per 1m (twist coefficient 25). Adhesive coating liquid 1 was applied with a paste ratio of 60% by mass. Otherwise, the same procedure as in Example 1 was followed to obtain the filamentous adhesive of Example 9.

[0120] <Example 10> As the core material, a multifilament yarn was prepared by twisting silver-coated polyester fiber (SEIREN Corporation trade name "Metaflex") with a fineness of 264 dtex and a filament number of 96 strands at a rate of 150 twists per 1m (twist coefficient 24). Adhesive coating liquid 1 was applied with a paste ratio of 64% by mass. Otherwise, the same procedure as in Example 1 was followed to obtain the filamentous adhesive of Example 10.

[0121] <Example 11> The core material is made by bundling four nickel-chromium wires (0.2 mm) together. Adhesive coating liquid 1 is applied by liquid immersion without using a coating roller to obtain a filamentous adhesive with a paste ratio of 18% by mass. Otherwise, the same procedure as in Example 1 is followed to obtain the filamentous adhesive of Example 11.

[0122] <Comparative Example 1> As the core material, a multifilament yarn made of polyethylene terephthalate (PET) fibers with a fineness of 167 dtex and a filament number of 48 was twisted at a rate of 190 twists per 1m to obtain a filamentous adhesive with a paste weight of 44% by mass. Otherwise, the same procedure as in Example 1 was followed to obtain the filamentous adhesive of Comparative Example 1.

[0123] <Comparative Example 2> Prepare the filamentous adhesive used in Comparative Example 1, and copper sulfide coated nylon fibers with a fineness of 235 dtex and a number of 15 filaments as conductive fibers.

[0124] Using a twisting machine (Olympus trade name "STRING-II high-speed rotary twisting machine"), the filamentous adhesive and conductive fibers were twisted together at a rate of 30 twists per 1m to form a composite of Comparative Example 2, which has a structure in which conductive fibers are wound around the filamentous adhesive.

[0125] <Comparative Example 3> The core material was made of nickel-chromium wire (0.2 mm in diameter). The adhesive coating liquid 1 was applied by liquid immersion without the use of a coating roller to obtain a filamentous adhesive with a paste ratio of 12% by mass. Otherwise, the same procedure as in Example 1 was followed to obtain the filamentous adhesive of Comparative Example 3.

[0126] (Methods for evaluating the physical properties of filamentous adhesives) For each filamentous adhesive of Examples 1-11 and Comparative Examples 1-3 (for Comparative Example 2, it was a composite of filamentous adhesive and conductive fiber), the compression ratio, shear force (an indicator of adhesive strength), and resistance value in the Z-axis direction (Z-axis resistance value) were measured as follows. The results are shown in Tables 1-2.

[0127] Compression ratio A filamentous adhesive with a length of 25 mm was prepared and clamped between two PET films (thickness: 50 μm) as a sample. For this sample, a Micro Autosampler (manufactured by Shimadzu Corporation) was used to press the filamentous adhesive against the width of the filamentous adhesive for 10 seconds at a pressure of 0.35 MPa. The compression ratio of the filamentous adhesive at this time was calculated using the following formula (1). It should be noted that the test was conducted at 23°C.

[0128] Compression ratio [%] = {(Height of the sample when compressed for 10 seconds at a pressure of 0.35 MPa) - (Thickness of PET film) × 2} × 100 / (Height of the filamentous adhesive before compression) ... (1) [Shear force] First, prepare two SUS304BA boards, each 30mm x 60mm in size.

[0129] A 100mm long filament adhesive was attached to one of the SUS304BA boards in a square shape with sides of 25mm. Then, another SUS304BA board was attached and pressed together with a pressure of 0.35MPa for 10 seconds. It should be noted that the test was conducted at 23°C.

[0130] Thirty minutes after the crimping, the shear force (N) was measured by using a tensile testing machine (Shimadzu Autograph AG-100M2 manufactured by Shimadzu Corporation) at a peeling speed of 300 mm / min.

[0131] [Z-axis resistance value] First, prepare two copper foil plates, each 30mm x 60mm in size.

[0132] like Figure 3 As shown, a 100mm long filament adhesive 10 is attached to one of the copper foil boards (copper foil board 1) in a square shape with a side length of 25mm. Then, another copper foil board (copper foil board 1) is attached and pressed with a pressure of 0.35MPa for 10 seconds.

[0133] Thirty minutes after crimping, clamp terminals 20 are connected to both ends of the bonded copper foil plates, a voltage of 0.4V is applied, the current flowing through is measured, and the resistance value of the filamentous adhesive 10 in the thickness direction (Z-axis direction), which is approximately orthogonal to the length direction, is calculated. It should be noted that a three-dimensional diagram showing the state with two copper foil plates bonded together is provided below. Figure 3 (a) will Figure 3 The cross-sectional diagram of line AA in (a) is shown in Figure 3 (b). In addition, the determination was performed at room temperature (23°C).

[0134] (Resistance value of the core material along its length (X-axis)) The core material used in each embodiment and comparative example is fixed 100 mm apart using clip-on terminals.

[0135] Apply a voltage of 0.4V, calculate the resistance value based on the current flowing through it, and use it as the resistance value of the core material along its length (X-axis direction).

[0136] [Table 1] Table 1 [Table 2] Table 2 Regarding the filamentous adhesive of Comparative Example 1, which uses insulating PET fibers as the core material, although the shear force is 0.80 [MPa], indicating sufficient adhesive force, the filamentous adhesive itself is insulating.

[0137] Regarding the composite of Comparative Example 2, which is formed by winding conductive fibers onto the filamentous adhesive used in Comparative Example 1, although the Z-axis resistance of the composite is 5.0 × 10⁻⁶... 3 [Ω / 100mm], exhibiting sufficient conductivity, but with a shear strength as low as 0.12 [MPa], indicating insufficient adhesion. This is presumably because a portion of the surface of the filamentous adhesive is covered by conductive fibers wound around it, resulting in numerous non-adhesive areas on the surface.

[0138] Regarding the filamentary adhesive of Comparative Example 3, which uses a single-wire nickel-chromium wire (monofilament) as the core material, although the Z-axis resistance of the filamentary adhesive is 1.5 × 10⁻⁶... 1 The filament adhesive exhibits sufficient conductivity ([Ω / 100mm]), but its shear strength is as low as 0.15 [MPa], resulting in insufficient adhesion. Furthermore, the compressibility of the filament adhesive is as low as 5 [%.] It is speculated that when the substrate (SUS304BA board) is pressed onto the filament adhesive, the core material, composed of single-wire nickel-chromium wire (monofilament), is difficult to deform, reducing the compressibility of the filament adhesive and decreasing the contact area with the substrate (SUS304BA board), thus reducing adhesion.

[0139] On the other hand, the filamentous adhesives of Examples 1-11 all exhibited high shear strength and sufficient adhesive force. This is presumably because the core material is composed of multifilaments, which makes it easy for the core material to deform when the substrate (SUS304BA board) is pressed onto the filamentous adhesive, thus increasing the contact area with the substrate (SUS304BA board).

[0140] Furthermore, regarding the filamentous adhesives of Examples 1-11, the resistivity in the Z-axis direction is low, and they all exhibit excellent conductivity when pressed onto the substrate (copper foil). This is presumably due to the use of a core material with high conductivity and an appropriate adhesive ratio (paste ratio). Additionally, it is presumed that because a multifilament core material is used, the core material is easily deformed when the substrate (copper foil) is pressed onto the filamentous adhesive, allowing for easy contact between the substrate (copper foil) and the core material, resulting in a low resistance value.

[0141] Furthermore, the filamentous adhesive of Example 11, which uses an article made of four bundled nickel-chromium wires as the core material, exhibits higher adhesive strength compared to the filamentous adhesive of Comparative Example 3, which uses a core material made of a single nickel-chromium wire (monofilament).

[0142] It should be noted that, for the filamentous adhesives of Examples 1-10, which use multifilament yarns composed of copper sulfide-coated nylon fibers or silver-coated polyester fibers as the core material, a higher adhesive strength is observed compared to the filamentous adhesive of Example 11, which uses an article composed of four nickel-chromium wires bundled together as the core material. This is presumably because, in the filamentous adhesives of Examples 1-10, the use of more flexible metal-coated fibers as the core material results in a higher compressibility of the filamentous adhesive, leading to a larger contact area with the adherend (SUS304BA board), thus exhibiting higher adhesive strength.

[0143] The various embodiments have been described above with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to these examples. Those skilled in the art will understand that various modifications or alterations will naturally arise within the scope of the claims, and these naturally fall within the technical scope of the present invention. Furthermore, the constituent elements in the above embodiments can be arbitrarily combined without departing from the spirit of the invention.

[0144] It should be noted that this application is based on Japanese patent application (Japanese Patent Application No. 2023-54107) filed on March 29, 2023, the contents of which are incorporated herein by reference.

[0145] Explanation of reference numerals in the attached figures 1: Copper foil board 10: Filamentous adhesive 11: Core material 12: Adhesive 13: Filament 20: Clamp terminal 21: The first object to be glued 22: The second object to be glued

Claims

1. A filamentous adhesive comprising a conductive core having multiple filaments and an adhesive coating the longitudinal surface of the core. The Z-axis resistivity of the filamentous adhesive, measured under the following conditions, is 1.0 × 10⁻⁶. 6 Below [Ω / 100mm] (condition) Two copper foil plates are bonded together using the filamentous adhesive. After pressing with a pressure of 0.35 MPa for 10 seconds and then for 30 minutes, the resistance value of the filamentous adhesive in the Z-axis direction is measured. Here, the Z-axis direction refers to the direction in which pressure is applied to the filamentous adhesive when the two copper foil plates are pressed together. It should be noted that the measurement is performed at 23°C.

2. The filamentous adhesive as described in claim 1, wherein the compression ratio is 13% or more when compressed at 0.35 MPa for 10 seconds at 23°C.

3. The filamentous adhesive as described in claim 1 or 2, wherein, The core material comprises metal-coated fibers with a surface layer formed of resin and coated with metal.

4. The filamentous adhesive as described in claim 1 or 2, wherein, The adhesive contains a surfactant.

5. The filamentous adhesive as described in claim 1 or 2, wherein, The diameter of the filamentous adhesive is less than 1 mm.

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