Adhesive sheet for bicycle rims

Abstract

The present invention provides adhesive tape for bicycle rims which has favorable workability. The adhesive tape for bicycle rims is an adhesive sheet to be used for blocking spoke holes in a bicycle rim, said adhesive sheet comprising a support substrate and an adhesive agent layer which is disposed on one surface of the support substrate, wherein at a temperature of 0°C, 10 seconds after affixation to an aluminum plate serving as an adherend, peel strength as measured with a pulling speed of 300 mm / minute and a peeling angle of 180 degrees is not less than 2 N / 20 mm, and at a temperature of 0°C, shear adhesive strength as measured with an aluminum plate serving as an adherend is not less than 200 N / 400mm2.

Description

Technical Field

[0001] The present invention relates to an adhesive sheet used for a rim of a bicycle. This application claims priority based on Japanese Patent Application No. 2021-95920 filed on June 8, 2021, and the entire contents of that application are incorporated herein by reference.

Background Art

[0002] A bicycle wheel typically has a structure including a hub at the center of the wheel, an annular rim supporting the outer peripheral portion of the wheel, and a plurality of spokes connecting the annular rim and the central hub. The spokes basically extend radially from the hub and are connected to the rim, and the rim is provided with through holes for attaching the spokes. Such spoke attachment holes in the rim are generally called spoke holes.

[0003] A tire is mounted on the outer periphery of the annular rim. In such a wheel with a tire, the inside of the tire has a hollow structure. Generally, a rubber tire tube is disposed in the hollow portion of a bicycle tire, and the tire tube is filled and sealed with air to form an inflated tire. On the other hand, so-called tubeless tires in which a tire tube is not disposed in the hollow portion of the tire have also been put into practical use. In the case of a bicycle equipped with a tubeless tire, air is directly filled into the hollow portion of the tire in the wheel with a tire to form an inflated tire. Therefore, high airtightness is required for a wheel with a tubeless tire. Patent Document 1 is cited as a technical document related to these technologies.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] To improve the airtightness of wheels with tubeless tires, a sealing structure is necessary to block the spoke holes in the rim. Furthermore, even in bicycles equipped with tires that use inner tubes (hereinafter referred to as "tube-type tires"), the unevenness around the spoke holes in the rim can be a factor in the damage to the inner tube during riding. Therefore, in both types of bicycles, it is common practice to seal the spoke holes in the rim by wrapping an adhesive sheet, at least wider than the diameter of the spoke holes, around the outer circumference of the rim, including the spoke connection area, before mounting the tire.

[0006] In the process of wrapping adhesive sheets around the outer circumference of a rim, the typical method involves slightly unwinding the rolled adhesive sheet, fixing the tip of the sheet to a specific point (starting point) on the outer circumference of the rim, and then continuing to unwind the sheet while wrapping it around the rim. During this process, if the adhesive force cannot withstand the tension of unwinding the sheet, and the tip of the sheet peels off from the starting point, the workability of wrapping the adhesive sheet is greatly reduced. In particular, the adhesive strength of adhesive sheets tends to decrease in low-temperature environments, so improving the workability of wrapping adhesive sheets around rims in low-temperature environments is an important issue.

[0007] In view of these circumstances, the present invention aims to provide an adhesive tape for bicycle rims that offers good workability. [Means for solving the problem]

[0008] This specification provides an adhesive sheet used to seal spoke holes in a bicycle rim. The adhesive sheet comprises a support substrate and an adhesive layer disposed on one surface of the support substrate. The adhesive sheet has a peel strength of 2 N / 20 mm or more, measured 10 seconds after being attached to an aluminum plate as a substrate at a temperature of 0°C, with a tensile speed of 300 mm / min and a peel angle of 180 degrees. Furthermore, the adhesive sheet has a shear adhesive strength of 200 N / 400 mm, measured with an aluminum plate as the substrate at a temperature of 0°C. 2 That's all.

[0009] Because the adhesive sheet with this configuration exhibits excellent adhesive strength immediately after application to the substrate, it shows good adhesion to the bicycle rim even immediately after the tip of the adhesive sheet is brought into close contact with the starting point on the outer circumference of the rim when wrapping it around the bicycle rim. Furthermore, because the adhesive sheet with the above configuration has excellent shear adhesion, it is particularly easy to withstand the tension and exhibit good adhesion even when wrapping it along a curved bicycle rim while applying unwinding tension. For this reason, the adhesive sheet with the above configuration tends to be easy to work with when wrapping it around a bicycle rim. In particular, the workability tends to improve when the above work is performed in a low-temperature environment.

[0010] In one preferred embodiment of the adhesive sheet disclosed herein, the adhesive layer has a storage modulus of 1.0 × 10⁻⁶ at 0°C. 5 ~1.0×10 6 The storage modulus of the adhesive layer at 0°C is within the above range, which tends to improve adhesion.

[0011] In one preferred embodiment of the adhesive sheet disclosed herein, the adhesive layer is an acrylic adhesive layer containing an acrylic polymer. An adhesive sheet containing such an adhesive layer exhibits good adhesion to metals and resins, and is therefore preferred as an adhesive sheet for bicycle rims.

[0012] In a preferred embodiment of the adhesive sheet disclosed herein, the thickness of the adhesive layer is 30 μm or more and 75 μm or less. When the thickness of the adhesive layer is above the lower limit, it tends to exhibit good adhesive properties. Furthermore, when the thickness of the adhesive layer is below the upper limit, it tends to exhibit excellent shear adhesion.

[0013] In a preferred embodiment of the adhesive sheet disclosed herein, the support substrate is a resin film substrate. An adhesive sheet including such a support substrate tends to have excellent conformability to uneven surfaces, and therefore can effectively seal the spoke holes of the rim.

[0014] In one preferred embodiment of the adhesive sheet disclosed herein, the support substrate includes a polyester film as the base film. An adhesive sheet including such a support substrate is likely to satisfy the requirements for handling, processability, etc., and also satisfy the heat resistance required for an adhesive sheet for bicycle rims.

[0015] In a preferred embodiment of the adhesive sheet disclosed herein, the support substrate further includes a colored layer disposed on the surface of the base film on the side of the adhesive layer. With an adhesive sheet having such a configuration, the support substrate is colored, which tends to provide excellent concealment and aesthetic appeal to the bicycle rim as the adherend. Furthermore, because the colored layer is disposed on the surface of the base film on the side of the adhesive layer, the colored layer is protected by being sandwiched between the base film and the adhesive layer, which helps to suppress the occurrence of events such as the colorant detaching due to friction on the surface of the adhesive sheet or the adhesive sheet fading.

[0016] In a preferred embodiment of the adhesive sheet disclosed herein, the thickness of the support substrate is 60 μm or more and 100 μm or less. When the thickness of the support substrate is greater than or equal to the lower limit, it can withstand the air pressure applied to the adhesive sheet and is more likely to suitably mitigate the unevenness of the adherend. Furthermore, when the thickness of the support substrate is less than or equal to the upper limit, it is preferable from the viewpoint of reducing the weight of the adhesive sheet.

[0017] The adhesive sheet disclosed herein is used, in a preferred embodiment, to seal the spoke holes of a bicycle rim for a tubeless tire. Improving the airtightness of the tire-rim assembly in a wheel with a tubeless tire is an important issue. Therefore, using the adhesive sheet of the present invention to seal the spoke holes of a bicycle rim for a tubeless tire is particularly significant.

[0018] Furthermore, combinations of the above-mentioned elements may also be included within the scope of the invention for which patent protection is sought in this patent application. [Brief explanation of the drawing]

[0019] [Figure 1] This is a plan view showing one example of a wheel configuration with a tubeless tire. [Figure 2] This is a cross-sectional view taken along the line II-II' in Figure 1. [Figure 3] This is a plan view showing one example of a wheel configuration with a tube-type tire. [Figure 4] Cross-sectional view along line IV-IV' in Figure 3. [Figure 5] This is a schematic diagram illustrating the process of wrapping the adhesive sheet around the outer circumference of the rim. [Figure 6] This is a schematic cross-sectional view showing one example of the structure of an adhesive sheet. [Modes for carrying out the invention]

[0020] Preferred embodiments of the present invention are described below. Matters other than those specifically mentioned herein but necessary for carrying out the present invention can be understood by those skilled in the art based on the teachings on carrying out the invention described herein and the common technical knowledge at the time of filing. The present invention can be carried out based on the contents disclosed herein and the common technical knowledge in the art. Furthermore, in the following drawings, components and parts that perform the same function may be denoted by the same reference numerals and described accordingly, and redundant descriptions may be omitted or simplified. Also, the embodiments shown in the drawings are schematic for the purpose of clearly illustrating the present invention and do not necessarily accurately represent the size or scale of the actual product provided.

[0021] The adhesive sheets disclosed herein are used to seal the spoke holes of a bicycle rim. The configuration and structure of the bicycle rim on which the adhesive sheets are used are not particularly limited. A typical configuration of a wheel with a tire, including a bicycle rim, is briefly described below with reference to Figures 1 to 4, but these are merely examples and do not limit the manner of use, target, and purpose of use of the adhesive sheets disclosed herein.

[0022] Figure 1 shows an example configuration of a wheel 10 with a tubeless tire. The wheel 12 consists of a central hub 14, an annular rim 16 that supports the outer circumference of the wheel 12, and a plurality of spokes 18 that extend outward from the central hub 14 and are connected to the annular rim 16. The spokes 18 are connected to the rim 16 at circumferential positions at regular intervals. A tire 20 is fixedly mounted on the outside of the annular rim 16 (i.e., the outside as viewed from the center of the wheel, the same applies hereafter).

[0023] Figure 2 is a cross-sectional view taken along the line II-II' in Figure 1. The rim 16 comprises a pair of opposing side portions 22, a U-shaped portion 24 whose ends are connected to the other side portions 22, and a connecting portion 26 extending in the wheel rotation axis direction (hereinafter also simply referred to as "axial direction") between the two side portions 22. Both ends of the connecting portion 26 are connected to the other side portions 22, and together with the U-shaped portion 24, form region A. In addition, hook portions 28 for connecting the tire 20 are provided at the ends of the side portions 22. A spoke housing opening 30 for accommodating spokes 18 is provided in the axial central region of the U-shaped portion 24. In addition, a spoke connecting opening (spoke hole) 32 for connecting to the spokes 18 is provided in the axial central region of the connecting portion 26. The positions and number of spoke holes 32 and spoke housing openings 30 are provided to correspond to the arrangement positions and number of spokes 18, respectively, and specifically, multiple such openings are provided in the circumferential direction at regular intervals on the rim 16.

[0024] Each spoke 18 comprises a wire-like shaft portion 34 and a head portion 36 provided at the outer end of the shaft portion. The shaft portion 34 is positioned to pass through the spoke housing opening 30 and the spoke hole 32, and the head portion 36 of the spoke 18 is provided outside the connecting portion 26 of the rim 16. The method of connecting the spoke 18 and the rim 16 is not particularly limited and can be done by conventional methods.

[0025] The adhesive sheet 40 is positioned so as to wrap around the entire outer circumference of the connection portion 26 of the rim 16 with a width such that at least the spoke holes 32 and the heads 36 of the spokes 18 are completely covered. With the adhesive sheet 40 positioned in this way, the spoke connection area of ​​the rim 16, including the spoke holes 32, is sealed.

[0026] The tire 20 comprises an annular tire portion 42 positioned on the outside and a bead portion 44 at the end of the annular tire portion 42 that joins with the rim 16. The bead portion 44 of the tire 20 engages with the hook portion 28 of the rim 16. The annular tire portion 42 of the tire 20, together with the side portion 22 and connecting portion 26 of the rim 16, forms a hollow region B. Since the tire 20 shown in Figure 2 is a tubeless tire, the hollow region B is filled with air. In this embodiment, since the spoke holes 32 of the rim 16 are suitably sealed by the adhesive sheet 40, the hollow region B is a region with excellent airtightness.

[0027] Figure 3 shows one embodiment of a wheel 50 with a tubed tire. The basic configuration of the wheel 50 with a tire shown in Figure 3 is the same as the basic configuration of the tubeless wheel 10 shown in Figure 1, so no explanation is given. Figure 4 is a cross-sectional view taken along the line IV-IV' in Figure 3. The configuration of the rim 16, spokes 18, and tire 20 shown in Figure 4 is the same as the configuration of each component shown in Figure 2. An annular hollow tube 46 is placed in the region formed by the annular tire portion 42 of the tire 20 and the side portion 22 and connecting portion 26 of the rim 16 shown in Figure 4, and the inside of the hollow structure of the tube 46 is filled with air. In this embodiment, the spoke holes 32 of the rim 16 are suitably sealed by the adhesive sheet 40, so steps caused by the spoke holes 32 and the heads 36 of the spokes 18 tend to be mitigated by the adhesive sheet 40. With a wheel 50 with a tire configured in this way, damage to the tire tube 46 during bicycle riding is easily suppressed.

[0028] Next, with reference to Figure 5, an example of the process of wrapping the adhesive sheet 40 disclosed herein around the rim 16 will be described. In the process of wrapping the adhesive sheet 40 around the rim 16, the adhesive sheet 40 is typically used in the form of a roll wound into a spiral. The roll of adhesive sheet 40 is unwound slightly to pull out the leading edge of the adhesive sheet 40, and the adhesive surface of the leading edge is brought into close contact with a certain area (starting point) on the outer circumference of the rim connection portion 26. If necessary, the leading edge that is in contact with the starting point of the rim 16 is then subjected to appropriate pressure from the worker's fingers on top of the adhesive sheet 40. Subsequently, the adhesive sheet 40 is further unwound and wrapped around the outer circumference of the rim connection portion 26, securing it in place. During the process, in order to uniformly adhere the adhesive sheet 40 along the curved outer circumference of the rim without causing wrinkles, the adhesive sheet 40 is wrapped with a constant tension in the direction of arrow C shown in Figure 5. The number of times the adhesive sheet 40 is wrapped around the outer circumference of the rim 16 is not particularly limited, but typically it is wrapped around the outer circumference of the rim 16 about 1 to 2 times.

[0029] (Peel strength immediately after application) The adhesive sheet disclosed herein exhibits excellent adhesive strength immediately after application to the substrate. With such an adhesive sheet, when the leading edge of the adhesive sheet is brought into close contact with the starting point of the rim during the wrapping process, the leading edge of the adhesive sheet can be suitably fixed to the rim, improving the workability of the wrapping process. The adhesive sheet disclosed herein exhibits particularly excellent adhesive strength immediately after application to the substrate in low-temperature environments. With such an adhesive sheet, even when wrapping work on a rim in a low-temperature environment (for example, in an outdoor environment during winter), workability is easily improved.

[0030] The adhesive sheet disclosed herein has a peel strength (hereinafter also referred to as low-temperature immediate peel strength S0) of 2N / 20mm or more, measured 10 seconds after being attached to an aluminum plate as an adherend at a temperature of 0°C, under conditions of a tensile speed of 300 mm / min and a peel angle of 180 degrees. An adhesive sheet exhibiting such a low-temperature immediate peel strength S0 makes it easier to improve the workability of wrapping work around rims (for example, wrapping work around rims in a low-temperature environment). From the viewpoint of further improving workability, a low-temperature immediate peel strength S0 of 3N / 20mm or more is more preferable, even more preferable is 4N / 20mm or more, and particularly preferable is 4.5N / 20mm or more. The upper limit of the low-temperature immediate peel strength S0 is not particularly limited, but from the viewpoint of balancing with other adhesive properties, it may be 10N / 20mm or less, 8N / 20mm or less, or 7N / 20mm or less. The low-temperature immediate peel strength S0 is specifically measured by the method shown in the examples described later.

[0031] (Shear adhesion) Furthermore, the adhesive sheet disclosed herein has excellent shear adhesion. With such an adhesive sheet, even when the adhesive sheet is applied to the rim while being pulled in the direction of the sheet surface to ensure close contact with the rim, it can withstand tensile forces (i.e., shear forces) and is less likely to peel off, thus improving the workability of the wrapping process. The adhesive sheet disclosed herein has particularly excellent shear adhesion in low-temperature environments. With such an adhesive sheet, even when wrapping the rim in low-temperature environments (for example, in the outdoor environment during winter), workability is easily improved.

[0032] The adhesive sheet disclosed herein has a shear adhesion strength (hereinafter also referred to as low-temperature shear adhesion strength P0) of 200 N / 400 mm when the adherend is an aluminum plate under a temperature condition of 0°C. 2The above is the case. According to the adhesive sheet showing such a low-temperature shear adhesion P0, the workability of the winding operation on the rim (for example, the winding operation on the rim in a low-temperature environment) is likely to be improved. From the perspective of further improving workability, the low-temperature shear adhesion P0 is 210 N / 400 mm 2 or more, more preferably 220 N / 400 mm 2 or more, and may be 250 N / 400 mm 2 or more. The upper limit of the low-temperature shear adhesion P0 is not particularly limited, but from the perspective of balancing with other adhesive properties, it may be 400 N / 400 mm 2 or less, may be 350 N / 400 mm 2 or less, and may also be 300 N / 400 mm 2 or less. The low-temperature shear adhesion P0 is specifically measured by the method shown in the examples described later. <00002[03> (Configuration of the Adhesive Sheet) FIG. 6 is a diagram showing a configuration example in a preferred embodiment of the adhesive sheet disclosed herein. The adhesive sheet 40 is configured as a single-sided adhesive adhesive sheet 40 with a base material, including a sheet-like support base material (for example, a resin film) 60 having a first surface 62A and a second surface 62B, and an adhesive layer 64 fixedly provided on the first surface 62A side. The adhesive layer 64 includes an adhesive surface 66 that constitutes one surface of the adhesive sheet 40. Before use, the adhesive sheet 40 can be a component of the adhesive sheet with a release liner 70 in a form protected by a release liner 68 whose adhesive surface 66 of the adhesive layer 64 has at least the side facing the adhesive layer 64 as a release surface. As shown in FIG, 6, the adhesive sheet with a release liner 70 may be configured as a roll-shaped adhesive sheet with a release liner. In the example shown in FIG. 6, the adhesive sheet with a release liner 70 is configured by winding in a spiral shape with the release liner 68 side facing outward, but the winding direction is not limited. The roll-shaped adhesive sheet with a release liner may be configured by winding the adhesive sheet with a release liner with the release liner 68 side facing inward.<00[0206>

[0034] The concept of adhesive sheets as used herein may include adhesive tapes, adhesive films, adhesive labels, etc. Adhesive sheets may be in roll form or sheet form, and may be cut, punched, or otherwise processed into appropriate shapes depending on the application and manner of use. In an adhesive sheet in which an adhesive layer is laminated on one side of a support substrate, the adhesive layer is typically formed continuously, but is not limited to this, and may be formed in regular or random patterns such as dots or stripes.

[0035] (Base polymer) The adhesive sheet disclosed herein includes an adhesive layer. In the technology disclosed herein, the type of adhesive constituting the adhesive layer is not particularly limited. The adhesive may contain one or more of the following rubber-like polymers known in the field of adhesives, such as acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, and fluorine polymers, as a base polymer. From the viewpoint of adhesive performance and cost, an adhesive containing an acrylic polymer or a rubber polymer as a base polymer is preferably used. Among these, an adhesive using an acrylic polymer as a base polymer (acrylic adhesive) is preferred. The following description will mainly focus on an adhesive layer composed of an acrylic adhesive, i.e., an adhesive sheet having an acrylic adhesive layer, but it is not intended to limit the adhesive layer of the adhesive sheet disclosed herein to one composed of an acrylic adhesive.

[0036] Furthermore, the "base polymer" of an adhesive refers to the main component of the rubbery polymer contained in the adhesive. The rubbery polymer refers to a polymer that exhibits rubber elasticity in the temperature range around room temperature. In addition, in this specification, unless otherwise specified, "main component" refers to a component that is present in an amount exceeding 50% by weight. Furthermore, "acrylic polymer" refers to a polymer that contains monomer units derived from monomers having at least one (meth)acryloyl group in one molecule as monomer units constituting the polymer. Hereinafter, monomers having at least one (meth)acryloyl group in one molecule will also be referred to as "acrylic monomers." Therefore, in this specification, acrylic polymers are defined as polymers that contain monomer units derived from acrylic monomers. A typical example of an acrylic polymer is an acrylic polymer in which the proportion of acrylic monomers among all monomer components used in the synthesis of the acrylic polymer is greater than 50% by weight. Furthermore, "(meth)acryloyl" comprehensively refers to both acryloyl and methacryloyl. Similarly, "(meth)acrylate" comprehensively refers to both acrylate and methacrylate, and "(meth)acrylic" comprehensively refers to both acrylic and methacrylic.

[0037] As the above-mentioned acrylic polymer, for example, a polymer of a monomer raw material that contains alkyl (meth)acrylate as the main monomer and may further contain a secondary monomer copolymerizable with the main monomer is preferred. Here, the main monomer refers to a component that accounts for more than 50% by weight of the monomer composition in the above-mentioned monomer raw material.

[0038] As the alkyl (meth)acrylate, for example, a compound represented by the following formula (1) can be suitably used. CH2=C(R 1 )COOR 2 (1) Here, in equation (1) above, R 1 R is a hydrogen atom or a methyl group. 2 C is a chain-like alkyl group with 1 to 20 carbon atoms. Hereafter, this range of carbon atoms will be referred to as "C 1-20 It is sometimes expressed as ". From the viewpoint of the storage modulus of the adhesive, R 2 C 1-14 (For example C 2-10 Typically C 4-8It is appropriate to use alkyl(meth)acrylate, which is a chain-like alkyl group, as the main monomer. From the viewpoint of adhesive properties, 1 is a hydrogen atom and R 2 C 4-8 Alkyl acrylates (hereinafter simply referred to as C) are chain-like alkyl groups. 4-8 It is preferable to use alkyl acrylate (also known as alkyl acrylate) as the main monomer.

[0039] R 2 C 1-20 Examples of alkyl(meth)acrylates, which are chain-like alkyl groups, include methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, isopropyl(meth)acrylate, n-butyl(meth)acrylate, isobutyl(meth)acrylate, s-butyl(meth)acrylate, pentyl(meth)acrylate, isopentyl(meth)acrylate, hexyl(meth)acrylate, heptyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, octyl(meth)acrylate, isooctyl(meth)acrylate. Examples include alkyl(meth)acrylate, nonyl(meth)acrylate, isononyl(meth)acrylate, decyl(meth)acrylate, isodecyl(meth)acrylate, undecyl(meth)acrylate, lauryl(meth)acrylate, tridecyl(meth)acrylate, tetradecyl(meth)acrylate, pentadecyl(meth)acrylate, hexadecyl(meth)acrylate, heptadecyl(meth)acrylate, octadecyl(meth)acrylate, nonadecyl(meth)acrylate, eicosyl(meth)acrylate, etc. These alkyl(meth)acrylates can be used individually or in combination of two or more. Preferred alkyl(meth)acrylates include n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA).

[0040] The proportion of alkyl (meth)acrylate in the monomer components constituting the acrylic polymer is not particularly limited. The proportion of alkyl (meth)acrylate in the monomer components can be approximately 80% by weight or more (typically 80-99.8% by weight), and preferably 85% by weight or more (for example, 85-99.5% by weight). The proportion of alkyl (meth)acrylate in the monomer components may also be 90% by weight or more (for example, 90-99% by weight).

[0041] The technology disclosed herein relates to a monomer component C 1-4 This can preferably be carried out in an embodiment containing 50% by weight or more of alkyl (meth)acrylate. 1-4 The proportion of alkyl (meth)acrylate may be 70% by weight or more, or 85% by weight or more (for example, 90% by weight or more). On the other hand, from the viewpoint of cohesive force, etc., the proportion of C in the monomer component 1-4 The proportion of alkyl (meth)acrylate is usually appropriate to be 99.5% by weight or less, but it may also be 98% by weight or less (for example, less than 97% by weight).

[0042] The technology disclosed herein relates to a monomer component C 2-4 This can preferably be carried out in an embodiment containing 50% by weight or more (for example, 70% by weight or more, or 85% by weight or more, or 90% by weight or more) of alkyl acrylate. 2-4 Specific examples of alkyl acrylates include ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate (BA), isobutyl acrylate, s-butyl acrylate, and t-butyl acrylate. 2-4 Alkyl acrylates can be used individually or in combination of two or more. Such embodiments make it easier to achieve adhesive sheets with good adhesion to the substrate. A particularly preferred embodiment is one in which the monomer component contains more than 50% by weight of BA (for example, 70% or more by weight, or 85% or more by weight, or 90% or more by weight). From the viewpoint of obtaining good cohesive force, etc., the amount of C in the monomer component is important. 1-4The proportion of alkyl (meth)acrylate is usually appropriate to be 99.5% by weight or less, but it may also be 98% by weight or less (for example, less than 97% by weight).

[0043] In another embodiment, the monomer component is C 5-20 The method can also be carried out in an embodiment containing 50% by weight or more of alkyl (meth)acrylate (for example, 70% by weight or more, or 85% by weight or more, or 90% by weight or more). 5-20 As for alkyl (meth)acrylates, C 6-14 Alkyl (meth)acrylates are preferred. In one embodiment, C 6-10 Alkyl acrylate (e.g., C 8-10 Alkyl acrylates may be preferably used.

[0044] As monomer components constituting the acrylic polymer, within the range in which alkyl (meth)acrylate is the main component, other monomers copolymerizable with alkyl (meth)acrylate (sometimes referred to as "copolymerizable monomer components") may also be used.

[0045] The copolymerizable monomer components described above can be useful for introducing crosslinking points into acrylic polymers or for enhancing the cohesive strength of acrylic polymers. Such copolymerizable monomers can be used alone or in combination of two or more.

[0046] More specifically, various functional group-containing monomer components (typically, thermo-crosslinkable functional group-containing monomer components for introducing crosslinking sites into acrylic polymers) can be used as copolymerizable monomer components for introducing crosslinking sites into acrylic polymers by heat. By using such functional group-containing monomer components, the adhesion strength to the adherend can be improved. Such functional group-containing monomer components are not particularly limited, as long as they are copolymerizable with alkyl (meth)acrylates and can provide functional groups that serve as crosslinking sites. For example, functional group-containing monomer components such as carboxyl group-containing monomers, hydroxyl group-containing monomers, amide group-containing monomers, amino group-containing monomers, monomers having epoxy groups, cyano group-containing monomers, keto group-containing monomers, monomers having nitrogen atom-containing rings, and alkoxysilyl group-containing monomers can be used alone or in combination of two or more.

[0047] Examples of carboxyl group-containing monomers include ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; ethylenically unsaturated dicarboxylic acids such as maleic acid, itaconic acid, and citraconic acid, and their anhydrides (maleic anhydride, eicotanic anhydride, etc.). Examples of hydroxyl group-containing monomers include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; and unsaturated alcohols such as vinyl alcohol and allyl alcohol.

[0048] Examples of monomers containing an amide group include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylolpropane(meth)acrylamide, N-methoxymethyl(meth)acrylamide, and N-butoxymethyl(meth)acrylamide. Examples of amino group-containing monomers include aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate.

[0049] Examples of monomers having an epoxy group include glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, and allyl glycidyl ether. Examples of cyano group-containing monomers include acrylonitrile and methacrylonitrile. Examples of keto group-containing monomers include diacetone(meth)acrylamide, diacetone(meth)acrylate, vinyl methyl ketone, vinyl ethyl ketone, allyl acetacetate, and vinyl acetacetate.

[0050] Examples of monomers having a nitrogen atom-containing ring include N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, and N-(meth)acryloylmorpholine.

[0051] Examples of monomers containing an alkoxysilyl group include 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane.

[0052] Among such functional group-containing monomer components, one or more selected from carboxyl group-containing monomers or their acid anhydrides can preferably be used. Substantially all of the functional group-containing monomer components may be carboxyl group-containing monomers. Among these, acrylic acid and methacrylic acid are examples of preferred carboxyl group-containing monomers. One of these may be used alone, or acrylic acid and methacrylic acid may be used in any proportion.

[0053] The above-mentioned functional group-containing monomer component is preferably used in an amount of approximately 10 parts by weight or less (for example, approximately 0.1 to 10 parts by weight, preferably approximately 1.5 to 3.5 parts by weight) per 100 parts by weight of alkyl (meth)acrylate. If too much of the functional group-containing monomer component is used, the cohesive force may become too high, which may lead to a decrease in adhesive properties (e.g., adhesive strength).

[0054] The monomer components constituting the acrylic polymer may include other copolymer components other than the functional group-containing monomers mentioned above, for purposes such as improving cohesiveness. Examples of other copolymer components include vinyl ester monomers such as vinyl acetate, vinyl propionate, and vinyl laurate; aromatic vinyl compounds such as styrene, substituted styrene (e.g., α-methylstyrene), and vinyltoluene; cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, and isobornyl (meth)acrylate; and aromatic ring-containing (meth)acrylates such as aryl (meth)acrylate (e.g., phenyl (meth)acrylate), aryloxyalkyl (meth)acrylate (e.g., phenoxyethyl (meth)acrylate), and arylalkyl (meth)acrylate (e.g., benzyl (meth)acrylate). Examples include: olefin monomers such as ethylene, propylene, isoprene, butadiene, and isobutylene; chlorine-containing monomers such as vinyl chloride and vinylidene chloride; isocyanate group-containing monomers such as 2-(meth)acryloyloxyethyl isocyanate; alkoxy group-containing monomers such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether; and polyfunctional monomers having two or more (e.g., three or more) polymerizable functional groups (e.g., (meth)acryloyl groups) in one molecule, such as 1,6-hexanediol di(meth)acrylate and trimethylolpropane tri(meth)acrylate.

[0055] The amount of such other copolymer components is not particularly limited and can be appropriately selected according to the purpose and application. From the viewpoint of appropriately exhibiting the effects of use, it is usually appropriate to have 0.05% by weight or more, and may be 0.5% by weight or more. Furthermore, from the viewpoint of easily balancing the adhesive performance, it is usually appropriate to have the content of other copolymer components in the monomer component at 20% by weight or less, and may be 10% by weight or less (for example, 5% by weight or less). The technology disclosed herein can also be preferably implemented in a form in which the monomer component substantially does not contain other copolymer components. Here, "substantially free of other copolymer components" means that other copolymer components are not used at least intentionally, and it is permissible for other copolymer components to be unintentionally included in amounts of, for example, 0.01% by weight or less.

[0056] The copolymerization composition of acrylic polymers is appropriately designed so that the glass transition temperature (Tg) of the polymer is approximately -15°C or lower (for example, approximately -70°C to -15°C). Here, the Tg of the acrylic polymer refers to the Tg determined by Fox's formula based on the composition of the monomer components used in the synthesis of the polymer. Fox's formula is a relationship between the Tg of a copolymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer, as shown below. 1 / Tg = Σ(Wi / Tgi) In Fox's equation above, Tg represents the glass transition temperature of the copolymer (unit: K), Wi represents the weight fraction of monomer i in the copolymer (weight-based copolymerization ratio), and Tgi represents the glass transition temperature of the monomer i homopolymer (unit: K).

[0057] The glass transition temperature of the homopolymer used in calculating Tg shall be the value specified in publicly available documents. For example, for the monomers listed below, the following values ​​shall be used as the glass transition temperature of the homopolymer of the monomer. 2-Ethylhexyl acrylate -70℃ Isononyl acrylate -60℃ n-butyl acrylate -55℃ Ethyl acrylate -22℃ Methyl acrylate 8℃ Methyl methacrylate 105℃ 2-Hydroxyethyl acrylate -15℃ 4-Hydroxybutyl acrylate -40℃ Vinyl acetate 32℃ Acrylic acid 106℃ Methacrylic acid 228℃

[0058] For the glass transition temperatures of monomer homopolymers other than those exemplified above, the values ​​listed in the "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) shall be used. For monomers for which multiple values ​​are listed in this document, the highest value shall be adopted. If the value is not listed in the Polymer Handbook, the value obtained by the measurement method described in Japanese Patent Application Publication No. 2007-51271 shall be used.

[0059] While not particularly limited, from the viewpoint of adhesion to the adherend, the Tg of the acrylic polymer is advantageous to be approximately -25°C or lower, preferably approximately -35°C or lower, and more preferably approximately -40°C or lower. In one embodiment, from the viewpoint of cohesive force, the Tg of the acrylic polymer may be, for example, approximately -70°C or higher, approximately -65°C or higher, or approximately -60°C or higher. The techniques disclosed herein can preferably be carried out in an embodiment in which the Tg of the acrylic polymer is approximately -70°C or higher and -35°C or lower (for example, approximately -60°C or higher and -40°C or lower). The Tg of the acrylic polymer can be adjusted by appropriately changing the monomer composition (i.e., the type and ratio of monomers used in the synthesis of the polymer).

[0060] The method for obtaining acrylic polymers is not particularly limited, and various polymerization methods known as synthesis methods for acrylic polymers, such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and photopolymerization, can be appropriately employed. For example, solution polymerization can be preferably employed. The polymerization temperature when performing solution polymerization can be appropriately selected depending on the type of monomer and solvent used, the type of polymerization initiator, etc., and can be, for example, around 20°C to 170°C (typically around 40°C to 140°C).

[0061] The solvent used for solution polymerization (polymerization solvent) can be appropriately selected from conventionally known organic solvents. For example, one solvent or a mixture of two or more solvents can be used, selected from aromatic compounds such as toluene (typically aromatic hydrocarbons); acetic acid esters such as ethyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; halogenated alkanes such as 1,2-dichloroethane; lower alcohols such as isopropyl alcohol (e.g., monohydric alcohols with 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether; ketones such as methyl ethyl ketone; etc.

[0062] The initiator used for polymerization can be appropriately selected from conventionally known polymerization initiators depending on the type of polymerization method. For example, one or more azo polymerization initiators such as 2,2'-azobisisobutyronitrile (AIBN) can be preferably used. Other examples of polymerization initiators include persulfates such as potassium persulfate; peroxide initiators such as benzoyl peroxide and hydrogen peroxide; substituted ethane initiators such as phenyl-substituted ethane; aromatic carbonyl compounds; and so on. Another example of polymerization initiators is a redox initiator, which is a combination of a peroxide and a reducing agent. Such polymerization initiators can be used individually or in combination of two or more. The amount of polymerization initiator used can be the usual amount, for example, it can be selected from a range of approximately 0.005 to 1 part by weight (typically about 0.01 to 1 part by weight) per 100 parts by weight of monomer component.

[0063] The above solution polymerization yields a polymerization reaction solution in which the acrylic polymer is dissolved in an organic solvent. The adhesive layer in the art disclosed herein may be formed from an adhesive composition containing the above polymerization reaction solution or an acrylic polymer solution obtained by subjecting the reaction solution to appropriate post-treatment. As the acrylic polymer solution, the above polymerization reaction solution may be used after being adjusted to an appropriate viscosity (concentration) as needed. Alternatively, an acrylic polymer solution may be prepared by synthesizing an acrylic polymer by a polymerization method other than solution polymerization (e.g., emulsion polymerization, photopolymerization, bulk polymerization, etc.) and dissolving the acrylic polymer in an organic solvent.

[0064] The weight-average molecular weight (Mw) of the base polymer (preferably an acrylic polymer) in the technologies disclosed herein is not particularly limited, for example, approximately 5 × 10 4 ~500×10 4 It can be within this range. From the standpoint of adhesive performance, the Mw of the base polymer is approximately 10 × 10 4 ~200×10 4 (more preferably approximately 20 × 10 4 ~150×10 4 Typically, approximately 30 x 10 4 ~100×10 4 It is preferable that the Mw is within the range of ). By using a base polymer with a high Mw, it is easier to obtain better impact resistance by utilizing the cohesive force of the polymer itself. Here, Mw refers to the value obtained by GPC (gel permeation chromatography) on a standard polystyrene basis. As a GPC device, for example, the model name "HLC-8120GPC" (column: TSKgel SuperHM-H / H4000 / H3000 / H2000, manufactured by Tosoh Corporation) can be used. The same measurement method will be used in the examples described later.

[0065] The storage modulus of the base polymer (preferably an acrylic polymer) in the technologies disclosed herein is not particularly limited. In one preferred embodiment, the storage modulus of the base polymer at 0°C is 1.0 × 10⁻⁶ 4 Pa or higher, more preferably 5.0 × 10 4Pa or higher, more preferably 1.0 × 10 5 Pa or higher, particularly preferably 1.2 × 10⁻⁶ 5 The storage modulus of the base polymer at 0°C is not particularly limited, but is preferably 1.5 × 10⁻⁶. 6 It is less than or equal to Pa, and more preferably 1.0 × 10⁻⁶ 6 Pa or less, more preferably 8.0 × 10 5 Pa or less, particularly preferably 7.5 × 10 5 It is below Pa. When the storage modulus of the base polymer at 0°C is within the above range, the tackiness of the adhesive layer tends to improve.

[0066] In the technology disclosed herein, the 0°C storage modulus of the base polymer can be determined by dynamic viscoelasticity measurement. Specifically, it can be measured in the same manner as the 0°C storage modulus of the adhesive layer described later.

[0067] (Adhesive-forming resin) The adhesive layer in the technology disclosed herein may contain a tackifying resin. This can increase the peel strength of the adhesive sheet. As the tackifying resin, one or more types selected from various known tackifying resins can be used, such as phenolic tackifying resins, terpene tackifying resins, modified terpene tackifying resins, rosin tackifying resins, hydrocarbon tackifying resins, epoxy tackifying resins, polyamide tackifying resins, elastomer tackifying resins, and ketone tackifying resins.

[0068] Examples of phenolic tackifying resins include terpene phenol resins, hydrogenated terpene phenol resins, alkyl phenol resins, and rosin phenol resins. Terpene phenol resins refer to polymers containing terpene and phenol residues, and the concept encompasses both copolymers of terpenes and phenol compounds (terpene-phenol copolymer resins) and homopolymers or copolymers of terpenes modified with phenol (phenol-modified terpene resins). Suitable examples of terpenes constituting such terpene phenol resins include monoterpenes such as α-pinene, β-pinene, and limonene (including d-isomers, l-isomers, and d / l-isomers (dipentene)). Hydrogenated terpene phenol resins refer to hydrogenated terpene phenol resins having a structure obtained by hydrogenating such terpene phenol resins. They are sometimes also called hydrogenated terpene phenol resins. Alkylphenol resins are resins (oil-based phenolic resins) obtained from alkylphenols and formaldehyde. Examples of alkylphenol resins include novolac and resol types. Rosinphenol resins are typically phenol-modified products of rosins or the various rosin derivatives mentioned above (including rosin esters, unsaturated fatty acid-modified rosins, and unsaturated fatty acid-modified rosin esters). Examples of rosinphenol resins include those obtained by methods such as adding phenol to rosins or the various rosin derivatives mentioned above using an acid catalyst and then thermal polymerization.

[0069] Examples of terpene-based tackifying resins include polymers of terpenes (typically monoterpenes) such as α-pinene, β-pinene, d-limonene, l-limonene, and dipentene. These may be homopolymers of a single terpene or copolymers of two or more terpenes. Examples of homopolymers of a single terpene include α-pinene polymers, β-pinene polymers, and dipentene polymers. Examples of modified terpene resins include those obtained by modifying the above-mentioned terpene resins. Specifically, examples include styrene-modified terpene resins and hydrogenated terpene resins.

[0070] The concept of rosin-based tackifying resins as used here encompasses both rosins and rosin derivative resins. Examples of rosins include unmodified rosins (raw rosins) such as gum rosin, wood rosin, and tall oil rosin; and modified rosins (hydrogenated rosin, disproportionated rosin, polymerized rosin, and other chemically modified rosins) obtained by hydrogenation, disproportionation, polymerization, etc.

[0071] Rosin derivative resins are typically derivatives of the rosins described above. The concept of rosin-based resins as used here includes derivatives of unmodified rosin and derivatives of modified rosin (including hydrogenated rosin, disproportionated rosin, and polymerized rosin). Examples include rosin esters such as unmodified rosin esters, which are esters of unmodified rosin with alcohols, and modified rosin esters, which are esters of modified rosin with alcohols; unsaturated fatty acid modified rosins, which are rosins modified with unsaturated fatty acids; unsaturated fatty acid modified rosin esters, which are rosin esters modified with unsaturated fatty acids; rosin alcohols, which are rosins or the above-mentioned rosin derivatives (including rosin esters, unsaturated fatty acid modified rosins, and unsaturated fatty acid modified rosin esters) obtained by reducing their carboxyl groups; and metal salts of rosins or the above-mentioned rosin derivatives. Specific examples of rosin esters include methyl esters, triethylene glycol esters, glycerol esters, and pentaerythritol esters of unmodified rosin or modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.).

[0072] Examples of hydrocarbon-based tackifying resins include aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aliphatic-aromatic petroleum resins (such as styrene-olefin copolymers), aliphatic-alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone resins, and coumarone-indene resins, among other hydrocarbon resins.

[0073] The softening point of the tackifying resin is not particularly limited. From the viewpoint of improving cohesive force, in one embodiment, a tackifying resin having a softening point (softening temperature) of approximately 80°C or higher (preferably approximately 100°C or higher) may be preferably used. The technology disclosed herein can preferably be implemented in a manner in which, with a total amount of tackifying resin contained in the adhesive layer being 100% by weight, more than 50% by weight (more preferably more than 70% by weight, for example more than 90% by weight) of the tackifying resin having the above-mentioned softening point. There is no particular upper limit to the softening point of the tackifying resin. From the viewpoint of improving adhesion to the adherend, in one embodiment, a tackifying resin having a softening point of approximately 200°C or lower (more preferably approximately 180°C or lower) may be preferably used. The softening point of the tackifying resin can be measured based on the softening point test method (ring-ball method) specified in JIS K2207.

[0074] When the adhesive layer contains a tackifying resin, the amount of the tackifying resin used is not particularly limited and can be appropriately set in the range of 1 to 100 parts by weight per 100 parts by weight of the base polymer. From the viewpoint of suitably exhibiting the effect of improving peel strength, the amount of tackifying resin used per 100 parts by weight of the base polymer (e.g., acrylic polymer) is usually appropriate to be 1 part by weight or more, and preferably 3 parts by weight or more. There is no particular upper limit to the amount of tackifying resin used. From the viewpoint of heat-resistant cohesive force, the amount of tackifying resin used per 100 parts by weight of the base polymer (e.g., acrylic polymer) is usually appropriate to be 50 parts by weight or less, and may be 40 parts by weight or less, or 30 parts by weight or less.

[0075] (Crosslinking agent) In the technology disclosed herein, the adhesive composition used to form the adhesive layer may optionally contain a crosslinking agent. The type of crosslinking agent is not particularly limited and can be appropriately selected from conventionally known crosslinking agents. Examples of such crosslinking agents include isocyanate crosslinking agents, epoxy crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, melamine crosslinking agents, peroxide crosslinking agents, urea crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents, carbodiimide crosslinking agents, hydrazine crosslinking agents, amine crosslinking agents, silane coupling agents, and the like. The crosslinking agent can be used alone or in combination of two or more types.

[0076] The total amount of crosslinking agent used is not particularly limited. For example, it can be approximately 10 parts by weight or less per 100 parts by weight of the base polymer (preferably an acrylic polymer), preferably in the range of approximately 0.005 to 10 parts by weight, and more preferably in the range of approximately 0.01 to 5 parts by weight.

[0077] (Other additives) The above adhesive composition may optionally contain various additives common in the field of adhesive compositions, such as leveling agents, crosslinking aids, rust inhibitors, plasticizers, softeners, antistatic agents, anti-aging agents, ultraviolet absorbers, antioxidants, and light stabilizers. Such additives can be conventionally used by ordinary methods and do not particularly characterize the present invention, so a detailed explanation is omitted.

[0078] The adhesive layer (layer consisting of adhesive) disclosed herein may be an adhesive layer formed from an aqueous adhesive composition, a solvent-type adhesive composition, a hot-melt adhesive composition, or an active energy ray-curable adhesive composition. An aqueous adhesive composition refers to an adhesive composition in which an adhesive (adhesive layer forming component) is contained in a solvent (aqueous solvent) mainly composed of water, and typically includes what is called a water-dispersible adhesive composition (a composition in which at least a portion of the adhesive is dispersed in water). A solvent-type adhesive composition refers to an adhesive composition in which an adhesive is contained in an organic solvent. The technology disclosed herein can preferably be implemented in a form comprising an adhesive layer formed from a solvent-type adhesive composition, from the viewpoint of adhesive properties, etc.

[0079] (Formation of the adhesive layer) The adhesive layer disclosed herein can be formed by conventionally known methods. For example, a direct method can be employed in which the adhesive layer is formed by directly applying (typically coating) the adhesive composition to a base film as described above and drying it. Alternatively, a transfer method can be employed in which the adhesive layer is formed on a surface that has peelability (release surface) by applying the adhesive composition and drying it, and then the adhesive layer is transferred to the base film. From the viewpoint of productivity, the transfer method is preferred. As the release surface, the surface of a release liner or the back surface of a released base film can be used. Although the adhesive layer disclosed herein is typically formed continuously, it is not limited to this form, and may be formed in a regular or random pattern such as dots or stripes.

[0080] The adhesive composition can be applied using conventionally known coaters, such as gravure roll coaters, die coaters, or bar coaters. Alternatively, the adhesive composition may be applied by impregnation or curtain coating methods. From the viewpoint of promoting the crosslinking reaction and improving manufacturing efficiency, it is preferable to dry the adhesive composition under heating. The drying temperature can be, for example, around 40 to 150°C, and is usually preferably around 60 to 130°C. After drying the adhesive composition, aging may be performed for purposes such as adjusting the migration of components within the adhesive layer, promoting the crosslinking reaction, and alleviating any strain that may exist within the base film or adhesive layer.

[0081] The thickness of the adhesive layer is not particularly limited. From the viewpoint of reducing the weight of the adhesive sheet, the thickness of the adhesive layer is usually appropriate to be approximately 200 μm or less, preferably approximately 100 μm or less, and more preferably approximately 75 μm or less (for example, approximately 60 μm or less). The thickness of the adhesive layer can be approximately 55 μm or less, for example, it may be approximately 50 μm or less, and even more preferably approximately 40 μm or less. There is no particular lower limit to the thickness of the adhesive layer, but from the viewpoint of making the most of the adhesive properties of the adhesive layer, it is advantageous to have a thickness of approximately 5 μm or more, it is appropriate to have a thickness of approximately 10 μm or more, preferably approximately 20 μm or more, more preferably approximately 30 μm or more, and it may also be approximately 35 μm or more.

[0082] The storage modulus of the adhesive layer is not particularly limited. In a preferred embodiment, the storage modulus of the adhesive layer at 0°C is 1.0 × 10⁻⁶. 4 Pa or higher, more preferably 5.0 × 10 4 Pa or higher, more preferably 1.0 × 10 5 Pa or higher, particularly preferably 1.2 × 10⁻⁶ 5 It is Pa or higher. The upper limit of the storage modulus of the adhesive layer at 0°C is not particularly limited, but is preferably 1.5 × 10⁻⁶. 6 It is less than or equal to Pa, and more preferably 1.0 × 10⁻⁶ 6 Pa or less, more preferably 8.0 × 10 5 Pa or less, particularly preferably 7.5 × 10 5 It is below Pa. When the storage modulus of the adhesive layer at 0°C is within the above range, the adhesiveness tends to improve.

[0083] In the technology disclosed herein, the 0°C storage modulus of the adhesive layer can be determined by dynamic viscoelasticity measurement. Specifically, an adhesive layer with a thickness of approximately 2 mm is prepared by stacking multiple adhesive layers to be measured. A sample of this adhesive layer, punched into a disc shape with a diameter of 7.9 mm, is fixed by sandwiching it between parallel plates, and dynamic viscoelasticity measurement is performed using a viscoelasticity tester (e.g., ARES or equivalent manufactured by T.A. Instruments) under the following conditions to determine the 0°C storage modulus. • Measurement mode: Shear mode Temperature range: -70℃ to 150℃ • Heating rate: 5°C / min ·Measurement frequency: 1Hz The adhesive layer to be measured can be formed by applying the corresponding adhesive composition in layers and then drying or curing it.

[0084] <Removable Liner> In the technologies disclosed herein, release liners can be used in the formation of adhesive layers, the manufacture of adhesive sheets, storage of adhesive sheets before use, distribution, and shaping. The release liners are not particularly limited, and for example, release liners having a release treatment layer on the surface of a liner substrate such as a resin film or paper, or release liners made of low-adhesion materials such as fluoropolymers (polytetrafluoroethylene, etc.) or polyolefin resins (polyethylene, polypropylene, etc.) can be used. The release treatment layer may be formed by surface treating the liner substrate with a release treatment agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide agent.

[0085] <Thickness of adhesive sheet> The total thickness of the adhesive sheet disclosed herein (including the adhesive layer and the support substrate, but not the release liner) is not particularly limited. The total thickness of the adhesive sheet can be, for example, approximately 350 μm or less, and from the viewpoint of weight reduction, it is usually appropriate to be approximately 200 μm or less, preferably 150 μm or less. The lower limit of the thickness of the adhesive sheet is not particularly limited, and it can usually be approximately 20 μm or more, for example, it is appropriate to be approximately 50 μm or more, preferably approximately 75 μm or more, more preferably approximately 90 μm or more (for example, approximately 100 μm or more).

[0086] The ratio of the thickness of the adhesive layer to the total thickness of the adhesive sheet is not particularly limited. In the technology disclosed herein, for example, it is appropriate for the ratio of the thickness of the adhesive layer to the total thickness of the adhesive sheet to be 75% or less, preferably 60% or less, more preferably 50% or less, and even more preferably 45% or less. By configuring it in this way, the properties of the supporting substrate can be made more effective. The lower limit of the ratio of the thickness of the adhesive layer to the total thickness of the adhesive sheet is not particularly limited, but it is usually appropriate to be 5% or more, preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more. By configuring it in this way, the adhesive properties of the adhesive layer can be made more effective.

[0087] <Supporting base material> The adhesive sheet disclosed herein includes a support substrate. The structure and materials of the support substrate disclosed herein are not particularly limited. The support substrate is typically a film-like substrate (also referred to as the "substrate film"). Preferably, the substrate film includes a resin film as the base film. The base film is typically an independently shape-retaining (independent) component. The substrate film in the disclosed technology may be substantially composed of such a base film. Alternatively, the substrate film may include auxiliary layers in addition to the base film. Examples of such auxiliary layers include a colored layer, a reflective layer, a primer layer, an antistatic layer, etc., provided on the surface of the base film.

[0088] The above-mentioned resin film is a film whose main component is a resin material (for example, a component that is present in the resin film in an amount exceeding 50% by weight). Examples of resin films include polyolefin resin films such as polyethylene (PE), polypropylene (PP), and ethylene-propylene copolymer; polyester resin films such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN); polyurethane resin films; vinyl chloride resin films; vinyl acetate resin films; polyimide resin films; polyamide resin films; fluororesin films; cellophane; and the like. The resin film may also be a rubber film such as natural rubber film or butyl rubber film. Among these, polyester films are preferred because they have good handling and processability, and possess the heat resistance required for adhesive sheets for bicycle rims, and among polyester films, PET films are particularly preferred. In this specification, "resin film" is typically a non-porous sheet and is a concept distinct from so-called nonwoven fabrics and woven fabrics (in other words, a concept excluding nonwoven fabrics and woven fabrics).

[0089] The substrate film may be colored by a colored layer disposed on the surface of the base film (preferably a resin film). A substrate film with a colored layer in this configuration tends to have excellent opacity and design properties for the adherend. In a substrate film with a base film and a colored layer, the base film may or may not contain a coloring agent. The colored layer may be disposed on either one surface of the base film, or on both surfaces. In a configuration where colored layers are disposed on both surfaces of the base film, the configurations of these colored layers may be the same or different.

[0090] Such a colored layer can typically be formed by applying a colored layer-forming composition containing a colorant and a binder to a base film. Conventionally known pigments and dyes can be used as the colorant. Colored colorants are preferred. The color of the colorant may be, for example, black, gray, red, blue, yellow, green, yellow-green, orange, purple, gold, silver, pearl, etc. Colored colorants tend to have excellent opacity and design properties for the substrate. Since bicycle rims are often black, it is preferable to use a black colorant that offers excellent design properties for them. The colorant may or may not contain a colorless colorant in combination with the colored colorant. A base film according to a typical embodiment disclosed herein may substantially not contain a colorless colorant. In this specification, "colored" includes black and metallic colors, and "colorless" includes white.

[0091] As the binder, any material known in the field of paints or printing can be used without particular limitations. Examples include polyurethane, phenolic resin, epoxy resin, urea-melamine resin, and polymethyl methacrylate. The composition for forming the colored layer may be solvent-based, UV-curing, or thermosetting. The colored layer can be formed by employing any conventional method used for forming colored layers without particular limitations. For example, a method of forming the colored layer (printed layer) by printing such as gravure printing, flexographic printing, or offset printing can be preferably employed.

[0092] The colored layer may be a single-layer structure consisting of one layer, or it may be a multilayer structure including two, three or more sub-colored layers. A multilayer colored layer including two or more sub-colored layers can be formed, for example, by repeatedly applying (e.g., printing) a colored layer-forming composition. The color and amount of colorant contained in each sub-colored layer may be the same or different. For colored layers intended to provide aesthetic appeal, a multilayer structure is particularly beneficial from the viewpoint of preventing the occurrence of pinholes and enhancing aesthetic appeal.

[0093] The overall thickness of the colored layer is usually appropriate to be about 1 μm to 10 μm, preferably about 1 μm to 7 μm, and can be, for example, about 1 μm to 5 μm. In a colored layer that includes two or more sub-colored layers, the thickness of each sub-colored layer is usually preferably about 1 μm to 2 μm.

[0094] In a base film having a colored layer disposed on the surface of a base film (preferably a resin film), the colored layer may be disposed on the side of the adhesive layer, on the opposite side of the adhesive layer, or on both sides. In a preferred embodiment of the technology disclosed herein, the colored layer is disposed on the surface of the base film on the side of the adhesive layer. With this configuration, the colored layer is sandwiched and protected between the base film and the adhesive layer, which helps to suppress the occurrence of the colorant detaching due to friction on the surface of the adhesive sheet, causing the adhesive sheet to lose its color.

[0095] The base film (typically a resin film) may contain a colorant. A base film containing a colorant in this way tends to have excellent opacity and design properties of the adherend. Conventionally known pigments and dyes can be used as the colorant to be contained in the base film. In one preferred embodiment of the art disclosed herein, the base film is a base film containing a black colorant, more specifically, a resin film into which a black colorant has been kneaded. Here, a base film into which a black colorant has been kneaded means a base film in which a black colorant has been mixed into the main constituent material of the base film (the material that is most abundant in the base film; typically a resin material). The black colorant is contained substantially in a dispersed state in the base film.

[0096] As the black coloring agent included in the base film, organic or inorganic coloring agents (pigments, dyes, etc.) can be used. Specific examples of black coloring agents include carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, pine soot, etc.), graphite, copper oxide, manganese dioxide, aniline black, perylene black, titanium black, cyanine black, activated carbon, ferrite (non-magnetic ferrite, magnetic ferrite, etc.), magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complexes, anthraquinone-based coloring agents, etc. Among these, carbon black is preferred.

[0097] The black coloring agent is not particularly limited, and particulate coloring agents (pigments) can be preferably used. In a preferred embodiment, a black coloring agent (for example, a black pigment such as carbon black) with an average particle size of about 10 nm or more (for example, about 50 nm or more) can be used. The upper limit of the average particle size of the above black coloring agent is not particularly limited, and is usually about 500 nm or less, preferably about 300 nm or less, more preferably about 250 nm or less, for example, 200 nm or less (for example, about 120 nm or less). In this specification, "average particle size" refers to the particle size at 50% of the cumulative value in the particle size distribution measured based on a particle size distribution measuring device based on the laser scattering-diffraction method (50% volume average particle diameter; hereinafter sometimes abbreviated as D50).

[0098] The amount of colorant used in the base film is not particularly limited and can be adjusted as appropriate to impart the desired design. The amount of black colorant used is usually appropriate to be about 0.1 to 30% by weight of the total weight of the base film, for example, 0.1 to 25% by weight (typically 0.1 to 20% by weight).

[0099] The substrate film disclosed herein may contain colorants other than black colorants (pigments and dyes). Examples of such non-black colorants include white colorants. Examples of white colorants include titanium dioxide (such as rutile titanium dioxide and anatase titanium dioxide), zinc oxide, aluminum oxide, silicon oxide, zirconium oxide, magnesium oxide, calcium oxide, tin oxide, barium oxide, cesium oxide, yttrium oxide, magnesium carbonate, calcium carbonate (such as light calcium carbonate and heavy calcium carbonate), barium carbonate, zinc carbonate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, aluminum silicate, magnesium silicate, and calcium silicate. Examples include inorganic white colorants such as um, barium sulfate, calcium sulfate, barium stearate, zinc oxide, zinc sulfide, talc, silica, alumina, clay, kaolin, titanium phosphate, mica, gypsum, white carbon, diatomaceous earth, bentonite, lithopone, zeolite, sericite, and hydrated halloysite, as well as organic white colorants such as acrylic resin particles, polystyrene resin particles, polyurethane resin particles, amide resin particles, polycarbonate resin particles, silicone resin particles, urea-formaldehyde resin particles, and melamine resin particles.

[0100] The amount of non-black colorant used in the base film is not particularly limited and can be adjusted as appropriate to provide the desired design. The amount of non-black colorant used is usually appropriate to be about 0.1 to 30% by weight of the resin film, for example, 0.1 to 25% by weight (typically 0.1 to 20% by weight).

[0101] The above-mentioned base film may contain various additives as needed, such as fillers (inorganic fillers, organic fillers, etc.), dispersants (surfactants, etc.), anti-aging agents, antioxidants, UV absorbers, antistatic agents, lubricants, and plasticizers. The proportion of each additive is usually less than 30% by weight (for example, less than 20% by weight, typically less than 10% by weight).

[0102] The above-mentioned base film may have a single-layer structure, or it may have a multilayer structure of two, three, or more layers. From the viewpoint of shape stability, a single-layer structure of the base film is preferable. In the case of a multilayer structure, it is preferable that at least one layer (preferably all layers) is a layer having a continuous structure of the above-mentioned resin (e.g., polyester resin). The method for manufacturing the base film (typically a resin film) is not particularly limited and may be any conventionally known method as appropriate. For example, conventionally known general film molding methods such as extrusion molding, inflation molding, T-die casting, and calender roll molding can be appropriately employed.

[0103] The thickness of the support substrate disclosed herein is not particularly limited. From the viewpoint of handling properties of the adhesive sheet, pressure resistance, and suitably mitigating steps in the adherend, the thickness of the support substrate is usually 35 μm or more, preferably 60 μm or more (e.g., 65 μm or more), more preferably 70 μm or more, and particularly preferably 75 μm or more. There is no particular upper limit to the thickness of the support substrate. The thickness of the support substrate is usually 250 μm or less, preferably 200 μm or less, more preferably 150 μm or less, even more preferably 125 μm or less, and particularly preferably 100 μm or less, from the viewpoint of weight reduction. When the support substrate is composed of a base film and a colored layer, the thickness of the support substrate may be the total thickness of the base film and the colored layer.

[0104] The surface of the base film may be subjected to conventionally known surface treatments such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, or application of a primer. Such surface treatments may be treatments to improve the adhesion between the base film and the adhesive layer, in other words, the anchoring ability of the adhesive layer to the base film. When the technology disclosed herein is implemented in the form of a single-sided adhesive sheet with a base, the back surface of the base film may be subjected to a release treatment as needed. The release treatment may be a treatment in which a release agent such as a general silicone-based, long-chain alkyl-based, or fluorine-based agent is applied in a thin film typically of about 0.01 μm to 1 μm (e.g., 0.01 μm to 0.1 μm). By applying such a release treatment, effects such as facilitating the unwinding of a roll of adhesive sheets can be obtained.

[0105] The matters disclosed in this specification include the following: (1) An adhesive sheet used to seal the spoke holes of a bicycle rim, It comprises a support substrate and an adhesive layer disposed on one surface of the support substrate, Under temperature conditions of 0°C, the peel strength measured 10 seconds after attachment to an aluminum plate (the adherend) at a tensile speed of 300 mm / min and a peel angle of 180 degrees is 2 N / 20 mm or higher. Under a temperature of 0°C, the shear adhesion force measured with an aluminum plate as the adherend was 200 N / 400 mm. 2 That's all for the adhesive sheet for bicycle rims. (2) The adhesive layer has a storage modulus of 1.0 × 10 at 0°C. 5 ~1.0×10 6 The adhesive sheet described in (1) above, which is Pa. (3) The adhesive sheet according to (1) or (2) above, wherein the adhesive layer is an acrylic adhesive layer containing an acrylic polymer. (4) The adhesive layer contains more than 50% by weight of polymer components. It contains acrylic polymers in proportion, The above acrylic polymer has the following monomer component: (1): CH2=C(R 1 )COOR 2 (1) (R in equation (1) above) 1 R is a hydrogen atom or a methyl group. 2 The adhesive sheet according to any one of (1) to (3) above, wherein is a chain alkyl group having 1 to 20 carbon atoms; ); contains 70% by weight or more of alkyl (meth)acrylate represented by ); (5) The adhesive sheet according to (4) above, wherein the acrylic polymer further comprises a carboxyl group-containing monomer as the monomer component. (6) The adhesive sheet according to any of (1) to (5) above, wherein the thickness of the adhesive layer is 30 μm or more and 75 μm or less. (7) The support substrate is an adhesive sheet according to any of (1) to (6) above, wherein the support substrate is a resin film substrate. (8) The support substrate is an adhesive sheet according to any one of (1) to (7) above, comprising a polyester film as the base film. (9) The adhesive sheet according to (8), wherein the support substrate further comprises a colored layer disposed on the surface of the base film on the adhesive layer side. (10) The adhesive sheet according to any of (1) to (9) above, wherein the thickness of the support substrate is 60 μm or more and 100 μm or less. (11) An adhesive sheet as described in any of (1) to (10) above, used to seal the spoke holes of a bicycle rim for tubeless tires. (12) An adhesive sheet roll, which is constructed by winding an adhesive sheet as described in any of (1) to (11) above, with the adhesive layer facing outwards. (13) A bicycle rim with an adhesive sheet attached, which is constructed by attaching any of the adhesive sheets described in (1) to (11) above. [Examples]

[0106] The following describes several embodiments of the present invention, but the present invention is not intended to be limited to those shown in these embodiments. In the following description, "parts" refers to weight unless otherwise specified.

[0107] <Example 1> (Preparation of acrylic polymers) 70 parts of n-butyl acrylate (BA), 30 parts of 2-ethylhexyl acrylate (2EHA), 3 parts of acrylic acid (AA), 0.05 parts of 4-hydroxybutyl acrylate (4HBA), and 0.08 parts of AIBN as a polymerization initiator were added to toluene as a solvent. The mixture was then solution polymerized at 63°C for 8 hours to prepare an acrylic polymer solution. The Tg of the acrylic polymer in the resulting acrylic polymer solution was -57°C.

[0108] (Preparation of adhesive composition) To the obtained acrylic polymer solution, 30 parts of the polymerized rosin pentaerythritol ester (Arakawa Chemical, Pencel D-125) and 3 parts of the isocyanate crosslinking agent (Nippon Polyurethane Co., Ltd., Coronate L) were added to prepare an acrylic adhesive composition. The storage modulus of the solids contained in the obtained adhesive composition at 0°C was 5 × 10⁻⁶. 5 It was Pa.

[0109] (Making adhesive sheets) As a release liner, a polyester release film (product name "Diafoil MRF", thickness 38 μm, manufactured by Mitsubishi Polyester Co., Ltd.) with a release surface on one side was prepared. The above adhesive composition was applied to the release surface of this release liner so that the thickness after drying was 35 μm, and it was dried at 100°C for 1 minute. In this way, an adhesive layer was formed on the release surface of the release liner. As the support substrate, a multilayer support substrate with a total thickness of approximately 80 μm was used, consisting of a 75 μm thick transparent PET film (product name "Lumirror", manufactured by Toray Industries, Inc.) and a black printed layer provided on one side of the PET film. The black printed layer was formed by using an ink composition containing a black coloring agent and performing five-layer printing using gravure printing. The adhesive sheet according to this example was prepared by laminating the adhesive layer formed on the release liner onto the surface of the support substrate on the side where the black printed layer was provided (transfer method). The release liner was left on the adhesive layer and used to protect the surface (adhesive surface) of the adhesive layer.

[0110] (Preparation of adhesive sheet rolls) By cutting the above-mentioned adhesive sheet with release liner, a sample for making a roll with a width of 25 mm and a length of approximately 50 m was prepared. Adhesive tape was also prepared to fix the ends of the winding core and the adhesive sheet. The diameter of the winding core and the type and size of the adhesive tape used to secure the ends are not particularly limited. For example, in this embodiment, a cylindrical core with an outer diameter of 82.5 mm, an inner diameter of 76.5 mm, and an axial length of 25 mm was prepared as the winding core. With the support substrate side of the sample for making the roll facing the inner circumference, one end of the sample in the longitudinal direction (the starting end) was fixed to the outer surface of the core with commercially available adhesive tape, and the remaining part of the sample was wound around the core to make an adhesive sheet roll. The other end of the sample in the longitudinal direction (the ending end) was fixed to the outer surface of the sample located on its inner circumference (the surface opposite to the adhesive layer of the release liner) with commercially available adhesive tape.

[0111] <Example 2> (Preparation of acrylic polymer emulsions) Forty parts of deionized water were placed in a reaction vessel equipped with a condenser, nitrogen inlet tube, thermometer, and stirrer, and stirred at 60°C for more than one hour while introducing nitrogen gas. Next, 0.1 parts of 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride were added to the reaction vessel as a polymerization initiator, and the mixture was stirred for one hour while introducing nitrogen gas, raising the temperature to 60°C. A monomer emulsion was then gradually added dropwise over four hours to allow the emulsion polymerization reaction to proceed. As the monomer emulsion, 85 parts of 2EHA, 13 parts of methyl acrylate (MA), 1.2 parts of AA, 0.75 parts of methacrylic acid (MAA), 0.048 parts of t-lauryl mercaptan (t-LSH) as a chain transfer agent, 0.02 parts of 3-methacryloxypropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd. trade name "KBM-503"), and 2 parts of polyoxyethylene lauryl sulfate sodium as an emulsifier were added to 30 parts of deionized water and emulsified. After the dropwise addition of the monomer emulsion was complete, the mixture was held at 60°C for 3 hours, and then 0.2 parts of 35% hydrogen peroxide solution and 0.6 parts of ascorbic acid were added. After cooling to room temperature, the pH was adjusted to 7 by adding 10% ammonium solution. In this way, an acrylic polymer emulsion was obtained. The Tg of the acrylic polymer contained in the obtained acrylic polymer emulsion was -60°C.

[0112] (Preparation of adhesive composition) To 100 parts of the acrylic polymer contained in the obtained emulsion, 5 parts of an aqueous emulsion of polymerized rosin ester with a softening point of 160°C (product name "E-865NT" from Arakawa Chemical Industries, Ltd.) were added as a tackifying resin, based on solid content, and mixed. Furthermore, the pH was adjusted to 8.0 and the viscosity to 10 Pa·s using 10% aqueous ammonium phosphate as a pH adjuster and polyacrylic acid (product name "Aron B-500" from Toagosei Co., Ltd.) as a thickener, to obtain the acrylic adhesive composition of this example. The storage modulus of the solids contained in the obtained adhesive composition at 0°C is 2 × 10⁻⁶ 5 It was Pa.

[0113] (Preparation of adhesive sheets and adhesive sheet rolls) An adhesive sheet was prepared in the same manner as in Example 1, except that the above adhesive composition was applied so that the thickness after drying was 50 μm. An adhesive sheet roll was prepared in the same manner as in Example 1, except that the above adhesive sheet was used.

[0114] <Example 3> (Preparation of acrylic polymer emulsions) In a reaction vessel equipped with a condenser, nitrogen inlet tube, thermometer, and stirrer, 0.1 parts of 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate (manufactured by Wako Pure Chemical Industries, Ltd., trade name "VA-057") as a polymerization initiator and 35 parts of deionized water were added. The mixture was stirred for 1 hour while introducing nitrogen gas and the temperature was raised to 60°C. A monomer emulsion was then gradually added dropwise over 4 hours to allow the emulsion polymerization reaction to proceed. The monomer emulsion used was prepared by adding 68 parts BA, 29.1 parts 2EHA, 2.9 parts AA, 0.05 parts dodecanethiol as a chain transfer agent, and 2 parts sodium polyoxyethylene alkyl ether sulfate as an emulsifier to 40 parts deionized water and emulsifying it. After the dropwise addition of the monomer emulsion was complete, the mixture was maintained at 60°C for another 2 hours, and then 0.1 parts of 35% hydrogen peroxide solution and 0.1 parts of ascorbic acid were added. After cooling to room temperature, the pH was adjusted to 7 by adding 10% ammonium aqueous solution. In this way, an emulsion of acrylic polymer was obtained. The Tg of the acrylic polymer contained in the obtained emulsion was -57°C.

[0115] (Preparation of adhesive composition) An adhesive composition was prepared by adding a tackifying resin emulsion at a ratio of 30 parts (based on solid content) to 100 parts of the acrylic polymer contained in the obtained emulsion. The tackifying resin emulsion used was "Tamanol E-200-NT," manufactured by Arakawa Chemical Industries, Ltd. Furthermore, the pH was adjusted to 8.0 and the viscosity to 10 Pa·s using 10% ammonium aqueous solution as a pH adjuster and polyacrylic acid ("Aron B-500," manufactured by Toagosei Co., Ltd.) as a thickener, resulting in the acrylic adhesive composition of this example. The storage modulus of the solid content of the obtained adhesive composition at 0°C was 7 × 10⁻⁶. 5 It was Pa.

[0116] (Preparation of adhesive sheets and adhesive sheet rolls) An adhesive sheet was prepared in the same manner as in Example 1, except that the above adhesive composition was applied so that the thickness after drying was 60 μm. An adhesive sheet roll was prepared in the same manner as in Example 1, except that the above adhesive sheet was used.

[0117] <Comparative Example 1> (Preparation of acrylic polymer solutions) 100 parts BA, 5 parts AA, and 150 parts toluene were charged into a polymerization vessel, and the mixture was purged with nitrogen at room temperature for 1 hour. The temperature was then raised to 60°C, 0.2 parts benzoyl peroxide was added as a polymerization initiator, and polymerization was carried out at 63°C for 7 hours to obtain an acrylic polymer solution. The Tg of the acrylic polymer in the obtained acrylic polymer solution was -50°C.

[0118] (Preparation of adhesive composition) To the obtained acrylic polymer solution, 20 parts of terpene-modified phenol resin (Sumitomo Bakelite Co., Ltd., PR-12603N), 20 parts of metaxyleneformaldehyde polycondensate (Mitsubishi Gas Chemical Co., Ltd., Nikanol H-80), 1 part of butylated melamine resin (DIC Corporation, Amidia J-820-60-N), and 2 parts of isocyanate-based crosslinking agent (Nippon Polyurethane Co., Ltd., Coronate L) were added to prepare an acrylic adhesive composition.

[0119] (Preparation of adhesive sheets and adhesive sheet rolls) An adhesive sheet was prepared in the same manner as in Example 1, except that the above adhesive composition was applied to a thickness of 30 μm after drying, and a 130 μm thick PE film (product name "No. 440," manufactured by Nitto Denko Corporation) with black pigment kneaded into it was used as the support substrate. An adhesive sheet roll was prepared in the same manner as in Example 1, except that the above adhesive sheet was used.

[0120] <Comparative Example 2> (Preparation of acrylic polymer solutions) 65 parts BA, 35 parts 2EHA, 6 parts AA, 0.05 parts 4HBA, and 0.08 parts AIBN as a polymerization initiator were added to toluene solvent. Solution polymerization was then carried out at 63°C for 8 hours to obtain an acrylic polymer solution. The Tg of the acrylic polymer in the obtained acrylic polymer solution was -55°C.

[0121] (Preparation of adhesive composition) An acrylic adhesive composition was prepared in the same manner as in Example 1, except that the above-mentioned acrylic polymer solution was used.

[0122] (Preparation of adhesive sheets and adhesive sheet rolls) Adhesive sheets and adhesive sheet rolls were prepared in the same manner as in Example 1, except that the above-mentioned adhesive composition was used.

[0123] <Comparative Example 3> (Preparation of acrylic polymer solutions) 35 parts BA, 65 parts 2EHA, 5 parts AA, 0.05 parts 4HBA, and 0.06 parts AIBN as a polymerization initiator were added to hexane solvent. Solution polymerization was then carried out at 70°C for 8 hours to obtain an acrylic polymer solution. The Tg of the acrylic polymer in the obtained acrylic polymer solution was -60°C.

[0124] (Preparation of acrylic adhesive composition) An acrylic adhesive composition was prepared in the same manner as in Example 1, except that the above-mentioned acrylic polymer solution was used.

[0125] (Preparation of adhesive sheets and adhesive sheet rolls) Adhesive sheets and adhesive sheet rolls were prepared in the same manner as in Example 1, except that the above-mentioned adhesive composition was used.

[0126] The monomer composition, polymerization method, and weight-average molecular weight (Mw) of each example acrylic polymer are shown in the corresponding column of Table 1.

[0127] (Peel strength S0 immediately after application at low temperature) Each example of the adhesive sheet was cut to a width of 20 mm and a length of 100 mm to serve as a sample for peel strength measurement. The above sample, along with an aluminum plate (manufactured by UACJ, product name Aluminum W13C1, surface roughness Ra=0.01~0.02 μm, alloy number A1085) as the adherend, and a 2 kg roller for application, were placed at 0°C for 60 minutes. Then, at 0°C, the adhesive side of the sample was applied to the adherend by moving the roller back and forth once at a speed of 5 mm / second. Ten seconds after application, the sample was peeled off the adherend at a tensile speed of 300 mm / min, in a 0°C environment, and at a peel angle of 180 degrees. The peel strength at this time was measured and defined as the low-temperature peel strength immediately after application. A tensile and compression testing machine (model number "TG-1kN") manufactured by Minebea Corporation was used for the measurement. The obtained results are shown in the corresponding column of Table 1.

[0128] (Low-temperature shear adhesion P0) Each example of the adhesive sheet was cut to a width of 20 mm and a length of 50 mm to be used as a sample for measuring shear adhesion strength. Under conditions of 23°C and 50% RH, an aluminum plate (manufactured by UACJ, product name Aluminum W13C1, surface roughness Ra=0.01~0.02 μm, alloy number A1085) was used as the substrate. The sample was positioned so that the longitudinal end overlapped 20 mm from the end of the substrate, and the other end of the sample opposite to the above end protruded from the above end of the substrate. A 2 kg roller was used to apply the sample to a 20 mm x 20 mm area by making one pass back and forth at a speed of 5 mm / second, and this was left for 30 minutes under conditions of 23°C and 50% RH. At this time, the portion of the sample protruding from the substrate (non-adhered portion) was backed with a 25 μm thick PET film (product name "Lumirror", manufactured by Toray Industries, Inc.). Next, after being left in a 0°C environment for 60 minutes, the unadhesive portion with the backing was clamped in a chuck and pulled in the shear direction (tensile angle 0 degrees) at a tensile speed of 300 mm / min in a 0°C environment, and the tensile strength at this time was measured to determine the low-temperature shear adhesion strength. A tensile and compression testing machine manufactured by Minebea Corporation (model number "TG-1kN") was used for the measurement. The obtained results are shown in the corresponding column of Table 1.

[0129] (Evaluation of workability) The process of wrapping each example's adhesive sheet roll around the outer circumference of the spoke connection area of ​​the bicycle rim (hereinafter also referred to as the rim interior) was carried out as follows. Under a temperature of 0°C, first, the adhesive sheet roll was slightly unwound, and the tip of the adhesive sheet was attached to a certain point (starting point) on the outer circumference of the rim interior. Next, the adhesive sheet was further unwound and wrapped around the entire outer circumference (one full turn) of the rim interior. The release liner provided on the surface of the adhesive layer was peeled off from the tip of the adhesive sheet to the point where it was unwound as the adhesive sheet was unwound. If the tip of the adhesive sheet did not peel off from the starting point during the process and the work was completed, it was marked with ○. If the tip of the adhesive sheet peeled off during the process, it was marked with ×. The results obtained are shown in the corresponding column of Table 1.

[0130] [Table 1]

[0131] As is clear from the results shown in Table 1, the peel strength immediately after low-temperature application is 2N / 20mm or higher, and the low-temperature shear adhesion strength is 200N / 400mm. 2 The adhesive sheets of Examples 1 to 3 described above were found to have better workability in wrapping around the spoke connection area of ​​a bicycle rim compared to Comparative Examples 1 to 3, in which at least one of the low-temperature peel strength immediately after application and the low-temperature shear adhesive strength was outside the above range.

[0132] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. [Explanation of Symbols]

[0133] 10 Wheels with tubeless tires 12 wheels 14 Hubs 16 rim 18 spokes 20 tires 32 spoke holes 40 Adhesive Sheets 50 wheels with inner tube tires 60 Supporting base material 64 Adhesive layer 66 Adhesive surface 68 Release Liner 70 Adhesive sheets with release liner

Claims

1. An adhesive sheet used to seal the spoke holes of a bicycle rim, It comprises a support substrate and an adhesive layer disposed on one surface of the support substrate, The support substrate includes a base film and a colored layer disposed on the surface of the base film on the adhesive layer side. Under temperature conditions of 0°C, the peel strength measured 10 seconds after attachment to an aluminum plate as the adherend, at a tensile speed of 300 mm / min and a peel angle of 180 degrees, is 2 N / 20 mm or more. Under a temperature condition of 0°C, the shear adhesion force measured with an aluminum plate as the adherend was 200 N / 400 mm. ２ That's all for the adhesive sheet for bicycle rims.

2. The adhesive layer has a storage modulus of 1.0 × 10⁻⁶ at 0°C. ５ ~1.0 x 10 ６ The adhesive sheet according to claim 1, wherein the material is Pa.

3. The adhesive sheet according to claim 1 or 2, wherein the adhesive layer is an acrylic adhesive layer containing an acrylic polymer.

4. The adhesive sheet according to claim 1 or 2, wherein the thickness of the adhesive layer is 30 μm or more and 75 μm or less.

5. The adhesive sheet according to claim 1 or 2, wherein the support substrate is a resin film substrate.

6. The adhesive sheet according to claim 1 or 2, wherein the support substrate includes a polyester film as the base film.

7. The adhesive sheet according to claim 1 or 2, wherein the thickness of the support substrate is 60 μm or more and 100 μm or less.

8. An adhesive sheet according to claim 1 or 2, used to seal spoke holes in a bicycle rim for tubeless tires.

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