Thread-like adhesive and method for manufacturing a thread-like adhesive

Abstract

The present invention addresses the problem of providing a filamentous adhesive body having high impact resistance. The present invention relates to a filamentous adhesive body having an adhesive agent and a core that has multiple filaments, wherein the adhesive agent coats and impregnates the core, and the filamentous adhesive body contains 1 to 55 vol% of voids.

Description

Technical Field

[0001] The present invention relates to a filamentous adhesive and a method for producing the filamentous adhesive.

Background Art

[0002] When bonding two or more articles, an adhesive such as a double-sided adhesive tape may be used. However, a double-sided adhesive tape usually has a certain width and is not suitable when the shape of the articles to be bonded is complicated or when the width of the bonding area is narrow.

[0003] Therefore, a double-sided adhesive tape cut to a narrow width or a double-sided adhesive tape cut into a desired shape by punching is used.

[0004] However, a double-sided adhesive tape cut to a narrow width has problems such as low reworkability due to insufficient substrate strength, unsuitability for attachment to a curved article, and easy twisting of the front and back. Also, although a double-sided adhesive tape cut into a desired shape by punching does not have such problems, there are problems such as high labor costs for processing and high costs due to a large amount of waste generated during processing.

[0005] In order to solve the above problems, a filamentous adhesive is used. The filamentous adhesive has high reworkability, can be deformed into various shapes, and has no problem of deterioration in handling due to twisting because there is no concept of front and back. Also, the filamentous adhesive is easy to process and is advantageous in terms of cost.

[0006] As the filamentous adhesive, for example, Patent Document 1 discloses a filamentous adhesive characterized in that an adhesive is attached to a filamentous core material.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

[0008] However, according to the inventors' research, conventional filamentous adhesives, such as those disclosed in Patent Document 1, have the problem of low impact resistance.

[0009] This invention has been made in view of the above-mentioned conventional circumstances, and aims to solve the problem of providing a filamentous adhesive with high impact resistance. [Means for solving the problem]

[0010] The inventors of this invention conducted extensive research to solve the above problems and, as a result, discovered that the above problems could be solved by creating voids in the filamentous adhesive material, thus completing the present invention.

[0011] In other words, the present invention is as follows: <1> ~ <7> This concerns... <1> A thread-like adhesive having a core material with multiple filaments and an adhesive, The adhesive covers the core material and impregnates the core material. The aforementioned filamentous adhesive is a filamentous adhesive containing 1 to 55 volume percent of voids. <2> The following equation (1) is satisfied: <1> The thread-like adhesive described above. a / b ≥ 2 (1) In equation (1), a represents the length of the longest straight line that can be placed in the void, and b represents the length of the widest part in the cross-section obtained by cutting the filamentous adhesive perpendicular to the longitudinal direction. <3> The number of twists of the core material is 1 to 500 times / m. <1> or <2> The thread-like adhesive described above. <4> A method for manufacturing a filamentous adhesive having a core material with multiple filaments and an adhesive, The process includes applying a coating liquid containing the adhesive to the core material, Does not include the fiber opening process. A method for manufacturing a filamentous adhesive. <5>In the coating process, a roller is used, The production method of the filamentary adhesive body according to <4>, wherein the rotational speed of the roller is 0.3 to 5.0 times the feeding speed of the core material. <6>In the coating process, a tension of 6.0 mN / dtex or less is applied to the core material. The production method of the filamentary adhesive body according to <4> or <5>. <7>The viscosity of the coating liquid under the condition of a shear rate of 100 (1 / s) is 0.03 to 6 Pa·s, and the viscosity of the coating liquid under the condition of a shear rate of 0.1 (1 / s) is 2 to 140 Pa·s. The production method of the filamentary adhesive body according to any one of <4> to <6>.

Advantages of the Invention

[0012] The filamentary adhesive body of the present invention has high impact resistance and excellent reworkability.

Brief Description of the Drawings

[0013] [Figure 1] Figure 1 is a cross-sectional photograph of the filamentary adhesive body obtained in Example 2. [Figure 2] Figure 2 is a schematic diagram of the joined body used for evaluating the impact resistance in the examples.

Modes for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described in more detail, but the present invention is not limited to the following embodiments at all.

[0015] [Filamentary Adhesive Body] The filamentary adhesive body of the present invention has a core material having a plurality of filaments and an adhesive.

[0016] Here, the term "filamentary" means that the length in the longitudinal direction is sufficiently longer than the length in the width direction, and the ratio (long axis / short axis) of the length of the long axis to the length of the short axis in the cross-sectional shape is, for example, 200 or less, and also means a shape that can be bent in various directions and at various angles like a thread.

[0017] Note that the cross-sectional shape means the shape of a cross-section obtained by cutting an object perpendicularly to its longitudinal direction. The short axis means the shortest one among the axes passing through the centroid of the cross-sectional shape. The long axis means the longest one among the axes passing through the centroid of the cross-sectional shape. The ratio of the long axis to the short axis is preferably 100 or less, more preferably 50 or less, still more preferably 10 or less, particularly preferably 5 or less, and most preferably 3 or less.

[0018] Since the filamentous adhesive body of the present invention can be bent in various directions and at various angles, it can be bent according to the shape of the bonding region, and can cope with diversification of the shape of the bonding region.

[0019] <Core material> The filamentous adhesive body of the present invention has a core material. The core material is preferably filamentous.

[0020] The core material has a plurality of filaments and is a multifilament yarn obtained by combining or twisting the plurality of filaments. When the core material is a multifilament yarn, sufficient strength and stable physical properties can be obtained. As a result, a filamentous adhesive body with low quality variation, excellent strength, and excellent adhesive force can be obtained.

[0021] From the viewpoint of adhesive force, the number of filaments in the core material is preferably 2 or more, more preferably 20 or more, and particularly preferably 40 or more.

[0022] On the other hand, when the thickness (fineness) of the core material is kept at the same level, if the number of filaments increases, each filament becomes thinner (the fineness becomes smaller). If each filament becomes too thin, there is a risk of reducing the strength of the core material and the handling property. Therefore, the number of filaments is preferably 2000 or less, more preferably 1500 or less, and particularly preferably 1000 or less.

[0023] There are no particular limitations on the type of resin used for the filament; it can be appropriately selected according to the required properties such as strength, mass, and hardness. Examples include materials containing polymer materials such as thermoplastic polymers, thermosetting polymers, and rubber.

[0024] Specifically, polymer materials such as rayon, cupro, acetate, promix, nylon, aramid, vinylon, vinylidene, polyvinyl chloride, acrylic, polyolefin (polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, etc.), polyester resin (polyethylene terephthalate, etc.), vinyl chloride resin, vinyl acetate resin, polyimide resin, polyamide resin, fluororesin, polyurethane, polyclar, and polylactic acid can be used; rubber such as synthetic rubber (natural rubber, polyurethane, etc.); and foams such as foamed polyurethane and foamed polychloroprene rubber can be used. Among these, polyester resin is preferred, and polyethylene terephthalate is more preferred.

[0025] From the viewpoint of suppressing the impregnation of the adhesive into the core material, the filament content in the core material is preferably 10 to 100% by mass, more preferably 50 to 100% by mass, and particularly preferably 80 to 100% by mass.

[0026] The core material may contain various additives as needed, such as fillers (inorganic fillers, organic fillers, etc.), anti-aging agents, antioxidants, UV absorbers, antistatic agents, lubricants, plasticizers, and colorants (pigments, dyes, 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.

[0027] The form of the core material is not particularly limited and can be adjusted as appropriate according to the required properties such as strength, mass, and hardness. The cross-sectional shape of the core material is typically circular, but it can take on various other shapes, such as elliptical or polygonal.

[0028] The core material may have multiple filaments, and may be a yarn formed by twisting together filaments with spun yarn, processed yarn, hollow yarn, etc. Examples of processed yarns include those that have undergone crimping or bulking processes, generally referred to as textured yarn, bulky yarn, or stretch yarn.

[0029] The thickness of the core material is not particularly limited; it should be adjusted as needed so that the thickness of the thread-like adhesive is appropriate for the application.

[0030] Furthermore, the core material is preferably twisted once per meter or more. A twist count of once per meter or more facilitates the formation of the voids described later, improving the impact resistance of the filamentous adhesive. The core material is more preferably twisted 20 times per meter or more, and even more preferably 50 times per meter or more.

[0031] On the other hand, in order to allow the core material to deform sufficiently when bonding multiple articles together, and to increase the amount of adhesive applied per unit length, it is preferable that the twist of the core material not be too strong. Therefore, the number of twists of the core material is preferably 500 twists / m or less, more preferably 300 twists / m or less, and even more preferably 100 twists / m or less.

[0032] Furthermore, if the core material is twisted, it is preferable to control the twist coefficient K, which is expressed by the following formula (A), from the same viewpoint as above. The twist coefficient K is an index for discussing the effects of twisting (effects on the cohesiveness of the core material, ease of deformation, amount of adhesive adherence, etc.) 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 K is the same, it indicates that the effect of twisting on the core material is about the same regardless of the thickness of the core material.

[0033] The twist coefficient K is preferably 0 or greater, and more preferably greater than 0. On the other hand, if the twist coefficient K is 200 or less, the flexibility of the core material and, consequently, the filamentous adhesive is improved, making it easier to apply to complex shapes and narrow areas such as curved sections, bent sections, and uneven sections. Therefore, the twist coefficient K is preferably 200 or less, more preferably 100 or less, and even more preferably less than 50.

[0034]

number

[0035] In equation (A), K represents the twist coefficient, T represents the number of twists (twists / m), and D represents the fineness (dtex).

[0036] From the viewpoint of suppressing a decrease in the strength of the filamentous adhesive, the core material content in the filamentous adhesive is preferably 10% by mass or more, more preferably 20% by mass or more, and particularly preferably 30% by mass or more. Furthermore, from the viewpoint of suppressing the core material from coming out onto the surface, the core material content in the filamentous adhesive is preferably 90% by mass or less, more preferably 80% by mass or less, and particularly preferably 70% by mass or less.

[0037] <Adhesive> The filamentous adhesive material of the present invention has an adhesive. The adhesive coats the core material and is impregnated into the core material.

[0038] It is preferable that the adhesive covers the entire circumference of the longitudinal surface of the core material. The entire circumference of the core material's surface refers to the entire circumferential surface of the core material, meaning the entire 360° circumference of the core material's surface, centered on the longitudinal center line of the core material.

[0039] However, the end faces of the core material may or may not be covered with adhesive. For example, if the thread-like adhesive material is cut during manufacturing or use, the end faces of the core material may not be covered with adhesive.

[0040] By covering the entire circumference of the longitudinal surface of the core material with an adhesive, a thread-like adhesive with excellent strength can be obtained. This is presumably because the core material does not come into contact with the surface, preventing stress from concentrating on a part of the core material and causing it to break.

[0041] The coverage rate of the core material by the adhesive (area of ​​adhesive per unit area of ​​the core material surface (%)) is preferably 50 area % or more, more preferably 80 area % or more, even more preferably 90 area % or more, and particularly preferably 95 area % or more. If the coverage rate of the core material is 50 area % or more, the core material can be prevented from breaking, and a thread-like adhesive with excellent strength can be obtained.

[0042] The coverage rate of the core material can be calculated, for example, using an X-ray CT scanner (Xradia 520 Versa, Zeiss, tube voltage 60kV, tube current 83μA, pixel size 1.5μm / pixel). Specifically, 1601 continuous transmission images are taken of the entire circumference of the filamentous adhesive from 0° to 360°. The obtained images are reconstructed in 3D using image analysis software [ImageJ, AVIZO (Thermo Fisher Scientific)], and the core material, adhesive, and air are identified by trinarization and noise reduction based on their brightness. This identification is performed by checking the brightness of air and adhesive separately and setting a first threshold at their midpoint, and then checking the brightness of adhesive and core material separately and setting a second threshold at their midpoint. Using the images obtained by trinarization, the area of ​​the core material-air interface (interface 1) and the area of ​​the core material-adhesive interface (interface 2) are calculated, and the coverage rate is determined by the following formula. Coverage (%) = {Area of ​​interface 2 / (Area of ​​interface 1 + Area of ​​interface 2)} × 100

[0043] Note that the above interface 1 excludes the interface between the core material and the void in the filamentous adhesive of the present invention. Also, if the filament is a hollow fiber, the above interface 1 excludes the interface between the core material and the void inside the filament. Furthermore, interface 2 refers to the interface between the adhesive and air. Interface 2 excludes the interface between the adhesive and the voids in the filamentous adhesive of the present invention. Also, if the filament is a hollow fiber, interface 2 excludes the interface between the adhesive and the voids inside the filament.

[0044] Here, "the adhesive is impregnated into the core material" means that the adhesive is embedded between the multiple filaments in the core material. When the adhesive is impregnated into the core material, the adhesion between the adhesive and the core material is maintained, making it difficult for them to separate and improving the strength of the filamentous adhesive.

[0045] The type of adhesive is not particularly limited; for example, acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluorine adhesives, epoxy adhesives, etc., can be used.

[0046] Among these, acrylic adhesives and rubber adhesives are preferred in terms of tackiness, with acrylic adhesives being more preferred. Note that the adhesive may be used alone or in combination of two or more types.

[0047] Acrylic adhesives primarily consist of polymers made from alkyl (meth)acrylates such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, and isononyl acrylate, to which modifier monomers such as acrylonitrile, vinyl acetate, styrene, methyl methacrylate, acrylic acid, maleic anhydride, vinylpyrrolidone, glycidyl methacrylate, dimethylaminoethyl methacrylate, hydroxyethyl acrylate, and acrylamide are added as needed.

[0048] Rubber-based adhesives primarily consist of 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.

[0049] Furthermore, the adhesive may appropriately contain 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 hydrogenated derivatives, as well as various additives such as crosslinking agents, viscosity modifiers (thickeners, etc.), leveling agents, release modifiers, plasticizers, softeners, fillers, colorants (pigments, dyes, etc.), surfactants, antistatic agents, preservatives, anti-aging agents, UV absorbers, antioxidants, and light stabilizers.

[0050] Both solvent-based and water-dispersible adhesives can be used. However, water-dispersible adhesives are preferred because they allow for high-speed coating, are environmentally friendly, and have minimal impact on the core material (swelling, dissolution) due to the solvent.

[0051] The amount of adhesive applied (mass of adhesive 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 applied is excessive, it becomes necessary to apply the adhesive to the core material multiple times during the manufacturing process, and the drying time of the applied adhesive is long, resulting in low manufacturing efficiency. Therefore, the amount of adhesive applied is preferably 200 mg / m or less, more preferably 180 mg / m or less, and even more preferably 160 mg / m or less.

[0052] From the viewpoint of increasing the coverage rate of the core material, the adhesive content in the filamentous adhesive is preferably 10% by mass or more, more preferably 20% by mass or more, and particularly preferably 30% by mass or more. Furthermore, from the viewpoint of suppressing a decrease in the strength of the filamentous adhesive, the adhesive content in the filamentous adhesive is preferably 90% by mass or less, more preferably 80% by mass or less, and particularly preferably 70% by mass or less.

[0053] <Characteristics of thread-like adhesives> The filamentous adhesive material of the present invention contains 1 to 55% by volume of voids. Here, the above-mentioned void refers to the gap between multiple filaments in the core material. Furthermore, if the filament is a hollow fiber, the above-mentioned void does not include the void inside the filament.

[0054] The void content in the filamentous adhesive of the present invention (hereinafter sometimes referred to as "void ratio of the filamentous adhesive") is 1 volume% or more. That is, the adhesive does not impregnate all the filaments in the core material without any gaps, but rather voids exist between some of the filaments. When the void ratio of the filamentous adhesive is 1 volume% or more, the filamentous adhesive can deform and release stress when an impact is applied to it, thereby improving the impact resistance of the filamentous adhesive. The void ratio of the filamentous adhesive is preferably greater than 1 volume%, more preferably 3 volume% or more, and particularly preferably 5 volume% or more.

[0055] Furthermore, if the porosity of the filamentous adhesive is 55 volume% or less, the amount of adhesive impregnated into the core material will not be too small, the adhesion between the adhesive and the core material will be maintained, and the two will not peel off. The porosity of the filamentous adhesive is preferably 50 volume% or less, more preferably 47 volume% or less, even more preferably 45 volume% or less, particularly preferably 30 volume% or less, and most preferably 20 volume% or less. The porosity of the filamentous adhesive can be measured by the method described in the examples.

[0056] The thread-like adhesive of the present invention preferably satisfies the following formula (1). a / b ≥ 2 (1) In equation (1), a represents the length of the longest straight line that can be placed in the void, and b represents the length of the widest part in the cross-section obtained by cutting the filamentous adhesive perpendicular to the longitudinal direction.

[0057] When equation (1) above is satisfied, the uneven distribution of voids in the filamentous adhesive can be reduced, thereby improving the impact resistance of the filamentous adhesive. Furthermore, when equation (1) above is satisfied, friction between filaments increases during impact, and the impact energy is converted into thermal energy, thus improving the impact resistance of the filamentous adhesive. The value of a / b is preferably 2 or more, more preferably 3 or more, and particularly preferably 5 or more. The a / b value can be measured by the method described in the examples. The a / b value is for a thread-like adhesive with a length of 2.7 mm.

[0058] Furthermore, the thickness of the filamentous adhesive is preferably 50 to 2000 μm, and more preferably 100 to 1000 μm, from the viewpoint of strength and handling.

[0059] [Method for manufacturing thread-like adhesive material] The method for producing a filamentous adhesive of the present invention (hereinafter sometimes referred to as "the method for producing the present invention") includes a coating step of applying a coating liquid containing an adhesive to a core material.

[0060] The coating liquid can be applied to the core material by, for example, dipping, immersion, or coating, and then heated and dried as needed. Heat drying can be carried out, for example, under conditions of 80-90°C, preferably 100-110°C, for 3-4 minutes, preferably 5-6 minutes.

[0061] The coating liquid can be applied using conventional coaters such as gravure roll coaters, reverse roll coaters, kiss roll coaters, dip roll coaters, bar coaters, knife coaters, and spray coaters.

[0062] The manufacturing method of the present invention does not include a fiber-opening step. By omitting the fiber-opening step, the porosity of the filamentous adhesive material of the present invention can be kept within the range described above.

[0063] Furthermore, in the manufacturing method of the present invention, a roller is preferably used in the coating process, and the rotation speed of the roller is preferably 0.3 to 5.0 times the core material feed speed. By keeping the roller rotation speed within the above range, the unraveling of the core material is suppressed, and the void ratio of the filamentous adhesive material of the present invention can be easily kept within the above range.

[0064] The rotational speed of the roller is more preferably 0.4 to 4.0 times the core material feed speed, even more preferably 0.5 to 3.0 times, and particularly preferably 0.8 to 1.5 times.

[0065] Furthermore, it is preferable to apply a tension of 6.0 mN / dtex or less to the core material during the coating process. By applying a tension of 6.0 mN / dtex or less to the core material, the opening of the fibers in the core material is suppressed, making it easier to keep the void ratio of the filamentous adhesive material of the present invention within the range described above.

[0066] The tension applied to the core material is preferably 0.2 to 6.0 mN / dtex, and more preferably 0.4 to 5.0 mN / dtex.

[0067] Furthermore, the viscosity of the coating liquid at a shear rate of 100 (1 / s) (hereinafter sometimes referred to as "viscosity α") is preferably 0.03 Pa·s or higher, more preferably 0.05 Pa·s or higher, and even more preferably 0.07 Pa·s or higher, from the viewpoint of preventing the core material from being exposed due to the coating liquid not being applied to it.

[0068] Viscosity α is preferably 6 Pa·s or less, more preferably 5 Pa·s or less, and even more preferably 4 Pa·s or less, from the viewpoint of preventing the coating liquid from not flowing, resulting in lumps or unevenness on the core material, and thus preventing the core material from being exposed. Furthermore, viscosity α is predicted to be close to the viscosity of the coating solution during the coating process.

[0069] The viscosity of the coating liquid at a shear rate of 0.1 (1 / s) (hereinafter sometimes referred to as "viscosity β") is preferably 2 Pa·s or higher, more preferably 4 Pa·s or higher, and even more preferably 6 Pa·s or higher, from the viewpoint of preventing the coating liquid from being repelled and the core material from being exposed during the process from coating to drying.

[0070] From the viewpoint of leveling properties, viscosity β is preferably 140 Pa·s or less, more preferably 120 Pa·s or less, and even more preferably 100 Pa·s or less. Viscosity β indicates the degree of fluidity of the coating liquid from application to drying.

[0071] Viscosity α and viscosity β can be measured by the method described in the examples. [Examples]

[0072] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to the following examples.

[0073] <Example 1> (Preparation of coating solution 1) In a reaction vessel equipped with a condenser, nitrogen inlet tube, thermometer, and stirrer, 40 parts by mass of deionized water were added, and nitrogen gas was introduced while stirring at 60°C for more than 1 hour to purge the mixture with nitrogen. To this reaction vessel, 0.1 parts by mass of 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]n hydrate (polymerization initiator) was added. While maintaining the system at 60°C, the monomer emulsion A described below was gradually added dropwise over 4 hours to allow the emulsion polymerization reaction to proceed.

[0074] Monomer emulsion A was prepared by emulsifying 98 parts by mass of 2-ethylhexyl acrylate, 1.25 parts by mass of acrylic acid, 0.75 parts by mass of methacrylic acid, 0.05 parts by mass of lauryl mercaptan (chain transfer agent), 0.02 parts by mass of γ-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-503"), and 2 parts by mass of polyoxyethylene sodium lauryl sulfate (emulsifier) ​​with 30 parts by mass of ion-exchanged water.

[0075] After the dropwise addition of monomer emulsion A was complete, the system was kept at 60°C for a further 3 hours, cooled to room temperature, and then the pH was adjusted to 7 by adding 10% aqueous ammonia to obtain an acrylic polymer emulsion (water-dispersible acrylic polymer).

[0076] For every 100 parts by mass of the acrylic polymer contained in the above-mentioned acrylic polymer emulsion, 24 parts by mass of tackifying resin emulsion (manufactured by Arakawa Chemical Industries, Ltd., trade name "E-865NT") was added, based on solid content. Furthermore, deionized water was added to adjust the solid content concentration to 50% by mass to obtain coating solution 1.

[0077] (Manufacturing of thread-like adhesives) As the core material, we prepared a multifilament yarn consisting of one polyester fiber with a fineness of 165 dtex and 48 filaments, twisted 200 times per meter.

[0078] The viscosity of coating liquid 1 was set to that shown in Table 1, and the core material was coated by dipping using a coating roller rotating at the same speed as the dispensing speed. At that time, the core material was subjected to the tension shown in Table 1. After that, it was dried at 100°C for 4 minutes to obtain a filamentous adhesive with a diameter (width in the short direction) of 160 μm and a porosity of 10%.

[0079] <Example 2> Except for the conditions of the core material used and the tension applied to the core material as shown in Table 1, a filamentous adhesive material with a diameter (width in the short direction) of 450 μm and a porosity of 15% was obtained in the same manner as in Example 1.

[0080] <Example 3> Except for the conditions of the core material used and the tension applied to the core material as shown in Table 1, a filamentous adhesive material with a diameter (width in the short direction) of 200 μm and a void ratio of 5% was obtained in the same manner as in Example 1.

[0081] <Example 4> Except for the conditions of the core material used and the tension applied to the core material as shown in Table 1, a filamentous adhesive material with a diameter (width in the short direction) of 450 μm and a porosity of 14% was obtained in the same manner as in Example 1.

[0082] <Example 5> Except for the conditions of the core material used and the tension applied to the core material as shown in Table 1, a filamentous adhesive material with a diameter (width in the short direction) of 450 μm and a porosity of 14% was obtained in the same manner as in Example 1.

[0083] <Example 6> Except for the conditions of the core material used and the tension applied to the core material as shown in Table 1, a filamentous adhesive material with a diameter (width in the short direction) of 450 μm and a porosity of 19% was obtained in the same manner as in Example 1.

[0084] <Example 7> Except for the conditions of the core material used and the tension applied to the core material as shown in Table 1, a filamentous adhesive material with a diameter (width in the short direction) of 450 μm and a void ratio of 5% was obtained in the same manner as in Example 1.

[0085] <Example 8> Core materials meeting the conditions listed in Table 1 were prepared. This core material was placed on a separator with an adhesive thickness of 40 μm, and the adhesive obtained by drying coating liquid 1 at 100°C for 4 minutes was transferred around the core material while winding it, thereby obtaining a filamentous adhesive with a diameter (width in the shorter direction) of 450 μm and a void ratio of 19%.

[0086] <Example 9> Core materials meeting the conditions listed in Table 1 were prepared. This core material was placed on a separator with an adhesive thickness of 20 μm, and the adhesive obtained by drying coating liquid 1 at 100°C for 4 minutes was transferred around the core material while winding it, thereby obtaining a filamentous adhesive with a diameter (width in the shorter direction) of 450 μm and a void ratio of 47%.

[0087] <Comparative Example 1> Core materials meeting the conditions listed in Table 1 were prepared. The solid content concentration and viscosity of coating solution 1 were set to those shown in Table 1, and the solution was applied to the core material by dipping while spreading the fibers. At that time, the core material was subjected to the tension shown in Table 1. After drying for 5 minutes, a thread-like adhesive material with a diameter (width in the short direction) of 200 μm was obtained.

[0088] <Comparative Example 2> Core materials meeting the conditions listed in Table 1 were prepared. This core material was placed on a separator with an adhesive thickness of 10 μm, and the adhesive obtained by drying coating liquid 1 at 100°C for 4 minutes was transferred around the core material while winding it, thereby obtaining a thread-like adhesive body with a diameter (width in the shorter direction) of 450 μm.

[0089] <Comparative Example 3> (Preparation of coating solution 2) In a reaction vessel equipped with a condenser, nitrogen inlet tube, thermometer, dropping funnel, and stirring device, 69 parts by mass of toluene and 163 parts by mass of ethyl acetate were added as solvents, along with 80 parts by mass of butyl acrylate, 20 parts by mass of 2-ethylhexyl acrylate, 3 parts by mass of acrylic acid, 5 parts by mass of vinyl acetate, 0.1 parts by mass of 2-hydroxyethyl acrylate, and 0.2 parts by mass of 2,2-azobisisobutyronitrile as an initiator. Polymerization was carried out at 60°C for 6 hours under a nitrogen atmosphere to obtain a solution of acrylic polymer.

[0090] To this solution, 30 parts by mass of polymerized rosin ester resin and 1.5 parts by mass (on a solid content basis) of isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L") were added per 100 parts by mass of polymer components in the solution to obtain coating solution 2.

[0091] (Manufacturing of adhesive tape) The coating liquid 2 was applied to a 135 μm thick silicone-treated release paper (release liner A) using an applicator, and dried at 110°C for 3 minutes to obtain a 50 μm thick adhesive layer.

[0092] A black polyethylene foam substrate (manufactured by Sekisui Chemical Co., Ltd., product name "Borara XL-HN#03001W Shorikuro", thickness: 0.10 mm, foaming ratio: 2.9 cc / g) was bonded onto this adhesive layer so that it was in contact with the adhesive layer, thereby obtaining a single-sided adhesive tape T having a layer structure of release liner A / adhesive layer / foam substrate.

[0093] Next, coating liquid 2 was applied onto the release liner B using an applicator and dried at 110°C for 3 minutes to obtain an adhesive layer with a thickness of 50 μm.

[0094] The single-sided adhesive tape T was then bonded onto this adhesive layer so that it was in contact with the foam substrate, and the release liner B was peeled off to obtain a foamed double-sided adhesive tape having a layer structure of release liner A / adhesive layer / foam substrate / adhesive layer.

[0095] (Viscosity of coating solution) The viscosity of the coating solution was measured when the shear rate was changed from high (viscosity decrease) to low (viscosity recovery).

[0096] Specifically, 1 g of sample (coating solution) was placed in a measuring plate (MP35 Steel, 18 / 8, sensor: Rotor C35 / 1, Cone with D=35 mm, 1° Titanium, gap between plates: 0.225 mm), and a viscosity / viscoelasticity measuring device (rheometer, product name "RS-600", manufactured by HAAKE) was used to first measure the solution viscosity (Pa·s) of the coating solution at a shear rate of 0.01 (1 / s) for 10 seconds under conditions of 23°C. Then, the shear rate was changed to 9000 (1 / s) (A) over 20 seconds, and then returned to 0.01 (1 / s) (B) over 20 seconds, and the solution viscosity (Pa·s) of the coating solution was measured during this period.

[0097] When the above shear rate was changed to 9000 (1 / s) (A), the value of the solution viscosity (Pa·s) of the coating liquid when the shear rate was 100 (1 / s) was defined as the solution viscosity (Pa·s) at a shear rate of 100 (1 / s). Also, when the above shear rate was returned to 0.01 (1 / s) (B), the value of the solution viscosity (Pa·s) of the coating liquid when the shear rate was 0.1 (1 / s) was defined as the solution viscosity (Pa·s) at a shear rate of 0.1 (1 / s).

[0098] (Core material tension) The tension of the core material was measured during coating using a digital force gauge (AD-4932A). Specifically, the tension from the core material feed point to the coating roll was measured by reading the stress applied to the terminals of the force gauge.

[0099] (Porosity: Examples 1-9, Comparative Examples 1 and 2) The porosity of the filamentous adhesive was calculated using an X-ray CT scanner (Xradia 520 Versa, Zeiss, tube voltage 60kV, tube current 83μA, pixel size 1.5μm / pixel).

[0100] Specifically, 1601 continuous transmission images were taken of the entire circumference of the filamentous adhesive from 0° to 360°. The obtained images were reconstructed in 3D using image analysis software [ImageJ, AVIZO (Thermo Fisher Scientific)]. The core material, adhesive, and air contained within the filamentous adhesive were identified by trinarization and noise reduction based on luminance. This identification was performed by checking the luminance of air and adhesive separately and setting a first threshold at their midpoint, and then checking the luminance of adhesive and core material separately and setting a second threshold at their midpoint. Using the images obtained by trinarization, the volume ratio of core material, air, and adhesive was calculated to obtain the porosity of the filamentous adhesive. The results are shown in Table 1.

[0101] To calculate the porosity, a 2 cm sample was placed in an X-ray CT scanner, and a section with a length of 2.7 mm in the fiber direction (longitudinal direction) was cut out to calculate the porosity.

[0102] Furthermore, in Examples 1 to 9, it was confirmed using an X-ray CT scanner that the adhesive was covering the core material and that the adhesive was impregnating the core material.

[0103] Furthermore, a cross-sectional photograph of the filamentous adhesive material of Example 2 was obtained using an X-ray CT scanner. This cross-sectional photograph is shown in Figure 1.

[0104] (Porosity: Comparative Example 3) The porosity of the foam substrate was calculated based on the following formula. Expansion ratio = 1 / (1 - porosity)

[0105] The void ratio of the entire foamed double-sided adhesive tape was calculated with an adhesive layer thickness of 50 μm (total adhesive layer thickness: 100 μm) and a foam substrate thickness of 100 μm. The results are shown in Table 1.

[0106] (value of a / b) a: The length of the longest straight line that can be placed in the void, and b: The length of the widest part in the cross-section obtained by cutting the filamentous adhesive perpendicular to the longitudinal direction, were measured using the above-mentioned X-ray CT apparatus.

[0107] Specifically, 1601 continuous transmission images were taken of the entire circumference of the filamentous adhesive material from 0° to 360°. The obtained images were reconstructed in 3D using image analysis software [ImageJ, AVIZO (Thermo Fisher Scientific)]. The core material, adhesive, and air contained within the filamentous adhesive material were identified by trinarization and noise reduction based on their brightness. This identification was performed by checking the brightness of air and adhesive separately and setting a first threshold value based on their midpoint, and then checking the brightness of adhesive and core material separately and setting a second threshold value based on their midpoint. The a / b value was calculated using the images obtained by trinarization. The results are shown in Table 1.

[0108] To calculate the a / b value, a 2cm sample was placed in an X-ray CT scanner, and a 2.7mm length (longitudinal direction) section was cut out to calculate the a / b value.

[0109] (Evaluation of impact resistance) The impact resistance of the filamentous adhesive material or foamed double-sided adhesive tape was evaluated by the following method. First, we prepared the first and second components as shown below. First component: A square acrylic sheet with sides of 70mm and a thickness of 3mm. Second component: A rectangular polycarbonate resin sheet measuring 80mm (short side) x 110mm (long side) and 10mm (thickness) with a rectangular slit (30mm (short side) x 40mm (long side)) in the center.

[0110] Next, a thread-like adhesive or foamed double-sided adhesive tape was attached to the first member along all four sides to form a rectangle measuring 50 x 60 mm. Then, the first member and the second member were joined together so that the center of the first member and the center of the slit in the second member coincided, and the joint was obtained by applying pressure at 0.3 MPa for 20 seconds. A schematic diagram of the joint is shown in Figure 2.

[0111] Then, the joint was dropped onto the steel plate from a height of 5 cm in the order of arrows 21 to 26 in the directions of arrows 21 to 26 in Figure 2. This constituted one set, and if the two components had not separated after three sets (a total of 18 drops), the height was increased. Starting from a height of 5 cm, the height was increased in the order of 15 cm, 30 cm, 60 cm, and 90 cm, and the same operation was performed. The number of drops at which the two components separated is listed in Table 1.

[0112] (Evaluation of reworkability) A square acrylic sheet (70mm per side, 3mm thick) and a 5cm length of thread-like adhesive or foamed double-sided adhesive tape were prepared. The thread-like adhesive or foamed double-sided adhesive tape was attached to the acrylic sheet so that 1cm of it extended beyond the edge of the sheet.

[0113] Subsequently, an acrylic plate of the same shape was placed on top of the thread-like adhesive or foamed double-sided adhesive tape, and the joint was obtained by pressing it at 0.3 MPa for 20 seconds. The protruding thread-like adhesive or foamed double-sided adhesive tape was pulled in a direction perpendicular to the longitudinal direction of the thread-like adhesive or foamed double-sided adhesive tape, and evaluated according to the following evaluation criteria. The results are shown in Table 1.

[0114] ○: The filamentous adhesive or foamed double-sided adhesive tape could be pulled out without damaging the core material or base material. ×: The core material or base material was damaged when pulling out the thread-like adhesive or foamed double-sided adhesive tape, or the thread-like adhesive or foamed double-sided adhesive tape could not be pulled out.

[0115] [Table 1]

[0116] Table 1 shows that when comparing Examples 1 and 3 and Comparative Example 1, which have similar diameters, the filamentous adhesive of Example 1 had higher impact resistance. Similarly, when comparing Examples 2, 4-9 and Comparative Example 2, which all have the same diameter, it was found that the filamentous adhesives of Examples 2, 4-9 had higher impact resistance. Furthermore, Comparative Example 3 was found to have low impact resistance and poor reworkability.

[0117] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2020-165590 filed on 30 September 2020, the contents of which are incorporated herein by reference. [Explanation of Symbols]

[0118] 11 First member 12 Second member 13 Zygote 21 Arrows 22 Arrows 23 Arrows 24 Arrows 25 Arrows 26 Arrows

Claims

1. A method for manufacturing a filamentous adhesive having a core material with multiple filaments and an adhesive, The aforementioned filamentous adhesive contains 1 to 55 volume percent of voids, The process includes applying a coating liquid containing the adhesive to the core material, Excluding the fiber opening process, In the coating process, a tension of 6.0 mN / dtex or less is applied to the core material. A method for manufacturing a filamentous adhesive.

2. In the aforementioned coating process, a roller is used, The method for manufacturing a filamentous adhesive body according to claim 1, wherein the rotation speed of the roller is 0.3 to 5.0 times the feeding speed of the core material.

3. A method for producing a filamentous adhesive according to claim 1 or 2, wherein the viscosity of the coating liquid at a shear rate of 100 (1 / s) is 0.03 to 6 Pa·s, and the viscosity of the coating liquid at a shear rate of 0.1 (1 / s) is 2 to 140 Pa·s.

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