Method for manufacturing a bonded body and a bonded body

Abstract

To provide a method for producing a bonded object in which a plurality of members are bonded together, which can cope with diversification of a shape of a bonded region and have a small environmental load.SOLUTION: There is provided a method for producing a bonded object by bonding a plurality of members to each other with a pressure-sensitive adhesive yarn, in which the plurality of members each have a bonding region to be bonded, at least some of which has a bent shape, and the plurality of members are bonded to each other with the pressure-sensitive adhesive yarn which has been bent so as to conform to a shape of the bonding region.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a bonded body and the bonded body. [Background technology]

[0002] When bonding multiple items together, a shaped adhesive (for example, double-sided adhesive tape) may be used instead of a liquid adhesive due to requirements such as preventing dripping and improving workability.

[0003] Furthermore, when multiple items are bonded together using an adhesive, the shape of the area where the items are bonded together via the adhesive (hereinafter also referred to as the "bonding area") may vary depending on the items being bonded together. For example, in electronic devices such as smartphones, there are cases where a narrower bonding area is required when bonding components constituting the electronic device due to demands for miniaturization and design considerations. For example, when fixing the cover glass of a smartphone, a narrower bonding area is particularly required to achieve bezel-less designs. Furthermore, depending on the shape of the articles to be bonded, it may be necessary to make the bonding area into a complex shape such as a curved shape.

[0004] To meet the demand for a narrower bonding area, it is conceivable to cut a double-sided adhesive tape into thin strips, but this method has limitations on the narrower width. Furthermore, narrowing the double-sided adhesive tape may make it more susceptible to twisting, which may result in poor handling. Furthermore, double-sided adhesive tape is not suitable for application to curved shapes. Due to these problems, the method of cutting a double-sided adhesive tape into thin strips and using it cannot adequately meet the demand for a more diverse shape of bonding area.

[0005] As a method for meeting the demand for a variety of shapes of the lamination area, there is a method in which a double-sided pressure-sensitive adhesive film is cut into a desired shape by punching. For example, Patent Document 1 discloses an adhesive film with excellent cuttability, that is, an adhesive film in which the adhesive is prevented from forming strings when cut. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2017 / 064925 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the method of punching double-sided PSA film has the problem that a large portion of the resulting adhesive body is discarded, which places a heavy burden on the environment. In recent years, there has been a strong demand for reducing the environmental burden in order to realize a sustainable society, but the method of punching double-sided PSA film cannot meet this demand.

[0008] The present invention has been made in consideration of the above, and aims to provide a method for manufacturing a bonded structure in which multiple components are bonded together, which can accommodate a variety of shapes of bonding areas and has a low environmental impact. Another object of the present invention is to provide a bonded body produced by the method. [Means for solving the problem]

[0009] The method for manufacturing a bonded body of the present invention, which solves the above-mentioned problems, is a method for manufacturing a bonded body in which multiple components are bonded together using a thread-like adhesive, and the bonding area, which is the part where the multiple components are bonded together, has a curved shape in at least a part of it, and the thread-like adhesive is bent to match the shape of the bonding area to bond the multiple components together. In one embodiment of the method for producing a conjugate of the present invention, the thread-like adhesive body may have an adhesive strength of 5 N / 22 cm or more as measured by the test described in the specification. In one embodiment of the method for producing a joined body of the present invention, the plurality of members may be members that constitute an electronic device. Furthermore, the bonded structure of the present invention, which solves the above-mentioned problems, is a bonded structure in which multiple components are bonded together with a thread-like adhesive, and the bonding area, which is the part where the multiple components are bonded together, has a curved shape in at least a part of it, and the thread-like adhesive bends to match the shape of the bonding area and bonds the multiple components together. In one embodiment of the conjugate of the present invention, the thread-like adhesive body may have an adhesive strength of 5 N / 22 cm or more as measured by the test described in the specification. In one embodiment of the joined body of the present invention, the plurality of members may be members that constitute an electronic device. [Effects of the Invention]

[0010] The method for producing a bonded body of the present invention can accommodate a variety of shapes of bonding regions and has a low environmental impact. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is an exploded perspective view of a bonded body according to one embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view illustrating a method for evaluating the adhesive strength of the adhesive article of the present invention. [Figure 3] 3 is a cross-sectional view taken along line XX in FIG. 2. [Figure 4] FIG. 4 is a schematic diagram showing a state in which adherends are bonded together using an adhesive article having a core material made of multifilament yarn. [Figure 5] FIG. 5 is a schematic diagram showing a state in which adherends are bonded together using an adhesive article having a core material made of multifilament yarn. DETAILED DESCRIPTION OF THE INVENTION

[0012] FIG. 1 shows an exploded perspective view of a bonded body according to an embodiment of the present invention. The manufacturing method of the joined body 1 according to an embodiment of the present invention is a manufacturing method of the joined body 1 in which a plurality of components (components 2A, 2B) are bonded together using a thread-like adhesive 3, and the bonding region 4, which is the part where the plurality of components are bonded together, has a curved shape at least in part, and the thread-like adhesive 3 is bent to match the shape of the bonding region 4 to bond the plurality of components together. Furthermore, the bonded body 1 according to an embodiment of the present invention is a bonded body 1 in which multiple components (components 2A, 2B) are bonded together using a thread-like adhesive 3, and the bonding region 4, which is the part where the multiple components are bonded together, has a curved shape at least in part, and the thread-like adhesive 3 is bent to match the shape of the bonding region 4 and bond the multiple components together. Hereinafter, a method for manufacturing a bonded body of the present invention and embodiments of the bonded body will be described in detail. However, the present invention is not limited to the embodiments described below. Furthermore, in the drawings, components and parts that perform the same function may be denoted by the same reference numerals, and redundant explanations may be omitted or simplified. Furthermore, the embodiments shown in the drawings are schematic in order to clearly explain the present invention, and do not necessarily accurately represent the size or scale of an actual product.

[0013] [Thread-like adhesive substance] First, the thread-like adhesive body used in the method for producing a bonded body of this embodiment will be described in detail. The term "filiform" refers to a material whose longitudinal length is sufficiently longer than its width. 、 The ratio of the length of the major axis (the longest axis passing through the center of gravity of the cross-sectional shape) to the length of the minor axis (the shortest axis passing through the center of gravity of the cross-sectional shape) in the cross-sectional shape perpendicular to the longitudinal direction (hereinafter also referred to as "cross-sectional shape") (major axis / minor axis) but It means a shape with a number of strands of 10 or less, even more preferably 5 or less, and particularly preferably 3 or less, and also means a state in which it can be bent in various directions and angles like a thread. Since the thread-like adhesive body can be bent in various directions and angles, it can be bent to match the shape of the bonding area, and therefore can accommodate a variety of shapes of bonding areas. Furthermore, when a thread-like adhesive body is used, no waste is generated as in the case of using an adhesive body obtained by punching a double-sided adhesive film, and therefore the environmental load can be reduced.

[0014] The cross-sectional shape of the thread-like adhesive body is typically circular, but is not limited thereto and may be various shapes other than circular, such as elliptical, polygonal, etc. Furthermore, the length and thickness of the thread-like adhesive body in this embodiment are not particularly limited and may be adjusted appropriately depending on the application.

[0015] The adhesive threads may comprise a core material and an adhesive layer made of an adhesive that coats the circumferential surface of the core material, or may comprise only an adhesive without a core material. From the viewpoints of strength, handling, and adhesive force, it is preferable that the adhesive threads comprise a core material.

[0016] A thread-like adhesive body consisting of only an adhesive can be obtained, for example, by applying the adhesive in a line shape onto a separator and, if necessary, drying it by heating. Furthermore, a thread-like adhesive body having a core material can be obtained, for example, by applying a pressure-sensitive adhesive composition to the surface of a core material by dipping, immersion, coating, etc., and optionally drying by heating. The pressure-sensitive adhesive composition can be applied using a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater.

[0017] The type of adhesive used is not particularly limited, and examples thereof include acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluorine-based adhesives, and epoxy adhesives. Among these, rubber adhesives and acrylic adhesives are preferred from the standpoint of adhesiveness, with acrylic adhesives being particularly preferred. Note that only one type of adhesive may be used alone, or two or more types may be used in combination.

[0018] Acrylic adhesives are primarily composed of polymers of monomers that contain alkyl (meth)acrylate esters such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, and isononyl acrylate as the main component, with modifying monomers such as acrylonitrile, vinyl acetate, styrene, methyl methacrylate, acrylic acid, maleic anhydride, vinylpyrrolidone, glycidyl methacrylate, dimethylaminoethyl methacrylate, hydroxyethyl acrylate, and acrylamide added as needed.

[0019] Rubber-based adhesives are made primarily from rubber polymers such as natural rubber, styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, styrene-butadiene rubber, polybutadiene, polyisoprene, polyisobutylene, butyl rubber, chloroprene rubber, and silicone rubber.

[0020] These adhesives may also be appropriately blended with various additives such as tackifying resins such as rosin-based, terpene-based, styrene-based, aliphatic petroleum-based, aromatic petroleum-based, xylene-based, phenol-based, coumarone-indene-based, and hydrogenated versions of these, as well as crosslinking agents, viscosity modifiers (thickeners, etc.), leveling agents, release modifiers, plasticizers, softeners, fillers, colorants (pigments, dyes, etc.), surfactants, antistatic agents, preservatives, antioxidants, UV absorbers, antioxidants, and light stabilizers.

[0021] The adhesive may be either a solvent-based adhesive or a water-dispersed adhesive, with water-dispersed adhesives being preferred because they allow high-speed coating, are environmentally friendly, and have minimal effects on the core material (swelling, dissolution) due to the solvent.

[0022] In a thread-like adhesive body having a core material, from the viewpoint of adhesive strength, it is preferable that a large amount of adhesive is attached to the core material. Specifically, the amount of adhesive attached (weight of adhesive layer per unit length) is preferably 2 mg / m or more, more preferably 5 mg / m or more, and even more preferably 8 mg / m or more. On the other hand, if the amount of adhesive attached is excessive, the adhesive must be applied to the core material multiple times during the manufacturing process, and the applied adhesive takes a long time to dry, resulting in low manufacturing efficiency. Therefore, the amount of adhesive attached is preferably 200 mg / m or less, more preferably 180 mg / m or less, and even more preferably 160 mg / m or less.

[0023] The core material in a thread-like adhesive body having a core material is not particularly limited in shape or material as long as it is a thread-like member, and may be adjusted appropriately depending on the required properties such as strength, weight, hardness, etc. The cross-sectional shape of the core material is typically circular, but it can also be various other shapes such as oval or polygonal. The core material may be a monofilament consisting of a single filament, or a multifilament consisting of multiple filaments, or may be a spun yarn, a processed yarn that has been subjected to crimping or bulking processing, generally referred to as textured yarn, bulky yarn, or stretch yarn, a hollow yarn, or a yarn that is a combination of these by twisting them together, etc. The thickness of the core material is not particularly limited, and may be adjusted appropriately together with the thickness of the adhesive layer so that the thickness of the thread-like adhesive body is appropriate depending on the width of the gap.

[0024] The material for the core may be selected appropriately depending on the required properties such as strength, weight, hardness, etc. Examples of materials that can be used for the core include rayon, cupra, acetate, promix, nylon, aramid, vinylon, vinylidene, polyvinyl chloride, polyester, acrylic, polyethylene (PE), polypropylene (PP), polyolefins such as ethylene-propylene copolymer and ethylene-vinyl acetate copolymer, polyesters such as polyethylene terephthalate (PET), various polymeric materials such as vinyl chloride resin, vinyl acetate resin, polyimide resin, polyamide resin, fluororesin, polyurethane, polychlor, and polylactic acid; various rubbers such as natural rubber and synthetic rubbers such as polyurethane; inorganic materials such as glass, carbon materials, and metals; natural materials such as cotton and wool; and foams such as foamed polyurethane and foamed polychloroprene rubber.

[0025] The core material may contain various additives, such as fillers (inorganic fillers, organic fillers, etc.), antioxidants, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, plasticizers, colorants (pigments, dyes, etc.), etc. The surface of the core material may be subjected to known or conventional surface treatments, such as corona discharge treatment, plasma treatment, or application of a primer.

[0026] In a thread-like adhesive body having a core material, the core material does not necessarily have to be entirely coated with an adhesive layer on its periphery, and may have a portion that does not have an adhesive layer as long as the effects of the present invention are achieved. Furthermore, the end surface of the core material may or may not be coated with an adhesive layer. For example, if the adhesive body is cut during manufacturing or use, the end surface of the core material may not be coated with an adhesive layer.

[0027] In order to replace bonding that has conventionally been performed using adhesive bodies obtained by punching an adhesive film with bonding using adhesive threads, it is preferable that the adhesive threads have high adhesive strength. The adhesive strength of the thread-like adhesive body can be evaluated, for example, by the method shown below. (Method for evaluating adhesive strength) First, a first member and a second member as described below are prepared. First component: rectangular acrylic plate with a short side of 50 mm, a long side of 60 mm, and a thickness of 3 mm Second component: A rectangular polycarbonate resin plate with a short side of 80 mm, a long side of 110 mm, and a thickness of 10 mm, with a rectangular slit (short side 30 mm, long side 40 mm) in the center. Next, the adhesive thread is attached along the periphery of one side of the first member, and the first and second members are bonded together so that the center of the first member is aligned with the center of the slit in the second member, and then the bonded members are pressed together at 2 kg for 10 seconds to obtain a bonded assembly. A perspective view of the bonded assembly is shown in Figure 2, and a cross-sectional view taken along line AA in Figure 2 is shown in Figure 3. Then, the second member is fixed in place, and a load is applied through the slit to the center of the first member in the direction that separates the first and second members, as shown in Figure 3. The maximum load observed until the first and second members separate is measured. This measured maximum load is taken as the adhesive strength.

[0028] The adhesive strength of the thread-like adhesive body measured by the above method is preferably 5 N / 22 cm or more, more preferably 10 N / 22 cm or more, even more preferably 15 N / 22 cm or more, even more preferably 20 N / 22 cm or more, and particularly preferably 25 N / 22 cm or more.

[0029] In order to achieve high adhesive strength, it is particularly preferred that the thread-like adhesive body comprises a multifilament thread as a core material. The adhesive strength (how difficult it is to separate the articles) when multiple articles are bonded together with adhesive threads is greatly affected by the contact area between the adhesive threads and the articles. 4 shows a schematic diagram of a bonded structure 11 in which articles 12A and 12B are bonded together using a thread-like adhesive body 13 having a core material made of multifilament yarn. When articles are bonded together using a thread-like adhesive body 13 having a multifilament yarn as a core material, the filaments that make up the core material spread apart, and the core material deforms and collapses, allowing articles 12A and 12B to come into contact with the thread-like adhesive body over a wide area, resulting in high adhesive strength. For the reasons stated above, the thread-like adhesive body 13 having a multifilament yarn as a core material exhibits higher adhesive strength than adhesive articles having a core material made of a monofilament, even though the thickness (fineness) of the core material is similar.

[0030] When a multifilament yarn is used as a core material, the number of filaments constituting the multifilament is preferably 4 or more, more preferably 10 or more, even more preferably 15 or more, and particularly preferably 20 or more, from the viewpoint of adhesive strength. On the other hand, if the thickness (fineness) of the core material is kept at the same level, as the number of filaments constituting the core material increases, each filament becomes thinner (fineness decreases). If each filament becomes too thin, the strength of the core material may decrease and handling properties may be impaired. Therefore, the number of filaments constituting the core material is preferably 300 or less.

[0031] Furthermore, the multifilament yarn may be a twisted yarn, which is a twisted yarn, or an untwisted yarn, which is not twisted. That is, the multifilament yarn may have a twist count of more than 0 turns / m or 0 turns / m. Furthermore, the multifilament yarn may be a yarn obtained by combining multiple twisted or untwisted multifilaments together, with or without twisting.

[0032] When a force is applied in a peeling direction between articles bonded together using a thread-like adhesive having a multifilament yarn as a core material, the filaments spread, as shown in Figure 5, and the core material deforms in the thickness direction (direction perpendicular to the longitudinal direction) so as to stretch parallel to the applied force. However, if the shape of the core material becomes too distorted, stress will concentrate in the distorted parts, making these parts more likely to become the starting point for peeling. Therefore, to achieve even better adhesive strength, it is preferable that the filaments constituting the core material have a certain degree of cohesion. As mentioned above, the core material may be either untwisted or twisted yarn, but to impart a certain degree of cohesion to the filaments constituting the core material, the core material is preferably twisted. Specifically, the twist number of the core material is preferably 30 times / m or more, more preferably 60 times / m or more, and even more preferably 90 times / m or more. On the other hand, in order to allow the core material to deform sufficiently when multiple articles are bonded together and to increase the amount of adhesive attached per unit length, it is preferable that the twist of the core material is not too strong. Therefore, the number of twists of the core material is preferably 3000 times / m or less, more preferably 1500 times / m or less, even more preferably 800 times / m or less, and particularly preferably 250 times / m or less.

[0033] Furthermore, if the core material is twisted, it is preferable to also control the twist coefficient, expressed by the following formula (A), from the same perspective as above. The twist coefficient is an index used to discuss the effects of twisting (such as the effects on the core material's cohesion, ease of deformation, and adhesive adhesion amount) regardless of the thickness of the core material. In other words, the effect of the number of twists on the core material differs depending on the thickness of the core material, but if the twist coefficient is the same, the effect of twisting on the core material will be the same regardless of the thickness of the core material. The twist coefficient of the core material is preferably 0 or more, more preferably more than 0, and is preferably 200 or less, more preferably 100 or less, and even more preferably less than 50.

[0034]

number

[0035] In the formula (A), K is the twist coefficient, T is the number of twists (unit: [turns / m]), and D is the fineness (unit: [dtex]).

[0036] From the viewpoint of adhesive strength, the filaments forming the core material are preferably chemical fibers, particularly polyester or nylon. Chemical fibers are less likely to fluff and become distorted. Therefore, when the filaments forming the core material are chemical fibers, peeling is less likely to occur and excellent adhesive strength is exhibited.

[0037] The filaments forming the core material may be hollow fibers. Generally, hollow fibers are flexible in the thickness direction and easily deformable, so that the core material obtained using hollow fibers is also flexible in the thickness direction and easily deformable. Therefore, when hollow fibers are used as the filaments forming the core material, the aforementioned crushing deformation of the core material is more likely to occur. Furthermore, if the core material is highly flexible, when force is applied in a direction in which adherends bonded together using the adhesive article are pulled apart, stress due to deformation of the core material is more likely to be dispersed, so stress is less likely to be applied to the interface (adhesive surface) between the adhesive article and the adherend, and peeling is less likely to occur. For these reasons, when hollow fibers are used as the filaments forming the core material, adhesive articles with particularly excellent adhesive strength can be obtained. In addition, since hollow fibers are generally brittle, when hollow fibers are used as filaments forming the core material, it is preferable to use them without twisting them.

[0038] In order to reduce the environmental load, the thread-like adhesive body preferably contains a biomass-derived component. In this specification, a biomass-derived component refers to a component derived from a renewable organic resource. Typically, it refers to a component derived from a biological resource that can be sustainably reproduced in the presence of sunlight, water, and carbon dioxide. Therefore, components derived from fossil resources that are depleted through use after mining (fossil resource-based materials) are excluded. For example, a component derived from a plant is a biomass-derived component. Furthermore, non-biomass-derived components refer to components other than biomass-derived components.

[0039] The biomass degree can be used as an indicator of the content of biomass-derived components in the thread-like adhesive body. The biomass content of a thread-like adhesive body is the ratio of the weight of biomass-derived components contained in the thread-like adhesive body to the total weight of the thread-like adhesive body, and is calculated using the following formula: The same applies to the biomass content of the core material and the adhesive, which are each calculated using the following formulas. Biomass content of the thread-like adhesive body [%] = 100 × (weight of biomass-derived components contained in the thread-like adhesive body [g]) / (total weight of the thread-like adhesive body [g]) Biomass content of core material [%] = 100 × (weight of biomass-derived components contained in core material [g]) / (total weight of core material [g]) Biomass content of adhesive [%] = 100 × (weight of biomass-derived components contained in adhesive [g]) / (total weight of adhesive [g]) The biomass degree can be measured in accordance with ASTM D6866-18.

[0040] From the viewpoint of reducing the environmental load, the biomass degree of the thread-like adhesive body is preferably 10% or more, more preferably 25% or more, even more preferably 35% or more, even more preferably 50% or more, even more preferably 70% or more, even more preferably 90% or more, and most preferably 100%. The biomass degree of the thread-like adhesive body can be adjusted by adjusting the biomass degree of the core material and / or the adhesive layer. On the other hand, if the biomass degree of the core material or adhesive layer is increased too much in order to increase the biomass degree of the thread-like adhesive body, problems such as reduced strength and flexibility, reduced adhesive force, increased production costs, etc. Therefore, the biomass degree of the thread-like adhesive body is preferably 95% or less, more preferably 90% or less, and even more preferably 80% or less.

[0041] Possible methods for improving the biomass degree of the thread-like adhesive body include improving the biomass degree of the core material and improving the biomass degree of the pressure-sensitive adhesive layer. However, improving the biomass degree of the pressure-sensitive adhesive layer may result in a decrease in adhesive strength and an increase in production costs. Therefore, in improving the biomass degree of the thread-like adhesive body, it is preferable to improve the biomass degree of the core material in particular.

[0042] Examples of core materials containing biomass-derived components include natural fibers, such as plant fibers such as hemp and animal fibers such as silk and wool. Furthermore, examples of core materials containing biomass-derived components include biomass plastics, which are broadly classified into those made from biomass-derived components and those made from biomass-derived components and components derived from fossil resources. Examples of biomass plastics made from biomass-derived components include polylactic acid, polyethylene (bio-PE), nylon 11 (bio-PA11), nylon 1010 (bio-PA1010), and polyester (bio-PEs). Examples of biomass plastics made from biomass-derived components and fossil resource-derived components include polyethylene terephthalate (bioPET), polybutylene succinate (bioPBS), polybutylene terephthalate succinate, polyamide 610, 410, 510, 1012, 10T, 11T, MXD10 (bioPA610, 410, 510, 1012, 10T, 11T, MXD10), polycarbonate (bioPC), polyurethane (bioPU), aromatic polyester, unsaturated polyester, phenolic resin, epoxy resin, polylactic acid blend / PBAT, starch blend / polyester resin, etc.

[0043] From the viewpoint of reducing the environmental load, the biomass ratio of the core material is preferably 25% or more, more preferably 50% or more, even more preferably 70% or more, and most preferably 100%. On the other hand, if the biomass ratio of the core material is increased too much, problems such as reduced strength and flexibility, reduced adhesive strength, increased manufacturing costs, etc. Therefore, the biomass ratio of the core material is preferably 95% or less, more preferably 80% or less, and even more preferably 70% or less.

[0044] In order to reduce the environmental impact, it is also preferable that the core material of the thread-like adhesive body contains a recycled resin. In this specification, recycled resin refers to a resin obtained by recycling a resin product, and includes resins obtained by material recycling and chemical recycling. Material recycling refers to the process of recycling resin products such as waste plastics as raw materials for resin products after processing them such as crushing and dissolving them. Chemical recycling refers to the process of chemically breaking down waste plastic and other resin products through processes such as conversion into raw materials / monomers, blast furnace reducing agents, coke oven chemical raw materials, gasification, and oilification to obtain petroleum raw materials, which can then be reused as raw materials for resin products.

[0045] The type of recycled resin is not particularly limited and may be selected appropriately depending on the required properties, such as strength, mass, and hardness. Examples include materials containing various thermoplastic polymers, thermosetting polymers, and rubber, including polymeric materials such as rayon, cupra, acetate, promix, nylon, aramid, vinylon, vinylidene, polyvinyl chloride, polyester, acrylic, polyethylene (PE), polypropylene (PP), polyolefins such as ethylene-propylene copolymers and ethylene-vinyl acetate copolymers, polyester resins such as polyethylene terephthalate (PET), various polymeric materials such as vinyl chloride resins, vinyl acetate resins, polyimide resins, polyamide resins, fluororesins, polyurethanes, polychlors, and polylactic acids; various rubbers such as synthetic rubbers such as natural rubber and polyurethane; and foams such as polyurethane foam and polychloroprene rubber foam. Polyester resins are preferred, and polyethylene terephthalate (PET) is even more preferred.

[0046] The recycled resin may include a non-recycled resin, i.e., a commercially available polymer or a newly synthesized polymer. The type of non-recycled resin is not particularly limited, and examples include materials including polymeric materials such as various thermoplastic polymers, thermosetting polymers, and rubber. Thermoplastic polymers are preferred, and the same types of resins as the recycled resins described above are preferred, polyester resins are preferred, and polyethylene terephthalate (PET) is more preferred.

[0047] From the viewpoint of reducing the environmental load, the content of recycled resin in the core material is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 95% by mass or more.

[0048] Furthermore, when the core material is a multifilament yarn, all of the filaments constituting the multifilament yarn may contain biomass-derived components and / or recycled resins (hereinafter also referred to as "biomass-derived components, etc."), but only some of the filaments may contain biomass-derived components, etc., and other filaments may not contain biomass-derived components, etc. By adjusting the ratio of the number of filaments containing biomass-derived components, etc. to the total number of filaments constituting the multifilament yarn, the content ratio of biomass-derived components, etc., and various properties such as strength can be easily adjusted.

[0049] [Members, joints, and manufacturing methods for joints] The shape of the bonding area is not particularly limited as long as it is at least partially curved. An example of the shape of the bonding area is a frame shape that follows the outer shape of the bonding surface of one article (the surface facing another article in the bonded body). For example, when bonding a cover glass of a display or a cover glass of a camera such as a smartphone to a frame member, such a shape of the bonding area is required.

[0050] The type of material to be bonded is not particularly limited, but since there is a particular demand for thinner and more complex shapes in the bonding area when joining components of electronic devices, it is preferable that the material be a material that constitutes an electronic device. In addition to the cover glass and frame member described above, components constituting electronic devices include various wires (linear components), such as cables such as electric wires and optical fibers, LED fiber lights, and optical fiber sensors such as FBG (Fiber Bragg Gratings).When these components are attached and fixed to other components in a bent state, the shape of the attachment region also becomes a narrow, bent shape according to the shape of the linear component.

[0051] In the method for manufacturing a bonded body of this embodiment, it is preferable to first attach the adhesive threads to one member and then attach the other member to it. The method for attaching the adhesive threads to the members is not particularly limited, and a bonding machine (bonding device) may be used, the adhesive threads may be attached by hand, or the adhesive threads may be attached to a temporary support and then transferred to the member. In bonding the members together (that is, in producing a bonded body), a plurality of thread-like adhesive bodies may be used, but from the viewpoint of reducing the number of steps, it is preferable to use only one adhesive body. [Example]

[0052] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples in any way.

[0053] Example 1 (Preparation of Water-Dispersible Acrylic Pressure Sensitive Adhesive) A reaction vessel equipped with a condenser, nitrogen inlet tube, thermometer, and stirrer was charged with 40 parts by weight of ion-exchanged water, and nitrogen gas was introduced while stirring at 60°C for at least 1 hour to perform nitrogen substitution. 0.1 parts by weight of 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]n hydrate (polymerization initiator) was added to the reaction vessel. While maintaining the system at 60°C, Monomer Emulsion A was gradually added dropwise over 4 hours to allow the emulsion polymerization reaction to proceed. Monomer emulsion A was prepared by adding 98 parts by weight of 2-ethylhexyl acrylate, 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-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-503"), and 2 parts by weight of sodium polyoxyethylene lauryl sulfate (emulsifier) ​​to 30 parts by weight of ion-exchanged water and emulsifying them. After the dropwise addition of monomer emulsion A was completed, the system was maintained at 60°C for an additional 3 hours, cooled to room temperature, and then the pH was adjusted to 7 by adding 10% aqueous ammonia, yielding an acrylic polymer emulsion (water-dispersible acrylic polymer). For every 100 parts by weight of the acrylic polymer contained in the acrylic polymer emulsion, 20 parts by weight (solids) of a tackifier resin emulsion (manufactured by Arakawa Chemical Industries, Ltd., product name "E-865NT") was added. Furthermore, the pH was adjusted to 7.2 and the viscosity to 10 Pa·s using 10% by weight ammonia water as a pH adjuster and polyacrylic acid (manufactured by Toagosei Co., Ltd., product name "Aron B-500") as a thickener. In this way, a water-dispersible acrylic adhesive for the adhesive layer was obtained.

[0054] (Production of thread-like adhesive body) A multifilament yarn (280 dtex) made of 48 polyester yarns (filaments) twisted at 150 turns / m was used as the core material. A water-dispersible acrylic pressure-sensitive adhesive was applied to the core material by dipping so that the adhesive amount in the resulting pressure-sensitive adhesive article would be 22 mg / m, and then the core material was dried at 80°C for 5 minutes to form a pressure-sensitive adhesive layer, thereby obtaining a thread-like adhesive material of Example 1.

[0055] (Manufacturing of bonded body and evaluation of adhesive strength) The following first and second members were prepared. First component: rectangular acrylic plate with a short side of 50 mm, a long side of 60 mm, and a thickness of 3 mm Second component: A rectangular polycarbonate resin plate with a short side of 80 mm, a long side of 110 mm, and a thickness of 10 mm, with a rectangular slit (short side 30 mm, long side 40 mm) in the center. As shown in an oblique view in Figure 2 and a cross-sectional view along line 2X-X in Figure 3, the obtained thread-like adhesive body 23 (not shown in Figure 2) was attached along the periphery of one side of the first member 22A, and the first member 22A and the second member 22B were bonded together so that the center of the first member 22A and the center of the slit in the second member 22B were aligned, and the bonded members were pressed together at 2 kg for 10 seconds to obtain a bonded body. Next, the second member 22B was fixed, and a load was applied to the center of the first member 22A through the slit in a direction that would separate the first member 22A and the second member 22B, as shown in Figure 3. The maximum load observed until the first member 22A and the second member 22B separated was measured, and the measurement result was 27 N / 22 cm.

[0056] <Comparative Example 1> (Manufacturing adhesive bodies by cutting adhesive film) The center of a double-sided adhesive film (50 mm, long side 60 mm, thickness 0.2 mm) protected on both sides with a separator was cut off to obtain a frame-shaped adhesive body of Comparative Example 1 with a width of 0.3 mm. The weight of the obtained frame-shaped adhesive body was 0.01 mg, while the total weight of the discarded parts (separator and cut-off adhesive film) was 0.75 mg, i.e., about 98% of the total weight was discarded parts.

[0057] (Manufacturing of bonded body and evaluation of adhesive strength) A bonded structure was obtained in the same manner as in Example 1, except that the adhesive material of Comparative Example 1 was used in place of the adhesive thread of Example 1. Next, in the same manner as in Example 1, the maximum load observed until the first member and the second member were separated was measured, and the measurement result was 32 N / 22 cm.

[0058] In Comparative Example 1, although a bonded body was obtained in which the adhesive strength between the first and second members was high and the bonded region had a curved (frame-like) shape, a large amount of material was discarded in the manufacturing process of the adhesive body. In Example 1, the adhesive strength between the first and second members was comparable to that of Comparative Example 1, and a bonded body having a curved (frame-shaped) bonded region was obtained. In addition, no waste was generated during the manufacturing process of the adhesive body. [Explanation of symbols]

[0059] 1, 11 Joined body; 2A, 2B, 12A, 12B, 22A, 22B Components; 3, 13, 23 Thread-like adhesive; 4 Pasting area

Claims

1. A method for manufacturing a bonded body in which a plurality of members are bonded together using a string-like adhesive material, The thread-like adhesive body includes a core material and an adhesive layer made of an adhesive and covering the circumferential surface of the core material, the core material is a multifilament yarn having four or more filaments, The twist coefficient of the core material, represented by the following formula (A), is 0 or more and 200 or less, a bonding region where the plurality of members are bonded to each other has at least a partially curved shape; The method for manufacturing a bonded body includes bending the thread-like adhesive body to match the shape of the bonding area and bonding the multiple components together. [Equation 1] (In formula (A), K is the twist coefficient, T is the number of twists (unit: [turns / m]), and D is the fineness (unit: [dtex]).)

2. The method for producing a joined body according to claim 1 , wherein the thread-like adhesive body has an adhesive strength of 5 N / 22 cm or more as measured by the following test. (Method for measuring adhesive strength) First, prepare a first member, which is a rectangular acrylic plate with a short side of 50 mm, a long side of 60 mm, and a thickness of 3 mm, and a second member, which is a rectangular polycarbonate resin plate with a short side of 80 mm, a long side of 110 mm, and a thickness of 10 mm, with a rectangular slit (short side of 30 mm, long side of 40 mm) in the center. Next, the thread-like adhesive body is attached along the periphery of one surface of the first member, and the first member and the second member are bonded together so that the center of the first member coincides with the center of the slit in the second member, and then pressed together at 2 kg for 10 seconds to obtain a bonded body. Then, the second member is fixed, and a load is applied to the center of the first member through the slit in a direction that separates the first member and the second member, and the maximum load observed until the first member and the second member separate is measured, and this measured maximum load is taken as the adhesive strength.

3. The method for manufacturing a joined body according to claim 1 or 2, wherein the plurality of members are members constituting an electronic device.

4. A bonded structure in which a plurality of members are bonded together by a thread-like adhesive material, The thread-like adhesive body includes a core material and an adhesive layer made of an adhesive and covering the circumferential surface of the core material, the core material is a multifilament yarn having four or more filaments, The twist coefficient of the core material, represented by the following formula (A), is 0 or more and 200 or less, a bonding region where the plurality of members are bonded to each other has at least a partially curved shape; The adhesive threads are bent to fit the shape of the bonding area to bond the plurality of components together. [Equation 2] (In formula (A), K is the twist coefficient, T is the number of twists (unit: [turns / m]), and D is the fineness (unit: [dtex]).)

5. The bonded structure according to claim 4, wherein the thread-like adhesive body has an adhesive strength of 5 N / 22 cm or more as measured by the following test. (Method for measuring adhesive strength) First, prepare a first member, which is a rectangular acrylic plate with a short side of 50 mm, a long side of 60 mm, and a thickness of 3 mm, and a second member, which is a rectangular polycarbonate resin plate with a short side of 80 mm, a long side of 110 mm, and a thickness of 10 mm, with a rectangular slit (short side of 30 mm, long side of 40 mm) in the center. Next, the thread-like adhesive body is attached along the periphery of one surface of the first member, and the first member and the second member are bonded together so that the center of the first member coincides with the center of the slit in the second member, and then pressed together at 2 kg for 10 seconds to obtain a bonded body. Then, the second member is fixed, and a load is applied to the center of the first member through the slit in a direction that separates the first member and the second member, and the maximum load observed until the first member and the second member separate is measured, and this measured maximum load is taken as the adhesive strength.

6. The joined body according to claim 4 or 5, wherein the plurality of members are members that constitute an electronic device.

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